US3727521A - Rotary pump with displacement control - Google Patents

Rotary pump with displacement control Download PDF

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Publication number
US3727521A
US3727521A US00133278A US3727521DA US3727521A US 3727521 A US3727521 A US 3727521A US 00133278 A US00133278 A US 00133278A US 3727521D A US3727521D A US 3727521DA US 3727521 A US3727521 A US 3727521A
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United States
Prior art keywords
cylinder block
fluid
port
swashplate
pistons
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
US00133278A
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English (en)
Inventor
R Reynolds
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Sundstrand Corp
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Sundstrand Corp
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Publication date
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Publication of US3727521A publication Critical patent/US3727521A/en
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Classifications

    • 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
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/26—Control
    • F04B1/30—Control of machines or pumps with rotary cylinder blocks
    • F04B1/32—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block
    • F04B1/324—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block by changing the inclination of the swash plate
    • 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
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
    • F04B1/2014—Details or component parts
    • F04B1/2042—Valves

Definitions

  • ABSTRACT An axial piston pump including a rotary cylinder block with reciprocable pistons controlled by an adjustable swashplate for varying displacement as the cylinder block rotates against a valve plate, together with a control port in the valve plate for supplying fluid under pressure to the pumping pistons for controlling the position of the swashplate and therefore the displacement through the medium of the pumping pistons rather than separate control means.
  • an axial piston device may include a housing comprised of two or more housing portions suitably joined, a cylinder block rotatable in the housing with axially disposed pistons reciprocable in fluid chambers under control of a cam or swashplate as the cylinder block rotates against a valve plate having inlet and outlet ports communicable serially with the fluid chambers.
  • Controls may include a constant biasing means acting on the displacement varying member in a manner to urge it into stroke or out of stroke, and a variable bias control may be applicable in opposition to the constant bias in order to overbalance or underbalance the latter selectively in a manner to vary displacement according to some desired principle.
  • a constant pressure control may utilize a spring biasing force urging the swashplate into stroke, and a piston and cylinder device for urging the swashplate out of stroke under control of a valve responsive to discharge pressure in a manner effective to maintain constant discharge pressure.
  • control piston and cylinder device and the linkages associated with it often require precise manufacture and often are fragile so that the control becomes a critical factor in the unit controlling both the cost of manufacture and the durability.
  • porting in order to conduct control pressure from the pump outlet to the control valve, and the control piston and cylinder device, the porting must pass through one or more joints at the juncture of housing members which gives rise to potential leakage problems.
  • the present invention has for its general object a simplification of control means in variable displacement hydraulic units by utilizing the main pistons to control displacement.
  • variable displacement cam controlling the stroke of the pistons is subjected to a displacement varying force by application of control fluid to the main pistons, thereby eliminating the need for a separate control piston and cylinder device of expensive and fragile construction.
  • the principles of the invention are demonstrated in connection with an axial piston pump with a cam or swashplate mounted for pivotal adjustment about an axis generally transverse to the axis of the rotary cylinder block.
  • axial pistons are reciprocated by the swashplate at one end of the cylinder block, while the piston chambers successively communicate with inlet and outlet ports in a valve plate at the opposite end of the cylinder block.
  • the valve plate includes a control port located between the inlet and outlet ports and adapted to supply control fluid successively to the pistons as they pass the control port, thereby to apply a force for varying the angle of the swashplate.
  • the swashplate is biased in a stroke increasing direction and the control port is utilized to supply fluid for biasing the swashplate in a stroke reducing direction.
  • Fluid is supplied to the control port under control of a valve responsive to outlet pressure and adapted to function in a way to control the swashplate to maintain the outlet pressure constant.
  • the control port is centrally located between the outlet port and the inlet port and spaced from each by an amount approximately equal the length of each cylinder block port so that the control port is always in communication with one of the cylinder ports, and the size of the control port is such that it primarily communicates with only one cylinder port.
  • the inlet and outlet ports in the valve plate have a greater length at one side of the swashplate pivot axis in order to utilize the pumping pistons to urge the swashplate into stroke.
  • other means may be used for urging the swashplate into stroke.
  • FIG. 1 is a diagrammatic illustration of a pump together with control circuit embodying the principles of the present invention.
  • FIG. 2 is a sectional view taken at about the line 22 in FIG. 1, showing the arrangement of the control port in the valve plate.
  • the invention is illustrated in connection with a pump generally designated 10 which may be of the type described in US Pat. Nos. 3,366,072 and 3,366,968, if desired, but the invention is not limited to use with such pump constructions.
  • the pump is illustrated diagrammatically as including a rotatable cylinder block appropriately mounted in bearings as at 12 for rotation about a longitudinal central axis 13.
  • the cylinder block is formed with an annular series of axially disposed fluid chambers 15 arranged around the axis of rotation and each including a reciprocable piston as at 17.
  • an adjustable cam or swashplate 18 mounted for pivotal movement about an axis 19 transverse to cylinder block axis 13.
  • the swashplate is formed with one or more arcuate bearing surfaces as at 20 supported on roller bearings 21 in an arcuately curved bearing race 22.
  • the face of the swashplate 18 at 25 supports an annular bearing ring 26.
  • the bearing ring includes a plurality of sockets for universally receiving the spherical ends 28 of a plurality of piston rods 29 having opposite spherical ends 30 universally mounted in the pistons 17 respectively.
  • Attached to the bearing ring 26 is a timing member 32 which allows limited pivotal movement of the connecting rods 29 but essentially maintains the rods generally perpendicular to the bearing ring so that as the cylinder block rotates, the bearing ring rotates with the block.
  • the timing member 32 is piloted on a spherically shaped member 34 appropriately mounted on the cylinder block 1 1, all as described in more detail in the aforementioned U. S. Pat. Nos. 3,366,072 and 3,366,968.
  • the cylinder block rotates against the face of a stationary valve plate 36 appropriately mounted in a suitable housing with the remaining pump structure and including ports for supplying fluid to and from the pump chambers through cylinder ports 37 which lead from the chambers 15 to the end of the cylinder block.
  • the port plate 36 includes an arcuate inlet port 38 and a similarly shaped arcuate outlet port 39 symmetrically disposed in the plate at opposite sides of a piston dead center axis 40 which extends generally transverse to the cylinder block axis and transverse to the swashplate pivot axis and lies in the plane passing through the angular positions where the pistons reach opposite ends of their strokes.
  • the swashplate 18 is mounted to pivot about an axis (19) which is transverse to the cylinder block axis and which intersects the cylinder block axis perpendicular thereto and perpendicular to a timing axis coincident with the piston dead center axis 40 and centrally disposed between the inlet and outlet ports 38 and 39.
  • the swashplate is biased in a stroke increasing direction by arrangement of the arcuate ports 38 and 39 with a greater length above the pivot axis 19 than below, so that the pumping pistons exposed to high pressure in the port 39 exert a greater force on the swashplate above the axis 19 than below the axis 19.
  • the swashplate is normally biased into stroke by use of the main pumping pistons without other additional structure, as a result of which the pump is simplified, the cost is reduced, and life is prolonged.
  • other means may be employed separately or in combination with the arrangement described for purposes of biasing the swashplate into stroke.
  • the swashplate pivot axis 19 may be lowered from the transverse center line through the port plate, and such arrangement will have the effect of increasing the length of the arcuate port 39 above the pivot axis in a way such that the pumping pistons exert a stroke increasing influence on the swashplate.
  • the swashplate may be urged in a stroke increasing direction through the medium ofa suitable spring mechanism applying a constant bias along the lines of that illustrated in the aforementioned U. S. Pat. Nos. 3,366,072 and 3,366,968.
  • the present invention contemplates application of a control force through the medium of the main pumping pistons by subjecting the latter to control fluid under pressure.
  • the port plate 36 is formed with a control port 42 located in the path of the cylinder ports 37 and located centrally between the end 39a of the outlet port 39 and the beginning 38a of the inlet port 38.
  • the cylinder block rotates counterclockwise in the direction of the arrow 43.
  • the piston 17 therein may be subjected to control fluid under pressure to apply a stroke decreasing force.
  • the control port is spaced from the adjacent ends of the ports 38 and 39 by an amount equal to the length of cylinder ports 37 so that one port 37 is substantially always exposed to control fluid under pressure and only one at a time is exposed.
  • a supply of fluid under pressure to the control port 42 is controlled by a constant pressure control valve as at which may be of the type described in US. Pat. No. 3,465,680 if desired.
  • the circuit may include a solenoid depressurization valve as at 51 which may be of the type described in U. S. Pat. No. 3,563,675.
  • the pump outlet port 39 communicates with a discharge conduit 53, and branch conduit 54 communicates discharge pressure to the constant pressure control valve 50.
  • the latter includes a valve member 55 having enlarged lands 56 and 57 with a reduced stem portion 58 therebetween.
  • the end of the valve member 55 is formed with a large disc 59 which provides a spring seat for a coil spring 61 in a spring chamber 62 where the spring is grounded at the end of the chamber.
  • the valve 50 includes a port 66 normally closed by land 56 and a port 67 normally closed by land 57 when the spring 61 biases the valve member toward the left as viewed in FIG. 1.
  • the ports 66 and 67 communicate with a passage 68 leading to the control port 42.
  • the swashplate In operation, the swashplate is normally biased into stroke as described above so that on rotation of the cylinder block, the pump delivers fluid under pressure to the discharge conduit 53.
  • the valve 50 senses discharge pressure through the conduit 54, and when the pressure rises unduly, the valve stem 55 is moved to the right against the bias of spring 61, admitting fluid under pressure past the land 57 to the port 67 and the control port 42 to reduce pump displacement.
  • movement of the valve member 55 toward the right also communicates port 66 with drain port 69 through the reduced stem portion 58 in a way to reduce the effect of the correction called for by the pressure response of the valve.
  • the depressurization valve 51 includes a valve stem 70 with a reduced stern portion 71 between enlarged portions 72 and 73.
  • the valve member is normally positioned as illustrated in FIG. 1 so that the enlarged portion 72 blocks a high pressure passage 54a and communicates a control port 74 with a drain port 75 leading to a conduit 76 which in turn connects with an inlet conduit 77 leading to the pump inlet port 38.
  • the valve stem 70 may be moved to the right as viewed in FIG. 1 by means such as a selectively energizable solenoid to a position where the drain port 75 is blocked by the enlarged stem portion 73, and the pressure port 54a is communicated with the control port 74 through the reduced stem portion 71.
  • the end of discharge port 39 may be shortened at 39a and the beginning of inlet port 38 may be lengthened at 3811 so that the control port is centrally disposed between the port ends and spaced therefrom by an amount approximately corresponding to the length of cylinder ports 37.
  • a rotary fluid translating apparatus comprising, a rotary cylinder block having a plurality of fluid chambers angularly spaced around the axis of rotation of the block, a plurality of pistons reciprocable in the fluid chambers, a cam disposed relative to the cylinder block for causing reciprocation of the pistons as the cylinder block rotates, means mounting the cam for adjustment to vary the stroke of the pistons, means biasing the cam in one direction, a port plate adjacent the cylinder block having inlet and outlet ports, ports in the cylinder block communicating the fluid chambers successively with the inlet and outlet ports as the cylinder block rotates, a control port in the port plate for supplying fluid under pressure successively to the fluid chambers as the cylinder block rotates to apply a force through the pistons to the cam in opposition to the biasing means for controlling the position of the. cam, and selectively operable means for supplying control fluid under pressure to the control port.
  • a rotary fluid translating apparatus as defined in claim 1, including means biasing the cam in a direction to cause the pistons to stroke when the cylinder block rotates, and means locating the control port to supply fluid under pressure to the pistons while positioned to bias the cam in a stroke reducing direction.
  • An axial piston pump comprising, a rotatable cylinder block having an annular series of axially disposed fluid chambers spaced around the axis of the cylinder block, piston means reciprocable in the fluid chambers and projecting from one end of the cylinder block, a cam disposed adjacent said one end of the cylinder block for causing reciprocation of the piston means as the cylinder block rotates, a valve plate engaging the other end of the cylinder block, inlet and outlet ports in the valve plate for admitting low pressure fluid and exhausting high pressure fluid, ports in the end of the cylinder block communicating the chambers successively with the inlet and outlet ports as the cylinder block rotates, means mounting the cam for pivotal adjustment to vary the stroking of the piston means as the cylinder block rotates, means biasing the cam in a direction to increase stroking of the piston means, and a control port in the valve plate between the outlet port and the inlet port for successive communication with the chambers as the block rotates to supply control fluid to successive piston means to bias the cam in a stroke
  • a pump as defined in claim including conduit means for supplying control fluid under pressure to the control port, and selectively operable valve means in the conduit means for controlling the flow of control fluid to the control port.
  • valve means is responsive to increase in outlet pressure to reduce displacement.
  • An axial piston pump comprising, a rotatable cylinder block having an annular series of fluid chambers spaced around the axis of the cylinder block, piston means reciprocable in the fluid chambers, a swashplate disposed adjacent one end of the cylinder block for causing reciprocation of the pistons as the cylinder block rotates, means mounting the swashplate for pivotal adjustment about an axis generally transverse to the axis of the cylinder block to vary the stroke the cylinder block, arcuate inlet and outlet ports in the valve plate at opposite sides ofa piston dead center axis generally transverse to the cylinder block axis and the swashplate pivot axis for admitting and exhausting fluid, ports in the end of the cylinder block communicating the chambers successively with the inlet and outlet ports as the cylinder block rotates, said arcuate inlet and outlet ports including a greater length at one side of the swashplate pivot axis so that the swashplate is biased by the pistons in a direction to increase piston stroke, and
  • control port is located centrally between adjacent ends of the outlet port and inlet port.
  • a pump as defined in claim 9 wherein the space of the pistons, a valve plate engaging the other end of between the control port and each of the inlet and outlet ports corresponds to the length of each cylinder port.
  • An axial piston pump comprising, a rotatable cylinder block having an annular series of axially disposed fluid chambers spaced around the axis of the cylinder block, piston means reciprocable in the fluid chambers and projecting from one end of the cylinder block, a swashplate disposed adjacent said one end of the cylinder block for causing reciprocation of the piston means as the cylinder block rotates, a valve plate engaging the other end of the cylinder block, arcuate inlet and outlet ports in the valve plate for admitting and exhausting fluid, ports in the end of the cylinder block communicating the chambers successively with the inlet and outlet ports as the cylinder block rotates, means mounting the swashplate for pivotal movement about an axis generally transverse to the axis of rotation of the cylinder block, means biasing the swashplate in a direction to cause stroking of the piston means as the cylinder block rotates, a control port in the valve plate between the inlet and outlet ports for successive communication with the chambers as the block rotates, conduit
  • control port is centrally located between adjacent ends of the outlet port and inlet port and spaced therefrom by an amount corresponding to the length of each cylinder port.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Hydraulic Motors (AREA)
US00133278A 1971-04-12 1971-04-12 Rotary pump with displacement control Expired - Lifetime US3727521A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US13327871A 1971-04-12 1971-04-12

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US3727521A true US3727521A (en) 1973-04-17

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US00133278A Expired - Lifetime US3727521A (en) 1971-04-12 1971-04-12 Rotary pump with displacement control

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US (1) US3727521A (de)
JP (1) JPS5520072B1 (de)
DE (1) DE2217891A1 (de)
FR (1) FR2132869B1 (de)
GB (1) GB1363990A (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3999466A (en) * 1973-06-30 1976-12-28 Eckhard Aschke Hydrostatic pump/motor unit
US4631000A (en) * 1984-07-16 1986-12-23 Sundstrand Corporation Variable displacement hydraulic pressure intensifier
FR2725759A1 (fr) * 1994-10-17 1996-04-19 Caterpillar Inc Module hydraulique a pistons axiaux a course variable
DE4396844C2 (de) * 1992-12-22 1998-05-07 Komatsu Mfg Co Ltd Vorrichtung zur Steuerung von Druck in den Zylinderkammern von hydraulischen Pumpen und Motoren
US6361285B1 (en) 1998-12-22 2002-03-26 Parker Hannifin Gmbh Valve plate with hydraulic passageways for axial piston pumps
US6705203B2 (en) 2001-11-28 2004-03-16 Sauer-Danfoss Inc. Extended male slipper servo pad arrangement for positioning swashplate and method assembling same
EP2933485A1 (de) 2014-04-17 2015-10-21 Danfoss Power Solutions GmbH & Co. OHG Hydraulikpumpe mit verstellbarer fördermenge
US11592000B2 (en) 2018-07-31 2023-02-28 Danfoss Power Solutions, Inc. Servoless motor

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4653986A (en) * 1983-07-28 1987-03-31 Tidewater Compression Service, Inc. Hydraulically powered compressor and hydraulic control and power system therefor
JPH01305259A (ja) * 1988-06-03 1989-12-08 Matsushita Electric Ind Co Ltd 給湯機
DE102022107860A1 (de) 2022-04-01 2023-10-05 Danfoss Power Solutions Inc. Hydraulische Axialkolbeneinheit und Verfahren zum Steuern einer hydraulischen Axialkolbeneinheit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3190232A (en) * 1963-02-11 1965-06-22 Budzich Tadeusz Hydraulic apparatus
US3199461A (en) * 1963-05-27 1965-08-10 Cessna Aircraft Co Hydraulic pump or motor
US3230894A (en) * 1962-11-05 1966-01-25 Benjamin W Badenoch Power transmission

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3230894A (en) * 1962-11-05 1966-01-25 Benjamin W Badenoch Power transmission
US3190232A (en) * 1963-02-11 1965-06-22 Budzich Tadeusz Hydraulic apparatus
US3199461A (en) * 1963-05-27 1965-08-10 Cessna Aircraft Co Hydraulic pump or motor

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3999466A (en) * 1973-06-30 1976-12-28 Eckhard Aschke Hydrostatic pump/motor unit
US4631000A (en) * 1984-07-16 1986-12-23 Sundstrand Corporation Variable displacement hydraulic pressure intensifier
DE4396844C2 (de) * 1992-12-22 1998-05-07 Komatsu Mfg Co Ltd Vorrichtung zur Steuerung von Druck in den Zylinderkammern von hydraulischen Pumpen und Motoren
FR2725759A1 (fr) * 1994-10-17 1996-04-19 Caterpillar Inc Module hydraulique a pistons axiaux a course variable
US5554007A (en) * 1994-10-17 1996-09-10 Caterpillar Inc. Variable displacement axial piston hydraulic unit
US6361285B1 (en) 1998-12-22 2002-03-26 Parker Hannifin Gmbh Valve plate with hydraulic passageways for axial piston pumps
US6705203B2 (en) 2001-11-28 2004-03-16 Sauer-Danfoss Inc. Extended male slipper servo pad arrangement for positioning swashplate and method assembling same
EP2933485A1 (de) 2014-04-17 2015-10-21 Danfoss Power Solutions GmbH & Co. OHG Hydraulikpumpe mit verstellbarer fördermenge
US10012228B2 (en) 2014-04-17 2018-07-03 Danfoss Power Solutions Gmbh & Co. Ohg Variable fluid flow hydraulic pump
US11592000B2 (en) 2018-07-31 2023-02-28 Danfoss Power Solutions, Inc. Servoless motor

Also Published As

Publication number Publication date
GB1363990A (en) 1974-08-21
DE2217891A1 (de) 1972-10-19
FR2132869B1 (de) 1977-07-08
FR2132869A1 (de) 1972-11-24
JPS5520072B1 (de) 1980-05-30

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