US3698287A - Axial piston device - Google Patents

Axial piston device Download PDF

Info

Publication number
US3698287A
US3698287A US96451A US3698287DA US3698287A US 3698287 A US3698287 A US 3698287A US 96451 A US96451 A US 96451A US 3698287D A US3698287D A US 3698287DA US 3698287 A US3698287 A US 3698287A
Authority
US
United States
Prior art keywords
barrel
shaft
transverse
thrust
housing
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
US96451A
Other languages
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.)
Eaton Corp
Original Assignee
Cessna Aircraft Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Cessna Aircraft Co filed Critical Cessna Aircraft Co
Application granted granted Critical
Publication of US3698287A publication Critical patent/US3698287A/en
Assigned to EATON CORPORATION, EATON CENTER, CLEVELAND, OH 44114-2584, AN OH CORP. reassignment EATON CORPORATION, EATON CENTER, CLEVELAND, OH 44114-2584, AN OH CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: CESSNA AIRCRAFT COMPANY, THE
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • 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
    • F01B3/0032—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
    • F01B3/007—Swash plate
    • F01B3/0073—Swash plate swash plate bearing means or driving or driven axis bearing means

Definitions

  • This invention relates generally to axial piston fluid pumps and motors, and more particularly to improved means for supporting the rotating cylinder barrel of such units against transverse side loads experienced during operation.
  • Axial piston units of this class include a rotary cylinder barrel having a flat face in abutment with a stationary valve face, and a plurality of axial bores adapted to receive reciprocating pistons that engage an adjacent inclined cam surface.
  • the cylinder barrel mounts upon a drive .shaft for transverse support and for rotation therewith. It is important that support for the cylinder barrel against this side load be so arranged that no tilting moments are induced upon the barrel, as the barrel must remain in flat engagement with the valve face for proper unit operation. If the cylinder barrel tilts or cocks slightly, the fluid bearing between the valve face and barrel may lift the barrel completely off the valve face to cause galling or possibly destruction of the entire unit.
  • 2,642,810 typical of the prior art, assures alignment of the side load and its support by use of a crowned spline driving connection and support between the barrel and shaft.
  • the spline connection is somewhat loose and crowned or rounded to permit, to a limited degree, universal movement of the barrel relative to the shaft.
  • the cylinder barrel support is at the crest of the crown, and the unit is designed to position the crest in line with the transverse side load.
  • a flat, straight and uncrowned driving connection between the cylinder barrel and drive shaft supports the barrel against its side loads.
  • the driving connection extends inwardly toward the valving from the edge of the cylinder barrel adjacent the cam surface.
  • the driving connection supports the barrel at this outer edge at a plane aligned with the transverse side loads imposed on the cylinder barrel during operation.
  • the shaft is supported so that upon deflection the point of maximum deflection is between the face of the cylinder barrel engaging the valve face and the axial midpoint of the driving connection.
  • the support location remains at the barrel outer edge aligned with the side load even as the shaft deflects.
  • Yet another object in accordance with thepreceding objective is to provide a structure whereby the cylinder barrel is supported on an axial driving connection on the shaft at its end opposite that which engages the valve face, and wherein the location of maximum shaft deflection is between the axial midpoint of the driving connection and the valve engaging end of the cylinder barrel.
  • a further object is to provide a flat tooth, uncrowned spline connection between the cylinder barrel and drive shaft in accordance with the preceding objectives.
  • FIG. 1 is an offset transverse section of an axial piston unit incorporating the present invention
  • FIG. 2 is a section view taken along line 2-2 of FIG.
  • FIG. 3 is a diagram and partial section similar to FIG. 1 showing in exaggeration the present invention under load
  • FIG. 4 is a partial section taken along line 4-4 of FIG. 3;
  • FIG. 5A is a flat projection of a circular section taken along line 5-5 of FIG. 4;
  • FIG. 5B is a view similar to FIG. 5A of a device not using the present invention.
  • the axial piston unit of FIG. 1, utilizable either as a pump or motor, is generally designated by the numeral 10.
  • the unit has a two-piece outer housing, a hollowed casing 11 firmly secured to fluid porting backplate 12
  • Drive shaft 13 extends axially into the housing, being supported at bearings 14 and 15 in the casing and backplate respectively, with one end 16 projecting outwardly for rotary driving connection with a prime mover in the case of pump operation or with a work performing device if the unit operates as a motor.
  • a tiltable cam plate 17 has trunnions (not shown) journalled to the casing 11 in a plane at right angles to the drive shaft axis.
  • Cylinder barrel 18 mounts for driving connection and radial support upon shaft 13 at spline 19.
  • spline comprises inter-engaging, axially flat, straight teeth of involute form on both the barrel and shaft.
  • Face 21 has a pair of arcuate valve slots 22 and 23, FIG. 2, communicating with fluid inlet and outlet ports 24, 25 in the stationary backplate.
  • A'fluid bearing is maintained between the faces 20, 21 to lubricate same and provide barrel axial support.
  • ports 26 Upon rotation of the cylinder barrel, ports 26 alternately register with valve slots 22, 23 to deliver and receive fluid therefrom.
  • Each barrel port 26 opens into an axial bore 27, which bores 27 are symmetrically disposed about the shaft axis. Bores 27 reciprocally carry working pistons 28 whose spherically formed ends 29 protrude outwardly of the barrel toward cam plate 17.
  • Swaged for pivotal movement on piston sphere ends 29 are slipper shoes 30 which directly abut the inclined cam surface.
  • the piston shoes 30 extend through openings in a unitary retainer or spider plate 33 which has a central spherical socket accepting the spherical outer surface of a pivot 34.
  • Thrust force indicated by arrow 31, directed through the center of ball end 29 and perpendicular to the cam surface, urges piston 28 inwardly upon cylinder barrel rotation.
  • This thrust can be resolved into an axial component acting along the piston axis and a transverse component 32 perpendicular to the piston axis. This latter component is the side load imposed on the unit and constitutes the driving torque transmitted between the pistons and cylinder barrel.
  • Spring in the central bore of the cylinder barrel acts through a plurality of pins 36, symmetrically disposed about the shaft axis, to bias the pivot 34 and spider plate 33 rightwardly.
  • the spring force is transmitted through shoes 30 and to urge pistons 28 outwardly toward the inclined cam surface.
  • Spring 35 is oppositely grounded to the shaft by snap ring 37.
  • Pins 36 are located radially inwardly of the cylinder barrel, passing axially through the driving connection at the spline area.
  • Each pin 36 (two are shown in FIG. 4) is located in an opening formed by the absence of a spline tooth on the cylinder barrel, or alternately, in a space formed by deleting a shaft spline tooth.
  • the straight spline configuration as contrasted to usual crowned splines, permits easy insertion of the force transmitting pins into their respective openings.
  • Strength of the forwardly extending neck portion of the barrel is greatly increased by situating pins 36 in the spline area rather than through the neck portion proper.
  • resultant side load 41 varies slightly during unit operation as the number of pistons on pressure varies as when one piston chamber leaves pressure stroke and another comes on pressure; however, averaged over a full revolution of the cylinder barrel, the resultant of side force 41 will be as shown.
  • the outer edge 42 of the barrel is positioned in plane 38 in direct alignment with side force 41.
  • Plane 38 thus becomes the rightward end of the axial extent of driving connection 19, the leftward end being at the end 43 of the shaft spline teeth.
  • the driving connection is defined in axial extent as that distance over which the spline teeth of the shaft and cylinder barrel inter-engage.
  • the shaft 13 deflects or bends downwardly under the action of transverse thrust 41 as shown in greatly exaggerated proportions in FIG. 3.
  • the supports for shaft 13, bearings 14 and15, the location of the spline and diameter of the shift, or diameters in the case of a stepped shaft, are so selected that maximum shaft bending occurs at the plane denoted 44.
  • Maximum deflection plane 44 is inside or to the left of the inner driving connection end 43, between end 43 and cylinder block end 20. To the right of plane 44, therefore, the shaft continuously curves upwardly, keeping the cylinder barrel support located at the right edge 42 and plane 38.
  • Cylinder barrel 18 slides transversely downwardly, from its original position shown by the dashed lines, but does not tilt since its support remains in alignment with transverse force 41.
  • the spline connection 19 provides sufficient diametral clearance to permit the slight relative movement between cylinder barrel and shaft, the difference between the perpendicular cylinder barrel movement and the angular bending of shaft 13 about plane 44.
  • the effective length of the shaft spline that is the length extending inward from the outer edge of the barrel, should be held to the minimum within good design practice to accommodate the imposed torque loading. In this way, the necessary diametral clearance permitting relative movement can also be held to a minimum inasmuch as increased spline length requires increased clearance for barrel movement.
  • FIGS. 4 and 5A clearly illustrate the manner in which the support point remains aligned with the transverse load at edge 42.
  • the barrel side load is supported primarily by the right side of the spline, whose teeth engage as shown at plane 38.
  • FIG. 5A is a flat projection axial view of the mating teeth 45 and 46 of the drive shaft and cylinder barrel.
  • the uncrowned shaft teeth 45 curve upwardly from maximum deflection plane 44, and they engage the cylinder barrel and support same only at the outer edge 42.
  • the shaft spline teeth cock slightly relative to the cylinder barrel under load 41, they remain in supporting engagement only at edge 42.
  • FIG. 5B illustrates operation of a device in which the maximum deflection plane 44' is not properly located intermediate the driving connection midpoint and cylinder block valving end in accordance with the present invention.
  • Maximum deflection plane instead is located to the right of the axial center of the spline driving connection.
  • the shaft and its straight teeth 45 curve upwardly in both directions from plane 44 such that, dependent upon the form of the bending curve, engagement between teeth 45, 46 occurs at either or both ends of the driving connection or somewhere intermediate. Accordingly, transverse support for the barrel noted by arrow 47 shifts, for instance, to end 43.
  • the misalignment of support 47 and load 41 induces a couple upon the cylinder barrel cocking barrel end relative to valve face 21. It will be apparent that if the plane 44 of maximum deflection is to the right side of barrel end 42 in FIG. 5A, barrel support shifts to the opposite end 43 of the driving connection and produces a moment on the cylinder block.
  • valve slots 22, 23 of FIG. 2 It is many times advantageous in various unit designs to alter the position of the valve slots 22, 23 of FIG. 2 from their symmetric disposition shown. For instance, it may be desirable to skew or rotate the pressure slot, for instance slot 23, slightly counterclockwise so that there is greater area above than below center line 48. This also alters the location of transverse load 41, shifting plane 38 to intercept the shaft axis slightly left of point 39 where piston sphere end plane 40 intercepts the shaft axis. Itwill be readily apparent that skewing slot 23 clockwise will move load 41 and its plane 38 rightwardly of point 39. By taking into consideration the valve slot position, the unit may be properly designed such that cylinder block end 42 is properly aligned with transverse load 41, whether or not same is in line with the point 39 defined by the piston sphere end plane.
  • transverse load 41 may also alter slightly dependent upon rotational speed and operating pressure of the unit. Designing the unit to locate the cylinder block edge 42 at the position of transverse load 41 when the unit is operating under its normal or most average conditions will provide consistent, reliable and longer unit operation. Though perfect alignment of load 41 and barrel edge 42 cannot be maintained under all conditions, the above outlined approach to determining the usual transverse load location and locating the barrel to same will attain optimum results.
  • an axial piston device having a housing provided with valve means and fluid inlet and outlet ports at one end, an inclined or inclinable cam plate at the opposite end of the housing; a drive shaft extending axially in the housing; a cylinder barrel mounted intermediate the housing ends in driving relation with the shaft and positioned having an inner end face in flat surface contact with said valve means, said barrel having a plurality of axial bores; pistons reciprocally mounted in said bores having spherical outer ends in driving relation with the cam plate so as to transmit transverse thrust to said cylinder barrel upon rotation of said barrel; improved means for supporting said barrel against said transverse thrust, comprising:
  • said shaft being supported within the housing such that the point of maximum transverse shaft deflection is intermediate said barrel end face and the axial midpoint of the mating portions of said driving connections, whereby upon deflection of said shaft, said barrel remains supported on the shaft at said barrel outer end and said transverse thrust plane, and said end face remains in flat surface contact with the valve means.
  • the device of claim 5 further comprising biasing means located in a central bore of said barrel intermediate said barrel transverse end face and said spline connection; pivot means positioned forwardly of said barrel in a direction toward said cam plate and having an outer spherical surface, force transmitting means extending from said spring means freely through said 7 8 spline to contact said pivot, a piston retainer plate slipper shoes pivotally attached to said piston sphere pivotal on said pivot spherical surface, and a force ends engaging said inclined cam surface whereby transmitting connection between said retainer plate upon rotation of said barrel thrust is transmitted to and pistons whereby said spring biases said pistons said barrel in a direction perpendicular to said toward said cam plate.
  • mitting connection comprises a plurality of pins a flat tooth spline connection between said barrel disposed about the drive shaft axis extending through and Sald Shaft at a S c PPOS IZC end of the baropenings formed between teeth of said spline connecfel, Sald splme y Supporting Sald barrel i 10 against the transverse component of said thrust;

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
US96451A 1970-12-09 1970-12-09 Axial piston device Expired - Lifetime US3698287A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US9645170A 1970-12-09 1970-12-09

Publications (1)

Publication Number Publication Date
US3698287A true US3698287A (en) 1972-10-17

Family

ID=22257400

Family Applications (1)

Application Number Title Priority Date Filing Date
US96451A Expired - Lifetime US3698287A (en) 1970-12-09 1970-12-09 Axial piston device

Country Status (5)

Country Link
US (1) US3698287A (enExample)
CA (1) CA938495A (enExample)
DE (1) DE2160934A1 (enExample)
FR (1) FR2117531A5 (enExample)
GB (1) GB1370474A (enExample)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3890882A (en) * 1970-08-03 1975-06-24 Wilfred S Bobier Fluid device having plastic housing and means for mounting a cylinder barrel
US4269574A (en) * 1978-04-03 1981-05-26 Bobier Wilfred S Fluid device
US5784949A (en) * 1997-06-25 1998-07-28 Sauer Inc. Retaining system for slipper holddown pins
US6048183A (en) * 1998-02-06 2000-04-11 Shurflo Pump Manufacturing Co. Diaphragm pump with modified valves
US20030010195A1 (en) * 2000-06-08 2003-01-16 Rainer Stolzer Axial piston engine
US20030091440A1 (en) * 2001-11-12 2003-05-15 Patel Anil B. Bilge pump
US6623245B2 (en) 2001-11-26 2003-09-23 Shurflo Pump Manufacturing Company, Inc. Pump and pump control circuit apparatus and method
US7083392B2 (en) 2001-11-26 2006-08-01 Shurflo Pump Manufacturing Company, Inc. Pump and pump control circuit apparatus and method

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3890882A (en) * 1970-08-03 1975-06-24 Wilfred S Bobier Fluid device having plastic housing and means for mounting a cylinder barrel
US4269574A (en) * 1978-04-03 1981-05-26 Bobier Wilfred S Fluid device
US5784949A (en) * 1997-06-25 1998-07-28 Sauer Inc. Retaining system for slipper holddown pins
US6048183A (en) * 1998-02-06 2000-04-11 Shurflo Pump Manufacturing Co. Diaphragm pump with modified valves
US20030010195A1 (en) * 2000-06-08 2003-01-16 Rainer Stolzer Axial piston engine
US6796774B2 (en) * 2000-06-08 2004-09-28 Brueninghaus Hydromatik Gmbh Axial piston engine
US20030091440A1 (en) * 2001-11-12 2003-05-15 Patel Anil B. Bilge pump
US6715994B2 (en) 2001-11-12 2004-04-06 Shurflo Pump Manufacturing Co., Inc. Bilge pump
US7806664B2 (en) 2001-11-12 2010-10-05 Shurflo, Llc Bilge pump
US6623245B2 (en) 2001-11-26 2003-09-23 Shurflo Pump Manufacturing Company, Inc. Pump and pump control circuit apparatus and method
US7083392B2 (en) 2001-11-26 2006-08-01 Shurflo Pump Manufacturing Company, Inc. Pump and pump control circuit apparatus and method

Also Published As

Publication number Publication date
GB1370474A (en) 1974-10-16
FR2117531A5 (enExample) 1972-07-21
CA938495A (en) 1973-12-18
DE2160934A1 (de) 1972-06-29

Similar Documents

Publication Publication Date Title
US3319575A (en) Piston
US4602554A (en) Axial piston machine, more particularly axial piston pump of the inclined disc or skew axis type
CA1297342C (en) Radial piston pump and motor
US3657970A (en) Hydraulic pump or motor having a rotary cylinder barrel
US3255706A (en) Rotary radial piston machines with tangential balancing recesses for the pressure balance of the pistons
US3175510A (en) Variable displacement pump
US3131539A (en) Hydraulic transmission
WO2007060822A1 (ja) 斜軸式可変容量型ポンプ・モータ
US3698287A (en) Axial piston device
US3139037A (en) Hydraulic apparatus
US3265008A (en) Hydraulic apparatus
US3046906A (en) Means for counteracting centrifugal force moments in rotary cylinder barrel engines
US3191543A (en) Pump or motor device
US3486454A (en) Piston pump with remote control of displacement
US3382793A (en) Axial piston hydraulic unit
US3611879A (en) Axial piston device
US3010405A (en) Pump or motor device
US4426914A (en) Axial piston pump
US6196109B1 (en) Axial piston pump and improved valve plate design therefor
US3011453A (en) Hydraulic apparatus
US3253551A (en) Axial piston unit
US3405646A (en) Hydraulic pumps or motors
US3255673A (en) Axial piston hydraulic units
US3468263A (en) Power transmission
US3356037A (en) Reciprocating pistons for pumps and motors

Legal Events

Date Code Title Description
AS Assignment

Owner name: EATON CORPORATION, EATON CENTER, CLEVELAND, OH 441

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CESSNA AIRCRAFT COMPANY, THE;REEL/FRAME:004991/0073

Effective date: 19880930