Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
PDM TRANSMISSION WITH SLIDING CONTACT BETWEEN
CONVEX SHAFT PINS AND CONCAVE BEARINGS SURFACES
[0001]
FIELD OF THE DISCLOSURE
[0002] This disclosure is directed generally to rotary power transmission
assemblies
particularly adapted for use in bottom hole assemblies ("BHAs") in order to
transfer torque
generated by a subterranean positive displacement motor ("PDM") to, for
example, a rotary drill
bit. In some embodiments, this disclosure is directed more specifically to
such a transmission
assembly using laminated rubber (or other elastomer) bearings elements having
a "bridge"-style
geometry in which a planar face opposes a generally concave curved face. In
other
embodiments, this disclosure is directed to transmission assembly embodiments
using
unlaminated or "monolithic" bearings elements (made of materials such as
metal) that preferably
also have the 'bridge"-style geometry.
BACKGROUND OF THE DISCLOSED TECHNOLOGY
[0003] It is well understood that bottom hole assemblies ("BHAs") include
rotating power
shafts that are necessarily misaligned by virtue of the BHA's design. For
example, the rotation
of the rotor in the PDM is eccentric and not concentric. This eccentric
rotation of the rotor must
be resolved into concentric rotation that will ultimately rotate the bit.
Further, directional drilling
- 1 -
Date Recue/Date Received 2022-02-25
in deviated wellbores necessarily causes misalignment of rotating power shafts
in interconnected
BHA components.
[0004] Specialized transmission sections designed for downhole applications
transfer torque
between such misaligned shafts. Conventionally, PDM transmission designs
resolve the
misalignment between input/output shafts via contact between cooperating
components on each
of the input and output shafts, and torque is transferred from input shaft to
output shaft through
internal bearings contact. Conventionally, such internal bearings contact is
typically metal-to-
metal. The metal-to-metal contact surfaces can deteriorate rapidly on some
conventional
designs, and in some downhole work environments. Deterioration can be a
particular problem
under heavy torque load. Such deterioration may shorten the service life of
the transmission.
Notable effects causing such shortened service life include galling of the
metal-to-metal contact
surfaces and resulting fretting and general erosion of the metal.
[0005] There are several types of PDM transmission designs known in the art.
Constant
Velocity (or CV) joint styles include: (1) ball bearing designs, in which
torque is transferred via
a pre-designed number of mating ball and socket couplings (typically 6 to 8);
(2) spline designs,
in which the cooperating metal surfaces have interlocking splines and
receptacles; (3) woodruff
key designs, in which torque is transferred via wedges, semicircles or other
shapes; and (4)
elliptical roller bearing designs, which are similar to ball bearing designs
except with elongated
ball and socket couplings (i.e. elliptical shapes) in order to provide more
contact length in each
coupling for better torque load distribution and transfer.
[0006] Other PDM transmission styles known in the art include: (1) flex shaft
designs, in
which an elongated input shaft resolves eccentric rotation into concentric
rotation by flexing over
its length; (2) flex shaft/CV joint combination and hybrid designs; and (3)
knuckle joint designs,
- 2 -
Date Recue/Date Received 2022-02-25
in which opposing tabs and slots interlock in a bending "knuckle"
configuration to transfer
torque with high sliding force contact and drilling mud exposure.
[0007] Even small amounts of fretting and other erosion can also cause loss of
design
kinematics in conventional transmission designs with metal/metal contact. Such
loss in design
kinematics can compromise the original design intent to transfer torque by
distributed contact
between multiple elements in the bearing surfaces provided in the conventional
designs
described above. The loss in distributed bearing contact manifests itself as a
corresponding loss
in torque transfer efficiency, caused by such effects as a change of
transmission angle and erratic
torque transfer through the bearing surfaces. In such cases, conventional
transmissions may
perform differently from specification over time (and usually not as well).
More specifically, the
surfaces of the bearings contacts in such designs become recessed away from
the optimum 90-
degree transmission angle and do not engage sliding surfaces at the same
offset location or angle
at which they were designed to operate. This causes irregular engagement
between bearings
surfaces and leads to stress concentrations not anticipated by original design
considerations.
Eventually, over time, the non-uniform wear of the bearings surfaces can cause
transmission
designs with two, three, four or more contacts to be driven by only one or two
bearing surfaces,
especially during instantaneous dynamic movement. This leads to accelerated
wear and lateral
misalignment. The lateral misalignment will also cause an increased orbiting
lateral or
transverse force during transmission rotation for which the bearing
arrangement may not be
designed.
[0008] As noted, all of the foregoing existing styles of transmission have
service life issues
caused, at least in part, by deterioration of the bearings contact
interface(s). Abaco's U.S. patent
application Serial No. 15/721,959 (now U.S. Patent 10,934,778) (hereafter
"Parent Application")
- 3 -
Date Recue/Date Received 2022-02-25
discloses laminated "bridge"-style bearings designs and embodiments addressing
some of the
above-described problems and needs in the prior art with laminated torsional
bearings that flex
rather than slide in providing torque transfer during misaligned (articulated)
rotation. The
present disclosure enlarges upon the Parent Application with description of
unlaminated
"bridge"-style bearings embodiments. In such embodiments, curve bearing
surfaces (and
preferably convex curved bearing surfaces) on transmission shaft pins are
allowed to slidably
rotate against corresponding curved surfaces (and preferably concave curved
bearing surfaces)
on the unlaminated bearing elements as the shaft "tilts" during misaligned
rotation with respect
to a housing. The unlaminated "bridge"-style bearings of the present
disclosure are further free
to slidably displace within receptacles provided in the periphery of the
housing.
SUMMARY AND TECHNICAL ADVANTAGES
[0009] These and other drawbacks in the prior art are addressed in the Parent
Application by a
transmission providing laminated bearing embodiments including a contact
interface between an
input shaft and output shaft, in which the input and output shafts are
misaligned. It will be
appreciated that in a BHA application, the input shaft may typically be
connected to the rotor of
a PDM, and the output shaft to a flex shaft / constant velocity (CV) joint as
part of the linkage
ultimately connecting to a rotating bit. The transmission in the Parent
Application provides an
interlocking mechanism in which an input shaft adapter, on the end of the
input shaft, is received
into a recess in an output shaft adapter on the end of the output shaft. More
specifically, shaped
pins provided on the outer periphery of the input shaft adapter are received
into shaped
receptacles provided in the recess in the output shaft adapter. Shaped
laminated torsional
bearings are also placed within the confines of the receptacle, interposed
between the input shaft
adapter pins and the side walls of the receptacle.
- 4 -
Date Recue/Date Received 2022-02-25
[0010] Embodiments of the laminated torsional bearings disclosed in the Parent
Application
provide (1) a curved rubber/metal laminate portion to mate with a
corresponding curved bearing
surface of the input shaft adapter pins, and (2) a flat rubber/metal laminate
portion to bear on the
side walls of the receptacle. Specifically, the input shaft adapter pins bear
upon the curved
laminate portions of the torsional bearings, and the flat laminate portions of
the torsional
bearings bear on the side walls of the output shaft adapter receptacles. Thus,
when torque is
applied to the input shaft, torque is transmitted to the output shaft via flex
in the torsional
bearings rather than via sliding of contact surfaces.
[0011] The curved and flat laminate portions of the torsional bearings
embodiments disclosed
in the Parent Application are preferably made of alternating metal layer and
rubber layer
construction. The deployment of the torsional bearings between input shaft
adapter pins and
output shaft adapter receptacles is designed to avoid, or at least to
minimize, relative sliding
contact between bearing surfaces during transmission of torque. That is, the
laminate design
described in the Parent Application is such that transmission of torque, at
least primarily, is via
flex: (1) between the contact surfaces of the input shaft adapter pins and the
curved laminate
portions on the torsional bearings, and (2) between the contact surfaces of
the flat laminate
portions on the torsional bearings and the side walls of the output shaft
adapter receptacles.
Advantageously, adhesive may be used on the contact surfaces during assembly
and service to
inhibit sliding movement. In this way, according to laminated bearings
embodiments described
in the Parent Application, misalignment of input and output shafts during
articulated shaft
rotation is taken up by flex of the elastomeric layers in the curved and flat
laminate portions of
the torsional bearings, obviating sliding bearings contact and its associated
drawbacks as
described above in the Background section.
- 5 -
Date Recue/Date Received 2022-02-25
[0012] As noted above, the present disclosure enlarges upon the Parent
Application with
description of unlaminated "bridge"-style bearings embodiments. Dissimilar
from the laminated
bridge-style bearings embodiments described in the Parent Application (which
are designed to
flex rather than slide against shaft pins when taking up misaligned rotation),
the unlaminated
"bridge"-style bearings of the present application are designed so that the
unlaminated bridge-
shaped bearing elements (also referred to herein as "torque transfer elements"
or "TTEs")
promote sliding contact between curved surfaces on pins on the shaft and
curved surfaces on the
TTEs. Preferably, convex bearing surfaces provided on the transmission shaft
pins are
configured to slidably rotate against corresponding concave bearing surfaces
on the unlaminated
TTEs. In preferred embodiments, rotation of the shaft pins about the TTEs is
about a generally
radial axis centered on the shaft pins and orthogonal to the shaft's
longitudinal axis.
[0013] With reference now to the "Background" section above, unlaminated
bearings
embodiments set forth in this disclosure address contact surface erosion and
degradation
problems described in the "Background" section in different ways than
addressed by the
laminated bearings embodiments described in the Parent Application.
Unlaminated bearings
embodiments as set forth in this disclosure are not configured to flex in
order to limit sliding
contact between transmission components. Unlaminated bearings designs as set
forth in this
disclosure necessarily require sliding contact between transmission components
(such sliding
contact preferably primarily comprising sliding rotation contact between
convex bearing surfaces
provided on the shaft pins and corresponding concave bearing surfaces on the
unlaminated
TTEs). However, unlaminated bearings embodiments as set forth in this
disclosure are
configured to optimize sliding contact between transmission components so that
the prior art's
- 6 -
Date Recue/Date Received 2022-02-25
contact surface deterioration problems are addressed and contact surface
deterioration typically
seen in conventional designs is reduced.
[0014] In a first aspect, therefore, this disclosure describes embodiments of
a torque
transmission comprising: an input shaft adapter having first and second ends,
the first end of the
input shaft adapter configured to mate with an input shaft, the second end of
the input shaft
adapter providing a plurality of pins disposed on an outer surface of the
input shaft adapter, each
pin providing a curved pin portion; an output shaft adapter having first and
second ends, the
second end of the output shaft adapter configured to mate with an output
shaft, the first end of
the output shaft adapter providing a recess formed therein; a plurality of
notches formed in a
recess periphery of the recess, one notch for each pin disposed on the input
shaft adapter,
wherein the recess is shaped and sized to receive the second end of the input
shaft adapter such
that when the second end of the input shaft adapter is received inside the
recess, each pin on the
input shaft adapter is received into a corresponding notch on the recess; a
plurality of torsional
bearings, a curved laminate portion provided on each torsional bearing; and
wherein one
torsional bearing is interposed between one pin and one corresponding notch
when the pins are
received into their corresponding notches, such that the curved laminate
portion contacts the
curved pin portion; and wherein selected torsional bearings each further
comprise a flat portion,
each flat portion contacting the notch when the pins are received into their
corresponding
notches.
[0015] In some embodiments according to the first aspect, selected flat
portions of the
torsional bearings are laminated.
- 7 -
Date Recue/Date Received 2022-02-25
[0016] In some embodiments according to the first aspect, each pin has a
maximum pin nose
diameter, and in which selected pin nose diameters are on a locus that
coincides with an outer
diameter of the output shaft.
[0017] In some embodiments according to the first aspect, the torque
transmission further
comprises a spherical bearing, the spherical bearing including a spherical
bearing laminate
portion; and a tip, the tip provided on second end of the input shaft adapter;
wherein, when the
second end of the input shaft adapter is received inside the recess, the
spherical bearing laminate
portion is interposed between the tip and the recess.
[0018] In some embodiments according to the first aspect, selected curved
laminate portions
include metal and elastomer layers.
[0019] In some embodiments according to the first aspect, selected flat
portions of the
torsional bearings include a laminate comprising metal and elastomer layers.
[0020] In some embodiments according to the first aspect, the spherical
bearing laminate
portion includes metal and elastomer layers.
[0021] In some embodiments according to the first aspect, the torque
transmission further
comprises a boot retainer, the boot retainer having first and second boot
retainer ends; and an
outer input shaft adapter periphery on the second end of the input shaft
adapter and an outer
output shaft adapter periphery on the first end of the output shaft adapter;
wherein, when the
second end of the input shaft adapter is received inside the recess, the boot
retainer is received
over the input shaft adapter and the output shaft adapter such that the first
end of the boot
retainer is affixed to the outer input shaft adapter periphery and the second
end of the boot
retainer is affixed to the outer output shaft adapter periphery.
- 8 -
Date Recue/Date Received 2022-02-25
[0022] In some embodiments according to the first aspect, the torque
transmission further
comprises an outer output shaft adapter periphery on the first end of the
output shaft adapter; a
fill port connecting the outer output shaft adapter periphery to the recess;
and an evacuate port
connecting the outer output shaft adapter periphery to the recess.
[0023] In some embodiments according to the first aspect, the torque
transmission further
comprises adhesive bonding between curved pin portions and curved laminate
portions.
[0024] In some embodiments according to the first aspect, the torque
transmission further
comprises adhesive bonding between flat portions and notches.
[0025] In some embodiments according to the first aspect, the torque
transmission further
comprises adhesive bonding between the spherical bearing laminate portion and
at least one of
the tip and the recess.
[0026] In some embodiments according to the first aspect, selected pins each
have a midpoint,
and in which the curved pin portions on said selected pins each have a radius
whose centerpoint
coincides with the midpoint.
[0027] In a second aspect, this disclosure describes embodiments of a double
knuckle
transmission coupling, comprising: an input shaft having a first input shaft
end and a second
input shaft end, the second input shaft end having an input shaft slot
defining an input shaft
tongue and groove configuration; an output shaft having a first output shaft
end and a second
output shaft end, the first output shaft end having an output shaft slot
defining an output shaft
tongue and groove configuration; a plurality of arcuate tongue recesses, one
arcuate recess
formed in each tongue in the input and output shaft tongue and groove
configurations; a center
coupling element, the center coupling element including two pairs of knuckles,
each knuckle
providing an arcuate knuckle surface configured to be received within a
corresponding arcuate
- 9 -
Date Recue/Date Received 2022-02-25
tongue recess; a plurality of receptacles, one receptacle formed in each
arcuate tongue recess; a
plurality of torsional bearings, a curved laminate portion provided on each
torsional bearing;
wherein one torsional bearing is received into each receptacle, such that the
curved laminate
portions contact the arcuate knuckle surfaces when the knuckles are received
within their
corresponding arcuate tongue recesses.
[0028] The second aspect may include embodiments in which selected torsional
bearings each
further comprise a flat laminate portion, each flat laminate portion
contacting the receptacle
when the selected torsional bearings are received into their corresponding
receptacles.
[0029] In a third aspect, this disclosure describes embodiments of a torque
transmission,
comprising: an input shaft adapter having first and second ends, the first end
of the input shaft
adapter configured to mate with an input shaft, the second end of the input
shaft adapter
providing a plurality of pins disposed on an outer surface of the input shaft
adapter, each pin
providing a curved pin portion; an output shaft adapter having first and
second ends, the second
end of the output shaft adapter configured to mate with an output shaft, the
first end of the output
shaft adapter providing a recess formed therein; a plurality of notches formed
in a recess
periphery of the recess, one notch for each pin disposed on the input shaft
adapter, wherein the
recess is shaped and sized to receive the second end of the input shaft
adapter such that when the
second end of the input shaft adapter is received inside the recess, each pin
on the input shaft
adapter is received into a corresponding notch on the recess; a plurality of
bearings, a curved
portion provided on each bearing; and wherein one bearing is interposed
between one pin and
one corresponding notch when the pins are received into their corresponding
notches, such that
the curved portion of the bearing contacts the curved pin portion; and wherein
selected bearings
- 10 -
Date Recue/Date Received 2022-02-25
each further comprise a flat portion, each flat portion contacting the notch
when the pins are
received into their corresponding notches.
[0030] The third aspect may include embodiments in which selected ones of the
curved
portions of the bearings and the flat portions of the bearings include a
laminate. In such
embodiments, the laminate may comprise metal and elastomer layers.
[0031] The third aspect may also include embodiments further comprising: a
boot retainer, the
boot retainer having first and second boot retainer ends; and an outer input
shaft adapter
periphery on the second end of the input shaft adapter and an outer output
shaft adapter periphery
on the first end of the output shaft adapter; wherein, when the second end of
the input shaft
adapter is received inside the recess, the boot retainer is received over the
input shaft adapter and
the output shaft adapter such that the first end of the boot retainer is
affixed to the outer input
shaft adapter periphery and the second end of the boot retainer is affixed to
the outer output shaft
adapter periphery.
[0032] The third aspect may also include embodiments further comprising: an
outer output
shaft adapter periphery on the first end of the output shaft adapter; a fill
port connecting the outer
output shaft adapter periphery to the recess; and an evacuate port connecting
the outer output
shaft adapter periphery to the recess.
[0033] The third aspect may also include embodiments in which selected pins
each have a
midpoint, and in which the curved pin portions on said selected pins each have
a radius whose
centerpoint coincides with the midpoint.
[0034] The third aspect may also include embodiments in which each pin has a
maximum pin
nose diameter, and in which selected pin nose diameters are on a locus that
coincides with an
outer diameter of the output shaft.
- 1 1 -
Date Recue/Date Received 2022-02-25
[0035] In a fourth aspect, this disclosure describes embodiments of an
articulated transmission
disposed to transmit torque via misaligned rotation, the transmission
comprising: a shaft having
an axial shaft centerline about which the shaft is disposed to rotate; a
plurality of shaft pins, each
shaft pin extending radially from the shaft centerline, each shaft pin further
providing a curved
shaft pin bearing surface thereon; a generally cylindrical housing having an
axial housing
centerline about which the housing is disposed to rotate, the housing having a
plurality of
housing cavity receptacles formed therein, each housing cavity receptacle for
receiving a
corresponding shaft pin; and a plurality of torque transfer elements (TTEs),
each TTE providing
a curved TTE pin bearing surface and a TTE housing bearing surface; wherein
each housing
cavity receptacle provides a housing bearing surface; wherein a shaft pin and
a TTE are received
into each housing cavity receptacle such that within each housing cavity
receptacle, the shaft pin
bearing surface is received onto the TTE pin bearing surface and the TTE
housing bearing
surface opposes the housing bearing surface; wherein, responsive to misaligned
rotation of the
shaft centerline with respect to the housing centerline and regardless of
angular deflection of the
shaft centerline with respect to the housing centerline experienced within
each housing
receptacle during an articulated revolution of the shaft: (1) the shaft pins
are free to slidably
rotate about the TTEs; and (2) the TTE housing bearing surfaces are free to
slidably displace
against corresponding housing bearing surfaces.
[0036] The fourth aspect may include embodiments in which shaft pins further
provide a
convex shaft pin bearing surface thereon and TTEs provide a concave TTE pin
bearing surface.
[0037] The fourth aspect may also include embodiments in which the TTEs float
at least
generally parallel to an untilted shaft centerline when the TTE housing
bearing surfaces slidably
displace against corresponding housing bearing surfaces.
- 12 -
Date Recue/Date Received 2022-02-25
[0038] The fourth aspect may also include embodiments in which: each shaft pin
further
provides a shaft backlash surface; and each housing cavity receptacle further
provides a housing
backlash surface to oppose a corresponding shaft backlash surface; wherein the
transmission
further includes a backlash energizer assembly interposed between at least one
opposing shaft
backlash surface and housing backlash surface. In some embodiments, the
backlash energizer
assembly includes a puck. In some embodiments, the puck may separate a set
screw and a
Belleville washer. In some embodiments, the puck may include a laminate of
metal and
elastomer layers. In some embodiments, the backlash energizer assembly may
include a plate,
and in which the plate separates a set screw and a ball.
[0039] The fourth aspect may also include embodiments in which selected ones
of the TTE pin
bearing surfaces and the TTE housing bearing surfaces include a laminate. In
some
embodiments, the laminate may comprise metal and elastomer layers. In some
embodiments,
selected TTE pin bearing surfaces may include a hard facing. In some
embodiments, selected
TTE housing bearing surfaces may include curvature. In some embodiments,
selected TTE
housing bearing surfaces may include angled faces.
[0040] It is therefore a technical advantage of the disclosed laminated
bearings to extend the
service life of transmissions in which such laminated bearings are deployed.
As noted above,
relative sliding contact between bearing surfaces during torque transmission
is minimized and
ideally eliminated. Flex in the curved and flat laminate portions of the
torsional bearings takes
up and absorbs substantially all input/output shaft displacement due to shaft
misalignment. The
above-described disadvantages associated with galling and subsequent fretting
/ erosion of
metal-to-metal bearings are thus substantially reduced, if not eliminated
completely. Further,
"constant velocity" contact in the torsional bearing surfaces in CV
transmission style designs can
- 13 -
Date Recue/Date Received 2022-02-25
be maintained over a more sustained period via flex in the disclosed torsional
bearings, thereby
extending the service life of such CV-style transmission designs over a
conventionally expected
service life.
[0041] Another technical advantage of the disclosed transmission with
laminated bearings is
that flex in the laminated bearings (both torsional and spherical) maintains
design kinematics for
the transmission, promoting efficient torque transfer per design through all
torsional bearings
during service, and efficient transfer of thrust loads through the misaligned
input and output
transmission shafts.
[0042] Another technical advantage of the disclosed transmission with
laminated bearings is
that periodic maintenance and refurbishment of the transmission is optimized.
In prior designs
with metal-to-metal contact, fretting, erosion and other service wear on and
around the bearings
cause larger metal components also to become periodically no longer
serviceable, requiring their
refurbishment or replacement along with the bearings themselves. Such larger
metal
components (such as housings, splined connections, etc.) are often expensive
and time
consuming to repair and replace. Serious deterioration of such larger metal
components may
even require the entire transmission to be retired from service prematurely.
In the laminated
bearings transmission described in this disclosure, however, absent
extraordinary service events,
only the torsional bearings will require periodic replacement. The avoidance
of metal-to-metal
contact in the disclosed transmission with laminated bearings means that
larger metal
components in the input shaft adapter and the output shaft adapter should
remain substantially
less worn over an extended service life.
[0043] It is a technical advantage of the disclosed transmission with
unlaminated bearinngs to
enable transfer of high torque loads as compared to some conventional CV-ball
transmission
- 14 -
Date Recue/Date Received 2022-02-25
designs. Unlaminated bearings embodiments as set forth in this disclosure
preferably provide a
shaft with shaft pins formed integrally with the shaft on the shaft head. The
resulting one-piece
shaft head further transfers applied torque into unlaminated bearings at or
near the maximum
radius of the shaft head as received into the housing. In any proposed
transmission deployment,
the resulting potential for high torque load capability has to be weighed with
the kinematics of a
"bridge"-style bearings design as compared to conventional CV-ball
transmission designs. The
"bridge"-style design provides one less degree of freedom of movement in
articulated torque
transfer than can be offered by a CV-ball design. Also, the "bridge"-style
bearing itself is more
limited in its movement in housing pockets during articulated torque transfer
than in a
corresponding CV-ball design in that the "bridge"-style bearing is configured
to slide generally
longitudinally only relative to the shaft axis.
[0044] It is a further technical advantage of the disclosed transmission with
unlaminated
bearings to offer improved stability over conventional woodruff key designs.
The disclosed
designs have a comparatively longer circumferential aspect ratio at the shaft
head than
comparable woodruff key designs. The longer circumferential aspect ratio tends
to stabilize the
shaft better in the housing during misaligned rotation.
[0045] A further technical advantage of the disclosed "bridge"-style
transmissions (laminated
and unlaminated embodiments) is stability offered over comparable conventional
designs in
which the shaft pins are concave and the "bridge"-style bearings are convex.
The geometry of a
concave shaft pin is loaded along one of the long dimensions, resulting in
"thin strip" contact
area and a longer tilting "arm". The concave shaft pin design is thus more
likely to tilt and the
stress caused by contact loading on the thin strip contact area is high. In
contrast, convex shaft
pin embodiments according to the disclosed transmission designs are loaded
along the short
- 15 -
Date Recue/Date Received 2022-02-25
dimension, resulting in wider/larger contact area and shorter tilting arm. The
convex shaft pin
geometry thus allows the shaft pins to sit more stably in the housing
receptacles. The convex
shaft pins also tend to experience less stress since contact loading is on
wider contact surfaces
than provided on comparable concave shaft pins.
[0046] The foregoing has rather broadly outlined some features and technical
advantages of
the disclosed transmission designs, in order that the following detailed
description may be better
understood. Additional features and advantages of the disclosed technology may
be described.
It should be appreciated by those skilled in the art that the conception and
the specific
embodiments disclosed may be readily utilized as a basis for modifying or
designing other
structures for carrying out the same inventive purposes of the disclosed
technology, and that
these equivalent constructions do not depart from the spirit and scope of the
technology as
described.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] For a more complete understanding of the embodiments described in this
disclosure,
and their advantages, reference is made to the following detailed description
taken in conjunction
with the accompanying drawings, in which:
[0048] FIGURES lA through 12 illustrate various embodiments described in this
disclosure
including laminated torsional bearings, and in which further:
[0049] FIGURE lA is a perspective cutaway view of input shaft assembly 100
shown
operationally engaged with output shaft adapter 205;;
[0050] FIGURE 1B is a perspective view of output shaft assembly 200;
[0051] FIGURE 1C is a section as shown on FIGURE 1B;
- 16 -
Date Recue/Date Received 2022-02-25
[0052] FIGURE 2A is section view as shown on FIGURE 1A;
[0053] FIGURE 2B is an enlarged section view as shown on FIGURE 2A;
[0054] FIGURE 3 is a perspective view of a torsional bearing 300;
[0055] FIGURE 4 is an enlargement as shown on FIGURE 3;
[0056] FIGURE 5 is a perspective view of spherical bearing 350;
[0057] FIGURE 6 is a section as shown on FIGURE 5;
[0058] FIGURE 7 is an enlargement as shown on FIGURE 5;
[0059] FIGURE 8 is a partially exploded view of input shaft assembly 100 in
isolation;
[0060] FIGURE 9 is a partially exploded view of FIGURE lA (without the cutaway
on
FIGURE 1A);
[0061] FIGURE 10 is an elevation view of FIGURE lA (without the cutaway on
FIGURE
1A);
[0062] FIGURE 11 is a section as shown on FIGURE 10; and
[0063] FIGURE 12 is a modified version of FIGURE 11 showing transmission
misalignment.
[0064] FIGURES 13A through 20H illustrate various embodiments described in
this disclosure
including unlaminated embodiments with sliding contact between convex shaft
pins and concave
bearings surfaces, and in which further;
[0065] FIGURE 13A is a partial cutaway and exploded view of an exemplary
transmission
embodiment according to this disclosure in which upper housing assembly 1200U
is rotatably
connected to lower housing assembly 1200L via misaligned (articulated)
rotation of shaft
assembly 1100;
[0066] FIGURE 13B is a perspective view of lower housing 1205L on FIGURE 13A
in
isolation;
- 17 -
Date Recue/Date Received 2022-02-25
[0067] FIGURE 13C is a section as shown on FIGURE 13B;
[0068] FIGURE 14A is a section as shown on FIGURE 13A;
[0069] FIGURE 14B is a section as shown on FIGURE 14A;
[0070] FIGURE 15A illustrates Torque Transfer Element (TTE) 1300A, which for
reference is
the same TTE embodiment as TTE 1300 depicted on FIGURES 13A and 17;
[0071] FIGURES 15B through 15G illustrate TTEs 1300B through 1300G
respectively (in
which TTE 1300B through 1300G are alternative embodiments to TTE assembly
1300A on
FIGURE 15A);
[0072] FIGURE 16 is an enlargement as shown on FIGURE 15B;
[0073] FIGURE 17 is a fully exploded view of the exemplary transmission
embodiment shown
on FIGURE 13A;
[0074] FIGURE 18 is a further partial cutaway view of lower housing assembly
1200L as also
illustrated on FIGURE 13A;
[0075] FIGURE 19A is a section as shown on FIGURE 18;
[0076] FIGURES 19B and 19C are "faux section" views as shown FIGURE 19A,
depicting
shaft assembly 1100 substantially assembled at lower housing assembly 1200L
per FIGURES
13A, 14A and 14B, in which FIGURES 19B and 19C combine to schematically depict
articulation during misaligned rotation;
[0077] FIGURE 20A is a section similar to FIGURE 14A, except depicting an
alternative
embodiment including backlash energizer assembly 1400;
[0078] FIGURE 20B is an exploded view of backlash energizer assembly 1400 from
FIGURE
20A in isolation; and
- 18 -
Date Recue/Date Received 2022-02-25
[0079] FIGURES 20C and 20D, FIGURES 20E and 20F, and FIGURES 20G and 20H are
matched pairs of cutaway section views and corresponding exploded isolation
views of
alternative backlash energizer embodiments.
DETAILED DESCRIPTION
[0080] The following description of embodiments provides non-limiting
representative
examples using Figures, diagrams, schematics, flow charts, etc. with part
numbers and other
notation to describe features and teachings of different aspects of the
disclosed technology in
more detail. The embodiments described should be recognized as capable of
implementation
separately, or in combination, with other embodiments from the description of
the embodiments.
A person of ordinary skill in the art reviewing the description of embodiments
will be capable of
learning and understanding the different described aspects of the technology.
The description of
embodiments should facilitate understanding of the technology to such an
extent that other
implementations and embodiments, although not specifically covered but within
the
understanding of a person of skill in the art having read the description of
embodiments, would
be understood to be consistent with an application of the disclosed
technology.
[0081] Laminated Bearings Embodiments
[0082] Reference is now made to FIGURES lA through 12 in describing currently
preferred
transmission embodiments including laminated torsional bearings. For the
purposes of the
following disclosure, FIGURES lA through 12 should be viewed together. Any
part, item, or
feature that is identified by part number on one of FIGURES lA through 12 will
have the same
part number when illustrated on another of FIGURES 1A through 12. It will be
understood that
the embodiments as illustrated and described with respect to FIGURES lA
through 12 are
- 19 -
Date Recue/Date Received 2022-02-25
exemplary, and the scope of the inventive material set forth in this
disclosure is not limited to
such illustrated and described embodiments.
[0083] The scope of the inventive material set forth in this disclosure is
further not limited to
specific deployments of the described embodiments. For example, the following
description
directed to laminated embodiments makes reference to input shaft 101
operationally engaged
with output shaft 201 via connection of input shaft assembly 100 to output
shaft assembly 200.
It will be appreciated that in a typical BHA deployment, input shaft 101 may
be connected to the
rotor in a PDM, and output shaft 201 may be connected to the flex shaft / CV
joint above the
rotary bit. The description below is not limited to such an exemplary
deployment, however, and
for this reason input and output shafts 101 and 201 are referred to
generically throughout.
[0084] FIGURE lA is a perspective cutaway view of input shaft assembly 100
operationally
engaged with output shaft adapter 205 according to an exemplary embodiment of
the
transmission described in this disclosure. With momentary reference to FIGURE
8, and
continuing reference to FIGURE 1A, it will be seen that input shaft assembly
100 comprises
input shaft 101 conventionally connected to input shaft adapter 105 via, for
example a threaded
connection. Input shaft adapter 105 provides a plurality of shaped pins 107 on
a distal end
thereof.
[0085] With reference now to FIGURES 1B and 1C, output shaft assembly 200
comprises
output shaft 201 conventionally connected to output shaft adapter 205 via, for
example a
threaded connection. Output shaft adapter 205 provides a plurality of shaped
receptacles 207 in
an internal cylindrical recess 206. [Shaped receptacles 207 may also be
referred to as "notches'
in this disclosure.] Cylindrical recess 206 is formed on a distal end of
output shaft adapter 205.
With additional reference to FIGURES lA and 2A, for example, it will be seen
that cylindrical
- 20 -
Date Recue/Date Received 2022-02-25
recess 206 is provided in output shaft adapter 205 to receive input shaft
adapter 105. Further, as
shown on FIGURE 2A, and as will be described in detail further on this
disclosure, receptacles
207 / notches on output shaft adapter 205 are shaped to receive pins 107 on
input shaft adapter
105 when torsional bearings 300 are interposed between pins 107 and side walls
of receptacles
207. FIGURE 1C also depicts spherical bearing receptacle 209 formed on the
inside end of
cylindrical recess 206. As will be discussed in greater detail with reference
to FIGURES 5
through 7, spherical bearing receptacle 209 is shaped to receive spherical
bearing 350 illustrated
on, for example, FIGURES 1A, 5, 8 and 9.
[0086] With reference to FIGURE lA again, and with further reference to FIGURE
11, it will
be seen that the connection between input and output shaft adapters 105 and
205 is protected by
boot 210. Boot retainer 215 maintains and protects boot 210. Boot retainer 215
attaches to
output shaft adapter 215 via threads 217. Metal strap 214 maintains one end of
boot 210 in close
contact with input shaft adapter 105. Seal lip 212 holds the other end of boot
210 to output shaft
adapter 205. It will be therefore seen with reference to embodiments
illustrated on FIGURES lA
and 11 that boot retainer 215 has first and second boot retainer ends, the
first end towards input
shaft 101 and the second end towards output shaft adapter 205. Input shaft
adapter 105 has an
outer input shaft adapter periphery on the second end thereof (towards output
shaft adapter 205).
Output shaft adapter 205 has an outer output shaft adapter periphery on the
first end thereof
(towards input shaft 101). When the second end of input shaft adapter 105 is
received inside the
recess provided by spherical bearing receptacle 209 in output adapter shaft
205, boot retainer 215
is received over input shaft adapter 105 and output shaft adapter 205 such
that the first end of
boot retainer 215 is affixed to the outer input shaft adapter periphery and
the second end of boot
retainer 215 is affixed to the outer output shaft adapter periphery. [Refer to
description
- 21 -
Date Recue/Date Received 2022-02-25
immediately above associated with FIGURE 1C for further understanding of the
recess provided
by spherical bearing receptacle 209 in output adapter shaft 205].
[0087] FIGURE 2A is a section as shown on FIGURE 1A. When torque is provided
to rotate
input shaft adapter 105 in the direction of arrow T, input shaft adapter 105
engages torsional
bearings 300 onto the side walls of the receptacles 207 provided in output
shaft adapter 205.
Torques is thus transferred to output shaft adapter 205.
[0088] While the embodiment illustrated on FIGURE 2A has six (6) torsional
bearings 300, it
will be appreciated that this number is exemplary only. The scope of this
disclosure is not
limited as to the number of torsional bearings provided in any embodiment. The
number will be
determined by user design factors such as, without limitation, size of input
and output shafts 101
and 201, and amounts of torque to be transferred in view of stress performance
of various
constructions of torsional bearings 300. FIGURES 2A and 2B also depict that in
some
embodiments, adhesive bonding 318 may be provided between some or all of the
flat laminate
portions 320 of torsional bearings 300 and the shaped receptacles / "notches"
207 on output shaft
adapter 205 (although the scope of this disclosure is not limited in this
regard). Refer to
description below associated with FIGURE 3 for further understanding of flat
laminate portions
320.
[0089] FIGURE 2B is a section as shown on FIGURE 2A. FIGURE 2B shows that the
engagement of torsional bearings 300 by input shaft adapter 105 is via curved
portions of pins
107. With momentary reference to FIGURE 3 (in which an exemplary torsional
bearing 300 is
depicted in more detail), it will be seen that the curved portions of pins 107
engage curved
laminate portions 310 of torsional bearings 300. Returning now to embodiments
illustrated on
FIGURE 2B, it will be seen that in some embodiments, adhesive bonding 317 may
be provided
- 22 -
Date Recue/Date Received 2022-02-25
between some or all of the curved portions of pins 107 and the curved laminate
portions 310 of
torsional bearings 300 (although the scope of this disclosure in not limited
in this regard). Also,
with further reference to FIGURE 2B, it will be seen that torsional bearing
300 has a midpoint
330 which coincides with a corresponding midpoint on selected pins 107. As
shown on FIGURE
2B, the curved portions on said selected pins 107 each have a radius 111 whose
centerpoint 113
coincides with the midpoint 330.
[0090] With further reference now to FIGURE 2A and 2B, it will be appreciated
that in
currently preferred embodiments, the geometries illustrated are designed so
that the maximum
pin nose diameters 109 on pins 107 are on a locus 409 whose diameter coincides
with the
external diameter of output shaft 201 (such external diameter also illustrated
on FIGURE 2A as
dotted line 409). In this way, in such currently preferred embodiments, torque
is directly
transferred through the full cross-section of output shaft 201, substantially
unifying the torque
stress gradients across output shaft 201 near the connection with output shaft
adapter 205. It will
nonetheless be appreciated, however, that the scope of this disclosure is not
limited to
deployments in which locus 409 of maximum pin nose diameters 109 coincides
with the external
diameter of output shaft 201.
[0091] FIGURE 3 is a perspective view of a currently preferred embodiment of a
torsional
bearing 300 (also shown in situ on, for example, FIGURES 1A, 2A and 2B).
Torsional bearings
300 are shaped to be received in an interposed relationship between pins 107
on input shaft
adapter 105, and the side walls of receptacles 207 on output shaft adapter
205. In this interposed
relationship, pins 107 contact a curved laminate portion 310 on torsional
bearings 300. Curved
laminate portion 310 is described in more detail below with reference to
FIGURE 4. The side
- 23 -
Date Recue/Date Received 2022-02-25
walls of receptacles 207 contact a flat laminate portion 320 on torsional
bearings 300. Curved
laminate portion 310 and flat laminate portion 320 are separated by metal
portion 302.
[0092] FIGURE 4 is an enlargement as shown on FIGURE 3. FIGURE 4 illustrates
curved
laminate portion comprising alternating metal layers 312 and rubber layer 314.
Although
FIGURES 3 and 4 have been illustrated with a metal layer 312 as the immediate
contact interface
with pins 107 on input shaft adapter 105, this disclosure is not limited in
this regard. Other
embodiments may provide a rubber layer 314 as the immediate contact interface
with pins 107.
It has been found advantageous to provide a rubber layer 314 as the immediate
contact interface
with pins 107 in deployments where adhesive is used to adhere torsional
bearings 300 to pins
107 during assembly.
[0093] Referring particularly to rubber layers 314 on FIGURE 4, each rubber
layer 314 is
preferably less than 0.030" thick, and more preferably in the range of 0.015
to 0.002" thick, in
order to maintain a beneficial compressive stress field throughout nearly the
entire rubber layer
during service. Although the scope of this disclosure is not limited to
particular thicknesses of
rubber layers 314, it has been found that thicknesses in the above guidelines
tend to reduce the
tendency of the rubber to extrude from the edge of curved laminate portion 310
when placed
under load (compression, shear and some bending). The preferred layer
thicknesses for rubber
layer 314 may be obtained by highly precise calendaring operations during
manufacture, using
extremely stiff rolling cylinders to extrude the strip form of uncured "green"
rubber. The
preferred layer thicknesses may also be obtained by extrusion through a highly
accurate and
sharp strip die. The strip of "green" rubber may also be cured or semi-cured
in the strip form
prior to bearing assembly. This may be accomplished with an oven, autoclave or
microwave
- 24 -
Date Recue/Date Received 2022-02-25
heating. A microwave heating source is more preferred and can offer a
continuous cure cycle.
The strip may be cut to size and assembled into layers with the metal
components.
[0094] Currently preferred embodiments customize rubber material selections
for rubber layers
314. The selection of material for rubber layer will also dictate the exact
preferred method of
forming rubber layer 314 and bonding them to metal surfaces such as on metal
layers 312. A
high temperature rubber material such as fluorinated silicone rubber (FSR) is
advantageous for
extended use in transmissions whose service includes elevated bottom hole
temperatures. In
other embodiments, rubber material selections may be made from, for example,
natural rubber
(NR), nitrile butadiene rubber (NBR), hydrogenated nitrile butadiene rubber
(HNBR),
fluoroelastomers (FKM), perfluoroelastomers (FFKM), or ethylene propylene
diene monomer
(EPDM) rubber formulations.
[0095] Referring now to metal layers 312 on FIGURE 4, each metal layer 312 is
preferably a
high strength carbon alloy steel or stainless steel, preferably with a yield
strength in a range of
140 ksi to 230 ksi (higher strengths preferred for highly stressed metal
layers 312). Metal layer
thicknesses are preferably in a range of 0.001" to 0.030", and more preferably
in a range of
0.002" to 0.015", although this disclosure is not limited in this regard.
Further, the ratio of
thicknesses of rubber layers 314 to metal layers 312 within curved laminate
portion 310 is
preferably in a range of 1.0 to 2.0, although again this disclosure is not
limited in this regard. A
currently preferred embodiment of curved laminate portion 310 has rubber
layers 314 that are
0.002" thick, and metal layers 312 that are 0.002" thick.
[0096] Preferred thicknesses of metal layers 312 may be initially obtained
from sheet rolling
operations or thin film deposition techniques. Final forming of the metal
layers 312 may be
accomplished pressing with a suitable die. Metal layers 312 having thicknesses
in the above
- 25 -
Date Recue/Date Received 2022-02-25
preferred ranges will typically take the form of high strength foils. Examples
of commercially
available high strength foils that may be used for metal layers 312 include
Integran Armor Foil,
Integran Nickel-Cobalt Nano Foil, as well as traditional high-strength, heat-
treated stainless steel
301 or 420 grade foil, all available from specialty suppliers such as Nikken
Steel, Comet Metals,
or Ulbrich Stainless Steels for example.
[0097] Curved laminate portion 310 on FIGURE 4 may be formed by any
conventional
method, such as pressing metal layers 312 and rubber layers 314 together at
elevated
temperatures, and/or by bonding metal layers 312 and rubber layers 314
together with a suitable
adhesive. Suitable conventional high temperature adhesives are commercially
available from
suppliers such as Cilbond, Lord (Chemlok brand), and Dow Chemicals (Thixon and
Megum
brands). A suitable adhesive product may be chosen to suit the characteristics
of the
rubber/elastomeric material selected for rubber layers 314. For example,
Chemlok 607 is a
suitable adhesive for FSR material, while Chemlok 207 primer and Chemlok 6450
top coat is a
suitable adhesive for NBR or HNBR. Optimized chemical formulas for such
products coincide
with the polymer families and compounding mixtures typically found for each
category of
rubber/elastomer material. The consistency of the adhesive bonding is
optimized through
heating and pressing steps in manufacture.
[0098] As noted above, curved laminate portion 310 on FIGURES 3 and 4 is
shaped to mate
with pins 107 on input shaft adapter 105. A series of conventional cylindrical
press dies may be
used to shape metal layers 314 to the designed curvatures. Dies with less
curvature must be used
for metal layers 314 further away from the interface with pins 107 in order to
maintain an overall
uniform radial thickness of the finished curved laminate portion 310. The
total overall radial
thickness of finished curved laminate portion 310 will advantageously be
optimized for the
- 26 -
Date Recue/Date Received 2022-02-25
operating parameters of the transmission being designed. However, it is
expected that curved
laminate portions 310 deployed in many applications will have overall radial
thicknesses in a
range from 0.030" to 0.250".
[0099] Construction of curved laminate portion 310 is conventional. Calendared
rubber layers
314, in strip form, are interposed between calendared metal layers 312, each
rubber layer 314
having initially been cut to a suitable length and width to cover the
interface between each
adjacent metal layer 312. The length of rubber layers 314 may be the same or
slightly longer
than the arc length of the adjacent metal layers 312. The assembled metal and
rubber layers 312
and 314 may be held together with adhesive, if desired, and then placed into a
forming mold. An
adhesive may be particularly desirable if rubber layers 314 were pre-cured
prior to assembly.
The assembly is then heated and cured in the mold, under pressure, to activate
the final rubber
curing and bonding reactions of the rubber and adhesive systems.
[00100] Referring now to FIGURE 3, torsional bearing 300 also provides flat
laminate portion
320. As noted above, torsional bearings 300 are shaped to be received in an
interposed
relationship between pins 107 on input shaft adapter 105, and the side walls
of receptacles 207
on output shaft adapter 205. In this interposed relationship, the side walls
of receptacles 207
contact flat laminate portion 320. It will be appreciated from FIGURE 3 that
flat laminate
portion 320 is comprised of metal layers and rubber layers similar to metal
layers 312 and rubber
layers 314 within curved laminate portion 310.
[00101] The disclosure immediately above describing currently preferred
materials and
construction of curved laminate portion 310 applies similarly to the
corresponding currently
preferred materials and construction of flat laminate 320. Rectangular metal
layers can be cut
from metal foils using cutting dies, laser or other conventional foil cutting
techniques.
- 27 -
Date Recue/Date Received 2022-02-25
Calendared rubber in strip form is cut to size to give optimum coverage and
overlap of the metal
layers. An adhesive may be used to assemble alternating rubber and metal
layers. The assembly
is loaded into a mold and cured under heat and pressure.
[00102] Regarding thicknesses in flat laminate 320, the disclosure above
describing currently
preferred thicknesses of metal layers 312 and rubber layers 314 in curved
laminate portion 310
applies equally to the currently preferred thicknesses of corresponding metal
and rubber layers in
flat laminate 320. As to overall laminate thickness of flat laminate 310,
thicknesses in the range
of 0.020" to 0.250" are preferred, although the scope of this disclosure is
not limited in this
regard.
[00103] Referring again to FIGURE 3, metal portion 302 on torsional bearing
300 separates
curved laminate portion 310 and flat laminate portion 320. Metal portion 302
is made from a
conventional high strength plain carbon steel such as high strength grade
4340, or a high strength
low alloy steel such as 300M. Alternatively, a high strength martensitic alloy
steel may be used,
such as Aermet 100.
[00104] It will be seen from FIGURES 3 and 2A that the side elevation of
torsional bearing 300
is shaped to be received into output shaft adapter receptacles 207 by virtue
of a generally
asymmetric trapezoidal profile that includes flat laminate portion 320. Such
asymmetric
trapezoidal profile achieves several advantages, including (1) maximizing the
cross-sectional
area of flat laminate portion 320 so as to transmit and distribute torque
through torsional bearing
300 with reduced compressive stress and shear stress on the materials in the
construction of flat
laminate portion 320, and (2) creating a self-immobilizing "dovetail" shape
when retained in
output shaft adapter receptacles 207 by input shaft adapter pins 107 (see
FIGURES 2A and 2B).
- 28 -
Date Recue/Date Received 2022-02-25
[00105] As noted above in the "Summary" section, and with reference to FIGURES
lA and 1B,
even though the input shaft 101 and output shaft 201 are misaligned in
service, there is no
relative movement during torque transmission between (1) contact surfaces
between pins 107
and curved laminate portions 310, and (2) contact surfaces between flat
laminate portions 320
and receptacles 207. Flex in the curved and flat laminate portions 310 and 320
of torsional
bearings 300 takes up and absorbs substantially all relative displacement of
input shaft 101 and
output shaft 201 due to shaft misalignment. To that end, embodiments may
provide curved and
flat laminate portions 310 and 320 that are bonded with adhesive to their
corresponding bearing
surfaces on pins 107 and receptacles 207. Suitable adhesives are described
above in the
discussion of the construction of torsional bearings 300.
[00106] FIGURE 5 is a perspective view of spherical bearing 350. With
momentary reference
to FIGURES lA through 1C, it will be seen that spherical bearing 350 acts as
thrust bearing,
absorbing compressive and shear forces at the point at which the tip of input
shaft adapter 105
contacts output shaft adapter 205 inside cylindrical recess 206. Spherical
bearing receptacle 209
is provided inside output shaft adapter 205, and is positioned and shaped to
mate with spherical
bearing 350 when input shaft adapter pins 107 and torsional bearings 300 are
fully received and
operationally engaged within output shaft adapter receptacles 207.
[00107] FIGURE 5 depicts spherical bearing 350 as a dome-shaped laminate of
alternating
metal and rubber layers. More colloquially, preferred embodiments of spherical
bearing 350
have a general "contact lens" shape. With momentary reference to FIGURES lA
and 1B, for
example, spherical bearing 350 allows a large thrust load to be transmitted
through from input
shaft assembly 100 to output shaft assembly 200 while also allowing a small
angle of deflection.
- 29 -
Date Recue/Date Received 2022-02-25
It will be appreciated that spherical bearing 350 obviates metal-to-metal
contact between the tip
of input shaft adapter 105 and output shaft adapter 250 responsive to the
thrust load.
[00108] Spherical bearing 350 is similar in materials and construction to
curved and flat
laminate portions 310 and 320 on torsional bearings 300, as described above.
FIGURE 6 is a
section as shown on FIGURE 5, and illustrates preferred embodiments of
spherical bearing 350
to be of substantially uniform laminate thickness. FIGURE 7 is an enlargement
as shown on
FIGURE 5, and depicts spherical bearing 350 to comprise alternating metal
layers 352 and
rubber layers 354. As described above with respect to metal layers 312 and
rubber layers 314 on
torsional bearings 300, FIGURE 7 depicts a metal layer 352 as the immediate
contact interface
with input shaft adapter 105 on one side, and with spherical bearing
receptacle 209 on the other
side. Other embodiments may provide a rubber layer 354 as the immediate
contact interface on
either or both sides. It has been found advantageous to provide rubber layer
314 as the
immediate contact interface with pins 107 in deployments where adhesive is
used to adhere
spherical bearing 350 to input shaft adapter 105 and/or spherical bearing
receptacle 209 during
assembly.
[00109] Currently preferred embodiments of individual metal layers 352 and
rubber layers 354
on spherical bearing 350 may preferably have individual thicknesses consistent
with the
thickness ranges described above with respect to metal layers 312 and rubber
layers 314 on
torsional bearings 300, although the scope of this disclosure is not limited
in this regard.
Currently preferred embodiments of overall laminate thicknesses of spherical
bearing 350 are in
the range of 0.040" to 0.500".
[00110] Currently preferred embodiments of individual metal layers 352 and
rubber layers 354
on spherical bearing 350 may preferably be made of materials consistent with
the materials and
- 30 -
Date Recue/Date Received 2022-02-25
constructions described above with respect to metal layers 312 and rubber
layers 314 on torsional
bearings 300, although the scope of this disclosure is not limited in this
regard. In currently
preferred embodiments, fabrication of spherical bearings 350 utilizes a series
of spherical dies
where each individual metal layer 352 is pressed to a custom curvature in
register with its
neighboring metal layers 352, so that a uniform thickness of rubber layers 354
and a constant
overall thickness can be maintained throughout spherical bearings 350. Rubber
layers 354 can
be pre-formed in a die press with suitable spherical curvature, or cut to a
geometrical shape that
avoids overlapping material folds during assembly.
1001111 It will be appreciated that similar to the discussion above with
respect to torsional
bearings 300, and with reference to FIGURES lA and 1B, there is no relative
movement during
torque transmission between (1) contact surfaces between the tip of input
shaft adapter 105 and
spherical bearing 350, and (2) contact surfaces between spherical bearing 350
and spherical
bearing receptacle 209, even though the input shaft 101 and output shaft 201
are misaligned in
service. Flex in spherical bearing 350 takes up and absorbs substantially all
relative
displacement of input shaft 101 and output shaft 201 due to shaft misalignment
and/or thrust load
during service. To that end, embodiments may provide a spherical bearing 350
that is bonded
with adhesive to its corresponding bearing surfaces on the tip of input shaft
adapter 105 and
spherical bearing receptacle 209. Suitable adhesives are described above in
the discussion of the
construction of torsional bearings 300.
[00112] FIGURE 8 is a partially exploded view of input shaft assembly 100,
torsional bearings
300 and spherical bearing 350 immediately before (with reference to FIGURE 1A)
insertion into
output shaft adapter 205 during assembly.
-31 -
Date Recue/Date Received 2022-02-25
[00113] FIGURE 9 is a partially exploded view of FIGURE lA (without the cutout
shown on
FIGURE 1A). FIGURE 10 is an elevation view of FIGURE lA (without the cutout
shown on
FIGURE 1A). FIGURE 11 is a section as shown on FIGURE 10, and FIGURE 12 is a
modified
version of FIGURE 11 showing transmission misalignment.
[00114] FIGURES 9 and 11 are useful to describe aspects of currently preferred
assembly
methods of the components shown on FIGURES lA through 1C (and FIGURES 9 and
11). Boot
retainer 215 and boot 214 are received over input shaft adapter 105. Note the
smallest inside
diameter of boot retainer 215 should be greater than max pin nose diameter 109
in order for boot
retainer 215 to slide over. Boot retainer 215 and boot 210 are then moved
temporarily
down/along input shaft 101 while assembly continues. Alternatively, boot
retainer 215 may be
provided in two halves and assembled over input shaft 101 if the smallest
inside diameter of boot
retainer 215 is designed to be less than max pin nose diameter 109. Adhesive
is applied as
desired to the bearing surfaces of pins 107, curved laminate portions 310 of
torsional bearings
300, receptacles 207, flat laminate portions 320 of torsional bearings 300,
tip of input shaft
adapter 105, spherical bearing 350 and spherical bearing receptacle 209. Input
shaft assembly
100 is assembled (refer FIGURE 8) and inserted into output shaft assembly 200.
Pressure is
applied before heating the assembled pieces to 300 deg F for 30 ¨ 90 mins to
cure the adhesive.
[00115] With reference now to FIGURES lA though 1C and FIGURES 9 and 11 again,
boot
210 and boot retainer 215 are slid into position where seal lip 212 locks into
its groove on boot
retainer 215 and metal strap 214 is tightened down to hold boot 210 to input
shaft adapter 105.
Boot retainer 215 is screwed down onto output shaft adapter 205 via threads
217. It will be
appreciated from FIGURE 11 that when fully screwed down, boot retainer 215
forces the distal
end of boot 210 (near seal lip 212) onto input shaft adapter 105. A suitable
adhesive and/or an
- 32 -
Date Recue/Date Received 2022-02-25
additional metal strap may also be used to secure the distal end of boot 210
to input shaft adapter
105. A suitable adhesive may also be applied to secure seal lip 212 to boot
retainer 215.
[00116] FIGURE 11 also illustrates radius "r" of spherical bearing 350. In
currently preferred
embodiments, "r" is selected to have a center point that coincides with the
midpoint of pins 107
as deployed on input shaft adapter 105. FIGURE 11 further illustrates fill
port 221 and evacuate
port 223 for lubricant in alternative embodiments in which input shaft
assembly 100 and output
shaft assembly are a sealed unit. See discussion of "variations" immediately
below regarding
such sealed unit embodiments. It will be therefore seen with reference to
embodiments
illustrated on FIGURE 11 that output shaft adapter 205 has an outer output
shaft adapter
periphery on the first end thereof (towards input shaft 101). Fill port 221
connects the outer
output shaft adapter periphery to the recess provided by spherical bearing
receptacle 209 in
output adapter shaft 205. [Refer to description above associated with FIGURE
1C for further
understanding of the recess provided by spherical bearing receptacle 209 in
output adapter shaft
205.] Evacuate port 223 also connects the outer output shaft adapter periphery
to the recess
provided by spherical bearing receptacle 209 in output adapter shaft 205. Fill
port 221 and
evacuate port 223 may be sealed as required with suitable tapered pipe plugs.
Evacuate port 223
may be used in conjunction with a conventional vacuum pump: (1) during filling
through fill port
221, to evacuate lubricant chamber in order to vacuum-assist distribution of
lubricant throughout
the chamber, and (2) to remove lubricant from throughout the chamber during
lubricant purge.
FIGURE 11 further illustrates that in some embodiments, adhesive bonding 357,
358 may be
provided between at least one of: (1) the laminate portion of spherical
bearing 350 and the tip
provided by shaft adapter 105; and/or (2) the laminate portion of spherical
bearing 350 and the
- 33 -
Date Recue/Date Received 2022-02-25
recess provided by spherical bearing receptacle 209 in output adapter shaft
205 (although the
scope of this disclosure is not limited in either of these regards).
[00117] FIGURE 12 illustrates the flex of torsional bearings 300 and spherical
bearing 350
during transmission misalignment.
[00118] Variations on Laminated Bearings Embodiments
[00119] Currently preferred embodiments envisage three (3) to eight (8)
torsional bearings 300
equally spaced around input shaft adapter 105. This disclosure is not limited
in this regard,
however, and any number of bearings could be deployed. Within currently
preferred
embodiments, four (4) to eight (8) pins are more preferred, with four (4) to
six (6) pins used on
4.75" to 6.75" shaft sizes, and eight (8) pins used on larger sizes.
[00120] Embodiments of the disclosed transmission may run as a sealed assembly
with grease
or oil lubrication. Refer to disclosure above with reference to FIGURE 11.
Because the internal
components in the laminated bearings embodiments described herein are
configured to avoid
metal-to-metal sliding contact, however, other embodiments may be left
unsealed, and may be
further optimized for mud compatibility in such unsealed state.
[00121] Embodiments of the disclosed transmission may be combined with several
types of
thrust and tension socket devices to control the thrust load of the rotor. The
scope of this
disclosure is not limited in this regard. For example, and without limitation,
a thrust surface and
tension rod coupling could be provided instead of the spherical bearing 350 as
received into
spherical bearing receptacle 209 as described above.
[00122] Embodiments of the disclosed torsional bearings 300 may also be
combined with other,
alternative transmission designs transmitting torque between misaligned or
angularly displaced
shafts, such as, for example, universal joint designs, CV joint designs, claw
joint designs or
- 34 -
Date Recue/Date Received 2022-02-25
knuckle joint designs. Deployment of embodiments of the disclosed torsional
bearings 300 on
such alternative transmission design may provide advantages as described above
in this
disclosure, including improving the operational torque transfer efficiency and
life cycle in such
alterative designs.
[00123] In particular, without limiting the preceding paragraph, the double
knuckle transmission
coupling disclosed in U.S. Published Patent Application 2017/0045090
(applicant Lord
Corporation of Cary, North Carolina, U.S.A) is considered highly suitable for
modification to
include embodiments of torsional bearings 300 as described in this disclosure.
In this regard, the
following Figures and paragraphs of the written specification of 2017/0045090
are incorporated
into this disclosure by reference as if fully set forth herein: (1) Figures 2
through 21B of
2017/0045090; and (2) paragraphs 0004 through 0028, paragraphs 0038 through
0050, and
paragraphs 0053 and 0054 of 2017/0045090.
[00124] For example, referring to Figures 6, 7, 8, 9, 11 and 12 in
2017/0045090 and associated
narrative, the interfaces between couple center element 404 and input yoke 402
/ output yoke 406
may be adapted to receive embodiments of torsional bearings 300 as described
in this disclosure.
In more detail, arcuate recesses 432 on input yoke 402 and arcuate recesses
443 on output yoke
406 in 2017/0045090 may be adapted to provide shaped receptacles, and then
torsional bearings
300 may be provided in such shaped receptacles. The curvatures on curved
laminate portions
312 on torsional bearings 300 (referring to FIGURE 3 herein) may preferably be
selected to
match corresponding curvatures on arcuate recesses 432, 443 on input yoke 402
/ output yoke
406 in 2017/0045090. Knuckles 411 on couple center element 404 will then bear
on curved
laminate portions 312 of torsional bearing 300 (referring to FIGURE 3 herein)
when input yoke
402, output yoke 406 and couple center element 404 are assembled. Resilient
bearing contact
- 35 -
Date Recue/Date Received 2022-02-25
could thereby be provided at the interfaces between couple center element 404
and input yoke
402 / output yoke 406. Such an adaptation may thus provide many of the same
advantages
described above in this disclosure to the double knuckle coupling described in
2017/0045090.
Further, the shaped receptacles provided in arcuate recesses 432, 443 in
2017/0045090 may
receive torsional bearings 300 snugly such that flat laminate portions 320 on
torsional bearings
300 (again referring to FIGURE 3 herein) provide further resilient bearing
contact between
couple center element 404 and input yoke 402 / output yoke 406.
[00125] Alternatively and/or additionally, laminated bearings may be provided
at torque transfer
interfaces between faces 416 on couple center element 404 in 2017/0045090 when
couple center
element 404 is received within slots 436, 439 on input yoke 402 / output yoke
406.
[00126] Some embodiments of the adaptation described in the preceding
paragraph (hereafter,
"double knuckle coupling adaptation") may have contact surfaces adhesively
bonded as
described above in this disclosure. Some embodiments of the double knuckle
coupling
adaptation may be open to mud flow, and others may be protected from mud flow.
Some
embodiments of torsional bearings 300 deployed in the double knuckle coupling
adaptation may
have curved faces provided thereon, so that when received in the shaped
receptacles, torsional
bearings 300 are flush with the outer surfaces of input yoke 402 and output
yoke 406. In some
embodiments of the double knuckle coupling adaptation, torsional bearings 300
may be provided
in all occurrences of the interfaces between couple center element 404 and
input yoke 402 /
output yoke 406. In other embodiments, torsional bearings 300 may be provided
in selected ones
of such interfaces.
[00127] Unlaminated bearings embodiments
- 36 -
Date Recue/Date Received 2022-02-25
[00128] The scope of this disclosure is not limited to laminated bearings
embodiments such as
torsional bearings 300 and spherical bearings 350 described above with
reference to FIGURES 1
through 12. Selected bearings may be unlaminated (or "monolithic") bearings.
Selected
unlaminated bearing materials could also include, without limitation, polymer,
plastic or metals.
Preferably, unlaminated bearings described in this disclosure have the
"bridge"-style shape.
However, selected unlaminated bearing shapes could also include, without
limitation, flat,
spherical, cylindrical or chevron shapes.
[00129] The unlaminated bearings embodiments described below with reference to
FIGURES
13A and 20A are referred to as "Torque Transfer Elements" (TTEs) in order to
provide a
different nomenclature in this disclosure from the laminated bearings
embodiments described
above with reference to FIGURES 1 through 12. As described above, laminations
in laminated
bearings embodiments (such as torsional bearings 300 and spherical bearings
350 on FIGURES
1 through 12) are disposed to "flex" during misaligned (articulated) shaft
rotation. By contrast,
unlaminated bearings (or TTEs), embodiments of which are described below with
reference to
FIGURES 13A though 20H, are disposed to slide and displace within pockets (or
"housing
cavity receptacles") provided in the internal periphery of the housing in
which the articulating
shaft is received. As the shaft "tilts" about its untilted axial centerline
during misaligned
(articulated) rotation, curved bearing surfaces on shaft pins slidably rotate
against corresponding
curved bearings surfaces on the TTEs as received in the housing cavity
receptacles. Further,
substantially flat surfaces on the TTEs are disposed to slidably displace
against corresponding
bearing surfaces on the housing cavity receptacles as the shaft tilts and the
curved bearing
surfaces on the shaft pins slidably rotate against curved bearing surfaces on
the TTEs. The
sliding displacement of TTEs with respect to the housing cavity receptacles
during articulated
- 37 -
Date Recue/Date Received 2022-02-25
rotation is in a direction generally parallel to the shaft's untilted axial
centerline. Preferably, the
curved bearing surfaces on the shaft pins are convex, and the curved bearing
surfaces on the
TTEs are concave, although the scope of this disclosure is not limited in this
regard.
[00130] Reference is now made to FIGURES 13A through 20H in describing
currently
preferred transmission embodiments including unlaminated torsional bearings.
For the purposes
of the following disclosure, FIGURES 13A through 20H should be viewed
together. Any part,
item, or feature that is identified by part number on one of FIGURES 13A
through 20H will have
the same part number when illustrated on another of FIGURES 13A through 20H.
It will be
understood that the embodiments as illustrated and described with respect to
FIGURES 13A
through 20H are exemplary, and the scope of the inventive material set forth
in this disclosure is
not limited to such illustrated and described embodiments.
[00131] As noted above, the scope of the inventive material set forth in this
disclosure is not
limited to specific deployments of the described embodiments. For example, the
following
description directed to unlaminated embodiments makes reference to upper and
lower housing
assemblies 1200U, 1200L each operationally engaged with shaft assembly 1100 at
opposing
ends thereof. These embodiments reflect a typical BHA deployment. The
description below is
not limited to such an exemplary deployment, however.
[00132] FIGURE 13A is a partial cutaway and exploded view of an exemplary
transmission
embodiment according to this disclosure in which upper housing assembly 1200U
is rotatably
connected to lower housing assembly 1200L via misaligned (articulated)
rotation of shaft
assembly 1100. FIGURE 17 is a fully exploded view of the transmission
embodiment shown on
FIGURE 13A. Generally on FIGURES 13A and 17, applied torque is shown
transmitted from
upper housing assembly 1200U into shaft assembly 1100, and then into lower
housing assembly
- 38 -
Date Recue/Date Received 2022-02-25
1200L. A general convention is followed throughout the embodiments illustrated
on FIGURES
13A through 20H, in which applied torque is disposed to follow shaft rotation
in a clockwise
direction looking downhole from an illustrated "high side" (see notation near
upper housing
assembly 1200U on FIGURES 13A and 17) to an illustrated "low side" (see
notation near lower
housing assembly 1200L). This convention follows the generally accepted
subterranean drilling
convention of "clockwise rotation looking downhole". In particular, this
convention follows the
general convention of configuring the rotor of a positive displacement motor
("PDM" or "mud
motor") to rotate a shaft in a clockwise direction looking downhole.
[00133] It will be understood, however, that the scope of this disclosure is
not limited to
embodiments following the "clockwise rotation looking downhole" convention for
rotation and
torque. Alternative embodiments, not illustrated, configured to transmit
applied torque in a
counterclockwise direction looking downhole are within the scope of this
disclosure. Persons of
ordinary skill in this art will require very little experimentation to adapt
the embodiments
illustrated on FIGURES 13A through 20H of this disclosure to transfer applied
torque in the
opposite direction from the direction illustrated. In many cases, it will
require no more than
reversing orientations of illustrated components or creating "mirror images"
of illustrated
assemblies.
[00134] FIGURES 13A and 17 should be viewed together for a more detailed
understanding of
applied torque transmission from upper housing assembly 1200U into shaft
assembly 1100, and
then into lower housing assembly 1200L. Upper housing assembly 1200U includes
upper
housing 1205U, which in turn includes upper housing threads 1201U provided on
one end
thereof. Upper housing threads 1201U are preferably configured to mate with an
adapter
ultimately connected rotatably to a PDM rotor, although the scope of this
disclosure is not
- 39 -
Date Recue/Date Received 2022-02-25
limited any particular component with which upper housing threads 1201U may be
configured to
mate. Shaft rotation direction R on FIGURES 13A and 17 illustrates clockwise
rotation of upper
housing assembly 1200U looking downhole, consistent with the corresponding
general
convention of configuring a PDM rotor to rotate clockwise looking downhole, as
described
above.
[00135] Lower housing assembly 1200L includes lower housing 1205L, which in
turn includes
lower housing threads 1201L provided on one end thereof. Lower housing threads
1201L are
preferably configured to mate with a motor bearing mandrel or drive shaft
ultimately connected
to a rotary bit, although the scope of this disclosure is not limited any
particular component with
which lower housing threads 1201L may be configured to mate. Shaft rotation
direction R on
FIGURES 13A and 17 further illustrates clockwise rotation of lower housing
assembly 1200L
looking downhole, consistent with the corresponding general convention of
configuring a PDM
rotor to rotate clockwise looking downhole, as described above.
[00136] FIGURES 13A and 17 show upper and lower housings 1205U, 1205L as
hollow, with
internal receptacles and surfaces formed therein according to Figures and
detailed description set
forth below. FIGURES 13A and 17 further show that shaft assembly 1100 provides
a shaft head
1102 at each end of shaft 1101. As will be described in more detail further
below, each shaft
head 1102 is configured to be received into a corresponding one of upper and
lower housings
1205U, 1205L and, when received therein, to interface with receptacles and
surfaces formed
internally on upper and lower housings 1205U, 1205L. As seen on FIGURES 13A
and 17, each
shaft head 1102 provides a preselected number of shaft pins 1106. Shaft pins
1106 are
preferably spaced equally in radial disposition around shaft head 1102,
although the scope of this
disclosure is not limited to equi-spaced radial disposition. Five (5) shaft
pins 1106 are provided
-40 -
Date Recue/Date Received 2022-02-25
on each shaft head 1102 in the embodiments illustrated on FIGURES 13A through
20H,
although again the scope of this disclosure is not limited to any particular
number of shaft pins
1106 per shaft head 1102. Other embodiments (not illustrated) may provide
shaft heads with
other numbers of shaft pins, and/or with other than equi-spaced radial
disposition. Other
embodiments (not illustrated) may also provide a number and spacing
configuration of shaft pins
on a shaft head at one end of a shaft that differs from the number and spacing
configuration of
shaft pins at the other end of the shaft.
[00137] FIGURE 17 illustrates each shaft pin 1106 preferably providing a
curved shaft pin
bearing surface 1109 and a shaft backlash surface 1105. The curved shaft pin
bearing surface
1109 on one shaft pin 1106 generally faces the shaft backlash surface 1105 of
a neighboring
shaft pin 1106.
[00138] FIGURES 13A and 17 further illustrate Torque Transfer Elements
("TTEs") 1300
interposed between shaft pins 1106 and upper and lower housings 1205U, 1205L
when shaft
heads 1102 are received into upper and lower housings 1205U, 1205L.
Preferably, one (1) TTE
1300 is provided for each shaft pin 1106, as depicted in the embodiments
illustrated throughout
FIGURES 13A through 20H in this disclosure. It will nonetheless be appreciated
that the scope
of this disclosure is not limited in this regard, and other embodiments may
provide some shaft
pins without TTEs, or some shaft pins with laminated torsional bearings
(embodiments of which
are described above in this disclosure with reference to FIGURES 1 through
12).
[00139] FIGURES 13A and 17 further illustrate: Upper and lower boots 1210U,
1210L; upper
and lower boot retaining rings 1211U, 1211L; and upper and lower split rings
1212U, 1212L.
Boots 1210U/L, boot retaining rings 1211U/L and split rings 1212U/L
advantageously seal the
connection between shaft 1101 and upper and lower housings 1205U, 1205L at
either end of
- 41 -
Date Recue/Date Received 2022-02-25
shaft 1101. Boots 1210U/L are preferably made of a rubber or elastomer
material in order to
provide seals while at the same time permitting independent articulation
between shaft 1101 and
upper housing 1205U at one end of shaft 1101, and between shaft 1101 and lower
housing
1205L at the other end of shaft 1101.
[00140] From this point forward in the discussion of FIGURES 13A through 20H,
the Figures
and associated disclosure will describe features, aspects and alternative
embodiments with
reference to assemblies at the "low side" as drawn on FIGURES 13A and 17. That
is, the
Figures and associated disclosure will describe features, aspects and
alternative embodiments in
and around and associated with lower housing assembly 1200L as depicted on
FIGURES 13A
and 17. Persons of ordinary skill in this art will require very little
experimentation to reverse the
orientation of embodiments illustrated with reference to the "low side" on
FIGURES 13A and 17
in order to understand corresponding assemblies and features on the "high
side".
[00141] FIGURE 13B is a perspective view of lower housing 1205L on FIGURE 13A
in
isolation. FIGURE 13C is a section as shown on FIGURE 13B. FIGURE 13B shows
that lower
housing 1205L is generally hollow, providing housing cavity 1206 formed
therein. FIGURE
13C shows housing cavity receptacles 1207 provided in lower housing 1205L
generally at a
periphery of housing cavity 1206. With momentary reference to FIGURES 13A and
17, it will
be appreciated that lower housing 1205L provides one (1) housing cavity
receptacle 1207 each
for receiving a corresponding shaft pin 1106 on shaft head 1102. Thus, five
(5) housing cavity
receptacles 1207 are illustrated on FIGURE 13C, one each for receiving a
corresponding one of
the five (5) shaft pins 1106 shown on FIGURE 17.
-42 -
Date Recue/Date Received 2022-02-25
[00142] FIGURE 13C further illustrates that each housing cavity receptacle
1207 provides a
housing bearing surface 1203 and a housing backlash surface 1202. FIGURE 13B
illustrates
housing bearing surfaces 1203 and housing backlash surfaces 1202 in
perspective view.
[00143] FIGURES 13B and 13C further illustrate optional hard facing 1209
inside lower
housing 1205L. In embodiments where provided, hard facing 1209 assists
reducing thrust wear
between shaft head 1102 and lower housing 1205L during articulated /
misaligned rotation of
shaft head 1102 as received in lower housing 1205L. It will be understood that
hard facing 1209
may optionally also be provided in upper housing 1205U. In other non-
illustrated embodiments,
hard facing may be provided on the tip of shaft head 1102, or a thrust bearing
may be provided
instead of hard facing 1209.
[00144] FIGURE 14A is a section as shown on FIGURE 13A. FIGURE 14B is a
section as
shown on FIGURE 14A. FIGURES 14A and 14B show shaft pins 1106 engaged with
TTEs
1300 in housing cavity receptacles 1207. Curved shaft pin bearing surfaces
1109 on shaft pins
1106 slidably engage with curved TTE pin bearing surfaces 1301. TTE housing
bearing surfaces
1302 further slidably engage with housing bearing surfaces 1203. Following the
convention of
clockwise shaft rotation R looking downhole per FIGURE 13A, FIGURE 14A
illustrates applied
torque transfer in a clockwise direction in the following sequence: (A) from
shaft pins 1106 on
shaft head 1102 into TTEs 1300; and then (B) through TTEs 1300 and into lower
housing 1205L
via housing bearing surfaces 1203. FIGURES 14A and 14B further illustrate that
during such
applied clockwise torque transfer, TTE housing bearing surface 1302 bears upon
housing bearing
surface 1203. FIGURE 14B also shows that during such applied clockwise torque
transfer,
curved shaft pin bearing surfaces 1109 provided on shaft pins 1106 bear upon
curved TTE pin
bearing surfaces 1301.
-43 -
Date Recue/Date Received 2022-02-25
[00145] With reference now to FIGURE 17, it will be understood that a reverse
transfer
sequence enables "applied clockwise torque transfer looking downhole" at upper
housing
assembly 1200U, in which torque is transferred in the following sequence: (A)
from upper
housing 1205U into TTEs 1300; and then (B) into shaft pins 1106 on shaft head
1102. This
reverse sequence is like imagining torque transfer on FIGURE 14A in the
opposite direction
(counterclockwise) to rotation direction R as illustrated on FIGURE 14A.
[00146] With further reference now to FIGURES 14A and 14B, it will be
appreciated that in
currently preferred embodiments, the illustrated geometries are designed so
that the maximum
shaft pin diameters 1110 on shaft pins 1106 are on a locus 1409 whose diameter
coincides with
the external diameter of lower housing assembly 1200L at lower housing threads
1201L (such
external diameter also illustrated on FIGURE14A as dotted line 1409). In this
way, in such
currently preferred embodiments, torque is directly transferred through the
full cross-section of
lower housing assembly 1200L at lower housing threads 1201L, substantially
unifying the torque
stress gradients across lower housing assembly 1200L at that threaded
connection. It will
nonetheless be appreciated, however, that the scope of this disclosure is not
limited to
deployments in which locus 1409 of maximum shaft pin diameters 1110 coincides
with the
external diameter of lower housing assembly 1200L at lower housing threads
1201L.
[00147] Additionally, as further shown on FIGURES 14A and 14B, shaft pins 1106
are free to
slidably rotate about TTEs 1300 during misaligned (articulated) rotation of
shaft 1101.
Likewise, TTEs 1300 are free to slidably displace within housing cavity
receptacles 1207 during
misaligned (articulated) rotation of shaft 1101. Shaft pins 1106 are disposed
to rotate about
TTEs 1300 at the interface between curved shaft pin surfaces 1109 and curved
TTE pin bearing
surfaces 1301. TTEs 1300 are disposed to slidably displace within housing
cavity receptacles
-44 -
Date Recue/Date Received 2022-02-25
1207 at the interface between TTE housing bearing surfaces 1302 and housing
bearing surfaces
1203. FIGURE 14B illustrates that rotation of shaft pins 1106 about TTEs 1300
is about shaft
pin centerlines 1107, and that the interface between curved shaft pin surfaces
1109 and TTE pin
bearing surfaces 1301 is at shaft pin radius 1111 from shaft pin centerline
1107. FIGURE 14B
further shows that shaft pin radius 1111 defines the maximum shaft pin
diameter 1110 for shaft
pins 1106. FIGURES 13A and 14B illustrate that sliding displacement of TTEs
1300 within
housing cavity receptacles 1207 is in a direction generally parallel to the
shaft's untilted
(undeflected) axial centerline 1103, such that the TTEs 1300 float at least
generally parallel to an
untilted axial shaft centerline 1103 when the TTE housing bearing surfaces
1302 slidably
displace against corresponding housing bearing surfaces 1203. [Undeflected (or
untilted) shaft
centerline 1103 is also shown on FIGURE 19B].
[00148] FIGURE 18 is a further partial cutaway view of lower housing assembly
1200L as also
illustrated on FIGURE 13A. FIGURE 19A is a section as shown on FIGURE 18.
FIGURES
19B and 19C are "faux section" views as shown FIGURE 19A, depicting shaft
assembly 1100
substantially assembled at lower housing assembly 1200L per FIGURES 13A, 14A
and 14B, in
which FIGURES 19B and 19C combine to schematically depict articulation during
misaligned
rotation. By "faux section" views, it will be understood from FIGURE 14A, for
example, that
since the illustrated embodiments depict five (5) shaft pins 1106 and
associated TTEs 1300
distributed evenly around the periphery of shaft head 1102, a true straight
line section through
the assembly of shaft assembly 1100 at lower housing assembly 1200L does not
allow shaft pins
1106 on opposite sides of shaft head 1102 to be seen on one view. Thus,
FIGURES 19B and
19C depict more of a "pie-shaped" or "offset" section through the assembly of
shaft assembly
-45 -
Date Recue/Date Received 2022-02-25
1100 at lower housing assembly 1200L, so that shaft pins 1106 on opposite
sides of shaft head
1102 can be seen on each of FIGURES 19B and 19C.
[00149] FIGURE 18 illustrates parts and features also described above with
reference to
FIGURES 13A, 14A and 14B, including shaft 1101, shaft pins 1106, lower housing
1205L and
TTEs 1300. FIGURE 18 also illustrates shaft pin centerline 1107 and shaft pin
radius 1111 as
previously described above with reference to FIGURE 14B.
[00150] FIGURES 18, 19B and 19C should now be viewed together. FIGURE 18
illustrates
shaft deflection angle a disposed about shaft pin centerline 1107. Although
shown disposed
about shaft pin centerline 1107 on FIGURE 18, FIGURE 19C illustrates that
shaft deflection
angle a actually represents an angle of shaft deflection (or tilt, or
articulation) either side of
undeflected shaft centerline 1103 during misaligned rotation of shaft 1101.
FIGURE 19C shows
that at the illustrated moment, deflected shaft centerline 1104 is angularly
displaced (or "tilted")
from undeflected shaft centerline 1103 by a/2, where such angular displacement
(tilt) is in a first
angular direction of shaft misalignment. It will be further understood that
although not
specifically illustrated, shaft 1101 will also be angularly deflected (tilted)
by a/2 in a second
angular direction of shaft misalignment during one full revolution of
misaligned rotation by shaft
1101, where the first and second angular directions oppose one another either
side of undeflected
shaft centerline 1103. Shaft deflection angle a thus represents the combined
angular deflection
(tilt) of shaft 1101 in both the first and second angular directions either
side of undeflected shaft
centerline 1103 during one full revolution of misaligned shaft rotation.
[00151] Now comparing FIGURE 19B with FIGURE 19C, it will be seen on FIGURE
19B that
shaft 1101 is in an undeflected condition such that undeflected shaft
centerline 1103 is
continuous through shaft 1101 and lower housing 1205L. Shaft pin 1106 on
FIGURE 19B is in a
-46 -
Date Recue/Date Received 2022-02-25
"neutral" position with respect to TTE 1103. In contrast, shaft 1101 on FIGURE
19C is shown
in a deflected condition as described immediately above, such that deflected
shaft centerline
1104 on FIGURE 19C is angularly displaced (tilted) from undeflected shaft
centerline 1103 by
a/2. Shaft pin 1106 on FIGURE 19C is also shown in a deflected condition with
respect to TTE
1300. Shaft pin 1106 has rotated an angle of a/2 about shaft pin centerline
1107 with respect to
TTE 1300. Likewise, curved shaft pin bearing surface 1109 on shaft pin 1106
has slidably
rotated an angle of a/2 about shaft pin centerline 1107 with respect to curved
TTE pin bearing
surface 1301 on TTE 1300. FIGURE 18 further illustrates the potential for such
rotation of shaft
pins 1106 about shaft pin centerline 1107 with respect to TTE 1300. FIGURE 18
shows such
potential for rotation by a/2 either side of an undeflected condition (as
shown on FIGURE 19B)
for a total overall potential shaft deflection angle a.
[00152] FIGURES 19B and 19C further illustrate that TTEs 1300 remain in a
generally
stationary angular position while shaft pins 1106 rotate about shaft pin
centerlines 1107 during
misaligned rotation (tilt) of shaft 1101. However, with additional reference
to FIGURE 14B, it
will be appreciated that TTEs 1300 are disposed (and are free) to slidably
displace within
housing cavity receptacles 1207 during misaligned rotation (tilt) of shaft
1101. As shaft pins
1106 rotate with respect to TTEs 1300 during tilt, TTEs 1300 are disposed (and
are free) to
displace within housing cavity receptacles 1207 via sliding contact between
TTE housing
bearing surfaces 1302 and housing bearing surfaces 1203. As described above,
FIGURES 13A
and 14B illustrate that such sliding displacement of TTEs 1300 within housing
cavity receptacles
1207 is in a direction generally parallel to the shaft's untilted
(undeflected) axial centerline 1103,
such that the TTEs 1300 float at least generally parallel to an untilted axial
shaft centerline 1103
-47 -
Date Recue/Date Received 2022-02-25
when the TTE housing bearing surfaces 1302 slidably displace against
corresponding housing
bearing surfaces 1203.
[00153] The foregoing description of torque transfer via unlaminated bearings
(TTEs) has been
made with reference to illustrated embodiments in which two housing assemblies
1200U and
1200L are provided, one at each end of shaft 1101. The scope of this
disclosure is not limited,
however, to two housing assemblies on shaft 1101. Other embodiments (not
illustrated) may
provide only one housing assembly on shaft 1101, on a selected end thereof. In
such other
embodiments, the scope of this disclosure is further not limited as to the
selected end of shaft
1101 (high side or low side on FIGURE 13A) on which the single housing
assembly is to be
provided.
[00154] The foregoing description of torque transfer via both laminated
bearings and
unlaminated bearings (TTEs) has been made with "pure" assemblies in which all
bearings in one
articulating assembly are either laminated or unlaminated. The scope of this
disclosure is not
limited, however, to such "pure" embodiments. Other embodiments (not
illustrated) may include
"hybrid" articulating assemblies, inside which laminated bearings arrangements
(such as
described herein with reference to FIGURES 1 through 12) are mixed with
unlaminated bearings
arrangements (such as described herein with reference to FIGURES 13A through
20H).
[00155] Referring now to FIGURES 13A and 17, it will be understood that torque
backlash will
be created in upper and lower housing assemblies 1200U, 1200L whenever applied
torque
through shaft 1101 is reduced, stopped or even reversed. Torque backlash may
be momentary or
sustained, responsive to corresponding changes in transmitted torque over time
through shaft
1101. Under the above-described "clockwise looking downhole" convention of
shaft rotation
direction R on FIGURES 13A and 17, torque backlash will be in a
counterclockwise direction in
-48 -
Date Recue/Date Received 2022-02-25
response to applied clockwise torque looking downhole. Torque backlash thus
manifests itself
on FIGURE 14A, for example, in the opposite direction (counterclockwise) to
the clockwise
shaft rotation direction R looking downhole shown on FIGURE 14A.
[00156] FIGURE 14A illustrates that during torque backlash events in lower
housing assembly
1200L, applied torque is no longer transferred through TTEs 1300. Instead,
counterclockwise
torque backlash causes shaft backlash surface 1105 to bear upon housing
backlash surface 1202.
Although not specifically illustrated, it will be understood that the
corresponding effect occurs in
upper housing assembly 1200U.
[00157] FIGURES 20A through 20H illustrate currently preferred embodiments of
alternative
backlash energizer assemblies, which, when provided, seek to remediate
negative effects of
torque backlash. FIGURE 20A is a section similar to FIGURE 14A, except
depicting an
alternative embodiment including backlash energizer assembly 1400. FIGURE 20B
is an
exploded view of backlash energizer assembly 1400 from FIGURE 20A in
isolation. FIGURES
20C and 20D, FIGURES 20E and 20F, and FIGURES 20G and 20H are each matched
pairs of
cutaway section views and corresponding exploded isolation views of
alternative backlash
energizer embodiments 1404, 1404A and 1420.
[00158] Referring first to FIGURES 20A and 20B, backlash energizer assemblies
1400 each
include set screw 1401, puck 1402, and Belleville washer 1403. Pucks 1402 are
preferably of
unitary hard material construction, such as metal or ceramic. Each backlash
energizer assembly
1400 is shown on FIGURE 20A interposed between a shaft backlash surface 1105
and a
corresponding housing backlash surface 1202. Each Belleville washer 1403 is
configured to
contact and provide compression bias against shaft backlash surface 1105 such
that torque
backlash will act against Belleville washer 1403's bias during backlash
events. Each Belleville
-49 -
Date Recue/Date Received 2022-02-25
washer 1403 is further positioned to react against puck 1402 as received into
a corresponding
recess in housing backlash surface 1202. Set screws 1401 may be inserted from
the outside of
lower housing 1205L through openings 1208 provided for such purpose. Set
screws 1401
engage threads provided in openings 1208 to set a user-desired compression
bias for Belleville
washers 1403 against shaft backlash surfaces 1105.
[00159] It will thus be appreciated from FIGURES 20A and 20B that backlash
energizer
assemblies 1400 dampen and absorb torque backlash during backlash events.
Belleville washers
1403 (and their associated compression bias) receive torque backlash, and may
further
temporarily store some of the torque backlash energy during backlash events.
Several technical
advantages are thus provided. Wear between shaft backlash surface 1105 and
housing backlash
surface 1202 is reduced, Concussive energy loss between shaft backlash surface
1105 and
housing backlash surface 1202 is also reduced by removal of a gap between the
two. Further,
torque energy during backlash events is not completely lost. Referring to
FIGURE 20A, any
torque backlash energy stored in Belleville washers 1403 during a backlash
event will be
released when clockwise torque is reestablished (per shaft rotation direction
R shown on
FIGURE 20A). Further, compression bias of Belleville washers 1403 tends to
keep shaft pins
1106, TTEs 1300 and housing bearing surfaces 1203 fully engaged by continuous
contact during
both normal torque transfer periods and torque backlash events. This in turn:
(1) reduces wear
on contact surfaces on shaft pins 1106, TTEs 1300 and housing bearing surfaces
1203; (2)
reduces concussive energy loss during a transition back to normal torque after
a torque backlash
event; and (3) reduces the chance of TTEs 1300 becoming dislocated between
shaft pins 1106
and housing bearing surfaces 1203 during torque backlash events.
- 50 -
Date Recue/Date Received 2022-02-25
[00160] FIGURES 20C and 20D illustrate an alternative embodiment to the
backlash energizer
assembly 1400 of FIGURES 20A and 20B. On FIGURES 20C and 20D, torque backlash
remediation is provided by a single puck 1404. Similar to puck 1402 in
backlash energizer
assembly 1400, puck 1404 is preferably of unitary hard material construction,
such as metal or
ceramic. Puck 1404 on FIGURES 20C and 20D provides advantages of simplicity of
construction and assembly over backlash energizer 1400 on FIGURES 20A and 20B,
at the
expense of advantages that may be provided by the compression bias of
Belleville washer 1403
in backlash energizer 1400, described above.
[00161] FIGURES 20E and 20F illustrate an alternative embodiment to the
backlash energizer
embodiment illustrated on FIGURES 20C and 20D. On FIGURES 20E and 20F, a
laminated
puck 1404A substituted for the plain single puck 1404 of FIGURES 20C and 20D.
Laminated
puck 1404A provides a resilient laminate construct for opposing contact with
shaft backlash
surface 1105, in which the laminate preferably includes alternating elastomer
layers 1405 and
metal layers 1406. The laminate, however, may be of any suitable materials.
The scope of this
disclosure is not limited in this regard. The scope of this disclosure is
further not limited to the
design of laminate, including as to number of layers and their thicknesses.
Puck 1404A on
FIGURES 20E and 20F provides similar advantages of simplicity of construction
and assembly
as puck 1404 on FIGURES 20C and 20D, and the laminar construction of puck
1404A may also
provide some (or all) of the advantages that may be provided by the
compression bias of
Belleville washer 1403 in backlash energizer 1400, described above.
[00162] FIGURES 20G and 20H illustrate backlash energizer assembly 1420 as a
yet further
alternative embodiment to backlash energizers previously described with
reference to FIGURES
20A and 20B, 20C and 20D, and 20E and 20F. Backlash energizer assembly 1420
includes set
-51 -
Date Recue/Date Received 2022-02-25
screw 1421, plate 1422 and ball 1423. Backlash energizer assembly 1420 on
FIGURES 20G and
20H is similar in overall design to backlash energizer assembly 1400 on
FIGURES 20A and
20B, except that plate 1422 in assembly 1420 substitutes for puck 1402 in
assembly 1400, and
ball 1423 in assembly 1420 substitutes for Belleville washer 1423 in assembly
1400. Also,
comparing FIGURES 20G and 20A, the recess provided in lower housing 1205L for
plate 1422
and ball 1423 on FIGURE 20G may have to be adapted dimensionally to suit plate
1422 and ball
1423 as compared to the corresponding recess for puck 1402 and Belleville
washer 1403 on
FIGURE 20A. Preferably, the recess provided on FIGURE 20G leaves sufficient
clearance from
ball 1423 to allow ball 1423 to rotate within such recess. Backlash energizer
assembly 1420 on
FIGURES 20G and 20H thus further facilitates keeping shaft pins 1106, TTEs
1300 and housing
bearing surfaces 1203 fully contact-engaged during both normal torque periods
and torque
backlash events even when (especially when) there is relative articulating
movement between
shaft backlash surface 1105 and housing backlash surface 1202. It will be
appreciated that in
previously described embodiments (FIGURES 20A and 20B, 20C and 20D, and 20E
and 20F),
keeping shaft pins 1106, TTEs 1300 and housing bearing surfaces 1203 fully
contact-engaged
during relative articulating movement between shaft backlash surface 1105 and
housing backlash
surface 1202 requires sliding contact between shaft backlash surface 1105 and
Belleville washer
1403, and pucks 1404 and 1404A respectively. Such sliding contact may lead to
wear and/or
loss of contact between shaft backlash surface 1105 and Belleville washer
1403, and pucks 1404
and 1404A respectively. Rolling contact between shaft backlash surface 1105
and ball 1423 on
FIGURES 20G and 20H remediates any such concerns brought on by corresponding
sliding
contact in other backlash energizer embodiments.
- 52 -
Date Recue/Date Received 2022-02-25
[00163] It will be understood that the scope of this disclosure is not limited
to the backlash
energizer designs described above. The scope of this disclosure is not limited
to any specific
backlash energizer embodiment or configuration thereof. Some embodiments may
provide no
backlash energizer at all, or a hybrid including backlash energizers in some
locations and not
others. Some embodiments may further provide hybrids in which different
backlash energizer
designs are mixed on one housing assembly, or over two housing assemblies
(upper and lower).
Such embodiments providing mixed configurations may also include hybrid
embodiments in
which no backlash energizer is provided at selected locations.
[00164] FIGURES 15A through 15G illustrate various alternative Torque Transfer
Element
("TTE") embodiments. Earlier disclosure identified TTEs 1300 included in the
illustrated
embodiments of upper and lower housing assemblies 1200U, 1200L on FIGURES 13A,
14A,
14B and 17. FIGURE 15A illustrates TTE 1300A, which for reference is the same
TTE
embodiment as TTE 1300 depicted on FIGURES 13A and 17. FIGURES 15B through 15G
illustrate TTEs 1300B through 1300G respectively (in which TTE 1300B through
1300G are
alternative embodiments to TTE assembly 1300A on FIGURE 15A). FIGURE 16 is an
enlargement as shown on FIGURE 15B.
[00165] TTE 1300A on FIGURE 15A includes curved TTE pin bearing surface 1301A
and TTE
housing bearing surface 1302A, which correspond to TTE pin bearing surface
1301 and TTE
housing bearing surface 1302 on FIGURES 13A, 14A, 14B and 17, for example.
[00166] FIGURE 15B and FIGURE 16 are similar to FIGURES 3 and 4. FIGURES 3 and
4 are
described in detail above in this disclosure. TTE 1300B on FIGURE 15B includes
curved TTE
pin bearing surface 1301B and TTE housing bearing surface 1302B. Curved TTE
pin bearing
surface 1301B and TTE housing bearing surface 1302B on FIGURE 15B each include
a laminate
- 53 -
Date Recue/Date Received 2022-02-25
for opposing contact with curved shaft pin bearing surface 1109 and housing
bearing surface
1203 (refer FIGURE 14B, for example). The laminate preferably includes
alternating TTE
elastomer and metal layers, such as TTE elastomer layers 1314 and TTE metal
layers 1312 on
curved TTE pin bearing surface 1301B depicted on FIGURE 16. The laminate,
however, may be
of any suitable materials. The scope of this disclosure is not limited in this
regard. The scope of
this disclosure is further not limited to the design of laminate, including as
to number of layers
and their thicknesses. TTE 1300B on FIGURE 15B, with its laminated bearing
surfaces, enables
resilient contact with curved shaft pin bearing surface 1109 and housing
bearing surface 1203
with some compression bias. With further reference to FIGURE 14B, such
compression bias
assists with keeping shaft pins 1106, TTEs 1300B and housing bearing surfaces
1203 fully
engaged by continuous contact during both normal torque transfer periods and
torque backlash
events. In particular, and referring momentarily to FIGURE 14A, it will be
understood that
compression bias from TTE 1300B may retain shaft pins 1106, TTEs 1300B and
housing bearing
surfaces 1203 together during misaligned rotation.
[00167] Referring now to FIGURES 15C through 15G together, TTEs 1300C through
1300G
each include curved TTE pin bearing surfaces 1301C through 1301G and TTE
housing bearing
surfaces 1302C through 1302G respectively. TTE housing bearing surfaces 1302C,
1302F and
1302G each differ from curved TTE housing bearing surface 1302A on FIGURE 15A
in that
they have curvature, whereas TTE housing bearing surface 1302A on FIGURE 15A
is
substantially planar. TTE housing bearing surface 1302C on FIGURE 15C is
curved in a
longitudinal transmission assembly direction (i.e. parallel to undeflected
shaft centerline 1103
shown on FIGURES 19B and 19C). TTE housing bearing surface 1302F on FIGURE 15F
is
curved in a transverse direction 1325F (i.e. orthogonal to undeflected shaft
centerline 1103
- 54 -
Date Recue/Date Received 2022-02-25
shown on FIGURES 19B and 19C). TTE housing bearing surface 1302G on FIGURE 51G
is
curved in both longitudinal and transverse directions (1325G). With momentary
reference to
FIGURES 14A and 14B, curvature on TTE housing bearing surfaces 1302C, 1302F
and 1302G
further assists with continuous contact between housing bearing surfaces 1203
and TTE housing
bearing surfaces 1302C, 1302F and 1302G during misaligned rotation.
[00168] Referring now to FIGURE 15D, TTE 1300D includes curved TTE pin bearing
surface
1301D and TTE housing bearing surface 1302D. TTE 1300D on FIGURE 15D is a
further
alternative embodiment to TTE 1300A on FIGURE 15A. TTE housing bearing surface
1302D
on FIGURE 15D differs from TTE housing bearing surface 1302A on FIGURE 15A in
that TTE
housing bearing surface 1302D includes angled faces at the periphery, whereas
TTE housing
bearing surface 1302A on FIGURE 15A is substantially planar. Embodiments
according to
FIGURE 15D are useful to provide clearance at the edges of TTE housing bearing
surface
1302D in limited space deployments where the corners of TTE 1300D might
interfere with
corners in housing cavity receptacle 1207 (refer to FIGURE 14B, for example).
[00169] Referring now to FIGURE 15E, TTE 1300E includes curved TTE pin bearing
surface
1301E and TTE housing bearing surface 1302E. TTE 1300E on FIGURE 15E is a
further
alternative embodiment to TTE 1300A on FIGURE 15A. Curved TTE pin bearing
surface
1301E on FIGURE 15E differs from curved TTE pin bearing surface 1301A on
FIGURE 15A in
that curved TTE pin bearing surface 1301E provides hard facing 1330E. (It will
be understood
that hard facing 1330E is actually integral with curved TTE pin bearing
surface 1301E although
illustrated as a separate item for clarity). It will be further appreciated
that internal hard facing
1300E on curved TTE pin bearing surface 1301E, per FIGURE 15E, reduces contact
wear on
curved TTE pin bearing surface 1301E during misaligned shaft rotation.
- 55 -
Date Recue/Date Received 2022-02-25
[00170] It will be understood that the scope of this disclosure is not limited
to the various TTE
designs described above. The scope of this disclosure is not limited to any
specific TTE
embodiment or configuration thereof. Some embodiments may provide hybrids in
which
different TTE designs are mixed on one housing assembly, or over two housing
assemblies
(upper and lower). Further, TTE designs as described above may be combined
into single TTE
embodiments (such as, for example, combining the hard facing embodiment of
FIGURE 15E
with a curved TTE housing bearing surface embodiment selected from FIGURES
15C, 15F or
15G into one hybrid TTE embodiment).
[00171] Although the inventive material in this disclosure has been described
in detail along
with some of its technical advantages, it will be understood that various
changes, substitutions
and alternations may be made to the detailed embodiments without departing
from the broader
spirit and scope of such inventive material as set forth in the following
claims.
- 56 -
Date Recue/Date Received 2022-02-25
