U.S. patent application number 16/160319 was filed with the patent office on 2019-04-18 for rotatable piston assembly.
This patent application is currently assigned to CurAegis Technologies, Inc.. The applicant listed for this patent is CurAegis Technologies, Inc.. Invention is credited to Douglas A. Hemink.
Application Number | 20190112926 16/160319 |
Document ID | / |
Family ID | 64051834 |
Filed Date | 2019-04-18 |
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United States Patent
Application |
20190112926 |
Kind Code |
A1 |
Hemink; Douglas A. |
April 18, 2019 |
ROTATABLE PISTON ASSEMBLY
Abstract
A rotatable piston assembly for a reciprocating piston type
hydraulic machine includes a rotatable piston configured for a
controlled rotation and configured to reciprocate within a cylinder
bore of the reciprocating piston type hydraulic machine.
Inventors: |
Hemink; Douglas A.;
(Churchville, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CurAegis Technologies, Inc. |
Rochester |
NY |
US |
|
|
Assignee: |
CurAegis Technologies, Inc.
Rochester
NY
|
Family ID: |
64051834 |
Appl. No.: |
16/160319 |
Filed: |
October 15, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62572635 |
Oct 16, 2017 |
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62671693 |
May 15, 2018 |
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62671690 |
May 15, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 1/146 20130101;
F04B 2201/0201 20130101; F16H 1/28 20130101; F01B 3/0085 20130101;
F04B 1/128 20130101; F04B 1/295 20130101; F01B 3/0079 20130101;
F03C 1/0686 20130101; F04B 1/14 20130101; F04B 1/182 20130101; F04B
1/126 20130101; F04B 2201/0807 20130101; F04B 7/06 20130101; F03C
1/061 20130101; F04B 1/16 20130101; F01B 3/101 20130101; F04B 1/29
20130101; F03C 1/0613 20130101; F04B 1/30 20130101; F01B 3/02
20130101; F04B 1/124 20130101; F04B 1/20 20130101; F04B 53/18
20130101 |
International
Class: |
F01B 3/00 20060101
F01B003/00; F01B 3/02 20060101 F01B003/02; F01B 3/10 20060101
F01B003/10 |
Claims
1. A rotatable piston assembly for a reciprocating piston type
hydraulic machine, the rotatable piston assembly comprising: a
rotatable piston configured for a controlled rotation and
configured to reciprocate within a cylinder bore of the
reciprocating piston type hydraulic machine along a cylinder bore
axis of the cylinder bore, wherein the reciprocating piston type
hydraulic machine is an axial piston machine comprising a rotating
swash mechanism configured for variable displacement, a stationary
cylinder block, and a rotatable shaft coupled to the rotating swash
mechanism, and the rotating swash mechanism is a rotating wobble
plate connected to a swash collar through a plurality of bearings,
and the swash collar is connected to the rotatable shaft through a
plurality of bearings.
2. The rotatable piston assembly of claim 1, wherein the axial
piston machine comprises: a manifold disposed within the stationary
cylinder block and a swash housing configured to house a double
sided piston configuration, the manifold configured for fluid
communication with the rotatable piston assembly, the manifold
comprising: a proximal manifold port disposed at a proximal end of
the manifold within the stationary cylinder block; a proximal
manifold passage in fluid communication with the proximal manifold
port and comprising a plurality of proximal manifold passage port
openings; a distal manifold port disposed along a distal end of the
manifold within the stationary cylinder block; a distal manifold
passage in fluid communication with the distal manifold port and
comprising a plurality of distal manifold passage port openings; a
proximal inward cylinder block port disposed in the stationary
cylinder block and in fluid communication with one of the plurality
of proximal manifold passage port openings; a proximal outward
cylinder block port in fluid communication with an outward proximal
manifold passage port opening; a distal inward cylinder block port
disposed in the stationary cylinder block and in fluid
communication with one of the plurality of distal manifold passage
port openings; and a distal outward cylinder block port in fluid
communication with an outward distal manifold passage port
opening.
3. The rotatable piston assembly of claim 2, wherein the rotating
wobble plate comprises a pair of opposed plate bearing surfaces,
the rotatable piston comprises a double sided configuration and an
intermediate piston constrained joint interface disposed between
ends of the rotatable piston, the rotatable piston assembly
comprising: a slipper assembly configured to couple with and
constrain rotation of the rotatable piston about the intermediate
piston constrained joint interface, the slipper assembly
comprising: a slipper shoe comprising a proximal interface and a
distal interface configured to be disposed between the pair of
opposed plate bearing surfaces of the rotating wobble plate, the
rotatable piston configured for a controlled rotation with respect
to the rotating wobble plate and a slipper pin configured to couple
the slipper shoe to the rotatable piston at the intermediate piston
constrained joint interface.
4. The rotatable piston assembly of claim 3, further comprising a
plurality of pistons, a plurality of slipper assemblies, and a
plurality of proximal and distal outward cylinder block ports, each
slipper assembly coupled to a respective piston, wherein a first
end of each piston aligns with the proximal inward cylinder block
port in fluid communication with one of the plurality of proximal
manifold passage port openings of the proximal manifold passage or
aligns with the proximal outward cylinder block port in fluid
communication with the outward proximal manifold passage port
opening as the rotatable piston rotates, a second end of each
piston aligns with the distal inward cylinder block port in fluid
communication with one of the plurality of distal manifold passage
port openings of the distal manifold passage or aligns with the
distal outward cylinder block port in fluid communication with the
outward distal manifold passage port opening as the rotatable
piston rotates, and when the first end of each piston aligns with
one of the proximal inward cylinder block port or the proximal
outward cylinder block port, the second end of each piston
respectively aligns with one other of the distal outward cylinder
block port or the distal inward cylinder block port as the
rotatable piston rotates.
5. The rotatable piston assembly of claim 1, the axial piston
machine comprising a plurality of housing fluid passages configured
for control by an externally coupled flow control device, a
plurality of shaft fluid passages configured to be in fluid
communication with at least one of the plurality of housing fluid
passages, and a control piston chamber configured to be in fluid
communication with the plurality of shaft fluid passages for
receipt of pressured control fluid.
6. The rotatable piston assembly of claim 5, the axial piston
machine comprising a control piston and a bias spring disposed
within the swash collar and configured to adjust a tilt angle of
the rotating wobble plate with respect to an axis of the rotatable
shaft.
7. The rotatable piston assembly of claim 6, wherein the control
piston and the bias spring are supported by the rotatable shaft and
coupled to the swash collar, the bias spring is configured to tilt
the swash collar with respect the rotatable shaft, and the control
piston is configured to cooperate with the control piston chamber
and reciprocate within a bore defining the control piston chamber
such that the control piston and the bias spring are configured to
adjust the tilt angle of the rotating wobble plate with respect to
the axis of the rotatable shaft based on a received amount of
pressurized control fluid.
8. The rotatable piston assembly of claim 1, wherein the axial
piston machine comprises a plurality of bearing components between
an interface of the swash collar and the rotatable shaft.
9. The rotatable piston assembly of claim 8, wherein the plurality
of bearing components comprise a plurality of hydrostatic pressure
pockets included at the interface of the swash collar and the
rotatable shaft.
10. The rotatable piston assembly of claim 9, wherein each
hydrostatic pressure pocket is defined within an interior wall
surface of the swash collar facing an exterior wall surface of the
rotatable shaft.
11. The rotatable piston assembly of claim 10, wherein a seal
component is disposed between the exterior wall surface of the
rotatable shaft and the interior wall surface of the swash collar
defining each respective hydrostatic pressure pocket to provide a
seal about the hydrostatic pressure pocket.
12. The rotatable piston assembly of claim 1, wherein each
rotatable piston comprises a first integral valve port at a first
end.
13. The rotatable piston assembly of claim 12, wherein each
rotatable piston comprises a second integral valve port at a second
end opposing the first end.
14. The rotatable piston assembly of claim 13, wherein the first
integral valve port is circumferentially disposed with respect to
the second integral valve port.
15. The rotatable piston assembly of claim 14, wherein the first
integral valve port is circumferentially disposed at 180 degrees
with respect to the second integral valve port.
16. A method for using an axial piston machine as at least one of a
pump and a motor, the axial piston machine including a rotating
swash mechanism configured for variable displacement, a stationary
cylinder block, and a rotatable shaft coupled to the rotating swash
mechanism, the method comprising: reciprocating a rotatable piston
of a rotatable piston assembly including a double sided piston
configuration in a cylinder bore of the stationary cylinder block
of the axial piston machine; rotating the rotatable piston in the
cylinder bore during reciprocation; and controlling rotation of the
rotatable piston in the cylinder bore through a rotational control
assembly, wherein rotation of the rotating swash mechanism is
configured to rotate the rotational control assembly.
17. The method of claim 16, wherein the rotatable piston comprises
a first integral valve port at a first end and a second integral
valve port at a second end that is circumferentially disposed with
respect to the first end, and the first integral valve port and the
second integral valve port are configured to provide a passage for
fluid flow in one of a pump direction and a motor direction
opposite the pump direction to respectively act as one of the pump
and the motor.
18. The method of claim 16, wherein the rotational control assembly
comprises a slipper assembly configured to couple with the
rotatable piston at an intermediate piston constrained joint
interface with a slipper pin and to constrain rotation of the
rotatable piston about the intermediate piston constrained joint
interface.
19. The method of claim 16, further comprising: adjusting a tilt
angle of the rotating swash mechanism comprising a rotating wobble
plate with respect to an axis of the rotatable shaft through
positioning of a control piston and a bias spring disposed within a
swash collar coupling the rotatable shaft to the rotating wobble
plate and based on an amount of pressured control fluid received in
a control piston chamber.
20. The method of claim 19, wherein the control piston is
configured to cooperate with the control piston chamber and
reciprocate within a bore defining the control piston chamber, the
control piston chamber in fluid communication with a plurality of
shaft fluid passages that are in fluid communication with a
plurality of housing fluid passages configured for control by an
externally coupled flow control device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present disclosure claims priority to U.S. Provisional
Patent Application No. 62/572,635, with attorney docket no. TVC
0143 MA, filed Oct. 16, 2017, and entitled "ROTATABLE PISTON VALVE
ASSEMBLY," U.S. Provisional Patent Application No. 62/671,693, with
attorney docket no. TVC 0143 M2, filed May 15, 2018, and entitled
"ROTATABLE PISTON WITH VALVE ASSEMBLY," and U.S. Provisional Patent
Application No. 62/671,690, with attorney docket no. TVC 0145 MA,
filed May 15, 2018, and entitled "VARIABLE DISPLACEMENT PISTON
MACHINE," the entireties of which are incorporated by reference
herein.
TECHNICAL FIELD
[0002] The present disclosure relates to a reciprocating piston
type hydraulic machine, and more specifically to a rotatable piston
assembly of such a hydraulic machine.
BACKGROUND
[0003] Displacement machines may be used to transform mechanical
energy into hydraulic energy and the reverse. Fixed and variable
displacement reciprocating piston (or plunger) type machine may
include radial, bent-axis, and axial machines. An axial piston
machine may include (1) first type including a rotating swashplate
and a stationary cylinder block or (2) a second type including a
stationary swashplate and rotating cylinder block. The first type
of axial piston machine including the rotating swashplate may
include increased unbalanced forces on a shaft and the swashplate,
requiring additional bearings to absorb such forces than the second
type of axial piston machine including the rotating cylinder block.
The rotating cylinder block can, by contrast, absorb such
unbalanced forces but requires an additional housing component and
tends to have a large rotational mass inertia resulting in high
power loss.
[0004] Accordingly, a need exists for alternative components and
machine types to increase efficiency, packaging, and operation of
such displacement machines.
BRIEF SUMMARY
[0005] According to the subject matter of the present disclosure, a
rotatable piston assembly for a reciprocating piston type hydraulic
machine may include a rotatable piston configured for a controlled
rotation and configured to reciprocate within a cylinder bore of
the reciprocating piston type hydraulic machine along a cylinder
bore axis of the cylinder bore, wherein the reciprocating piston
type hydraulic machine is an axial piston machine comprising a
rotating swash mechanism configured for variable displacement, a
stationary cylinder block, and a rotatable shaft coupled to the
rotating swash mechanism, and the rotating swash mechanism is a
rotating wobble plate connected to a swash collar through a
plurality of bearings, and the swash collar is connected to the
rotatable shaft through a plurality of bearings.
[0006] In accordance with one other embodiment of the present
disclosure, a method for using an axial piston machine as at least
one of a pump and a motor, the axial piston machine including a
rotating swash mechanism configured for variable displacement, a
stationary cylinder block, and a rotatable shaft coupled to the
rotating swash mechanism may include reciprocating a rotatable
piston of a rotatable piston assembly including a double sided
piston configuration in a cylinder bore of the stationary cylinder
block of the axial piston machine, rotating the rotatable piston in
the cylinder bore during reciprocation, and controlling rotation of
the rotatable piston in the cylinder bore through a rotational
control assembly, wherein rotation of the rotating swash mechanism
is configured to rotate the rotational control assembly.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0007] The following detailed description of specific embodiments
of the present disclosure can be best understood when read in
conjunction with the following drawings, where like structure is
indicated with like reference numerals and in which:
[0008] FIG. 1 illustrates a perspective view of an axial piston
device including a rotating swashplate, a stationary cylinder
block, and a rotatable piston assembly, according to one or more
embodiments as shown and described herein;
[0009] FIG. 2 illustrates a cross-sectional view of a first half
portion and interior components of a second half portion of the
axial piston device of FIG. 1;
[0010] FIG. 3 illustrates a top plane view of the axial piston
device of FIG. 1;
[0011] FIG. 4 illustrates a perspective and partially
cross-sectional side view of the axial piston device of FIG. 1;
[0012] FIG. 5 illustrates a cross-sectional side view of the axial
piston device of FIG. 1;
[0013] FIG. 6 illustrates a perspective view of select interior
components of the axial piston device of FIG. 1, including a
rotatable piston valve assembly according to one or more
embodiments as shown and described herein;
[0014] FIG. 7 illustrates a perspective view of the rotatable
piston valve assembly of FIG. 6;
[0015] FIG. 8A illustrates a cross-sectional view of an outward
position of a rotatable piston valve assembly of FIG. 7 in the
axial piston device of FIG. 1 such that an integral piston valve of
the rotatable piston valve assembly is aligned with a manifold
outlet port of the axial piston device, according to one or more
embodiments as shown and described herein;
[0016] FIG. 8B illustrates a cross-sectional view of a forward
intermediate position of the rotatable piston valve assembly of
FIG. 7 in the axial piston device of FIG. 1 such that the integral
piston valve of the rotatable piston valve assembly is positioned
to face a first direction between and aligned with neither the
manifold outlet port nor a manifold inlet port of the axial piston
device, according to one or more embodiments as shown and described
herein;
[0017] FIG. 8C illustrates a cross-sectional view of an inward
position of the rotatable piston valve assembly of FIG. 7 in the
axial piston device of FIG. 1 such that the integral piston valve
of the rotatable piston valve assembly is aligned with the manifold
inlet port of the axial piston device, according to one or more
embodiments as shown and described herein;
[0018] FIG. 8D illustrates a cross-sectional view of an
intermediate rearward position of the rotatable piston valve
assembly of FIG. 7 in the axial piston device of FIG. 1 such that
the integral piston valve of the rotatable piston valve assembly is
positioned to face a second direction, opposite the first direction
of FIG. 8B, between and aligned with neither the manifold outlet
port nor the manifold inlet port of the axial piston device,
according to one or more embodiments as shown and described
herein;
[0019] FIG. 9A illustrates a perspective view of a first position
of the rotatable piston valve assembly of FIG. 7 in the outward
position of FIG. 8A;
[0020] FIG. 9B illustrates a perspective view of a second position
of the rotatable piston valve assembly of FIG. 7 in between the
outward position of FIG. 8A and the forward intermediate position
of FIG. 8B;
[0021] FIG. 9C illustrates a perspective view of a third position
of the rotatable piston valve assembly of FIG. 7 in the forward
intermediate position of FIG. 8B;
[0022] FIG. 9D illustrates a perspective view of a fourth position
of the rotatable piston valve assembly of FIG. 7 in between the
forward intermediate position of FIG. 8B and the inward position of
FIG. 8C;
[0023] FIG. 9E illustrates a perspective view of a fifth position
of the rotatable piston valve assembly of FIG. 7 in the inward
position of FIG. 8C;
[0024] FIG. 9F illustrates a perspective view of a sixth position
of the rotatable piston valve assembly of FIG. 7 in between the
inward position of FIG. 8C and the intermediate rearward position
of FIG. 8D;
[0025] FIG. 9G illustrates a perspective view of a seventh position
of the rotatable piston valve assembly of FIG. 7 in the
intermediate rearward position of FIG. 8D;
[0026] FIG. 9H illustrates a perspective view of a eighth position
of the rotatable piston valve assembly of FIG. 7 in between the
intermediate rearward position of FIG. 8D and the outward position
of FIG. 8A;
[0027] FIG. 10 illustrates a cross-sectional side view of an axial
piston device with a fixed, tilted displacement assembly forwardly
tilted with respective to a pin axis perpendicular to a
longitudinal shaft axis of a shaft to depict a forward to backward
tilt view, according to one or more embodiments as shown and
described herein;
[0028] FIG. 11 illustrates a cross-sectional side view of the axial
piston device of FIG. 10 with the tilted displacement assembly
rotated about 90 degrees clockwise to depict a side-to-side tilt
view, according to one or more embodiments as shown and described
herein;
[0029] FIG. 12 illustrates a perspective view of a rotatable piston
with valve assembly of the axial piston device of FIG. 10,
according to one or more embodiments as shown and described
herein;
[0030] FIG. 13 illustrates a perspective view of the tilted
displacement assembly of the axial piston device of FIG. 10
including a plurality of rotatable piston with valve assemblies,
according to one or more embodiments as shown and described
herein;
[0031] FIG. 14 illustrates a cross-sectional side view of an axial
piston device with a tilted variable displacement assembly tilted
with respective to a pin axis perpendicular to a longitudinal shaft
axis of a shaft, according to one or more embodiments as shown and
described herein;
[0032] FIG. 15 illustrates a cross-sectional side view of the axial
piston device of FIG. 14 with the variable displacement assembly
generally parallel and not tilted with respect to the pin axis and
perpendicular to the longitudinal shaft axis of the shaft;
[0033] FIG. 16 illustrates another cross-sectional side view of the
axial piston device of FIG. 14;
[0034] FIG. 17 illustrates a perspective view of a shaft and collar
assembly of the variable displacement assembly of the axial piston
device of FIG. 14;
[0035] FIG. 18 illustrates a perspective view of the variable
displacement assembly of the axial piston device of FIG. 14;
[0036] FIG. 19 illustrates a side view of the shaft of the axial
piston device of FIG. 14;
[0037] FIG. 20 illustrates a perspective, partially cross-sectional
side view of the axial piston device of FIG. 14 with a plurality of
pistons in a first position;
[0038] FIG. 21 illustrates the axial piston device of FIG. 20
rotated counter-clockwise such that the plurality of pistons are in
a second position;
[0039] FIG. 22 illustrates the axial piston device of FIG. 21
further rotated counter-clockwise such that the plurality of
pistons are in a third position;
[0040] FIG. 23 illustrates another perspective, partially
cross-sectional side view of the axial piston device of FIG. 14 in
a first position;
[0041] FIG. 24 illustrates the axial piston device of FIG. 23
rotated clockwise to a second position that is similar to the third
position shown in FIG. 22;
[0042] FIG. 25 illustrates the axial piston device of FIG. 24
rotated clockwise to a third position that is similar to the
position shown in FIG. 14;
[0043] FIG. 26 illustrates an alternative perspective view of the
axial piston device of FIG. 21 in the second position along with an
effective piston force;
[0044] FIG. 27 illustrates a schematic cross-sectional side view of
the axial piston device of FIG. 14 including moments and forces
acting upon the axial piston device during operation;
[0045] FIG. 28 illustrates a perspective view of an axial piston
device including a gear drive assembly embodiment configured to
control piston rotation, the pistons including integral valves,
according to one or more embodiments as shown and described
herein;
[0046] FIG. 29 illustrates a cross-sectional view of the axial
piston device of FIG. 28;
[0047] FIG. 30 illustrates an opposing side perspective view of the
axial piston device of FIG. 28 in an embodiment not illustrating an
integral valve;
[0048] FIG. 31 illustrates a side cross-sectional view of an axial
piston device including another gear drive assembly embodiment
configured to control piston rotation, the pistons including
integral valves, according to one or more embodiments as shown and
described herein;
[0049] FIG. 32 illustrates a cross-sectional side view of an axial
piston device including an integrated dual port manifold assembly
for communication with at least a dual port rotatable piston,
according to one or more embodiments as shown and described
herein;
[0050] FIG. 33 illustrates a cross-sectional side view of the axial
piston device of FIG. 32 further illustrating the integrated dual
port manifold assembly in communication with at least a pair of
opposingly situated dual port rotatable pistons;
[0051] FIG. 34 illustrates a cross-sectional side view of a single
sided rotatable piston with hydrostatic pockets, according to one
or more embodiments as shown and described herein;
[0052] FIG. 35 illustrates a perspective view of the single sided
rotatable piston of FIG. 34;
[0053] FIG. 36 illustrates a cross-sectional side view of a double
sided rotatable piston with hydrostatic pockets, according to one
or more embodiments as shown and described herein;
[0054] FIG. 37 illustrates a perspective view of the double sided
rotatable piston of FIG. 36;
[0055] FIG. 38 illustrates forces acting upon the single sided
rotatable piston of FIGS. 34-35;
[0056] FIG. 39 illustrates forces acting about the double sided
rotatable piston of FIGS. 36-37;
[0057] FIG. 40 illustrates an axial piston device including a fixed
angle rotatable piston, according to one or more embodiments as
shown and described herein;
[0058] FIG. 41 illustrates an enlarged view of the fixed angle
rotatable piston of FIG. 40;
[0059] FIG. 42 illustrates an exploded view of a piston-slipper
revolute joint including a three-piece assembly having a press fit
trunnion, according to one or more embodiments as shown and
described herein; and
[0060] FIG. 43 illustrates a cross-sectional view of a
piston-slipper revolute joint including a constrained spherical
joint, according to one or more embodiments as shown and described
herein.
DETAILED DESCRIPTION
[0061] Rotating swash mechanism type axial piston machines may be
used with a check-valve as a one-way valve to operate at extreme
pressures with a relatively low rotating mass. However, use of such
machines with such a one-way valve are limited to pump applications
with a flow in a first direction and do not work as a motor using a
flow in a second direction opposite the first direction as the
check-valve only allows for fluid flow in one direction. Further, a
rotating swash mechanism type axial piston machine, including a
stationary cylinder block, tends to include increase unbalanced
forces on a shaft and the swash mechanism, requiring additional
bearings to absorb such forces than another type of axial piston
machine including the rotating cylinder block and a stationary
swash mechanism. A rotating swash mechanism type axial piston
machine with a stationary cylinder block including a mechanically
phased rotary valve, rather than a check-valve, to provide for use
of the rotating swash mechanism type axial piston machine as a pump
and motor and assist with absorbing unbalanced forces is described
in U.S. Pat. App. No. 2016/0348672, entitled "Axial Piston Device,"
filed Feb. 5, 2015, which is incorporated by reference in its
entirety herein.
[0062] The rotating cylinder block piston machine with the
stationary swash mechanism and phased valve, in contrast to a
stationary cylinder block piston machine with a rotating swash
mechanism and one-way check-valve, also allows for operation as
both a pump and motor. In such a rotating cylinder block piston
machine, the distribution of low and high pressure from inlet and
outlet, to the piston chamber volume, is controlled by an angular
rotation of a piston about a shaft axis of rotation with respect to
the swash mechanism and valve plate. The phased valve in such a
machine may include two openings that are opposed about a midplane,
which is substantially parallel to a swash mechanism pivot plate,
to thus provide a mechanical means to control a connecting and
disconnecting of the displacement chamber from the inlet and outlet
during a compression and decompression stroke of the piston as the
piston translates in and out of a cylinder bore due to the piston
position about the inclined swash mechanism. The rotating cylinder
block of such a piston machine is able to absorb unbalanced forces
yet requires an additional housing component and tends to have a
large rotational mass inertia resulting in high power loss.
[0063] The present disclosure at least with respect to FIGS. 1-9H
describes a rotatable piston assembly including a rotary piston
that has an integral valve and is configured for a controlled
rotation for use with displacement machines, such as a rotating
swash mechanism type axial piston machine with a stationary
cylinder block or a rotating cylinder block piston machine with a
stationary swash mechanism. In embodiments, the swash mechanism may
be a swashplate. The rotary valve piston is able to absorb
unbalanced forces while further allowing for use of the rotating
swashplate type axial piston machine as a pump and motor. While the
disclosure herein describes use of such a rotary valve with a
rotating swashplate type axial piston machine, it is within the
scope of this disclosure that the rotary valve piston described
herein may be used with all fixed and variable displacement
reciprocating piston type machines.
[0064] The present disclosure at least with respect to FIGS. 1-9H
further describes an embodiment of a rotatable piston assembly
including a plurality of rotatable pistons that are joined to a
respective plurality of slipper assemblies through a constrained
fit, such as a revolute joint interface. Such a constrained fit
constrains and controls rotation of each piston with respect to
each slipper assembly with respect to a single axis of rotation. As
a rotatable shaft rotates about a shaft axis of rotation, a
connected rotating swashplate also rotates. The rotation of the
swashplate in turn rotates the plurality of slipper assemblies.
These assemblies interface, as described in greater detail below,
with the rotating swashplate. The rotation of the plurality of
slipper assemblies effects a corresponding rotation of the
plurality of rotatable pistons such that the plurality of rotatable
pistons respectively rotate about bore axes of rotation of each
cylinder bore within which each rotatable piston is positioned. The
result is that the pistons rotate in a controlled fashion within
respective bores through interaction between the slipper assemblies
and the swashplate such that the rotation of the pistons
corresponds with the rotation of the swashplate and a synchronized
rotation of the rotatable shaft. Further, in embodiments in which
the rotatable piston assembly includes a rotatable valve assembly
having a valve disposed within and integral to the piston, the
valve within the piston is periodically opened and closed with
respect to one or more ports defined in each cylinder bore by
rotation of the piston.
[0065] Referring initially to FIG. 1, an axial piston machine 100
including a rotating swashplate 40, stationary cylinder block 10,
and a rotatable piston assembly 88 including a plurality of pistons
60. Referring to FIGS. 1-3 and 7, the rotatable piston assembly 88
may include a rotatable piston valve assembly 90 (FIGS. 2 and 7)
including the plurality of pistons 60 and integrated valves within
the respective pistons 60. As a non-limiting example, referring to
FIGS. 2-3, each piston 60 has an integral valve port 602. Use of a
rotatable piston 60 including an integral valve port 602 eliminates
a need for a separate valve component to operate with the rotatable
piston 60, resulting in a less expensive and lighter assembly, and
allowing for control of an inlet and outlet of fluid in a
bi-directional flow as described herein. However, use of a
rotatable piston assembly 88 for a controlled rotation as described
herein of the plurality of pistons 60 not including an integral
valve such as the integral valve port 602 but rather including a
separate valve component is contemplated within the scope of this
disclosure.
[0066] Referring to FIGS. 1-2, the axial piston machine 100
includes a rotatable shaft 30 coupled to the rotating swashplate 40
such that rotation of one of the rotatable shaft 30 and rotating
swashplate 40 effects a rotation of the other of the rotatable
shaft 30 and rotating swashplate 40. The axial piston machine 100
further includes a plurality of slipper assemblies 50, which are
described in greater detail below, that include distal interfaces
501 (FIGS. 4-5 and 7) seated against a proximal interface 401
(FIGS. 4-5) of the rotating swashplate 40. Additionally, the axial
piston machine 100 includes a swash housing 20 coupled to the
stationary cylinder block 10. The swash housing 20 includes at
least a drain port 201, a distal manifold port 202 of a manifold
110, and a proximal manifold port 106 of the manifold 110, each of
which will be described in greater detail further below.
[0067] In embodiments, and referring to FIGS. 4-7, the rotatable
piston valve assembly 90 of the axial piston machine 100 may
include a hold down assembly 704 including a hold down plate 70
configured to interface with each slipper assembly 50 and apply a
force to maintain each slipper assembly 50 against the rotating
swashplate 40. The hold down plate 70 may be forced into contact
with each slipper assembly 50 by a spring-loaded pivot ball of the
hold down assembly 704 (FIG. 6). The spring-loaded pivot ball may
be a pivot bearing 80 that provides a hold down force while
permitting the hold down plate 70 to pivot and rotate freely about
the pivot bearing 80. Thus, hold down forces from the hold down
plate 70 against each slipper assembly 50 are assisted through a
plurality of springs 907 that force the pivot bearing 80 (FIG. 6)
against the hold down plate 70 through a pivot interface 801 (FIG.
5) of the pivot bearing 80 and an interfacing pivot interface 702
of the hold down plate 70. Eventually, the forces from the
plurality of springs 907 disposed about a respective plurality of
pins 906 extending from the pivot bearing 80 and into the
stationary cylinder block 10 are transferred to each slipper
assembly 50 through planar joints formed by a hold down planar
interface 701 (FIG. 5) of the hold down plate 70 interacting
against a corresponding hold down interface 503 of each slipper
assembly 50. A slipper neck interface 703 of the hold down plate 70
additionally interacts with and against a slipper neck 504 of the
slipper assembly 50.
[0068] Referring to FIG. 5, a large bearing 901 is disposed around
a distal end of the rotating swashplate 40, and a small bearing 902
is disposed about a proximal end of the rotatable shaft 30.
Further, a shaft seal 903 is disposed about an intermediate portion
of the rotatable shaft 30 distal to the large bearing 901 and
within a distal end of the swash housing 20. A retaining ring 908
is distally disposed below the shaft seal 903 and spaced about the
rotatable shaft 30. Another retaining ring 909 is disposed about a
portion of the rotatable shaft 30 distal to the pivot bearing 80
and against a central, proximal portion of the rotating swashplate
40. A static seal 905 and a static seal 904 are disposed between
joining portions of the stationary cylinder block 10 and the swash
housing 20 near and past opposing ends of a distal manifold passage
105, as described in greater detail below.
[0069] Referring to FIGS. 1-7, in embodiments, the rotatable piston
assembly 88 for a reciprocating piston type hydraulic machine
includes at least a rotatable piston 60 configured for a controlled
rotation and configured to reciprocate within a cylinder bore 101
(FIG. 5) of the reciprocating piston type hydraulic machine via a
cylinder bore interface 601 (FIG. 4). The reciprocating piston type
hydraulic machine may be the axial piston machine 100 that includes
the rotating swashplate 40 configured for rotation and the
stationary cylinder block 10. Rotation of the rotatable shaft 30 is
configured to rotate the rotating swashplate 40, and rotation of
the rotating swashplate 40 is configured to control a rotation of
the rotatable piston 60 during reciprocation of the rotatable
piston 60 in the cylinder bore 101, as described in greater detail
further below.
[0070] In embodiments in which the rotatable piston assembly 88
includes the rotatable piston valve assembly 90, the rotatable
piston 60 includes a valve passage 603 (FIGS. 5-7) including an
opening disposed at a proximal end of the rotatable piston 60. The
rotatable piston 60 further includes the integral valve port 602
that is in fluid communication with the valve passage 603. The
integral valve port 602 is configured to provide a passage for
fluid flow in one of a first direction and a second direction
opposite the first direction to respectively act as one of a pump
and a motor.
[0071] Referring to FIGS. 5 and 7, in an embodiment, each piston 60
includes a piston revolute joint interface 604 disposed at a distal
end of the rotatable piston 60. The rotatable piston assembly 88
further includes a slipper assembly 50 for each piston 60. Rotation
of the rotating swashplate 40 is configured to control a rotation
of the rotatable piston 60 through a slipper assembly 50. The
revolute joint interface 604 is shaped with a planar pair of
opposing ends and a cylindrical center portion between the planar
pair of opposing ends.
[0072] The slipper assembly 50 includes a slipper shoe 507
including the distal interface 501 configured to be disposed
against the proximal interface 401 of a swashplate, such as the
rotating swashplate 40. Each piston 60 is configured for a
controlled rotation with respect to the rotating swashplate 40
through the seated connection of each respective slipper assembly
50. The slipper assembly 50 further includes a slipper neck 504,
proximally extending from the slipper shoe 507, and a slipper
revolute joint. While the slipper revolute joint is described
herein to provide a controlled rotation of the rotatable piston 60
with respect to the slipper assembly 50, it is contemplated within
the scope of this disclosure that other joints and/or structures to
provide such a controlled rotation between the rotatable piston 60
and the slipper assembly 50 are within the scope of this
disclosure.
[0073] The slipper joint includes a slipper revolute joint
interface 502 configured to be received by the piston revolute
joint interface 604 disposed at a distal end of the rotatable
piston 60 such that translation of the slipper assembly 50 results
in a corresponding translation of the respectively joined rotatable
piston 60. The slipper revolute joint interface 502 includes a
central portion defined by a pair of opposing central side walls
defining an opening sized to receive the cylindrical center portion
of the revolute joint interface 604 of the rotatable piston 60. The
pair of opposing central side walls further define at opposite ends
a U-shape opening, each U-shaped opening sized and shaped to
correspond with a shape of a respective one of the planar pair of
opposing ends of the revolute joint interface 604 of the rotatable
piston 60. Thus, each rotatable piston 60 is able to pivot about a
horizontal axis of rotation defined through and between the planar
pair of opposing ends of the revolute joint interface 604 of the
rotatable piston 60 when each rotatable piston 60 is disposed
within a respective slipper revolute joint interface 502 but is
constrained from pivoting about any other axis with respect to the
planar pair of opposing ends. Further, rotation of each slipper
assembly 50 will cause a corresponding rotation of the rotatable
piston 60.
[0074] In embodiments, the slipper assembly 50 further comprises a
slipper ring 911 (FIG. 5) configured to be disposed around the
slipper neck 504 to maintain a fit between the piston revolute
joint interface 604 and the slipper revolute joint interface 502
and provide an axial constraint to prevent movement of the
rotatable piston 60 and the slipper assembly 50 relative to one
another along a revolute joint interface axis. In embodiments, a
retaining ring 910 may be disposed about a proximal end of the
slipper ring 911 to retain the slipper ring 911 against the slipper
assembly 50.
[0075] The connection between the slipper revolute joint interface
502 and the piston revolute joint interface 604 allows for a
restriction of rotation freedom between the respective slipper
assembly 50 and piston 60 such that a rotation of the respective
slipper assembly 50 effects a corresponding rotation of the
rotatable piston 60, and the rotatable piston 60 is not free to
rotate with respect to the respective slipper assembly 50
independent of rotation of the respective slipper assembly 50. This
is in contrast to, for example, a ball and socket spherical joint
between a slipper assembly and a piston. While such a spherical
joint would provide a translational constraint between the piston
and the slipper assembly, rotational freedom about all axes would
be permitted by the spherical joint such that the piston would be
free to rotate within the spherical joint in multiple degrees of
freedom independent of movement of a respectively joined slipper
assembly. With the spherical joint, the piston is radially
constrained by a cylinder bore 101 and fluid film therebetween,
allowing for the piston to rotate and translate about a transverse
axis where the transverse position of the piston is located by an
inclined surface of the swashplate with respect to the piston. With
the spherical joint, the piston-slipper assembly is rotationally
constrained about the piston traverse axis by friction alone
between a slipper-to-swashplate interface, a slipper-to-piston
interface, and a piston-to-cylinder bore interface and the only
resistance is friction. Friction forces of these three interfaces
continuously compete to define a rotational orientation of the
piston-slipper assembly having the spherical joint.
[0076] By contrast, the revolute joint between a joined rotatable
piston 60 and slipper assembly 50 described herein provides a
translation constraint therebetween and additionally restricts
rotational freedom of the rotatable piston 60 with respect to the
slipper assembly 50 to a single axis. Rotation of the rotatable
piston 60 is restricted to rotation about a single bore axis of
rotation 608 and is further dependent on rotation of the joined
slipper assembly 50. Such a restricted rotation of the rotatable
piston 60 provides for less frictional resistance of the rotatable
piston 60 within the cylinder bore 101 leading to greater
efficiency during reciprocating operation of the rotatable piston
60. Thus, a planar fluid bearing proximal interface 401 of the
rotating swashplate 40 described herein is joined to the rotatable
piston 60 by a slipper assembly 50 having a revolute joint
connection therebetween to form a revolute joint piston-slipper
assembly.
[0077] The proximal interface 401 of the rotating swashplate 40 is
disposed at an adjustable angle with respect to a shaft axis of
rotation 301, such as in a variable displacement machine to control
the volumetric displacement of fluid. It is within the scope of
this disclosure that the proximal interface 401 of the rotating
swashplate 40 is disposed at a fixed angle with respect to a shaft
axis of rotation 301, such as in a fixed displacement machine.
[0078] In an embodiment as a variable displacement machine, the
proximal interface 401 of the rotating swashplate 40 is configured
to adjust the adjustable angle with respect to the shaft axis of
rotation 301 as the rotatable shaft 30 rotates such that a
corresponding rotation of the rotating swashplate 40 forces the
revolute joint piston-slipper assembly into a cylinder bore 101
having a bore longitudinal axis configured to act as a bore axis of
rotation 608 for the rotatable piston 60. Further, a hold down
plate 70 is configured to pull the revolute joint piston-slipper
assembly out of the cylinder bore 101 by forcibly maintaining
parallel contact between a planar proximal interface 401 of the
rotating swashplate 40 and a planar distal interface 501 of each
slipper assembly 50. The planar distal interface 501 of each
slipper assembly 50 is configured to slide, in parallel, about the
planar proximal interface 401 of the rotating swashplate 40.
Further, each slipper assembly 50 may be translated in any
direction perpendicular to a slipper assembly interface normal axis
N.sub.SL. Each slipper assembly interface normal axis N.sub.SL is
normal to the planar distal interface 501 of each slipper assembly
50 and may be parallel to a rotating swashplate interface normal
axis N.sub.SW. The rotating swashplate interface normal axis
N.sub.SW is normal to the planar proximal interface 401 of the
rotating swashplate 40. Further, each slipper assembly 50 may be
rotated about a respective slipper assembly interface normal axis
N.sub.SL or a rotational axis parallel to the respective slipper
assembly interface normal axis N.sub.SL.
[0079] Such a revolute joint piston-slipper assembly interacting
and interfacing with a planar fluid bearing proximal interface 401
of a rotating swashplate 40 as described herein, and that is
configured to maintain a parallel orientation to an inclined plane
of the rotating swashplate, provides a rotational phase. The
revolute joint piston-slipper assembly is forced to maintain a 1:1
rotational phase with the rotating swashplate 40 and the rotatable
shaft 30. The revolute joint piston-slipper assembly allows for the
rotatable piston 60 and the slipper assembly 50 to rotate and pivot
relative to one another about a single axis of rotation while
constraining all other degrees of freedom such as translation and
rotation about other axes as described herein. Relative motion
between the revolute joint piston-slipper assembly and forces of
the rotating swashplate 40 force the rotation and translation of
the rotatable piston 60 relative to the cylinder bore 101 about a
bore axis of rotation 608, where rotation of the rotatable piston
60 about the bore axis of rotation 608 reduces friction forces and
improves mechanical efficiency of the axial piston machine 100.
Rotation of the rotatable piston 60 relative to the cylinder bore
101 prevents the rotatable piston 60 from developing a static
friction mode in which the rotatable piston 60 has stopped moving,
such that the rotating rotatable piston 60 continually applies a
dynamic friction resulting in a lower startup torque and an
improved mechanical efficiency over a non-rotating piston incurring
static friction.
[0080] Further, each slipper assembly 50 includes a hydrostatic
bearing feature as described below to allow for a balance of fluid
pressure forces acting on the revolute joint piston-slipper
assembly. In an embodiment, and referring to FIG. 5, each slipper
assembly 50 includes a hydrostatic pocket 505 defined by the distal
interface 501 of the slipper assembly 50. Further, each slipper
assembly 50 includes a lubrication port 506 in fluid communication
with the hydrostatic pocket 505. In embodiments, the rotatable
piston 60 further includes a lubrication port 606 in fluid
communication with the valve passage 603. The lubrication port 606
of the rotatable piston 60 is in fluid communication with the
lubrication port 506 of a respectively joined slipper assembly 50.
The hydrostatic pocket 505 and the lubrication port 506 of each
slipper assembly 50 and the lubrication port 606 and valve passage
603 of each piston 60 are configured to operate together to form a
piston-slipper fluid pressure profile to create a pressure
differential and provide for sealing and bearing lubrication.
[0081] For example, high working fluid pressure in the hydrostatic
pocket 505 and the lubrication port 506 of each slipper assembly 50
and the lubrication port 606 and valve passage 603 of each piston
60 operate against a leakage pressure drop against the cylinder
bore interface 601 of each piston 60 and the distal interface 501
and the revolute joint interface 502 of each slipper assembly 50.
Fluid leakage is driven through small clearances in the rotatable
piston valve assembly 90 through such a pressure differential
between these locations that is a function of a piston-bore chamber
pressure being greater than outer swash housing pressure based on
fluid inside the swash housing 20 that surrounds the rotatable
piston valve assembly 90, the rotating swashplate 40, and the
rotatable shaft 30. The lubrication port 606 is disposed within the
rotatable piston 60 and is in fluid communication with the
lubrication port 506 disposed within the slipper assembly 50 to
feed fluid into the hydrostatic pocket 505 and assist with
balancing a majority of the piston-bore fluid pressure forces.
[0082] The forces react approximately equal and opposite to one
another to provide an adequate balance and limited friction. For
example, a pressure within the hydrostatic pocket 505 creates a
force that is almost equal and opposite to a force of a piston
chamber pressure on the rotatable piston 60. The hydrostatic pocket
505 disposed between the distal interface 501 of the slipper
assembly 50 and the proximal interface 401 of the rotating
swashplate 40 provides for a restriction to leakage within the
hydrostatic pocket 505, which leakage provides fluid-film bearing
lubrication and support between the distal interface 501 of the
slipper assembly 50 and the proximal interface 401 of the rotating
swashplate 40. Similarly, a piston-slipper interface between the
revolute joint interface 604 of the rotatable piston 60 and the
revolute joint interface 502 of the slipper assembly 50 is
lubricated by fluid leakage flow through a small operating
clearance gap between the lubrication port 606 of the rotatable
piston 60 and the lubrication port 506 of the slipper assembly
50.
[0083] Each slipper assembly 50 interfaces against the rotating
swashplate 40 by a planar joint formed by the interfacing
interaction between the distal interface 501 of the slipper
assembly 50 and the proximal interface 401 of the rotating
swashplate 40. During operation, the distal interface 501 of the
slipper assembly 50 and the proximal interface 401 of the rotating
swashplate 40 remain in parallel due to forces pushing against the
rotatable piston 60 and the slipper assembly 50 in a direction
toward the rotating swashplate 40. Such forces are provided by
fluid and friction forces from the cylinder bore 101 on the
rotatable piston 60, and additionally by hold down forces as
described above from the hold down plate 70 on the slipper assembly
50 in an embodiment including the hold down plate 70.
[0084] In embodiments, and referring to FIG. 5, the axial piston
machine 100 may include a manifold 110 disposed within the
stationary cylinder block 10 and the swash housing 20. The manifold
110 is configured for fluid communication with the rotatable piston
assembly 88 and includes the proximal manifold port 106, a proximal
manifold passage 104 in fluid communication with the proximal
manifold port 106, the distal manifold port 202, a distal manifold
passage 105 in fluid communication with the distal manifold port
202, an inward cylinder block port 102, and an outward cylinder
block port 103. The proximal manifold port 106 is disposed at a
proximal end of the manifold 110 within the stationary cylinder
block 10, and the proximal manifold passage 104 includes a
plurality of proximal manifold passage port openings. The inward
cylinder block port 102 is disposed in the stationary cylinder
block 10 and is in fluid communication with one of the plurality of
proximal manifold passage port openings of the proximal manifold
passage 104. The distal manifold port 202 is disposed along a side
wall of the manifold 110 in the swash housing 20 distal to the
proximal end of manifold 110, and the distal manifold passage 105
includes a distal manifold passage port opening. The outward
cylinder block port is in fluid communication with the distal
manifold passage port opening of the distal manifold passage
105.
[0085] In an embodiment, the rotatable piston assembly 88 may
include a plurality of pistons 60, a plurality of slipper
assemblies 50, and a respective plurality of outward cylinder block
ports 103. Each slipper assembly 50 may be coupled to a respective
piston 60 as described herein, and each piston 60 includes an
integral valve port 602. Further, each piston 60 abuts one of the
inward cylinder block ports 102 that is in fluid communication with
one of the plurality of proximal manifold passage port openings of
the proximal manifold passage 104. Additionally, each piston 60
abuts one of the plurality of outward cylinder block ports 103 that
are in fluid communication with the distal manifold passage
105.
[0086] Referring to FIGS. 8A-9H, while positional operation of the
rotatable piston valve assembly 90 with respect to a process for
using an axial piston machine 100 as a pump and a motor is
illustrated, similar positional operation of the rotatable piston
assembly 88 that may include a separate, non-integral valve rather
than the integral piston valve as described herein with respect to
the rotatable piston valve assembly 90 is contemplated within the
scope of this disclosure. The axial piston machine 100 includes the
rotating swashplate 40, the stationary cylinder block 10, and the
rotatable shaft 30 coupled to the rotating swashplate 40. The
rotatable piston assembly 88 includes a rotatable piston 60, as
described herein, that is reciprocated in a cylinder bore 101 of
the stationary cylinder block 10 of the axial piston machine 100.
In an embodiment including the rotatable piston valve assembly 90,
the rotatable piston 60 includes an integral valve port 602
configured to provide a passage for fluid flow in one of a pump
direction and a motor direction opposite the pump direction to
respectively act as one of the pump and the motor. It is
contemplated within the scope of this disclosure that operation of
the piston in a first direction as the pump direction and a second,
opposite direction as the motor direction as described herein may
alternatively be an operation of the piston in the first direction
to operate in the motor direction and the second, opposite
direction as the pump direction. When the pump direction and the
motor direction is described herein with respect to operation of
the axial piston device to operate as a pump or a motor, it is to
be understood that action as a pump is configured to provide for an
intake of a low pressure fluid and a discharge of a high pressure
fluid with respect to the axial piston device, and that action as a
motor is configured to provide for an intake of a high pressure
fluid and a discharge of a low pressure fluid with respect to the
axial piston device, which may be any of the axial piston devices
as described herein.
[0087] Further, while the pump direction and the motor direction is
described herein with respect to operation of the axial piston
device to operate as a pump or a motor, it is further contemplated
within the scope of this disclosure that pumping or motoring may
reference local fluid flow with respect to an operation of the
rotatable piston within a cylinder bore of the axial piston device
as described herein. By way of example, and not as a limitation, an
action of driving a rotatable piston into a cylinder bore to align
a piston valve, whether integral or separate from the rotatable
piston, with a discharge cylinder port to discharge fluid into the
cylinder port may be referenceable as a pumping operation of the
rotatable piston to pump fluid from the rotatable piston with
respect to local fluid flow. Further, an action of driving a
rotatable piston out of and away from the cylinder bore to align a
piston valve, whether integral or separate from the rotatable
piston, with an intake cylinder port to receive fluid into the
rotatable piston from the intake cylinder port may be referenceable
as a motoring operation of the rotatable piston to provide or motor
fluid into the rotatable piston with respect to local fluid
flow.
[0088] The rotatable piston 60 is rotated in the cylinder bore 101
during reciprocation, and rotation of the rotatable piston 60 in
the cylinder bore 101 is controlled through a rotational control
assembly. As a non-limiting example, the rotation control assembly
includes a plurality of rotatable pistons 60 and a plurality of
slipper assemblies 50, each slipper assembly 50 joined with a
rotatable piston 60 through a revolute joint connection, and each
slipper assembly 50 disposed against an interface of the rotating
swashplate 40, which is disposed at an adjustable angle with
respect to a shaft axis of rotation 301 within an angle range
between a first angle and a second angle opposite the first angle.
Rotation of the rotating swashplate 40 is configured to rotate the
rotational control assembly as described herein.
[0089] In embodiments, the rotatable shaft 30 is rotated about the
shaft axis of rotation 301 to rotate the rotating swashplate 40
about the shaft axis of rotation 301. The plurality of slipper
assemblies 50 of the rotatable piston valve assembly 90 rotate
through rotation of the rotating swashplate 40, and the plurality
of rotatable pistons 60 rotate about the bore axis of rotation 608
through rotation of the plurality of slipper assemblies 50. The
plurality of slipper assemblies 50 are respectively joined to the
plurality of rotatable pistons 60 through, for example, respective
revolute joint connections.
[0090] As described above, the axial piston machine 100 includes a
manifold 110 disposed within the stationary cylinder block 10 and
the swash housing 20. When the axial piston machine 100 acts as a
pump, as shown in FIGS. 8A-8D, for example, fluid is received in
the pump direction flowing from a proximal end of the manifold 110
toward a distal side portion of the manifold 110 into the proximal
manifold port 106 disposed at the proximal end of the manifold 110
within the stationary cylinder block 10. Fluid is further received
into the proximal manifold passage 104 from the proximal manifold
port 106, and fluid is received into a plurality of inward cylinder
block ports 102 disposed in the stationary cylinder block 10
through respective openings of the proximal manifold passage 104.
It is contemplated within the scope of this disclosure that the
axial piston devices described herein may operate as a pump or a
motor configured for fluid flow in a variety of directions, such as
in one of four directions with respect to FIGS. 8A-8D. By way of
example, and not as a limitation, the axial piston device 100 may
operate (1) as a pump configured to utilize the proximal manifold
port 106 as a discharge outlet, (2) as a pump configured to utilize
the distal manifold passage 105 as a discharge outlet, (3) as a
motor configured to utilize the proximal manifold port 106 as a
discharge outlet, or (4) as a motor configured to utilize the
distal manifold passage 105 as a discharge outlet. It is further
contemplated within the scope of this disclosure that rotation in a
first direction, such as a clockwise direction, to operate the
axial piston device as one of a pump or a motor is configured to be
reversed to a second direction opposite the first direction, such
as a counter-clockwise direction, to reverse or flip the manifold
and fluid flow direction such that the axial piston device may
operate as the other of the pump or the motor.
[0091] When the integral valve port 602 of a rotatable piston 60 of
the plurality of rotatable pistons 60 is in fluid communication
with a respective inward cylinder block port 102 as shown in FIGS.
8C and 9E, fluid is received into the integral valve port 602 to
flow into the valve passage 603 of the rotatable piston 60. As the
rotatable piston 60 rotates in the direction of arrow A to advance
to a position shown in FIG. 9F, fluid communication between the
respective inward cylinder block port 102 and the integral valve
port 602 becomes more restricted. When the rotatable piston 60 is
in the position shown in FIG. 9G, that corresponds to a position
shown in FIG. 8D, the respective inward cylinder block port 102 is
disengaged from the integral valve port 602.
[0092] As shown in FIGS. 8A and 9A, when the integral valve port
602 of the rotatable piston 60 is in fluid communication with a
respective outward cylinder block port 103 of a plurality of
outward cylinder block ports 103 disposed in the stationary
cylinder block 10, fluid is directed from the valve passage 603 to
flow through the integral valve port 602 and into the respective
outward cylinder block port 103. Fluid is received into the distal
manifold passage 105 that is in fluid communication with the
plurality of outward cylinder block ports 103 and is discharged
from the distal manifold port 202 in fluid communication with the
distal manifold passage 105. As the rotatable piston 60 continues
to rotate in the direction of arrow A to advance to a position
shown in FIG. 9B, fluid communication between the respective
outward cylinder block port 103 and the integral valve port 602
becomes more restricted. When the rotatable piston 60 is in the
position shown in FIG. 9C, that corresponds to a position shown in
FIG. 8B, the respective outward cylinder block port 103 is
disengaged from the integral valve port 602.
[0093] When flow of fluid is in the pump direction, provided
rotational movement of the rotatable shaft 30 rotates the rotating
swashplate 40 to, in turn, rotate the rotatable piston valve
assembly 90, and mechanical energy from rotating the rotatable
shaft 30 is converted to hydraulic energy from the flow of fluid in
the pump direction. For example, such rotational movement is
provided by driving the rotatable shaft 30 by an external torque T
at a rotational speed w, as shown in FIGS. 8A-8D, and the external
torque and rotational speed are directly transferred to the
rotating swashplate 40. An external source, such as a motor, may
provide input mechanical power to use of the axial piston machine
100 as a pump, as the external torque T and the rotation speed w
provided to the rotatable shaft 30 through an external drive
feature 302 (FIG. 0.5) disposed on the rotatable shaft 30. The
external drive feature 302 may be a key or spline or like drive
feature connecting the rotatable shaft 30 to connect the rotatable
shaft 30 to the external source. Further, the input torque and
speed is directly transferred from the rotatable shaft 30 to the
rotating swashplate 40 through a swashplate drive feature 303 (FIG.
5), such as a key, connecting the rotatable shaft 30 to the
rotating swashplate 40. Rotation of the rotating swashplate 40
forces a plurality of rotatable pistons 60 to reciprocate
proximally and distally within a plurality of respective cylinder
bore 101 within the stationary cylinder block 10 as described
herein. Each piston 60 is coupled to a slipper assembly 50 as
described herein, such as through a revolute joint that provides
rotational freedom and an axial constraint about the bore axis of
rotation 608, such that translation and rotation of the rotatable
piston 60 about the bore axis of rotation 608 is directly phased to
an axial and rotation position of the slipper assembly 50. As the
slipper assembly 50 interfaces with the rotating swashplate 40
through forces and fluid pressure differentials described herein,
rotation of the rotating swashplate 40 effects a rotation of the
plurality of slipper assemblies 50 and a phased rotation and
translation of the respective plurality of joined rotatable pistons
60 within the plurality of cylinder bores 101. The input mechanical
power is transformed to hydraulic power output as a pressurized
flow discharged from the distal manifold passage 105 and the distal
manifold port 202 as described herein.
[0094] When the axial piston machine 100 acts as a motor, fluid in
the motor direction, opposite the pump direction, is provided from
an external source such as a pump and flows from the distal side
portion of the manifold 110 toward the proximal end of the manifold
110 into the distal manifold port 202 of the manifold 110. Fluid
into the distal manifold passage 105 from the distal manifold port
202, the distal manifold passage 105 in fluid communication with
the distal manifold port 202 and a plurality of outward cylinder
block ports 103 disposed in the stationary cylinder block 10. When
the integral valve port 602 of a rotatable piston 60 of the
plurality of rotatable pistons 60 is in fluid communication with a
respective outward cylinder block port 103 of a plurality of
outward cylinder block ports 103, as shown in FIG. 9A, fluid is
received into the integral valve port 602 from the distal manifold
passage 105 and respective outward cylinder block port 103 and into
the valve passage 603 of the rotatable piston 60 through the
integral valve port 602. When the integral valve port 602 of the
rotatable piston 60 is in fluid communication with a respective
inward cylinder block port 102 of a plurality of inward cylinder
block ports 102 disposed in the stationary cylinder block 10, as
shown in FIG. 9E, fluid is received into the respective inward
cylinder block port 102 from the integral valve port 602. Fluid is
then received into a respective opening of a plurality of openings
of a proximal manifold passage 104, which plurality of openings of
the proximal manifold passage 104 are in respective fluid
communication with the plurality of inward cylinder block ports
102. Fluid flows for receipt into the proximal manifold port 106
from the proximal manifold passage 104 and is discharged from the
proximal manifold port 106. When flow of fluid is in the motor
direction, the rotatable piston valve assembly 90 translates
through the flow of fluid to rotate the rotating swashplate 40 to,
in turn, rotate the rotatable shaft 30 and convert hydraulic energy
from the flow of fluid in the motor direction to mechanical energy
from rotation of the rotatable shaft 30. As a non-limiting example,
motor fluid flow pressure forces the rotatable piston 60 of the
rotatable piston valve assembly 90 to translate into the rotating
swashplate 40, and an angle of the planar proximal interface 401 of
the rotating swashplate 40 receiving this thrust load forces the
rotating swashplate 40 to rotate. The slipper revolute joint forces
the rotating piston 60 to spin and rotate along with the rotating
swashplate 40 as the slipper assembly 50 is being rotationally
forced in parallel with the planar proximal interface 401 of the
rotating swashplate 40.
[0095] As the rotatable piston 60 rotates within a cylinder bore
101 at a rotational piston speed Wp, the rotatable piston 60 is
additionally translated within the bore in a translation along the
bore axis of rotation 608 at a translational piston velocity Vpn. A
directional and axial position of the integral valve port 602
relative to a respective cylinder bore 101 is constantly changing
as the rotating swashplate 40 rotates and forces rotation and
translation of the rotatable piston 60 about the bore axis of
rotation 608 that is coaxial with a cylinder bore axis of
rotation.
[0096] By way of example, and not as a limitation, a position of
the rotatable piston 60 in the cylinder bore 101 in FIG. 8A
corresponds to a position of the rotatable piston 60 in FIG. 9A
with respect to the integral valve port 602. In FIG. 8A, the
integral valve port 602 of the rotatable piston 60 is aligned with
the distal manifold port 202 such that a translational piston
velocity Vpn translates the rotatable piston 60 in a direction
toward a proximal end of the cylinder bore 101. As shown in FIG.
9A, a proximal end of the rotatable piston 60 is spaced from the
proximal end of the cylinder bore 101 allowing for such proximal,
upward translation of rotatable piston 60. As the rotatable piston
60 rotates in the direction of arrow A, as shown in FIGS. 9A-9B,
and moves from the position shown in FIG. 8A (corresponding to FIG.
9A) toward the position of FIG. 8B (corresponding to FIG. 9C), the
proximal end of the rotatable piston 60 translates proximally
toward the proximal end of the cylinder bore 101, as illustrated by
the proximally directed, upward Vpn arrow of FIG. 8A. In FIG. 9C,
corresponding to the position of the rotatable piston 60 shown in
FIG. 8B, the proximal end of the rotatable piston 60 is at a
closest distance with respect to the proximal end of the cylinder
bore 101 and will not proximally translate further in the cylinder
bore 101, such that the translation piston velocity may be set to
zero (Vpn=0). At such a position, the proximal interface 401 of the
rotating swashplate 40 may be angled at a first angle with respect
to the shaft axis of rotation 301.
[0097] As the rotatable piston 60 continues to rotate in the
direction of arrow A, as shown in FIGS. 9C-9D, and moves from the
position shown in FIG. 8B (corresponding to FIG. 9C) toward the
position of FIG. 8C (corresponding to FIG. 9E), the proximal end of
the rotatable piston 60 translates distally toward a distal end of
the cylinder bore 101, as illustrated by the distally directed,
downward Vpn arrow in FIG. 8C. Further, as the rotatable piston 60
continues to rotate in the direction of arrow A, as shown in FIGS.
9E-9F, and moves from the position shown in FIG. 8C (corresponding
to FIG. 9E) toward the position of FIG. 8D (corresponding to FIG.
9G), the proximal end of the rotatable piston 60 continues to
translate distally toward a distal end of the cylinder bore 101, as
illustrated by the distally directed, downward Vpn arrow in FIG.
8C.
[0098] In FIG. 9G, corresponding to the position of the rotatable
piston 60 shown in FIG. 8D, the proximal end of the rotatable
piston 60 is at a furthest distance with respect to the proximal
end of the cylinder bore 101 and will not distally translate
further in the cylinder bore 101, such that the translation piston
velocity may again be set to zero (Vpn=0). At such a position, the
proximal interface 401 of the rotating swashplate 40 may be angled
at a second angle opposite the first angle with respect to the
shaft axis of rotation 301. As the rotatable piston 60 rotates in
the direction of arrow A, as shown in FIGS. 9G-9H, and moves from
the position shown in FIG. 8D (corresponding to FIG. 9G) toward the
position of FIG. 8A (corresponding to FIG. 9A), the proximal end of
the rotatable piston 60 begins to translate proximally again toward
the proximal end of the cylinder bore 101, as illustrated by the
proximally directed, upward Vpn arrow of FIG. 8A.
[0099] Each rotatable piston 60 includes an integral valve port 602
defined within a cylinder bore interface 601 that cooperates with a
respective inward cylinder block port 102 and a respective outward
cylinder block port 103 of a respective cylinder bore 101 to
control a distribution of flow to the cylinder bore 101 from either
the proximal manifold passage 104 or the distal manifold passage
105 depending on a direction of flow as described herein. The valve
passage 603 defined within the cylinder bore interface 601 of the
rotatable piston 60 is configured to assist with providing a
constant flow path between the cylinder bore 101 and the integral
valve port 602, a position of which with respect to the cylinder
bore 101 is constantly changes as the rotatable piston 60 rotates
and translates within the cylinder bore 101. A position of the
integral valve port 602 relative to the respective inward cylinder
block port 102 and the respective outward cylinder block port 103
controls a distribution of flow through the continuously changing
orifice area that is the area of port overlap between the integral
valve port 602 and the respective inward cylinder block port 102 or
the respective outward cylinder block port 103. Further, timing of
rotational and translation movement of the integral valve port 602
is directly phased with the rotation and translation of rotatable
piston 60.
[0100] For example, as the rotatable piston 60 is forced to
translate proximally into the cylinder bore 101 through rotation of
the slipper assembly 50 and the rotating swashplate 40 as described
herein, the integral valve port 602 is moved to an outward position
to fluidly communicate with the respective outward cylinder block
port 103, as shown in FIGS. 8A and 9A. A sizing of the integral
valve port 602 may be such that the integral valve port 602 is open
to one of the respective inward cylinder block port 102 and the
respective outward cylinder block port 103 at a time. Thus, while
the integral valve port 602 is open to and in fluid communication
with the respective outward cylinder block port 103, the cylinder
bore interface 601 seals off the respective inward cylinder block
port 102 from the valve passage 603.
[0101] As the rotatable piston 60 reaches an end of a proximal
translation stroke as illustrated in FIGS. 8B and 9C, the integral
valve port 602 is in a forward intermediate position and closes off
from the respective outward cylinder block port 103 and is also
closed off from the respective inward cylinder block port 102. As
the rotatable piston 60 begins to be distally translated out from
the cylinder bore 101, the integral valve port 602 begins to open
up to the respective inward cylinder block port 102 into an inward
position as shown in FIG. 8C to provide a flow path for fluid
between the proximal manifold passage 104, the valve passage 603,
and the cylinder bore 101. As the rotatable piston 60 reaches an
end of a distal translation stroke as illustrated in FIGS. 8D and
9G, the integral valve port 602 is in a rearward intermediate
position and closes off from the respective inward cylinder block
port 102 and is also closed off from the respective outward
cylinder block port 103. While valve port timing is described
herein as a line to line porting that closes the integral valve
port 602 off from both the respective outward cylinder block port
103 and the respective inward cylinder block port 102 at certain
rotational positions in time, it is within the scope of this
disclosure that closed and open porting techniques may be used such
that the integral valve port 602 does not have to be closed off
from both ports at any point in time.
[0102] The rotatable piston assembly described herein including a
rotary piston, such as the rotatable piston 60, configured for
rotational control is able to reduce friction, absorb unbalanced
forces, and have greater performance capabilities over, for
example, a non-rotating piston. A rotational control assembly as
described herein controls rotation of the rotary piston to reduce
static friction and increase piston efficiency in operation when
used with a displacement machine. Further, combining such a
bi-directional valve feature with the rotatable piston 60, as
included through the integral valve port 602 described herein,
removes a need to manufacture a separate valve component to operate
with the piston and provides a lighter, integrated single component
including both the piston and the valve.
[0103] The present disclosure with respect to at least FIGS. 10-27
is directed to a rotating swash mechanism type axial piston machine
with a stationary cylinder block that can operate as a pump or a
motor, though a stationary swash mechanism type piston machine with
a rotating cylinder block with components and functionality as
described herein to effect a controlled piston rotation is
contemplated within the scope of this disclosure. As a pump, the
axial piston machine acts to transfer mechanical energy to
hydraulic energy by receiving torque and rotational speed through
the shaft, and directing that received energy to a plurality of
reciprocating pistons to displace pressurized fluid. In one
non-limiting example, the swash mechanism is a swashplate. A
rotating swashplate type axial piston machine with a stationary
cylinder block may include a mechanically phased rotary valve,
rather than a check-valve, along with a shaft-valve to provide for
use of the rotating swashplate type axial piston machine as a pump
and/or motor, and assist with absorbing unbalanced forces.
[0104] Another rotating swashplate type axial piston machine with a
stationary cylinder block may include a rotational piston with an
integral mechanically phased valve to provide for use of the
rotating swashplate type axial piston machine as a pump and motor
and assist with absorbing unbalanced forces.
[0105] The present disclosure with respect to at least FIGS. 10-13
describes a fixed, tilted displacement assembly including a
plurality of rotatable piston with valve assemblies that can absorb
unbalanced forces while further allowing for use of the rotating
swash mechanism type axial piston machine as a pump and/or motor
across different hydraulic systems, ranging from low pressure to
high pressure hydraulic systems, such as those operating with loads
at above 3000 psi. The axial piston machine includes bearing
interfaces that act to generally cancel out and balance bearing
forces, allowing for use of the axial piston machine in such high
pressure hydraulic systems.
[0106] The displacement assembly, as described in greater detail
further below, includes a swash collar assembly and may include one
or more hydrostatic pressure pockets to balance forces. A swash
collar of the swash collar assembly includes an angled, machined
bore sized and shaped to receive and couple to the shaft. Upon
rotation of the shaft coupled to the swash collar, the coupled
wobble plate is configured to drive translation of a plurality of
coupled rotatable piston with valve assemblies within the axial
piston machine. One or more hydrostatic pressure pockets may be
configured to cancel bearing forces between opposed pockets and
create a moment coupling to counteract a moment on the wobble
plate, thus assisting to balance forces. While the disclosure
herein describes use of such a fixed, tilted displacement assembly
with a rotating swash mechanism type axial piston machine, it is
within the scope of this disclosure that one or more components of
the displacement assembly described herein may be used with all
fixed and variable displacement reciprocating piston type machines.
By way of example and not limitation, the one or more hydrostatic
pressure pockets as described herein may be used with either fixed
or variable displacement reciprocating piston type machines.
[0107] Referring to FIG. 10, an axial piston machine 1000 is
illustrated. The axial piston machine 1000 may be a fixed
displacement piston machine configured to drive and adjust the
stroke of reciprocating pistons 1006 in a housing 1007 through a
drive mechanism such as a tilted displacement assembly 1060 (FIG.
13) as described herein. Such a tilted displacement assembly 1060
is configured to drive the stroke of the reciprocating pistons 1006
of a plurality of rotatable piston with valve assemblies 1058 to
direct a fluid displacement volume within the housing 1007, as
described in greater detail below.
[0108] As a non-limiting example, the tilted displacement assembly
1060 of the axial piston machine 1000 of FIG. 10 that assists to
drive one or more pistons 1006 may be disposed in a housing 1007.
The tilted displacement assembly 1060 of FIG. 10 includes a shaft
1001, swash collar 1003, wobble plate 1004, slipper 1005, and
piston 1006. The shaft 1001 is configured to transfer torque and
speed between the swash collar 1003 and an external drive shaft and
is coupled to the housing 1007. The shaft 1001 is coupled to the
housing 1007 through a set of shaft support bearings 1199, for
example. The swash plate 1003 includes a bore that may be machined
and angled such that the bore is sized and shaped to receive and
couple to the shaft 1001. In some embodiments, a hydrostatic
pressure pocket on a partial circumference of the shaft 1001 in
communication with shaft fluid passages is included. Addition of
such a hydrostatic pressure pocket may improve bearing capabilities
of the shaft 1001, and minimize loads on the shaft support bearings
1199.
[0109] The swash collar 1003 is coupled to the shaft 1001 about a
pin axis 1200 of pin 1002 disposed generally perpendicular to a
longitudinal shaft axis 1100. Referring to FIG. 11, a tilt angle of
the swash collar 1003, also referable to as a swash angle, is
defined with respect to the shaft 1001, and particularly the pin
axis 1200 of the pin 1002 coupled to the shaft 1001. Machines
including a fixed swash angle as described herein are fixed
displacement machines, and those including an adjustable swash
angle are variable displacement machines. While the present
disclosure describes use of a rotatable piston with valve assembly
with respect to the axial piston machine 1000 as a fixed
displacement machine, either such fixed or variable displacement
machines may be used with the rotatable piston with separate or
integral valve assemblies as described herein and are within the
scope of the present disclosure.
[0110] FIG. 10 shows the wobble plate 4 at a fixed angle tilted
with respect to the pin axis 1200 of the pin 1002 in a forward to
backward tilt view. FIG. 11 shows the wobble plate 1004 in a
side-to-side tilt view rotated 90 degrees clockwise from the view
of FIG. 10 to show another view of the fixed angle tilted with
respect to the pin axis 1200 of the pin 1002 that is generally
perpendicular to the longitudinal shaft axis 1100 of the shaft
1001.
[0111] A plurality of piston slipper assemblies 1056, as described
in greater detail further below, may be loaded such that net
component forces of axial and radial forces acting upon the wobble
plate 1004 may be mostly balanced and wobble plate support bearings
1499 will only to need to support moment loads of the piston
forces. The wobble plate support bearings 1499 may then carry such
moment loads with radial forces and limit a risk of issues that may
arise with bearing tip, which may exist if axial bearings were
instead used. A radial load support allows for smaller bearings to
be used than would be used for an axial load support, which in turn
may allow for a smaller overall machine envelope size and a
reduction in cost and power losses. It is contemplated that other
bearing types would be useful and effective in these embodiments,
e.g., other roller bearing types and plain bearings that may or may
not be hydrostatic bearings. By way of example and not as a
limitation, the bearings described herein may be roller bearings,
plain bearings, hydrostatic bearings, and fluid dynamic bearings.
For example, a roller bearing may be used for applications desiring
simplicity, availability, and low friction as provided by roller
bearings, while a fluid bearing may be used instead of a roller
bearing to accommodate for a smaller package size. Such fluid
bearings utilized within the assembly and machine described herein
may be configured to supply pressurized fluid to and from and
between, respectively, the piston 1006, the slipper 1005, the
wobble plate 1004, the swash collar 1003, the swash pin 1002, the
shaft 1001, and the housing 1007.
[0112] The wobble plate 1004 is further configured to support
forces from a working fluid pressure that is displaced by a
plurality of piston slipper assemblies 1056 cooperating with the
plurality of pistons 1006. Referring to FIGS. 10-13, each piston
slipper assembly 1056 includes a piston 1006 coupled to a slipper
1005 through a fastener such as a slipper pin 1599. The wobble
plate 1004 includes two opposed wobble plate bearing surfaces 1401.
In an embodiment, the two wobble plate bearing surfaces 1401 are
parallel to one another. The wobble plate bearing surfaces 1401 are
coupled to a respective plurality of slipper surfaces 1501 of each
slipper 1005.
[0113] In operation, the shaft 1001 may rotate either
counter-clockwise or clockwise to effect a corresponding piston
1006 reciprocation. Torque and speed are transferred from the
rotating shaft 1001 to the wobble plate 1004 through such couplings
as described herein. An external motor may drive and provide torque
and speed to the shaft 1001. The shaft 1001 in turn drives the pin
1002, which drives the swash collar 1003 and the wobble plate 1004
to effect translation of the pistons 1006 that are contained within
respective piston bores defined within the housing 1007 of the
stationary cylinder block. Slippers 1005 are coupled to respective
pistons 1006 housed within the piston bores. The wobble plate 1004
includes interior surfaces 1401 that are disposed about slipper
surfaces 1501 of each slipper 1005, and each slipper 1005 may
slidably rotate within and with respect to the wobble plate 1004
through interfacing surfaces 1401, 1501 and in alignment with
rotation of the shaft 1001, for example. As shown in FIGS. 10-11,
during rotation, each slipper pin 1599 may initially be configured
to face the same direction as the pin 1002 coupling the swash
collar 1003 to the shaft 1001 and may rotate in alignment with the
pin 1002 as the shaft 1001 rotates to effect a corresponding
rotation of the slippers 1005. Rotation of each slipper 1005
effects a corresponding rotation of a respective piston 1006 to
which the slipper 1005 is attached through the slipper pin
1599.
[0114] Referring to FIGS. 12-13, the piston slipper assembly 1056
is shown as a rotatable piston with valve assembly 1058, a
plurality of which are shown in FIG. 13 as part of the tilted
displacement assembly 1060. The rotatable piston with valve
assembly 1058 includes a piston 1006 that includes first end 1062
and a second end 1064 opposing the first end 1062. Each of the
first end 1062 and the second end 1064 respectively include a first
valve port 1602A and a second valve port 1602B. It is contemplated
within the scope of this disclosure that a rotatable piston
assembly having a separate valve may be utilized in place of the
rotatable piston with valve assembly 1058 including at least an
integrated valve in the piston 1006. In an embodiment, a piston
1006 of the rotatable piston with valve assembly 1058 may include a
single valve port 1602. The first valve port 1602A of the first end
1062 and the second valve port 1602B of the second end 1064 are
configured to be 180 degrees apart to communicate with different
cylinder ports of the housing 7, as described below. Other
positions between the first valve port 1602A and the second valve
port 1602B to interact with one or more ports of respective
cylinder bores 1702 to direct fluid through the axial piston
machine 1000 are within the scope of this disclosure.
[0115] Referring to FIG. 12, a slipper pin 1599 connects the
slipper 1005 and the piston 1006 and is configured to be sized and
shaped for receipt into respective bores of the slipper 1005 and
the piston 1006 to lock the components together. The slipper pin
1599 acts to form the revolute joint connecting the slipper 1005 to
the piston 1006 to constrain relative motion between the piston
1006 and the slipper 1005. As described above, the slipper 1005
includes opposing bearing surfaces 1501 configured to interact with
wobble plate bearing surfaces 1401 as the slipper 1005 rotates
through connection with the wobble plate 1004 and rotation of the
shaft 1001. In an embodiment, the opposing bearing surfaces 1501
may be fluidly connected with respective first and second ends
1062, 1064 of the piston 1006 such that a majority of fluid
pressure forces are balanced during rotational operation. As the
slipper 1005 rotates, the slipper pin 1599 forming the revolute
joint allows tilt of the piston 1006 within the slipper 1005 but
does not permit independent translation and rotational movement of
the piston 1006 with respect to the slipper 1005. Rotation of the
slipper 1005 drives a corresponding rotation of the piston 1006
joined through the slipper pin 1599 such that the slipper 1005 and
the piston 1006 are synchronously coupled in rotation and
translation movement.
[0116] Each of the first end 1062 and the second end 1064 of each
piston 1006 additionally include a cylinder bore interface 1601
configured to translationally interface with a respective piston
bore 1710 as shown in FIGS. 10-11. As shown in a position of FIG.
10, the first valve port 1602A is configured to communicate with a
cylinder port 1702 of the piston bore 1710A while the second valve
port 1602B is open to and communicates with a cylinder port 1703 of
the piston bore 1710B. As the first end 1062 of the piston 1006
translates upwardly into a respective piston bore 1710A, the second
end 1064 moves upwardly out of a respective piston bore 1710B.
Through such translation and upward movement, as shown between
FIGS. 10-11, the piston 1006 rotates to a position such that
neither the first valve port 1602A nor the second valve port 1602B
are in communication with the cylinder ports 1702, 1703, as shown
in FIG. 12, and therefore are closed with respect to the cylinder
ports 1702, 1703.
[0117] As the piston 1006 continues to rotate, the first end 1062
of the piston 1006 will translate downwardly out of the respective
piston bore 1710A, and the second end 1064 will translate
downwardly into the respective piston bore 1710B. In such a
position, the first valve port 1602A is configured to communicate
with the cylinder port 1703 of the piston bore 1710A while the
second valve port 1602B is open to and communicates with the
cylinder port 1702 of the piston bore 1710B. As the piston 1006
continues to rotate, the first end 1062 of the piston 1006 will
begins to translate upwardly into the respective piston bore 1710A,
and the second end 1064 will translate upwardly out of the
respective piston bore 1710B to arrive back at the position of FIG.
10. In an embodiment, such as when operating as a pump, for
example, fluid may be received from the cylinder port 1703 of the
piston bores 1710A, 1710B when in open communication with a
respective valve port 1602A, 1602B, and fluid may be sent out
through the cylinder port 1702 of the piston bores 1710A, 1710B
when in open communication with the respective valve port 1602A,
1602B.
[0118] The axial piston machine 1000 described herein is a
reciprocating piston device utilizing fixed displacement and
balanced bearing forces to enable operation in high pressure
hydraulic systems with a smaller structure, increased efficiency
and control, and reduced noise that can be realized through use of
the double-sided wobble plate drive mechanism. Such a double-sided
wobble plate drive mechanism as described herein provides for a
reduction in rotating mass (i.e., moment of inertia) leading to an
increased shaft rotational acceleration, a reduction in swash mass
leading to faster fluid displacement control, a compact design
leading to reduced material and use cost and a smaller envelope
size of the machine, a piston configuration leading to a reduction
in flow ripple, noise, and friction, and a rotating swash collar
assembly including balanced loads leading to improved efficiency
and reduced structural noise transmitted to the housing through
bearings. Commercial uses for the axial piston machine 0 include
use as a piston pump, motor, engine, or compressor. These often
find application in the drive and control industry on equipment.
Such equipment includes stationary industrial equipment and mobile
equipment such as vehicles, aircraft, ships, and the like.
[0119] The present disclosure with respect to at least FIGS. 14-27
describes a variable displacement assembly that can absorb
unbalanced forces while further allowing for use of the rotating
swash mechanism type axial piston machine as a pump and/or motor
across different hydraulic systems, ranging from low pressure to
high pressure hydraulic systems operating with loads at above 3000
psi. The axial piston machine includes bearing interfaces that act
to generally cancel out and balance bearing forces, allowing for
use of the axial piston machine in such high pressure hydraulic
systems.
[0120] The variable displacement assembly, as described in greater
detail further below, includes a swash collar assembly including
one or more hydrostatic pressure pockets to balance forces; and a
piston and spring assembly configured to control tilt of a wobble
plate coupled to a swash collar. Upon rotation of the swash collar
through rotation of a coupled shaft, the wobble plate is configured
to tilt with respect to the shaft through use of the piston and
spring assembly and to drive pistons within the axial piston
machine. The one or more hydrostatic pressure pockets are
configured to cancel bearing forces between opposed pockets and
create a moment coupling to counteract a moment on the wobble
plate, thus assisting to balance forces. While the disclosure
herein describes use of such a variable displacement assembly with
a rotating swash mechanism type axial piston machine, it is within
the scope of this disclosure that one or more components of the
variable displacement assembly described herein may be used with
all fixed and variable displacement reciprocating piston type
machines, including, but not limited to, a rotating cylinder block
type axial piston machine. By way of example and not limitation,
the one or more hydrostatic pressure pockets may be used with
either fixed or variable displacement reciprocating piston type
machines.
[0121] Referring to FIG. 14, an axial piston machine 2000 is
illustrated. The axial piston machine 2000 may be a positive
displacement variable piston machine configured to drive and adjust
the stroke of reciprocating pistons 2006 in a housing 2007 through
an adjustment drive mechanism such as a variable displacement
assembly as described herein. Such a variable displacement assembly
is configured to adjust the stroke of the reciprocating pistons
2006 to change a fluid displacement volume within the housing
2007.
[0122] As a non-limiting example, the variable displacement
assembly of the axial piston machine 2000 of FIG. 14 that assists
to drive one or more pistons 2006 may be disposed in a housing
2007. The variable displacement assembly of FIG. 14 includes a
shaft 2001, swash collar 2003, wobble plate 2004, slipper 2005, and
piston 2006. The shaft 2001 is configured to transfer torque and
speed between the swash collar 2003 and an external drive shaft and
is coupled to the housing 2007. The shaft 2001 is coupled to the
housing 2007 through a set of shaft support bearings 2199, for
example. In some embodiments, a hydrostatic pressure pocket on a
partial circumference of the shaft 2001 in communication with shaft
fluid passages 2120, 2130 is included. Addition of such a
hydrostatic pressure pocket may improve bearing capabilities of the
shaft 2001, and minimize loads on the shaft support bearings
2199.
[0123] The swash collar 2003 is tiltably and rotatably coupled to
the shaft 2001 about a pin axis 2200 of pin 2002 (FIG. 16) disposed
generally perpendicular to a longitudinal shaft axis 2100 (FIG.
16). The shaft 2001 is further coupled to the swash collar 2003 of
the variable displacement assembly through a set of swash collar
support bearings 2399 (FIGS. 14-18) and a swash pin 2002. The swash
collar support bearings 2399 are configured to support moment loads
of the piston 2006 and any unbalanced component forces. A packaging
including the swash collar support bearings 2399 is disposed inside
the swash collar 2003, and is configured to limit an effect moment
arm and the load capabilities of the swash collar support bearings
1399.
[0124] Referring to FIG. 15, a tilt angle of the swash collar 2003,
also referable to as a swash angle, is defined with respect to the
shaft 2001, and particularly the pin axis 2200 of the pin 2002
coupled to the shaft 2001. Machines including a fixed swash angle
are fixed displacement machines, and those including an adjustable
swash angle as described herein are variable displacement machines.
FIG. 14 shows the wobble plate 2004 at a tilted angle with respect
to the pin axis 2200 of the pin 2002. FIG. 16 shows the wobble
plate 2004 generally parallel and not tilted to have a zero tilt
angle with respect to the pin axis 2200 of the pin 2002 and
generally perpendicular to the longitudinal shaft axis 2100 of the
shaft 2001.
[0125] Adjustment of the tilt angle controls fluid volume
displacement within the axial piston machine 2000. An adjustment of
the tilt angle of the swash collar 2003 is controlled by a control
piston 2008 and a bias spring 2009. The bias spring 2009 is
supported by the shaft 2001 and is coupled to the swash collar
2003. The bias spring 2009 is configured to force swash collar 2003
to which the bias spring 2009 is coupled to a position of maximum
tilt with respect to the shaft 2001. Additionally, the control
piston 2008 is supported by the shaft 2001 and is coupled to the
swash collar 2003. A control piston chamber 2112 cooperates with
the control piston 2008, such that the control piston 2008 is
configured to reciprocate within a bore defining the control piston
chamber 2112. The control piston chamber 2112 is configured to be
supplied with a pressurized control fluid such that the control
piston 2008 is forced in a direction toward and into the swash
collar 2003. A stroke of the control piston 2008 is adjusted when a
force of the control piston 2008 is great enough to overcome a
moment of the force of the bias spring 2009, in addition to any
unbalanced piston moments. The pressurized control fluid is
supplied to the control piston chamber 2112 by a shaft fluid
passage 2110, 2111 configured to be in fluid communication with a
housing fluid passage 2710, and is supplied and controlled by an
externally coupled flow control device 2799.
[0126] The wobble plate 2004 is coupled to the swash collar 2003
through opposed wobble plate support bearings 2499. These wobble
plate support bearings 2499 may be, for example, a set of angular
contact, tapered roller bearings disposed on first and second ends
of the wobble plate 2004. The set of angular contact, tapered
roller bearings is configured to provide an effective radial load
at a distance from a bearing interface, which provides for a
greater moment arm than a non-angular contact bearing, for example,
resulting in greater moment load capabilities. It is contemplated
that other bearing types would be useful and effective in these
embodiments, e.g., other roller bearing types and plain bearings
that may or may not be hydrostatic bearings. By way of example and
not as a limitation, the bearings described herein may be roller
bearings, plain bearings, hydrostatic bearings, and fluid dynamic
bearings. For example, a roller bearing may be used for
applications desiring simplicity, availability, and low friction as
provided by roller bearings, while a fluid bearing may be used
instead of a roller bearing to accommodate for a smaller package
size. Such fluid bearings utilized within the assembly and machine
described herein may be configured to supply pressurized fluid to
and from and between, respectively, the piston 2006, the slipper
2005, the wobble plate 2004, the swash collar 2003, the swash pin
2002, the shaft 2001, and the housing 2007.
[0127] A plurality of pistons 2006 may be loaded such that net
component forces of axial and radial forces acting upon the wobble
plate 4 may be mostly balanced and wobble plate support bearings
2499 will only to need to support moment loads of the piston
forces. The wobble plate support bearings 2499 may then carry such
moment loads with radial forces and limit a risk of issues that may
arise with bearing tip, which may exist if axial bearings were
instead used. A radial load support allows for smaller bearings to
be used than would be used for an axial load support, which in turn
may allow for a smaller overall machine envelope size and a
reduction in cost and power losses.
[0128] The wobble plate 2004 is further configured to support
forces from a working fluid pressure that is displaced by a
plurality of piston slipper assemblies 2056 cooperating with the
plurality of pistons 2006. It is contemplated within the scope of
this disclosure that the plurality of pistons 2006 may include an
integral valve as described herein or may cooperate with a separate
valve to direct fluid through the axial piston machine 2000. Each
piston slipper assembly 2056 includes a piston 2006 coupled to a
slipper 2005 through a fastener such as a slipper pin 2599. The
wobble plate 2004 includes two opposed wobble plate bearing
surfaces 2401. In an embodiment, the two wobble plate bearing
surfaces 2401 are parallel to one another. The wobble plate bearing
surfaces 2401 are coupled to respective plurality of slipper
surfaces 2501 of each slipper 2005.
[0129] Additional bearing components of the axial piston machine
2000 include hydrostatic pressure pockets 2310 included at an
interface of the swash collar 2003 and the shaft 2001. In
particular, a hydrostatic pressure pocket 2310 may be defined
within an interior wall surface of the swash collar 2003 facing an
exterior wall surface of the shaft 2001. Such hydrostatic pressure
pockets 2310 provide a moment on the swash collar 2003 that is
mostly equal and opposite to a piston moment load and that in
effect reduced loads carried by the swash collar support bearings
2399. Fluid pressure is supplied through shaft fluid passages 2121,
2131 (FIG. 19) in fluid cooperation with housing fluid passages
2720, 2730 that are connected to a fluid inlet and outlet of the
axial piston machine 2000. Use of the working fluid pressure to
counter act piston moment loads may increase the power capabilities
of the axial piston while reducing machine size and cost.
[0130] In embodiments, and referring to FIGS. 16-17, a seal 2311
may be disposed between the exterior wall surface of the shaft 2001
and the interior wall surface of the swash collar 2003 defining the
hydrostatic pressure pocket 2310 to provide a seal about the
hydrostatic pressure pocket 2310. The seal 2311 may be an o-ring or
other suitable sealing structure as understood by those of ordinary
skill in the art.
[0131] Further, referring to FIGS. 16 and 19, working fluid is
configured to flow through the shaft fluid passages 2121, 2131
(FIG. 19) to a respectively aligned hydrostatic pressure pocket
2310. By way of example and not limitation, in operation, working
fluid flows through a left-side shaft fluid passage 2131 as shown
in FIG. 19 to be received by a top left side hydrostatic pressure
pocket 2310 of FIGS. 16 and 27 and by an opposite, diagonally
disposed bottom right side hydrostatic pressure pocket 2310.
Similarly, working fluid flows through a right-side shaft fluid
passage 2121 as shown in FIG. 19 to be received by a top right side
hydrostatic pressure pocket 2310 of FIGS. 16 and 27 and by an
opposite, diagonally disposed bottom left side hydrostatic pressure
pocket 2310. The flow of the pressurized fluid between these pairs
of diagonally opposite hydrostatic pressure pockets 2310 cancels
respective bearing forces and creates a moment coupling to counter
moment on the wobble plate 2004. The moment on the wobble plate is
transferred to the swash collar 2003 through a set of wobble plate
support bearings 2499, for example, and is counteracted by the
moment created by the hydrostatic pressure pockets 2310 to balance
forces. Such balanced bearing forces allow the variable
displacement axial piston machine 2000 described herein, which
includes interface bearings to couple the wobble plate 2004, swash
collar 2003, and shaft 2001, to be utilized in high pressure, heavy
duty hydraulic systems, such as those capable of carrying loads
above a range of from about 3000 psi to 5000 psi.
[0132] In operation, as shown through various positions of the
axial machine set forth in FIGS. 20-25, the shaft 1 may rotate
either in a counter-clockwise direction 2180 (FIGS. 20-22) or in a
clockwise direction 2182 (FIGS. 23-25) to effect wobble plate 2004
tilt variation through the adjustable swash drive as the shaft 2001
rotates and a corresponding piston 6 reciprocation. Through such
variable displacement, torque and speed are transferred from the
rotating shaft 2001 to the wobble plate through such couplings as
described herein. An external motor may drive and provide torque
and speed to the shaft 2001. The shaft 2001 in turn drives the pin
2002, which drives the swash collar 2003. Tilt as variable
displacement of the swash collar 2003 is controlled by a swash
control mechanism, such as the control piston 2008 and bias spring
2009 assembly controlled by the flow control device 2799 as
described herein. Rotation and tilt of the swash collar 2003 drives
tilt of the wobble plate 2004, which wobble plate 2004 does not
rotate. Rather, the wobble plate 2004 is free to float and is
restricted from rotation by the piston 2006 that is contained
within respective piston bores defined within the housing 2007 of
the stationary cylinder block. Slippers 2005 are coupled to
respective pistons 2006 housed within the piston bores. The wobble
plate 2004 includes interior surfaces 2401 that are disposed about
slipper surfaces 2501 of each slipper 2005, and each slipper 2005
may rotate within and with respect to the wobble plate 2004 and in
alignment with rotation of the shaft 2001, for example. Thus, as
shown in FIGS. 24-25, during rotation, each slipper pin 2599
initially configured to face the same direction as the pin 2002
coupling the swash collar 2003 to the shaft 2001 may rotate in
alignment with the pin 2002 as the shaft 2001 rotates effecting a
corresponding rotation of the slippers 2005. Rotation of each
slipper 2005 effects a corresponding rotation of a respective
piston 2006 to which the slipper 2005 is attached through the
slipper pin 2599.
[0133] As one side of the wobble plate 4 tilts upward with respect
to a piston bore in which a piston 2006 is housed, the piston 2006
is driven upward into the piston bore as well. As the swash collar
rotates, the wobble plate 2004 will be drive to tilt downward with
respect to the piston bore in an opposite direction such that the
piston 2006 is driven downward with respect to the piston bore.
Referring to FIGS. 20-21, when the shaft 2001 rotates in a
counter-clockwise manner, the depicted left side of the wobble
plate 2004 first tilts upward while the opposite right side tilts
downward with respect to the piston bores such that the
corresponding pistons 2006 in each piston bore either are driven
upward on the left side or driven downward on the right side.
Referring to FIGS. 21-22, as the shaft 2001 continues to rotate in
the counter-clockwise manner, the left side of the wobble plate
2004 is driven downward and the right side is driven upward with
respect to the piston bores housing the pistons 2006. Corresponding
pistons 2006 in each piston bore thus are now driven downward on
the left side or driven upward on the right side. In such a manner,
the pistons 2006 reciprocate within their respective piston bores
as the shaft 2001 rotates counter-clockwise.
[0134] Referring to FIGS. 23-25, the shaft 2001 may rotate in a
clockwise manner effecting an opposite piston reciprocation pattern
than that depicted in FIGS. 20-22. FIG. 23 illustrates another
perspective, partially cross-sectional side view of the axial
piston machine 2000 in a first position; FIG. 24 shows the axis
piston machine in a second position; and FIG. 25 shows the axis
piston machine in a third position in a view that is similar to the
position shown in FIG. 14.
[0135] Referring to FIGS. 23-24, as the shaft 2001 rotates in a
clockwise manner, the depicted left side of the wobble plate 2004
first tilts downward while the opposite right side tilts upward
with respect to the piston bores such that the corresponding
pistons 2006 in each piston bore either are driven downward on the
left side or driven upward on the right side. Referring to FIGS.
24-25, as the shaft 2001 continues to rotate in the clockwise
manner, the left side of the wobble plate 2004 is driven upward and
the right side is driven downward with respect to the piston bores
housing the pistons 2006. Corresponding pistons 2006 in each piston
bore are now driven upward on the left side or driven downward on
the right side. In such a manner, the pistons 2006 reciprocate
within their respective piston bores as the shaft 2001 rotates
clockwise in an opposite manner to that described and shown in
FIGS. 20-22 in which the shaft 2001 rotates counter-clockwise. The
amount of upward and downward movement of the wobble plate 2004 is
controlled by the amount of fluid provided by the flow control
device 2799 to the piston chamber 2112 through shaft fluid passages
2110, 2111 to control the control piston 2008 and the bias spring
2009 to tilt the swash collar 2003 to a desired angle, which in
turn controls the tilt angle of the wobble plate 2004.
[0136] Referring to FIG. 26, a perspective view of the axial piston
machine 2000 similar to the second position shown in FIG. 21 is
depicted along with an effective piston force F.sub.PA.sub.eff
application to the plurality of pistons 2006. FIG. 27 illustrates a
schematic cross-sectional side view of the axial piston machine
2000 including moments and forces acting upon the axial piston
machine 2000 during operation.
[0137] As a non-limiting example, referring to FIG. 27, a moment
M.sub.399 of the swash collar support bearings 2399 is reduced by
an effective moment of the hydrostatic pressure pockets 2310 as
described above between the shaft 2001 and the swash collar 2003.
The hydrostatic pressure pockets 2310 are labeled in FIG. 27 as
including a first diagonally and opposed pair A and a second
diagonally and opposed pair B of hydrostatic pressure pockets 2310.
The first diagonally and opposed pair A of hydrostatic pressure
pockets 2310 are enacted upon by a force F.sub.310A during
operation, while the second diagonally and opposed pair B of
hydrostatic pressure pockets 2310 are enacted upon by a force
F.sub.310.sub.B during operation. A force F.sub.399 of the swash
collar bearings 2399 is shown in FIG. 27 as well. Ultimately, a
combination of the moment M.sub.399 of the swash collar support
bearings 2399 and the effective moment of the hydrostatic pressure
pockets 2310 carry and transfer a full piston moment M.sub.P.sub.A
between (i.e., from and to) the swash collar 2003 and the shaft
2001. Additionally, shaft support bearings 2199 and wobble plate
support bearings 2499 carry and transfer the full piston moment
M.sub.P.sub.A between the swash collar 2003 and the shaft 2001. As
torque is equivalent to a product of moment of inertia (i.e.,
rotational mass) and an angular acceleration, the full piston
moment M.sub.P.sub.A transferred to the shaft 2001 multiplied by an
angular acceleration value of the shaft 2001 would provide a shaft
torque value. In effect, with respect to the axial piston machine
2000 described herein, a resulting reduced shaft moment multiplied
by a resulting increased shaft rotational acceleration is able to
achieve a desired torque.
[0138] The axial piston machine 2000 described herein is a
reciprocating piston device utilizing variable displacement and
balanced bearing forces to enable operation in high pressure
hydraulic systems with a smaller structure, increased efficiency
and control, and reduced noise that can be realized through use of
the double-sided wobble plate drive mechanism. Such a double-sided
wobble plate drive mechanism as described herein provides for a
reduction in rotating mass (i.e., moment of inertia) leading to an
increased shaft rotational acceleration, a reduction in swash mass
leading to faster fluid displacement control, a compact design
leading to reduced material and use cost and a smaller envelope
size of the machine, a back-to-back piston configuration (i.e., a
double sided configuration) leading to a reduction in flow ripple,
noise, and friction, and a rotating swash collar assembly including
balanced loads leading to improved efficiency and reduced
structural noise transmitted to the housing through bearings.
Commercial uses for the axial piston machine 2000 include use as a
piston pump, motor, engine, or compressor. These often find
application in the drive and control industry on equipment. Such
equipment includes stationary industrial equipment and mobile
equipment such as vehicles, aircraft, ships, and the like.
[0139] Referring to at least FIGS. 28-39, axial piston devices as
described herein may include alternative embodiments for rotational
piston control and/or fluid displacement. With respect to FIGS.
28-30, an axial piston device 3000 including a rotatable piston
assembly 3088 configured for controlled rotation of a plurality of
pistons 3060 though a gear drive assembly 3140. Alternative drive
mechanisms configured to control rotation of a rotatable piston
with respect to a shaft of an axial piston device are contemplated
within the scope of this disclosure.
[0140] The gear drive assembly 3140 may include a shaft sun gear
3142 in communication with a plurality of piston planetary gears
3144. Each piston planetary gear 3144 is integrally or otherwise
coupled to a distal end of each piston 3060. As each piston
planetary gear 3144 is configured to drive rotation of each piston
3060, each piston 3060 is configured to rotate with respect to a
corresponding slipper assembly 3056, such as when the piston 3060
is coupled to the slipper assembly 3056 through a spherical joint
connection. The shaft sun gear 3142 is integrally or otherwise
coupled to a shaft 3001 of the axial piston device 3000. The gear
drive assembly 3140 is configured to control rotation of the shaft
3001 and the plurality of pistons 3060 while allowing for axial
relative motion in an axial direction therebetween. In an
embodiment, the plurality of piston planetary gears 3144 may
include an anti-rotation mechanism free to glide along the piston
3060 in the axial direction to eliminate the axial relative motion
between the shaft sun gear 3142 and the plurality of piston
planetary gears 3144. Such an anti-rotation mechanism may include,
for example, a ball bearing as an axial joint between a planetary
gear 3144 and a respective piston 3060 such that the planetary gear
3144 would not move relative to the shaft sun gear 3142. In
embodiments, as the shaft sun gear 3142 rotates about a shaft axis
3100 in a first direction W.sub.S, the plurality of piston
planetary gears 3144 rotate in a second direction W.sub.P opposite
the first direction about a bore axis of rotation 3601 of a
cylinder bore interface 3601 within which each piston 3060 is
housed. As a non-limiting example, the first direction may be one
of clockwise and counter-clockwise, and the second direction may be
the other of counter-clockwise and clockwise. When the shaft sun
gear 3142 rotates in a clockwise direction, the plurality of piston
planetary gears 3144 rotate in a counter-clockwise. Alternatively,
when the shaft sun gear 3142 rotates in a counter-clockwise
direction, the plurality of piston planetary gears 3144 rotate in a
clockwise direction. As the shaft sun gear 3142 rotates about the
shaft axis 3100 in the first direction W.sub.S, a swash mechanism
such as a wobble plate 3040 coupled to the shaft 3001 also rotates
about the shaft axis 3100 in the first direction W.sub.S generating
a rotational torque T.sub.W.
[0141] The wobble plate 3040 may be titled with respect to the
shaft axis 3100 of the shaft 3001 at a swash angle .alpha.. It is
contemplated within the scope of this disclosure that the axial
piston device 3000 may be a fixed or variable displacement machine.
Each piston 3060 interfaces with a proximal interface 3401 of the
wobble plate 3040 through the slipper assembly 3056. As the wobble
plate 3040 rotates, the plurality of pistons 3060 reciprocate
within and with respect to respective cylinder bore interfaces 3601
along respective bore axes of rotation 3608.
[0142] In embodiments, the rotatable piston assembly 3088 of the
axial piston device 3000 may include a rotatable piston valve
assembly 3090 such that each piston 3060 includes an integral valve
port 3602. The integral valve port 3602 may include a ribbed
structure configured to separate the integral valve port 3602 into
a plurality of sub-port openings, such as the four openings of each
integral valve port 3602 shown in FIGS. 28-39. The ribbed structure
may assist with increasing rigidity and durability of the integral
valve port 3602 of each piston 3060. Alternatively, as shown in
FIG. 30, the rotatable piston assembly 3088 of the axial piston
device 3000 may a plurality of pistons 3060 that do not include one
or more integral valve ports 3602 and rather may cooperate with a
separate rotary valve for fluid displacement within the axial
piston device 3000.
[0143] A proximal manifold port 3106 of the axial piston device
3000 is in communication with a proximal manifold passage 3104 that
is in communication with a plurality of openings that communicate
with an inward cylinder block port 3102 when respectively aligned
with the inward cylinder block port 3102. An outward cylinder block
port 3103 is in communication with a distal manifold passage 3105.
In operation as a pump, and referring to FIG. 29, fluid may enter
into a proximal manifold port 3106, proceed through the proximal
manifold passage 3104 and into the inward cylinder block port 3102.
Fluid may then flow into a piston 3060 when the piston 3060 has
rotated to an inward position such that the integral valve port
3602 of the piston 3060 is aligned with the inward cylinder block
port 3102. As the piston 3060 rotates to another, outward position
opposing the inward position, the integral valve port 3602 aligns
with the outward cylinder block port 3103 such that fluid proceeds
into the outward cylinder block port 3103 and continues on into the
distal manifold passage 3105. In operation as a motor, the fluid
direction may be reversed for receipt through the distal manifold
passage 3105 and the outward cylinder block port 3103 and flow,
through the integral valve port 3602 of the rotating piston 3060,
into the inward cylinder block port 3102 and out through the
proximal manifold port 3106.
[0144] The slipper assembly 3056 operates similarly to how
described above with respect to the slipper assembly 50 of the
axial piston device 100 as shown in FIG. 5, and the axial piston
device 3000 may include structural components similar to those
described for the axial piston device 100 and shown in FIG. 5 other
than the differences as described herein. As a non-limiting
example, the piston 3060 may include a lubrication port 3606 and
one or more hydrostatic pockets as described herein, and the
respectively joined slipper assembly 3056 may additionally be in
fluid communication with the lubrication port 3606 and include a
respective lubrication port and/or one or more hydrostatic pockets
as described herein. A distal interface 3501 of the slipper
assembly 3056 may communication with the proximal interface 3401 of
the wobble plate 3040. During operation, the distal interface 3501
of the slipper assembly 3056 and the proximal interface 3401 of the
wobble plate 3040 remain in parallel due to forces pushing against
the rotatable piston 3060 and the slipper assembly 3056 in a
direction toward the wobble plate 3040. Such forces are provided by
fluid and friction forces from the cylinder bore interface 3601 on
the rotatable piston 3060. Additionally, a large bearing 3901 may
be disposed around a distal end of the wobble plate 3040 and about
the shaft 3001, and a small bearing 902 is disposed as a shaft
support bearing about a distal end of the rotatable shaft 3001.
[0145] With respect to FIG. 31, an axial piston device 4000
including a rotatable piston valve assembly 4090 is configured for
controlled rotation of a plurality of pistons 4060 including
respective integral ports 4602 though a gear drive assembly 4140.
In alternative embodiments, the plurality of pistons 4060 may not
include respective integral ports 4602. The plurality of pistons
4060 with the integral ports 4602 rotate to fluidly communicate
between an inward cylinder block port 4102 and an outward cylinder
block port 4103 in a similar manner to the communication described
above and shown in FIG. 5 with respect to the axial piston device
100 of the valve port 602 with respect to the inward cylinder block
port 102 and an outward cylinder block port 103.
[0146] The gear drive assembly 4140 is directed to a gear mechanism
such as a floating gear 4145 disposed and communicating between a
wobble plate 4040 and a slipper assembly 4156. The slipper assembly
4156 includes a slipper interface ends 4501 that communicates with
and remain parallel to a proximal interface 4401 of the wobble
plate 4040 as the wobble plate 4040 rotates about a shaft axis 4100
at a swash angle of rotation. The slipper assembly 4156 includes a
slipper joint interface 4156, and each piston 4060 includes a
piston joint interface 4160. A connecting rod 4150 is disposed
between each piston 4060 and a respective slipper assembly 4156,
and constrained ends of the connecting rod 4150, which may define
revolute joints or otherwise constrained joints when coupled to
respective piston and slipper interfaces, are received and held
within and between the slipper joint interface 4156 and the piston
joint interface 4160. As the gear drive assembly 4140 is configured
to drive rotation of the slipper assembly 4156, a respectively
coupled piston 4060 is constrained with respect to the slipper
assembly 4156 as described herein to result in a corresponding
rotation. As a non-limiting example, rotation of the connecting rod
4150 in a first direction may force the piston 4060 to rotation in
an opposing direction. In alternative embodiments, the connecting
rod 4150 may include ends configured for a revolute joint fit or
otherwise constrained fit with respect to the slipper joint
interface 4156 and the piston joint interface 4160.
[0147] Use of an idler gear and radial motions effects rotation of
the floating gear 4145 to control rotation of the slipper assembly
4145. In an embodiment, the floating gear 4145 of the gear drive
assembly 4140 is fixed to the proximal surface 4401 of the wobble
plate 4040 and is configured to drive the slipper assembly 4056 in
a controlled rotation to, through the connecting rod 4150, effect a
controlled rotation of a respectively joined piston 4060 about a
bore axis of rotation 4608 of a cylinder bore interface 4601 within
which respective piston 4060 reciprocates. The gear drive assembly
4140 is configured to operate to control rotation of the plurality
of pistons 4060 at a positive swash angle with respect to the shaft
axis 4100, at a centered (zero) swash angle, or at an overcentered,
negative swash angle. Further, the gear drive assembly 4140 is
configured to operate to control rotation of the slipper assemblies
4056 within a groove interface of the wobble plate 4040 in which
each slipper assembly 4056 is housed. Such a groove interface may
be conical, cylindrical, circular, or planar, or other shape, each
shape configured to carry an axial or radial load. As a
non-limiting example, the shape of the groove interface is
configured to carry an axial load and carry a radial load such that
a corresponding radial joint maintains a position of the piston
4060 with respect to the wobble plate 4040. The radial surfaces of
the groove interface are thus configured to carry at least a
portion of an axial piston load as the wobble plate 4040 is tilted.
It is contemplated within the scope of this disclosure that any of
the gear drive assemblies as described herein are configured to be
able to carry such an axial load and a radial load.
[0148] Referring to FIGS. 32-33, an axial piston device 5000
includes an integrated dual port manifold assembly 5170 for
communication with at least a dual port rotatable piston 5060 in
contrast to the single port design of the axial piston device 100.
The axial piston device 100 of FIG. 5 illustrates a piston 60
including a single valve port 602 for communication with a pair of
circumferentially opposite cylinder ports as the inward cylinder
block port 102 and the outward cylinder block port 103. By
contrast, the axial piston device 5000 illustrates a piston 5060
including circumferentially opposed valve ports 5602A, 5602B (i.e.,
spaced about 180 degrees apart) and a manifold 5110 including a
pair of circumferentially aligned cylinder ports 5102A, 5105B. The
manifold 5110 includes a pair of manifold ports 5106A, 5106B. In
embodiments, the manifold ports 5106A, 5106B may be aligned but
axially offset and/or angled with respect to one another and a
cylinder bore interface axis 5608 of a cylinder bore interface 5601
defining a cylinder bore within which a respective piston 5060 is
disposed. The manifold port 5106A is in fluid communication with a
passage 5102 that is in fluid communication with each cylinder port
5102A. The manifold port 5106B is in fluid communication with a
passage 5105 that is in fluid communication with each cylinder port
5105B.
[0149] In an embodiment of operation, such as when the axial piston
device 5000 acts as a pump, fluid enters the manifold port 5106A
and the passage 5102 that is in fluid communication with each
cylinder port 5102A. As the piston 5060 moves out of the cylinder
bore defined by the cylinder bore interface 5601 axially along the
cylinder bore interface axis 5608, similar to as described with
respect to the axial piston device 100. As shown in FIG. 32, as the
piston 5060 rotates about the cylinder bore interface axis 5608 and
moves downward and out of the cylinder bore defined by the cylinder
bore interface 5601, fluid is pulled from the cylinder port 5102A
into the valve port 5602A while the valve port 5602B and the
cylinder port 5105A are sealed off from one another by a
piston-bore cylindrical interface. As the piston 5060 continues to
rotate down to a bottom dead center, both valve ports 5602A, 5602B
are temporarily closed off from both cylinder ports 5102A,
5105B.
[0150] As the piston 5060 continues to rotate, the piston 5060
moves into the cylinder bore defined by the cylinder bore interface
5601. As the piston 5060 rotates about the cylinder bore interface
axis 5608 and moves upward and into the cylinder bore defined by
the cylinder bore interface 5601, fluid is discharged from the
valve port 5602B of the piston 5060 and into the cylinder port
5105B. In such a position, the valve port 5602A of the piston 5060
and the cylinder port 5102A are sealed off from one another by the
piston-bore cylindrical interface. As the piston 5060 continues to
rotate up to a top dead center, both valve ports 5602A, 5602B are
temporarily closed off from both cylinder ports 5102A, 5105B. The
integrated dual port manifold assembly 5170 of the axial piston
device 5000 with the aligned, internal cylinder ports 5102A, 5105B
permits for a more compact manifold package that assists with
balancing side forces from cylinder port pressure without creating
a moment.
[0151] Referring to FIGS. 34-39, rotatable pistons as described
herein may include one or more hydrostatic pockets. With respect to
FIGS. 34-35 and 38, a single sided rotatable piston may include a
pair of circumferentially opposed hydrostatic pockets connected by
a common lubrication port and have forces acting upon the piston as
shown in FIG. 38 and described in greater detail below. With
respect to FIGS. 36-37 and 39, a double sided rotatable piston may
include two pairs of hydrostatic pockets, each pair including
aligned pockets connected by a common lubrication port and have
forces acting upon the piston as shown in FIG. 39 and described in
greater detail below.
[0152] Referring to FIGS. 34-35 and 38, a single sided rotatable
piston may include a pair of circumferentially opposed hydrostatic
pockets connected by a common lubrication port and have forces
acting upon the piston as shown in FIG. 38. The pair of hydrostatic
pockets are circumferentially disposed on a sidewall of the piston,
and the sidewall is disposed between the ends of the piston.
Referring to FIGS. 34-35, a rotatable piston assembly 6088 includes
a piston 6060 coupled to a slipper assembly 6050. The slipper
assembly 6050 includes a hydrostatic pocket 6505 in fluid
communication with a lubrication port 6506. The lubrication port
6506 is configured to fluidly communicate with a lubrication port
6606 of the piston 6060 as the piston 6060 and the slipper assembly
6050 as described herein similar to the constrained rotation of the
piston 60 and the slipper assembly 50 of the axial piston device
100 having a single sided piston configuration, as shown in FIG.
5.
[0153] The lubrication port 6606 is configured to axially extend
between ends of the piston and is in fluid communication with a
pair of hydrostatic pockets 6172 through a respective pair of
pocket lubrication ports 6174. By way of example and not as a
limitation, a pocket lubrication port 6174A is disposed between a
hydrostatic pocket 6172A and the lubrication port 6606 of the
piston 6060. Further, a pocket lubrication port 6174B is disposed
between a hydrostatic pocket 6172B and the lubrication port 6606 of
the piston 6060. The hydrostatic pocket 6172B is circumferentially
disposed about 180 degrees apart from the hydrostatic pocket 6172A
on the piston 6060. It is contemplated within the scope of these
disclosure that the pair of hydrostatic pockets may be of a similar
size or be different in size, where each size is dependent on a
geometry of the system to carry load. By way of example, and not as
a limitation, the hydrostatic pocket 6172B may be larger than the
hydrostatic pocket 6172A as the hydrostatic pocket 6172B is
configured to carry a load (2F) double the load the hydrostatic
pocket 6172A is configured to carry (F), as shown in FIGS. 34-35
and 38.
[0154] Referring to FIGS. 36-37 and 39, a double sided rotatable
piston may include two pairs of hydrostatic pockets 7172, each pair
including aligned pockets connected by a common lubrication port
and have forces acting upon the piston as shown in FIG. 39.
Referring to FIGS. 36-37, a rotatable piston assembly 7088
including a piston slipper assembly 7056, which includes a piston
7060 coupled to a slipper 7005 through a slipper pin 7599. The
slipper 7005 includes a pair of opposing slipper surfaces 1501, and
the piston slipper assembly 7056 operates with respect to a swash
mechanism similar to the piston slipper assembly 1056 as shown in
FIG. 12 and as described with respect to the axial piston device
1000 having a back to back, double-sided piston configuration.
[0155] A respective lubrication port of pair of lubrication ports
7606, 7067 is in fluid communication with a respective pair of
hydrostatic pockets 7172 through a respective pair of pocket
lubrication ports 7174. By way of example, and not as a limitation,
the hydrostatic pockets 7174 may be sized and disposed on the
piston 7060 dependent on a geometry of the system to carry load.
Each of the hydrostatic pockets 7174 is configured to carry a load
F/2 and are similarly sized with respect to the piston 7060
described herein. With respect to a traverse axis perpendicular to
an axial, longitudinal axis of the piston 7060, a pair of aligned
hydrostatic pockets 7172A and 7172B may be opposing aligned along
the traverse axis with or offset with respect to the traverse axis
from the pair of aligned hydrostatic pockets 7172C and 7172D
circumferentially disposed from the pair of aligned hydrostatic
pockets 7172A and 7172B on the piston 7060. A pocket lubrication
port 7174A is disposed between a hydrostatic pocket 7172A and the
lubrication port 7606 of the piston 7060, and a pocket lubrication
port 7174B is disposed between a hydrostatic pocket 7172B and the
lubrication port 7606 of the piston 7060. Further, a pocket
lubrication port 7174C is disposed between a hydrostatic pocket
6172C and the lubrication port 7607 of the piston 7060, and a
pocket lubrication port 7174D is disposed between a hydrostatic
pocket 7172D and the lubrication port 7607 of the piston 7060. The
hydrostatic pocket 7172A is in fluid communication with the
hydrostatic pocket 7172B through the lubrication port 7606, and the
hydrostatic pockets 7172A, 7172B are aligned on the piston 7060.
The hydrostatic pocket 7172C is in fluid communication with the
hydrostatic pocket 7172D through the lubrication port 7607, and the
hydrostatic pockets 7172C, 7172D are aligned on the piston 7060.
The hydrostatic pockets 7172A, 7172B are circumferentially disposed
about 180 degrees apart from the hydrostatic pockets 7172C, 7172D
on the piston 7060.
[0156] FIG. 38 illustrates forces acting upon the single sided
rotatable piston 6060 of FIGS. 34-35, and FIG. 39 illustrates
forces acting upon the double sided rotatable piston 7060 of FIGS.
36-37. With respect to FIG. 38, an axial piston load F.sub.P is
shown at a top of the piston 6060, a piston edge load F is shown at
an upper right piston edge, a load 2F disposed at an end of the
cylinder bore in which the piston 6060 is disposed is shown at an
intermediate left piston edge, and a radial load F equal to F.sub.P
tan .alpha. is shown at a bottom right piston edge. Alpha (.alpha.)
is the swash angle of a translational piston axis of the piston
6060 communicating with a swash mechanism of an axial piston
machine as described herein with respect to a longitudinal shaft
axis of rotation of a shaft about which a swash mechanism is
disposed and rotates. Placement of the load 2F is axially adjusting
with respect to the piston 6060 as the piston 6060 axially
translates within the cylinder bore. Summing the load 2F with the
piston edge load F results in a frictional force load F.sub.f of
3F.mu., where .mu. is a coefficient of friction. The hydrostatic
pockets 6172A, 6172B assist to balance the loads between the
opposing right and left sides of the piston 6060 and to increase
the mechanical efficiencies of the axial piston device by, for
example, 3-5%. As the position of the load 2F is estimated, the
piston 6060 may carry a moment and positioning of the hydrostatic
pocket 6172B may be placed at a position of the piston 6060
expected to align with the end of the cylinder bore to receive the
load 2F. The load 2F divided by the piston edge load F may be
dependent on an average of L and L/2 of the piston 6060, where L is
a piston length and L/2 is the estimated position of the load
2F.
[0157] With respect to FIG. 39, an axial piston load F.sub.P is
shown at a top of the piston 7060, a piston edge loads F/2 are
shown at an left piston ends, and a radial load F equal to F.sub.P
tan .alpha. is shown at an intermediate right piston edge. Alpha
(.alpha.) is the swash angle of a translational piston axis of the
piston 7060 communicating with a swash mechanism of an axial piston
machine as described herein with respect to a longitudinal shaft
axis of rotation of a shaft about which a swash mechanism is
disposed and rotates. As piston 7060 does not carry a moment, the
top and bottom positions of F/2 are known and the hydrostatic
pockets 7172 may be placed at such positions to carry the load and
balances the forces acting upon the piston 7060. Summing the loads
F/2 results in a frictional force load F.sub.f of F.mu., where .mu.
is a coefficient of friction. The hydrostatic pockets 7172A-7172D
thus assist to completely balance the loads between the opposing
right and left sides of the piston 7060 and to increase the
mechanical efficiencies of the axial piston device by, for example,
more than 3-5%. As the position of the load F is known and the
piston 7020 does not carry a moment, the load splits between the
top and bottom of the piston 7060 as F/2. Positioning of the
hydrostatic pockets 7172 may be placed at a positions of the piston
7060 predicted and known to align each load F/2. Further, an area
of the piston 7060 may be half the area of the piston 6060, and
frictional forces acting upon the piston 7060 may be a sixth of
those acting upon the piston 6060. Such reduced friction forces
acting on a piston interface may further remove load on the piston
and increase mechanical efficiencies of the piston in the axial
piston device. Advantages of both the piston 6060 and the piston
7060 may include increased efficiencies, durability, and
reliability of an associated axial piston device.
[0158] Referring to FIGS. 40-41, an axial piston device 8000 is
shown that includes a fixed angle rotatable piston 8060, a swash
mechanism 8040 of a fixed displacement assembly, a shaft 8001, a
shaft axis 8100, a cylinder block 8010, a cylinder bore interface
8601 defining a cylinder bore in which the fixed angled rotatable
piston 8060 is positioned, a large bearing 8902, and a small
bearing 8901. The large bearing 8902 supports the swash mechanism
8040 and a distal shaft portion of the shaft 8001 within the
cylindrical block 8010, and the small bearing 8902 supports a
proximal portion of the shaft 8001 within the cylindrical block
8010. The fixed angled rotatable piston 8060 includes an integral
valve port 8602 and a lubrication port 8606. Use of the fixed angle
rotatable piston 8060 in the axial piston device 8000 provides for
controlled rotation of the fixed angled rotatable piston 8060.
Rotation of the shaft 8001 effectives a corresponding rotation of
the swash mechanism 8040, which in turn effectives a translation
and rotation of the fixed angled rotatable piston 8060 within the
cylinder bore interface 8601. Such a fixed angled rotatable piston
8060 has an edge interface 8501 that includes an angle with respect
to a piston axis that matches an swash angle of the swash mechanism
8040 with respect to the shaft axis 8100. An edge interface 8501
rotates with respect to and against a proximal interface 8401 of
the swash mechanism 8040.
[0159] Referring to FIG. 42, a rotatable piston valve assembly 9090
includes a piston-slipper revolute joint for controlled rotation of
a piston 9060 within a cylinder bore of an axial piston machine, as
described herein. The piston 9060 is illustrated to include an
integral valve port 9062, though pistons without such an integral
valve port and that communicate with a separate valve for the
rotatable piston valve assembly 9090 is within the scope of this
disclosure. The rotatable piston valve assembly 9090 includes the
piston 9060 joined to a slipper assembly 9050 through a press fit
with respect a trunnion 9503. The trunnion 9053 includes a side
wall 9506 disposed between ends, an interface 9507, and an opening
9505 defined by the interface 9507 and the side wall 9506. The
slipper assembly 9050 includes a distal interface 9501 to rotate
against a proximal interface of a swash mechanism, a slipper 9058
extending from the distal interface 9501, a slipper neck 9504
extending from the slipper 9058, a slipper neck wall 9509, a top
neck interface 9502, and a top neck opening 9511, a side neck
interface 9510, and a side neck opening 9508. The top neck opening
9511 is defined by the slipper neck wall 9509 and the top neck
interface 9502. The side neck opening 9508 is defined by the
slipper neck wall 9502 and the side neck interface 9510.
[0160] Pins 9513 and 9514 are used to attach the trunnion 9503 to
the slipper assembly 9050 and to the piston 9060 to form a revolute
joint connection configured to control rotation of the piston 9060
within an axial piston device as described herein. The trunnion
9503 is received into the side neck opening 9508 of the slipper
neck 9504 such that the side wall 9506 communicates with the side
neck interface 9510 and the opening 9505 of the trunnion 9503 is
aligned with the top neck opening 9511. The connecting end 9512 is
received into the top neck opening 9511 of the slipper neck 9504
and the opening 9505 of the trunnion 9503 and communicates with the
top neck interface 9502 of the slipper neck 9504.
[0161] Referring to FIG. 43, a rotatable piston assembly 9188,
which may or may not include an integral valve, is shown as
including a piston 9180 attached to a slipper assembly 9184 a
constrained spherical socket 9190. The constrained spherical socket
9190 is in fluid communication with an interior of the piston
through a lubrication port 9182 and is constrained within the
slipper assembly 9184 with a pin 9192. The slipper assembly 9184
includes a distal interface 9194 to communicate and rotate against
a proximal interface of a swash mechanism of an axial piston device
as described herein. The distal interface 9194 may define a
lubrication port 9202 that is in fluid communication with the
lubrication port 9182 of the piston 9180. The slipper assembly 9184
further includes a slipper shoe 9186 proximally extending from the
distal interface 9194, and a slipper neck 9196. The slipper neck
9196 includes a neck interface 9189 configured to receive and
communicate with an interface 9200 of the constrained spherical
socket 9190.
[0162] One or more embodiments described herein are directed to
controlled rotation of a rotatable piston within a cylinder bore
and with respect to a swash mechanism of an axial piston device,
whether the device is a fixed displacement machine or a variable
displacement machine. Pistons configured for such controlled
rotation with respect to a swash mechanism may include a fixed
angle rotatable piston and a fixed angle swash mechanism, such as
the fixed angle rotatable piston 8060 and the swash mechanism 8040
of FIGS. 40-41. Other pistons configured for such controlled
rotation with respect to a swash mechanism may include a rotatable
piston assembly including a revolute joint between the piston and a
slipper assembly for a constrained rotation of the piston with
respect to the slipper assembly, such that rotation of the slipper
assembly effects a corresponding rotation of the piston due to the
revolute joint. Non-limiting examples of such revolute joint
rotatable piston assembly connections include a slipper ring
connection, a three-piece assembly connection (including a press
fit trunnion), a constrained spherical connection (including a
spherical socket with a pin), and a connecting rod (bent-axis)
connection. The slipper ring connection is shown with respect to at
least the single sided rotatable piston assemblies 88 including
piston 60 of the axial piston device 100 of FIGS. 1-9H. The
three-piece assembly connection including a press fit trunnion is
shown with respect to at least the slipper assembly 9050 as
attached to the piston 9060 of FIG. 42. The constrained spherical
connection including a spherical socket with a pin is shown with
respect to at least the rotatable piston assembly 9188 including
the slipper assembly 9184 attached to the piston 9180 of FIG. 43.
The connecting rod connection, with a bent-axis, is shown with
respect to at least the connecting rod 4150 disposed between the
piston 4060 and the respective slipper assembly 4146 of the axial
piston device 4000 of FIG. 31.
[0163] Yet other pistons configured for such controlled rotation
with respect to a swash mechanism may include a rotatable piston
assembly including alternative synchronized drive mechanisms such
as a shaft-piston gear drive assembly or a swash mechanism-slipper
gear drive assembly requiring an idler gear and radial motion.
Thus, rotation of the slipper assembly effects a corresponding
rotation of the piston due to the synchronized drive mechanisms.
Non-limiting examples of such synchronized drive mechanisms for a
shaft-piston gear drive assembly is shown with respect to at least
the rotatable piston assembly 3088 including the gear drive
assembly 3140 having a shaft sun gear 3142 in communication with a
plurality of piston planetary gears 3144 of the axial piston device
3000 of FIGS. 28-30. Non-limiting examples of such synchronized
drive mechanisms for a swash mechanism-slipper gear drive assembly
is shown with respect to at least the gear drive assembly 4140
including the floating gear 4145 disposed and communicating between
a wobble plate 4040 and a slipper assembly 4156 of the axial piston
device 4000 of FIG. 31.
[0164] Further pistons configured for such controlled rotation with
respect to a swash mechanism may include a rotatable piston
assembly including hydrostatic pockets to counteract swash
mechanism radial piston loads, such as for single sided or doubled
sided (back to back) piston configurations. Non-limiting examples
of single sided piston configurations including hydrostatic pockets
is shown FIGS. 34-35 and 38 with respect to at least the rotatable
piston assembly 6088 that includes the piston 6060 including a pair
of hydrostatic pockets 6172 and coupled to a slipper assembly 6050.
Non-limiting examples of double sided piston configurations
including hydrostatic pockets is shown FIGS. 36-37 and 39 with
respect to at least the rotatable piston assembly 7088 that
includes the piston 7060 including two pairs of hydrostatic pockets
7172, each pair aligned on the piston 7060, which is coupled to the
slipper 7005 through a slipper pin 7599.
[0165] Moreover, pistons configured for such controlled rotation
with respect to a swash mechanism may include a rotatable piston
valve assembly including a piston with an integral valve.
Non-limiting examples of such rotatable piston valve assemblies
include a single valve port in communication with two
circumferentially opposed cylinder ports on a piston end in a
single sided or double sided piston configuration, or a pair of
circumferentially opposed valve ports for communication with
circumferentially aligned cylinder ports. Non-limiting examples of
such rotatable piston valve assemblies including a single valve
port in communication with two circumferentially opposed cylinder
ports in a single sided piston configuration is shown FIGS. 1-9H
with respect to at least the piston 60 including the integral valve
port 602 for communication with and between the inward cylinder
block port 102 and the outward cylinder block port 103; is further
shown in FIG. 29 with respect to the axial piston device 3000
including the piston 3060 having the integral valve port 3602 for
communication with and between the inward cylinder block port 3102
and the outward cylinder block port 3103; and is further shown in
FIG. 40 with respect to the axial piston device 8000. Non-limiting
examples of such rotatable piston valve assemblies including a
single valve port in communication with two circumferentially
opposed cylinder ports in a double sided piston configuration, such
that each piston end includes a valve port, is shown FIGS. 10-13
with respect to at least the piston 1006 including the first and
second valve ports 1602A, 1602B circumferentially disposed at
opposing piston ends for communication with and between cylinder
ports 1702, 1703 on opposing ends of the axial piston device 1000.
Non-limiting examples of such rotatable piston valve assemblies
including a pair of circumferentially opposed valve ports for
communication with circumferentially aligned cylinder ports is
shown FIGS. 32-33 with respect to at least the piston 5060
including the integral valve ports 5602A, 5602B for communication
with respect to and between the pair of circumferentially aligned
cylinder ports 5102A, 5105B.
[0166] Such rotatable piston valve assemblies may be applied to
single sided or double sided piston configurations. Such double
sided piston configurations may be double ended pistons supported
by a wobble plate that is supported by back to back bearings that
transfer loads to a tilted swash collar and shaft to which the
swash collar is connected. Non-limiting examples of such rotatable
piston valve assemblies including a single sided piston
configuration is shown at least in FIGS. 1-9H with respect to at
least the plurality of pistons 60 of the axial piston device 100;
in FIGS. 28-30 with respect to at least the axial piston device
3000; and in FIG. 31 with respect to at least the axial piston
device 4000. Non-limiting examples of such rotatable piston valve
assemblies including a double sided piston configuration is shown
at least in FIGS. 10-13 with respect to at least the plurality of
pistons 1006 of the axial piston device 1000; and in FIGS. 14-27
with respect to at least the plurality of pistons 2006 of the axial
piston device 2000.
[0167] Pistons configured for such controlled rotation with respect
to a swash mechanism may further include a rotatable piston valve
assembly including a piston with an integral valve and with one or
more hydrostatic pockets. Non-limiting examples of such rotatable
piston valve assemblies include pistons including one or more
hydrostatic pockets, slipper assemblies including one or more
hydrostatic pockets, and/or one or more hydrostatic pockets in an
axial piston device such as in a cylinder bore. Such hydrostatic
pockets assist to counter act forces to due pressure in a piston
valve port and/or respective cylinder ports in fluid communication
with the rotatable piston valve assembly. Non-limiting examples of
such rotatable piston assemblies that may include pistons with
integral valves and that show pistons including one or more
hydrostatic pockets is shown FIGS. 34-37. Non-limiting examples of
such rotatable piston valve assemblies including slipper assemblies
including one or more hydrostatic pockets is shown at least FIGS. 5
and 8A-9H of the piston 60 of the axial piston device 100; and in
FIGS. 34-35. Non-limiting examples of one or more hydrostatic
pockets in an axial piston device is shown in FIGS. 16, 17, and 27
with respect to at least the hydrostatic pressure pockets 2310
included at an interface of the swash collar 2003 and the shaft
2001 of the axial piston device 2000.
[0168] Pistons configured for such controlled rotation with respect
to a swash mechanism may include a fixed displacement swash
mechanism at a fixed swash angle with respect to a shaft axis of
rotation as the axial piston device rotates for a fixed
displacement assembly or a variable displacement swash mechanism
configured for a variable swash angle with respect to a shaft axis
of rotation as the axial piston device rotates for a variable
displacement assembly. Non-limiting examples of such fixed
displacement assemblies is shown in at least FIGS. 10-13 with
respect to the axial piston device 1000 and in FIG. 40 with respect
to the axial piston device 8000. Non-limiting examples of such
variable displacement assemblies is shown in at least FIGS. 14-27
with respect to at least the axial piston device 2000.
[0169] The controlled rotation of a rotatable piston within a
cylinder bore and with respect to a swash mechanism of an axial
piston device as described herein permits a rotatable piston to
maintain a dynamic velocity, such that a piston reaching the end of
its stroke in a respective cylinder bore housing the piston does
not have a static velocity that goes to zero and rather maintains a
relative velocity between the piston and cylinder. As load carrying
capacity of a fluid film is dependent on relative motion of mating
surfaces of fluid film interfaces, maintaining such a dynamic,
relative velocity of the rotatable piston with respect to the
cylinder allows for dynamic pressure built in the fluid film and a
maintained load carrying capacity and ability while reducing and
generally eliminating a likelihood of metal contact between the
piston and the cylinder bore at the piston-cylinder interface that
may otherwise occur at a static, zero velocity at the
piston-cylinder interface. As a non-limiting example, such a
rotatable piston assembly maintaining a dynamic velocity is
beneficial at low speed conditions where such stick-slip phenomena
is more likely than high speed conditions to prevent such metal
contact at the piston-cylinder interface. Further, maintaining such
a dynamic, relative velocity at the piston-cylinder interface
allows for a reduction in piston friction forces as described
herein to positive increase and affect performance, reliability,
and durability of an associated axial piston device.
[0170] The rotatable piston assemblies as described herein
configured to lock and control a rotation of a piston, or a piston
and an attached slipper, such that rotation of the piston is
controlled with respect to rotation of the drive shaft of the axial
piston device. An addition of one or more hydrostatic pockets to a
cylinder interface of the piston may further improve performance,
reliability, and durability of an associated axial piston device.
Such hydrostatic pockets may be fed with pressurized fluid from a
piston working chamber and are configured to generate an equal and
opposite force to balance the piston radial forces. Such piston
radial forces are the radial piston forces induced by an
interaction between the piston and an associated angled swash
mechanism such as a swash plate as described herein. Addition of
one or more hydrostatic pockets to the piston thus aids to balance
the radial piston forces of the angled swash plate. Such balancing
of radial forces improves the performance, reliability, and
durability of the piston-cylinder interface and improves the
efficiency characteristics of the associated axial piston device.
Such rotatable piston assemblies as described herein are configured
for and as axial piston devices including, but not limited to, a
reciprocating piston machine having fixed and/or variable
displacement, a stationary cylinder block and/or rotating cylinder
block, and a radial and/or an axial piston reciprocating
machine.
[0171] Item 1. A rotatable piston valve assembly for a
reciprocating piston type hydraulic machine includes a rotatable
piston configured for a controlled rotation and configured to
reciprocate within a cylinder bore of the reciprocating piston type
hydraulic machine.
[0172] Item 2. The rotatable piston valve assembly of item 1, the
rotatable piston including a valve passage including an opening
disposed at a proximal end of the rotatable piston.
[0173] Item 3. The rotatable piston valve assembly of item 2, the
rotatable piston including an integral valve port in fluid
communication with the valve passage, the integral valve port
configured to provide a passage for fluid flow in one of a first
direction and a second direction opposite the first direction to
respectively act as one of a pump and a motor.
[0174] Item 4. The rotatable piston valve assembly of any of items
1 to 3, the rotatable piston including a piston revolute joint
interface disposed at a distal end of the rotatable piston and a
slipper assembly. The slipper assembly including a slipper shoe
comprising a distal interface configured to be disposed against a
proximal interface of a swashplate, the rotatable piston configured
for a controlled rotation with respect to the swashplate, a slipper
neck proximally extending from the slipper shoe, and a slipper
revolute joint comprising a slipper revolute joint interface
configured to be received by the piston revolute joint
interface.
[0175] Item 5. The rotatable piston valve assembly of item 4,
wherein the slipper assembly further includes a slipper ring
configured to be disposed around the slipper neck to maintain a fit
between the piston revolute joint interface and the slipper
revolute joint interface.
[0176] Item 6. The rotatable piston valve assembly of item 4,
wherein the slipper assembly further includes a hydrostatic pocket
defined by the distal interface, and a lubrication port in fluid
communication with the hydrostatic pocket.
[0177] Item 7. The rotatable piston valve assembly of item 6,
wherein the rotatable piston further includes a lubrication port in
fluid communication with the valve passage, and the lubrication
port of the rotatable piston is in fluid communication with the
lubrication port of the slipper assembly.
[0178] Item 8. The rotatable piston valve assembly of any of items
2 to 7, wherein the reciprocating piston type hydraulic machine is
an axial piston machine comprising the swashplate configured for
rotation and a stationary cylinder block.
[0179] Item 9. The rotatable piston valve assembly of item 1,
wherein the reciprocating piston type hydraulic machine is an axial
piston machine comprising a swashplate configured for rotation and
a stationary cylinder block.
[0180] Item 9. The rotatable piston valve assembly of any of items
8 to 9, wherein the axial piston machine includes a manifold
disposed within the stationary cylinder block and a swash housing,
the manifold configured for fluid communication with the rotatable
piston valve assembly. The manifold includes a proximal manifold
port disposed at a proximal end of the manifold within the
stationary cylinder block, and a proximal manifold passage in fluid
communication with the proximal manifold port and comprising a
plurality of proximal manifold passage port openings. The manifold
further includes a distal manifold port disposed along a side wall
of the manifold in the swash housing distal to the proximal end of
the manifold, and a distal manifold passage in fluid communication
with the distal manifold port and comprising a distal manifold
passage port opening. The manifold further includes an inward
cylinder block port disposed in the stationary cylinder block and
in fluid communication with one of the plurality of proximal
manifold passage port openings, and an outward cylinder block port
in fluid communication with the distal manifold passage port
opening.
[0181] Item 10. The rotatable piston valve assembly of item 9, the
rotatable piston valve assembly further including a plurality of
pistons, a plurality of slipper assemblies, and a plurality of
outward cylinder block ports, each slipper assembly coupled to a
respective piston, and each piston including an integral valve
port. Each piston abuts one of the inward cylinder block ports in
fluid communication with one of the plurality of proximal manifold
passage port openings of the proximal manifold passage, and each
piston abuts one of the plurality of outward cylinder block ports
that are in fluid communication with the distal manifold
passage.
[0182] Item 11. The rotatable piston valve assembly of item 1,
wherein the reciprocating piston type hydraulic machine is an axial
piston machine comprising a rotating swashplate, a stationary
cylinder block, and a rotatable shaft coupled to the rotating
swashplate.
[0183] Item 12. The rotatable piston valve assembly of item 11,
wherein rotation of the rotatable shaft is configured to rotate the
rotating swashplate, and rotation of the rotating swashplate is
configured control a rotation of the rotatable piston during
reciprocation of the rotatable piston in the cylinder bore.
[0184] Item 13. The rotatable piston valve assembly of item 12,
wherein rotation of the rotating swashplate is configured control a
rotation of the rotatable piston through a slipper assembly. The
slipper assembly further includes a slipper shoe comprising a
distal interface configured to be disposed against a proximal
interface of the rotating swashplate, the rotatable piston
configured for a controlled rotation with respect to the rotating
swashplate, a slipper neck proximally extending from the slipper
shoe, and a slipper revolute joint comprising a slipper revolute
joint interface configured to be received by a piston revolute
joint interface disposed at a distal end of the rotatable
piston.
[0185] Item 14. The rotatable piston valve assembly of item 13, the
rotatable piston valve assembly further including a hold down plate
configured to interface with the slipper assembly and apply a force
to maintain the slipper assembly against the rotating
swashplate.
[0186] Item 15. A method for using an axial piston machine as a
pump and a motor, the axial piston machine including a rotating
swashplate, a stationary cylinder block, and a rotatable shaft
coupled to the rotating swashplate is described. The method
includes reciprocating a rotatable piston of a rotatable piston
valve assembly in a cylinder bore of the stationary cylinder block
of the axial piston machine, the rotatable piston including an
integral valve port configured to provide a passage for fluid flow
in one of a pump direction and a motor direction opposite the pump
direction to respectively act as one of the pump and the motor. The
method further includes rotating the rotatable piston in the
cylinder bore during reciprocation, and controlling rotation of the
rotatable piston in the cylinder bore through a rotational control
assembly.
[0187] Item 16. The method of item 15, wherein the rotational
control assembly includes a plurality of rotatable pistons and a
plurality of slipper assemblies, each slipper assembly joined with
a rotatable piston through a revolute joint connection, and each
slipper assembly disposed against an interface of the rotating
swashplate, wherein rotation of the rotating swashplate is
configured to rotate the rotational control assembly. The method
further includes rotating the rotatable shaft about a shaft axis of
rotation to rotate the rotating swashplate about the shaft axis of
rotation, rotating the plurality of slipper assemblies of the
rotatable piston valve assembly through rotation of the rotating
swashplate, and rotating the plurality of rotatable pistons about a
bore axis of rotation through rotation of the plurality of slipper
assemblies respectively joined to the plurality of rotatable
pistons through respective revolute joint connections.
[0188] Item 17. The method of item 16, wherein a proximal interface
of the rotating swashplate is configured to adjust an adjustable
angle with respect to the shaft axis of rotation as the rotatable
shaft rotates.
[0189] Item 18. The method of item 16, wherein the axial piston
machine includes a manifold disposed within the stationary cylinder
block and a swash housing. The method further includes receiving
fluid in the pump direction flowing from a proximal end of the
manifold toward a distal side portion of the manifold into a
proximal manifold port disposed at the proximal end of the manifold
within the stationary cylinder block; receiving fluid into a
proximal manifold passage from the proximal manifold port;
receiving fluid into a plurality of inward cylinder block ports
disposed in the stationary cylinder block through respective
openings of the proximal manifold passage; when the integral valve
port of a rotatable piston of the plurality of rotatable pistons is
in fluid communication with a respective inward cylinder block
port, receiving fluid into the integral valve port to flow into a
valve passage of the rotatable piston; when the integral valve port
of the rotatable piston is in fluid communication with a respective
outward cylinder block port of a plurality of outward cylinder
block ports disposed in the stationary cylinder block, directing
fluid from the valve passage to flow through the integral valve
port and into the respective outward cylinder block port; receiving
fluid into a distal manifold passage in fluid communication with
the plurality of outward cylinder block ports; and discharging
fluid from a distal manifold port in fluid communication with the
distal manifold passage.
[0190] Item 19. The method of item 18, when flow of fluid is in the
pump direction, the method further including rotating the rotatable
shaft to rotate the rotating swashplate to rotate the rotatable
piston valve assembly, and converting mechanical energy from
rotating the rotatable shaft to hydraulic energy from the flow of
fluid in the pump direction.
[0191] Item 20. The method of item 19, the method further including
driving the rotatable shaft by an external torque at a rotational
speed, and directly transferring the external torque and the
rotational speed to the rotating swashplate.
[0192] Item 21. The method of item 16, wherein the axial piston
machine includes a manifold disposed within the stationary cylinder
block and a swash housing, the method further including receiving
fluid in the motor direction flowing from a distal side portion of
the manifold toward a proximal end of the manifold into a distal
manifold port of the manifold; receiving fluid into a distal
manifold passage from the distal manifold port, the distal manifold
passage in fluid communication with the distal manifold port and a
plurality of outward cylinder block ports disposed in the
stationary cylinder block; when the integral valve port of a
rotatable piston of the plurality of rotatable pistons is in fluid
communication with a respective outward cylinder block port of a
plurality of outward cylinder block ports, receiving fluid into the
integral valve port from the distal manifold passage and the
respective outward cylinder block port and into a valve passage of
the rotatable piston through the integral valve port; when the
integral valve port of the rotatable piston is in fluid
communication with a respective inward cylinder block port of a
plurality of inward cylinder block ports disposed in the stationary
cylinder block, receiving fluid into the respective inward cylinder
block port from the integral valve port; receiving fluid into a
respective opening of a plurality of openings of a proximal
manifold passage, the plurality of openings of the proximal
manifold passage in respective fluid communication with the
plurality of inward cylinder block ports; receiving fluid into the
proximal manifold passage from the respective opening of the
proximal manifold passage; receiving fluid into a proximal manifold
port from the proximal manifold passage, the proximal manifold port
disposed at a proximal end of the manifold within the stationary
cylinder block; and discharging fluid from the proximal manifold
port.
[0193] Item 22. The method of item 21, when flow of fluid is in the
motor direction, the method further including translating the
rotatable piston valve assembly into the rotating swashplate to
rotate the rotating swashplate to rotate the rotatable shaft, and
converting hydraulic energy from the flow of fluid in the motor
direction to mechanical energy from rotation of the rotatable
shaft.
[0194] For the purposes of describing and defining the present
disclosure, it is noted that reference herein to a variable being a
"function" of a parameter or another variable is not intended to
denote that the variable is exclusively a function of the listed
parameter or variable. Rather, reference herein to a variable that
is a "function" of a listed parameter is intended to be open ended
such that the variable may be a function of a single parameter or a
plurality of parameters.
[0195] It is also noted that recitations herein of "at least one"
component, element, etc., should not be used to create an inference
that the alternative use of the articles "a" or "an" should be
limited to a single component, element, etc.
[0196] It is noted that recitations herein of a component of the
present disclosure being "configured" in a particular way, to
embody a particular property, or to function in a particular
manner, are structural recitations, as opposed to recitations of
intended use. More specifically, the references herein to the
manner in which a component is "configured" denotes an existing
physical condition of the component and, as such, is to be taken as
a definite recitation of the structural characteristics of the
component.
[0197] For the purposes of describing and defining the present
disclosure it is noted that the terms "substantially" and
"approximately" are utilized herein to represent the inherent
degree of uncertainty that may be attributed to any quantitative
comparison, value, measurement, or other representation. The terms
"substantially" and "approximately" are also utilized herein to
represent the degree by which a quantitative representation may
vary from a stated reference without resulting in a change in the
basic function of the subject matter at issue.
[0198] Having described the subject matter of the present
disclosure in detail and by reference to specific embodiments
thereof, it is noted that the various details disclosed herein
should not be taken to imply that these details relate to elements
that are essential components of the various embodiments described
herein, even in cases where a particular element is illustrated in
each of the drawings that accompany the present description.
Further, it will be apparent that modifications and variations are
possible without departing from the scope of the present
disclosure, including, but not limited to, embodiments defined in
the appended claims. More specifically, although some aspects of
the present disclosure are identified herein as preferred or
particularly advantageous, it is contemplated that the present
disclosure is not necessarily limited to these aspects.
[0199] It is noted that one or more of the following claims utilize
the term "wherein" as a transitional phrase. For the purposes of
defining the present disclosure, it is noted that this term is
introduced in the claims as an open-ended transitional phrase that
is used to introduce a recitation of a series of characteristics of
the structure and should be interpreted in like manner as the more
commonly used open-ended preamble term "comprising."
* * * * *