U.S. patent application number 16/119578 was filed with the patent office on 2020-03-05 for adaptive pivot for variable displacement vane pump.
The applicant listed for this patent is GM GLOBAL TECHNOLOGY OPERATIONS LLC. Invention is credited to Bryan K. Pryor, Varoon Shankar, Chung Y. Wei.
Application Number | 20200072216 16/119578 |
Document ID | / |
Family ID | 69527491 |
Filed Date | 2020-03-05 |
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United States Patent
Application |
20200072216 |
Kind Code |
A1 |
Shankar; Varoon ; et
al. |
March 5, 2020 |
ADAPTIVE PIVOT FOR VARIABLE DISPLACEMENT VANE PUMP
Abstract
Variable displacement pumps and methods of pumping a fluid are
provided. An example pump may include a housing having an inlet and
an outlet, a rotor fixed for rotation with a shaft, the shaft
rotatably mounted within the housing, and a plurality of radially
extending vanes slidably disposed in the rotor. The pump may
further include a pivotable ring member defining at least in part a
control chamber about the rotor, wherein the ring member is
pivotable within the housing to vary an eccentricity of the ring
member with respect to the rotor. The ring member is configured to
shift a pivot position of the ring member from a first pivot
position to a second pivot position displaced from the first pivot
position.
Inventors: |
Shankar; Varoon; (Auburn
Hills, MI) ; Wei; Chung Y.; (Rochester Hills, MI)
; Pryor; Bryan K.; (Waterford, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM GLOBAL TECHNOLOGY OPERATIONS LLC |
DETROIT |
MI |
US |
|
|
Family ID: |
69527491 |
Appl. No.: |
16/119578 |
Filed: |
August 31, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 2/3442 20130101;
F04C 2240/80 20130101; F04C 14/226 20130101 |
International
Class: |
F04C 14/22 20060101
F04C014/22; F04C 2/344 20060101 F04C002/344 |
Claims
1. A variable displacement pump, comprising: a housing having an
inlet and an outlet; a rotor fixed for rotation with a shaft, the
shaft rotatably mounted within the housing; a plurality of radially
extending vanes slidably disposed in the rotor; and a pivotable
ring member defining at least in part a control chamber about the
rotor, wherein the ring member is pivotable within the housing to
vary an eccentricity of the ring member with respect to the rotor,
wherein the ring member is configured to shift a pivot position of
the ring member from a first pivot position to a second pivot
position displaced from the first pivot position.
2. The pump of claim 1, further comprising a resilient element
engaged with the ring member, thereby biasing the ring member in a
first pivot direction opposed to a second pivot direction, the
control chamber positioned such that an external pressure
introduced into the control chamber applies a force to the ring
member tending to pivot the ring member in the second pivot
direction.
3. The pump of claim 1, wherein the radially extending vanes define
one or more vane chambers configured to develop pressure during
operation of the pump, the pressure in the one or more vane
chambers imparting a force to the ring member offset from a pivot
pin of the ring member by an offset distance, wherein the pivot
position is shiftable to reduce the offset distance.
4. The pump of claim 1, further comprising a pivot pin configured
to define the first and second pivot positions.
5. The pump of claim 4, further comprising a pivot anchor fixed to
the ring member.
6. The pump of claim 1, wherein the housing defines at least first
and second undulations corresponding to the first and second pivot
positions of the ring member, respectively.
7. The pump of claim 1, further comprising a cam rotatably fixed
within the housing.
8. The pump of claim 7, wherein the cam defines the first pivot
position of the ring member when placed in a first rotational
position, and the cam defines the second pivot position of the ring
member when rotated from the first rotational position to a second
rotational position.
9. A variable displacement pump, comprising: a housing having an
inlet and an outlet; a rotor fixed for rotation with a shaft, the
shaft rotatably mounted within the housing; a plurality of radially
extending vanes slidably disposed in the rotor; a pivotable ring
member defining at least in part a control chamber about the rotor,
wherein the ring member is pivotable within the housing to vary an
eccentricity of the ring member with respect to the rotor, wherein
the ring member is configured to shift a pivot position of the ring
member from a first pivot position to a second pivot position
displaced from the first pivot position; and a resilient element
engaged with the ring member, thereby biasing the ring member in a
first pivot direction about the first and second pivot
positions.
10. The pump of claim 9, wherein the radially extending vanes
define one or more vane chambers configured to develop pressure
during operation of the pump, the pressure in the one or more vane
chambers imparting a force to the ring member offset from a pivot
pin of the ring member by an offset distance, wherein the pivot
position is shiftable to reduce the offset distance.
11. The pump of claim 9, further comprising a pivot pin configured
to define the first and second pivot positions.
12. The pump of claim 9, wherein the housing defines first and
second undulations corresponding to the first and second pivot
positions of the ring member, respectively.
13. The pump of claim 9, further comprising a cam rotatably fixed
within the housing.
14. A method of pumping a fluid, comprising: providing a housing
having an inlet and an outlet; rotatably mounting a rotor within
the housing upon a shaft; positioning a plurality of radially
extending vanes in the rotor, the vanes each slidably disposed in
the rotor; defining a control chamber about the rotor with a
pivotable ring member, wherein the ring member is pivotable within
the housing to vary an eccentricity of the ring member with respect
to the rotor; and shifting a pivot position of the ring member from
a first pivot position to a second pivot position displaced from
the first pivot position.
15. The method of claim 14, further comprising biasing the ring
member in a first pivot direction by engaging the ring member with
a resilient element.
16. The method of claim 14, wherein the radially extending vanes
define one or more vane chambers configured to develop pressure
during operation of the pump, the pressure in the one or more vane
chambers imparting a force to the ring member offset from a pivot
pin of the ring member by an offset distance; and wherein shifting
the pivot position reduces the offset distance.
17. The method of claim 16, wherein the offset is eliminated by the
reduction in the offset distance.
18. The method of claim 14, wherein shifting the pivot position
includes shifting a pivot pin within the housing.
19. The method of claim 14, further comprising providing first and
second undulations in the housing corresponding to the first and
second pivot positions of the ring member, respectively.
20. The method of claim 14, further comprising providing a cam
rotatably fixed within the housing, wherein the pivot position is
shifted by rotating the cam.
Description
INTRODUCTION
[0001] Variable displacement oil pumps may employ a pivotable ring
member or slide within a housing, which facilitates a change in
pump displacement by way of varying an eccentricity of the slide
with respect to a pump rotor. The pivotable slide may be biased in
a given direction about the axis of the rotor with a spring. The
slide may be secured within the housing at a fixed pivot point, and
pivoted to a desired position corresponding to a desired
displacement of the pump.
[0002] The ring member position is typically controlled in part by
the biasing of the spring, and application of an external pressure
against the spring. Internal pressure may also build within the
ring member as rotor speed increases. As rotor speed becomes
significant, internal torque placed upon the ring member and other
components builds may become similarly significant, far outweighing
the available external pressure that can be applied to the ring
member. Accordingly, known variable displacement pumps may lose a
degree of control of displacement as the internal torque becomes
large. This is especially disadvantageous when eccentricity of the
ring member (and, thus, pump displacement) is relatively large or
close to a maximum of the pump.
[0003] Accordingly, there is a need for an improved pump that
addresses the above shortcomings.
SUMMARY
[0004] In at least some example approaches, a variable displacement
pump is provided that includes a housing having an inlet and an
outlet, a rotor fixed for rotation with a shaft, the shaft
rotatably mounted within the housing, and a plurality of radially
extending vanes slidably disposed in the rotor. The pump may
further include a pivotable ring member defining at least in part a
control chamber about the rotor, wherein the ring member is
pivotable within the housing to vary an eccentricity of the ring
member with respect to the rotor. The ring member is configured to
shift a pivot position of the ring member from a first pivot
position to a second pivot position displaced from the first pivot
position.
[0005] In some examples, a resilient element may be engaged with
the ring member, thereby biasing the ring member in a first pivot
direction opposed to a second pivot direction, the control chamber
positioned such that an external pressure introduced into the
control chamber applies a force to the ring member tending to pivot
the ring member in the second pivot direction.
[0006] In some example approaches, the radially extending vanes
define one or more vane chambers configured to develop pressure
during operation of the pump, the pressure in the one or more vane
chambers imparting a force to the ring member offset from a pivot
pin of the ring member by an offset distance, wherein the pivot
position is shiftable to reduce the offset distance.
[0007] In some examples, the pump includes a pivot pin configured
to define the first and second pivot positions. Some of these
examples may include a pivot anchor fixed to the ring member.
[0008] The housing may, in some examples, define at least first and
second undulations corresponding to the first and second pivot
positions of the ring member, respectively.
[0009] In other examples, the pump may include a cam rotatably
fixed within the housing. In some of these examples, the cam
defines the first pivot position of the ring member when placed in
a first rotational position, and the cam defines the second pivot
position of the ring member when rotated from the first rotational
position to a second rotational position.
[0010] Another example variable displacement pump, includes a
housing having an inlet and an outlet, a rotor fixed for rotation
with a shaft, the shaft rotatably mounted within the housing, and a
plurality of radially extending vanes slidably disposed in the
rotor. THE pump may include a pivotable ring member defining at
least in part a control chamber about the rotor, wherein the ring
member is pivotable within the housing to vary an eccentricity of
the ring member with respect to the rotor. The ring member is
configured to shift a pivot position of the ring member from a
first pivot position to a second pivot position displaced from the
first pivot position. The pump may further include a resilient
element engaged with the ring member, thereby biasing the ring
member in a first pivot direction about the first and second pivot
positions.
[0011] In some of these examples, the radially extending vanes
define one or more vane chambers configured to develop pressure
during operation of the pump, the pressure in the one or more vane
chambers imparting a force to the ring member offset from a pivot
pin of the ring member by an offset distance, wherein the pivot
position is shiftable to reduce the offset distance.
[0012] Some examples pumps may further include a pivot pin
configured to define the first and second pivot positions.
[0013] In some example approaches, the housing defines first and
second undulations corresponding to the first and second pivot
positions of the ring member, respectively.
[0014] In other examples, the pump may include a cam rotatably
fixed within the housing.
[0015] In at least some examples, a method of pumping a fluid
includes providing a housing having an inlet and an outlet,
rotatably mounting a rotor within the housing upon a shaft,
positioning a plurality of radially extending vanes in the rotor,
the vanes each slidably disposed in the rotor, and defining a
control chamber about the rotor with a pivotable ring member,
wherein the ring member is pivotable within the housing to vary an
eccentricity of the ring member with respect to the rotor. The
method may further include shifting a pivot position of the ring
member from a first pivot position to a second pivot position
displaced from the first pivot position.
[0016] In some example methods, the ring member is biased in a
first pivot direction by engaging the ring member with a resilient
element.
[0017] In some of the example methods, the radially extending vanes
define one or more vane chambers configured to develop pressure
during operation of the pump, the pressure in the one or more vane
chambers imparting a force to the ring member offset from a pivot
pin of the ring member by an offset distance. In these examples,
the shifting of the pivot position may reduce the offset distance.
In at least a subset of these examples, the offset is eliminated by
the reduction in the offset distance.
[0018] In some example methods, shifting the pivot position
includes shifting a pivot pin within the housing.
[0019] In at least some examples, a method includes providing first
and second undulations in the housing corresponding to the first
and second pivot positions of the ring member, respectively.
[0020] In other example methods, a cam may be rotatably fixed
within the housing, wherein the pivot position is shifted by
rotating the cam.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] One or more embodiments of the invention will hereinafter be
described in conjunction with the appended drawings, wherein like
designations denote like elements, and wherein:
[0022] FIG. 1 is a partial cutaway view of a variable displacement
oil pump having a ring element with a movable pivot;
[0023] FIG. 2A is an example movable pivot for the variable
displacement pump of FIG. 1;
[0024] FIG. 2B is another example of a movable pivot for the
variable displacement pump of FIG. 1;
[0025] FIG. 2C is an illustration of a free-body diagram of the
ring member of the pump of FIG. 1, illustrating internal torque and
other forces applied to the ring member during operation of the
pump;
[0026] FIG. 3A is a graph illustrating changes in internal torque
of the variable displacement pump of FIG. 1 in response to shifts
in a ring element pivot point using the movable pivots of FIG. 2A
or 2B, according to an example illustration;
[0027] FIG. 3B is a graph illustrating changes in internal torque
of the variable displacement pump of FIG. 1 in response to shifts
in a ring element pivot point using the movable pivots of FIG. 2A
or 2B, according to another example; and
[0028] FIG. 4 is an example process flow diagram, illustrating
example methods for operating a variable displacement pump.
DETAILED DESCRIPTION
[0029] Turning now to FIG. 1, an example variable displacement pump
100 is illustrated. The pump 100 may include a housing 102 having
an inlet and an outlet (not shown in FIG. 1A). The pump 100 may
further include a rotor 104 that is fixed for rotation with a shaft
106. The shaft 106 may be rotatably mounted within the housing 102.
The housing 102 may be an intermediate housing of an assembly
forming a housing for the pump 100. A plurality of radially
extending vanes 107 may be slidably disposed in the rotor 104. A
pivotable ring member 108 defines a vane chamber 110 about the
rotor 104. The ring member 108 may be pivotable within the housing
102, facilitating the varying of displacement output by way of
altering an eccentricity of the ring member 108 with respect to the
rotor 104.
[0030] The pump 100 also includes a biasing assembly 112. The
biasing assembly 112 may apply a biasing force to the ring member
108 urging a lever 128 of the ring member 108 generally upward (in
the orientation of FIG. 1), thereby tending to urge the ring member
108 to pivot in a first direction about a pivot pin 109 (as
illustrated in FIG. 1, generally upwards). The biasing assembly 112
may include at least one resilient element 114 extending
longitudinally. The resilient element, in one example, may be a
coil spring formed of steel or aluminum, merely as examples.
[0031] The biasing assembly 112 may generally be used to control
displacement of the pump 100 by way of positioning the ring member
108, along with other forces applied selectively to the ring member
108. More specifically, as seen in FIG. 1A, the ring element 108
may be eccentric with respect to the rotor 104. The ring member 108
is pivotable about a pivot pin 109. The pivot pin 109 may be
provided by any mechanism that is convenient, as will be discussed
further below. A plurality of vanes 107 are radially slidable in
the rotor 107. A vane ring 105 may control the radial position of
the vanes 107 within the rotor 104. Each of the vanes 107 contact
the ring member 108 at a radially outermost end of the vane 107,
and as such the ring member 108 generally controls the radial
position of each of the vanes 107 with respect to the rotor 104.
When the rotor 104 turns during operation, pressure builds within
the vane chamber 110 of the pump 100 that is defined at least in
part by the adjacent vanes 107, the rotor 104, and the ring member
108. Pressure builds within the chamber 110 as the rotor 104 turns,
due to the volume restriction placed upon the chamber 110 by the
ring member 108. The internal pressure that builds within the
chamber 110 applies a torque to the ring member 108. More
specifically, pressure building within the chamber 110 may apply a
force to the ring member 108, due to an offset of the resultant
force of the vane chamber(s) 110 from the pivot pin 109, as will be
discussed further below. Thus, torque placed upon the ring member
108 by the pressure in the vane chamber(s) 110 may be in opposition
to the force applied to the ring member 108 by the biasing assembly
112.
[0032] The position of the ring member 108 may be varied by
application of an external force via a pressure within a control
chamber 111. Thus, external pressure applied to the ring member by
the control chamber 111 may act in opposition to the biasing force
applied by the biasing assembly 112. The control chamber 111 may be
defined at least in part by the housing 102 and the ring member
108. A slide seal 115 of the ring member 108 may facilitate buildup
of pressure within the control chamber 111 by generally sealing
between the ring member 108 and housing 102 as the ring member 108
pivots about the pivot pin 109, with the slide seal 115 sliding
along the housing 102. The control chamber 111 may receive
pressure, for example, from a return line (not shown) of an engine
associated with the pump 100. When the ring member 108 is rotated
to a position where it is concentric with respect to the rotor 104,
the output of the pump 100 is zero displacement, as there is no
difference in volume between the control chamber 110 and an exit
port of the pump 100. By contrast, output displacement of the pump
100 is generally maximized when the ring member 108 is positioned
at its greatest degree of eccentricity with respect to the rotor
104. As the external pressure applied to the ring member 108 may be
controlled independently of the speed of the rotor 104, the
external pressure may be modified during operation to position the
ring member 108 (in opposition to the torque applied by the biasing
assembly 112 and/or the internal pressure of the control chamber
110) to obtain a desired displacement output.
[0033] In the example illustrated in FIG. 1, an internal support
surface 126 may provide a reaction surface for a first end of the
resilient element 114 of the biasing assembly 112 (i.e., the end of
the coil spring nearest surface 126) within the housing 102. A
second end of the resilient element of the biasing assembly 112
opposite the first end may contact a lever 128 of the ring member
108. The lever 128 is generally fixed with the ring member 108 (and
may be formed as a unitary part with the ring member 108) and
extends radially away from the ring member 108. As such, the end of
coil spring 114 contacting lever 128 may provide compression force
from the coil spring 114. The biasing assembly 112 may thereby
generally apply a biasing force to the ring member 108 in the first
direction D.
[0034] As shown in FIG. 1, the pivot pin 109 of the ring member 108
may be fixed to the ring member 108, and may be movable in a first
"x" direction as illustrated. The pivot pin 109 may also be movable
in a second "y" direction that is perpendicular to the "x"
direction. The position of the pivot pin 109 may be shifted in the
x and/or y directions to reduce or eliminate an offset of the pivot
pin 109 from the resultant force placed upon the ring member 108 by
the vane chamber(s) 110 during operation, as will be discussed
further below. Accordingly, the ring member 108 may pivot about
different locations of the pivot pin 109. When the ring member 108
is pivoted about the pivot pin 109, the lever 128 may shift upward
and downward generally, e.g., in a similar direction as the "x"
direction.
[0035] As will be described further below, by shifting the pivot
pin 109 the amount of an internal torque imparted to the ring
member 108 by the forces created by the buildup of pressure within
the vane chamber(s) 110 may be modified. For example, by shifting
the pivot pin 109, an offset between the force imparted
collectively upon the ring element 108 by the pressure within the
vane chamber(s) 110 and the pivot pin 109 may be reduced or
eliminated. Typically, shifting the pivot in the "x" direction as
shown in FIG. 1 may have a larger impact in comparison to shifts of
the pivot pin 109 in the "y" direction as shown in FIG. 1. Changes
in the internal hydraulic torque may also be more significant than
the change in spring torque during operation, and therefore can be
used to regulate the pump pressure.
[0036] Shifting the pivot pin 109 may also adjust lever arms
associated with forces applied to the ring member 108 by the
resilient element 114. For example, shifting the pivot pin 109 in
the "y" direction and away from the lever 128 (i.e., pivot pin 109
moves to the right in FIG. 1) may increase a distance of a lever
arm formed by the lever 128 with respect to the pivot pin 109,
thereby increasing the moment imparted by the resilient element 114
(which is generally in compression) upon the ring element 108 and
increasing the degree to which the resilient element 114 may resist
internal torque. Similarly, a moment imparted to the ring member
108 by external force applied by the control chamber 111 to the
ring member 108 may generally be increased by shifting the pivot
pin 109 further away from the lever 128 (i.e., pivot pin 109 moves
to the right in FIG. 1). On the other hand, shifting the pivot pin
109 in the opposite direction (i.e., to the left and/or upward in
FIG. 1) may generally have the opposite effect, as it would reduce
the torque or moment imparted to the ring member 108 by a force
placed upon the ring member 108 by pressure of the control chamber
111 or the resilient element 114. The lever 128 may have a
resilient slide 140 or other laterally extendable member configured
to allow limited lateral movement of the lever 128 when the pivot
pin 109 is shifted laterally, i.e., in the y direction.
[0037] Shifting the pivot pin 109 in the "x" direction may, as
noted above, alter an offset of the pivot pin 109 with respect to
resultant forces placed upon the ring member 108 by pressure
building within one or more of the vane chamber(s) 110. Thus, as
the offset is reduced, any torque imparted to the ring member 108
by the force of the pressure within the vane chamber(s) 110 may be
reduced. Similarly, where offset is increased, the torque imparted
to the ring member 108 by the force of the pressure within the vane
chamber(s) 110 may be increased.
[0038] Turning now to FIGS. 2A and 2B, example mechanisms for
shifting the pivot pin 109 are described in further detail. Both of
the example mechanisms include a pivot anchor 109a or 109b, which
may be secured to the pivot pin 109 adjacent the ring member 108.
Alternatively, the example pivot anchors 109a, 109b may be formed
as a single piece with the ring member 108.
[0039] In the example of FIG. 2A, a first example of a pivot anchor
109a includes a profiled anchor surface 200a that is mated with a
corresponding housing surface 202a. The profiled anchor surface
200a and housing surface 202a may be shaped with different radii,
such that the pivot pin 109 travels along a path P1 when the pivot
anchor 109a "rocks" with respect to the housing 102. As the pivot
anchor 109a rocks with respect to the housing 102, the pivot pin
109 moves in both "x" and "y" directions, thereby altering an
offset of the pivot pin 109 with respect to forces placed upon the
ring member 108 by pressure within the vane chamber(s) 110, and/or
varying a lever arm of the forces discussed above that are placed
upon the ring member 108 by the resilient element 114 and/or the
control chamber 111. The pivot anchor 109a and housing 102 may have
corresponding gear teeth or other undulations to keep the pivot
anchor 109a and housing 102 engaged. For example, as illustrated in
FIG. 2A, corresponding teeth 204a and 204b of the anchor surface
200a and housing surface 202a, respectively, are engaged when the
lever 128 (not shown in FIG. 2A) of the ring member 108 is pivoted
toward an upper end of the housing 102. By contrast, corresponding
second teeth 206a and 206b of the anchor surface 200a and housing
surface 202a, respectively, are engaged when the lever 128 (not
shown in FIG. 2A) of the ring member 108 is pivoted in the opposite
direction, i.e., toward a lower end of the housing 102. The pivot
anchor 109a and housing 102 may have, alternatively or in addition
to the corresponding teeth/undulations, a high-friction material
along the contacting surfaces of the pivot anchor 109a and housing
102.
[0040] Turning now to FIG. 2B, another example pivot anchor 109b is
illustrated. The pivot anchor 109b is fixed to the pivot pin 109,
which extends from a rear face of the ring member 108 in similar
fashion as described above with respect to pivot anchor 109a. The
pivot anchor 109b, however, interfaces with a rotatable cam 210
along an anchor surface 208. The rotatable cam 210 is fixed
translationally within the housing 102 and is rotatable with
respect to the housing 102. Upon rotation of the cam 210, the pivot
anchor 109a translates along the path P.sub.2, thereby shifting
vertically (i.e., in the "x" direction) and laterally (i.e., in the
"y" direction), thereby also shifting the ring member 108 (shown in
phantom in FIG. 2B). As with the pivot anchor 109a, when the pivot
anchor 109b moves via rotation of the cam 210 with respect to the
housing 102, the pivot pin 109 moves in both "x" and "y"
directions, thereby varying a lever arm of the forces placed upon
the ring member 108, and/or altering an offset of the pivot pin 109
with respect to forces placed upon the ring member 108 by pressure
within the vane chamber(s) 110 to cause a reduction in the internal
torque. The cam 210 may be rotated by any mechanism that is
convenient. Merely as examples, the cam 210 may be rotated by a
hydraulic pressure or mechanism, or an electric solenoid.
[0041] Referring now to FIG. 2C, the forces applied to the ring
member 108 during operation may include a spring force F.sub.S
imparted by the resilient element 114, external pressure applied by
the control chamber 111, which creates an external force F.sub.0 in
opposition to the spring force F.sub.S, and an internal force
F.sub.i that is created by the buildup of pressure within the
chambers 110 defined within the ring member 108. The internal force
F.sub.i, due to the offset O with respect to the pivot pin 109,
creates an internal torque .tau..sub.I acting upon the ring member
108, which acts in opposition to the spring force F.sub.S. By
shifting the pivot pin 109 in the x and/or y directions, the pivot
pin 109 of the ring element 108 may be shifted closer to a position
where it is coincident with the resolved force F.sub.i caused by
the internal pressure of the vane chamber(s) 110, thereby reducing
the internal torque .tau..sub.I placed upon the ring member 108
caused by the force F.sub.i. In other words, the closer the pivot
position is to the line defined by the force F.sub.i, the less the
internal torque .tau..sub.I upon the ring member 108 resulting from
the force F.sub.i. Additionally, shifting of the pivot pin 109 may
also alter lever arm(s) of (1) the force F.sub.O imparted by the
control chamber 111 and (2) the spring force F.sub.S with respect
to the pivot pin 109, thereby reducing/increasing the torque
imparted upon the ring member 108 by those forces.
[0042] In the example pump 100 described above in FIGS. 1, 2A, and
2B, an eccentricity of the ring member 108 with respect to the
rotor 104 may be varied independent of the rotating speed of the
rotor 104. By comparison, in previous approaches a displacement of
the pump 100 would become "self-regulated" by the pump at elevated
speeds of the rotor 104. More specifically, at relatively high
rotor 104 speeds, the internal pressure generated by the rotor 104
upon the ring member 108 (i.e., from the vane chamber(s) 110)
becomes relatively large in comparison to the force of the
resilient element 114 and/or the maximum pressure applied by the
control chamber 111. Accordingly, the ring member 108 under such
previous approaches cannot as easily be shifted to a desired
position, particularly at elevated rotor 104 speeds. In fact, at
extremely high pump speeds, the torque generated by the internal
pressure on the ring element or slide in these previous approaches
can overcome a maximum force applied by the control chamber,
preventing control of ring element position.
[0043] By contrast, the example pump 100 described above allows the
reduction of internal torque caused by the pressure within the ring
member 108 by shifting the pivot pin 109. Internal torque of the
ring member 108, i.e., that caused by the buildup of pressure
within the chamber 110 during operation, may also be affected by
rotor 104 speed, viscosity of oil being pumped through the pump
100, and displacement of the pump 100. With the reduced torque
placed upon the ring member 108 when the pivot pin 109 is shifted,
the eccentricity of the ring member 108 with respect to the rotor
104 may be more easily controlled by the external pressure applied
via the control chamber 111. In one example, the internal torque
generated by the chamber 110 upon the ring member 108 may be less
than that imparted by the resilient element 114. With the increased
control of displacement made possible in part by the reduced
internal torque facilitated by the shiftable pivot pin 109,
alternative control devices such as an oil control valve (OCV) may
have greater effect, and in some cases may not be needed at all. In
other words, in such examples lacking an oil control valve, the
control chamber 111 may exclusively control position of the ring
member 108, in opposition to the spring force F.sub.S, due to the
reduced effect (i.e., torque) of the internal forces F.sub.i.
[0044] The increased control offered by exemplary pumps such as
pump 100 described above is illustrated in the graphs illustrated
in FIGS. 3A-3B. In each of FIGS. 3A and 3B, an internal torque
caused by the force F.sub.i is illustrated as a function of
movement of the pivot pin 109 along the x and y directions,
consistent with the orientations of x and y directions with respect
to the pivot pin 109 illustrated in FIGS. 1, 2A, and 2B. The
example pivot anchors 109a, 109b may facilitate a shifting of the
pivot pin 109, allowing increased control of the displacement
output of the pump 100. In a first example of a pump 100
illustrated in FIG. 3A, the internal torque acting upon ring member
108 that is caused by the internal force F.sub.i may be varied from
1.4 Newton-meters (N-m) to 51 N-m by shifting the pivot pin 109 4.0
millimeters in either direction along the "x" axis from a baseline
("zero") position, and 1.0 millimeters in either direction along
the "y" axis from the baseline position. A second example of a pump
100 is illustrated in FIG. 3B, in which the internal torque acting
upon ring member 108 that is caused by the internal force F.sub.i
may be varied from 2.3 Newton-meters (N-m) to 7.4 N-m by shifting
the pivot pin 109 4.0 millimeters in either direction along the "x"
axis from a baseline ("zero") position, and 1.0 millimeters in
either direction along the "y" axis from the baseline position.
[0045] Turning now to FIG. 4, an example process 400 of pumping a
fluid, e.g., with a variable displacement pump, is described.
Process 400 may being at block 410, where a housing may be
provided. For example, as described above, a housing 102 may have
an inlet and outlet for drawings in and expelling a fluid, e.g.,
oil. Process 400 may then proceed to block 420.
[0046] At block 420, a rotor may be rotatably mounted within the
housing upon a shaft. In one example described above, rotor 104 may
be mounted upon a shaft 106 for rotation within the housing
102.
[0047] Proceeding to block 430, a plurality of radially extending
vanes may be positioned in the rotor. As described above, in some
examples, vanes 107 may be provided, each of which are slidably
disposed in the rotor 104 such that they may define a varying
volume of each chamber 110 about the circumference of the rotor
104. Process 400 may then proceed to block 440.
[0048] At block 440, a control chamber may be defined about the
rotor with a pivotable ring member. In an example as described
above, a ring member 108 is provided, which is pivotable within the
housing 102 to vary an eccentricity of the ring member 108 with
respect to the rotor 104. Accordingly, varying amounts of
displacement of the pump 100 may be provided, depending on the
amount of eccentricity of the ring member 108 with respect to the
rotor 104.
[0049] Proceeding to block 450, the ring member may be biased in a
first pivot direction. For example, as described above the ring
member 108 may be biased about the rotor in a first direction by
way of a biasing assembly 112. In some example approaches, a
biasing assembly 112 includes a resilient element 114, e.g., a coil
spring. In some examples, the direction in which the biasing
assembly 112 biases the ring element 108 is opposite to the
direction in which pressure from the control chamber 111 urges the
ring element 108. Process 400 may then proceed to block 460.
[0050] At block 460, a pivot position of the ring member may be
shifted from a first pivot position to a second pivot position
displaced from the first pivot position. In some example approaches
consistent with those illustrated above, a ring member 108 may
pivot about a pivot pin 109, which is shifted within the housing
102 to effect a corresponding shift in the axis of rotation of the
ring member 108. The pivot position may be changed to reduce or
increase a lever arm with respect to forces applied by the
resilient element 114 and/or the control chamber 111, and/or reduce
or increase an offset of the pivot pin 109 from a resultant force
created by pressure within the vane chamber(s) 110. In another
example, the pivot position may be shifted radially with respect to
the rotor 104. A shift of the pivot pin 109 within the housing 102
may thus alter a moment or amount of torque imparted to the ring
member 108 during operation. Accordingly, internal torque upon the
ring member 108 may be reduced (or increased, if desired).
[0051] In some examples, the housing 102 may define a varying
surface profile, e.g., with a plurality of teeth 204b, 206b, e.g.,
as illustrated above in FIG. 2A, or other undulations. In these
examples, this "rockered" profile shifts the pivot pin 109 when the
ring member 108 is rotated.
[0052] In other examples, a rotatable cam 210 may facilitate
shifting a pivot position of the ring member 108 independently of
the ring member 108 position about the rotor 104, such as in the
example of FIG. 2B. In other words, in contrast to the rockered
profile illustrated in FIG. 2A, which depends upon pivoting of the
ring member 108 to shift the pivot position, the cam 210 may be
rotated independently of the ring member 108 position. Merely as
examples, the cam 210 may be rotated by hydraulic pressure or
electrically actuated, e.g., via a solenoid.
[0053] It is to be understood that the foregoing is a description
of one or more embodiments of the invention. The invention is not
limited to the particular embodiment(s) disclosed herein, but
rather is defined solely by the claims below. Furthermore, the
statements contained in the foregoing description relate to
particular embodiments and are not to be construed as limitations
on the scope of the invention or on the definition of terms used in
the claims, except where a term or phrase is expressly defined
above. Various other embodiments and various changes and
modifications to the disclosed embodiment(s) will become apparent
to those skilled in the art. All such other embodiments, changes,
and modifications are intended to come within the scope of the
appended claims.
[0054] As used in this specification and claims, the terms "e.g.,"
"for example," "for instance," "such as," and "like," and the verbs
"comprising," "having," "including," and their other verb forms,
when used in conjunction with a listing of one or more components
or other items, are each to be construed as open-ended, meaning
that the listing is not to be considered as excluding other,
additional components or items. Other terms are to be construed
using their broadest reasonable meaning unless they are used in a
context that requires a different interpretation.
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