GB2298291A - Electrohydraulic proportional control valve assemblies - Google Patents

Electrohydraulic proportional control valve assemblies Download PDF

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Publication number
GB2298291A
GB2298291A GB9603811A GB9603811A GB2298291A GB 2298291 A GB2298291 A GB 2298291A GB 9603811 A GB9603811 A GB 9603811A GB 9603811 A GB9603811 A GB 9603811A GB 2298291 A GB2298291 A GB 2298291A
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United Kingdom
Prior art keywords
valve
port
fluid
pressure
actuating
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Granted
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GB9603811A
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GB9603811D0 (en
GB2298291C (en
GB2298291B (en
Inventor
Stephen Brian Turner
David Franz Lakin
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Ultra Hydraulics Ltd
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Ultra Hydraulics Ltd
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Priority to GBGB9503854.3A priority Critical patent/GB9503854D0/en
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Publication of GB2298291A publication Critical patent/GB2298291A/en
Publication of GB2298291B publication Critical patent/GB2298291B/en
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/161Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/167Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load using pilot pressure to sense the demand
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02FDREDGING; SOIL-SHIFTING
    • E02F9/00Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20Drives; Control devices
    • E02F9/2025Particular purposes of control systems not otherwise provided for
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02FDREDGING; SOIL-SHIFTING
    • E02F9/00Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20Drives; Control devices
    • E02F9/22Hydraulic or pneumatic drives
    • E02F9/2221Control of flow rate; Load sensing arrangements
    • E02F9/2225Control of flow rate; Load sensing arrangements using pressure-compensating valves
    • E02F9/2228Control of flow rate; Load sensing arrangements using pressure-compensating valves including an electronic controller
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02FDREDGING; SOIL-SHIFTING
    • E02F9/00Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20Drives; Control devices
    • E02F9/22Hydraulic or pneumatic drives
    • E02F9/2278Hydraulic circuits
    • E02F9/2285Pilot-operated systems
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/161Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/163Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B21/00Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/08Servomotor systems incorporating electrically operated control means
    • F15B21/087Control strategy, e.g. with block diagram
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/305Directional control characterised by the type of valves
    • F15B2211/3056Assemblies of multiple valves
    • F15B2211/30565Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
    • F15B2211/3057Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve having two valves, one for each port of a double-acting output member
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/32Directional control characterised by the type of actuation
    • F15B2211/327Directional control characterised by the type of actuation electrically or electronically
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/505Pressure control characterised by the type of pressure control means
    • F15B2211/50509Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50536Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to the return line
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/515Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5157Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a return line
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/575Pilot pressure control
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/63Electronic controllers
    • F15B2211/6303Electronic controllers using input signals
    • F15B2211/6306Electronic controllers using input signals representing a pressure
    • F15B2211/6309Electronic controllers using input signals representing a pressure the pressure being a pressure source supply pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/63Electronic controllers
    • F15B2211/6303Electronic controllers using input signals
    • F15B2211/6306Electronic controllers using input signals representing a pressure
    • F15B2211/6313Electronic controllers using input signals representing a pressure the pressure being a load pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/63Electronic controllers
    • F15B2211/6303Electronic controllers using input signals
    • F15B2211/634Electronic controllers using input signals representing a state of a valve
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/665Methods of control using electronic components
    • F15B2211/6654Flow rate control

Abstract

An electrohydraulic proportional control valve assembly 1 for controlling a bidirectional fluid actuated device 7 has a first actuating port 4 for bidirectional fluid flow between the assembly and a first port of the device 7, a second actuating port 5 for bidirectional fluid flow between the assembly and a second port of the device 7, a pump port 15, 16 for input fluid flow from a pump 17, and a tank port 18, 19 for output fluid flow from a tank 20. The assembly 1 comprises a first and second spool valves 2 and 3 operable independently of each other. A position sensing arrangement 23, 24 is provided for supplying electrical position signals indicative of the actual positions of the spools 12, 13 of the first and second spool valves 2, 3 and a pressure sensing arrangement 26, 27, 28 and 29 is provided for supplying electrical pressure signals indicative of the fluid pressures in the first and second actuating ports 4, 5, the pump port 15, 16 and the tank port 18, 19. A servo control (not shown) controls the positions of the first and second spools 2, 3 in dependence on the electrical position and pressure signals and in response to an electrical demand signal provided in response to operator actuation, in order to set the throughflow cross-sections for fluid flow to effect the required control of the device 7.

Description

"Electrohydraullc Proportional Control Valve Assemblies" This invention relates to electrohydraulic proportional control valve assemblies for controlling fluid actuated devices.

It is known to utilise a proportional control valve assembly for controlling a fluid actuated device, such as a control ram for a lifting arm of an earth moving vehicle for example, in response to a demand signal supplied by an operator actuated joystick. Such a control valve assembly typically incorporates a main spool valve having a first actuating port for bidirectional fluid flow between the spool valve and a first port of the fluid actuated device, a second actuating port for bidirectional fluid flow between the spool valve and a second port of the fluid actuated device, a pump port for input fluid flow to the spool valve from a hydraulic pump, a tank port for output fluid flow from the spool valve to a hydraulic tank, and a spool for controlling the direction and rate of fluid flow between the first actuating port and the pump or tank port and the direction and rate of fluid flow between the second actuating port and the pump or tank port.

This control valve assembly may also incorporate a pressure compensator in the form of an auxiliary spool valve which is controlled so as to maintain a constant pressure drop across the spool of the main spool valve. Such a control valve assembly enables the fluid actuated device to be controlled independently of the load, so that, in the case of a control ram for a lifting arm of an earth moving vehicle for example, the arm is lifted or lowered at a substantially uniform rate regardless of the size of the load lifted by the arm or of variation in loading during lifting due to the structure of the arm itself. However such control valve assemblies are of complex mechanical construction, and this can render the control valve assemblies costly and difficult to manufacture.

Furthermore such control valve assemblies are capable of only limited control functions, and in particular are prone to malfunction in an over-running load condition, that is when external forces acting on the fluid actuated device due to gravity act in the same direction as the moving part of the fluid actuated device is being moved under hydraulic control.

It is proposed in International Published Application No. WO 93/01417 to provide such a control valve assembly with a change-over valve incorporating a position sensor which determines which of the two actuating ports connected to the fluid actuated device is at the higher pressure, and which supplies an electrical position signal indicative of which port is at the higher pressure to a processor which also receives an electrical pressure signal indicative of the higher pressure from a pressure sensor, as well as a directional signal indicative of the direction in which the spool is to be displaced from its neutral position by manual movement of an operator-actuated lever.The processor incorporates a comparator which establishes whether the input port as indicated by the directional signal is at the higher pressure, and provides an output signal to a positioning device for controlling the output of the pump in dependence on the result of this comparison and in accordance with the requirement of the load. Although such an assembly incorporates special control measures responsive to an over-running load condition, these measures operate only in response to actual movement of the spool on operator actuation, so that there is still a risk of malfunction in such an over-running load condition.

It is an object of the invention to provide a novel proportional control valve assembly which can be produced in a straightforward manner and which provides a large number of control functions.

According to the present invention there is provided an electrohydraulic proportional control valve assembly as defined in the accompanying claims.

Such a control valve assembly utilises adjustment of the position of the two valve members to control the flow rate and/or pressure at the ports of a fluid actuated device, such as a hydraulic cylinder or hydraulic motor, in dependence on the sensed valve member position, the sensed pressures in the ports and the sensed pump pressure and in response to the operator actuated demand signal, produced by operator actuation of a joystick for example. The valve members are continuously controlled by the servo control means in response to a continually updated actuating signal adapted to drive the valve members to positions corresponding to throughflow cross-sections appropriate to the required flow and pressure conditions and the desired operating mode of the fluid actuated device, and a large number of control functions can be provided by appropriate programming of the control circuitry.For example, the flow rate and/or pressure at the ports of the fluid actuated device may be controlled so that the device is adjustable at a uniform rate which is independent of the load, that is so that the rate of movement of the moving part of the device is not affected by variation of the applied load or supply pressure, either in a passive load condition or in an over-running load condition. Furthermore servo control of valve member position in dependence on the feedback position signals ensures highly accurate valve member positioning, without requiring either detailed analysis of valve characteristics or adjustment to take account of wear.

The provision of two separate valve means having separately movable valve members is advantageous as it enables differential opening and closing of the first and second actuating ports to effect control of the fluid actuated device. Independent control of the flow rate and/or pressure at the two ports of the fluid actuated device by such valve means thus enables operation of the fluid actuated device at a higher level of efficiency and safety than is possible in prior control arrangements in which efficiency losses are incurred as a result of the need to displace the moving part of the device against a back pressure.Furthermore, in the event of pressure overload, for example due to movement of the moving part of the device being blocked by external overloading, or where free floating of the load is required, one or both of the valve members may be opened to tank in order to vent the two sides of the fluid actuated device separately or simultaneously.

In order that the invention may be more fully understood, a preferred embodiment of control valve assembly in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a hydraulic circuit diagram of the assembly; Figure 2 is a diagrammatic sectional view through a part of the assembly; Figure 3 is a block diagram showing the electrical interconnections between various parts of the assembly; and Figure 4 is a logic diagram illustrating control functions of the assembly.

Referring to Figure 1 the illustrated electrohydraulic proportional control valve assembly 1 comprises first and second spool valves 2 and 3 connected to first and second actuating ports 4 and 5 for controllin.g fluid flow to opposite sides of a movable piston 6 of a fluid actuated device 7 in the form of a hydraulic cylinder or motor. The first and second spool valves 2 and 3 have spools 12 and 13 which are axially movable by pilot fluid flows controlled by electrically operated pilot actuator valves 44 and 45 (described more fully below with reference to Figure 2) between end positions in which the spool 12 or 13 places the corresponding actuating port 4 or 5 in communication with either a pump port 15 or 16 connected to the output of a pump 17 or a tank port 18 or 19 connected to a tank 20. The fluid supplied to the pilot actuator valves 44 and 45 is regulated by a pilot pressure regulator 14.

The spool 12 or 13 or each spool valve 2 or 3 is movable to effect opening of the spool valve 2 or 3 either to the pump port 15 or 16 or the tank port 18 or 19 over a throughflow cross-section which may be varied proportionately between a minimum opening value and a maximum opening value in dependence on the position of the spool 12 or 13. Furthermore both spools 12 and 13 are spring biased towards their neutral positions (in which they are shown in Figure 1), and position sensors 23 and 24 are provided for supplying electrical position signals indicative of the positions of the spools 12 and 13. In addition a pressure relief valve 25 is provided for venting the output of the pump 17 to the tank 20 in a manner which will be described in more detail below.Four pressure sensors 26, 27, 28 and 29 are provided for supplying electrical pressure signals PAS PBX PS and PT indicative of the fluid pressures in the first and second actuating ports 4 and 5, the pump port 15 or 16 and the tank port 18 or 19.

As shown diagrammatically on the right hand side of Figure 1, the pilot pressure regulator 14 may also serve to regulate pilot fluid supply to the pilot actuator valves of a further pair of spool valves, identical to the spool valves 2 and 3, for controlling supply of fluid to a further fluid actuated device 30. The two devices 7 and 30 may be two rams for controlling different linkage axes of an earth moving vehicle for example, and may be controlled by two valve slices in the assembly as described in more detail below.

Figure 2 shows a section through a valve slice part incorporating one of the first and second spool valves 2 and 3 and one of the associated pilot actuator valves 44 and 45, two such parts being provided in each valve slice. The pilot actuator valve 44 or 45 comprises a moving coil 35 fixed to a pilot spool 36 which is centred by two springs 37 and 38, the coil 35 being displaceable in an annular air gap 39 within a magnetic former 40 when a current is supplied to the coil 35 so as to provide magnetic interaction between the magnetic field associated with the current flow and the magnetic flux produced in the air gap 39 by the former 40.The pilot actuator valve 44 or 45 has two actuating ports 46 and 47 connected to the ends of the spool valve 2 or 3 by connecting conduits 48 and 49 respectively, as well as a tank port 70 connected to the tank and two pump ports 71 and 72 connected to pump either directly or by way of the pilot pressure regulator 14. The spool 12 or 13 of the spool valve 2 or 3 is centred by two springs 73 and 74 and has an extension 75 at one end enabling a position feedback signal dependant on the position of the spool 12 or 13 to be outputted by the position sensor 23 or 24.

With the spool 36 of the pilot actuator valve 44 or 45 in the neutral position as shown in Figure 2, only slight fluid leakage will take place through the pilot actuator valve, and hence the spool 12 or 13 of the main spool valve 2 or 3 will be held in its neutral position by the springs 73 and 74, as also shown in the figure. When a position control current is supplied to the coil 35, a force acts on the spool 36 so as to move it in one or other direction (dependant on the sense of the current) until an equilibrium position is reached in which the force is balanced by the forces exerted by the springs 37 and 38.If the spool 36 moves to the right as shown in the figure, this results in passages of a throughflow cross-section determined by the magnitude of the current being opened between the pump port 71 and the actuating port 46 and between the tank port 70 and the actuating port 47, with the result that a controlled displacement flow of pilot fluid is applied along the conduit 48 to the left hand end of the spool 12 or 13 of the main spool valve 2 or 3, and at the same time controlled venting of pilot fluid from the right hand end of the spool 12 or 13 takes place by way of the conduit 49 to tank.This causes the main spool 12 or 13 to be driven to the right as shown in the figure, with the speed of movement being determined by the degree of opening of the pilot actuator valve 44 or 45, until the position feedback signal outputted by the position sensor 23 or 24 indicates that the spool has been driven to the required position at which time the current to the coil 35 is cut off and the spool 36 of the pilot actuator valve 44 or 45 is returned to its neutral position by the springs 37 and 38. This results in movement of the main spool 12 or 13 being stopped so that the spool is held in the required position to which it has been driven by virtue of the fluid pressures acting on the two ends of the spool.

In practice the pilot actuator valve current is controlled in a complex way by the control circuitry in order to achieve optimum dynamic and position control characteristics, that is in order to rapidly drive the main spool 12 or 13 to the required position and in order to accurately retain the spool in that position for as long as necessary. This may in practice require energisation of the coil 35 by a small current under servo control even when movement of the main spool 12 or 13 is not required, so as to provide small fluid flows through the pilot actuator valve 44 or 45 to compensate for fluid leakage so as to retain the main spool 12 or 13 in the position to which it has been driven.However any current required to maintain the main spool in position will be very low, and will not adversely affect the generally low current consumption of the control circuitry which accurately monitors the position of the main spool valve 12 or 13 by means of the position sensor 23 or 24 at all times and controls the current to the coil 35 continuously so as to provide the required feedback control of the main spool position.

Since the moving coil 35 and the spool 36 to which it is fixed are of light construction, the coil 35 has low power consumption and the control circuitry requires only low power, low cost components. Furthermore high speed movement of the spool 36 is possible in response to the applied current under servo control, and rapid reversal of spool movement can be effected by reversal of the current in the coil 35 to cause the spool 36 to move in the opposite direction.Thus not only can the supply of fluid from the pump to the main spool 12 or 13, and corresponding venting of fluid from the main spool 12 or 13 to tank, be controlled rapidly so as to provide for accurate dynamic control of the main spool position in response to the position feedback signal, but also the control of the piston 6 of the fluid actuated device 7 can be effected with response times sufficient to enable highly advantageous control of the load in a manner which has not previously been possible with known control arrangements. For example, when the movement of the load is blocked, such as when the bucket of an excavator meets an obstruction, an appropriate pressure relief signal triggered by sensing of a pressure overload by one of the pressure sensors 26 and 27 can cause operation of the appropriate pilot actuator valve 44 or 45 so as to rapidly open one of the main spools 12 and 13 to tank, in order to reduce the pressure in the fluid actuated device in such a manner as to avoid damage due to over pressure. Such pressure relief occurs particularly rapidly due to the high speed dynamic response of the pilot actuator valves 44 and 45. Other control features enabled by the high speed dynamic response of the pilot actuator valves 44 and 45 under servo control will be discussed below.

Referring to Figure 3 the complete control valve assembly comprises, for example, a bank of two valve slices 50 and 51 of the general form described, each of which has a first actuating port 4 and a second actuating port 5 for connection to a respective fluid pressure actuated device (not shown), and an end slice 52 connected to the valve slices 50 and 51 and having a pump port 53 and a tank port 54. The end slice 52 serves to control the supply pressure of hydraulic fluid from a fixed displacement pump (not shown) connected to the pump port 53 in dependence on demand signals indicative of the demand for fluid to be supplied to the valve slices 50 and 51, in order to ensure that fluid is supplied only when required and in order to place the pump on standby if there is no requirement for fluid supply to the valve slices 50 and 51.During operator actuation the pressure relief valve 25 shown in Figure 1 is controlled in dependence on the load pressures sensed by the pressure sensors 26 and 27 to control the pressure of fluid supplied by the pump so that it exceeds the highest load pressure sensed by a predetermined amount. When no pressure load is sensed, the pressure relief valve 25 routes the fluid back to the tank at a nominal low pressure.

Alternatively, where a variable displacement pump is provided, the valve 25 may be configured to pilot the displacement control of the pump in such a way as to ensure supply of fluid in accordance with the requirements of the system. Although only two valve slices 50 and 51 are shown in Figure 3 for simplicity, it should be appreciated that a bank of four to ten valve slices is more likely to be provided in a practical embodiment.

Furthermore a control computer 55 is electrically connected to the valve slices 50 and 51 and to a joystick 56 by a serial communications network, so as to monitor operator actuation of the joystick 56, and so as to supply to the valve slices 50 and 51 pressure (P) or flow (Q) demand signals, and pressure-flow (P-Q) select signals. In addition the control computer 55 serves to supply initial set up data to the valve slices 50 and 51 on initial set up programing utilising a plug-in programmer 57, and also to provide error monitoring of the valve slices 50 and 51. If required, provision may be made for temporary connection to the valve slices 50 and 51 of a plug-in driver 58 for emergency operation of the valve slices 50 and 51.Also, if required, a health monitor display 59 may be connected to the control unit 55 to indicate correct operation of the valve slices 50 and 51.

The manner in which the control computer 55 is used to control the valve slices 50 and 51 in order to effect the required control of the fluid pressure actuated devices will now be briefly described with reference to Figure 4, it being understood that the control logic for carrying out the control functions described with reference to Figure 4 is incorporated in the valve slices 50 and 51 themselves and not in the control computer 55 which serves to provide overall system control. The control computer 55 supplies a pressure-flow (P-Q) select signal to each valve slice and a selection is made by a selector in each valve slice in dependence on this signal as to whether pressure control or flow control is to be effected.

Referring to Figure 4, it will be appreciated that the particular control mode in which the fluid actuated device is to be controlled is determined by the form of the select signal supplied by the control computer in dependence on the demand signal supplied by operator actuation of the joystick and/or control mode selector buttons or switches, as indicated by the control mode iteration loop 80 in the figure. If the flow control mode is selected, a flow demand signal Q, is supplied to a selector 81 which determines the required direction of fluid flow to the fluid actuated device, that is whether the flow is to port A or port B. In the event of zero flow being required, the control is effected so that both main spools are held in their neutral positions.In the event of flow to port A being required, a further selector 82 determines whether the pressure in the port A is greater than or less than the pressure in the port B, that is whether the load is to be treated as a passive load or an over running load. In the event of a passive load, the required throughflow cross-section a of the spool valve for controlling the flow to the port A is calculated at 83 by dividing the flow demand signal QEM by the value l((Ps - PA) and a constant of proportionality. A nominal downstream back pressure to be applied at the port B is set at 84, and the required positions of the two spools are then controlled at 85 by supplying control signals to the pilot actuator valve of the upstream spool valve in order to set the required throughflow cross-section a and by supplying control signals to the pilot actuator valve of the downstream spool valve so as to set the downstream back pressure at a predetermined level.

In the event of an overrunning load the required through flow cross-section a of the spool valve for controlling the flow through the port B is calculated at 86 by dividing the flow demand signal QEM by the value J (PB - PT) and the constant of proportionality (where PT is the sensed tank pressure or an assumed tank pressure where a tank sensor is not provided), and control of the filling of the upstream side of the piston of the fluid actuated device by way of the port A is set at 87, so that control of the required positions of the two spools at 88 provides for controlled metering out of fluid from the port B by appropriate setting of the through flow cross-section a of the downstream valve and controlled filling by way of the port A under control of the upstream valve.In view of the ability of the pilot actuator valves to switch rapidly between supply of fluid in one direction to the main spool valves and supply of fluid in the opposite direction, such a control arrangement enables discontinuous switching from a passive load condition to an overrunning load condition, as when a lifting arm of an earth moving vehicle is swung by the fluid actuated device through an over centre position so that the direction in which gravity acts on the load is in the same direction as piston movement, rather than in the opposite direction as it is prior to the over centre position being reached. The provision of a tank sensor enables more accurate control in the event of an overrunning load, and avoids any control discontinuities.

If the selector 81 determines that the required direction of fluid flow is to the port B of the fluid actuated device, then a similar series of control steps are carried out to the steps already described except that the control in relation to the ports A and B is reversed so that the calculations utilise the sensed pressure signal Pa in place of PA and vice versa. In each case the spool positions are continuously monitored by the position sensors, and the signals supplied to the pilot actuator valves are varied as required in dependence on the position feedback signals from the position sensors.

In the event that pressure control is selected, the pressures applied at the two ports A and B of the fluid actuated device are controlled in dependence on movement of the joystick by the operator such that the joystick movement determines the rate of change of pressure (magnitude and sense) applied to the load and, in the event of movement of the joystick being stopped, no further pressure change is applied to the load. Initially the pressure demand is calculated at 89 from the joystick input signal.

A selector 90 then determines whether the pressure demand requires the application of pressure to the port A or the port B. If the pressure demand is zero both port pressures are set to a nominal value. If the pressure demand requires application of pressure to the port A, a selector 91 first determines whether or not oscillating pressure is to be applied to the piston, for example in order to vibrate the load when a compaction mode has been selected.Depending on the result of this selection the required pressure at the port A is set to the demand pressure and the required pressure at the port B is set to a nominal value at 92, and the required control signals to the pilot actuator valves of the two spool valves are applied at 93 in order to control the positions of the main spools incrementally in dependence on the position feedback signals in order to set the required pressures in the ports A and B.

if the pressure demand requires application of pressure to the port B, a similar sequence of control steps is effected except that the demand pressure is applied to the port B and the pressure in the port A is set to a nominal value, that is a predetermined pressure above the sensed or assumed tank pressure. In the event that the compaction mode is selected, a sine wave varying cyclic demand pressure is added to the basic demand pressure so that the load is vibrated by the resulting pressure control.

The pressure control mode can be utilised with advantage in various operating conditions. For example, when lifting a load, the pressure control mode can be initiated so as to provide continuous pressure counterbalancing of the load and so as to allow the load to be manipulated manually with the application of only small pressures. Furthermore, if the load is an excavating arm carrying a bucket for digging through the ground for example, the applied pressure can be controlled so that, in the event of the bucket hitting an obstruction such an underground utility, a predetermined pressure limit will not be exceeded, and there is no danger of damage to the underground utility by the application of excess pressure.

If a float mode is selected by the operator by actuation of a special switch, both main spools are controlled at 94 so as to open both sides of the piston of the fluid actuated device to tank so as to enable free floating movement of the piston and any load coupled thereto.

Whilst the above described valve assembly utilizes first and second spool valves 2 and 3 for controlling fluid flow to and from the fluid actuated device, an alternative, non-illustrated valve assembly in accordance with the invention utilizes a pair of poppet valves in place of each such spool valve for controlling respectively the flow of fluid to the device from the pump by way of the associated actuating port and the flow of fluid from the device to the tank by way of the actuating port. In each case the pair of poppet valves associated with each actuating port is controlled by the pilot actuator valves to provide the required fluid flows in the various control modes.

Furthermore each of the pilot actuator valves may itself comprise a pair of poppet valves for controlling the fluid flows to and from the main valve or valves in response to current actuation of the moving coil.

Claims (15)

1. An electrohydraulic proportional control valve assembly for controlling a bidirectional fluid actuated device having first and second ports, the valve assembly having a first actuating port for bidirectional fluid flow between the valve assembly and the first port of the fluid actuated device, a second actuating port for bidirectional fluid flow between the valve assembly and the second port of the fluid actuated device, a pump port for input fluid flow to the valve assembly from a hydraulic pump, and a tank port for output fluid flow from the valve assembly to a hydraulic tank, the valve assembly comprising first valve means connected to the first actuating port, the pump port and the tank port for controlling the direction and rate of fluid flow between the first actuating port and the pump port and between the first actuating port and the tank port, and second valve means connected to the second actuating port, the pump port and the tank port for controlling the direction and rate of fluid flow between the second actuating port and the pump port and between the second actuating port and the tank port, the first valve means having a first valve member which is movable to vary the throughflow cross-section for fluid flow between the first actuating port and the pump or tank port, and the second valve means having a second valve member which is movable, independently of movement of the first valve member, to vary the throughflow cross-section for fluid flow between the second actuating port and the pump or tank port, position sensing means for supplying electrical position signals indicative of the actual positions of the first and second valve members, pressure sensing means for supplying electrical pressure signals indicative of the fluid pressures in the first and second actuating ports and the pump port, and servo control means for controlling the positions of the first and second valve members in dependence on the electrical position and pressure signals and in response to an electrical demand signal provided in response to operator actuation, in order to set the throughflow crosssections for fluid flow through the first and second valve means between the first actuating port and the pump or tank port and between the second actuating port and the pump or tank port to effect the required control of the fluid actuated device.
2. An assembly according to claim 1, wherein the first and second valve members are spools which are axially displaceable to vary the through flow crosssection for fluid flow between each actuating port and the pump or tank port.
3. An assembly according to claim 1 or 2, wherein the servo control means includes electrically operable pilot valve means for controlling the position of each of the valve members by applying a controlled displacement flow of pilot fluid to one part of the valve member, whilst at the same time applying controlled venting of pilot fluid from another part of the valve member, sufficient to drive the valve member to a required position in a first operating mode, and by subsequently discontinuing said displacement flow of pilot fluid to the valve member and said venting of pilot fluid so as to hold the valve member in said required position in a second operating mode.
4. An assembly according to claim 3, wherein the pilot valve means comprises a first pilot valve for effecting bidirectional axial movement of the first valve member, and a second pilot valve for effecting bidirectional axial movement of the second valve member independently of movement of the first valve member.
5. An assembly according to claim 4, wherein each pilot valve comprises an actuating coil movable relative to a magnetic former by the application of an electrical actuating current to the coil, and a valve element movable by the coil to simultaneously control application of pilot fluid to said one part of the valve member and venting of pilot fluid from said other part of the valve member.
6. An assembly according to any preceding claim, wherein the servo control means is operable, in a pressure control mode, to control the positions of the first and second valve members in response to an operator actuated electrical pressure demand signal corresponding to a required load pressure, in order to apply controlled fluid flow to one of the actuating ports and controlled venting of fluid from the other actuating port to produce a pressure difference across the fluid actuated device corresponding to the required load pressure.
7. An assembly according to any preceding claim, wherein the servo control means is operable, in a float mode, to control the positions of the first and second valve members in response to an operator actuated electrical float demand signal, in order to vent fluid from both actuating ports so as to allow free floating movement of a load coupled to the fluid actuated device.
8. An assembly according to any preceding claim, wherein the servo control means is operable, in a compaction mode, to control the positions of the first and second valve members in response to an operator actuated electrical compaction demand signal, in order to rapidly alternate the direction of fluid flow to the actuating ports so as to vibrate a load coupled to the fluid actuated device.
9. An assembly according to any preceding claim, wherein the servo control means is operable, in a pressure relief mode, to control the positions of the first and second valve members in response to an electrical pressure relief signal triggered by sensing of a pressure overload in one of the actuating ports by the pressure sensing means, in order to provide controlled venting of fluid from said one actuating port to relieve the pressure.
10. An assembly according to any preceding claim, wherein the pressure sensing means comprises a first pressure sensor for supplying a first electrical pressure signal indicative of the fluid pressure in the first actuating port, a second pressure sensor for supplying a second electrical pressure signal indicative of the fluid pressure in the second actuating port, a third pressure sensor for supplying a third electrical pressure signal indicative of the fluid pressure in the pump port, and a fourth pressure sensor for supplying a fourth electrical pressure signal indicative of the fluid pressure in the tank port, and wherein the servo control means is adapted to control the positions of the first and second valve members in dependence on the first, second, third and fourth electrical pressure signals.
11. An assembly according to any preceding claim, wherein a control computer is provided for monitoring the operator actuated electrical demand signals and for providing overall function control of the servo control means in dependence on the demand signals.
12. An assembly according to any preceding claim, which is of modular construction and includes a bank of valve slices assembled together and adapted to control a plurality of fluid pressure actuated devices.
13. An electrohydraulic proportional control valve assembly for controlling a fluid actuated device, the valve assembly incorporating an actuating port for fluid flow between the valve assembly and the fluid actuated device, a pump port for input fluid flow to the valve assembly from a hydraulic pump, a tank port for output fluid flow from the valve assembly to a hydraulic tank, and valve means for controlling the direction and rate of fluid flow between the actuating port and the pump port and between the actuating port and the tank port, the valve means incorporating at least one valve member which is movable to vary the throughflow cross-section for fluid flow between the actuating port and the pump or tank port, pressure sensing means for supplying electrical pressure signals indicative of the fluid pressures in the actuating port and the pump port, and servo control means for controlling the position of said at least one valve member in dependence on the electrical pressure signals and in response to an electrical demand signal provided in response to operator actuation, in order to set the throughflow cross-section for fluid flow through the valve assembly between the actuating port and the pump or tank port to effect the required control of the fluid actuated device, the servo control means including electrically operable pilot valve means for controlling the position of said at least one valve member by applying a controlled displacement flow of pilot fluid to the valve member sufficient to drive the valve member to a required position in a first operating mode, and by subsequently discontinuing said displacement flow of pilot fluid to the valve member so as to hold the valve member in said required position in a second operating mode.
14. An electrohydraulic proportional control valve assembly for controlling a fluid actuated device, the valve assembly incorporating an actuating port for fluid flow between the valve assembly and the fluid actuated device, a pump port for input fluid flow to the valve assembly from a hydraulic tank, a tank port for output fluid flow from the valve assembly to a hydraulic tank, and valve means for controlling the direction and rate of fluid flow between the actuating port and the pump port and between the actuating port and the tank port, the valve means incorporating at least one valve member which is movable to vary the throughflow cross-section for fluid flow between the actuating port and the pump or tank port, first pressure sensing means for supplying a first electrical pressure signal indicative of the fluid pressure in the actuating port, second pressure sensing means for supplying a second electrical pressure signal indicative of the fluid pressure in the pump port, third pressure sensing means for supplying a third electrical pressure signal indicative of the fluid pressure in the tank port, and servo control means for controlling the position of said at least one valve member in dependence on the first, second and third electrical pressure signals and in response to an electrical demand signal provided in response to operator actuation, in order to set the throughflow cross-section for fluid flow through the valve assembly between the actuating port and the pump or tank port to effect the required control of the fluid actuated device.
15. An electrohydraulic proportional control valve assembly substantially as hereinbefore described with reference to the accompanying drawings.
GB9603811A 1995-02-25 1996-02-22 Electrohydraulic proportional control valve assemblies Expired - Lifetime GB2298291C (en)

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GBGB9503854.3A GB9503854D0 (en) 1995-02-25 1995-02-25 Electrohydraulic proportional control valve assemblies

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GB2298291A true GB2298291A (en) 1996-08-28
GB2298291B GB2298291B (en) 1998-06-10
GB2298291C GB2298291C (en) 2008-02-26

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GB9603811A Expired - Lifetime GB2298291C (en) 1995-02-25 1996-02-22 Electrohydraulic proportional control valve assemblies

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JP (2) JPH11501106A (en)
KR (1) KR100432381B1 (en)
CN (1) CN1070974C (en)
DE (1) DE69602923T3 (en)
DK (1) DK0809737T4 (en)
GB (2) GB9503854D0 (en)
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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0884482A1 (en) * 1996-02-28 1998-12-16 Komatsu Ltd. Control device for hydraulic drive machine
GB2328524A (en) * 1997-08-22 1999-02-24 Ultronics Limited An electro hydraulic proportional control valve assembly
WO2002075162A1 (en) 2001-03-21 2002-09-26 Bucher Hydraulics Gmbh Control valve
EP1259937A2 (en) * 1999-04-23 2002-11-27 Clark Equipment Company Features of main control computer for a power machine
WO2005005842A1 (en) * 2003-07-09 2005-01-20 Hydac System Gmbh Hydraulic system
GB2406363A (en) * 2003-09-24 2005-03-30 Sauer Danfoss Aps Supply and tank hydraulic valves with position sensor
EP1669613A1 (en) * 2004-12-07 2006-06-14 Volvo Construction Equipment Holding Sweden AB Hydraulic control circuit and method thereof
WO2009075613A1 (en) * 2007-12-12 2009-06-18 Volvo Construction Equipment Ab A method for when necessary automatically limiting a pressure in a hydrualic system during operation
WO2009150062A2 (en) * 2008-06-13 2009-12-17 Zf Friedrichshafen Ag Hydraulic supply system for feeding a hydraulic consumer having at least one consumption zone
US20110202232A1 (en) * 2007-10-11 2011-08-18 Jochen Busch Hydraulic Lift System And Control Method
US8291925B2 (en) 2009-10-13 2012-10-23 Eaton Corporation Method for operating a hydraulic actuation power system experiencing pressure sensor faults
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Families Citing this family (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10138389A1 (en) * 2001-08-04 2003-02-20 Bosch Gmbh Robert Electro-hydraulic device for controlling a double-acting motor
US6763661B2 (en) 2002-05-07 2004-07-20 Husco International, Inc. Apparatus and method for providing vibration to an appendage of a work vehicle
WO2004020840A1 (en) * 2002-08-28 2004-03-11 Bucher Hydraulics Gmbh Hydraulic drive for a control valve
DE10259146A1 (en) * 2002-12-18 2004-07-15 Georg Sebode Lift with a hydraulic drive
DE10340506B4 (en) * 2003-09-03 2006-05-04 Sauer-Danfoss Aps Valve arrangement for controlling a hydraulic drive
DE10340504B4 (en) 2003-09-03 2006-08-24 Sauer-Danfoss Aps Valve arrangement for controlling a hydraulic drive
DE10340505B4 (en) * 2003-09-03 2005-12-15 Sauer-Danfoss Aps Valve arrangement for controlling a hydraulic drive
DE102004050294B3 (en) 2004-10-15 2006-04-27 Sauer-Danfoss Aps Hydraulic valve arrangement
DE102005022891A1 (en) 2005-04-05 2006-10-12 Bosch Rexroth Aktiengesellschaft Hydraulic control arrangement and control block
DE102005045035B4 (en) * 2005-09-21 2007-07-12 Wessel-Hydraulik Gmbh Hydraulic circuit arrangement for supplying a double-acting hydraulic consumer
CN100370149C (en) * 2006-01-24 2008-02-20 东北大学 Constant backpressure and proportion controlled sinter apparatus HAGC System
JP4703419B2 (en) * 2006-01-31 2011-06-15 カヤバ工業株式会社 Control circuit for hydraulic actuator
US7487707B2 (en) 2006-09-27 2009-02-10 Husco International, Inc. Hydraulic valve assembly with a pressure compensated directional spool valve and a regeneration shunt valve
US8359849B2 (en) * 2009-04-07 2013-01-29 Eaton Corporation Control of a fluid circuit using an estimated sensor value
DE102009033645A1 (en) 2009-07-17 2011-01-20 Robert Bosch Gmbh Hydraulic control arrangement
US8375989B2 (en) * 2009-10-22 2013-02-19 Eaton Corporation Method of operating a control valve assembly for a hydraulic system
EP2638297B1 (en) * 2010-11-08 2015-12-30 Robert Bosch GmbH Hydraulic or pneumatic drive for actuating a fitting comprising a control valve or selector valve
US8857168B2 (en) 2011-04-18 2014-10-14 Caterpillar Inc. Overrunning pump protection for flow-controlled actuators
DE102011114241B4 (en) * 2011-06-09 2014-09-04 Sms Meer Gmbh Hydraulic drive device, hydraulic output stage of a hydraulic servo-control valve, servo-control valve and powder press
CN102536194B (en) * 2011-12-13 2014-05-28 中国石油集团长城钻探工程有限公司 Hydraulic-driven automatic bit feeding control system with constant bit pressure
CN102535571A (en) * 2012-02-17 2012-07-04 上海三一重机有限公司 System and method of regeneration control based on double spools for hydraulic excavator
CN102587443A (en) * 2012-02-23 2012-07-18 上海三一重机有限公司 Multiway valve hydraulic control system of crawler excavator
CN102678663B (en) * 2012-05-30 2015-05-20 上海三一重机有限公司 Oil cylinder for excavator and excavator with cylinder
US9145660B2 (en) 2012-08-31 2015-09-29 Caterpillar Inc. Hydraulic control system having over-pressure protection
CN102888873B (en) * 2012-09-12 2015-03-11 徐州徐工挖掘机械有限公司 Device for improving linear running performance of excavator during compound action
CN103122648B (en) * 2012-12-28 2015-06-17 上海三一重机有限公司 Multi-way valve hydraulic control system, rectilinear walking control valve and excavator
CN103256334B (en) * 2013-04-28 2016-06-22 潍坊威度电子科技有限公司 Double-act-ing hydraulic J-Horner tractor suspension hydraulic system based on electromagnetic digital valve
DK2811174T3 (en) * 2013-06-04 2020-10-12 Danfoss Power Solutions Aps Steering arrangement for a hydraulic system and a method for controlling a hydraulic system
US8977445B2 (en) * 2013-06-18 2015-03-10 Caterpillar Inc. System and method for dig detection
CN104564863B (en) * 2014-12-26 2017-02-22 大连理工大学 Electrohydraulic control system for rotation motion of pipe splicing machine
JP6324347B2 (en) * 2015-06-01 2018-05-16 日立建機株式会社 Hydraulic control equipment for construction machinery
CN108138810B (en) 2015-10-08 2020-10-16 沃尔沃建筑设备公司 Slide valve
US9713307B1 (en) 2016-01-21 2017-07-25 Deere & Company Electrohydraulic dynamic spool position control for a proportional valve in a work vehicle
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US10330126B2 (en) 2016-12-16 2019-06-25 Caterpillar Inc. Fan control system with electro-hydraulic valve providing three fan motor operational positions
CN107387477B (en) * 2017-07-20 2018-11-06 徐州工业职业技术学院 A kind of leading controller for guiding valve, hydraulic cylinder control loop
CN108953306B (en) * 2018-08-26 2021-01-08 燕山大学 Direct-drive type volume control electro-hydraulic servo control system of duplex pump

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US33846A (en) * 1861-12-03 Improved mode of heating molds
EP0038128A1 (en) * 1980-04-04 1981-10-21 General Signal Corporation Electro-hydraulic servo activator system
DE3347000C2 (en) * 1983-12-24 1992-06-04 Robert Bosch Gmbh, 7000 Stuttgart, De
JP2828490B2 (en) * 1990-06-19 1998-11-25 日立建機株式会社 Load sensing hydraulic drive circuit controller
US5138838A (en) * 1991-02-15 1992-08-18 Caterpillar Inc. Hydraulic circuit and control system therefor
DE4122164C1 (en) * 1991-07-04 1993-01-14 Danfoss A/S, Nordborg, Dk
JPH05256303A (en) * 1992-01-15 1993-10-05 Caterpillar Inc Hydraulic control apparatus

Cited By (24)

* Cited by examiner, † Cited by third party
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EP0884482A4 (en) * 1996-02-28 1999-05-19 Komatsu Mfg Co Ltd Control device for hydraulic drive machine
EP1798346A2 (en) * 1996-02-28 2007-06-20 Komatsu Ltd. Control device for hydraulic drive machine
EP0884482A1 (en) * 1996-02-28 1998-12-16 Komatsu Ltd. Control device for hydraulic drive machine
GB2328524A (en) * 1997-08-22 1999-02-24 Ultronics Limited An electro hydraulic proportional control valve assembly
GB2328524B (en) * 1997-08-22 2000-07-26 Ultronics Limited An electro hydraulic proportional control valve assembly
EP1259937A4 (en) * 1999-04-23 2006-05-24 Clark Equipment Co Features of main control computer for a power machine
EP1259937A2 (en) * 1999-04-23 2002-11-27 Clark Equipment Company Features of main control computer for a power machine
WO2002075162A1 (en) 2001-03-21 2002-09-26 Bucher Hydraulics Gmbh Control valve
WO2005005842A1 (en) * 2003-07-09 2005-01-20 Hydac System Gmbh Hydraulic system
GB2406363B (en) * 2003-09-24 2006-08-16 Sauer Danfoss Aps Hydraulic valve arrangement
GB2406363A (en) * 2003-09-24 2005-03-30 Sauer Danfoss Aps Supply and tank hydraulic valves with position sensor
US7252030B2 (en) 2004-12-07 2007-08-07 Volvo Construction Equipment Holding Sweden Ab Hydraulic control circuit and method thereof
EP1669613A1 (en) * 2004-12-07 2006-06-14 Volvo Construction Equipment Holding Sweden AB Hydraulic control circuit and method thereof
US20110202232A1 (en) * 2007-10-11 2011-08-18 Jochen Busch Hydraulic Lift System And Control Method
WO2009075613A1 (en) * 2007-12-12 2009-06-18 Volvo Construction Equipment Ab A method for when necessary automatically limiting a pressure in a hydrualic system during operation
US8695333B2 (en) 2007-12-12 2014-04-15 Volvo Construction Equipment Ab Method for when necessary automatically limiting a pressure in a hydraulic system during operation
WO2009150062A2 (en) * 2008-06-13 2009-12-17 Zf Friedrichshafen Ag Hydraulic supply system for feeding a hydraulic consumer having at least one consumption zone
WO2009150062A3 (en) * 2008-06-13 2010-03-18 Zf Friedrichshafen Ag Hydraulic supply system for feeding a hydraulic consumer having at least one consumption zone
US8291925B2 (en) 2009-10-13 2012-10-23 Eaton Corporation Method for operating a hydraulic actuation power system experiencing pressure sensor faults
EP3078622A4 (en) * 2013-12-20 2017-08-02 Xuzhou Heavy Machinery Co., Ltd. Apparatus and method for detecting and protecting telescopic oil cylinder of crane
US10196245B2 (en) 2013-12-20 2019-02-05 Xuzhou Heavy Machinery Co., Ltd. Apparatus and method for detecting and protecting telescopic oil cylinder of crane
EP3670931A1 (en) * 2018-12-17 2020-06-24 Hyva Holding BV A hydraulic control system

Also Published As

Publication number Publication date
WO1996027051B1 (en) 2001-04-12
KR19980702483A (en) 1998-07-15
GB2298291C (en) 2008-02-26
JPH11501106A (en) 1999-01-26
DK0809737T3 (en) 1999-11-22
JP2006177561A (en) 2006-07-06
EP0809737A1 (en) 1997-12-03
CN1070974C (en) 2001-09-12
DE69602923T3 (en) 2008-05-21
EP0809737B1 (en) 1999-06-16
KR100432381B1 (en) 2004-09-16
DK0809737T4 (en) 2008-01-07
CN1175988A (en) 1998-03-11
WO1996027051A1 (en) 1996-09-06
DE69602923D1 (en) 1999-07-22
DE69602923T2 (en) 1999-12-09
EP0809737B2 (en) 2007-09-19
GB9603811D0 (en) 1996-04-24
GB2298291B (en) 1998-06-10
GB9503854D0 (en) 1995-04-19

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