US3543649A - Axial piston pump or motor device - Google Patents

Axial piston pump or motor device Download PDF

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Publication number
US3543649A
US3543649A US753560A US3543649DA US3543649A US 3543649 A US3543649 A US 3543649A US 753560 A US753560 A US 753560A US 3543649D A US3543649D A US 3543649DA US 3543649 A US3543649 A US 3543649A
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United States
Prior art keywords
cylinder block
shaft
backplate
axial
cylinder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US753560A
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English (en)
Inventor
Robert J Martin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cessna Aircraft Co
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Cessna Aircraft Co
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Publication date
Application filed by Cessna Aircraft Co filed Critical Cessna Aircraft Co
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Publication of US3543649A publication Critical patent/US3543649A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B3/00—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F01B3/0032—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
    • F01B3/0044—Component parts, details, e.g. valves, sealings, lubrication
    • F01B3/0052—Cylinder barrel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B3/00—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F01B3/0082—Details
    • F01B3/0085—Pistons
    • F01B3/0088—Piston shoe retaining means

Definitions

  • the cylinder block is supportingly engaged by abutment means on the drive shaft to limit axial separation of the cylinder block away from the backplate to a predetermined maximum clearance. Selective adjustment is achieved through means which vary the effective axial position of the shaft abutment means.
  • Fluid power devices, pumps and motors, of the reciprocating axial piston-type are well known and consist mainly of a rotary cylinder block drivingly affixed to a shaft and having a concentric ring of cylinder bores spaced about the axis of the shaft with pistons disposed for reciprocation therein.
  • the outer ends of the pistons are formed as spherical bearings to which are swaged flanged shoes having a bearing face.
  • Rotative about an axially movable spherical collar affixed to the shaft is a spider plate which engages the socketed piston shoes.
  • An inclined or inclinable thrust or swashplate bears against the bearing face of the flanged shoes to receive or to transmit force to or from the pistons upon rotation of the block and pistons.
  • a stationary baclcpl'ate mates with the face of the cylinder block and provides properly phased inlet and outlet passages communicating through ports in the block with each cylinder upon relative rotation of the block.
  • the term backplate as used herein refers to the plate which is secured to the housing and mates with the cylinder block in known manner to successively connect the cylinder ports and inlet and outlet passages upon rotation of the cylinder block.
  • a valve plate or port plate may be interposed between the backplate and cylinder vblock.
  • This scheme is effective to bias both the cylinder block against the valve plate and the pistons outwardly against the swashplate; however, it is disadvantageous in that the same spring force acts in both directions, as it has been discovered that, in some cases, the force necessary to maintain the pistons in contact with the swashplate is much greater than the force necessary to maintain engagement between the cylinder block and backplate.
  • the use of two separate springs has been proposed. In this latter arrangement, a first coil spring disposed about the drive shaft engages a grounded abutment, such as a collar on the shaft, and acts against the cylinder block through a snapring arrangement.
  • Second spring means also acting against the abutment exerts a spring force against the spherical collar biasing the pistons.
  • the first and second springs act independently in opposite directions and are both grounded to the shaft at the common abutment.
  • This latter scheme while overcoming some of the objections of other prior art devices employing springs, presents difficult problems of assembly and disassembly.
  • all of these prior art designs have the common disadvantage that due to the biasing force applied to the cylinder block, friction and drag during start-up and zero pressure operation is substantial. This, it will be appreciated, necessitates high starting torque in pump units, increases wear, and reduces starting output torque of axial motor units.
  • Another object of this invention is to provide in an axial piston hydraulic unit a means of adjusting the relationship of the cylinder block to its mating backplate surface, eliminating the need for spring loading of the cylinder block onto the backplate.
  • a more particular object of this invention is to provide a means for limiting the axial separation of the cylinder block and backplate components in an axial piston unit by abutment means on the shaft engaging the block, the effective axial position of the shaft abutment being selectively adjustable.
  • Another object of this invention is to provide an axial fluid device in which the cylinder block is adjustably constrained from axial movement in one direction but is free to follow deflections of the backplate in the other to insure proper sealing at all operating conditions.
  • Another object is to provide an improved axial fluid device which facilitates assembly and disassembly, both in the shop and field.
  • an axial piston hydraulic device of the type heretofore described is provided with a central recess in the cylinder block around the drive shaft.
  • Biasing means as for example a spring transmitting force through pins in bores in the cylinder block, act against an adjustable sleeve and engage the spherical collar slidably splined to the shaft to urge the piston shoes into engagement with the swashplate.
  • An abutment is provided on the drive shaft which acts to effectively engage the cylinder block in a predetermined position in cooperation with an abutment in the cylinder block within the recess.
  • Axial adjustment of the cylinder block in relation to the unit body is achieved by moving the effective position of the abutment on this shaft. This may be done, for example, by shims or by the abutment itself being provided with means for adjustability.
  • FIG. I is a longitudinal sectional view of the hydraulic device constructed in accordance with the invention.
  • FIG. 2 is a longitudinal sectional view of another embodiment incorporating the present invention.
  • FIG. 3 is an enlarged detail view of a portion of FIG. 1 with maximum axial separation of the cylinder block from the backplate being shown in exaggerated proportion.
  • a pump or motor is generally indicated at it), having a housing 11 and backplate 13 defining a central cavity 12.
  • Shaft bearing 14 is pressed into the end of housing 1 1.
  • the main shaft bearings 14 and 16 support shaft for rotation within the housing and are designed to accommodate the radial and axial thrust loadings occurring during operation of the unit.
  • cylinder block 20 is rotatably connected by axial splines 21. on shaft 15 cooperating with loose fitting grooves 22 in the cylinder block.
  • This splined connection allows relative axial movement of cylinder block 20 with respect to shaft 15, as well as providing some compensation for angular misalinement of the parts.
  • Annular bores 23 equally spaced and radially disposed about the axis of shaft 15 accommodate pistons 24 which are formed having spherical outer ends 25.
  • Flanged piston shoes 26 are swaged onto piston ends 25 to allow universal movement.
  • Spider plate engages the shoes 26 and carries the shoes for slidable engagement with swashplate 33.
  • Spider 30 is secured for pivotal movement at its center to spherical collar 31 which is also cooperatively splined to shaft splines 21 at grooves 32 for slidable movement along shaft 15.
  • Swash or thrust plate 33 contacts the bearing faces of piston shoes 26 and is inclinable in trunnions, not shown, mounted in housing 11.
  • the inclination of the swashplate controls the stroke of the pistons and, accordingly, the displacement and operating pressure of the unit during relative rotation of the cylinder block.
  • Backplate 13 having a face 38 of specially hardened material, has ports 36 which serve as fluid inlets and outlets in hydraulic communication with the cylinder ports 37. These ports place cylinder bores 23 in the proper phase through ports 37 during rotation of the cylinder block.
  • cylinder block 20 is designed having an annular recess 40 around shaft 15 in the end of the block adjacent backplate 13.
  • biasing means 41 such as a coil spring axially encircles shaft 15 and exerts a force to bias spider collar 30 toward the swashplate.
  • the force of the spring is transmitted to collar 30 through a mechanical connection comprising washer 42 and push rods 43 which extend through holes provided in the cylinder block.
  • the opposite end of spring 41 is grounded or anchored to shaft 15 by adjustable sleeve 45 which is screwed to the shaft on threads 46.
  • Sleeve 45 is flanged having radial projection against which washer 47 seats through the force of spring 41.
  • Radial projection 50 is provided with slots 51 in its outer face to accommodate the blade of a tool for installation and axial adjustment of sleeve 45.
  • Snapring 48 completes the assembly and engages snapring groove 49 in cylinder body 20 within the recess 40.
  • the inner edge of washer 47 abuts against the rear side of flange 50 and transfers the force of spring 41 to the shaft through sleeve 45 while the outer edge of washer 47 acts to engage snapring 48 to limit axial movement of the cylinder block toward the swashplate.
  • Central recess 40 is shown as having a nonuniform cross section as more fully described in my copending U.S. Pat. application Ser. No. 747,877, entitled Pump or Motor Device, filed July 26, 1968, now U.S. Pat. No. 3,522,759.
  • the central recess is provided with one or more peripheral grooves which allow rod 43 to be radially spaced apart a sufficient distance from the splined connection 22 to provide adequate material strength in the neck of the cylinder block.
  • Sleeve 45 is manually adjusted by advancement on threads 46 until the precise predetermined running clearance between face 38 of the backplate 13 and the face 19 of the cylinder block 20 is set. It can be seen face 38 of the backplate is fixed with reference to face 18 of housing 11, whereas the position of face 19 of the cylinder block is variable depending on the axial position of abutment 50. Cylinder block 21) may be adjusted so that line-to-line contact exists between mating faces 19 and 38 or a few thousandths of an inch clearance may be allowed if desired. Fig. 3 illustrates the maximum separation between surfaces 38 and 19 allowed by the constraining means in exaggerated proportions for clarity. The axial position of collar 45 preset during assembly is maintained during operation by friction holding means. For example, plastic retaining compound may be applied to the mating threads or the threads or sleeve may be mechanically deformed to insure tightness.
  • End plate 13 is bolted onto body 12 completing the assembly.
  • the adjustment of face 19 with respect to face 18 has assured the proper clearance between faces 19 and 38.
  • cylinder block 20 can be precisely positioned with respect to backplate surface 38 by adjustment of sleeve 45 without using a biasing force urging cylinder block onto the backplate.
  • cylinder block 20 is free to move away from collar washer stop 47 and into contact with face 38 of the backplate in response to fluid pressure within bores 23.
  • the axial movement away from face 38 is clearly limited by the position of collar 45.
  • the absence of any mechanical biasing force acting on the cylinder block decreases friction losses and drag and increases pump efficien cy during start-up, low-pressure and all other operating pressure conditions.
  • a gasket may be included during assembly between the backplate and housing to minimize fluid leakage and its width taken into consideration in adjusting sleeve 45.
  • FIG. 2 another preferred embodiment is illustrated.
  • a piston pump or motor unit If is constructed as the device of FIG. 1; however, the means provided for adjusting the axial position of cylinder block 20 are slightly modified, as well as the means for biasing the pistons against the swashplate.
  • adjustability of the axial position of the cylinder block is achieved by shimming against a fixed abutment on the drive shaft.
  • a fixed collar 60 shown as a snapring, is secured to shaft 61 within the recess in cylinder block 20.
  • Snapring 65 is provided in the cylinder block. Encircling drive shaft 61 and abutting snaprings 65 and 60, respectively, are washers 64 and 62. Interposed between washers 64 and 62 are shims 63. It will be seen that the cylinder block is prevented from axial movement toward the swashplate. Snapring 65 in the cylinder block abuts washer 64 which in turn, through shims 63 and washer 62, abuts snapring 60.
  • the force to hold down the piston shoes is exerted by compression springs 71 arranged in annular bores in cylinder block Ztl.
  • the springs 71 extend between snapring 68 on shaft 61 and spherical collar 75.
  • spherical collar 75 is shown as having an extended flanged portion against which the springs seat.
  • Bores 71 which accommodate the biasing springs are shown as being angularly disposed in the cylinder block for compactness and cylinder wall strength, but may be bored parallel to the shaft axis.
  • the utilization of the present invention obviates the necessity of biasing the cylinder block on the backplate by mechanical means.
  • Mechanical force transmitting means act only to bias the cylinder shoes against the swashplate.
  • Cylinder block is constrained, by the supporting engagement of the abutment on the shaft, from axial movement in the direction of the swashplate while remaining free to follow deflections of the backplate to maintain at all operating conditions intimate contact between cylinder block and backplate.
  • the restriction on bidirectional movement along with preadjustment of the relationship of the mating cylinder and backplate surfaces assures that sealing will be achieved automatically during operation by the sizing and positioning of bearing areas of the mating surfaces.
  • the zero bias on the cylinder block decreases friction and drag and increases overall unit efficiency. Further, the required starting torque is reduced by use of the present invention. In motors starting output torque is increased.
  • Another advantage of the present invention is that field disassembly of the unit is facilitated as special press loading equipment is not required for rem-oval of the components within the cylinder block recess.
  • an axial piston hydraulic device including a housing, a shaft rotatable within said housing, a cylinder block having a plurality of axial cylinder bores spaced about the shaft and having associated ports communicating with said bores, a driving connection between said cylinder block and said shaft, said connection allowing for axial adjustment of the cylinder block, a backplate affixed to the housing, said backplate mating with the cylinder block providing properly phased fluid inlet and outlet connections to each cylinder port upon rotation of the cylinder block, pistons having their inner ends disposed within the cylinder bores for reciprocation therein, a spherical collar axially slidable on said shaft, holddown means engaging the outer ends of the pistons, said holddown means being engaged by the slidable collar for pivotal movement about the collar, an inclinable swashplate positioned to operably reciprocate the pistons upon rotation of the cylinder block, means for biasing the pistons toward the swash plate, wherein the improvement comprises:
  • cylinder block constraining means providing free axial movement of the cylinder block adjacent the backplate while constraining the cylinder block to a predetermined maximum separation from the backplate, said constraining means including first abutment means on the cylinder block, and second abutment means on the shaft positioned to effectively engage the first abutment means only at said predetermined maximum separation.
  • An axial piston hydraulic device including a housing, a shaft rotatable within said housing, a cylinder block splined to said shaft for rotation with the shaft and defining a central recess surrounding said shaft, said cylinder block having a plurality of axial cylinder bores spaced about the shaft and having associated ports communicating with said bores, a backplate affixed to the housing, said backplate mating with the cylinder block and providing properly phasedinlet and outlet connections to each cylinder port upon rotation of the cylinder block,
  • pistons having their inner ends disposed within the cylinder bores for reciprocation therein, a spherical collar axially slidable on said shaft, holddown means engaging the outer ends of the pistons, said holddown means being engaged by the spherical collar for pivotal movement about the collar, an inclinable swashplate positioned to operably reciprocate the pistons upon rotation of the cylinder block, wherein the improvement comprises:
  • an adjustable sleeve having a radially projecting flange, said sleeve being in threaded engagement with the shaft to provide axial adjustability;
  • abutment means located within said central recess in said cylinder block
  • An axial piston hydraulic device including a housing, a shaft rotatable within said housing, a cylinder block splined to said shaft for rotation with the shaft, said cylinder block having a plurality of axial cylinder bores spaced about the shaft and having associated ports communicating with said bores, a backplate affixed to the housing, said backplate mating with the cylinder block and providing properly phased inlet and outlet connections to each cylinder port upon rotation of the cylinder block, pistons having their inner ends disposed within the cylinder bores for reciprocation therein, a spherical collar axially slidable on said shaft, holddown means connected to the outer ends of the pistons, said holddown means being engaged by the spherical collar for pivotal movement about the collar, an inclinable swashplate positioned to operably reciprocate the pistons upon rotation of the cylinder block, wherein the improvement comprises:
  • axially rigid adjusting means interposed between said first and second abutment means providing free axial movement of the cylinder block adjacent the backplate while constraining the cylinder block to a predetermined maximum separation from the backplate, said rigid means being axially adjustable to vary said maximum separation.
  • said adjusting means for varying said maximum separation comprises a washer encircling the shaft and at least one shim interposed between said washer and one of said abutments.
  • biasing means comprises spring means disposed in bores in the cylinder block angular with respect to the shaft axis opening into a central recess of the cylinder block and grounded to the shaft by abutment means within said recess.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Hydraulic Motors (AREA)
US753560A 1968-08-19 1968-08-19 Axial piston pump or motor device Expired - Lifetime US3543649A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US75356068A 1968-08-19 1968-08-19

Publications (1)

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US3543649A true US3543649A (en) 1970-12-01

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US753560A Expired - Lifetime US3543649A (en) 1968-08-19 1968-08-19 Axial piston pump or motor device

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US (1) US3543649A (de)
JP (1) JPS5012603B1 (de)
DE (1) DE1929730A1 (de)
FR (1) FR2015868A1 (de)
GB (1) GB1237501A (de)
SE (1) SE347793B (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3803985A (en) * 1970-07-07 1974-04-16 Renault Devices for retaining the sliding shoes of barrel pumps and motors
US3906841A (en) * 1972-08-04 1975-09-23 Linde Ag Axial-piston machine
DE2519933A1 (de) * 1974-05-20 1975-12-04 Karl Marx Stadt Ind Werke Hydrostatische axialkolbenmaschine
US5969269A (en) * 1996-10-10 1999-10-19 Kop-Flex, Inc. Flexible coupling with torque measuring and detecting device
US6073491A (en) * 1998-05-09 2000-06-13 Contitech Luftfedersysteme Gmbh Method and arrangement for making contactless distance and pressure measurements within an air spring
WO2007019313A2 (en) * 2005-08-05 2007-02-15 Differential Dynamics Corporation Variable motion control devices for transmission and other implementations and methods of use thereof

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3803985A (en) * 1970-07-07 1974-04-16 Renault Devices for retaining the sliding shoes of barrel pumps and motors
US3906841A (en) * 1972-08-04 1975-09-23 Linde Ag Axial-piston machine
DE2519933A1 (de) * 1974-05-20 1975-12-04 Karl Marx Stadt Ind Werke Hydrostatische axialkolbenmaschine
US5969269A (en) * 1996-10-10 1999-10-19 Kop-Flex, Inc. Flexible coupling with torque measuring and detecting device
US6073491A (en) * 1998-05-09 2000-06-13 Contitech Luftfedersysteme Gmbh Method and arrangement for making contactless distance and pressure measurements within an air spring
WO2007019313A2 (en) * 2005-08-05 2007-02-15 Differential Dynamics Corporation Variable motion control devices for transmission and other implementations and methods of use thereof
WO2007019313A3 (en) * 2005-08-05 2007-04-19 Differential Dynamics Corp Variable motion control devices for transmission and other implementations and methods of use thereof

Also Published As

Publication number Publication date
JPS5012603B1 (de) 1975-05-13
GB1237501A (en) 1971-06-30
FR2015868A1 (de) 1970-04-30
DE1929730A1 (de) 1970-02-26
SE347793B (de) 1972-08-14

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