US3437015A - Piston type fluid motor having separately fed piston shoes - Google Patents

Piston type fluid motor having separately fed piston shoes Download PDF

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Publication number
US3437015A
US3437015A US679015A US3437015DA US3437015A US 3437015 A US3437015 A US 3437015A US 679015 A US679015 A US 679015A US 3437015D A US3437015D A US 3437015DA US 3437015 A US3437015 A US 3437015A
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United States
Prior art keywords
piston
pressure
motor
fluid
groove
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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
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US679015A
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English (en)
Inventor
Charles A Kubilos
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PepsiAmericas Inc
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Abex Corp
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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
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity

Definitions

  • a fluid motor of the piston type in which the individual pistons have shoes mounted to them for engaging the cam plate, wherein pressure fluid from a common pressure source is supplied through the barrel to an intermediate chamber in each cylinder from which it is permitted to seep at a restricted rate along the piston wall into a groove or chamber in the piston wall adjacent the active or inner end of the piston, from which it is supplied through the piston to the shoe.
  • the low speed performance of the motor is improved by reduction of leakage to tank and reduction of friction due to piston side loads.
  • This invention relates to improved means for supplying pressure fluid to the piston shoes of a fluid motor of the piston type.
  • the conventional piston type fluid motor includes a barrel which is journalled for rotation in the pump casing and connected to drive a shaft.
  • Several piston cylinders or bores are formed in the barrel, and typically although not always these bores are spaced equally and have axes which are parallel to the axis of the barrel.
  • Each bore has a piston which is reciprocable in it.
  • each piston is provided with an element generally called a shoe that facially engages and slides over a cam or swash plate. The plane of the cam plate surface angularly intersects the shaft axis.
  • test data indicates the relatively poor low speed operation of axial piston motors having piston shoes supplied with pressure fluid directly through the piston from the pressure chamber.
  • low speed performance of such motors (below roughly 100 rpm.) has been poorer than would be desired because of excessive leakage of fluid from the pressure chamber at the inner end of the piston through the piston and out from under the piston shoe.
  • the shoes intermittently may tend to lift off the cam surface, and when that occurs a direct path is opened through which fluid is discharged from the piston pressure chamber into the pump casing, which is essentially at tank pressure.
  • This invention is directed to overcoming these disadvantages of prior piston motors, and is predicated upon the discovery of means whereby both leakage and friction are reduced so that low speed operation is significantly improved.
  • the present invention contemplates means for supplyling pressure to the individual piston shoes which does not draw fluid from the piston control chambers, but rather which supplies pressure fluid from a common source to a zone in the cylinder bore from which the fluid is permitted to flow inwardly through a restricted passage between the piston Wall and the cylinder wall, to a groove or recess formed in the piston side wall near to but not opening to the control chamber, and from which a passageway leads internally through the piston into the shoe.
  • pressure is fed to the shoes not through the inner end of the piston, but rather from an entirely separate pressure port in the piston cylinder.
  • the pressure fluid from the port in each bore seeps back along the piston wall to the piston groove, from which it is fed the shoe balance pad. Since the shoe balance pad ordinarily has essentially the same area as the piston, the system is stable only when the piston groove pressure is equal to the control pressure behind the piston; therefore, there is no significant pressure differential between the control chamber at the inner end of the piston, and the piston groove. Hence the discharge of fluid from the control chamber via the shoe is effectively reduced.
  • FIGURE 1 is a diagrammatic illustration of a hydraulic circuit including an axial piston motor, shown in longitudinal section, provided with piston shoe pressure supply means in accordance with a preferred embodiment of the invention
  • FIGURE 2 is an enlarged section of a piston and shoe, showing the piston cocked in its bore;
  • FIGURES 3 and 4 are charts showing the relative magnitudes or profiles of the pressures acting on the upper and lower sides, respectively, of the cooked piston shown in FIGURE 2;
  • FIGURE 5 is a chart showing the relationship between flow and operating speed of a motor of the type shown in FIGURE 1;
  • FIGURE 6 is a chart showing the relationship of flow and the pressure differential between the inlet and outlet ports of the motor.
  • FIGURE 1 the hydraulic circuit shown in FIGURE 1 for purposes of illustration includes a pressure source designated generally by 10 which supplies pressure fluid through an adjustable pressure control valve 11 to a hydraulic motor 12 embodying a preferred form of the structure of this invention.
  • the pressure supply source includes a fluid reservoir or tank and a pump which has an inlet line that receives fluid from tank :15.
  • An electric motor or other prime mover 17 drives pump 16. Excess pressure in the pump outlet or discharge line 18 is spilled to tank 15 by a relief valve 19.
  • valve 11 comprises no part of the invention and may be conventional inasmuch as its function is to adjustably control the pressure and direction of application of pressure fluid from pump .16 to the fluid motor 12.
  • the particular valve 11 shown for purposes of illustration is of the electrically controlled two stage jet tube type valve shown in R. D. Atchley Patent No. 2,884,907, issued may 5, 1959, to which reference may be had for a more complete description. It should be understood that the particular construction of valve 11 is not critical to an understanding of the present motor, and valve 11 can even be a manually operated valve. Valve 11 may be reversible, as shown, to reverse the direction of rotation of motor 12.
  • valve 11 also has a tank port 26 from which a line returns to tank 15.
  • Motor 12 has a casing or tank 27 from which a line returns to tank 15.
  • Motor 12 includes a casing comprised of a generally cylindrical center body portion 35, a port block 36 which is secured and sealed by suitable means at one end of body 35, and an end or head plate 37 mounted at the other end of body portion 35.
  • the motors main ports 24 and 25 are formed in port block 36, and the tank port 27 is formed in body portion 35.
  • End plate 37 and body 35 cooperate to define an internal chamber 38.
  • An annular area 39 is formed within body 35 for receiving a roller bearing 41.
  • This bearing rotatably journals the cylinder barrel 42, which drives a shaft 43.
  • the barrel is loosely connected with the shaft in any suitable manner, such as by means of splines 44. It will be understood that shaft 43 is connected to operate driven means (not shown).
  • the barrel member 42 is spring urged axially of shaft 43 into abutting relation with the port surfaces 46 by a coil spring 47.
  • the port surfaces 46 may be provided on a separate port plate, or may as shown he defined by lands on the inner end of port block 36.
  • the coil spring 47 is compressed between the end of the splined portion of shaft 43 and the inner end of an axial opening 48 formed in barrel 42.
  • Cylinder barrel 42 is provided with a plurality, for example nine, of longitudinally extending cylindrical bores 49. These bores are preferably equally spaced about the circumference of a circle and communicate with corresponding openings 51 extending from the face of the cylinder barrel which abuts the port surfaces 46.
  • the bores 51 are disposed to be brought into alternate registration with arcuate ports 52 and 53 formed in port block 36, which communicate respectively with ports 24 and 25 thereof.
  • Each bore 49 receives a piston 55 for a reciprocating movement within it. Pressure fluid from the inlet port of the port block is admitted into the cylinder bore to cause the piston to be extended when the corresponding barrel port 51 is in registry with that port 52 and 53 of the port block which comprises the inlet port, and fluid is expelled from that port. 51 which is in registry with the outlet port in the port block.
  • Reciprocating movements of pistons 55 are effected by means of a cam assembly 56 mounted upon end plate 37.
  • This cam assembly includes an angulated swash or cam plate 57 carried by plate 37.
  • the angulated cam surface 59 of the swash plate is engaged by hearing shoes 60 mounted by ball and socket joints to the respective ends of the pistons 55.
  • each of the pistons 55 is provided with a spherical head portion 61. This head is received and held within a socket formed in the respective shoe '69.
  • Each of the bearing shoes 68 passes through an opening formed in a retainer or hold-down plate 62. This plate 62 abuts flanges or shoulders 63 formed on the shoes 60 and thereby maintains the shoes in engagement with swash plate 57.
  • the retainer plate 62 is rotatably journalled in a bearing 64 carried by a sleeve 67 which is threaded into an opening in swash plate 57.
  • This opening is formed on angle such that the axis of the opening is perpendicular to the cam surface 59 of the cam plate.
  • the motor may be provided with means for varying the angulation of the cam plate, thereby varying the volume or displacement of the pistons, in known manner.
  • Shaft 43 to which barrel 42 is connected, is rotatably journalled in suitable bearings (not shown) carried by end plate 37.
  • a shoe recess 68 is formed within and bounded by a circumferential land 69 which engages and rides upon the cam surface 59. Pressure fluid is supplied into the recess 68 through an axial bore 71 in the shoe, which communicates at all times with an axial bore 72 formed in the respective piston.
  • the 'bore 72 in the piston communicates, through an angularly extending bore 73, with a recess or circumferential groove 74 formed in the piston side wall adjacent the inner or active end 75 of the piston.
  • the portion of the barrel bore 49 behind (i.e. toward the port block 36) the inner end 75 of the piston constitutes a control chamber 77 pressure in which tends to move the piston outwardly (to the right in FIGURE 1).
  • Groove 74 is separated from the end 75 of the piston, and hence from chamber 77, by a land 78 defined on the piston side wall.
  • Port block 36 of motor 12 has a separate pressure port 80, to which the pressure line 18 of pump 16 is connected. Pressure fluid from port 80 is constantly supplied through a passageway 81 in the port block and a rotating seal at 82 into a short central bore 83 in barrel 42.
  • Branch passages 84 communicate between bore 83 and ports or chambers in the side walls of the respective bores 49.
  • the latter ports are comprised by a circumferential groove 85 formed intermediately in each cylinder bore 49. Groove 85 is preferably positioned so that it is never directly aligned with the piston groove 74, nor does it open directly to the tank chamber 38 when the piston is at its innermost position.
  • a recess can be provided in the piston or line 84 can simply enter bore 49 directly.
  • OPERATION Pressure fluid is continuously supplied from the pressure source 10 to passage 81 in the port block, and through the rotating seal at 82 into each of the branch passages 84 in the barrel and into the respective cylinder bore grooves 85.
  • the pressure in groove 85 is reflected entirely around the piston, and thus of itself imparts no side-wise force to the piston.
  • the pressure fluid in groove 85 flows at a restricted rate between the piston side wall and bore 49, into groove 74 at the inner end of the piston, from which it is applied through bores 73, 72, and 71 into the shoe recess 68.
  • the separate shoe pressure supply system described also establishes fluid pressure force vectors which act on the piston in a manner tending to recenter it when it is cocked or tipped in its cylinder bore. This is best explained by reference to FIG- URES 2, 3, and 4. As shown in exaggerated form in FIGURE 2, when a piston is tilted so that it is in metal-to-metal contact with the bore at one point a at the end of the bore and at an opposite point b on its inner end, different pressure distributions are established between the piston side wall and the cylinder bore on opposite sides of the piston.
  • the pressure drops off more rapidly from a pressure source in the direction of piston divergence from the cylinder wall than it does in the direction of piston convergence with the wall.
  • pressure qualitatively follows the general form of the curve in FIGURE 3.
  • the pressure in chamber 77 is at a value designated as P and from point b rises rather abruptly at piston groove 74, then rises at a decreasing rate to the maximum pressure supplied by the pump P in the vicinity of groove 85. From this level P the pressure drops off along at a gradually decreasing rate, to essentially tank pressure where the piston extends beyond the barrel.
  • the pressure follows the profile shown in FIGURE 4 but acts in the opposite direction.
  • FIGURE 5 of the drawings compares the variation of motor speed as a function of flow through the motor, for a motor having conventional piston shoe feed means directly from the control chamber, with the results obtained in an otherwise similar motor provided with separate piston feed means in accordance with this invention. It can be seen that at low flow rates, below about 1% of maximum, the conventional motor does not rotate at all and virtually all of the flow is wasted as leakage. In contrast, in a motor provided with separately fed piston shoes, rotation begins at a very low flow and thereafter rises essentially in direct proportion to the flow.
  • the differential pressure "between the motor ports 24 and 25 is very different as between a conventional motor and a motor in accordance with this invention.
  • the high friction along the piston walls resulted in a high pressure differential at about 1% flow.
  • the pump began to rotate the differential dropped rapidly to about p.s.i., and then rose gradually as flow increased.
  • the reduction in internal friction was such that the pressure differential remained much more nearly uniform at about 100 p.s.i., over the same region at which the conventional motor did not operate at all or exhibited an undesirably high pressure differential.
  • While the present separate pressure feed means are most useful in improving the operation of motors, they may be also incorporated on pumps of the piston type where, for example, the pump is convertible for use as a motor.
  • a fluid motor of the type having a rotatable barrel with a plurality of pistons reciprocable in bores therein, each piston having a shoe mounted to it for engaging a cam surface
  • each said port being closed at all times by the respective piston
  • each piston having a passage within it for supplying pressure fluid from said recess to the shoe mounted thereon,
  • An axial piston hydraulic motor having a rotatable barrel with a plurality of pistons reciprocable in bores in said barrel, each piston having a shoe mounted to it for engaging a swash plate,
  • each piston and a passage within each piston for supplying fluid from said second groove to the shoe mounted to said piston.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Hydraulic Motors (AREA)
US679015A 1967-10-30 1967-10-30 Piston type fluid motor having separately fed piston shoes Expired - Lifetime US3437015A (en)

Applications Claiming Priority (1)

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US67901567A 1967-10-30 1967-10-30

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US (1) US3437015A (de)
CH (1) CH490611A (de)
DE (1) DE1804529A1 (de)
FR (1) FR1577029A (de)
GB (1) GB1248933A (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3611876A (en) * 1969-08-14 1971-10-12 Ferris Q Day Ultra high-pressure compressible fluid motor
US3726189A (en) * 1971-06-22 1973-04-10 Lucas Industries Ltd Pistons for hydraulic piston type pumps and motors
US3783743A (en) * 1972-11-16 1974-01-08 Abex Corp Axial piston hydraulic transducer shoe retainer structure
US3890882A (en) * 1970-08-03 1975-06-24 Wilfred S Bobier Fluid device having plastic housing and means for mounting a cylinder barrel
US4903578A (en) * 1988-07-08 1990-02-27 Allied-Signal Inc. Electropneumatic rotary actuator having proportional fluid valving
US5230610A (en) * 1989-04-05 1993-07-27 Zahnradfabrik Friedrichshafen Ag Axial piston pump
US5983781A (en) * 1996-09-06 1999-11-16 Sauer Inc. Sliding bearing with self-adjusted load bearing capacity
US6006652A (en) * 1998-10-30 1999-12-28 General Motors Corporation Automotive refrigerant wobble plate type compressor piston with improved ball and socket joint
US6644936B1 (en) * 1999-10-12 2003-11-11 Zexel Valeo Climate Control Corporation Swash plate type refrigerant compressor
US20050147507A1 (en) * 2002-02-13 2005-07-07 Hiroyuki Makino Expander

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1526078A (en) * 1975-09-24 1978-09-27 Mono Pumps Ltd Reciprocating machines
DE2805492C2 (de) * 1978-02-09 1982-10-07 Linde Ag, 6200 Wiesbaden Anordnung zum Kühlen der Kolben bei einer hydraulischen Axialkolbenmaschine
DE3239175C1 (de) * 1982-10-22 1984-03-01 Hydromatik GmbH, 7915 Elchingen Lagerung des triebflansches einer axialkolbenmaschine in schraegachsen-bauart.
DE3416638A1 (de) * 1984-05-05 1985-11-14 Diesel Kiki Co. Ltd., Tokio/Tokyo Taumelscheiben-kolbenpumpe
DE4423023C2 (de) * 1994-06-30 1998-07-09 Brueninghaus Hydromatik Gmbh Axialkolbenmaschine mit einem Kühlkreislauf für die Zylinder und Kolben
DE102004043745B3 (de) * 2004-09-10 2006-02-09 Danfoss A/S Hydraulische Axialkolbenmaschine

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1006269A (en) * 1910-10-17 1911-10-17 Julian F Bentley Engine.
US1274391A (en) * 1915-07-12 1918-08-06 Raynor M Gardiner Hydraulic transmission mechanism.
US1487965A (en) * 1921-01-05 1924-03-25 Anthony G M Michell Rotary reciprocating engine
US3015315A (en) * 1959-09-28 1962-01-02 Tinius Olsen Testing Mach Co Piston-centering means for hydraulic testing machines or the like
US3056358A (en) * 1960-01-20 1962-10-02 United Aircraft Corp Axial piston pump with balanced radial bearing
US3106138A (en) * 1960-06-27 1963-10-08 Hans Toma Piston type hydrostatic power units
US3142262A (en) * 1960-08-31 1964-07-28 Council Scient Ind Res Pressure fluid pistons or plungers
US3153987A (en) * 1960-06-29 1964-10-27 Thoma Hans Piston type hydrostatic power units
US3173376A (en) * 1957-03-21 1965-03-16 United Systems Corp Hydraulic pump or motor

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1006269A (en) * 1910-10-17 1911-10-17 Julian F Bentley Engine.
US1274391A (en) * 1915-07-12 1918-08-06 Raynor M Gardiner Hydraulic transmission mechanism.
US1487965A (en) * 1921-01-05 1924-03-25 Anthony G M Michell Rotary reciprocating engine
US3173376A (en) * 1957-03-21 1965-03-16 United Systems Corp Hydraulic pump or motor
US3015315A (en) * 1959-09-28 1962-01-02 Tinius Olsen Testing Mach Co Piston-centering means for hydraulic testing machines or the like
US3056358A (en) * 1960-01-20 1962-10-02 United Aircraft Corp Axial piston pump with balanced radial bearing
US3106138A (en) * 1960-06-27 1963-10-08 Hans Toma Piston type hydrostatic power units
US3153987A (en) * 1960-06-29 1964-10-27 Thoma Hans Piston type hydrostatic power units
US3142262A (en) * 1960-08-31 1964-07-28 Council Scient Ind Res Pressure fluid pistons or plungers

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3611876A (en) * 1969-08-14 1971-10-12 Ferris Q Day Ultra high-pressure compressible fluid motor
US3890882A (en) * 1970-08-03 1975-06-24 Wilfred S Bobier Fluid device having plastic housing and means for mounting a cylinder barrel
US3726189A (en) * 1971-06-22 1973-04-10 Lucas Industries Ltd Pistons for hydraulic piston type pumps and motors
US3783743A (en) * 1972-11-16 1974-01-08 Abex Corp Axial piston hydraulic transducer shoe retainer structure
US4903578A (en) * 1988-07-08 1990-02-27 Allied-Signal Inc. Electropneumatic rotary actuator having proportional fluid valving
US5230610A (en) * 1989-04-05 1993-07-27 Zahnradfabrik Friedrichshafen Ag Axial piston pump
US5983781A (en) * 1996-09-06 1999-11-16 Sauer Inc. Sliding bearing with self-adjusted load bearing capacity
US6006652A (en) * 1998-10-30 1999-12-28 General Motors Corporation Automotive refrigerant wobble plate type compressor piston with improved ball and socket joint
US6644936B1 (en) * 1999-10-12 2003-11-11 Zexel Valeo Climate Control Corporation Swash plate type refrigerant compressor
US20050147507A1 (en) * 2002-02-13 2005-07-07 Hiroyuki Makino Expander

Also Published As

Publication number Publication date
CH490611A (de) 1970-05-15
DE1804529A1 (de) 1969-07-03
GB1248933A (en) 1971-10-06
FR1577029A (de) 1969-08-01

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