US3924969A - Hydraulic system - Google Patents

Hydraulic system Download PDF

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Publication number
US3924969A
US3924969A US519101A US51910174A US3924969A US 3924969 A US3924969 A US 3924969A US 519101 A US519101 A US 519101A US 51910174 A US51910174 A US 51910174A US 3924969 A US3924969 A US 3924969A
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United States
Prior art keywords
pressure side
piston
fluid
pressure
machine
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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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US519101A
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English (en)
Inventor
Werner Rometsch
Karl Veil
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of US3924969A publication Critical patent/US3924969A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/18—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by varying the volume of the working chamber
    • F04C14/22—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by varying the volume of the working chamber by changing the eccentricity between cooperating members
    • F04C14/223—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by varying the volume of the working chamber by changing the eccentricity between cooperating members using a movable cam
    • 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

Definitions

  • a variable-flow hydraulic pump has an adjusting member movable between a plurality of flow-adjusting positions. A larger and a smaller piston act upon this member at opposite sides thereof. The smaller piston is always connected with the high-pressure side of the pump.
  • a multi-position servo-control unit is connected in circuit with the high pressure side and the low-pressure side and includes a relief valve connected with the larger piston and serving to control the flow of fluid from the high-pressure side to the same when the fluid pressure exceeds a preset limit.
  • a control valve is connected with the high pressure side and with the servo-control unit and serves to operate at a pressure slightly below the preset limit and at this time to move the servo-control unit to a position in which the unit connects the larger piston with the high-pressure side and interrupts the communication of the larger piston with a low-pressure space.
  • the present invention relates to a hydraulic system in general, and more particularly to a hydraulic system which controls the operation of a variable-flow fluidhandling machine.
  • variable-flow fluid-handling machines for example pumps
  • control arrangements which include a pressure relief valve whose purpose it is to provide for a low-loss pressure limitation of the pump or a hydrostatic drive supplied with fluid from the pump.
  • the basic consideration behind such an arrangement is to protect the pump, the drive and the seals against overload pressures.
  • variable-flow fluid-handling machine having a high-pressure side and a low-pressure side and an adjusting member which is movable between a plurality of flow-adjusting positions.
  • a larger and a smaller piston act upon the member in mutually opposite directions, and the smaller piston is connected in circuit with the high-pressure side.
  • a multi-position servo-control unit is connected in circuit with the machine and includes a relief valve in circuit with the larger piston end of the machine for controlling the flow of fluid from the high-pressure side when the fluid pressure exceeds a preset limit.
  • a control valve is connected with the high-pressure side and with the servocontrol unit and is operative at a pressure slightly below the preset limit for moving the control unit to a position in which the unit connects the larger piston with the high-pressure side and interrupts communication of the larger piston with a low-pressure space.
  • FIGURE is a diagrammatic illustration showing a system according to the present invention.
  • the drawing shows an exemplary system according to the present invention, using a fluid-handling machine 10 which will be seen to be capable as operating both as a fluid pump and as a fluid motor.
  • the machine 10 will be described with respect to its operation as a variable flow rate pump. It has a rotor 1 1 which is mounted for rotation in a diagrammatically illustrated cavity 14 of a housing (the latter is not specifically shown) and is formed with a plurality of radially extending slots in which slot pistons or vanes 12 can slide radially inwardly and radially outwardly.
  • vanes 12 engage a control member, in the illustrated embodiment a control ring 13 which can be shifted in the cavity 14 from its one extreme position, that is illustrated in the drawing, to a plurality of other positions, thereby varying the extent to which fluid can flow through the pump per unit of time.
  • a control member in the illustrated embodiment a control ring 13 which can be shifted in the cavity 14 from its one extreme position, that is illustrated in the drawing, to a plurality of other positions, thereby varying the extent to which fluid can flow through the pump per unit of time.
  • This therefore, is a machine of the type generally known as sliding-vane motors or pumps and its operation per se is well known.
  • the displacement of the member 13 thus controls the rate of fluid flow in the machine 10 between zero value and a maximum value; displacement is effected with the aid of two pistons 15 and 16 which are respectively slidably mounted in two cylinder bores 17 and 18 formed in the housing at sides of the cavity 14 which are diametrally opposite one another, so that they engage the member 13 at diametrally opposite sides.
  • the diameter of the piston 16 is approximately twice as great as the piston 15, so that the pistons act as differential pistons.
  • Two fluid passages 19 and 20 communicate with the cavity 14. For purposes of explanation it will be assumed that the rotor 11 turns in the direction indicated by the arrow that the passage 19 represents the high pressure side and the passage 20 the low pressure side of the machine 10.
  • the high pressure side 19 may communicate with a user such as a hydraulic motor that is preferably connected in a closed circuit with the machine 1 1, so that a hydrostatic drive having a closed circuit exists.
  • the low pressure side 20 may communicate with a low pressure space, such as a reservoir.
  • a fluid conduit 21 extends from the low pressure pressure side or passage 20 to the high pressure side 19 and has a switching valve 22 accommodated, composed of a valve body 24 which cooperates either with one or the other of two valve seats 23, 23, so that each valve seat together with the valve body 24 constitutes a oneway valve blocking flow in one or the other direction in the conduit 21.
  • a conduit 25 branches off the conduit 21 at a location which is midway between the two valve seats 23, 23' and leads to the bore 17 for the piston 15, and also to a four port three-position valve 26 which is movable between three positions I, II and III.
  • the conduit 25 continues beyond the valve 26 to a servo-control unit 27 which in principle is configurated as a three-port three-position valve 27' which can be moved at will by means of a lever, a magnet or the like, into one of its switching positions I, II or III.
  • a further fluid passage extends from the valve 27 via the valve 26 to the fluid reservoir 29, and another fluid passage 30 extends from the valve 27' to a fluid passage 31 which communicates with the bore 18 in which the piston 16 is slidable and also to a relief valve 32 which is constructed as a two-port two-position valve having switching positions I and II.
  • the conduit 31 extends beyond the valve 32 and communicates with the conduit 21.
  • valve member of the valve 32 is biased by a spring 33, and at the opposite side it is biased by fluid acting upon it from a fluid line 34 which communicates with the line 25.
  • Springs 35 and 36 act upon the opposite ends of the valve member of the valve 26 and maintain it normally in the center position II.
  • a conduit 37 which communicates with the fluid line 20 also communicates with that end face of the valve member of the valve 26 which is engaged by the spring 35.
  • a conduit 38, branching off the fluid line 19, communicates with the opposite end face of the valve member in the valve 26, namely the end face which is engaged by the spring 36.
  • the valve member in the valve 27' of the servo-control unit 27 is also engaged at its opposite ends by springs 39 and 40, respectively.
  • valve 27' of the servo-control unit 27 When the pump is to operate and supply fluid into the high pressure fluid line 19 and from there to the user, the valve 27' of the servo-control unit 27 must be in the position III thereof.
  • the member 13 is mechanically shifted slightly in upward direction out of its zero position, counter to the action of the piston 16.
  • the pump is now capable of forcing pressure fluid into the fluid line 19 and the pressure which develops therein is communicated via the line 21 and the valve 23', 24 which opens under this pressure into the conduit 25.
  • the valve member 24 at this time is in sealing engagement with the valve seat 23.
  • the pressure existing in the fluid line 19 also is communicated via the conduit 38 to the valve 26 which is in the position 11, so that pressure fluid can travel via the fluid line 25 to the valve 27
  • the pressure in the bore 17 is the unthrottled pump pressure so that, as the pressure rises, the piston is moved upwardly counter to the force exerted by the piston 16, despite the fact that its surface area is smaller than that of the piston 16; this results in a displacement of the member 13 in a sense permitting an increased flow of fluid through the pump per unit time, until finally the maximum pumping position is reached which is shown in the drawing.
  • the valve 32 When the pump pressure reaches a predetermined maximum upper limit, the valve 32 is moved to its position I by the pressure which obtains in the conduit 34 which is in communication with the conduit 35; this movement takes place counter to the biasing force of the spring 33 and permits the unthrottled flow of pressure fluid via the conduit 2 1 and 31 into the bore 18. At this time, identical pressure is operative in the bores 17 and 18 upon the pistons 15 and 16, respectively. However, since the surface area of the piston 16 is greater than that of the piston 15, the piston 16 is able to overcome the force exerted by the piston 15 and the mem- 4 ber 13 is shifted (downwardly in the drawing) to towards its center position.
  • the valve 26 Shortly before the pressure is reached which is capable of switching the valve 32, the valve 26 is shifted by the fluid pressure acting in the line 38 out of its position II and into its position III in which it blocks the flow of pressure fluid from the bore 18 via the line 28 to the reservoir 29.
  • the servo-control unit 27 can now, when the valve 27' thereof is in a position located midway between the positions I and II, permit high pressure fluid from the line 28 to enter into the bore 18 and to continue to act upon the piston 16 in a sense shifting the member 13 to a position in which the flow through rate through the pump is reduced, and the pressure fluid is consequently also reduced.
  • the machine 10 If the machine 10 is connected in a closed circuit with a hydraulic motor and the latter itself operates as a pump, then the machine 10 will self-evidently be operating as a motor. In such a case, the machine 10 receives high pressure fluid from the user via the fluid line 20. In other words, in this type of operation the high and low pressure sides will be reversed and the fluid line 19 will now be the low pressure side. If in such operation the maximum pressure value is reached at the valve 32 moves to its position I, then the bore 18 is connected with the now low pressure line 19 via the line 31 and the valve 32 as well as the line 21.
  • the pump 10 or motor 10 depending upon the manner in which it is operated, can also be so constructed that it can be reversible, that is that it can be adjustable +Q via zero to -Q a1.
  • the arrangement according to the present invention will be fully effective.
  • a hydraulic system comprising a variable-flow fluid-handling machine having a high-pressure side and a low-pressure side and an adjusting member which is movable between a plurality of flow-adjusting positions; a larger and a smaller piston acting upon said member in mutually opposite directions, said smaller piston being connected in circuit with said high-pressure side; a multi-position servo-control unit to which said larger piston is mechanically connected so as to share the movements thereof, said unit connected in circuit with said machine and including a relief valve in circuit with said larger piston and said machine for controlling the flow of fluid from said high-pressure side when the fluid pressure exceeds a preset limit; and a control valve connected with said high-pressure side and said unit and operative at a pressure slightly below said preset limit for moving said unit to a position in which said unit connects said larger piston with said high-pressure side and interrupts communication of said larger piston with a low-pressure space.
  • a hydraulic system comprising a variable-flow fluid-handling machine which is operable at will as a pump or as a hydraulic motor, said machine having a high-pressure side and a low-pressure side and an adjusting member which is movable between a plurality of flow-adjusting positions; a larger and a smaller piston acting upon said member in mutually opposite directions, said smaller piston being connected in circuit with said high-pressure side; a multi-position servocontrol unit to which said larger piston is mechanically connected so as to share the movements thereof, said unit connected in circuit with said machine and including a relief valve in circuit with said larger piston and said machine for controlling the flow of fluid from said high-pressure side when the fluid pressure exceeds a preset limit; and a four-port three-position slide control valve being operable in both modes of operation of said machine and being connected with said high-pressure side and said unit and operative at a pressure slightly below said preset limit for moving said unit to a position in which said unit connects said larger piston with said high-pressure side and interrupts communication of said larger

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Details And Applications Of Rotary Liquid Pumps (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Fluid-Pressure Circuits (AREA)
US519101A 1973-11-14 1974-10-30 Hydraulic system Expired - Lifetime US3924969A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2356795A DE2356795A1 (de) 1973-11-14 1973-11-14 Steuereinrichtung fuer eine verstellbare pumpe

Publications (1)

Publication Number Publication Date
US3924969A true US3924969A (en) 1975-12-09

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ID=5898068

Family Applications (1)

Application Number Title Priority Date Filing Date
US519101A Expired - Lifetime US3924969A (en) 1973-11-14 1974-10-30 Hydraulic system

Country Status (5)

Country Link
US (1) US3924969A (https=)
JP (1) JPS5080502A (https=)
DE (1) DE2356795A1 (https=)
FR (1) FR2250905B3 (https=)
GB (1) GB1467706A (https=)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4072442A (en) * 1975-07-04 1978-02-07 Takeshi Horiuchi Variable delivery hydraulic pump
US4509902A (en) * 1982-04-10 1985-04-09 Robert Bosch Gmbh Power regulating device for a hydrostatic pump
US20080063537A1 (en) * 2004-09-20 2008-03-13 Matthew Williamson Speed-Related Control Mechanism For A Pump And Control Method
CN102797674A (zh) * 2011-05-23 2012-11-28 日立汽车系统株式会社 容量可变型泵
US20170234311A1 (en) * 2012-09-07 2017-08-17 Hitachi Automotive Systems, Ltd. Variable displacement pump
US10161398B2 (en) 2014-12-01 2018-12-25 Hitachi Automotive Systems, Ltd. Variable displacement oil pump
WO2022135742A1 (en) 2020-12-24 2022-06-30 Robert Bosch Gmbh Hydraulically actuated continuously variable transmission for an electric vehicle

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2825827C2 (de) * 1978-06-13 1982-06-16 Danfoss A/S, 6430 Nordborg Stellmotor mit Nachlaufsteuerung für hydraulische Verstellmaschinen
DE102007033194A1 (de) * 2007-07-17 2009-01-22 Zf Lenksysteme Gmbh Verdrängerpumpe mit variablem Fördervolumen
DE102012217100A1 (de) * 2012-09-24 2014-04-17 Robert Bosch Gmbh Pumpenanordnung umfassend eine Flügelzellenpumpe

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2179071A (en) * 1938-04-09 1939-11-07 Oilgear Co Control for hydrodynamic machines
US2368791A (en) * 1941-10-06 1945-02-06 Hydraulic Dev Corp Inc Servomotor
US3067693A (en) * 1958-12-24 1962-12-11 United Aircraft Corp Control means for variable delivery pump
US3644063A (en) * 1969-04-05 1972-02-22 Bosch Gmbh Robert Regulated hydraulic apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2179071A (en) * 1938-04-09 1939-11-07 Oilgear Co Control for hydrodynamic machines
US2368791A (en) * 1941-10-06 1945-02-06 Hydraulic Dev Corp Inc Servomotor
US3067693A (en) * 1958-12-24 1962-12-11 United Aircraft Corp Control means for variable delivery pump
US3644063A (en) * 1969-04-05 1972-02-22 Bosch Gmbh Robert Regulated hydraulic apparatus

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4072442A (en) * 1975-07-04 1978-02-07 Takeshi Horiuchi Variable delivery hydraulic pump
USRE31711E (en) * 1975-07-04 1984-10-23 Daikin Kogyo Co., Ltd. Variable delivery hydraulic pump
US4509902A (en) * 1982-04-10 1985-04-09 Robert Bosch Gmbh Power regulating device for a hydrostatic pump
US20080063537A1 (en) * 2004-09-20 2008-03-13 Matthew Williamson Speed-Related Control Mechanism For A Pump And Control Method
US8123492B2 (en) * 2004-09-20 2012-02-28 Magna Powertrain Inc. Speed-related control mechanism for a pump and control method
CN102797674A (zh) * 2011-05-23 2012-11-28 日立汽车系统株式会社 容量可变型泵
US20120301342A1 (en) * 2011-05-23 2012-11-29 Hitachi Automotive Systems, Ltd. Variable Displacement Pump
US9004882B2 (en) * 2011-05-23 2015-04-14 Hitachi Automotive Systems, Ltd. Variable displacement vane pump having multiple dampening springs
US20170234311A1 (en) * 2012-09-07 2017-08-17 Hitachi Automotive Systems, Ltd. Variable displacement pump
US10006457B2 (en) * 2012-09-07 2018-06-26 Hitachi Automotive Systems, Ltd. Variable displacement pump
US10161398B2 (en) 2014-12-01 2018-12-25 Hitachi Automotive Systems, Ltd. Variable displacement oil pump
WO2022135742A1 (en) 2020-12-24 2022-06-30 Robert Bosch Gmbh Hydraulically actuated continuously variable transmission for an electric vehicle
NL1043880B1 (en) 2020-12-24 2022-07-20 Bosch Gmbh Robert Hydraulically actuated continuously variable transmission for an electric vehicle

Also Published As

Publication number Publication date
DE2356795A1 (de) 1975-05-15
FR2250905A1 (https=) 1975-06-06
FR2250905B3 (https=) 1977-08-12
JPS5080502A (https=) 1975-06-30
GB1467706A (en) 1977-03-23

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