U.S. patent application number 09/994158 was filed with the patent office on 2003-05-29 for compact pump or motor with internal swash plate.
Invention is credited to Hajek, Thomas J. JR., Smith, David P..
Application Number | 20030099551 09/994158 |
Document ID | / |
Family ID | 25540346 |
Filed Date | 2003-05-29 |
United States Patent
Application |
20030099551 |
Kind Code |
A1 |
Hajek, Thomas J. JR. ; et
al. |
May 29, 2003 |
COMPACT PUMP OR MOTOR WITH INTERNAL SWASH PLATE
Abstract
A fluid translating device is provided that includes a first
member having fluid inlet/outlet ports and a second member having a
plurality of pistons disposed therein secured to a stationary
central shaft. A camplate and port plate is disposed in the fluid
translating device about the stationary central shaft and located
between the first and second members. The camplate is in
communication with the fluid inlet/outlet ports and the plurality
of pistons is in mating contact with the port plate. An outer
input/output member is secured about the camplate and is rotatably
disposed about the first and second members to form a compact
arrangement.
Inventors: |
Hajek, Thomas J. JR.;
(Lockport, IL) ; Smith, David P.; (Joliet,
IL) |
Correspondence
Address: |
CATERPILLAR INC.
100 N.E. ADAMS STREET
PATENT DEPT.
PEORIA
IL
616296490
|
Family ID: |
25540346 |
Appl. No.: |
09/994158 |
Filed: |
November 26, 2001 |
Current U.S.
Class: |
417/269 |
Current CPC
Class: |
F03C 1/0615 20130101;
F04B 1/124 20130101; F03C 1/0631 20130101; F04B 1/148 20130101;
F04B 1/146 20130101; F03C 1/0605 20130101 |
Class at
Publication: |
417/269 |
International
Class: |
F04B 001/12 |
Claims
What is claimed is:
1. A fluid translating device, comprising: a stationary central
shaft having first and second end portions and a center portion
with a reference axis extending through the first, second, and
center portions; a first member securely connected to the first end
portion of the stationary central shaft about the reference axis
and having an end face and first and second inlet/outlet ports in
communication with the end face thereof; a second member securely
connected to the second end portion of the stationary central shaft
about the reference axis and having a face surface and a plurality
of equally spaced blind bores defined therein about the reference
axis and extending from the face surface thereof parallel to the
reference axis; a camplate rotatably disposed about the reference
axis of the stationary central shaft between the first and second
members and having a first end face portion in abutting contact
with the end face of the first member and a second end face portion
angled with respect to the reference axis and having a recess
defined therein, a face surface is disposed in the recess and the
face surface therein is in communication with the first end face
portion thereof; a port plate having a bearing assembly disposed
thereabout and being located within the recess of the camplate, the
port plate has first and second opposed faces and a plurality of
equally spaced formed cavities defined therein about the reference
axis between the first and second opposed faces and disposed with
the first opposed face thereof being in mating contact with the
face surface of the recess in the camplate; a plurality of pistons
with each piston thereof having first and second end portions with
the first end portion being slideably disposed within the
respective blind bores of the second member to define pressure
chambers therein and the second end portion thereof being in
contact with the other opposed face of the port plate; and an outer
input/output member disposed about the camplate and the first and
second members, the outer input/output member being secured to the
camplate and rotatable about the first and second members.
2. The fluid translating device of claim 1 wherein the end face of
the first member has first and second spaced apart circular grooves
defined therein about the reference axis and the first and second
spaced apart circular grooves are in communication with respective
ones of the first and second inlet/outlet ports and the first end
face portion of the camplate has first and second spaced apart
circular grooves defined therein about the reference axis and
located in contact with the end face of the first member and
adjacent to the respective ones of the first and second circular
grooves of the end face of the first member.
3. The fluid translating device of claim 1 wherein the face surface
of the second end portion of the camplate has a first arcuate
groove extending about the reference axis at a predetermined
distance and in communication with the first circular groove of the
first end face portion thereof and a second arcuate groove
extending about the reference axis at the same predetermined
distance of the first arcuate groove and in communication with the
second circular groove of the first end face portion thereof.
4. The fluid translating device of claim 3 wherein the first
arcuate groove extends an arcuate distance less than 180 degrees
and is disposed on one side of the end face thereof.
5. The fluid translating device of claim 4 wherein the second
arcuate groove extends an arcuate distance less than 180 degrees
and is disposed on the opposed side of the end face thereof.
6. The fluid translating device of claim 5 wherein the plurality of
formed cavities in the port plate are disposed at a distance from
the reference axis substantially the same as the predetermined
distance of the first and second arcuate grooves in the second end
portion of the camplate.
7. The fluid translating device of claim 6 including a first seal
and bearing arrangement disposed between the first member and the
input/output member and a second seal and bearing arrangement
disposed between the second member and the input/output member.
8. The fluid translating device of claim 7 wherein the fluid
translating device is a fluid motor.
9. The fluid translating device of claim 7 wherein the fluid
translating device is a fluid pump.
10. The fluid translating device of claim 1 wherein the end face of
the first member is perpendicular to the reference axis and the
second opposed face of the port plate forms an acute angle with
respect to the end face of the first member in the range of 10 to
35 degrees.
11. The fluid translating device of claim 10 wherein the acute
angle is 25 degrees.
12. The fluid translating device of claim 1 wherein each piston of
the plurality of pistons is a unitary member and has a reference
piston axis defined therein extending longitudinally through the
first and second end portions with a perpendicular reference piston
plane defined at one end thereof.
13. The fluid translating device of claim 12 wherein the second end
portion of each piston is enlarged and has a piston face surface
angled with respect to the axis of the piston and operative to abut
the second opposed face of the port plate at the predetermined
distance from the reference axis of the stationary central
shaft.
14. The fluid translating device of claim 13 wherein the piston
face surface of each piston forms an angle with respect to the
reference piston plane of the piston that is greater than the angle
formed by the second opposed end face of the port plate and the
reference plane of the stationary central shaft.
15. The fluid translating device of claim 14 wherein the angle
formed between the piston face surface of each piston and the
reference piston plane is approximately one half degree greater
than the angle formed between the second opposed surface of the
port plate and the reference plane of the stationary central
shaft.
16. The fluid translating device of claim 15 wherein a cavity is
defined through each piston along the reference piston axis
thereof.
17. The fluid translating device of claim 16 wherein the first end
portion of each piston has a peripheral surface and a force
balancing slot is defined in a portion of the peripheral surface at
a location generally opposed to the piston face surface of the
second end portion and near the end of the first end portion
thereof.
18. The fluid translating device of claim 17 wherein the force
balancing slot extends parallel to the reference axis thereof and
is wider at a location furthest from the end of the first end
portion.
19. The fluid translating device of claim 17 wherein the force
balancing slot is in fluid communication through an orifice with
the respective pressure chamber formed in the blind bore.
20. A fluid translating device adapted for use in a fluid system,
comprising: a stationary central shaft having first and second end
portions and a center portion with a reference axis defined therein
extending through the first, second, and center portions and a
reference plane defined therein perpendicular to the reference axis
thereof; a first member securely connected to the first end portion
of the stationary central shaft about the reference axis and having
an end face with first and second spaced apart circular grooves
defined therein about the reference axis and first and second
inlet/outlet ports connected to respective ones of the first and
second circular grooves; a second member securely connected to the
second end portion of the stationary central shaft about the
reference axis and having an end face and a plurality of bores
defined therein extending parallel to the reference axis and
disposed equally spaced from each other, each bore of the plurality
of pistons has a bottom surface at a predetermined distance from
the end face of the second member; a camplate rotatably disposed
about the reference axis of the stationary central shaft between
the first and second members, the camplate has a first end face
portion with first and second spaced apart circular grooves defined
therein about the reference axis and located in contact with the
end face of the first member and adjacent to the respective ones of
the first and second circular grooves of the end face of the first
member and a second end face portion angled with respect to the
first end face portion and to the reference axis, the second end
face portion has a face surface disposed in a recess with a first
arcuate groove extending about the reference axis at a
predetermined distance and in communication with the first circular
groove of the first end face portion thereof and a second arcuate
groove extending about the reference axis at the same predetermined
distance of the first arcuate groove and in communication with the
second circular groove of the first end face portion thereof; a
port plate having opposed faces and a bearing assembly disposed
thereabout and being located in the recess of the camplate, the
port plate has a plurality of spaced apart formed cavities defined
therethrough about the reference axis at the same predetermined
distance of the first and second arcuate grooves and is disposed in
the recess of the camplate in abutting contact with the face
surface in the recess; a plurality of pistons, each piston of the
plurality of pistons having a first end portion, a second end
portion and a reference piston axis, the second end portion of each
piston is enlarged and has a piston face surface that is in mating
contact with the port plate at the predetermined distance from the
reference axis of the stationary central shaft and the first and
second end portions of each piston has a cavity extending
therethrough parallel to the reference piston axis of the
respective piston and the first end portion thereof is slideably
disposed in the respective bores within the second end member to
define a chamber between the first end portion of the piston and
the bottom surface of the respective bores; a hold down mechanism
is secured to the port plate and operative to hold the plurality of
pistons in intimate contact with the port plate; and an outer
input/output member is disposed about and secured to the camplate
and is rotatably disposed about the first and second members.
21. The fluid translating device of claim 20 wherein a
perpendicular reference piston plane is defined at one end of each
piston and the piston face surface of each piston of the plurality
of pistons forms an angle with the reference piston plane that is
greater than the angle formed by one of the opposed faces of the
port plate and the reference plane of the stationary central
shaft.
22. The fluid translating device of claim 21 wherein the angle
between the piston face surface of each piston and the reference
piston plane is approximately one half degree larger than the angle
formed by the one opposed face of the port plate and the reference
plane of the stationary central shaft.
23. The fluid translating device of claim 22 wherein the first end
portion of each piston has a peripheral surface and a force
balancing slot is defined in the peripheral surface thereof at a
location near the end thereof opposed to the second end
portion.
24. The fluid translating device of claim 23 in combination with a
fluid system having a power source, a working element and a fluid
source.
25. The fluid translating device of claim 24 wherein the fluid
translating device is a fluid motor and the input/output member is
drivingly connected to the working element and the first
inlet/outlet port is connected to the fluid source.
26. The fluid translating device of claim 24 wherein the fluid
translating device is a fluid pump and the input/output member is
connected to and driven by the power source and the second
inlet/outlet port is connected to the working member.
Description
TECHNICAL FIELD
[0001] This invention relates generally to fluid translating units
and more particularly to a compact fluid translating device and the
use thereof in a fluid system.
BACKGROUND
[0002] Fluid translating units are well known in the art. They may
be designed to function as a fluid pump or a fluid motor.
Typically, in the axial piston units, they have a stationary
housing having a fluid inlet port, a fluid outlet port, an internal
rotating unit connected to an input/output shaft, a cam/swash plate
and internal porting to meter the fluid flow therethrough. The
rotating unit normally includes a rotating barrel having a
plurality of piston assemblies slideably disposed therein in
contact with the cam/swash plate. Due to the outer stationary
housing, these known fluid translating units are normally somewhat
bulky and require additional space when space may be very limited.
Additionally, the known axial fluid translating units are limited,
based at least in part on the piston assemblies, in their angular
displacement. In many of the known designs, the input/output shaft
is cantilevered and loads applied thereto tend to cause premature
bearing failures. There are some fluid translating motors that
rotate the outer portion of the motor at the same time that the
translating unit is being rotated. These arrangements require, in
most cases, the use of radial fluid translating units and have
additional length due to the output shaft extending from both ends.
One such example is set forth in U.S. Pat. No. 5,396,768 issued to
Joshua Zulu on Mar. 14, 1995.
[0003] The present invention is directed to overcoming one or more
of the problems set forth above.
SUMMARY OF THE INVENTION
[0004] In one aspect of the present invention, a fluid translating
device is provided and comprises a stationary central shaft, first
and second members, a camplate, a port plate, a plurality of
pistons, and an outer input/output member. The stationary central
shaft has first and second end portions and a center portion with a
reference axis extending through the first, second, and center
portions. The first member is securely connected to the first end
portion of the stationary central shaft about the reference axis
and has an end face and first and second inlet/outlet ports in
communication with the end face thereof. The second member is
securely connected to the second end portion of the stationary
central shaft about the reference axis and has a face surface and a
plurality of equally spaced blind bores defined therein about the
reference axis and the plurality of blind bores extends from the
face surface thereof parallel to the reference axis. The camplate
is rotatably disposed about the reference axis of the stationary
central shaft between the first and second members and has a first
end face portion in abutting contact with the end face of the first
member and a second end face portion angled with respect to the
reference axis and has a recess defined therein. A face surface is
disposed in the recess and the face surface therein is in
communication with the first end face portion thereof. The port
plate has a bearing assembly disposed thereabout and is located
within the recess of the camplate. The port plate has first and
second opposed faces and a plurality of equally spaced formed
cavities defined therein about the reference axis between the first
and second opposed faces. The port plate is positioned with the
first opposed face thereof being in mating contact with the face
surface of the recess in the camplate. Each piston of the plurality
of pistons has first and second end portions with the first end
portion being slideably disposed within the respective blind bores
of the second member to define pressure chambers therein and the
second end portion thereof is in contact with the other opposed
face of the port plate. The outer input/output member is disposed
about the camplate and the first and second members and the outer
input/output member is secured to the camplate and rotatable about
the first and second members.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a partial diagrammatic and partial schematic
sectional view of an embodiment of the present invention used as a
fluid motor in a fluid system;
[0006] FIG. 2 is a sectional view taken along the line 2-2 of FIG.
1;
[0007] FIG. 3 is a sectional view taken along the line 3-3 of FIG.
1;
[0008] FIG. 4 is a sectional view taken along the line 4-4 of FIG.
1;
[0009] FIG. 5 is a sectional view taken along the line 5-5 of FIG.
1;
[0010] FIG. 6 is a sectional view taken along the line 6-6 of FIG.
1;
[0011] FIG. 7 is a sectional view taken along the line 7-7 of FIG.
1;
[0012] FIG. 8 is a sectional view taken along the line 8-8 of FIG.
1;
[0013] FIG. 9 is an elevational view of a piston taken from FIG.
1;
[0014] FIG. 10 is an end view of the piston of FIG. 9;
[0015] FIG. 11 is sectioned side view of the piston in FIG. 9;
and
[0016] FIG. 12 is a partial diagrammatic and partial schematic
sectional view of the embodiment of the subject invention used as a
fluid pump in a fluid system.
DETAILED DESCRIPTION
[0017] Referring to the embodiment of FIG. 1, a fluid translating
device 10 is illustrated in a fluid system 12. As used in the fluid
system 10 of FIG. 1, the fluid translating device 10 is operating
as a fluid motor and, with respect to FIGS. 1-11, will be referred
to as a fluid motor. It is recognized that the fluid translating
device 10 could also be a fluid pump as will be set forth later
with respect to the fluid system of FIG. 12. All elements of the
fluid motor 10, as hereinafter described with respect to FIGS.
1-11, will apply equally to the same elements when used as a fluid
pump 10. The fluid system 12 also includes a source of fluid, such
as, a hydraulic pump 14 that receives fluid from a reservoir 16 and
delivers pressurized fluid through a control valve 18 to a first
inlet/outlet port 20 of the fluid motor 10. A second inlet/outlet
port 22 is connected to the reservoir 16. It is recognized that the
first and second inlet/outlet ports 20,22 could be connected to the
fluid motor through known SAE ports or other known connections. The
fluid motor 10 is also drivingly connected to a working member 24.
The working member 24 could be a fan for cooling, a final drive for
a wheel or any other well known devices that are driven by fluid
motors.
[0018] The fluid motor 10 includes first and second members 28,30,
a camplate 32, a stationary central shaft 34, a port plate 36 with
a bearing assembly 38 disposed thereabout, a plurality of pistons
40, first and second seal and bearing assemblies 42,44, and an
outer input/output member 46.
[0019] The stationary central shaft 34 defines a reference axis 50
and has a first end portion 52, a second end portion 54 and a
center portion 56. The first end portion 52 includes a diameter 58
of a predetermined size extending from the end thereof to a
shoulder 59 and has a keyway 60 defined therein. The second end
portion 54 includes a diameter 62 of a predetermined size extending
from the end thereof to a shoulder 63 and has a keyway 64 defined
therein. The center portion 56 includes an enlarged spherical
surface 66.
[0020] The first member 28 has a bore 68 defined therein and of a
size to receive the diameter 58 of the first end portion 52 of the
stationary central shaft 34. A keyway 70 is defined in the bore 68
and a key 72 is disposed in the respective keyways 60,70 to locate
the first member 28 relative to the first end portion 52 of the
stationary central shaft 34. The first member 28 is disposed about
the first end portion 52 of the stationary central shaft 34 and an
end face 74 thereof abuts the shoulder 60 and secured thereto by a
fastener mechanism 73.
[0021] The end face 74 of the first member 28 is perpendicular with
the reference axis 50 and is in communication with the first and
second inlet/outlet ports 20,22. The first member 28 has a first
circular groove 76 defined in the end face 74 about the reference
axis 50. The first circular groove 76 is disposed about the
reference axis 50 at a predetermined radius. A second circular
groove 78 is defined in the first member 28 about the reference
axis 50 at the face surface 74. The second circular groove 78 is
disposed about the reference axis 50 at a predetermined smaller
radius. The first circular groove 76 is in communication with the
first inlet/outlet port 20 and the second circular groove 78 is in
communication with the second inlet/outlet port 22.
[0022] The first seal and bearing assembly 42 is disposed within
grooves/slots of a peripheral surface 82 of the first member. In
the subject embodiment, the first seal and bearing assembly 42
includes a seal 84 and a bearing mechanism 86. It is recognized
that other known seal and bearing arrangements could be used.
[0023] The second member 30 has a bore 88 defined therein about the
reference axis 50, a face surface 89, a plurality of blind bores 90
defined therein a predetermined distance away from and about the
reference axis 50 and extends from the end face 89 thereof parallel
to the reference axis 50 to a bottom surface 93, and a peripheral
surface 92. A cavity 94 is defined in the second member 30
extending from the face surface 89 to form a shoulder 96
therein.
[0024] A keyway 98 is defined in the bore 88 and a key 100 is
disposed in the respective keyways 64,98 to locate the first member
28 relative to the second end portion 54 of the stationary central
shaft 34. The second member 30 is disposed about the second end
portion 54 of the stationary central shaft 34 and the shoulder 96
of the second member 30 abuts the shoulder 63 and secured thereto
by a fastener mechanism 102.
[0025] The second seal and bearing assembly 44 is disposed within
grooves/slots of the peripheral surface 92 of the second member 30.
In the subject embodiment, the second seal and bearing assembly 44
is the same as the first seal and bearing assembly 42 described
above.
[0026] The outer input/output member 46 is rotatably disposed about
the first and second members 28,30 and in driving contact with the
working member 24 through a spline tooth arrangement 104 disposed
on the outer peripheral thereof. It is recognized that the working
member 24 could be made integral with the outer input/output member
46 without departing from the essence of the subject invention. The
outer input/output member 46 has a bore 106 defined therein and
operative at respective ends thereof to engage the respective first
and second seal and bearing assemblies 42,44. The center portion of
the bore 106 has a drive engaging portion 108, such as spline teeth
to drivingly mate with the camplate 32.
[0027] The camplate 32 is disposed within the outer input/output
member 46 and is driving connected thereto through a drive engaging
portion 110, such as spline teeth. The drive engaging portion 110
of the camplate 32 and the drive engaging portion 110 are of a size
and shape sufficient to center and align the camplate 32 within the
outer input/output member 46. It is contemplated that, if desired,
the camplate 32 could be made integral with the outer input/output
member 46.
[0028] The camplate 32 has first and second end face portions
112,114 and encircles the center portion 56 of the stationary
central shaft 34. The first end face portion 112 is in abutting
contact with the end face 74 of the first member 28. The first end
face portion 112 has a first circular groove 116 defined therein
about the reference axis 50. The first circular groove 116 is
disposed about the reference axis 50 at a predetermined radius. A
second circular groove 118 is defined in the first end face portion
112 about the reference axis 50. The second circular groove 118
thereof is disposed about the reference axis 50 at a predetermined
smaller radius. The first circular groove 116 is adjacent to and
mates with the first circular groove 76 of the first member 28 and
the second circular groove 118 is adjacent to and mates with the
second circular groove 78 of the first member. Referring to the
cross section of FIG. 2, which illustrates the first end face
portion 112 of the camplate 32, arcuate slots 120 are defined in
the first end face portion 112 extending from the first annular
groove 116 into the first end face portion 112 to form a passageway
122 (FIG. 1). Likewise, arcuate slots 124 are defined in the first
end face portion 112 extending from the second annular groove 118
into the first end face portion 112 to form passageway 126 (FIG.
1).
[0029] In the subject embodiment, a recess 127 is defined in the
second end face portion 114 of the camplate 32 and forms a face
surface 128. The face surface thereof is angled at an acute angle
of 25 degrees with respect to the first end face portion 112 and a
reference plane 129. The acute angle could readily be in the range
of 10 to 35 degrees without departing from the essence of the
subject invention. Referring to the cross section of FIG. 3 which
illustrates the face surface 128 of the second end face portion
114, a first arcuate groove 130 formed by a plurality of
interconnected arcuate slots 132 is defined in the face surface 128
on one side thereof and extends into the second end face portion
114 and connects with passageway 122 (FIG. 1). A second arcuate
groove 134 formed by a plurality of interconnected arcuate slots
136 is defined in the face surface 128 on the opposed side thereof
and extends into the second end face portion 114 and connects with
passageway 126 (FIG. 1). The first and second arcuate grooves
130,134 are each disposed at a predetermined radius about a second
reference axis 137 and each extend in an arcuate direction less
than 180 degrees. The first arcuate groove 130 is defined on one
side of a top dead center position (TDC) and the second arcuate
groove 134 is defined on the opposed side of the TDC position as
illustrated in FIG. 3. It is recognized that the plurality of
arcuate slots 132 of the first arcuate groove 130 could be
connected directly to the respective arcuate slots 120 in the first
end portion 112 and that the plurality of arcuate slots 136 of the
second arcuate groove 134 could be directly connected to the
respective arcuate slots 124 of the first end portion 112 without
departing from the essence of the subject invention.
[0030] The port plate 36 with the bearing assembly 38 disposed
thereabout is located in the recess 127 of the camplate 32. The
port plate 36 has first and second parallel, opposed faces 138,140
with the first opposed face 138 being in mating contact with the
face surface 128 of the second end face portion 114 of the camplate
32. Referring also to FIGS. 4 and 5 which further illustrates the
port plate 36, a plurality of equally spaced formed cavities 142 is
defined through the port plate 36 between the first and second
opposed faces 138,140. The plurality of formed cavities 142 is
maintained at a predetermined distance about the second reference
axis 137. The predetermined distance from the second reference axis
137 of the plurality of formed cavities 142 is substantially the
same as the predetermined radius of the first and second arcuate
grooves 130,134 of the second end face portion 114 of the camplate
32. Since the first and second opposed faces 138,140 are parallel
and the first opposed face 138 is in mating contact with the face
surface 128 of the camplate 32, the angle of the second opposed
face 140 of the port plate 36 is at 25 degrees with respect to the
end face 74 and the reference plane 129 and the angle could also be
within the range of 10 to 35 degrees as set forth previously with
respect to the face surface 128 of the camplate 32. A plurality of
fastener holes 144 are defined in the second opposed face 140 of
the port plate 36 and operative to threadably receive respective
ones of a plurality of fasteners 146 (FIG. 1).
[0031] The plurality of pistons 40 includes individual pistons
40a-i. It is recognized that a different number of pistons and
respective blind bores could be used without departing from the
essence of the subject invention. Referring to FIGS. 8-11 in
conjunction with FIG. 1, the piston 40a is illustrated in more
detail. The piston 40a is a unitary member and includes first and
end second portions 150,152 with a reference piston axis 154
defined longitudinally therethrough and a perpendicular reference
piston plane 155 defined at one end thereof. It is recognized that
other known piston assemblies could be used. For example, piston
assemblies that include a piston having a shoe pivotably secured
thereto. The first end portion 150 of each piston 40a-i is
slideably disposed in the associated blind bore of the plurality of
blind bores 90 to form respective pressure chambers 156 between the
first end portion 150 thereof and the bottom surface 93 of each of
the blind bores 90. Each of the piston 40a-i is the same and
functions the same, therefore, only the piston 40a will be
described in detail.
[0032] The first end portion 150 of the piston 40a has a peripheral
surface 158 extending the length thereof. A balancing slot 160 is
defined in the first end portion 150 in the peripheral surface 158
generally adjacent the end of the piston 40a distal from the second
end portion 152. The balancing slot 160 has a first slot portion
162 near the end of the first end portion with a predetermined
width and a second wider slot portion 164 of a predetermined width
at a predetermined distance from the end of the first end portion
150 of the piston 40a. A cavity 165 is defined in the piston 40a
along the reference piston axis 154 through the first and second
portions 150,152. An orifice 166 is defined in the piston 40a
extending from the cavity 165 therein to the balancing slot 160. It
is recognized that the orifice 166 could be eliminated in some
arrangements as noted below.
[0033] The second end portion 152 of the piston 40a is enlarged
with respect to the first end portion 150 thereof. A piston face
surface 170 is disposed on the second end portion 152 of the piston
40a and forms an acute angle with respect to the reference piston
plane 155. The piston face surface 170 of each piston 40a-i is
operative to slideably mate with the second opposed face 140 of the
port plate 36 at a location to align the respective cavities 165
with the respective ones of the plurality of cavities 142 in the
port plate 36. The acute angle of the piston face surface 170 is
zero to one half degree greater than the acute angle formed between
the second opposed face 140 of the port plate 36 and the first end
portion 112 of the camplate 32. In the subject embodiment, the
acute angle of the piston face surface 170 relative to the
reference piston plane 155, as illustrated in FIG. 11, is 251/2
degrees. It is recognized that the acute angle of the piston face
surface 170 could be the same as the acute angle formed between the
port plate 36 and the reference plane 129. During operation, the
piston 40a can rotate about the axis 154 and improve alignment of
the face 170 thereof relative to the second opposed face 140 of the
port plate 36.
[0034] The second end portion 152 of the piston 40a has a spherical
peripheral surface 172 and the piston face surface 170 has a
plurality of pressure balancing slots 174 defined therein about the
reference piston axis 154. The plurality of pressure balancing
slots 174 is operative, in use, to provide a fluid film at the
piston face surface 170 for lubrication thereof.
[0035] Referring to FIGS. 6 and 7 in combination with FIG. 1, a
piston retainer member 178 having first and second opposed faces
180,182 is set forth and operative to hold the respective pistons
40a-i close to the second opposed face 140 of the port plate 36. A
plurality of formed elongated cavities 184 is defined in the
retainer member 178 between the first and second opposed faces
180,182. The wall surface of each cavity of the plurality of formed
elongated cavities 184 has a spherical shape to mate with the
spherical peripheral surface 172 of the second end portion 152 of
the pistons 40a-i. A plurality of retainer holes 186 are defined in
the retainer member 178 and operative to receive respective ones of
the plurality of fasteners 146. As illustrated in FIG. 1, each of
the pistons 40a-i is disposed through the respective ones of the
plurality of formed elongated holes 186 and the piston retainer
member 178 is secured to the port plate 36 by the plurality of
fasteners 146.
[0036] Referring to FIG. 12, the fluid translating device 10 is
used in a fluid system 12 as a fluid pump. All elements of the
fluid translating device 10 as used and described in FIGS. 1-11 are
the same and will not be described further. Like elements have like
element numbers. In the fluid system 12 of FIG. 12, a power source
190 is drivingly connected to the outer input/output member 46 and
the first inlet/outlet port 20 is connected to the reservoir 16.
The second inlet/outlet port 22 is connected to the working member
24, such as a fluid actuator, through a directional control valve
192. The power source 190 rotates the outer input/output member 46
in the same direction as set forth with that of FIGS. 1-11.
[0037] It is recognized that various other components and/or
arrangements could be used in the subject fluid system 12 without
departing from the essence of the subject invention. For example,
the plurality of blind bores 90 in the second member 30 could be
through bores with sealed plugs inserted at the end of each bore to
establish a blind bore. Likewise, the plurality of fasteners 146
that holds the piston retainer member 178 to the port plate 36
could be replaced by other known methods, such as, by increasing
the depth of the recess 127 in the second end portion 114 of the
camplate 32 and properly positioning a snap ring groove therein and
inserting a snap ring in the snap ring groove to hold the piston
retainer member 178 in its proper location. Additionally, the
bearing assembly 38 could be a hydrostatically balanced and
lubricated bearing.
INDUSTRIAL APPLICABILITY
[0038] In the operation of the fluid system 12 set forth in FIGS.
1-11, wherein the fluid translating device 10 is being used as a
fluid motor, pressurized fluid from the hydraulic pump 14 is
directed, in response to operation of the control valve 18, to the
respective pressure chambers 156 located, as viewed in FIG. 8, on
the left side of the TDC position. The pressurized fluid is
directed from the first inlet/outlet port 20 to the pressure
chamber 156 through the first inlet/outlet port 20, first circular
groove 76 in the first member 28, the first circular groove 116 in
the camplate 32, the arcuate slots 120, the plurality of arcuate
slots 132 in the first arcuate groove 130, through the port plate
36, and the associated cavities 165. The force of the pressurized
fluid acting on the ends of the associated pistons 40f-i results in
the camplate 32 rotating in the direction illustrated in FIG. 3. As
the camplate 32 rotates, the pistons 40a-e move into their
associated blind bores 90 expelling the fluid therefrom. The
expelled fluid returns to the reservoir 16 through the cavities in
the associated pistons 40a-e, across the port plate 36, through the
plurality of interconnected slots 136 in the second arcuate groove
134, the arcuate slots 124, the second circular groove 118 in the
camplate 32, the second circular groove 78 in the first member 28,
and the second inlet/outlet port 22. Since the camplate 32 is
drivingly secured to the outer input/output member 46, the outer
input/output member 46 drives the working member 24. The speed of
the working member 24 is controlled in response to the volume of
pressurized fluid being directed to the fluid motor 10 by the
control valve 18.
[0039] As the camplate 32 rotates, the port plate 36 is permitted
to nutate about the reference axis 50. The bearing assembly 38
permits rotational movement between the camplate 32 and the port
plate 36 while the plurality of formed elongated cavities 184 in
the piston retainer member 178 permits relative movement between
the plurality of pistons 40 and the second opposed face 140 of the
port plate 36.
[0040] The piston face surface 170 lays flat against the second
opposed face 140 of the port plate 36. The plurality of pressure
balancing slots 174 permits an ample amount of lubricating fluid to
be maintained between the piston face surface 170 of the respective
pistons 40a-i and the second opposed face 140 of the port plate 36.
It is necessary to maintain the piston face surface 170 flat
against the port plate 36 in order to minimize leakage thereacross.
In order to offset tolerances between components, the angle of the
piston face surface 170 with respect to the reference piston plane
155 and the parallel reference plane 129 is approximately 1/2
degree greater. The respective pistons 40a-i rotate slightly within
their respective blind bores 90 in response to rotation of the
camplate 36 to ensure that the piston face surface 170 remains flat
against the port plate 36. The slight rotation of the respective
pistons 40a-i is automatic since the portion of the piston face
surface 170 that touches the second opposed face 140 of the port
plate 36 first creates a slight drag force that results in a
twisting force on the piston thus slightly rotating the piston to
make the face surface 170 lay flat on the port plate 36.
[0041] The balancing slot 160 located on the peripheral surface 158
of each piston 40a-i operates to balance the forces acting on the
respective pistons at the piston face surface 170 attempting to
tilt the respective pistons relative to the respective blind bores
90. Pressurized fluid within the respective pressure chambers 156
is directed into the balancing slot 160 through the orifice 166. It
is recognized that the orifice 166 could be eliminated and the
pressurized fluid in the respective pressure chambers 156 would be
directed to the balancing slot 160 via the sliding clearance
between the peripheral surface 158 of the piston and the associated
blind bore 90. When the respective pistons 40a-i are extended from
the respective blind bores 90, the force acting on the piston face
surface 170 tends to urge the respective pistons 40a-i, as viewed
in the FIGS. 1, 11 or 12, in a counterclockwise direction. As the
piston tips or cants in the bore, fluid enters into the balancing
slot 60, either through the orifice 166 and/or around the piston
40a due to the larger eccentric clearances and pressurizes the
balancing slot 160 which applies a force to the wider slot portion
164 that is larger than the force acting in the first portion 162
thus urging the respective pistons 40a-i to re-straighten within
the blind bore 90. This improves piston lubrication thus reducing
subsequent wear and can actually reduce leakage since the
respective pistons have reduced eccentricity.
[0042] In the operation of FIG. 12 wherein the fluid translating
device 10 is being used as a pump, the power source 190 drivingly
rotates the outer input/output member 46 which in turn rotates the
camplate 32 in the direction illustrated in FIG. 3. As the camplate
32 rotates, the pistons 40a-e on the right side of the TDC
position, as viewed in FIG. 8, are urged into the respective blind
bores 90 thus forcing pressurized fluid therefrom. The pressurized
fluid is directed through the respective cavities 165, across the
port plate 36, through the plurality of interconnected slots 136 in
the second arcuate groove 134, the arcuate slots 124, the second
circular groove 118, the second circular groove 78, the second
inlet/outlet port 22, through the directional control valve 192 to
the working member 24.
[0043] At the same time the pistons 40f-i are moving in a direction
out of the respective blind bores 90. In order to fill the
associated pressure chambers 156, fluid is directed thereto from
the reservoir 14 through the first inlet/outlet port 20, the first
circular groove 76, the first circular groove 116, the arcuate
slots 120, the plurality of interconnected arcuate slots 132 in the
first arcuate groove 130, across the port plate 36, and through the
cavities 165 in the associated pistons. The remaining operation of
the fluid translating pump 10 of FIG. 12 is the same as that
described with respect to the operation set forth with respect to
FIGS. 1-11.
[0044] In view of the above, it is readily apparent that the
subject fluid translating device 10 provides a more compact and
efficient unit. This is evident, in part, by the fact that the
outer input/output member 46 is maintained aligned about the first
and second members by the first and second seal and bearing
assemblies 42,44 regardless of the forces being applied thereto.
Also, by having the first and second members 28,30 secured to a
stationary central shaft 34, the fluid translating device is more
compact and less costly to produce.
[0045] Other aspects, objects and advantages of the subject
invention can be obtained from a study of the drawings, the
disclosure and the appended claims.
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