EP0097007A2 - Hydraulisches Steuersystem - Google Patents

Hydraulisches Steuersystem Download PDF

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Publication number
EP0097007A2
EP0097007A2 EP83303198A EP83303198A EP0097007A2 EP 0097007 A2 EP0097007 A2 EP 0097007A2 EP 83303198 A EP83303198 A EP 83303198A EP 83303198 A EP83303198 A EP 83303198A EP 0097007 A2 EP0097007 A2 EP 0097007A2
Authority
EP
European Patent Office
Prior art keywords
pressure
valve
control system
chamber
load
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.)
Ceased
Application number
EP83303198A
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English (en)
French (fr)
Other versions
EP0097007A3 (de
Inventor
William Richards Price
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Individual
Original Assignee
Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0097007A2 publication Critical patent/EP0097007A2/de
Publication of EP0097007A3 publication Critical patent/EP0097007A3/de
Ceased legal-status Critical Current

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    • 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
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/08—Servomotor systems incorporating electrically operated control means
    • F15B21/087—Control strategy, e.g. with block diagram
    • 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
    • F15B9/00—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member
    • F15B9/02—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member with servomotors of the reciprocatable or oscillatable type
    • F15B9/08—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member with servomotors of the reciprocatable or oscillatable type controlled by valves affecting the fluid feed or the fluid outlet of the servomotor
    • F15B9/09—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member with servomotors of the reciprocatable or oscillatable type controlled by valves affecting the fluid feed or the fluid outlet of the servomotor with electrical control means

Definitions

  • This invention relates to a hydraulic control system. More especially, this invention relates to a hydraulic control system for use in either open or closed loop modes, for the bi-directional regulation of speed, acceleration and deceleration of hydraulically-actuated loads, as typically encountered in hydraulic elevators and machines used in mechanical handling, construction, agricultural and machine tool industries.
  • An aim of the present invention is to overcome or reduce these disadvantages and to provide an improved, simpler and energy-efficient hydraulic control system capable of operating in either closed or open loop systems over a wide range of loads and load speeds, in a manner which is independent of load magnitude and, in the case of operation in the closed loop mode, independent of both load magnitude and oil viscosity.
  • this invention provides a hydraulic control system for regulation of fluid flow rate, in which the fluid flow rate to and from a load actuator is modulated by electric current in a single electro-magnetic device such that the flow rate is independent of load magnitude when the system is used without load velocity feedback and such that the flow rate is independent of both load magnitude and fluid viscosity when the system is used with load velocity feedback.
  • control system utilises only two main hydraulic elements.
  • instantaneous load speed may be regulated in proportion to the magnitude of signal applied by an electric current function generator to a single electric control element which serves for both directions of load movement.
  • instantaneous load speed may be regulated in proportion to the signal magnitude applied by an electric signal function generator to an electric summing device, which is also connected electrically with the single electric conrol element and a transducer of load speed.
  • valve block and covers containing the various elements of the control system are indicated by reference numbers la, lb and lc.
  • An actuating cylinder 28 is connected to the valve assembly at a port 31, through which fluid is either directed to or from the cylinder.
  • a valve 2 in addition to being a load holding valve, also performs the function of a flow-regulating valve.
  • the valve 2 is urged on to its seat 5 by a spring 3 in addition to the force created by the fluid pressure in the cylinder acting upon the full diameter of the valve 2.
  • a pressure regulating valve 8 meters flow from a common flow chamber 39 across a land 86 to a reservoir 30, via an annulus 33 and an exhaust port 34, and its position is dictated by the interaction of springs 11 and 12 and fluid pressure acting on the ends of the pressure regulating valve 2 and on two pistons 9 and 10.
  • a poppet valve 26 is operated by a solenoid 25 which, in turn, is activated by externally applied electric current.
  • the poppet valve 26 is connected on its upstream side with fluid under load pressure in a chamber 32.
  • the poppet valve 26 is connected to pilot pistons 23a, 23b and 6.
  • the pilot pistons 23a and 23b operate valves 22a and 22b, the former for conditioning pressure in a flow valve spring chamber 7 and the latter for supplying load pressure from the chamber 32 to either chamber 14 or 16 at pre-determined phases in the system operation.
  • the pilot piston 6 controls the operation of the flow regulating valve 2.
  • a sequence valve 24 is biased to the right hand position by a spring 59 and is connected at its other end to a supply port chamber 20.
  • the sequence valve 24 serves to either isolate or communicate the supply chamber 20 with a chamber 13, or to isolate or to communicate load pressure with the chamber 16.
  • a check valve 17 operates in a guide 18 and is urged onto its seat by a spring 19.
  • the check valve 17 isolates a common flow chamber 39 when a pump 29 is not supplying fluid to the system.
  • Restrictors 35, 36, 37 and 38 fulfill an important function in the operation of the system, the purpose of which will be explained later.
  • Restrictors 99 and 100 in the pressure regulating valve 8 form damping devices.
  • a valve 89 is an overload relief valve.
  • the sequence valve 24 is biased to the right by the spring 59, so that channels 66 and 69 are isolated and channels 68 and 70 are connected by means of annulus 63 and ports 64 and 65 in the valve 24 and its bush.
  • the valve 8 is randomly positioned.
  • the springs 11 and 12 are relaxed.
  • trigger switches external to the hydraulic control system are operated. These trigger the current function generator to generate an electric current profile, typically as Figure 9 part 'A' for up and down load movement.
  • Control pressure is applied to the pilot piston 6 via a channel 77, and to pilot pistons 23a and 23b via the channels 75 and 53.
  • the opposite sides of the pilot pistons 6, 23a and 23b are maintained at reservoir pressure by channels 79, 55 and 57 respectively, all of which connect with annular chamber 33 and thence to the fluid reservoir.
  • the pressure regulating valve 8 may be conditioned by the selective actuation of the pistons 9 or 10 to regulate pressure in the common flow chamber 39 to be respectively either a fixed value above load pressure or a fixed value below load pressure, the former condition being applicable to upwards load movement and the latter to downwards load movement.
  • the pump 29 For upwards load movement, the pump 29 is energised and the oil which is displaced flows via check valve 17, common flow chamber 39, chamber 33 and tank port 34 to the reservoir.
  • the chamber 14 is at reservoir pressure, being vented to the reservoir via chanel 68, sequence valve 24, channel 70, orifice 37, channel 85 and tank port 34.
  • the piston 9 As the chamber 13 is at reservoir pressure, the piston 9 is able to move to the left, exhausting oil in the chamber 13 to the reservoir via orifice 36, channel 84 and tank port 34.
  • the spring 11 remains relaxed and so does not exert an appreciable force on the valve 8.
  • valve 8 if not disposed fully left when the pump is energised, is instantaneously so positioned because any pressure which tends to develop in the flow chamber 39 is communicated via channel 82 to the chamber 15, where it results in a force acting on the valve 8 which moves it left until it abuts a bushing 104.
  • the valve 8 in the full left position presents an ultra-low impedance to oil flow from the chamber 39 to the chamber 33 and hence to reservoir. Pressure at the pump is determined initially by that needed to open the check valve 17, which may be determined to be extremely low. Thus the pump prime mover is started in a virtually completely unloaded mode.
  • the pump pressure existing upstream of the check valve 17 is applied via channel 67 to the right end of the sequence valve 24, the left end of which is vented to the reservoir via channel 79, chamber 33 and tank port 34.
  • the sequence valve 24 may be designed to move full left virtually simultaneously with the pump starting to operate, so that the channels 66 and 69 previously isolated, become connected, and the channels 68 and 70 previously connected become isolated.
  • Connections of the channels 66 and 69 cause pump pressure to be applied to the chamber 13, where it acts on the left side of the piston 9, the right side of which is at reservoir pressure by virtue of its connection with the port 34 and the channel 84.
  • control pressure in response to the increasing electric current flowing from the function generator to the solenoid 25, gradually increases, it reaches a value which is sufficient to separate the poppet 22b from its seat. This connects the load pressure in the chamber 32, via channels 54 and 58, to the chamber 14 where it acts on the left end of the valve spool 8.
  • valve spool 8 now has load pressure acting on its left hand end and chamber 39 pressure - virtually reservoir pressure - acting on its right hand end.
  • the valve spool 8 thus moves to the right, increasing the impedance to oil flow from the chamber 39 to 33 and the reservoir port 34.
  • the increased impedance raises chamber 39 pressure and hence pump pressure, which is applied to the piston 9.
  • the chamber 16 is at reservoir pressure, so the piston 10 gradually moves to the right as chamber 39 pressure, connected with the chamber 15 via channel 82, increases. This leaves the spring 12 in a relaxed condition.
  • the diameter of the piston 9 in the chamber 13 has a larger area than the diameter in the chamber 14 so, under the action of the increasing pump pressure, the piston 9 moves to the right until it registers against the abuttment in sleeve 104.
  • the piston 9 positions the left end of the spring 11 in a fixed axial relationship with the flow metering land 86 of the pressure regulating valve 8, which is thus conditioned to function as a pressure reducing valve, whereby it will maintain the pressure in the chamber 39 at a nominally fixed value above load pressure, variations in the pressure difference being dependent on the rate of the spring 11 which may be designed to be substantially constant over the operating stroke of the spool 8. This pressure difference will be maintained irrespective of variations in load pressure, so that oil flow rate from the chamber 39 across the flow regulating valve 2 is dependent only on the flow area created when the valve 2 is separated from its seat 5.
  • the pilot piston 23a whose left end is vented to reservoir via channels 55 and 84 and tank port 34, moves left under the action of control pressure applied to its right end and so separates the poppet 22a from its seat. This action causes the spring in chamber 7, previously at load pressure, to be vented to reservoir pressure. oil flow from the load actuator to reservoir is limited to a very low rate by the orifice 35.
  • the flow regulating valve 2, now biased closed only by the spring 3, is thus able to respond smoothly to control pressure variations applied to the pilot piston 6.
  • the load actuator will accelerate, move at constant speed, then decelerate, move at slow speed and stop, as an analogue of the current in the solenoid 25.
  • Control pressure is generated as previously described and applied to all pilot pistons and chambers in an identical manner as for upward load movement.
  • the spring chamber 7 is vented to reservoir in the same way as for upward load movement.
  • upstream of check valve 17 will be at reservoir level and hence the sequence valve 24 will remain disposed to the right under the action of the spring 59.
  • the channels 68 and 70 will be connected via the ports 64 and 65 and annulus 63 in the sequence valve 24.
  • the piston 9 is able to move fully left, as the chamber 13 is at reservoir pressure, so ensuring that the spring 11 is relaxed.
  • the flow regulating valve 2 is thus able to respond to control pressure variations applied to the pilot piston 6, in principle the same as for upward load movement.
  • the orifices 36 and 37 serve the dual functions of limiting flow rate to the reservoir when the chambers 13 and 16 are pressurised, and allowing both chambers to vent when the pistons 9 or 10 move away from their respective abuttments.
  • the relief valve 89 provides an overload relief function for the system when the pump 29 is activated. Pressure from the common flow chamber 39 is transmitted via channel 82 to the chamber 15. If the pressure exceeds the predetermined limit, the pressure regulating valve 8 is urged to the left. The same pressure is transmitted to the chamber 13 but since the head of the piston 9 is larger than its second diameter in the chamber 14, the piston 9 will be urged to the right.
  • Pressure in the chamber 14 then becomes equal to the excess pressure in the chamber 15 and is exhausted through the relief valve 89, thus allowing the valve 8 to move to the left into the space created by the displaced fluid and enabling excess pressure in the chamber 39 to exhaust across the annulus 33 back to the reservoir.
  • Figure 4 illustrates a simple alternative construction for the pistons 9 and 10 in which a single piece form has been replaced by a two piece design consisting of a large piston 71 and a smaller piston and spring guide 72.
  • shims 101 are added inside the spring recess between the valve springs 11 and 12 and their respective pistons 9 and 10 to adjust the spring tension.
  • Figure 6 indicates yet another construction in which the pistons 9 and 10 are encapsulated by a sliding bush 93 and an end cap 95 and a sliding bush 96 and an end cap 97 respectively.
  • the position of the sliding bushes and end caps can thus be modified externally to change the influence of the springs 11 and 12 by means of adjusting screws 94 and 98 without dismantling the pressure regulating valve.
  • Instantaneous load speed is electrically transduced at 8.1 and its signal is applied to one element of a differential comparator system 8.2, the second element of which is connected with a signal function generator 8.3, and the third element of which is connected, via an amplifier, with the solenoid 25.
  • trigger switches external to the control system are operated. These trigger the function generator 8.3 to generate electric signal profiles typically as Figure 9 part 'A' and 'B' for up and down load movement respectively.
  • the differential comparator connected with the solenoid 25 receives a signal which is the arithmetic sum of the function generator signal and the load speed transducer signal.
  • an alternative construction for a control pressure pilot valve to that described above with reference to the poppet valve 26 is a 3-way valve comprising a spool located in a closed housing, with three lands spaced longitudinally along the spool and arranged to create two hydraulically separate chambers with the housing.
  • T One of the chambers
  • P the other chamber
  • P the load port 31
  • a poppet-type flow check valve non-return valve
  • the end of the spool nearest the "T” chamber is acted upon by a spring which gives a biasing force which tends to move the spool towards an electro-magnetic device located at the opposite end of the spool and so arranged that the armature of the electro-magnetic device is in contact with the end of the spool nearest the "P" chamber.
  • the centre land of the spool overlaps a hole in the housing disposed perpendicularly to the spool, the hole being hydraulically connected to a chamber at the end of the spool to which the biasing force is applied and hydraulically connected to channels 53,56,75,77.
  • the spool between the centre land and the land at the electro-magnetic device end of the spool is tapered such that its diameter where it joins the centre land is smaller than that where it joins the land at the electro-magnetic device end of the spool.
  • the poppet-type check valve is arranged so that its polar axis is nominally perpendicular to and in the same plane as the axis of the 3-way valve spool.
  • the poppet is arranged so that hydraulic pressure from port 31 presses the poppet onto its seat, thus effectively sealing the load pressure from the "P" chamber.
  • the poppet is lightly spring biased onto its seat in the housing and the stem of the poppet is so arranged in relation to the tapered portion of the 3-way valve spool that a slight longitudinal movement of the spool towards the biasing force end will lift the poppet from its seat, thus admitting pressure from port 31 to the "P" chamber.
  • the functional operation of the alternative control pressure pilot valve is as follows. Electric current applied to the electro-magnetic device creates a force which displaces the spool which in turn lifts the poppet, so admitting pressure (i.e. load) to the "P" chamber. Continued displacement of the spool as a result of increasing electric current eventually eliminates the overlap of the centre land of the spool with the hole in the housing which is connected to channels 53,56,75,77 and the end of the spool to which the biasing force is applied. The pressure acting on the end of the spool creates a force which acts in opposition to that exerted at the other end of the spool by the electro-magnetic device.
  • the spool adopts a position of equilibrium determined by the opposing hydraulic, electro-magnetic and biasing forces, such that the hydraulic pressure existing at the force-biased end of the spool will be a function of the electric current in the electro-magnetic device.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Servomotors (AREA)
  • Fluid-Pressure Circuits (AREA)
EP83303198A 1982-06-15 1983-06-02 Hydraulisches Steuersystem Ceased EP0097007A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8217309 1982-06-15
GB8217309 1982-06-15

Publications (2)

Publication Number Publication Date
EP0097007A2 true EP0097007A2 (de) 1983-12-28
EP0097007A3 EP0097007A3 (de) 1984-08-01

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EP83303198A Ceased EP0097007A3 (de) 1982-06-15 1983-06-02 Hydraulisches Steuersystem

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EP (1) EP0097007A3 (de)
GB (1) GB2121990B (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113446278A (zh) * 2021-06-28 2021-09-28 于化杰 一种液压换向阀

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3031846A (en) * 1961-04-05 1962-05-01 David E Wiegand Hydraulic servo
FR1605286A (de) * 1964-04-16 1974-04-05
US3455210A (en) * 1966-10-26 1969-07-15 Eaton Yale & Towne Adjustable,metered,directional flow control arrangement
CH444601A (de) * 1966-12-13 1967-09-30 Beringer Hydraulik Gmbh Steuervorrichtung für hydraulisch betriebene Einrichtungen
GB1200911A (en) * 1967-02-23 1970-08-05 Churchill Charles Ltd Improvements in hydraulic flow controllers
US3410308A (en) * 1967-12-05 1968-11-12 Moog Inc Moving coil electrohydraulic servovalve
US3742981A (en) * 1972-02-24 1973-07-03 Sanders Associates Inc Flow control valve with single spool second stage
DE2234131C3 (de) * 1972-07-12 1975-04-03 Messerschmitt-Boelkow-Blohm Gmbh, 8000 Muenchen Stabilisierungseinrichtung zur Dämpfung hochfrequenter Schwingungen an einer hydraulischen Servosteuerung
GB1465674A (en) * 1973-02-26 1977-02-23 Sperry Rand Ltd Electrically-operated fluid actuator
DE2658928A1 (de) * 1976-12-24 1978-07-06 Beringer Hydraulik Gmbh Hydraulische steuerung
DE2962702D1 (en) * 1978-08-25 1982-06-24 Dewandre Co Ltd C Improvements relating to hydraulic control systems
US4222409A (en) * 1978-10-06 1980-09-16 Tadeusz Budzich Load responsive fluid control valve
GB2046953B (en) * 1979-03-22 1983-02-23 Trw Inc Fluid flow control
IT1129054B (it) * 1980-01-08 1986-06-04 Fiat Ricerche Regolatore di portata per circuiti idraulici
DE3042015C2 (de) * 1980-11-07 1987-02-26 Reinhard Ing.(grad.) 4050 Mönchengladbach Kucharzyk Elektrohydraulisches Proportionalventil

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113446278A (zh) * 2021-06-28 2021-09-28 于化杰 一种液压换向阀
CN113446278B (zh) * 2021-06-28 2022-07-22 温岭市富力泵业有限公司 一种液压换向阀

Also Published As

Publication number Publication date
GB2121990A (en) 1984-01-04
EP0097007A3 (de) 1984-08-01
GB2121990B (en) 1985-11-13
GB8315137D0 (en) 1983-07-06

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