Note: Descriptions are shown in the official language in which they were submitted.
383~
Backgr_und_of the Invention
1. Field of the Invention
_
The present invention pertains to devices, such as trans-
ducers, or the electrical rneasurement of non-electrical quan-
tities. More particularly, the present invention is related totechniques for measuring the speed and/or direction of rotation
of bodies. This invention finds particular application in the
determination ofdirection and rate of fluid flow in wells, such
as oil and gas wells.
2. Description of the Prior Art
Methods currently utilized for measuring the speed and/or
direction of rotation of bodies are embodied in both mechanical
and electrical devices. The accurate measurement of speed and
direction of rotation is useful in a number of different
applications, including oil field exploration and development.
Common techniques of measurement of shaft rotation, for
example, through mechanical me~hods include attaching a uni-
versal gear to the body of the shaft and connecting various
gearing arrangements to that universal gear to operate an
indicator. Similarly, mechanical tripping counters can also be
used to count the number of revolutions per preset period of
time. Inherent in such prior mechanical devices are problems
that affect the accuracy of measurement. Such devices produce
drag upon the shaft. This can slow the speed of rotation or
waste energy overcoming that drag. Secondly, such mechanical
devices cannot be isolated from the object of their measure-
ment, leaving such devices possibly susceptible to corrosion
and mechanical failure. Finally, these mechanical devices can
be costly to manufacture and difficult to assemble.
An alternative to mechanical measuring devices is pro-
vided by electrical measurement of rotation using magnetic
proximity detectors or phase shift coils, for example. Such
apparatus do not, however, detect the direction of rotation of
a body.
A magnetic proximity detector employs a dc-operated elec-
tromagnet whose field flux is altered by variations in the
structure of a shaft rotating adjacent the magnet. In the case
of slowly rotating shafts, the low flux change rate is difficult
3.~9
to read. Further, the dc-type magnetic field imposes a drag on
the shaft that may significantly alter the rate of rotation of
the shaft in an otherwise relatively friction-free environ-
ment.
A phase shift coil detector depends upon the inductance of
its coils, and cornpares a reference signal with a signal phase-
shifted by the effects of a rotating body adjacent one of the
coils. Information obtained using a phase-change technique is
generally less reliable than that obtained by way of amplitude
modulation, for example, particularly at relatively high tem-
peratures where the coil inductance may be altered.
It is desirable to provide low cost, accurate and drag-
free apparatus for measuring both speed and direction of
rotation of bodies. In many settings, a high temperature
rating, a linear output to zero rotation rate, and resistance
to the effects of vibration are essential. The present inven-
tion offers such advantages over both prior mechanical and
electrical techniques.
1'~3~
Summary of the Invention
The present invention provides apparatus for sensing
motion including a detector having a primary, or exciter, coil
for generating an electromagnetic signal, and at least one
secondary, or pickup, coil for receiving the electromagnetic
signal and providing output signals. At least two zones of
differing magnetic effect provide magnetic encoding, or key,
means, and are movable with the motion to be sensed. The
encoding and the detector are so configured that, when the zones
are so moving, such a zone of relatively high magnetic effect
passes adjacent the combination of the primary coil and at least
part of one of the secondary coils to cause an increase in the
output signal provided by the secondary coil compared to the
output signal so provided when a zone of relatively low magnetic
effect passes adjacent the same combination. The juxtaposition
of a zone of relatively high magnetic effect adjacent the coil
combination tends to close a magnetic flux linkage to produce
the electromagnetic signal enhancement, while the juxtaposi-
tion of a low magnetic effect zone adjacent the coil combi-
nation is sensed as a relative opening of the flux linkage withthe resulting relative low electromagnetic signal.
The magnetic encoding may be provided, at least in part,
by material of relatively high permeability to provide zones of
relatively high magnetic effect, that is, zones capable of
effecting relatively large flux linkages, and by material of
relatively low permeability to provide zones of relatively low
magnetic effect, that is, zones capable of effecting generally
lesser or no flux linkage. The magnetic encoding means may also
be provided, at least in part, by the configuration of the
~magnetic material of the encoding whereby movement of the
encoding means relative to the detector effects variation in
the relative displacement between the magnetic material and the
detector so that relatively small displacements provide zones
of relatively high magnetic effect, and relatively large dis-
placements provide zones of relatively low magnetic effect. Acombination of materials of differing permeability and such
materials arranged to vary the displacements oE same relative
to the detector may be utilized to provide the magnetic en-
- 5 - 1~3~;3~9
coding.
Variations in the amplitude of the electromagnetic signal
due to the rotation of the magnetic key zones by the coil
combination may be noted and counted as a function of time to
determine the rate oE movement of the zones by the detector.
Two sets of secondary coils, used in combination with two sets
of zones, may be used to produce two detector signals of varying
amplitude to permitdetermination oEthe rate of mov~ment of the
zones as well as ~he direction of such movement, the latter
being determined by the phase relationship of the data signal
variations in relation to mutual displacement of the two sets
of zones.
The magnetic encoding may be provided on a shaft whose
rotation is to be measured, as in a spinner transducer. The
shaft may be constructed of generally non-magnetic, or low
permeability material, for example, with a pattern of longi-
tudinally-extending deposits, such as strips, of magnetic, or
high permeability material arranged in circumferential array
about the shaft. S~ch strips may be formed, for example, by
positioning magnetic material inserted within grooves cut into
the shaft, or by attaching projections of magnetic material
along the shaft. In the latter case, the shaft proper may ~e
either of magnetic or non-magnetic material, and the proiec-
tions may be either solid magnetic material, or coated with
magnetic material. Another method of providing the magnetic
coating is to construct at least a portion of the shaft with
flat surfaces separated by longitudinally-extending edges.
The shaft may then be solid magnetic material, coated with
magnetic material, or constructed of non-magnetic material
with the edges being magnetic. A shaft made of magnetic
material may be provided with a pattern of grooves so that the
displacement of magnetic material of the shaft relative to the
detector varies as the shaft rotates.
The detector includes a core on which is mounted the
exciter coil and at least one secondary, or pickup, coil. The
detector is positioned adjacent the coding on the shaft so that
rotation of the shaft causes movement of the magnetically coded
shaft portions by the detector. Such passage of the coded
portions of the shaft by the detector tends to close a flux
linkage between the exciter coil and the pickup coil, while
juxtaposition of the non-magnetic portion of the coded section
of the shaft at the detector tends to open the flux linkage
between the pickup coil and the exciter coil. The alternate
opening and closing of the flux linkage as described causes
fluctuations in the amplitude of the electromagnetic signal
produced in the pickup coil in response to an electromagnetic
signal impressed on the exciter coil. The amplitude modulation
of the pickup coil signal reflects the rate of rotation of the
shaft.
A second magnetic coded section may be provided on the
shaft, generally longitudinally displaced from and circum-
ferentially displaced relative to the first magnetic coding
section of the shaft. A second pickup coil is provided on the
same core and positioned so that the magnetic coding of the
second portion of the shaft alternately opens and closes a flux
linkage between the second pickup coil and the exciter coil as
the shaft rotates. Thus, a second amplitude modulated signal
is produced in the second pickup coil, and may also be noted for
determination of the rate of rotation of the shaft. The
circumferential displacement between the two coded sections of
the shaft, in cooperation with the pickup coils being longi-
tudinally aligned along the shaft with the exciter coil,
produces a pair of electromagnetic amplitude modulated signals
which are mutually phase-shifted depending on the direction of
rotation of the shaft. This phase shifting in the signals is
due to the leading or lagging of one magnetic encoding set on
the shaft relative to the other in passage by the respective
exciter coil/pickup coil flux loops.
An alternating electronic signal may be employed to drive
the exciter coil to produce alternating magnetic fields through
the pickup coils. Rotation of the shaft relative to the coils
then produces amplitude modulated alternating magnetic fields.
The resulting electronic data signals from the pickup coils are
then amplitude modulated ac electronic signals which include a
carrier component whose frequency is dependent solely on that
of the oscillator of the exciter circuit producing the input to
1~3~3~
--7--
the exciter coil, but whose frequency of amplitude modu-
lation is dependent on the rate of rotation of the shaft.
The mutual phase shift between the pickup coil output
signals may be readily determined. Consequently, both
direction and rate of rota~ion of the shaft may be as-
certained by analysis of the amplitude modulated signals
from the pickup coils, and comparison thereof.
~ ince the present invention employs alternating
electronic signals to produce alternating magnetic fields
whose amplitude modulation is utilized to obtain the
desired motion information, such motion information is
impervious to, for example, frequency drift of the car-
rier signal, or vihration of the rotating shaft in such
application. The output signals may be processed to ob-
tain pulsed dc signals, which may be readily analy~ed bythe counting of the pulses and the notation of the rela-
tive phase shift between the two pulse signals from the
two pickup coils. The use of varying the alternating
magnetic fields in the detector results in virtually
no drag due to magnetic field linkage between the mov-
ing body, such as a rotating shaft, and the detector.
Further, since the detection technique relies on ampli-
tude modulation, which may be enhanced electronically if
necessary, the detector mechanism may be non-magnetically
isolated from the moving body, particularly where such
body may be subjected to an environment which could be
corrosive or otherwise detrimental to the detector mec-
hanism. The core of the detector mechanism may be rnade
of a single, solid piece of fe.rrite material, rendering
a high and flat inductance up to a significantly high
temperature.
In a particular embodiment illustrated, a spinner
transducer tool according to the present invention is
incorporated in a flow measuring device which finds
particular application in determining rate of flow of
~ ~3~3~9
-7a-
fluids along wells. The encoding portion of the spinner
transducer tool is included on the shaft of an impeller
which is caused to rotate by fluid flowing through the
flow measuring device. The detector portion of the
S spinner transducer tool, as well as the electronic
circuitry needed to power the detector and to analyze
the output signals from the pickup coils, are fluid-
isolated from the magnetically
keyed shaf t. 123~3389
-Y- ~38389
Brief Description of the Drawings
Fig. 1 provides a horizontal elevation in partial section
of a fluid flow measuring device incorporating a spinner
transducer tool according to the present invention, and in-
cludes Figs. lA, lB, lC, lD and lE illustrating sections Or themeasuring device in sequence from top to bottom, respectively,
with the scale of Fig. lE reduced;
Fig~ 2 is a horizontal elevation, partly schematic, of a
portion of one version of the spinner transducer tool, par-
ticularly illustrating the alignment of the detector mechanismin relation to a groove-encoded shaft;
Fig. 3 is a cross-sectional view of the shaft taken along
line 3-3 of Fig. 2, showing an embodiment of the invention
having non-magnetic shaft material and grooves containing
magnetic material;
Fig. 3A is a view, similar to Fig. 3, of the shaft showin~
an embodiment of the invention having magnetic shaft material
and open grooves, or grooves containing non-magnetic material
(not shown);
20Fig. 4 is a perspective view of the detector mechanism;
Fig. 5 is a horizontal elevation of a portion of another
embodiment of the spinner transducer tool, particularly illus-
trating the alignment of the detector mechanism in relation to
a flat-encoded shaft;
25Fig. 6 is a cross-sectional view of the shaft with flats
taken along line 6-6 of Fig. 5;
Fig. 7 is a horizontal elevation of a portion of another
embodiment of the spinner transducer tool, particularly illus-
trating the alignment of the detector mechanism in relation to
a projection-encoded shaft;
Fig. ~ is a cross-sectional view of the shaft with pro-
jections taken along line 8-8 of Fig. 7;
Fig. 9 is a fragmentary cross-sectional view of the
groove-encoded shaft of Fig. 2, further illustrating a thin
wall barrier between the shaft and the detector mechanism;
Fig. 10 is a perspective view of the detector mechanism
core with beveled pole faces for flux focusing;
Fig. 11 is a block diagram of electronic exciter circuitry
-- 1 u ~ 3~3~3~
for providing the input electronic signals to the detector
meehanism;
Fig. 12 is a block diagram of electronic data reduetion
eircuitry for interpreting the output signals from the deteetor
mechanism; and
Fig. 13 is a timing diagram for comparing the output
signals from the two pickup coils, both before and after the
signals are processed.
3~3~9
Detailed Description of the Preferred Embodiments
A spinner transducer tool in accordance with the present
invention is shown in part generally at 10 in Fig. lD in
operating position within a fluid flow measuring device which
is illustrated generally at 11 in Figs. lA-lE. The spinner
transducer tool 10 is shown in detail in part in Figs. 2, 3 and
4. The spinner transducer tool 10 generally includes four major
components: a generally cylindrical shaft segment 12, a
detector or sensor mechanism 14, and exciter circuit, shown
schematically at 15 in Fig. 11, and a pulse-counting circuit,
which is shown schematically at 16 in Fig. 12. In mutual
cooperation, these elements may serve to determine the speed
and direction of rotation of the shaft 12 and equipment attached
thereto.
The shaft 12 is rotatably mounted within the fluid flow
measurement device 11 as described rnore fully hereinafter, and
is magnetically encoded to provide rotation information to the
detector mechanism 14. The encoding may be achieved in a
variety of ways.
As may be appreciated by reference to Fig. 2, the shaft 12
has one or more grooves 20 located in each of two axially spaced
sets shown generally at 22 and 24 on the shaft. The groove sets
22 and 24 are separated by a shaft region shown generally at 25.
The grooves 20 may be formed by milling, casting, or any other
appropriate method. Each set 22 and 24 has four grooves 20
spaced at equidistant locations along the circumference of the
shaft 12, as illustrated in Fig. 3. The number of grooves 20
is not critical to the invention, but both groove sets 22 and
24 preferably include the same number of grooves, and such will
be considered hereinafter. It is preferable that all grooves
20 be the same shape and size. Further, the grooves of one set
22 are circumferentially displaced, or offset, from the grooves
of the other set 24 as shown. The offset may be measured from
the centers of the grooves 20, or in any other convenient
manner. These various features of the grooves 20 are dictated,
in part, by the diameter of the shaft 12.
The circumferential displacement, or offset, between the
grooves 20 of the two sets 22 and 24 is generally equal to one-
-12- .~3~;3~`~3
fourth of the circumferential displacement between consecutive
grooves in each set. As described more fully hereinafter, the
passage of each groove 20 by the sensor 14 during rotation of
the shaft 12 is accompanied by the generation of an electronic
pulse, with each set of grooves 22 and 24 thus providing a
separate electronic signal comprising a stream of pulses. If
the shaft rotation rate is constant, the signal pulse rates are
constant with the grooves 20 equally-spaced about the shaft 12
in each set 22 and 24. For each signal, the period defined by
consecutive pulses is equal to the time between passage of
consecutive grooves 20 in the corresponding groove set 22 or 24
by the sensor 14. This time and, hence, the circumferential
distance between consecutive grooves 20 in a set 22 or 24, may
be described as a 360 phase. Thus, a 90 phase delay or shift
in the electronic signal generated by a groove set 22 or 24
corresponds to one quarter of the distance along the circum-
ference between consecutive grooves in the set of grooves.
Then, with the grooves of one set 22 or 24 circumferentially
offset from the grooves in the other set by one quarter the
circumferential distance between consecutive grooves in each
set, the electronic signals of pulses produced by the two groove
sets passing by the sensor 14 will be 90 out-of-phase, with one
signal leading or lagging the other, depending on the relative
orientations of the two groove sets ~which one "leads" the other
on the rotating shaft 12) and on the direction of rotation of
the shaft, as discussed more fully hereinafter.
The number of grooves 20 within each set 22 and 24 will be
determinative of the circumferential offset distance to a-
chieve the 90 phase difference between the electronic signals.30 For example, if there is only one groove 20 per set, then the
groove in set 22 must be offset one quarter of the circumference
of the shaft 12 from the groove in set 24, or along an arc
subtended by a 90 central angle of the cylindrical shaft.
Howeverl if there are four grooves 20 within each set as
illustrated, then the grooves in set 22 must be offset from the
grooves in set 24 through a 22.5 central angle. Generally, the
grooves are wide enough so that there is an overlap in time~ f
pulses generated by corresponding, 90-shifted grooves of the
~3~33~3
two sets. For example, as viewed in Fig. 2, the left edge 26
of a groove 20 within the upper set 22 is preferably farther to
the left than the right edge 28 of the corresponding groove
within the lower set 24 to achieve the desired signal pulse
overlap. This pulse overlap is utilized for a determination of
rotation direction, as explained below. The depth and length
of each of the grooves 20 is dependent upon the size and
sophistication of the detection mechanism and the pulse count-
ing equipment, as also discussed further hereinafter.
The shaft 12 is encoded with magnetic material. One
technique, as shown in Fig. 3, is to provide the grooves 20 in
a shaft made of non-magnetic material. Magnetic filler ma-
terial 29 is used to fill each of the grooves 20. An alter-
native, as shown in Fig. 3A, is to make the shaft 12' of magnetic15 material and retain the grooves 20 empty. In such case,
however, the grooves 20 may be filled with non-magnetic ma-
terial (not shown), such as epoxy, to maintain shaft balance for
high speed rotation, and to provide a smooth, continuous
surface for non-turbulent fluid flow in a fluid flow measuring
device such as 11 as shown. Regardless of the manner of
encodinq, the changes in the magnetic properties of the shaft
passing adjacent the sensor 14 cause generation of the pulse
signals. Thus, the sensor 14 "sees" the non-magnetic shaft 12
of Fig. 3 for relatively long periods separated by relatively
short periods with the magnetic material 29 in the grooves 20
adjacent the sensor, wherein the pulses are generated. Alter-
natively, the sensor 14 "sees" the magnetic shaft 12' of Fig.
3A for relatively long periods broken by relatively short
periods with the grooves 20, either hollow or containing non-
magnetic material, adjacent the sensor, wherein "negative
pulses," or amplitude reductions, are effected. In either
case, the variation in relative position of magnetic material
with respect to the sensor 14 affects the sensor and related
circuitry (Fig. 12) to produce the pulsed signals.
In Figs. 5 and 6, another embodiment of the spinner
transducer tool is indicated. A shaft 12a in this embodiment
has flats 30 formed about the circumference of the shaft in two
axially spaced sets, shown generally at 32 and 34, separated by
-14-
a cylindrical portion 36. It is preferable that each flat area30 within each set 32 and 34 is of the same length and width as
those of every other flat within the set, and that the flats in
a set occupy the entire circumference of the shaft 12a defining
longitudinally extending edges 38 positioned equidistant about
the shaft circumference. While Figs. 5 and 6 show six flat
areas 30 within a set, the number of flats is not critical to
the invention. More or fewer flats may be incorporated de-
pending on the capability of the detection mechanism or or. the10 need for accuracy of measurement. However, it is preferable
that both sets of flats 32 and 34 be of identical form, that is,
include the same number of flats 30, with all flats being of the
same configuration.
As in the case of the embodiments of Figs. 2-3A, the sets
of flats 32 and 34 are mutually circumferentially offset as
indicated in Fig. 6. Again, the degree of the circumferential
offset is generally one quarter the circumferential distance
between consecutive edges 38 in one set 32 or 34 to achieve a
90 phase shift, both structurally as illustrated, and in the
electronic signals produced by rotation of the two sets 32 and
34 by the sensor 14 as discussed more fully hereinafter. In the
case of six flats 30 in each set 32 and 34, each edge 38 in one
set is offset by a central angle of 15 from a corresponding
edge in the other set as indicated in Fig. 6.
The embodiment of Figs. 5 and 6 requires that the shaft
12a, or the surface of the shaft, or at least the edges 38, be
made of a magnetic material. Then, the variation of distance
between the sensor 14 and the magnetic material carried by the
shaft 12a in any such configuration, as the shaft rotates,
affects the magnetic sensor to cause the pulse signal genera-
tion by tending to alternately open and close flux links in thesensor.
A fourth embodiment of the present invention is indicated
in Figs. 7 and 8. A shaft 12b has longitudinally-extending
projections 40 arranged about the circumference of the shaft.
The projections 40 may be attached to the shaft 12b by sold-
ering, welding, or any other rigid mountinq method, or may be
integral with the shaft. The projections 40 occur in two sets
L5 ~ 9
shown generally at 42 and 44. Preferably, in each set 42 and
44 all the projections are of the same size and shape, and are
arrayed equidistant about the circumference of the shaft 12b.
The number of projections 40 in each set 42 and 44 is not
critical to the invention, and may be as low as 1, but it is
preferred that both sets have the same number, construction and
con~figuration of projections.
The two sets 42 and 44 of projections are generally
mutually axially displaced, but overlap longitudinally in a
middle area shown generally at 46 with the bottom ends 48 of
projections in the upper set 42 extending below the top ends 49
of projections within the lower set 44. The two sets of
projections are mutually circumferentially offset by a quarter
of the circumferential distance between consecutive projec-
lS tions 40 in either set to achieve the spatial and electronic so
phase difference as described herein. With four projections 40
in a set, the circumferential offset subtends a central angle
of 22.5 as indicated ln Fig. 8.
The pro]ections 40 are constructed of, or are at least
covered with, magnetic material, and may be formed on a shaft
12b made of either magnetic or non-magnetic material. The
region about the circumference of the shaft 12b and between
consecutive projections 40 of each set 42 and 44 may be filled
with non-magnetic material (not shown) to provide a smooth,
cylindrical shape to ensure shaft balance and/or non-turbulent
fluid flow along the shaft, as discussed before relative to the
embodiment of Fig. 3A. ~s in the previously-described cases,
the variation in distance between the sensor 14 and the magnetic
material of the shaft 12b as the latter rotates near the sensor
affects the sensor to produce pulsed electrical signals, whe-
ther the shaft proper is magnetic or non-magnetic.
The encoded shaft segment of the transducer 10 is not
limited to the above-described embodiments, but may employ any
configuration of magnetic coding which varies the displacement
of one or more concentrations of magnetic material, carried by
the shaft, relative to the sensor 14 as the shaft is rotated
relative to the sensor. To enhance the ability of apparatus
according to the invention to determine rotational speed, the
3~3~
configuration of magnetic material c~using such variation in
displacement should occur at uniform intervals about the cir-
cumference of the shaft. If speed information is required, but
not directional information, then the shaft may have only one
set of grooves, flats, or projections, rather than two.
The detection mechanism 14 acts as a sensor for detecting
the flats (edges), grooves (fill), or projections of the
magnetic coding. The detector 14 includes three major com-
ponents: a core 50, an exciter coil 52, and two pickup coils
54 and 56 on opposite sides of the exciter coil (see Fig. 4).
The detector 14 senses variations in distance between thepickup coils 54 and 56, in combination with the exciter coil 52,
and the magnetic coding material on the shaft encoded segments.
The core 50 is in the form of an "E" with a center leg 57
and end legs 58 and 59, and is preferably made of a single, solid
piece of ferrite material. The coils 52, 54 and 56 are
positioned on the legs 57, 58 and 59, respectively, as shown in
Fig. 4. Such a core 50 features a high and flat inductance up
to 235C. This feature is particularly advantageous in oil well
drilling and exploration activities where downhole tempera-
tures will frequently rise to this level. Furthermore, even
when the temperature rises above 235C and the core 50 starts
to lose its inductance, the inductance within the single-piece,
ferrite core will return to normal upon the lowering of the
temperature. Thus, the single-piece rerrite core 50 is pre-
ferable to a laminated core, for example.
As illustrated in Figs. lD, 2, 5 and 7, the detector 14 is
positioned generally parallel to the shaft 12 (12', 12a or 12b),
with the exciter coil 52 and leg 57 aligned with the shaft
region 25 or 36 between encoding sets 22 and 24, or 32 and 34,
respectively, or with the projection overlap area 46 of the
projection sets 42 and 44. The pickup coils 54 and 56, on legs
58 and 59, respectively, are aligned with the upper and the
lower encoding sets, respectively (22 and 24; 32 and 34; or 42
and 44). The exact configuration of the detector 14 relative
to the shaft (in any form) is not critical to the proper
functioning of the present invention, and may be varied.
However, in general, the distance between the shaft and the
-17~ 3~9
detector 14 may affect the strength of data signals ulti-
mately produced in the pickup coils 54 and 56 with greater
signal strength achieved by reduction of the distance. The
effect of the rotating coded shaft on the sensor 14 in causing
the generation of pulse signals is, in general, increased as the
lateral distance between the shaft and the sensor is decreased.
But this distance may be kept sufficiently large to allow a thin
wall 60 of non-magnetic material to mechanically isolate the
shaft from the sensor, as shown in Fig. 9 and as discussed more
fully below.
The "E" core 50 may be considered as including two "C"
cores, each comprising the central leg 57 carrying the exciter
coil 52, and one or the other of the end legs 58 or 59, with the
corresponding pickup coil 54 or 56, respectively. The exciter
circuitry ]5 (Fig. 11) includes an ac, or sine wave, generator
62 which provides an output ac signal with a frequency in the
range of 10-100 kHz, for example, though the specific frequency
is not critical to the invention. The sine wave signal is
enhanced by a driver 64, providing signal C, for transmission
along appropriate conductors 66 to the exciter coil 52. The
changing electromagnetic field associated with the ac signal C
thus impressed on the exciter coil 52 produces alternating
magnetic fields in the "E" core 50, and through each end leg 58
and 59, and the respective pickup coil 54 and 56. In each case,
the magnetic material carried by the rotating shaft tends to act
as a shunt to close the magnetic flux path across the respective
"C" core, thus increasing the magnetic linkage between the
exciter coil 52 and the pickup coil in question. The flux path
in each case is opened again as the shaft rotates, lessening the
magnetic flux, generated b~ the exciter coil 52, that links the
corresponding pickup coil.
The legs 57-59 of the "E" core 50 may be beveled, or
otherwise shaped, at the pole faces formed by the ends thereof
as shown at 67 in Fig. 10 to concentrate the magnetic flux at
the faces. With the flux thus focused, the variation in flux
linkage as the magnetic coding of the shaft passes by the sensor
14 with shaft rotation may be more pronounced, yielding greater
signal modulation produced by the sensor. Where the con-
3~33~g
struction of the shaft is such that the magnetic coding is moredistinct, as in the case of the grooves 20 filled with magnetic
material 29 (Figs. 2 and 3) for example, such focusing by pole
face shaping is not essential. For less radical coding, as in
the case of the shaft 12' of magnetic material with grooves 20
containing no magnetic material, the variation in flux linkage
with shaft rotation may be suitably enhanced by focused-field
pole faces as shown in Fig. 10.
The ac signal C impressed on the exciter coil 52 will
always be received by each of the pickup coils 54 and 56, but
the amount, or amplitude, of signal received by each pickup coil
is increased when the flux linkage is "closed" by the posi-
tioning of magnetic material carried by the shaft adjacent the
opening in the respective "C" form of the core S0, the signal
received by the pickup coil in question decreasing in amplitude
as the magnetic material is rotated away to "open" the flux
linkage across the "C". The number of turns and the wire size
included in the exciter coil 52 affect its inductive reactance,
and, therefore, the strength of the signal available at the core
50. The number of turns in each pickup coil 54 and 56
determines, in part, the signal level receivable by these coils
for modulation by the magnetic coding of the shaft. In both
cases, the signal response of the sensor 14 is increased with
an increase in coil windings. Typically, a well responsive
transducer may be provided according to the present invention,
with a solid ferrite core 50, generally with 200 windings in
each coil 52-56, in contrast to the approximately 1,000 wind-
ings that might be required in conjunction with a laminated
core.
Since the signal generated by the oscillator 62 and
impressed on the exciter coil 52 is, in general, an alternating
current sine wave, the resulting magnetic flux signal linking
the exciter coil with the two pickup coils 54 and 56 is also an
alternating signal, with the magnetic field periodically
changing direction at a relatively rapid rate. Consequently,
the magnetically-encoded rotating shaft 12 experiences little
or no magnetic drag~ as opposed to the magnetic drag which may
be exerted on a rotating shaft in the case of magnetic proxi-
- 1 9 - ~ 3~3~3~
mity or phase shift detectors which utilize constant magnetic
fields.
In operation, the shaft may generally rotate in either a
clockwise or a counteeclockwise direction. As noted herein-
before, as the shaft rotates adjacent the sensor 14, magneticmaterial carried by the shaft passes by each of the pickup coils
54 and 56, tending to close, or shunt, a loop in the core 50
including the exciter coil 52 and the respective pickup coil.
When either core loop is thus shunted, the sinusoidal signal
generated in the respective pickup coil 54 or 56 increases in
amplitude. As the shaft continues to rotate, and the linkage
between the pickup coil in question and the exciter coil 52 is
again opened by the removal of magnetic coding material from the
immediate vicinity of the sensor 14, the amplitude of the signal
induced in the respective pickup coil is reduced accordingly.
Thus, in the case of the non-magnetic shaft 12 with two sets 22
and 24 of grooves 20 filled with magnetic material 29 (Figs. 2
and 3), it is the passage of the magnetic filler material 29
adjacent the sensor 14 which shunts the core 50 to increase the
amplitude of the signal induced in the correspondiny pickup
coil. In the case of the shaft 12' constructed of magnetic
material, and carrying grooves 20 that are either empty or
filled with non-magnetic material (Fig. 3A), the proximity of
the cylindrical surface of the magnetic shaft between the
grooves 20 causes the amplitude in the corresponding pickup
coil signal to be relatively large, and the positioning of the
non-magnetic grooves 20 adjacent the core 50 results in ampli-
tude reduction. The magnetic material of the edges 38 of the
shaft 12a (Figs. 5 and 6) adjacent the core 50 results in signal
amplitude increases, while orientation of the flats 30 adjacent
the sensor 14 is coincident with increased displacement of mag-
netic material from the core 50 to cause a reduction in signal
amplitude. Finally, the magnetic projections 40 carried by the
shaft 12b (Figs. 7 and 8), adjacent the core 50, cause increased
signal amplitude at the pickup coils, while rotation of the
shaft to remove the projections from the vicinity of the sensor
14 results in reduced signal amplitude at the pickup coils.
The exciter coil 52 is positioned aligned with the cylin-
-20- ~ ~3~3~9
drical shaft portion 25 in the two versions of the shaft which
include the grooves 20 (Figs. 2, 3 and 3A), including the case
of the non-magnetic shaft 12 with the magnetic filler material
29 residing in the grooves and the case of the magnetic shaft
12' with the empty, or non-magnetic, grooves 20. Wi-th the
magnetically-filled grooves of the non-magnetic shaft 12
(Figs. 2 and 3), the magnetic material 29 is suff~iciently
concentrated that the distinction between the closed~configu-
ration, wherein the magnetic material is adjacent the sensor
14, and the open configuration wherein the magnetic material
has been rotated out of such configuration, is sufficiently
great to provide amplitude modulation of relatively high sig-
nal-to-noise ratio.
In the case of the magnetic shaft 12' and non-magnetic
grooves 20 (Fig. 3A), as well as the variation including a
magnetic shaft 12a with Çlats 30 and edges 38 (Figs. 5 and 6),
wherein the exciter coil 52 is always facing magnetic material,
such as the cylindrical surface 36 in the case of the flats-and-
edges version, the flux linkage closing when the magnetic
material is closest to the sensor 14 is enhanced by the exciter
coil being adjacent magnetic material to permit relatively
large signal amplitude at the respective pickup coil 54 or 56.
If necessary, the distinction between such linkage, in the
closed configuration, and the open configuration, wherein the
grooves 20 or flats 30 are adjacent the core 50, but with the
exciter coil 52 still facing magnetic material in the cylin-
drical poetions 25 (Figs. 2 and 3A) or 36 (Figs. 5 and 6), may
be enhanced by providing bevelled field-focusing core legs 57-
59 as illustrated in Fig. 10 and discussed hereinbefore
Although field-focusing core legs may also be employed
with the version of the spinner transducer with the shafts 12b
carrying projections 40 of magnetic material, the variation in
displacement of magnetic material relative to the core 50 as the
shaft rotates in that case is sufficiently distinct, and each
3 projection 40 overlaps the exciter coil 52 to enhance the
closing of the core 50 between the exciter coil and the,~
respective pickup coil 54 or 56, so that the amplitude modula-
tion of the pickup coil signals may be expected to be of
.: .
-21- ~3~3~9
sufficiently large signal-to-noise ratio without the use of
such focusing.
Since the shaft in each version of the spinner transducer
illustrated and described herein carries magnetic material
within the general vicinity of the sensor 14, and since the
varying electromagnetic field generated by the exciter coil 52
may be expected to transmit electromagnetic signals to the
pickup coils 54 and 56 even in the total absence of such
magnetic material carried by the shaft, a flux leakage may be
expected, which would tend to provide background signals always
present at the pickup coils 54 and 56. Consequently, the
electromagnetic signals available at the pickup coils 54 and 56
are sinusoidal carrier waves of non-~ero amplitudes, which are
modulated by the rotation of a magnetically-coded shaft to
produce pulses in the carrier wave amplitudes.
The amplitude modulated output signal of each of the
pickup coils 54 and 56 is of the same frequency as the sinu-
soidal wave impressed on the exciter coil 52 by the oscillator
62 and the driver 64. The specific frequency of the carrier
signal provided by the oscillator 62 is not critical, since the
information concerning the speed and rotational direction of
the shaft is carried by the amplitude modulations of the output
signals from the pickup coils 54 and 56, and not by the
frequency of the carrier signals so modulated. The pulse rate
of each modulated signal from a pickup coil will, at any moment,
be equal to the rotational frequency of the shaft multiplied by
the number of magnetic keys (grooves, edges, projections, etc.)
in the corresponding set of coding keys. For example, with a
constant shaft rotational speed and four projections 40 in a set
42 or 44 (Figs. 5 and 6), the resulting pulse rate of the
amplitude modulated pickup coil signal is four times the shaft
rotational frequency.
The amplitude modulated signals provided by the pickup
coils 54 and 56, which signals are designated as A and B,
respectively, in Figs. 11 and 12, are carried by appropriate
conductors 68 and 70, respectively, to the pulse counting
circuitry 16 illustrated in Fig. 12. The exciter coil input
signal C from the driver 64 is also carried to the pulse
counting circuitry 16 by appropriate conductors 72. Symbolic
representations of the three signals A, B and C are included in
the timing chart of Fig. 13, which illustrates relationships
among the signals, and their processed versions. Fig~ 13
illustrates the case of an upper set of magnetic coding along
a shaft, in any version, being offset by one quarter phase to
the right relative to the positioning of the lower coded set,
as viewed in any of the side elevations herein (Figs.12, 5 and
7) for example, and with the shaft rotating counterclockwise,
that is, from left to right as viewed in such elevations. Such
configuration and direction of rotation is consistent with the
fact that the pulses in signal A are illustrated in Fig. 13 as
leading the corresponding pulses of signal B by approximately
a 90 phase shift. The overlapping in time of corresponding
pulses in the signals A and s in Fig. 13 indicate that the coding
keys in the two coding sets carried by the shaft in question are
positioned to overlap in their respective rotational orienta-
tions on the shaft, as, for example, in the case of the grooved
version of Fig. 3 or the flats-and-edges version of Figs. 5 and
6. The particular pulse shapes included in signals A and B are
determined, at least in part, by the magnetic coding key
configurations as well as the rate of rotation of the shaft in
question.
Each of the signals A, B and C is initially processed in
a similar manner, and the signals are ultimately compared as
described hereinafter. For example, the output signal A from
the upper pickup coil 54 is received, by means of the conductors
68, by an amplifier and rectifier circuit 74, which amplifies
the signal and converts it to a pulsed dc signal. A filter
circuit 76 then limits the frequency of the carrier signal, and
integrates the signal to form a dc signal of square pulses,
designated Al and illustrated in Fig. 13. The voltage of the
squared pulse signal Al is then increased in an amplifier
circuit featuring a gain adjustment 78. Typically, an increase
of 200 may be utilized, while the gain adjustment may be used
to compensate for magnetic flux leakage that occurs at the
shaft. Similarly, the output signal B from the lower-pickup
coil 56 is converted to a dc signal of increased amplitude by
-23-
an amplifier and rectifier circuit 80, and then filtered and
integrated by the filter circuit 82 to produce a square pulsed
signal Bl, as illustrated in Fig. 13. The signal Bl is also
increased in voltage by an amplifier circuit featuring a gain
adjustment 84 to compensate for flux leakage. Fig. 13 is not
drawn to scale to the extent to allow a voltage comparison
between the representations of signals A, B, C and signals Al,
B1.
The driver circuit output signal C is also converted to a
dc signal of increased amplitude by an amplifier and rectifier
circuit 86. It should be noted that the carrier signal C is of
constant amplitude, so that when the dc version of the driver
signal is filtered and integrated by a filter circuit 88, a
constant amplitude dc signal Cl is produced, as illustrated in
Fig. 13. Subsequently, an amplifier circuit with gain adjust-
ment 90 increases the voltage level of the rectified/integrateddriver circuit signal and compensates for flux leakage as in the
previously described cases.
The output from the amplifier circuit 90 serves as a
reference voltage in two voltage comparators 92 and 94, which
receive the output signals from the pickup coil signal circuit
amplifiers 78 and 84, respectively. In each case, the differ-
ence between the reference voltage and the ampli~ied, squared
pickup coil pulse signal is determined, and where the differ-
ence is non-zero a square pulse is generated for the duration
of the measured non-zero value. Thus, the output from the
comparator circuit 92, which compares the processed signal from
the upper pickup coil 54 to the reference voltage, is a squared
pulse signal A2 as illustrated in Fig. 13. The corresponding
output signal from the comparator circuit 94, which compares
the reference voltage to the processed signal from the lower
pickup coil 58, is a squared pulse signal B2 as illustrated in
Fig. 13.
The difference between the reference voltage and each of
the processed pickup coil signals, as compared in the com-
parator circuits 92 and 94, respectively, reflects the varia-
tions in amplitude of the signals in the pickup coils 54-58,
compared to the driver signal C impressed on the exciter coil
~;~3l~ 9
-24-
52, due to the shunting of the core 50 by the magnetic keys on
the rotating shaft. The two signals A2 and B2 reflect the time
relationship between the initial pickup coil signals A and B,
but provide specific leading and trailing edges to allow an
S accurate determination of the direction of rotation of the
shaft, and to permit an accurate determination of the period of
the pulses in either signal A2 or B2 whereby the rate of
rotation of the shaft may be accurately determined. `The rate
of shaft rotation is determined by the number of square pulses
in either of the signals A2 or B2 in a given period of time,
divided by the number of magnetic coding keys in the corres-
ponding set of keys on the shaft. The direction of rotation of
the shaft, whether clockwise or counterclockwise, is deter-
mined by which of the two pulsed signals A2 or B2 leads the
lS other, as evidenced by the relative positions of the pulses of
the signals on the time chart shown in Fig. 13. Setting the
phase difference between the signals at 90 assists in this
determination. The overlapping of corresponding pulses in the
two signals A2 and B2, due to overlapping of corresponding
magnetic keys in the two encoded sets on the shaft, also
facilitates the determination of which signal leads the other.
The scaling of Fig. 13 does not allow comparison of the voltage
values of signals A2, B2 with signals A, B, C or Al, Bl.
The signals A2 and B2 may be compared in a speed and
direction determinator circuit 96, which may be of any con-
venient design. For example, a logic circuit may be utilized
for this purpose, readily receiving and processing the square
pulses of the signals A2 and B2. The output from the deter-
minator circuit 96 may be of any convenient form, containing
either a digital or analog signal with the speed of rotation
information in the form of time-coded pulses, for example, and
the direction of rotation information in the form of a positive-
or negative-going pulse, for example. The determinator circuit
output may be displayed by an appropriate readout circuit 98,
which may include one or more stripchart recorders, meters,
digital outputs, or the like. Details of the determinator and
readout circuits are not critical to the present invention.
A spinner transducer tool according to the present inven-
z~ ~ ~3~9
tion can be utilized in virtually any situation where speedand/or direction of rotation of a body, such as a shaft, is to
be determined. Particular details of such an application are
not essential to the understanding of the present invention.
However, one such application is considered herein for purposes
of illustration, and presentation of the present invention
within an e~vironment. The fluid flow measuring device 11
incorporating the spinner transducer tool 10 as shown in Figs.
lA-lE is of a type useful in oil well exploration and develop-
ment activities. The flow measuring device 11, which may be
employed with a variety of other well working tools (not shown)is positioned within a well and utilized to determine the rate
of flow of fluid, such as water and/or oil, along the well bore.
The flow measuring device 11 is generally elongate and
constructed with a fluid-tight outer casing assembly shown
generally at 100, which may be selectively opened toward the
bottom of the measuring device to receive fluid flowing up-
wardly along a well bore. The fluid flowing into the measuring
device activates the spinner transducer tool 10 (Fig. lD~
whereby flow rate and direction measurements are obtained, and
then exits the measuring device to continue along the borehole.
The casing 100 as well as various internal elements of the flow
measuring device 11 are constructed of multiple components,
mutually attached and fluid-sealed by appropriate seal mem-
bers, such as O-rings residing in annular grooves, as illus-
trated throughout Figs. lA-lD.
In Fig. lA, the top of the fluid flow measuring device 11
is illustrated as continuing downwardly from other equipment
(not shown) by which the flow measuring device may be positioned
within a well borehole. An electronics assembly 102 is posi-
tioned toward the top of the fluid flow measuring device 11, andincludes the exciter circuit 15 and possibly the pulse-counting
circuit 16, and also power supply apparatus to support such
down-hole circuitry. The electronics assembly 102 may be in
communication with equipment at the surface, such as the
readout equipment 9~ (Fig. 12) and control equipment (not
shown), by appropriate connectors (not shown) extending up-
wardly from the assembly 102~ A pair of set screws 104 may be
~ 3~ tl3
-26-
provided to maintain the electronics assembly 102 firmly inplace within the casing assembly 100.
A motor housing assembly 106 includes a motor 108 main-
tained fixed within the housing assembly by set screws 110 and
connected by appropriate conductors 112 to the electronics
assembly 102 which may also include appropriate power supply
components to operate the motor. The drive shaft of the motor
108 is joined by a connector assembly 114 to a switch lead screw
116, which features fine, small-pitch threads (Fig. lB). The
lower end of the screw 116 features an upset 118, which may ride
against a thrust bearing assembly 120 positioned between the
upset and the housing 106, and which upset is circumscribed by
a radial bearing assembly 122. The lead screw 116 is thus able
to rotate with the drive shaft of the motor 108, and is
prevented from exerting upward force against the motor by the
thrust bearings 120.
The switch lead screw upset end 118 resides within a drive
lead screw housing 124 and is connected to the top end of a drive
lead screw 126 by means of a tongue-in-groove connection shown
generally at 128. Thus, the drive lead screw 126 is rotatably
fixed relative to the switch lead screw 116, both lead screws
being selectively rotatable about their respective coinci-
dental longitudinal axes by operation of the motor 108. A
double-ring seal assembly shown generally at 130 rotatably
seals the drive lead screw 126 to the drive screw housing 124
at the top end of the drive screw. A bearing 132, held in place
by an appropriate bolt 134, supports the bottom end of the drive
lead screw 126 (Fig. lC). The bearing bolt 134 may be posi-
tioned through an access opening 136 in the drive screw housing
124; an additional access opening 138, which may be closed by
a threaded plug, is provided to access the top end of the drive
lead screw 126. An access opening 140 is provided in the motor
housing 106 at the location of the coupling 114.
Upper and lower limit switches 140 and 142, respectively,
are mounted in appropriate recesses in the side of the motor
assembly housing 106 toward opposite ends of the threaded
portion of the switch lead screw 116. Each limit switch 140 and
142 features a pair of bolt contactst extending through appro-
3~9
priate bores in the housing 106 to the interior passage 144
containing the switch lead screw 116, the bolt contacts in each
case being mutually displaced longitudinally along the passage
144. Each of the switches 140 and 142 is connected to the
electronics assembly 102 and/or the motor 108 by appropriate
conductors (not shown), and forms a part of the circuitry
controlling operation of the motor. A switch follower 146
threadedly engages the switch lead screw 116, and may be held
against rotation by an appropriate spline assembly or other
connection (not shown) with the lead screw housing 106, for
example. Thus, as the motor 108 rotates thè switch lead screw
116, the follower 146 moves longitudinally along the threads of
the lead screw, upwardly or downwardly depending on the direc-
tion of rotation of the screw. Contact of the follower 146 with
either of the limit switches 140 or 142 produces appropriate
switching in the motor control circuitry to automatically stop
rotation oE the motor 108 and, therfore, the two lead screws 116
and 126.
The lead screw housing 124 features an extended recess 148
within which resides coarse, large-pitch threads of the drive
lead screw 126 (Fig. lC). A sleeve assembly 150 generally
circumscribes the drive lead screw housing 124, extending
downwardly as further described hereinbelow. The sleeve as-
sembly 150 is coupled to the drive lead screw 126 by a follower
block 152, fixed to the sleeve assembly by a bolt 154 and
threadedly engaging the drive screw. The sleeve assembly 150
is otherwise longitudinally movable relative to the lead screw
housing 124. As the drive lead screw 126 is rotated, the
coupling therewith of the follower 152 results in longitudinal
movement of the sleeve assembly 150 relative to the drive lead
screw housing 124, upwardly or downwardly depending on the
direction of rotation of the drive screw. Since the threads of
the drive lead screw 126 and of the follower 152 are of large
pitch compared to the threads of the switch lead screw 116 and
the switch follower 116, the full extent of rotational movement
permitted by longitudinal movement of the switch follower 146
between the limit switches 140 and 142 is accompanied by the
greater longitudinal movement of the follower block 152 and the
3~
-28-
attached sleeve assembly 150 along the threaded portion of the
drive lead screw 126. Friction between the sleeve assembly 150
and the screw housing 124 as well as other components described
hereinafter prevents rotation of the sleeve assembly and the
follower block 152 with the drive screw 126 to cause longi-
tudinal movement of the sleeve assembly as the drive screw is
rotated. Alternatively, a spline-type connection could be
provided for this purpose.
An impeller housing 156 is mounted on the lower end of the
drive lead screw housing 124, and held fixed thereto by at least
one bolt 158 (Fig. lD). The upper portion of the impeller
housing 156 is generally tubular, containing a longitudinally-
extending passage 160. The impeller housing 156 continues
downwardly beyond its cylindrical portion in a multiplicity of
arms 162 which support a rod extension 164 ending in a cap, or
foot 166 (Fig. lE).
A plurality of flexible me~al strips 168 is mounted and
held by appropriate bolts 170, in a circumferential array about
the bottom of the cylindrical portion of the impeller housing
156. The bottom ends of the strips 168 are similarly mounted
on a generally tubular block 172 by bolts 174. The block 17~
circumscribes the rod 164 and is held against rotation relative
thereto by a pin 176 mounted in an appropriate bore through the
block and riding in a longitudinally-extending groove 178 in
the rod. A coil spring 180 is compressed between the bottom of
the block 172 and the top of the foot 166, and urges the block
upwardly relative to the rod 164. Such upward movement of the
block 172 tends to longitudinally compress the plurality of
strips 168, thereby flexing the strips radially outwardly into
the bowed configuration illustrated in Fig. 1~.
The upper halves of the strips 168 are connected by a
flexible cloth-like material 182 so that, in the bowed con-
figuration of the combinationofstrips 168 and material 182 as
illustrated in Fig. lE, a funnel or basket assembly is provided,
and is indicated generally at 184. Fluid flowing upwardly
relative to the basket 184 is directed thereby through the
openings between the arms 162 and into the passage 160 of the
impeller housing 156. The impeller housing 156 is equipped with
3~3~3
ports 185 which are aligned with ports 186 in the sleeve
assembly 150 when the sleeve assembly is in the upward con-
figuration illustrated. Fluid flowing into the bottom of the
passage 160 may thus emerge through the ports 185 and 186 to the
exterior of the flow measuring device 11.
Rotation of the drive lead screw 126 may be effected by
operation of the motor 108 to lower the follower block 152 and,
therefore, the sleeve assembly 150 relative to the d~ive screw
and the impeller housing 156. The bottom of the sleeve assembly
features a counterbore 150a which facilitates movement of the
sleeve assembly down over the extended strips 168. Such
enclosure of the strips 168 by the sleeve assembly 150 being
lowered relative thereto collapses the basket 184 inwardly
toward the rod 164. The collapse of the basket 184 forces the
block 172 downwardly, compressing the spring 180 against the
foot 156. The motor 108 may be operated until the switch
follower 146 reaches the lower limit switch 142, at which time
the sleeve assembly follower block 152 will be at the vicinity
of the bottom end of the threads of the drive lead screw 126.
At that point, the bottom of the sleeve assembly 150 will be
positioned essentially adjacent the block 172, fully enclosing
the basket 184 and minimizing any possible fluid flow into the
bottom of the passage 160 through the impeller housing 156.
The sleeve assembly ports 186 are longitudinally displaced from
the impeller housing ports 185 with the sleeve assembly 150 in
its lowered configuration enclosing the collapsed basket 184,
further inhibiting fluid movement through the passage 160.
In the closed-basket configuration with the sleeve as-
sembly 150 in its lower position, the flow measuring device 11
may be manipulated within a well with a minimum of resistance
to such motion, for example. When the flow measureing device
is positioned at the location at which flow measurements are to
be secured, the motor 108 may be operated to rotate the switch
lead screw 116 and the drive lead screw 126, raising the sleeve
assembly 150 until the switch follower 146 contacts the uppee
limit switch 140. At that point, the basket 184 will be
uncovered and extended by operation of the spring 180 as
illustrated in ~ig. lE, and the sleeve assembly ports 186 will
-- . U - ~3~
be aligned with the impeller housing ports 185 to permit fluid
flow outwardly from the casing assembly 100.
The impeller housing 156 contains an impeller assembly
shown generally at 187 in Fig. lO,and which comprises the shaft
12 of the spinner transducer tool 10 and one or more impeller
blades 188 arranged in spiral fashion on the shaft. It will be
appreciated that, while the spinner transducer tool embodiment
illustrated in Figs. 2 and 3 is also shown in Fig. lD, any
version of the spinner transducer tool previously described
herein may be utilized in the flow measuring device 11 as
illustrated in Figs. lA-lE. The shaft 12 is mounted between an
upper, fixed bearing 189 positioned within a counterbore in the
drive lead screw housing 124, and a lower, adjustable threaded
pin bearing 190, which is threadedly engaged in a mounting-frame
~5 192 held fixed by appropriate means within the passage 160 of
the impeller housing 156. A friction clamp 194 maintains the
pin bearing 190 in its selected position with its point against
the generally flat bottom of the shaft 12, while the pointed top
end of the shaft rides in a recess in the bottom of the upper
bearing 189. The bearing frame 192 includes multiple passages
196 for fluid flow along the impeller housing passage 160. The
impeller assembly 187 is thus free to rotate about its longi-
tudinal axis, riding on the upper and lower bearings 189 and
190, respectively. The spiral configuration of the impeller
blades 188 permits the passage of fluid flowing upwardly within
the impeller housing passage 160 and out through the aligned
ports 185 and 186 with such rotation about the shaft access.
It will be appreciated that the rate of rotation of the
shaft 12, caused by fluid flowing along the passage 160 and
impacting on the impeller blades 188, is directly proportional
to the rate of fluid flow along the passage. The direction of
rotation of the shaft 12 is also determined by the relative
direction of flow of the fluid in the passage 160 with respect
to the impeller assembly 185. While the spinner transducer tool
10, even as incorporated in the flow measuring device 11, may,
in general, detect the direction and rate of flow of fluid in
either longitudinal sense along a direction parallel to the
axis of the shaft 12, the flow measuring device illustrated in
-31- ~3~3~9
Fig. lA-lE is particularly designed to sense flow rate for fluid
moving upwardly relative to the device, having entered the
extended basket assembly 184, moving along the impeller housing
passage 160 and exiting the flow measuring device casing
assembly 100 through the aligned ports 185 and 186.
With fluid flowing upwardly through the passage 160 and by
the impeller assembly 187 as described, the sensor 14 detects
the passage of the magnetic keys on the shafts 12 a~ discussed
hereinbefore, and communicates the data signals to the elec-
tronic as~embly 102 for processing. The detector mechanism 14
is positioned within a recess l97 in the drive screw housing
124, and separated by the wall 60 from a longitudinal recess 198
which encompasses a portion of the shaft 12, including the
magnetic key sections 22 and 24. The bearing 189 is mounted in
a counterbore at the end of the recess 198.
The detector mechanism may be epoxied (not shown) in
position within the recess 197, or held in place by any
appropriate means. An extended passage 200 is provided along
the drive screw housing 124 from the recess 197 to the top of
the housing (Fig. lD) to accommodate appropriate conductors
(not included for purposes of clarity) communicating between
the detector mechanism and the electronic assembly 102. Suffi-
cient space accommodates such conductors along the annular
region between the motor housing assembly 106 and a casing
member 202, which circumscribes a large portion of the motor
housing assembly 106, being sealed thereto, and which is sealed
to the top of the drive lead screw housing 124 (Fig. lB). ~n
elongate port 204 permits the conductors to pass to the interior
of the motor housing assembly 106 above the motor assembly 108
for connection to the electronics assembly 102 (Fig. lA). The
conductor communication passage 200 may be constructed, in
part, by covering a trough, cut in the side of the drive lead
screw housing 124, by a strip 205, shown welded in place in Fig.
lC~
A pair of double-ring seal assemblies shown generally at
206 and at 208 seal the exterior of the drive lead screw housing
124 to the top of the impeller housing 156, the latter having
fluid flowing within its interior through the passage 160. As
-~2- ~ ~3~3~3
shown in Figs. lC and lD, the impeller housing passage communi-
cates through the recess 198, around the impeller bearing 189
(which is not sealed to the drive screw housing 124) and through
to the recess 148 by means of a narrow passage opening into the
recess containing the drive screw bearing 132. Fluid pressure
communication between the passage 160 and the recess 148 along
this interior path avoids pressure or vacuum locks in the
raising and lowering of the sleeve assembly 150.
Once the operation of measuring fl~id flow rate within a
well by use of the spinner transducer 10 as mounted within the
flow measuring device 11 of Figs. lA-lE is completed, the motor
may be selectively operated from the surface to lower the sleeve
assembly 150 over the basket assembly 184, rendering the flow
measuring device in its collapsed configuration as was uti-
lized for insertion and positioning within the well. The flow
measuring device 11 may then be further manipulated within the
well, or removed therefrom.
The spinner transducer tool, in any of its embodiments
described herein, provides an accurate tool for measuring speed
and direction of flow of fluid, for example. The use of
alternating magnetic fields and reliance on amplitude modu-
lation as opposed to frequency modulation of the data sisnal
enables reliable and accurate measurements to be made that are
impervious to vibration of the impeller shaft. Further, the
spinner transducer tool of the present invention includes
virtually no magnetic drag on the impeller shaft, due to the
fact that the magnetic fields involved are alternating, and
further provides accurate and reliable measurements for slow
rotational speed approaching zero rate of rotation. Also, the
high temperature rating of the ferrite core of the detector
mechanism 14 is particularly suitable for use in high tempera-
ture environments, such as may be encountered in wells. The
thin wall separation of the detector mechanism from the im-
peller shaft completely isolates the detector from the fluid-
filled environment in the shaft.
While the present invention has been shown in the environ-
ment of a fluid flow measuring device finding particular use in
wells, the spinner transducer tool is not limited to such
_33_ ~38~9
applicati ~ , but may rather be employ ~ in any operation which
, ~
requires the measurement of the speed and/or of rotation of a
shaft, whether caused by fluid flow or otherwise.
The foregoing disclosure and description of the invention
is illustrative and explanatory thereof, and various changes in
the size, shape and materials as well as in the details of the
illustrated construction may be made within the scope of the
appended claims without departing from the spirit of the
invention.
