EP0081941A2 - Hydraulisches Ventil - Google Patents

Hydraulisches Ventil Download PDF

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Publication number
EP0081941A2
EP0081941A2 EP82306373A EP82306373A EP0081941A2 EP 0081941 A2 EP0081941 A2 EP 0081941A2 EP 82306373 A EP82306373 A EP 82306373A EP 82306373 A EP82306373 A EP 82306373A EP 0081941 A2 EP0081941 A2 EP 0081941A2
Authority
EP
European Patent Office
Prior art keywords
valve
spool
fluid
hydraulic
pressure
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.)
Withdrawn
Application number
EP82306373A
Other languages
English (en)
French (fr)
Other versions
EP0081941A3 (de
Inventor
Ganesh Rajagopal
Richard Tallian
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.)
Ford Werke GmbH
Ford France SA
Ford Motor Co Ltd
Ford Motor Co
Original Assignee
Ford Werke GmbH
Ford France SA
Ford Motor Co Ltd
Ford Motor Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ford Werke GmbH, Ford France SA, Ford Motor Co Ltd, Ford Motor Co filed Critical Ford Werke GmbH
Publication of EP0081941A2 publication Critical patent/EP0081941A2/de
Publication of EP0081941A3 publication Critical patent/EP0081941A3/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor

Definitions

  • This invention relates to a hydraulic valve.
  • a hydraulic valve for controlling the flow of hydraulic fluid from a source of fluid under pressure to and from at least one load shifting hydraulic motor, the valve comprising a valve body housing an axially movable main spool for directing fluid through selective ones of a plurality of passages extending through the valve body from a fluid input connection to the fluid source to one or more fluid output connections, characterised by spool manipulator means actuable to shift said valve main spool in either axial direction from a neutral position to cause actuation of the hydraulic motor to move a load coupled thereto in a desired direction, and a load position holding system having pilot operated poppet valves operative to minimise fluid leakage past the main spool when the latter is in a neutral position.
  • the hydraulic valve described herein is used to control the flow of hydraulic fluid (which could be at high pressure) to and from hydraulic motors connected to the valve.
  • Two embodiments of the valve are shown. The first embodiment is mechanically actuated and the second embodiment is electrically controlled. A majority of the parts are common to both valves. The primary application of these valves is in agricultural tractors.
  • Figure 1 shows the mechanical version of the valve 10 with the main spool 11 in the neutral position.
  • the inlet port 12 and the pilot signal port 13 of the valve 10 can be connected either to the output port 14 and signal port 15 of an unloading valve 16 when the hydraulic supply is from a fixed displacement pump 17, or to the output port 18 and signal port 19 of a pressure flow compensated, variable displacement pump 21. It is possible to connect several valves similar to valve 10 simultaneously to the outlet ports 14 or 18 and the signal ports 15 or 19 of the two hydraulic sources.
  • valve 22 is shown connected to ports 14 and 15.
  • the output ports 23 and 24 of the valve are shown connected to any other hydraulic motor or actuator with two ports.
  • the chambers 27 and 28 of the valve 10 are internally connected together, and by means of a return port, to the sump of the hydraulic system. (not shown).-In Figure 1, the outlet ports 23 and 24 are formed by the quick- disconnect couplers 29 and 31 which are housed in the same body as valve 10. The couplers 29 and 31 act as through passageways between port 23 and passage 32 and between port 24 and passage 33, respectively, once they are connected to the coupling hoses from the hydraulic motor.
  • the load check valves 34 and 35 are seated and prevent the load (in this case a weight on cylinder 25) from moving.
  • the oil in passage 32 is also connected . through orifice 36 and passage 37 to chamber 38.
  • the oil in chamber 38 is checked by ball 39 which seals orifice 41.
  • Sleeve 42 in the neutral position, allows pilot actuating pin 43 to exert no force on ball 39 so that the oil in chamber 38 is prevented from entering orifice 41 and from there draining to the chamber 28.
  • the oil in. passage 33 is connected through orifice 44 and. passage 45 to chamber 46. With the sleeve 42 in the neutral position, pin 47 exerts no force on ball 48, and the oil in chamber 46 is prevented from entering orifice 49 and thence draining into chamber 28.
  • Sleeve 42 is a separate part which is attached to the spool 11 by means of shims and a snap ring so that the relative motion of the pins 43 and 47 with respect to the opening and closing of the pressure and tank ports is in the right sequence. It is possible to make the sleeve a part of the spool itself in designs where a larger deadband at neutral is permissible, or where other dimensions related to the opening and closing of ports are held to suitable tolerances.
  • An advantage of the present design, where the sleeve 42 is a separate part from the spool, is that the side loads on the sleeve, exerted by the pins 43 and 47 and the detent plunger 51, are not transmitted to the spool but are directly transmitted to the body of the valve 10. This lessens the chances of binding for the main spool 11 since it is subjected only to axial loads.
  • spool 11 In the absence of external forces, spool 11 is held at the neutral position by the spring arrangement in the housing 52.
  • the edges 53 and 54 on the spool 11 are positioned so as to close off the chamber 55 which is connected through passage 56, the slot in the flow control valve 57 and holes in pressure compensating spool 58 to passage 59 and the inlet port 12 to which the pressure supply is connected.
  • Edges 61 and 62 on the spool 11 have a small taper on their diameter so that at the neutral position chamber 63 drains into chamber 27 and chamber 64 drains into chamber 28.
  • Chambers 63 and 64 j are connected to the shuttle valve 65 which allows only the larger pressure of the two to be sensed at chamber 66 and through t orifice 67 at chamber 68.
  • the sleeve 42 When spool 11 moves to the left, the sleeve 42 also moves with it. After a certain small initial displacement, sleeve 42 contacts pin 43 and starts raising it. When the pin 43 rises, it contacts ball 39 and raises it off its seat on orifice 41. Once the ball 39 is off its seat, oil in the chamber 38, passageway 37 and chamber 71 can drain to the chamber 28 through orifice 36., This causes a pressure difference on either side of the poppet check valve 34 so that it is unseated and opens communication between channel 32 and chamber 63.
  • edge 54 opens a,flow path between the chamber 55 and chamber 64.
  • edge 62 of the spool 11 closes off the flow path between chamber 64 and chamber 28.
  • Edge 61 on the spool 11 opens up the flow path between chamber 63 and chamber 27. Oil flowing into chamber 64 will not be able to flow into passage 33 until the pressure in chamber 64 is greater than the pressure in passage 33. The pressure in chamber 64 builds up to the required level as follows.
  • the pressure in chamber 64 is transmitted through the shuttle valve 65, chamber 66, check valve 69, and load sensing port 13 to the port 15 on the unloading valve 16. This causes the pressure at port 14 to rise to the level of the pressure in port 15 plus the standby pressure level of the unloading valve.
  • the pressure in port 15 is fed back into the valve 10 through port 12, passages 59, 56, 55 and into 64. Thus, the pressure in chamber 64 continues to rise until the check valve 35 is opened and flow can proceed to the cylinder 24.
  • the return flow from the cylinder enters the valve 10 at port 23 and is drained in chamber 16 through passage 32 and chamber 63.
  • the pressure compensating spool 58 provides a means by which the flow of oil from chamber 55 into chamber 64 is made proportional to the area opened up by edge 54 of the spool.
  • the flow control valve 57 is assumed to be wide open so that the area of flow at the flow control valve is much larger than the flow area exposed by edge 54 of the spool.
  • the flow area exposed by edge 54 may be made to follow any suitable function of the axial displacement of the spool 11. For example, the area may be directly proportional to the displacement.
  • the pressure compensating spool 58 seeks to do this.
  • the pressure drop P is the difference in pressure between the pressures in chambers 55 and 64.
  • the pressure in chamber 55 is sensed at the left end of the spool 58 and the pressure in chamber 64 is sensed at the right end of the spool in the cavity 68.
  • the spool is also subjected to a force by spring 71 which opposes and balances the force on the spool due to the pressure difference, P, across it. If the force due to the pressure difference exceeds the spring force, spool 58 chokes the incoming flow at the metering edge 73 so that the force balance is restored.
  • the spool 58 attempts to restore the balance by reducing the restriction at edge 73. In this manner, the flow across the edge 54 of the main spool 11 is held almost constant for a given position of the spool, irrespective of fluctuations in supply or load pressures.
  • One advantage of holding the pressure drop constant across the metering area of the main spool 11 is that the flow forces on the spool are also constant and usually lower than in designs where the maximum possible pressure drop is allowed to occur across the spool. Reduced flow forces mean that the effort needed to move the spool is reduced, which is an advantage during manual operation of the valve.
  • the output flow increases proportionally to the area opened up by edge 54.
  • sleeve 42 causes detent piston 51 to raise. This is sensed by a human operator as an increase in resistance to the further movement of the spool. This feature is provided so that the operator has a means of sensing when the spool will be going into detent. If the operator wishes to put the spool into detent, he can force the spool a little further and the detent piston 51 will continue to hold the sleeve 42 and the spool 11 in that position. If the operator does not wish to detent the spool, he has an indication- that he has reached the maximum flow position of the spool. This feature is desired when the valve is stroked continually as in loader operation.
  • the spool 11 may be taken out of detent and returned to neutral either manually by overcoming the resistance of the detent piston 51 or automatically when the system pressure reaches a preset value.
  • the pressure in chamber 55 exceeds the pressure, set at relief valve 74, oil flows into chamber 75 and pushes the detent piston back so that the sleeve 42 (and spool 11) may return to the neutral position.
  • This feature is required when the spool is placed in detent and the cylinder 25 strokes until it reaches the end of its travel.
  • the pressure then builds up to the pump relief pressure, unless it is relieved by returning the spool 11 to neutral.
  • the pressure in chamber 55 drops to the standby level, the relief valve 74 reseats, and the detent piston 51 is returned by its spring.
  • the function of the flow control valve 57 is to restrict the maximum flow from the valve to a prese t value when the spool 11 is put into its first detent position when moving to the left. This is done by varying flow area 76 by rotating the valve 57 through control lever 78. Since the flow through the valve is proportional to the flow area across which the pressure drop is maintained by the pressure compensating spool 58, varying area 76 effectively controls the flow through the valve when the spool 11 is set at its detent position.
  • Edge 53 of the spool moves to the right, allowing flow from the inlet chamber 55 to enter chamber 63.
  • the pressure in chamber 63 is fed back to the pump through shuttle valve 65 and sensing port 13 so that the pressure starts building up until it is able to overcome pressure in passage 32 and open the poppet check valve 34.
  • the flow can then proceed to the outlet port 23 and the rod end of the cylinder 25.
  • sleeve 42 moves to the right with spool 11, it causes pin 47 to move so as to raise ball 48 off its seat. This allows oil in chamber 79 ; , passage 45 and chamber 46 to drain past orifice 49 into the chamber 28.
  • Flow control is obtained by varying the flow area between chambers 55 and 63 as the edge 53 moves to the right. Once the spool is in the detent position on the right, the maximum flow can be set by rotating flow control valve 57. When the pressure in chamber 55 exceeds the value set at relief valve 74, the detent piston 51 is kicked back and the spool 11 is released from the detented position.
  • valve 81 is turned through 90° so that communication is cut between the shuttle valve 65 and load sensing port 13 on the one side and chamber 64 on the other side.
  • the advantage of this is that when the load is being lowered by moving spool 11 to the left, the oil from the inlet chamber 55 flows into chamber 64 from where it is prevented from being fed back to the load sensing port 13 by valve 81.
  • the pump output pressure is not raised to the relief pressure of the system, as it would have been if valve 81 had been left open.
  • chamber 64 is deadheaded due to output port 24 being closed off. Thus, the pressure in chamber 64 cannot reach an equilibrium pressure corresponding to a load pressure.
  • oil flows into the single-acting cylinder 26, causing the piston to be extended. The sequence of events is as described previously for the case when the spool moves to the right.
  • the hydraulic valve in Figure 1 that has been described so far is designed so that a majority of the parts and machining operations can be used in an electro- hydraulic version shown in Figure 2.
  • the sleeve 42 used in Figure 1 is replaced by a simpler sleeve 82 in Figure 2.
  • the detent grooves are absent in this sleeve and 0-ring grooves 83 have been added.
  • the detent piston 51 is not used since the detent feature is provided at the control handle.
  • the detent kickout relief valve 74 is also deleted.
  • a pressure switch 84 is added in the electro-hydraulic valve to provide a signal to kick out the detent at the control handle at a preset pressure.
  • the manual flow control valve 57 is eliminated since it is possible to get the same function by electronic means.
  • the ends 85 and 86 of the spool 11 are used as pistons when the spool is to be moved by flow controlled by electrohydraulic means.
  • a feature of the valve embodying the present invention is the design of the load checks used to lock the hydraulic motors or cylinders attached to the valve at ports 23 and 24.
  • the poppet checks 34 and-35 and pilot poppet balls 39 and 48, with their corresponding seats, have very low leakage so that loads attached to the valve ;'are essentially held still and not allowed to leak down for long time periods when the valve spool 11 is at the neutral position. In valves without load checks, leak-down is minimized by holding the clearance between the spool 11 and its bore to the smallest feasible values.
  • the use of load checks allows a larger clearance between spool and bore and, correspondingly, larger tolerances during manufacture without concern about leak-down.
  • the main load checks 34 and 35 are controlled by a pilot system that is mechanically actuated by the sleeve 42 or 82 that moves with spool 11.
  • FIG. 3 shows a double-acting check valve 93 used to prevent a double-acting cylinder from slowly lowering a load due to leakage past the valve spool of a control valve (not shown).
  • the diagram indicates the fluid flow when the control valve is moved to extend the piston 96 of the double-acting cylinder 94. Fluid pressure entering through conduit 95 is exerted against the floating piston 92 of the check valve 93 which, because of its greater area, overcomes the spring 97 and relieves pressure behind the ball 98 in the return passage 99. This permits return flow to the control valve through the return conduit 101.
  • conduit 95 forces check ball 102 off its seat to extend the cylinder, that is, move the piston 96 upwardly as viewed in Figure 4.
  • the direction of movement of the piston 96 is reversed by reversing the direction of the fluid into and out of conduits 95, 101.
  • This hydraulically actuated load check system will function only when hydraulic system pressure is available, which means that loads can be lowered to a safe position only when the engine is on. If an operator forgets to lower the load before shutting off the engine, and if the control handle of the valve is then put into detent at the lowering position, a dangerous situation arises when the operator starts up the machine again. The load would suddenly fall because the control handle had been placed in......................... together
  • sleeve 42 Another feature of the valve described here is the use of sleeve 42 for many functions. This saves on the overall length of the valve and reduces the, In umber of parts.
  • Sleeve 4 2 provides the following functions.
  • Sleeve 82 used in the electrohydraulic valve, provides an additional function.
  • Yet another feature of the present valve is that most of the mechanical components can be used in both the mechanical and the electrohydraulic version of the valve.
  • a further feature is the provision of a single-acting mode in which the system pressure is not raised up to relief pressure when lowering a single-acting cylinder.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Catalysts (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
EP82306373A 1981-12-11 1982-12-01 Hydraulisches Ventil Withdrawn EP0081941A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US32996081A 1981-12-11 1981-12-11
US329960 1981-12-11

Publications (2)

Publication Number Publication Date
EP0081941A2 true EP0081941A2 (de) 1983-06-22
EP0081941A3 EP0081941A3 (de) 1984-08-01

Family

ID=23287750

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82306373A Withdrawn EP0081941A3 (de) 1981-12-11 1982-12-01 Hydraulisches Ventil

Country Status (3)

Country Link
EP (1) EP0081941A3 (de)
JP (1) JPS58102809A (de)
BR (1) BR8207135A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2264996A (en) * 1992-03-13 1993-09-15 John Burdon Pressurised-fluid valve assembly
US5621018A (en) * 1993-07-02 1997-04-15 Ciba Geigy Corporation Functionalized photoinitiators, macromers thereof, and the use thereof

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2686618B2 (ja) * 1988-04-20 1997-12-08 カヤバ工業株式会社 シリンダ制御装置

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2572705A (en) * 1950-05-04 1951-10-23 Deere Mfg Co Fluid control valve with selective float position
FR2312675B1 (fr) * 1975-05-29 1977-12-09 Bennes Marrel Sa Dispositif de commande d'un gros distributeur hydraulique, notamment pour engins de travaux publics
DE2729560C3 (de) * 1977-06-30 1980-08-07 Wabco Fahrzeugbremsen Gmbh, 3000 Hannover Einrichtung zum Fixieren eines Steuerschiebers

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2264996A (en) * 1992-03-13 1993-09-15 John Burdon Pressurised-fluid valve assembly
US5621018A (en) * 1993-07-02 1997-04-15 Ciba Geigy Corporation Functionalized photoinitiators, macromers thereof, and the use thereof

Also Published As

Publication number Publication date
EP0081941A3 (de) 1984-08-01
BR8207135A (pt) 1983-10-11
JPS58102809A (ja) 1983-06-18

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Effective date: 19850411

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Inventor name: RAJAGOPAL, GANESH

Inventor name: TALLIAN, RICHARD