US3554671A - Device for adjusting the stroke of a variable displacement pump to maintain the product of pressure and volume per stroke constant - Google Patents

Device for adjusting the stroke of a variable displacement pump to maintain the product of pressure and volume per stroke constant Download PDF

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Publication number
US3554671A
US3554671A US754006A US3554671DA US3554671A US 3554671 A US3554671 A US 3554671A US 754006 A US754006 A US 754006A US 3554671D A US3554671D A US 3554671DA US 3554671 A US3554671 A US 3554671A
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US
United States
Prior art keywords
adjusting
pivot
stroke
pressure
moment
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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
Application number
US754006A
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English (en)
Inventor
Gunter Schlinke
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.)
BELLOWS VALVAIR KAMPER GmbH
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BELLOWS VALVAIR KAMPER GmbH
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Publication of US3554671A publication Critical patent/US3554671A/en
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Expired - Lifetime legal-status Critical Current

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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
    • 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
    • F04B49/08—Regulating by delivery pressure
    • 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
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/46—Automatic regulation in accordance with output requirements
    • F16H61/475—Automatic regulation in accordance with output requirements for achieving a target power, e.g. input power or output power

Definitions

  • a device for adjusting the stroke of a variable displacement pump to keep the product of the pressure and volume per stroke constant comprises a fluid pressure actuated adjusting member for varying the volume per stroke of the pump, the flow of fluid to the adjusting member being controlled by a spool valve, an auxiliary member mounted on a pivot, the pivot being carried by and movable with the adjusting member, the auxiliary member being urged to turn about the pivot in one direction by equalising means subjecting said member to a predetermined substantially constant moment, the spool of the spool valve being adapted to transmit a force to the auxiliarly member proportional to the pump output pressure, the moment of said force opposing the moment of the equalising member, the moment of the force varying with the movement of the pivot in proportion to the volume per stroke.
  • This invention relates to a device for adjusting the stroke of variable displacement pumps to maintain the product of the pump output pressure and the volume per stroke at a preset constant value, the displacement pumps having a pressure actuated adjusting member for varying the volume per stroke.
  • Devices of the above-mentioned kind are known wherein the adjusting member is acted upon by a set of springs which, above a certain fluid-pressure determining the commencement of the control range, are loaded or relieved of load'to varying degrees by the adjusting member in such manner that the stroke of the adjusting member increases in accordance with a prescribed ratio as the pump pressure rises, and the volume per stroke drops, so that the product of the pump output pressure and the volume per stroke remains constant.
  • the springs are here so selected that their characteristic curve is practically hyperbolic when the relationship between the change in volume per stroke and the distance travelled by the adjusting member is linear or almost linear.
  • the object of the present invention is to eliminate the disadvantages described and to provide an improved device of the kind in question such that, on that one hand, an exact hyperbolic relationship between the pump output pressure and the volume per stroke is ensured and, on the other hand, it is possible readily to vary the characteristic capacity curve.
  • the invention consists in a device for adjusting the stroke of a variable displacement pump to maintain the product of pump output pressure and volume per stroke at a preset constant value, comprising fluid-pressure-actuated stroke adjusting means displaceable for varying the volume per stroke of the pump, valve means for controlling the application of fluid pressure to said stroke adjusting means, a pivot carried by said stroke adjusting means for displacement therewith, a member mounted for rotational movement about said pivot and adapted to operate said valve means in accordance with said rotational movement, equalising means subjecting said member to a preset substantially constant moment above said pivot tending to rotate said member in one direction, and said valve means being adapted to transmit to said member a force proportional to pump output pressure the moment of said force about said pivot tending to rotate said member in the opposite direction and the length of the moment arm being varied by displacement of said pivot in proportion to the volume per stroke.
  • the device according to the invention offers the advantage that in each unchanging condition the moment of rotation applied by the valve means to the auxiliary member is constant, that is, equal to a value a.f.p, where ;f is the area of the valve spool subjected to the operating pressure 2 and a is the distance from the pivot member to the point of engagement of the valve spool With the auxiliary member. Since, however, a is proportional to the position of the adjusting member and consequently to the volume per stroke V not only does the product a.f.p remain constant, but it can be said that f.p.V is constant, and the requirement regarding an exact regulation of capacity is met.
  • the auxiliary member takes the form of a double-armed lever, one arm of which, cooperating with the spool, is provided with a guide for the pivot member which is attached to the adjusting member, its other arm, cooperating with the equalising member, forming a pivoting arm of substantially constant length b.
  • the disposition of the auxiliary member relatively to the valve spool and the equalising member is here preferably so selected that the valve spool acts on the arm incorporating the guide transversely of this guide and the equalising member acts on the other arm in a direction parallel with the path of movement of the pivot member.
  • the magnitude of the forces applied by the equalising member is adjustable. This can be achieved for example by the equalising member including a spring, the force of which is adjustable.
  • the equalising member includes a control piston actuable by a fluid medium of variable pressure.
  • FIG. 1 shows schematically and in section the side view of a device according to the invention fitted to a reciprocating piston pump
  • FIG. 2 shows part of a modified form of the device shown in FIG. 1, and
  • FIG. 3 shows part of a further modified form of the device shown in FIG. 1.
  • the volume per stroke per revolution of the pump depends upon the stroke H of each individual piston a part 11 of each piston engaging swash-plate 12 about an axis 13.
  • an adjusting member 14 which is connected to the swash plate 12 by way of a rod 16 mounted in a ball-joint 15.
  • the adjusting member 14 incorporates a piston part 19, displaceable in two directions within a cylinder 20 by fluid pressure which enters cylinder 20 by way of connection orifices 17 and 18.
  • a spring 21 presses the adjusting member 14 into the end position illustrated when the pump output pressure p is zero. At this position the volume V per stroke is at its greatest.
  • the annular space 22 in the cylinder 20 communicates by way of a pipe 23 with a pipe 24 in which the pump output pressure 1 obtains and which is also connected with the orifice 25 of the cylinder 26 of a spool valve 27.
  • the valve 27 includes a spool 28 the cross-sectional area of which has the value 1.
  • the spool 28 opens and closes a passage 29, which communicates with the connection orifice 18 by way of a pipe 30, the connection orifice 18 in turn communicating with the cylinder chamber 61 beneath piston 19.
  • a further orifice 31 in the cylinder 26 connects the annular space 32 in the cylinder, via a pipe 33, with the atmosphere or with a sump 34 for the pressure medium employed.
  • the pivot member 39 is guided in a slot 40; its perpendicular distance a from the centre line of the valve 27 depends upon the position of the adjusting member 14, since it is firmly connected thereto by way of an adjusting spindle 41 and a slotted bolt 42.
  • the spring force P is applied to the lever arm 37 at a substantially constant perpendicular distance from the pivot member 39 during the swinging movements of the auxiliary member 36 about member 39.
  • the device according to the invention operates as follows:
  • a pump output pressure p builds up in the pipe 24.
  • a pressure medium flows through the orifice 25 into the cylinder 26 and applies a force pj where f is the working area of the spool 28 of the valve 27
  • the force 12. initiates a moment of rotation of the magnitude a.p.f in the auxiliary member 36, which moment balances the moment of rotation P Xb, where P is the force exerted by the equalising member on the lever arm 37 of the auxiliary member 36.
  • This swinging movement brings about a displacement of the spool 28 to the left, whereby the passage 29 is uncovered and pressure medium flows into the cylinder chamber 61.
  • the increasing pressure in the cylinder chamber 61 causes an upward movement of the adjusting member 14 and thus a shortening of the swinging arm a to a value 11
  • the upward movement of the adjusting member continues until the moment of rotation from the force p f acting on the auxiliary member 36 and the value a attains a value which again corresponds to the moment of rotation P b.
  • the auxiliary member 36 begins to move back again in the clockwise direction, and the spool 28 returns to its initial position. A new condition of equilibrium is then established.
  • the regulating device only begins to respond when the moment of rotation a.p.f assumes a value greater than the moment of rotation P Xb. By altering the amount of P the commencement of regulation can consequently be altered together with the characteristic curve of the pump.
  • the double-armed lever constituting the auxiliary member 36 is so shaped that the force P is applied at a point which lies on a line which is perpendicular to the direction of movement of pivot member 39 and passes substantially through the middle of its path of movement. In this way, the lever arm b is kept substantially constant.
  • the equalising member providing a counter-force to the force applied by the spool 28 to the auxiliary member 36, operates with a spring
  • the counter-force in the construction shown in FIG. 2 takes the form of a counter-weight consisting of several discs 49.
  • This counter-weight is suspended on a cord 51 which passes round a roller and engages in a notch 54 in the auxiliary member 55 by means of a tensioning yoke 52 having a knife-edge 53.
  • the auxiliary member is coupled with a spool 58 via a ball-joint 56, 57.
  • FIG. 3 shows a further variant of the device shown in FIG. 1, wherein the counter-force is provided by means of a piston 59 which is actuable by a fluid medium and is guided in a cylinder 60.
  • the last-described form of construction otters the advantage that it enables the counter-force to be adjusted by remote control.
  • a device for adjusting the stroke of a variable displacement pump to maintain the product of pump output pressure and volume per stroke at a preset constant value comprising fluid-pressure actuated stroke adjusting means displaceable for varying the volume per stroke of the pump, valve means for controlling the application of fluid pressure to said stroke adjusting means, a pivot carried by said stroke adjusting means for displacement therewith, a double-armed lever mounted for rotational movement about said pivot and adapted to operate said valve means in accordance with said rotational movement, one of the arms of said lever cooperating with said valve means and provided with guide means for said pivot, said valve means acting on said last mentioned arm transversely thereof, equalising means subjecting said lever to a preset substantially constant movement above said pivot tending to rotate said lever in one direction, and the other arm of said lever cooperating with said equalising means to form a moment arm of substantially constant length whereby said valve means transmits to said lever a force proportional to pump output pressure with the moment of said force about said pivot tending to rotate said lever ill a direction parallel to the path of movement
  • valve means includes a spool the longitudinal axis of the spool extending through the pivot attached to the member in the neutral position of the adjusting member.
  • a device for maintaing the product of the amount of fluid delivered by a pump and the pump output pressure at a preset constant value comprising fluid-pressureactuated adjusting means displaceable for varying the delivered amount of fluid, valve means mounted in a stationary housing and serving to control the application of fluid pressure to said adjusting means, a pivot carried by said adjusting means for displacement therewith, a member mounted for rotational movement about said movable pivot and adapted to operate said valve means in accordance with that rotational movement, first operating means adapted to transmit to said member a force proportional to pump output pressure with said force being dependent upon the movement of said pivot and said adjusting means, the moment of said force about said pivot tending to rotate said member in one direction, second operating means subjecting said member to a preset substantially constant moment tending to rotate said member in the opposite direction.
  • valve means includes a spool forming the first operating means, the longitudinal axis of the spool extending through the pivot attached to the member in the neutral position of the adjusting member.
  • the adjusting member includes at least two parts adjustably connected together for adjusting the position of the pivot member relative to the spool.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Control Of Fluid Gearings (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Hydraulic Motors (AREA)
US754006A 1967-08-25 1968-08-20 Device for adjusting the stroke of a variable displacement pump to maintain the product of pressure and volume per stroke constant Expired - Lifetime US3554671A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1653385A DE1653385C3 (de) 1967-08-25 1967-08-25 Vorrichtung zum Konstanthalten des Produktes aus Druck und Hubvolumen bei einer Verdrängerpumpe

Publications (1)

Publication Number Publication Date
US3554671A true US3554671A (en) 1971-01-12

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ID=6987426

Family Applications (1)

Application Number Title Priority Date Filing Date
US754006A Expired - Lifetime US3554671A (en) 1967-08-25 1968-08-20 Device for adjusting the stroke of a variable displacement pump to maintain the product of pressure and volume per stroke constant

Country Status (7)

Country Link
US (1) US3554671A (de)
JP (1) JPS4937927B1 (de)
AT (1) AT276955B (de)
CH (1) CH485122A (de)
DE (1) DE1653385C3 (de)
FR (1) FR1565961A (de)
GB (1) GB1234416A (de)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3694108A (en) * 1969-04-23 1972-09-26 Carlo Pensa Hydraulic apparatus for regulating the flow of one or more pumps
US3861832A (en) * 1972-08-04 1975-01-21 Poclain Sa Pump power governor
US3958496A (en) * 1973-04-25 1976-05-25 Volvo Flygmotor Aktiebolag Control device for hydraulic machines
US4028018A (en) * 1974-06-10 1977-06-07 Paterson Candy International Limited Non-pulsing apparatus
USRE29333E (en) * 1969-04-23 1977-08-02 Massey-Ferguson Services N.V. Hydraulic apparatus for regulating the flow of one or more pumps
US4273517A (en) * 1977-08-03 1981-06-16 Linde Aktiengesellschaft Control device for an axial piston machine
US4639195A (en) * 1984-01-19 1987-01-27 Linde Aktiengesellschaft Power control devices for hydrostatic pumps
US5241872A (en) * 1991-05-20 1993-09-07 Sauer Inc. Swashplate centering mechanism for a variable displacement pump
US20100269687A1 (en) * 2007-10-09 2010-10-28 Danfoss A/S Hydraulic axial piston machine
CN110792568A (zh) * 2018-07-25 2020-02-14 丹佛斯动力***有限责任两合公司 转矩控制和反馈装置
US11293417B2 (en) * 2017-06-22 2022-04-05 Komatsu Ltd. Hydraulic pump and motor
US11598322B2 (en) * 2020-02-13 2023-03-07 Robert Bosch Gmbh Hydrostatic axial piston machine of swash plate construction

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2146586C3 (de) * 1971-09-17 1981-12-17 G.L. Rexroth Gmbh, 8770 Lohr Mit einer Konstantzug-Regelung versehener hydrostatischer Antrieb
JPS5141818U (de) * 1974-09-20 1976-03-27
JPS5264429U (de) * 1975-11-06 1977-05-12
JPS5320736U (de) * 1976-07-31 1978-02-22
DE2737963C3 (de) * 1977-04-26 1981-03-19 Kurt Wilen-Wollerau Christiansen Volumenregler für Hydroeinheit
DE2930139A1 (de) * 1979-07-25 1981-02-12 Linde Ag Regeleinrichtung fuer ein hydrostatisches getriebe oder eine kolbenpumpe
DE2930106A1 (de) * 1979-07-25 1981-02-12 Linde Ag Regeleinrichtung fuer eine hydrokolbenpumpe
DE2938088A1 (de) * 1979-09-20 1981-04-02 Linde Ag, 6200 Wiesbaden Regeleinrichtung fuer eine einstellbare hydrokolbenpumpe
US4508011A (en) * 1982-04-02 1985-04-02 Abex Corporation Hydraulic axial piston machine
DE3408105A1 (de) * 1984-03-05 1985-09-12 Hydromatik GmbH, 7915 Elchingen Summenleistungs-regelvorrichtung fuer eine wenigstens zwei pumpen oder pumpengruppen mit veraenderlichem foerdervolumen und mit einem gemeinsamen antrieb aufweisende hydrostatische anlage

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3694108A (en) * 1969-04-23 1972-09-26 Carlo Pensa Hydraulic apparatus for regulating the flow of one or more pumps
USRE29333E (en) * 1969-04-23 1977-08-02 Massey-Ferguson Services N.V. Hydraulic apparatus for regulating the flow of one or more pumps
US3861832A (en) * 1972-08-04 1975-01-21 Poclain Sa Pump power governor
US3958496A (en) * 1973-04-25 1976-05-25 Volvo Flygmotor Aktiebolag Control device for hydraulic machines
US4028018A (en) * 1974-06-10 1977-06-07 Paterson Candy International Limited Non-pulsing apparatus
US4273517A (en) * 1977-08-03 1981-06-16 Linde Aktiengesellschaft Control device for an axial piston machine
US4639195A (en) * 1984-01-19 1987-01-27 Linde Aktiengesellschaft Power control devices for hydrostatic pumps
US5241872A (en) * 1991-05-20 1993-09-07 Sauer Inc. Swashplate centering mechanism for a variable displacement pump
US20100269687A1 (en) * 2007-10-09 2010-10-28 Danfoss A/S Hydraulic axial piston machine
US9051926B2 (en) * 2007-10-09 2015-06-09 Danfoss A/S Hydraulic axial piston machine
US11293417B2 (en) * 2017-06-22 2022-04-05 Komatsu Ltd. Hydraulic pump and motor
CN110792568A (zh) * 2018-07-25 2020-02-14 丹佛斯动力***有限责任两合公司 转矩控制和反馈装置
US11598322B2 (en) * 2020-02-13 2023-03-07 Robert Bosch Gmbh Hydrostatic axial piston machine of swash plate construction

Also Published As

Publication number Publication date
FR1565961A (de) 1969-05-02
DE1653385A1 (de) 1970-08-27
JPS4937927B1 (de) 1974-10-14
CH485122A (de) 1970-01-31
AT276955B (de) 1969-12-10
DE1653385C3 (de) 1980-07-24
GB1234416A (de) 1971-06-03
DE1653385B2 (de) 1979-09-27

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