Note: Descriptions are shown in the official language in which they were submitted.
t CA 02330987 2001-01-11-
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PROTECTED LUBRICANT RESERVOIR
WITH PRESSURE CONTROL
FOR SEALED BEARING EARTH BORING DRILL BIT
BACKGROUND OF THE INVENTION
The invention relates generally to sealed bearing earth boring drill bits,
such as rotary
cone rock bits, that utilize a fluid circulation medium. More particularly,
the invention relates to
such drill bits that include a protected lubricant reservoir.
More specifically, drill bits are generally known, and fall into at least two
categories.
Drill bits used for drilling petroleum wells and drill bits used in the mining
industry are both well
known in the art. While these two types of bits superficially resemble each
other, the
parameters that affect the operation of each are completely different.
Petroleum drill bits
typically use a viscous, heavy drilling fluid (mud) to flush the cuttings from
the vicinity of the bit
and carry them out of the hole, whereas mining bits typically use compressed
air to achieve the
same purpose. Petroleum bits typically drill deep holes, on the order of
thousands of feet, and an
average bit typically drills several hundreds or thousands of feet before
being removed from the
hole. In many instances, a petroleum bit is not withdrawn from the hole until
it has exhausted its
useful life. In contrast, mining bits are each used to drill several
relatively shallow holes,
typically only 30-50 feet deep, and must be withdrawn from each shallow hole
before being
shifted to the next hole. Thus, the effect of withdrawal and backreaming wear
on the body of a
mining bit are much more important considerations than they are for petroleum
bits. In addition,
because petroleum bits drill near the surface they are more frequently
subjected to cave-ins, and
must ream their way backwards out of the hole through the caved-in material.
For these reasons,
the factors that affect the design of mining bits are very different from
those that affect the
design of petroleum bits.
For instance, the viscosity and density of the drilling mud makes it possible
to flush the
cuttings from the hole even at relatively low fluid velocities. The air used
to flush cuttings from
mining holes, in contrast, is much less viscous and dense and therefore must
maintain a rapid
velocity in order to successfully remove the rock chips. This means that the
cross-sectional area
through which the air flows at each point along the annulus from the bit to
the surface must be
carefully maintained within a given range. Similarly, the rapid flow of air
across and around a
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CA 02330987 2001-O1-11
rock bit greatly increases the erosive effect of the cuttings, particularly on
the leading portions of
the bit.
Furthermore, rock bits are now being developed with sealed lubrication systems
that
allow easier rotation of the bit parts. These sealed lubrication systems
typically comprise a
lubricant reservoir in fluid communication with the bearings. In many cases,
the reservoir is
created by drilling a cavity into the bit leg. Access to the reservoir is
through the installation
opening of this cavity, which can then be sealed with a conventional plug or
vented plug. These
sealed lubrication systems are particularly vulnerable to erosion of the bit
body, as any breach of
the sealed system can result in the ingress of cuttings and/or particles into
the bearings, causing
bit failure. Heretofore, the reservoir opening has been located on the main
outer face of each leg,
with the result that the reservoir plugs and the walls of the reservoir itself
are vulnerable to wear
on the leg.
Hence it is desirable to provide a mining bit that provides increased
protection for the
reservoir and its installation opening and plug. It is further desired to
provide a bit that is
capable of withstanding wear on its shoulders and legs during backreaming or
as the bit is being
withdrawn from a hole.
In addition, it has been found that the pressure in the lubricant reservoir,
and more
particularly the pressure drop across the dynamic seals, can affect the
performance of the
dynamic seals and of the lubricant system in general. Hence, it has become
desirable to control
the fluid pressure in the lubricant reservoir. It is further desirable to do
so without compromising
the integrity of the sealed bearing system or rendering it vulnerable to
excessive wear.
SUMMARY OF THE INVENTION
The present invention relates to a rock bit having a sealed lubricant system
with a
lubricant reservoir in at least one, and preferably at least each of the legs
of the bit. The lubricant
reservoir preferably has an installation opening that is protected from damage
during back
reaming operations. According to various embodiments, an installation opening
for each
reservoir can be located on the leading surface, center panel surface,
trailing surface, and/or on
the shoulder of the leg in which the reservoir is formed. The lubricant
reservoir further includes,
a pressure equilibrating device, such as a membrane or diaphragm, in fluid
communication with
either the bit plenum or the annulus surrounding the bit, so that the pressure
inside the reservoir
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can be controlled to desired levels. The pressure equilibrating device is
preferably located in the
passage formed by the installation opening.
BRIEF DESCRIPTION OF THE DRAWINGS
For a detailed description of the preferred embodiments of the invention,
reference will now
be made to the accompanying drawings wherein:
Figure 1 is an isometric view of a rotary cone drill bit of the present
invention;
Figure 2 is a side view of one leg of the drill bit of Figure 1;
Figure 3 is a cross-sectional view of a rotary cone drill bit of the prior art
in a bore hole;
Figure 4 is a front elevation view of one leg of a rotary cone drill bit
having a first
embodiment of a protected lubricant reservoir;
Figure 5 is a cross-sectional view at plane 5-S in Figure 4;
Figure SA is an alternative embodiment of the leg shown in Figures 4 and 5;
Figure 6 is a front elevation view of one leg of a rotary cone drill bit
having a second
embodiment of a protected lubricant reservoir;
Figure 7 is a front elevation view of one leg of a rotary cone drill bit
having a third
embodiment of a protected lubricant reservoir;
Figure 8 is a front elevation view of one leg of a rotary cone drill bit
having a fourth
embodiment of a protected lubricant reservoir;
Figure 9 is a cross-sectional view at plane 9-9 in Figure 8;
Figure 10 is a front elevation view of one leg of a rotary cone drill bit
having a fifth
embodiment of a protected lubricant reservoir;
Figure 11 is a cross-sectional view at plane 11-11 in Figure 10;
Figure 12 is a cross-sectional view of one leg of a rotary cone drill bit
having a sixth
embodiment of a protected lubricant reservoir;
Figure 13 is an exploded view of the protected lubricant reservoir of Figure
12;
Figure 14 is a cross-sectional view of one leg of a rotary cone drill bit
having a seventh
embodiment of a protected lubricant reservoir;
Figure 15 is a cross-sectional view of one leg of a rotary cone drill bit
having an eighth
embodiment of a protected lubricant reservoir;
Figure 16 is a cross-sectional view of a rotary cone drill bit having a ninth
embodiment of a
protected lubricant reservoir;
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Figure 16a is a cross-sectional view at plane 16a -16a in Figure 16;
Figure 17 is a cross-sectional view of a rotary cone drill bit having a tenth
embodiment of a
protected lubricant reservoir;
Figure 18 is a cross-sectional view of one leg of a rotary cone drill bit
having an eleventh
S embodiment of a protected lubricant reservoir;
Figure 19 is a front elevation view of one leg of a rotary cone drill bit
having a twelfth
embodiment of a protected lubricant reservoir;
Figure 20 is a front elevation view of one leg of a rotary cone drill bit
having three protected
lubricant reservoirs in accordance with the present invention; and
Figure 21 is a cross-sectional view of one leg of a rotary cone drill bit
having yet another
embodiment of a protected lubricant reservoir.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Presently preferred embodiments of the invention are shown in the above-
identified
figures and described in detail below. In illustrating and describing the
preferred embodiments,
1 S like or identical reference numerals are used to identify common or
similar elements. The
figures are not necessarily to scale and certain features and certain views of
the figures may be
shown exaggerated in scale or in schematic form in the interest of clarity and
conciseness.
Referring initially to Figures 1-2, a sealed-bearing earth boring bit 10 is
shown. The bit
10 illustrated is a rotary cone rock bit used for drilling blast holes in
mining operations that
utilizes fluid circulation to cool and clean the bit 10 and to transport
earthen cuttings and debris
up the bore hole to the surface (not shown). It should be understood that the
present invention is
not limited to rotary cone rock bits 10 for mining operations, but may be used
in other types of
sealed bearing earth boring drill bits for any other desirable earthen
drilling applications, such as
petroleum well, pipeline, sewage and electrical conduit drilling.
The bit includes a bit body 12, a pin end 14 and a cutting end 16. The pin end
14
includes a connector 13, such as a threaded pin connection 15, for connecting
the bit 10 to a
carrier, such as a drill string (not shown). The bit body 12 includes legs 20
extending generally
between the pin end 14 and the cutting end 16 of the bit 10. At the cutting
end 16, each leg 20
carries a cutter cone 18 having a multitude of protruding cutting elements 19
for engaging the
earthen formation and boring the bore hole 17 as the bit 10 is rotated in a
clockwise direction
when viewed from the pin end 14. Typically, rotary cone drill bits 10 have
three legs 20 and
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cones 18, although the present invention may be used in bits 10 with any
number of leg 20/cone
18 combinations. While portions of the description of the preferred
embodiments of the present
invention are made herein with reference to a single leg 20, such discussions
apply equally to
each leg 20 of a bit 10 in accordance with the present invention.
Still referring to Figures 1 and 2, a plenum 80, having a plenum surface 82
extends
through the bit 10 to allow the supply of circulation fluid (not shown) to one
or more nozzles 84
formed in legs 20, as is known in the art. The circulation fluid, such as gas
or drilling mud, is
provided into the plenum 80 from a fluid supply source (not shown) and through
a supply
conduit, such as a drill string (not shown), attached to the pin end 14 of the
bit 10. Each nozzle
84 extends from the plenum 80 to a port 86, which opens to the exterior 70 of
the bit 10, as is
known in the art. A nozzle boss 90 is disposed on the leg 20 over the nozzle
84. The nozzles 84
operate to direct pressurized fluid against the bottom 71 of the bore hole 17
(Figure 3) to lift
earthen cuttings and other debris up through the bore hole 17. The nozzles 84
also direct the
circulation fluid over the cones 18 and cutting elements 19 to free debris
accumulating
thereabout.
Now referring to Figure S, the bit 10 includes a bearing system 50 for
permitting rotation
of the cone 18 about a journal 23 extending from the leg 20. The bearing
system 50 may be a
roller bearing system SOa, as is, or becomes, known in the art, such as the
roller bearing system
disclosed in U.S. Patent Number 5,793,719 to Crockett et al. The roller
bearing system SOa
includes various conventional roller bearing components, such as, for example,
cone bearing
surfaces 52, journal bearing surfaces 54, roller bearings 56 and locking balls
58, disposed in the
interior 59 of the cone 18. A roller bearing system SOa compatible for use
with the bit 10 of the
present invention is also shown with respect to the prior art bit 10a of
Figure 3. Alternately, the
bearing system 50 may be a friction bearing system SOb (Figure 9) including
conventional
friction bearing system components as are or become known in the art. In
either type of bearing
system SOa, SOb, a locking ball loading hole 57 may be formed into the leg 20
for loading the
locking balls 58 into the cone interior 59. A ball retaining plug 55 (Figure
9) is typically disposed
in the hole 57 for retaining the locking balls 58.
Referring to Figure 9, lubricant, such as grease (not shown), is provided to
the roller
bearing system 50 via a lubricant reservoir system 60. A reservoir system 60
compatible for use
CA 02330987 2001-O1-11
with the bit 10 of the present invention is also shown with respect to the
prior art bit 10a of
Figure 3. The reservoir system 60 includes one or more reservoirs 62 disposed
in the bit 10 for
supplying the lubricant to the bearing system S0, such as through a lubricant
passageway 68.
Any desirable number of reservoirs 62 can be disposed in a single leg 20 or
elsewhere in the bit
10. For example, Figure 20 shows a leg 20 having three reservoirs 62, while
Figures 15-17 show
lubricant reservoirs 62 disposed in the bit plenum 80. While the following
description of the
preferred embodiments of the present invention is made, in part, with respect
to a single reservoir
62, it may be applied equally to each reservoir 62 of a multiple reservoir leg
20, or bit 10.
To allow the insertion, or loading, of the lubricant and reservoir system
components into
the reservoir 62 during assembly of the bit 10, one end 76 of the reservoir is
initially left
accessible through a reservoir installation opening 63. After the lubricant
and reservoir system
components are inserted, or loaded, into the reservoir 62, the installation
opening 63 is typically
sealed and covered, such as, for example, with a reservoir cover cap 74 held
in place with a
retaining, or snap, ring 75 for retaining the lubricant and reservoir system
components in the
reservoir 62 (see also the prior art bit 10a of Figure 3). The opposite end 77
of the reservoir 62
typically forms a blind hole in the leg 20 (Figure 11 ).
Still referring to Figure 9, the reservoir 62 may contain various reservoir
system
components, such as, for example, a flexible membrane 64 that balances the
pressure between
the exterior 70 of the bit 10 and the lubricated, or lubricant carrying, side
66 of the bit 10. It
should be understood, however, that the inclusion or non-use of reservoir
system components in
the reservoir 62 is not limiting on the present invention.
As discussed herein, reservoir 62 can be pressurized or non-pressurized.
According to
one preferred embodiment, a pressurized reservoir is pressurized by pressure
communication
with the circulation fluid, either inside or outside the bit, through a
conduit 92. Any suitable
pressure-transmitting device, such as a plate, piston, diaphragm, or the like
can be positioned in
conduit 92 so as to transmit pressure from the desired circulation area to the
lubricant in the
reservoir 62, while maintaining the fluid in the reservoir in fluid isolation
from the circulation
fluid. In Figure 5, while installation opening 63 is on the trailing side of
the bit, conduit 92
communicates with the plenum. In Figure SA, conduit 92 again communicates with
the plenum,
but installation opening 63 is on the shoulder of the bit. In Figure SA, cover
95 in installation
opening 63 prevents any outward flow of fluid from chamber 93 and prevents
transmission of
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fluid pressure. Hence, fluid pressure from plenum 82 is transmitted through
conduit 92, across
flexible membrane 64 to reservoir 62.
In instances where the seals) protecting the bearing are susceptible to damage
by
excessive pressure, it is desirable to limit the pressure differential across
the seal(s). One method
of limiting the amount of pressure on the lubricant is to limit the pressure
drop across the nozzle,
which in turn limits the back pressure in the plenum. If flexible membrane 64
is in fluid
communication with the plenum (such as through a reservoir installation
opening in the plenum),
pressure in the reservoir will equal the pressure in the plenum. As long as
the difference between
the pressure in the plenum and the pressure in the annulus outside the bit is
less than the desired
amount, the seals) will not be subjected to excessive pressure. Control of
pressure in the
plenum is preferably accomplished by adjusting the nozzle exit orifice (nozzle
diameter). It has
been found through field experimentation that a pressure difference of 100
psig or less is
preferable and a pressure difference of 40 psig or less is optimum.
Alternatively, the lubricant
reservoir without requiring fluid communication with the plenum, such as by
the use a pressure
applying means, such as a spring-biased piston or the like.
Alternatively, excessive pressure across the seals) can be avoided by
balancing the
pressure on both sides of the seal so that the lubricant pressure is neutral
to the annulus pressure.
Placement of flexible membrane 64 in fluid communication with the annulus
(such as through a
reservoir installation opening in the annulus, e.g. on the leading face,
central panel, trailing face
or shoulder, as described below), pressure in the reservoir will equal the
pressure in the annulus.
Similarly, pressure in the lubricant reservoir can be balanced with the
pressure in the annulus,
regardless of where the reservoir installation opening is located.
Again referring to Figure 9, the reservoir system 60 may be also configured to
relieve the
expansion, or excess volume, of lubricant contained therein. Any suitable
technique or pressure
relief device as is or becomes known in the art may be utilized. For example,
the reservoir 62
can be configured such that there is sufficient space in the reservoir 62 for
the lubricant to
expand therein, as is known in the art. For another example, excess lubricant
in the reservoir
system 60 may be vented from the reservoir 62. Any suitable conventional
technique may be
used. For example, excess lubricant can be vented through the flexible
membrane 64, as is
known in the art. Another example of venting excess lubricant from the
reservoir system 60, as
shown in Figure 9, is through a vent duct 94 extending from the reservoir 62
to the bit exterior
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70, in accordance with the present invention. According to the present
invention, the opening of
vent duct 94 can be located on the throat surface, the leading surface, the
trailing surface, the
shoulder surface, or the center panel surface, although it is preferred that
the vent duct opening
not be on the same surface as installation opening 63. A control device, such
as a conventional
pressure relief valve 96, may be included to enable the controlled venting of
lubricant from the
reservoir system 60.
It should be understood that the aforementioned operations, configurations,
components
and methods have been provided to assist in understanding the context of the
invention and are
not necessary for operation of the invention.
Referring again to Figure l, each leg 20 of the bit body 12 of the bit 10 of
the present
invention includes a leading side 30, a trailing side 36, a shoulder 40 and a
center panel 46. The
leading side 30 has an outer surface 32, the trailing side 36 has an outer
surface 38, the shoulder
40 has an outer shoulder surface 42 and the center panel 46 has an outer
backturn surface 48.
Surfaces 32, 38, 42, 48 form part of the outer surface 100 of the leg 20. In
the embodiment
shown, for example, the leading side surface 32 extends generally from the
lower end 21 of the
connector 13 to the lower edge 26 of the leg 20 between the edges 45, 47 of
the center panel 46
and shoulder 40, respectively, and the edge 49 of the leg 20. The trailing
side surface 38 extends
generally from the lower end 21 of the connector 13 to the lower edge 26 of
the leg 20 between
edge 91 of the nozzle boss 90 and edges 43, 44 of the center panel 46 and
shoulder 40,
respectively. The shoulder surface 42 is shown extending from the lower end 21
of the connector
13 to the upper edge S 1 of the center panel 46 between the leading and
trailing sides 30, 36 at
edges 47, 44, respectively. Finally, the backturn surface 48 extends between
edges 45, 43 and 51
and the lower edge 26 of the leg 20.
Still referring to Figure 1, as the bit 10 rotates during operations, the
leading side 30 of
each leg 20 leads the clockwise rotational path of the leg 20 followed by the
shoulder 40 and
center panel 46, which are followed by the trailing side 36. During drilling,
as well as extraction
of the bit 10 from the bore hole 17 (Figure 2), the bit legs 20 will contact
earthen cuttings (not
shown) in the bore hole 17 and may also contact the bore hole wall 72 (Figure
2). Generally, the
leading side 30, leg shoulder 40 and center panel 46 of each leg 20 will
experience such contact,
while the trailing side 36 is substantially blocked from significant contact
with earthen cuttings
and the bore hole wall 72 by the surfaces 32, 42 and 48 and the leg mass 29.
Depending on
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various factors, such as the composition of the earthen formation being
drilled, contact between
the surfaces 100 of the legs 20 and earthen cuttings (and the bore hole wall)
will cause varying
degrees of wear and damage to the legs 20. During backreaming in hard, or
rocky, earthen
formations, for example, the legs 20, particularly the leg shoulders 40 and
leading sides 30, may
be subject to significant contact with rock cuttings, causing significant
erosive wear, cracking
and fracturing of the bit legs 20.
Referring to the prior art bit 10a of Figure 3, it is a concern that damage to
the bit legs 20
as described above can lead to damage to the lubricant reservoir 62, which can
lead to premature
bit failure. For example, the introduction of foreign material, such as
earthen cuttings, into the
reservoir or bearing systems 60, 50, will lead to contamination and
deterioration of the lubricant
and the reservoir and bearing system components, causing premature bit
failure. It is thus an
object of the present invention to provide improved protection of the
reservoir 62 and reservoir
opening 63 from damage caused by contact between the bit 10 and earthen
cuttings (and the bore
hole wall) during drilling and bit extraction.
In prior art bits 10a, as shown in Figure 3, the reservoir installation
opening 63 was
typically located on the leg shoulder 40, or across the intersection of the
shoulder and center
panel (not shown), facing angularly upwardly relative to the bore hole wall
72, or from the
central axis 11 of the bit 10a. For example, a typical prior art bit reservoir
opening 63 located on
the shoulder 40 was oriented with its axis at an angle 31 of about 75 degrees
or less relative to
the central axis 11 of the bit 10a. The prior art reservoir opening 63
orientation has been known
to subject the reservoir opening 63 and reservoir 62 to damage as described
above, particularly
during backreaming.
It should be understood that each of the following aspects of the invention
may be
utilized alone or in combination with one or more other such aspects. In one
aspect of the
invention, the installation opening 63 is accessible from the outer leg
surface 100, but located so
as to decrease the susceptibility of the reservoir 62 and opening 63 to damage
from contact
between the leg 20 and bore hole debris, or the bore hole wall 72 (Figures 4,
7, 8). The
installation opening 63 can be disposed anywhere on the leading side 30
(Figure 7), trailing side
36 (Figure 4) or center panel 46 (Figure 8). In accordance with this aspect,
as the bit 10 rotates in
the bore hole 17, particularly during extraction and backreaming, the
reservoir installation
opening 63 is generally more substantially blocked, or protected, from contact
with the bore hole
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wall 72 and earthen cuttings in the bore hole 17 by the leg mass 29, as
compared to the prior art
location of the installation opening 63 on the leg shoulder 40 (Figure 3). In
the preferred
embodiments shown, the reservoir installation opening 63 is disposed above the
bit throat level
22. The "bit throat level" 22 refers to the cross-section of each leg 20 and
the bit 10 taken
generally along line 27 (Figure 2), which extends proximate to the level of
the nozzle ports 86.
The "bit throat" 33, also shown in Figure 2, refers to the interior, or
facing, portions of each leg
20 between its lower edge 26 and the lower end 81 of the bit plenum 80.
However, the opening
63 may, in accordance with this aspect of the invention, also be disposed at,
or below, the bit
throat level 22.
In another aspect of the invention, the reservoir 62 may be oriented so that
the installation
opening 63 is on the outer surface 100 of leg 20, but is oriented on the
shoulder 40 (Figure 21) so
that its axis is at an angle 31 of between about 76 degrees and about 180
degrees relative to the
central axis 11 of the bit 10, or disposed at any angular orientation anywhere
on the leading side
30 (Figure 7), trailing side 36 (Figure 4), or center panel 46 (Figure 8) of
leg 20. For example,
the opening 63 in Figures 4 and 7 are on the trailing and leading sides 36,
30, respectively,
oriented generally perpendicularly relative to the central axis 11 of the bit
10, respectively. In
Figure 21, the opening 63 is oriented at an angle 31 of about 81 degrees
relative to the central
axis 11 of the bit 10.
1n a further aspect of the invention, as shown, for example, in Figures 4, 7
and 8, the
reservoir 62 and installation opening 63 may be isolated from contact with
bore hole debris and
the bore hole wall by recessing the installation opening 63 into the leg 20.
The reservoir opening
63 of the leg 20 of Figure 4, for example, is shown recessed into the trailing
side 36 of the leg 20,
while the opening 63 of Figure 7 is recessed in the leading side 30. In Figure
8, the reservoir
installation opening 63 is shown recessed into the center panel 46. The
installation opening 63
thus lies recessed relative to the shoulder and backturn surfaces 42, 48,
respectively, and is
shielded thereby and by the leg mass 29. Further, the leg 20 may be configured
so that the
shoulder 40 serves as a protective ledge above the installation opening 63, as
shown, for
example, in Figure 9. In Figure 9, the shoulder 40 extends radially outwardly
from the leg 20
toward the bore hole wall 72 relative to the reservoir opening 63 by a
distance 79 equal to
between about 50% and about 100% of the exposed radial dimension 78 of the
reservoir opening
CA 02330987 2001-O1-11
63, substantially blocking the reservoir opening 63 from contact with bore
hole debris during
backreaming.
In yet another aspect of the present invention, a protective plug 110 may be
emplaced
over the reservoir opening 63, as shown, for example, in Figures 7, 10-13. The
plug 110 protects
the installation opening 63 and reservoir 62 by serving as an outer contact
and wear surface and
by absorbing impact energy from contact with bore hole debris and the bore
hole wall 72 (Figure
11 ). The plug 110 may be any suitable size and configuration, and may be
constructed of any
suitable material having strength, or wear, characteristics similar to, or
better than, steel. For
example, refernng to Figure 13, the plug 110 may have a thickness 152 of about
10% or greater
of its diameter or smallest width 154. Any suitable technique may be used to
connect the plug
110 to the bit 10, such as by welding, matable members or mechanical
connectors (not shown).
Still referring to Figure 13, the bit 10 may be configured so that the plug
110 rests upon a plug
base 112 formed into the leg 20, whereby the base 112 absorbs energy from
impact force to the
plug 110 during drilling and bit extraction. Further, a gap 113 may be formed
between the plug
1 S 110, or plug base 112, and reservoir opening 63 to allow space for the
accumulation of excess
lubricant from the reservoir 62, or to isolate the reservoir 62 from the plug
110. A bleed hole (not
shown) may be formed in the plug 110, or the leg 20, and extends to the
exterior 70 of the bit 10
to allow the venting of excess lubricant from the gap 113.
Alternately, the installation opening 63 may be entirely isolated from the
outer surface
100 of the legs 20, as shown, for example, in Figures 14-18, to reduce the
susceptibility of
damage to the reservoir 62 and opening 63 from contact between the bit 10 and
bore hole debris
or the bore hole wall 72. Figures 14-17, for example, show the reservoir 62
configured so that
the reservoir opening 63 opens to the bit plenum 80. In Figure 14, the
reservoir 62 and
installation opening 63 are accessible via the plenum 80 and communicate with
bearing system
50 of leg 20, such as through lubricant passageway 68. The reservoir 62 is
shown as a reservoir
housing 65 disposed in a cavity, or receiving pocket, 69 formed in the leg 20.
The housing 65
may be any suitable container, such as a canister, having any form and
construction suitable for
use as a reservoir 62 as described above or as known in the art. When a
housing 65 is used, it is
inserted into the cavity 69 or otherwise formed into bit leg 20 during
assembly of the bit 10 and
may be connected to the bit 10 with any suitable conventional technique, such
as a threaded
matable connector 101, retaining rings, pins, or by weld (not shown). The
reservoir 62, however,
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need not be a housing 65, but can take other suitable forms. For example, the
cavity, or
receiving pocket, 69 can itself be used as the reservoir 62.
In Figures 15-17, the reservoir 62, such as housing 65 as described above, is
located
within the bit plenum 80. The reservoir housing 65 is mounted to the plenum
surface 82 with
pins 98 (Figure 15), brackets 99 (Figure 16, 16a) or any other suitable
conventional technique,
such as by weld or retaining rings (not shown). The reservoir 62 may be
capable of supplying
the bearing system 50 of a single leg 20, as shown, for example, in Figure 15,
or multiple legs
(Figures 16, 17). Further, the reservoir system 60, such as shown in Figures 1
S and 16, may
include tubes 104 that connect the reservoir 62 with the leg bearing systems
50, such as through
passageways 68. As illustrated in Figure 16a, the reservoir system 60 may have
numerous tubes
104 for supplying lubricant to numerous bit legs (not shown).
Referring to the embodiment shown in Figure 17, the reservoir 62 may be
located
generally proximate to the lower end 81 of the plenum 80 and in direct
communication with the
passageways 68 of legs 20 for supplying lubricant to the bearing systems 50.
The reservoir 62,
such as housing 65, may be easily installed into an assembled bit 10 by
inserting the reservoir 62
into the plenum 80 at the pin end 14 of the bit 10 and securing it with any
suitable conventional
technique, such as with a centralizing ring 120, or by weld. Alternately, the
reservoir 62 may be
easily installed through a bore 162 in the lower end 81 of the plenum 80.
Using this method,
once the reservoir 62 is positioned as desired, the bore 162 and reservoir 62
may be welded
together at the lower end 81 of the plenum 80 to secure the reservoir 62 in
the bit 10 and, if
desired, to substantially seal the plenum 80.
When the installation opening 63 opens to the bit plenum 80, such as shown in
Figures
14-17, the reservoir system 60 may be configured to allow the flow of
circulating fluid through
the entire length of the plenum 80. For example, a gap 88 (Figures 15, 16) can
be formed
between the reservoir 62 and the plenum surface 82. For another example, the
reservoir 62 can
include a fluid bypass annulus (not shown), such as when the reservoir 62 is
formed with a
donut-shape (not shown).
Excess lubricant may be vented from the reservoir system 60 with any suitable
technique,
such as those described above, if venting is desired. For example, excess
lubricant may be vented
through a vent passage 94 extending from the passageway 68 (Figures 14-16) to
the bit exterior
70. Excess lubricant may additionally, or alternately, be vented from the
reservoir 62 into the
12
CA 02330987 2001-O1-11
plenum 80 (Figures 15, 16) or to the bit exterior 70 (Figure 17), such as
through a vent hole 87 in
the reservoir housing 65. Further, the vent passageway 94 or vent hole 87 may
be equipped with
a control device, such as a pressure relief valve 96, to enable the controlled
venting of lubricant
from the reservoir system 60. The reservoir system 60 may also, or
alternately, be equipped with
a piston vent 138 (Figures 15, 16) disposed within the reservoir 62, or
housing 65. The piston
vent 138 includes a piston member 144 and biasing member, such as a spring
140, connected
between the cover, or end, 142 of the reservoir 62 and the piston member 144.
The piston
member 144 substantially sealingly engages the interior wall 160 of the
reservoir 62. Pressure
changes in the reservoir 62 will cause the piston member 144 to move upwardly
and downwardly
therein. When the pressure within the reservoir or housing 65 forces the
piston member 144
above a predetermined height, or level, of a bleed hole 150 in the reservoir
62 excess lubricant
and pressure in the reservoir system 60 is released into the plenum 80 through
the bleed hole
150. It should be understood, however, that the venting of excess lubricant
from the reservoir
system 60 with these or any other methods and structure is not required for,
or limiting upon, the
present invention.
In another configuration of the present invention, such as shown in Figure 18,
the
reservoir opening 63 is located in the proximity of the bit throat 33. The
reservoir 62
communicates with the leg bearing system 50, such as through passageway 68. By
opening to
the bit exterior 70 in the proximity of the bit throat 33, the reservoir 62
and reservoir opening 63
are isolated and protected from contact between the bit 10 and bore hole
debris and the bore hole
wall. The reservoir 62 is shown in Figure 18 having a housing 65 (as described
above) disposed
in a cavity, or receiving pocket, 69 formed in the leg 20. The reservoir 62,
such as the housing
65, may be connected to the bit 10 with any suitable conventional technique,
such as a threaded
mateable connector, retaining rings, pins, or by weld (not shown). The
reservoir 62, however,
need not include a housing 65, but can take any suitable form or
configuration. For example, the
cavity 69 can serve as the reservoir 62.
In a further aspect of the invention, a hard, wear resistant material 122 may
be
incorporated into, or upon, the bit 10 to strengthen the bit 10 and inhibit
erosive wear and contact
damage to the bit 10, reservoir 62 and reservoir opening 63, as shown, for
example in Figures 6
and 19. The hard wear resistant material 122 may have any suitable shape and
size and may be
set flush with (Figure 14), protrude from (Figure 9), or be recessed (not
shown) in the outer
13
CA 02330987 2006-06-09
surface 100 of one or more legs 20 of the bit 10, as is desired. Further, the
hard wear resistant
material 122 may be attached to the bit 10 with any suitable technique that is
or becomes known
in the art.
The term "hard wear resistant material" as used herein generally includes any
material, or
composition of materials, that is known or becomes known to have strength, or
wear,
characteristics equal to or better than steel, and which can be affixed onto,
or formed into, the
drill bit 10. The hard wear resistant material 122 may, for example, be
inserts 124 (Figure 4), as
are known in the art for strengthening and inhibiting wear to the bit 10.
Inserts 124 may also be
used for engaging and grinding loose rock in the bore hole during operations,
such as disclosed
in U.S. Patent Number 5,415,243 to Lyon et al. The inserts 124 may be tungsten
carbide inserts,
inserts constructed of a tungsten carbide substrate and having a natural or
synthetic diamond
wear surface, or inserts constructed of other suitable material. Any type of
insert that is, or
becomes, known for use with drill bits may be used with the present invention,
such as "flat-
top," dome shaped, chisel shaped and conical shaped inserts. The inserts 124
may be embedded
into the bit 10 as is known in the art or otherwise attached to the bit 10
with any suitable
technique. For another example, the hard wear resistant material 122 may be
hard facing, or
deposits 134, such as the guard member 136 of Figure 18. As shown in Figure
18, the hard
facing or deposits 134, such as the guard member 136, may itself carry inserts
124. The hard
facing or deposits 134 are applied to the bit 10 with any suitable technique,
such as by being
brazed or welded thereto.
The hard wear resistant material 122 can be placed at any location on the bit
10 as is
desirable for assisting in protecting the reservoir 62 and reservoir opening
63. As shown, for
example, in Figures 14 and 18, the material 122 can be located on the bit 10
outward of the entire
reservoir system 60 relative to the bore hole wall 72. Figure 14 shown inserts
124, while Figure
18 shows guard member 136, each located on the shoulder 40 to assist in
protecting the reservoir
62 and reservoir system 60 located within the leg 20. For another example,
hard wear resistant
material 122, such as inserts 124, can be embedded into, or attached to, the
plug 110 of the
present invention, such as shown in Figures 7, 10-13.
When the reservoir installation opening 63 opens to the leg surface 100, hard
wear
resistant material 122 may be used to protect the reservoir 62 and
installation opening 63. For
example, a protective ledge, or protrusion, 126 of hard wear resistant
material 122, such as
14
CA 02330987 2001-O1-11
shown in Figure 6, may be strategically formed into or attached to the leg 20,
such as above or
around the installation opening 63. The protrusion 126 may be connected to the
bit 10 with any
suitable conventional method, such as by welding or mechanical attachment
means (not shown).
For another example, hard wear resistant material 122, such as inserts 124,
may be placed
anywhere on the outside surface 100 of the leg 20 to assist in protecting the
reservoir 62 and
installation opening 63 (Figures 6, 12). Figures 4 and 7 shows the use of hard
wear resistant
material 122, such as inserts 124, on the shoulder 40 and center panel 46 when
the installation
opening 63 is on the trailing and leading sides 36, 30, respectively. Figure
20 illustrates an
example of the use of inserts 124 in conjunction with a leg 20 having two
reservoir openings 63
on the shoulder 40 and a third installation opening 63 on the trailing side
36. Other examples of
legs 20 having inserts 124 on the surface 100 when the installation opening 63
is on the shoulder
40 are shown in Figures 12, 13 and 19. In Figure 6, the installation opening
63 is shown located
at the intersection of the shoulder 40, center panel 46 and trailing side 36
of the leg 20 within a
protrusion 126. Hard wear resistant materials 122, such as inserts 124, are
strategically disposed
1 S on the leg 20, such as on the shoulder 40 and center panel 46, to protect
the reservoir 62 and
installation opening 63. Figures 8 and 11 show examples of the use of hard
wear resistant
material 122, such as inserts 124, to assist in protecting the reservoir 62
and installation opening
63 when the installation opening 63 is on the center panel 46. It should be
understood, however,
that the particular arrangements, locations and quantities of hard wear
resistant material 122,
such as inserts 124, shown in the appended drawings are not limiting on the
present invention.
Each of the foregoing aspects of the invention may be used alone or in
combination with
other such aspects. While preferred embodiments of the present invention have
been shown and
described, modifications thereof can be made by one skilled in the art without
departing from the
spirit or teachings of this invention. The embodiments described herein are
exemplary only and
are not limiting of the invention. Many variations and modifications of the
embodiments
described herein are thus possible and within the scope of the invention.
Accordingly, the scope
of protection is not limited to the embodiments described herein.
