US3540351A

US3540351A - Hydraulic pump or motor

Info

Publication number: US3540351A
Application number: US292267A
Authority: US
Inventors: George A Schauer
Original assignee: Sundstrand Corp
Current assignee: Sundstrand Corp
Priority date: 1963-07-02
Filing date: 1963-07-02
Publication date: 1970-11-17
Anticipated expiration: 1987-11-17

Description

United States Patent Inventor George A. Schauer [56] References Cited Rockford, Illinois UNITED STATES PATENTS P 3 892,804 7/1908 Burbank |23/43(A) gfif 3: 893,558 7/1908 Williams .1 103/162 cc S a d C r 2,741,188 4/1956 Wemhoner 103/162 2,875,701 3 1959 Ebert 103/162 a corporation of Delaware Continuation-impart of Ser. No. 114,366, FOREIGN PATENTS June 2, l96l,abandoned 220,417 8/1924 Great Britain 103/162 539,637 9/1941 Great Britain 1. 103/162 Primary Exan1iner-Wil1iam L. Freeh HYDRAULIC PUMP 0R MOTOR Attorney-Hofgren, Wegner, Allen, Stellman & McCord 15 Claims, 4 Drawing Figs.

US. Cl 91/506, m

74/60, 103/38. 92/155, 92/136 ABSTRACT: An axial piston hydraulic unit of the swashplate lnt.Cl ..F04b 41/00, type comprising a rotary barrel having pistons reciprocably F04b 1/02, F16h 33/00 mounted therein, a stroke regulator, a crosshead between the Field ofSearch 74/60,22, barrel and the stroke regulator and links between both the 63; l03/38A, 173, 162; 121/62; 123/43A, 44(A); crosshead and the barrel and between the crosshead and the 230/186 stroke regulator.

Patented Nov. 17, 1970 Sheet 1. 012

g N w w .5 5 a w a m 4 w 9 5w a 52 33 6 k 0 1 g Q w 1 l m a my 8 1 F F w a Geo Patented Nov. 17, 1970 3,540,351

Sheet ,2 or 2 HYDRAULICPUMP'OR'MOTOR The present invention relates'to hydraulic pumps and motors and more particularly to hydraulic pumps and motors of the piston and cylindertype where reciprocation ofthe pistons is accomplished by means of relative rotation between a cylinder block and a cam plate.

This application is a continuation'impart of my copending U.S. Pat. application Ser. No. 114,366 now abandoned filed June 2, I961 entitled "Hydraulic Pump or Motor.

It is the general objectof the present invention to produce a new improved hydraulic pump or motor ofthe type described.

It is a more particular object of'the invention to produce a hydraulic pump or motor wherein side forces on pistons induced by an inclined cam plate are substantially reduced.

It is a further object of the invention to produce a hydraulic pump or motor of either fixed or variable displacement which is compact in size and where the displacement may be varied through a relatively large range without the necessity of complicated systems providing for movement of relatively complex parts. I

A further and more detailed object of the present invention is to provide a hydraulic pump ormotor of the cylinder blockcam plate type wherein a crosshead is positioned intermediate the cylinder and cam plate with the crosshead being provided with a plurality of sliding devices equal in number to the pistons in the cylinder block, with the sliding members being pivotally connected to the pistons on the one hand and to the cam plate membe'ron the other.

Other and further objects and advantages of the present invention will be readily apparent from the following detailed description taken in connection with the accompanying drawings. in which:

FIG. I is a sectional view through the center line of an embodiment of the present invention;

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 olFlG. 1;

FIG. 4 is a view like'FlG. I of a modified form of the invention.

While this invention is susceptible of embodiment in many different forms, there is shown inthe drawings and will herein be described in detail several embodiments of the invention, with the understanding that the presentdisclosure is to be considered as an exempliflcation ofthe principles ofthe invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

Referring first to FIG. I, there is shown a housing including a main housing member 10, a manifold end member 11, and a drive shaftend member 12. Rotatably mounted in the housing is a drive shaft 13 carrying a crosshead 14, the drive shaft being carried by bearings I5 located in the end member I2. Rotatably supportingcrosshead I4-is bearing I6.

Also located within the housing I0 is a cylinder block I7 rotatably carried by hearing I8. The cylinder block reciprocably carries a plurality of pistons sliding in cylinders 21 formed in the cylinder hlock. Five such cylinders and pistons are provided for in the cylinder block.

In order to hold the cylinder block 17 against the .port plate formed on the inner face ofthe manifold end member 11 there is provided a piston 24 slidable in a central bore 25 in the cylinder block, with the piston having a ball 26 secured to one end thereof pivotally received in socket 27 formed in the end of the shaft 13. A spring 28 bears at one end against one side of the piston 24 and at its other end against a step 29 formed in the cylinder block to urge the same into contact with the manifold housing end 11.

Links 30 are each provided with balls 31 and 32 at opposite ends thereof. The balls 31 are pivotally secured in sockets 33 provided in each of the pistons 20 while the opposite balls 32 are pivotally secured in sockets 34 provided in slide members 35. Slide members 35 are slidably mounted in bores 36 provided in the crosshead I4. there being one slide member 35 for each of the pistons 20. A second plurality of links 37 are each provided with balls 38 and 39 at opposite ends thereof with balls 38 being pivotally secured in sockets 40 in each of the slide members 35. The balls 39 are pivotally secured in sockets 41 provided in ring member 42. The ring member 42 is supported on bearing 55 forming a part of a cam plate or swashplate member 60. The cam plate 60 has a pair ofarms 62 rigidly secured thereto with the arms being pivotally connected to the housing member I0 as generally indicated at 63. The cam plate 60 may be connected to a suitable linkage (not shown) to tilt it at various angles to the center line ofthe drive shaft 13 thereby to vary the stroke ofthe pistons 20.

Referring now to FIG. 3, a passage 70 and a passage H are provided in the manifold end member II. The passage 70 connects with a kidney-shaped port 72 and the passage 7I connects with a second kidney-shaped port 73.

As the cylinder block 17 rotates in bearing 18.

passages

74, 75, 76, 77 and 78 (FIG. 2) in the cylinder block successively register with the

ports

72 and 73. The connections of passages 74 and 76 with the cylinders 21 are shown in FIG. 1. Each of the five cylinders in the cylinder block has a fluid connection successively in

passages

70 and 71 as the cylinder block rotates.

A set of bolts 83 secures the manifold end member II to the main housing member 10 and a set of bolts 84 secures the drive shaft end member 12 to the main housing member 10. With members 11 and I2 bolted in place as shown in FIG. 1, spring 28 is compressed to hold block 17 against end member 11 with sufficient force to prevent excessive fluid leakage while allowing the contacting surfaces of block 17 against end member 11 to be lubricated by the fluid being transported through the passages and ports.

When the embodiment of the invention shown in FIG. I is operated as a pump, the shaft 13 is driven by a power source (not shown).

The block 17 is connected through the pistons 20 and links 30 to the slide members 35, and as the crosshead I4 is splined to and hence driven by the shaft 13 the cylinder block 17 is caused to rotate therewith. To accomplish this transmission of torque, a U-shaped bearing flange portion is provided on each of the pistons 20 positioned to engage collars 92 pro vided on each of the links 30. These flanges so surround their respective collars that a two-point contact is provided between each piston and its attached link to transmit torque from the crosshead I4 to the cylinder block I7 during clockwise and counterclockwise rotation.

With the cam plate 60 in the position shown in FIG. I. maximum piston stroke is obtained. The ring element 42 being connected to the shaft 13 through the crosshead 14, the slider members and the links 37 rotate with the shaft 13.

To accomplish this driving, bearing flange portions 94 are provided on ring member 42 for each of the links 37. These flanges so surround their respective links that a two-point contact is provided between each link and ring member 42 to transmit torque from the crosshead I4 to the ring member 42 during both clockwise and counterclockwise rotation. Any other mechanical connection that will maintain angular position between the crosshead and the ring member without interference with the operation may be substituted for the flanges 94.

As the angle of the cam plate 60 is varied from its position in FIG. I, the length of the stroke of the pistons is shortened. As the shaft I3, the crosshead l4 and the block 17 rotate in a clockwise direction when viewed from manifold end member II, the cylinder bores communicate with the port 73 during the time that the pistons are being withdrawn from the cylinder bores and the cylinder bores communicate with the port 72 during the time the pistons are being forced into the cylinder bores. Therefore, fluid is taken from the passage 71 and forced out the passage 70 to provide a pumping action. The quantity of fluid to be pumped is controlled by the rotational velocity of the drive shaft 13 and the position of the cam plate 60. A greater rotational velocity of shaft 13 increases the pumping rate. A movement of the cam plate from the top of the housing I0 down to the position shown in FIG. I increases the pumping rate to a maximum for a given rotational velocity of the shaft 13. Therefore,the control of the cam plate 60 provides a convenient pumping rate control without varying the rotational velocity ofthe shaft 13.

To operate the embodiment of the invention shown in FIG. 1 as a motor, a hydraulic fluid is forced under pressure in either the passage 70 or the passage 71. This forces the pistons to retract from the cylinder bores when the cylinders communicate with the port which is receiving the high pressure hydraulic fluid. This causes the cylinder block 17 to be rotated and thereby rotates the shaft 13. Introduction ofthe high pressure fluid into passage 70 produces counterclockwise rotation and introduction of high pressure fluid into passage 71 produces a clockwise rotation.

Referring again to FIG. 1, assume that an axial force exists on the pistons 20. This force is resisted by the force along the axis of the sliders and by the sidewalls of the bores 36. The force exerted along the axis of the sliders 35 is resisted by a force exerted by the ring member 42 through the links 37. With the ring member 42 in the position shown in FIG. 1, it also exerts a side force on the bores 36 of the erosshead 14. As the cam plate 60 is rotated about the pivot axis 63, the stroke of the pistons 20 is reduced until the block 17 rotates without any axial motion (stroke) of the pistons in their respective cylinders. Thus, the position of the cam plate 60 and ring member 42 determines the length of the stroke of the pistons. As many pistons and cylinders may be employed as will fit into the rotating block 17. For purposes of illustration, a block containing five pistons and cylinders has been shown in the drawings.

Whether the present device is operating as a pump or as a motor, the ring member 42 will be held in contact with the bearings of the cam plate by the force created by the fluid on the high pressure side. Even when the device is operating as a pump with a suction being created on the low pressure side, the force of the pumping action against the fluid on the high pressure side will be sufficient to overcome the tendency of the suction side to pull away from the cam plate. However, additional bearing means to hold the ring in position may be required for low pressure operation.

lt can be noted from the above description that when the axis of the ring member 42 is parallel to the axis ofthe cylinder block 17, the stroke length is zero. In the structure shown in HQ. 1, the cam plate 60 can be rotated about the shaft portions 63 only far enough to reduce the stroke to zero. Therefore, the only method of reversing the pumping action between the passages will be to reverse the rotational direction of the drive shaft 13. However, the physical structure of the cam plate and housing may be such that the cam plate can be rotated about its pivot axis 63 until the axis ofthe ring member has rotated through an angle which would first bring it parallel to the axis of the cylinder block and then beyond this parallelism so that the direction of the pumping action between the passages and 71 would be reversed without changing the rotational direction of the drive shaft 13. When the device is used as a motor the direction of rotation of the shaft 13 will be reversed without reversing the direction of fluid flow from one passage to the other by having the axis of the ring member pass through parallelism to the axis of the cylinder block 17.

It can be noted from FIG. 1 that the angle between the axis of the drive shaft 13 and the axis of the cylinder block 17 may be reduced until it becomes zero and the device will continue to function in the manner described above. The only change produced by reducing the angle between the axis of the shaft 13 and the axis of the block 17 is to shorten the length of the stroke for a given position ofthe cam plate 60. Thus, two basic design characteristics of the present invention may be summarized as follows: First, the length ofthe stroke ofthe pistons is dependent upon the angle between the axis of the ring member and the axis of the cylinder block with the stroke increasing as the axis of the ring member diverges from parallelism with the axis of the block. Second, the fluid direction may be reversed without changing the direction of rotation of the shaft 13 when the device is utilized as a pump or the rotational direction of the shaft 13 and the cylinder block 17 may be reversed without changing the introduction of high pressure fluid from one passage to the other when the device is used as a motor by rotating the axis of the ring member through parallelism with the axis of the block 17. Therefore, any combination of controls which reverses or changes the rate of either pumping or motor operation of the present device by varying the angle of the axis of the ring member to the axis of the cylinder block 17 is within the scope ofthe present invention.

A somewhat modified form of the invention is shown in FIG. 4. Referring thereto, there is provided a housing closed at one end by an end manifold plate 111 and at the other end by a shaft end member 112. A drive shaft 113 is rotatably supported within the housing and carries at one end thereof a erosshead 114, the other end of the shaft being mounted in bearing 115, and the erosshead 114 is rotatably carried by bearing 116. A cylinder block 117 is rotatably supported in the housing and carries a plurality of pistons 120 in cylinders 121. Like the embodiment of FIG. 1, the cylinders 121 extend generally parallel to the axis of rotation of the cylinder block but some angularity is permissible and may even be desirable under certain circumstances.

To produce rotation of the cylinder block 117, a shaft 122 is splined thereto at 123 and is secured by means of a universal joint 124 to the shaft 113.

To hold the cylinder block 117 against the port plate formed on the inner face ofend plate 111, there is provided a spring 128 compressed between a step 125 on the shaft 122 and a ring member 126 bearing against the cylinder block 117.

Pivotally connected to each of the pistons 120 are links 130 having a ball 131 at one end thereofand a second ball 132 is at the opposite end thereof with the balls 132 being pivotally secured to slide members 135 slidably mounted in bores 136 in erosshead 114.

A second series of links 137 are provided with

balls

138 and 139 at opposite ends thereof engaging sockets 140 and 141 provided in the slide members and in a rotatable cam plate 142, respectively. The cam plate 142 is rotatably supported by a cam member movably carried on two pairs of wheels 151 bearing against arcuate surface 152 formed on the inner face of end member 112. Movement of the cam member in said path is accomplished by means of a hydraulic piston and cylinder device connected by means ofa link 153 to the cam member 150 with the opposite end of the link being secured to piston 154 reciprocable in cylinder 155. Fluid under pressure may be supplied through a port 156 to the cylinder 155 to move the piston 154 to the position shown in the drawing. At its maximum stroke, the cam member bears against an adjustable stop 156 to limit the extent of its movement. Movement of the cam member upon withdrawal fluid from the cylinder 155 is accomplished through the natural moment thereof tending to move the same toward minimum stroke position.

Again, as in the first embodiment, the side forces or side thrusts which would otherwise be directed against the pistons 120 are for the most part taken up by the slide members 135 operating in their bores 136. Furthermore, relatively large changes in amplitude of reciprocation of the pistons 120 can be accomplished through the movement of the cam member 150 in the manner previously described.

lclaim:

1. In a fluid pump or motor device, the combination of a housing, a cylinder block rotatably mounted about a first axis, cylinders in said cylinder block having axes' substantially parallel to said first axis, a shaft, a erosshead secured to said shaft, said shaft and erosshead being rotatably mounted about a second axis, pistons slidably mounted in said cylinders, bores in said erosshead having axes parallel to said second axis, a sliding member slidably mountedin each said bore, means for pivotally connecting said slide members respectively to said pistons, and means for producing reciprocatory motion of said pistons as said cylinder block and said crosshead are rotated comprising a member rotatably mounted about a third axis intercepting said first axis, and means for pivotally connecting each said slide member to said member.

2. in a fluid pump or motor device. the combination of a cylinder block rotatably mounted about a first axis. cylinders in said cylinder block having axes parallel to said first axis, a shaft, a crosshead secured to said shaft, said shaft and crosshead being rotatably mounted about a second axis, pistons slidably mounted in said cylinders, means for transmitting rotary motion between said cylinder block and said crosshead, bores in said crosshead having axes parallel to said second axis, a sliding member slidably mounted in each said bore, means for pivotally connecting each said slide member to a said piston, means for producing reciprocatory motion of said pistons as said cylinder block and said crosshead are rotated comprising a cam member rotatably mounted about a third axis, said third axis intercepting said first axis, means for pivotally connecting each said slide member to said cam member whereby a stroke limit of the reciprocating motion of said pistons is reached whenever the rotation of the cylinder block positions a piston in the plane which includes said first and third axes and whereby said stroke limits are determined by the angle between the first and third axes, and fluid passage means communicating with open ends of said cylinders whenever said cylinders are on one side of said plane, and another fluid passage means communicating with the open ends ofsaid cylinders,

3. in a fluid pump or motor device, the combination of a housing, a cylinder block rotatably mounted in said housing about a first axis, cylinders in said cylinder block having axes parallel to said first axis, a shaft, a crosshead splined to said shaft, said shaft and crosshead being rotatably mounted in said housing about a second axis, pistons slidably mounted in said cylinders, means for transmitting rotary motion between said cylinder block and said crosshead, bores in said crosshead having axes parallel to said second axis, a sliding member slidably mounted in each said bore, a link pivotally connected to each said slide member and to a said piston, means for producing reciprocatory motion of said pistons as said cylinder block and said crosshead are rotated comprising a cam member rotatably mounted in said housing about a third axis, said third axis intercepting said first axis, means for varying the angle between said first and third axes in opposite directions from parallelism, and a link pivotally connected to each said slide member and to said cam member whereby a stroke limit of the reciprocating motion of said pistons is reached whenever the rotation of the cylinder block positions a piston in the plane which includes said first and third axes and whereby said stroke limits are varied by varying the angle between the first and third axes, and fluid passage means comprising a fluid passage in saidhousing communicating with open ends of said cylinders whenever said cylinders are on one side of said plane, and another fluid passage in said housing communicating with the open ends of said cylinders whenever said cylinders are on the opposite side of said plane whereby fluid is pumped from one of said passages to the other of said passages whenever said third axis is on one side of parallelism with said first axis and a torque is applied to said shaft to rotate it in one direction and fluid is pumped from the said other of said passages to said one ofsaid passages whenever either said third axis is rotated through parallelism with said first axis or a reverse torque is applied to said shaft to rotate it in the opposite direction and whereby said shaft is rotated in one direction whenever said third axis is on one side of parallelism with said first axis and fluid is supplied under pressure to said one of said-passages and said shaft is rotated in the opposite direction whenever either said third axis is rotated through parallelism with said first axis or fluid is supplied under pressure to said other ofsaid passages.

4. In a fluid pump or motor device, the combination of a housing, a cylinder block rotatably mounted about a first axis, cylinders in said cylinder block having axes substantially parallel to said first axis, a crosshead rotatably supported in the housing for rotation about a second axis, pistons slidably mounted in said cylinders, bores in said crosshead having axes parallel to said second axis, a sliding member slidably mounted in each said bore, means for pivotally connecting said slide members respectively to said pistons, and means for producing reciprocatory motion of said pistons as said cylinder block and said crosshead are rotated comprising a member rotatably mounted about a third axis intercepting said first axis, and means for pivotally connecting each said slide member to said member.

5. in a fluid pump or motor device, a cylinder block having an annular series of axially extending cylinders disposed around an axis and pistons reciprocable in the cylinders, a crosshead having an annular series of bores around an axis inclined to the cylinder block axis and slide members corresponding respectively to the pistons and reciprocable in the bores, a cam plate having an axis inclined to the axis of the crosshead, means connecting the pistons respectively to the slide members for reciprocation together, other means connected respectively to the slide members and engaging the cam plate, means for causing rotation of the cylinder block and crosshead relative to the cam plate to reciprocate the slide members and pistons, and valve means for admitting fluid to and exhausting fluid from the cylinders on reciprocation of the pistons. v

6. in a hydraulic pump or motor having a cylinder block member, a plurality of annularly arranged cylinders in the block member and pistons reciprocable in the cylinders, means for reciprocating the pistons comprising a swashplate member having a face arranged to be angularly inclined to the axis of said cylinders, a crosshead positioned intermediate the cylinder block member and the swashplate member, a plurality of devices slidably mounted in said crosshead, first means linking the devices to the swashplate member to translate rotary motion of the swashplate into reciprocatory motion of the devices, and second link means pivotally connecting the devices to the pistons to reciprocate the pistons, said second linking means being aligned generally parallel to the axis of the cylinders to transmit only axial forces to the pistons in the reciprocation thereof. I

7. in a hydraulic pump or motor having a cylinder block member, a plurality of annularly arranged cylinders in the block member, the axis of said cylinders being normal to a first plane andpistons reciprocahle in the cylinders, means for reciprocating the pistons comprising, a swashplate member having a face movable to a second plane inclined to the first plane, a crosshead positioned intermediate the cylinder block member and the swashplate member, a plurality of devices mounted in said crosshead member for sliding movement along parallel axes normal to a third plane inclined intermediate the first and second planes, first means linking the devices to the swashplate member to translate rotary motion of the swashplate into reciprocatory motion of the devices, and second means linking the devices to the pistons to reciprocate the pistons, said second linking means being aligned generally parallel to the axis of the cylinders to transmit only axial .forces to the pistons in the reciprocation thereof.

8. A pump having a housing, a drive shaft, a crosshead mounted on said drive shaft and driven thereby, a cam plate about said drive shaft spaced from said crosshead, a rotatable cylinder block driven by said drive shaft and inclined relative to said crosshead and said cam plate, a plurality ofcylinders in said cylinder block having inlet and outlet means, a plurality of pumping pistons reciprocally mounted at one end in said cylinders in said block, each piston having a rod with the rod end received by said crosshead for actuation of by said cam plate so that rotation of said cylinder block causes reciprocation of said pistons in said cylinders, and force-dividing means comprising means in said crosshead for subjecting said crosshead only to forces radial thereto and means on said cam plate for subjecting said cam plate only to forces normal thereto.

9. In a rotating cylinder block pump wherein pumping action is accomplished by the reciprocation of pistons in cylinders in said block. each having a rod operably associated with a rotating crosshead and a nonrotating cam plate, and wherein said reciprocation is caused by the inclination of said rotating cylinder block relative to said rotating'crosshead and said cam plate, the improvement which comprises means for dividing forces received by said crosshead and cam plate from said piston rods including means in said crosshead for subjecting said crosshead to forces only radial thereto and means in said cam plate for subjecting said cam plate to forces only normal thereto.

10. in a fluid pump or motor device, the combination of a housing. a cylinder block rotatably mounted about a first axis. cylinders in said cylinder block having axes substantially parallel to said first axis. a crosshead rotatahly supported in the housing, pistons slidably mounted in said cylinders. bores in said crosshead. a slide member mounted in each said bore. link means for pivotally connecting said slide members respectively to said pistons; and means for producing rcciprocatory motion of said pistons as said cylinder block and said crosshead are rotated including a cam member mounted about a second axis inclined with respect tosaid first axis intercepting said first axis.,and link means pivotally connecting said slide members respectively to said cam member.

11. In a fluid pump or motor device. the combination of a housing. a cylinder block rotatably mounted about a first axis. cylinders in said cylinder block having axes substantially parallel to said first axis. a crosshead rotatably supported in the housing for rotation about a second axis. pistons slidably mounted in said cylinders, bores in said crosshead, a slide member mounted in each said bore. means connecting said slide members respectively to said pistons. and means for producing reciprocatory motion of said pistons as said cylinder block and said crossheadarc rotated including a cam member mounted about a third axis intercepting said first axis. said cam memberbeing connected to reciprocate said sliding members. I

12. The device according to claim 10. and further including means for transmitting rotary motion between said cylinder block and said crosshead including means on each piston for maintaining its associated link generally coaxial with the piston. I

[3. The device according to claim 10. including a unitary annular ring rotatable relative to said cam plate and pivotally connected with the link means interconnecting the slide members and the cam plate.

14. The device according to claim 13. including means for transmitting rotary motion betweensaid crosshead and said annular ring. v v 7 15. The device according to claim 14. in which said means for transmitting rotary motion between said crosshead and said annular ring includes means on said annular ring for maintaining the links connected thereto generally normal to the cam plate.