Compact pump or motor with internal swash plate

Information

  • Patent Grant
  • 6572344
  • Patent Number
    6,572,344
  • Date Filed
    Monday, November 26, 2001
    22 years ago
  • Date Issued
    Tuesday, June 3, 2003
    21 years ago
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.
Description




TECHNICAL FIELD




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




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.




The present invention is directed to overcoming one or more of the problems set forth above.




SUMMARY OF THE INVENTION




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





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;





FIG. 2

is a sectional view taken along the line


2





2


of

FIG. 1

;





FIG. 3

is a sectional view taken along the line


3





3


of

FIG. 1

;





FIG. 4

is a sectional view taken along the line


4





4


of

FIG. 1

;





FIG. 5

is a sectional view taken along the line


5





5


of

FIG. 1

;





FIG. 6

is a sectional view taken along the line


6





6


of

FIG. 1

;





FIG. 7

is a sectional view taken along the line


7





7


of

FIG. 1

;





FIG. 8

is a sectional view taken along the line


8





8


of

FIG. 1

;





FIG. 9

is an elevational view of a piston taken from

FIG. 1

;





FIG. 10

is an end view of the piston of

FIG. 9

;





FIG. 11

is sectioned side view of the piston in

FIG. 9

; and





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




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

FIG. 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.




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


.




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


.




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


.




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


.




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.




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.




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


.




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.




The outer input/output member


46


is ratatably 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


.




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


.




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


).




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.




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


).




The plurality of pistons


40


includes individual pistons


40




a-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

FIG. 8-11

in conjunction with

FIG. 1

, the piston


40




a


is illustrated in more detail. The piston


40




a


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


40




a-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


40




a-i


is the same and functions the same, therefore, only the piston


40




a


will be described in detail.




The first end portion


150


of the piston


40




a


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


40




a


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


40




a.


A cavity


165


is defined in the piston


40




a


along the reference piston axis


154


through the first and second portions


150


,


152


. An orifice


166


is defined in the piston


40




a


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.




The second end portion


152


of the piston


40




a


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


40




a


and forms an acute angle with respect to the reference piston plane


155


. The piston face surface


170


of each piston


40




a-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 25½degrees. 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


40




a


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


.




The second end portion


152


of the piston


40




a


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.




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


40




a-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


40




a-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


40




a-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


.




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

.




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




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


40




f-i


results in the camplate


32


rotating in the direction illustrated in FIG.


3


. As the camplate


32


rotates, the pistons


40




a-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


40




a-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


.




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


.




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


40




a-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 ½degree greater. The respective pistons


40




a-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


40




a-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


.




The balancing slot


160


located on the peripheral surface


158


of each piston


40




a-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


40




a-i


are extended from the respective blind bores


90


, the force acting on the piston face surface


170


tends to urge the respective pistons


40




a-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


160


, either through the orifice


166


and/or around the piston


40




a


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


40




a-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.




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


40




a-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


.




At the same time the pistons


40




f-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

.




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.




Other aspects, objects and advantages of the subject invention can be obtained from a study of the drawings, the disclosure and the appended claims.



Claims
  • 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 hollow 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 translation 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, 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 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 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.
US Referenced Citations (9)
Number Name Date Kind
2821932 Lucien Feb 1958 A
3981630 Leduc et al. Sep 1976 A
4522112 Nomura Jun 1985 A
5220225 Moon, Jr. Jun 1993 A
5396768 Zulu Mar 1995 A
5415596 Zulu May 1995 A
5423183 Folsom Jun 1995 A
5545098 Zulu Aug 1996 A
6179574 Yie Jan 2001 B1