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EP3584451A1 - Flüssigkeitsdruckvorrichtung mit axial entgegengesetzten kolben - Google Patents

Flüssigkeitsdruckvorrichtung mit axial entgegengesetzten kolben Download PDF

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Publication number
EP3584451A1
EP3584451A1 EP19177777.0A EP19177777A EP3584451A1 EP 3584451 A1 EP3584451 A1 EP 3584451A1 EP 19177777 A EP19177777 A EP 19177777A EP 3584451 A1 EP3584451 A1 EP 3584451A1
Authority
EP
European Patent Office
Prior art keywords
component
piston
casing
inward
flow
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Withdrawn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
EP19177777.0A
Other languages
English (en)
French (fr)
Inventor
Peter Lauterslager
Kees Van Hooft
Steven Caffall FINCH
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.)
Caterpillar Work Tools BV
Original Assignee
Caterpillar Work Tools BV
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 Caterpillar Work Tools BV filed Critical Caterpillar Work Tools BV
Publication of EP3584451A1 publication Critical patent/EP3584451A1/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Withdrawn legal-status Critical Current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
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/1409—Characterised by the construction of the motor unit of the straight-cylinder type with two or more independently movable working pistons
    • 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
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/24—Other details, e.g. assembly with regulating devices for restricting the stroke
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/765—Control of position or angle of the output member
    • F15B2211/7653—Control of position or angle of the output member at distinct positions, e.g. at the end position
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/765—Control of position or angle of the output member
    • F15B2211/7656—Control of position or angle of the output member with continuous position control
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/77—Control of direction of movement of the output member
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/77—Control of direction of movement of the output member
    • F15B2211/7708—Control of direction of movement of the output member in one direction only
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/78—Control of multiple output members

Definitions

  • This disclosure relates to hydraulic or pneumatic systems comprising axially opposed pistons arranged in a common chamber.
  • EP 1 350 960 A1 discloses a fluid pressure actuator with independently moveable, first and second drive elements, which may be configured as pistons with a pressurised fluid channel extending through one of the piston rods.
  • Such arrangements make it possible to move two components mounted on the respective pistons simultaneously or sequentially, and so may be useful for example where the components are configured as clamps and work in opposed relation to apply an inwardly or outwardly directed clamping force to a workpiece.
  • the configuration of the pistons limits the range of applications, particularly in situations where space is limited.
  • the assembly comprises an actuator including first and second pistons having heads which slide in axially opposed relation in a common chamber defined by a casing.
  • a first component is fixed to or part of the casing, while a second component is fixed to or part of the second piston.
  • the first piston is fixed to the support while the casing and the second piston are operable to move the first and second components, each independently of the other in opposite, inward and outward directions relative to the support.
  • a control system is arranged and operated to control a flow of pressurised fluid to and from the chamber, either (A) to move the first component and the casing to a first limit position, and then to restrain the first component and the casing in the first limit position while moving the second component and the second piston selectively in the inward and outward directions; or (B) to move the second component and the second piston to a second limit position, and then to restrain the second component and the second piston in the second limit position while moving the first component and the casing selectively in the inward and outward directions.
  • an assembly comprises an actuator 1 having a first piston 30, a second piston 20, and a cylinder or casing 10 defining a chamber 11.
  • the first piston comprises a first piston head 31 fixed to a first piston rod 32
  • the second piston comprises a second piston head 21 fixed to a second piston rod 22.
  • the piston heads are slidably and sealingly received in axially opposed relation in the chamber 11 with the piston rods extending slidably and sealingly through the axially opposed end walls 12, 13 of the casing so that the chamber 11 is divided into three volumes V1, V2, V3.
  • the first volume V1 is defined between the first piston head 31 and the adjacent end wall 12, the third V3 between the second piston head 21 and the adjacent end wall 13, and the second V2 between the two piston heads 31, 21.
  • the actuator may be of generally conventional design with the casing, chamber and pistons being cylindrical as well known in the art, and the two piston heads and piston rods being of equal diameter as shown.
  • the piston rod 32 of the first piston 30 is fixed to a support 2 which defines the frame of reference for the system so that all movement takes place relative to the support 2.
  • the assembly further includes a first component 100 which is fixed to or part of the casing 10, and a second component 200 which is fixed to or part of the second piston 20, for example, being fixed to a distal end of the second piston rod 22 as shown schematically in Fig. 1 .
  • first and second components may comprise any functional parts and may be arranged in any position as required by the particular application of the assembly.
  • the actuator 1 is operable to move each of the first and second components 100, 200 independently of the other and relative to the support 2 in an inward direction D1 towards the support 2 and in an opposite, outward direction D2 away from the support 2.
  • all movements are to be understood as taking place along the common central axis of the chamber and pistons in either the inward direction D1 or outward direction D2, although it should be understood of course that the system may have other degrees of freedom (for example, it may be angularly adjustable via a pivotable attachment to the support 2) as required by the particular application.
  • the assembly further comprises a control system 300 which is arranged to control a flow of pressurised fluid 3 to and from the chamber 11 to cause relative movement between each of the first and second pistons and the chamber.
  • a control system 300 which is arranged to control a flow of pressurised fluid 3 to and from the chamber 11 to cause relative movement between each of the first and second pistons and the chamber.
  • the actuator is taken to be a hydraulic actuator, with the pressurised fluid being a substantially incompressible liquid such as any conventional hydraulic fluid, and the assembly is described and illustrated accordingly.
  • the actuator may be a pneumatic actuator, the pressurised fluid being a compressed gas having sufficient pressure to restrain the respective system components in their limit positions, in which case the system components including the control system may be adapted mutatis mutandis as known in the art.
  • Fig. 1 schematically illustrates three fluid connections 301, 302, 303 respectively to each of the three volumes V1, V2, V3 of the chamber, wherein the three fluid connections 301, 302 and 303 are configured by the control system in accordance with a first pump/drain configuration C1.
  • a pump/drain configuration means a configuration in which one of the respective volumes V1, V2, V3 is connected to a drain or tank so that when the fluid 3 contained therein is pressurised by an external force applied to the second piston or the casing it can relieve the pressure in that volume by flowing to the drain or tank, while another one of the respective volumes V1, V2, V3 is supplied with pressurised fluid 3 from a pump so as to urge the second piston or casing in motion against an external force.
  • the fluid connection to the other one of the three volumes V1, V2, V3 may be closed so that the fluid contained therein cannot escape under pressure and so may be placed in compression by an external applied force and so resist movement of the second piston or casing responsive to that force.
  • the fluid connection 301 to the first volume V1 represents the drain; the fluid connection 302 to the second volume V2 is closed; and the fluid connection 303 to the third volume V3 represents the pump.
  • This configuration is reproduced as configuration C1 in Fig. 9 , with some other possible permutations of the same three fluid connections (drain, closed, pump) being shown respectively in Figs. 10 - 12 .
  • Fig. 1 shows all three fluid connections as entering the chamber via the cylindrical wall of the casing.
  • the fluid connection 303 to the central volume V2 may extend through one of the pistons, conveniently the first piston 30, as illustrated in the example arrangement of Figs. 14 - 16 , which makes it possible for the range of movement of each of the pistons relative to the casing to overlap with that of the other piston, as illustrated in Figs. 5 - 8 .
  • Fig. 1 also shows four limit stops, i.e. abutments, L1, L2, L3 and L4.
  • Each limit stop may be arranged as a fixed part of the assembly or as a movable or removable part which has at least one use position in which it is fixed at least in the inward or outward direction D1 or D2 relative to the support 2 so as to mechanically restrain the movement of the casing or second piston in that respective direction.
  • Fig. 1 For clarity, in the schematic arrangement of Fig. 1 the limit stops are shown as abutting respectively the first or second component 100, 200 to define limit positions as shown in Figs. 5 - 8 .
  • each of the limit stops may be operatively engaged, respectively by the first component or the casing or by the second component or the second piston, without direct abutment - for example, via a series of functionally interdependent, intermediate components which react the motion of the respective first component/casing or second component/second piston against the respective limit stop.
  • each of the limit stops may be configured as another functional part of the assembly.
  • limit stops L2 and L3 may be internal to the chamber, being defined respectively by the abutment of the second piston head against the fixed, first piston head, or the abutment of the first end wall 12 of the chamber against the fixed, first piston head.
  • first component 100 and casing 10 will be referred to together as the first element 1000
  • second component 200 and second piston 20 will be referred to together as the second element 2000.
  • the control system 300 is arranged to control the flow of pressurised fluid 3 to and from the three volumes V1, V2, V3 of the chamber to move the first element 1000 and second element 2000 independently of each other and relative to the first piston 30 and support 2.
  • the first and second elements may be moved to define any or all of four possible states, represented respectively in Figs. 5 - 8 in which:
  • the first element 1000 is operatively engaged with limit stop L1 in the first limit position
  • the second element 2000 is operatively engaged with limit stop L4 in the fourth limit position.
  • the first element 1000 is operatively engaged with limit stop L1 in the first limit position
  • the second element 2000 is operatively engaged with limit stop L2 in the second limit position.
  • the first element 1000 is operatively engaged with limit stop L3 in the third limit position
  • the second element 2000 is operatively engaged with limit stop L2 in the second limit position.
  • the first element 1000 is operatively engaged with limit stop L3 in the third limit position
  • the second element 2000 is operatively engaged with limit stop L4 in the fourth limit position.
  • the two possible limit positions of the first element 1000 defined respectively by limit stops L1 and L3 will be referred to, respectively as L1 and L3
  • the two possible limit positions of the second element 2000 defined respectively by limit stops L2 and L4 will be referred to, respectively as L2 and L4.
  • the control system may be operable in a first mode A to move the first element 1000 to a first limit position, e.g. L1 or L3, and then to restrain the first element 1000 in the first limit position L1 or L3 while moving the second element 2000 selectively in the inward and outward directions D1, D2.
  • a first limit position e.g. L1 or L3
  • control system may be operable in a second mode B to move the second element 2000 to a second limit position, e.g. L2 or L4, and then to restrain the second element 2000 in the second limit position L2 or L4 while moving the first element 1000 selectively in the inward and outward directions D1, D2.
  • a second limit position e.g. L2 or L4
  • the control system may be operable in a second mode B to move the second element 2000 to a second limit position, e.g. L2 or L4, and then to restrain the second element 2000 in the second limit position L2 or L4 while moving the first element 1000 selectively in the inward and outward directions D1, D2.
  • control system is operable selectively in both the first mode A and the second mode B.
  • either one of the first and second elements 1000, 2000 may be restrained in a respective limit position without being under an external applied load; which is to say, as long as no external force is applied to it, the restrained element will remain in a static position while the other respective element is urged in motion by the pressurised fluid 3.
  • an external load may cause the first or second element 1000, 2000 to move if the load is applied in a direction to reduce a respective volume V1, V2, V3 of the chamber which is connected to drain, and if there is no mechanical abutment (limit stop L1, L2, L3 or L4) to constrain movement in that direction.
  • the respective element 1000 or 2000 will be restrained only by ambient (atmospheric) pressure and so will yield when the load exceeds this value.
  • to restrain under load (or when loaded) in a particular direction means that the respective component is restrained in a fixed position when loaded in the indicated direction by the working fluid placed in compression by the load, and/or by mechanical abutment of the solid assembly parts.
  • the working fluid will prevent movement in response to the applied load up to a limit imposed by the fluid pressure or (for a substantially incompressible working fluid) the failure limit of the system components.
  • the assembly may be arranged to restrain either or both of the first and second elements 1000, 2000 in a selected limit position while under load, either by means of one or more limit stops such as limit stops L1, L2, L3, L4, or without the use of limit stops.
  • Figs. 2, 3 and 4 illustrate various arrangements of the control system 300 which make it possible to restrain the first or second element 1000, 2000 under load in a selected limit position without the use of limit stops.
  • the control system is arranged to restrain the flow of pressurised fluid 3 from the chamber 11 in proportional relation to the flow of pressurised fluid 3 to the chamber 11.
  • fluid 3 leaving a respective volume V1, V2, V3 of the chamber is arranged to urge a proportional volume of fluid 3 to enter another respective volume V1, V2, V3.
  • a pump 40 which receives the fluid 3 from V1 and supplies it to V3, while V2 is closed.
  • the fluid drives the first element 1000 in the outward direction D2 while the second element 2000 is restrained.
  • a similar effect is achieved by two pumps 41, 42 connected together by a common shaft and driven in rotation by a motor.
  • the external force F urges fluid 3 from V1 via pump 41 to the tank 50, which in turn drives pump 42 in rotation to urge a proportional volume of fluid 3 from the tank 50 into V3.
  • Each pump may be a positive displacement pump. It will be understood that the pump connections and closed connection can be connected to the three volumes V1, V2, V3 as required to obtain the desired relative movement of the two elements 1000, 2000 in either direction D1 or D2. If one of the connected volumes contains a piston rod and the other does not, or if the piston rods are of different diameters, then the two pumps 41, 42 can be configured with different positive displacement volumes which are matched to the displacement of each respective volume of the actuator for the same linear movement of the system elements 1000, 2000.
  • Fig. 4 shows how a similar arrangement can be obtained using a separate actuator 60 comprising a chamber 61 and piston 62 which is driven axially under power to transfer the pressurised fluid 3 between the two volumes on either side of the piston head 63 and the respective volumes V1, V2 or V3 of the chamber 11.
  • the piston 62 may comprise one or two piston rods to match the volumes of the chamber 61 to the respective volumes V1, V2, V3 of the chamber 11.
  • An arrangement such as that shown in any of Figs. 2, 3 and 4 may be used to restrain the flow of pressurised fluid 3 from the chamber 11 in proportional relation to the flow of pressurised fluid 3 to the chamber 11, with the fluid connections to the three chamber volumes V1, V2, V3 configured suitably:
  • each limit position may be selectively variable so that it can be freely selected at any position of each of the elements 1000, 2000 along their range of movement in the direction D1 or D2.
  • an operator of the system could select a limit position at which to stop (limit) the movement of the respective element 1000, 2000 during one stroke of the element, and restrain the element in that limit position while moving the other respective element, and then select a different limit position during the next movement.
  • each element 1000, 2000 can be moved to a selected limit position anywhere in its range of movement and then restrained in that position under load while moving the other respective element 1000 or 2000 in either direction D1, D2.
  • a compensating means such as an accumulator may be provided to compensate for a difference in the volume displacement of the two sides of the system (respectively, urging fluid to flow into the chamber 11, and allowing fluid to flow out of the chamber 11).
  • the compensating means may deliver or accumulate a small volume of fluid 3 on one side of the circuit relative to the other, so as to maintain freedom of movement without developing excessive fluid pressure.
  • the volume of the compensating means may be adjustable or continuously variable and may correspond to a small degree of freedom of movement of the respective elements 1000, 2000, which may be regarded as a linear range within which each limit position is defined in the direction D1 or D2.
  • limit stops as described above to define the respective limit positions, it is also possible to restrain a respective one of the elements 1000, 2000 under load while moving the other respective element 1000, 2000 in the desired direction, using a simple pump/drain circuit configuration which does not require accurately matched positive displacement volumes on each side of the pumped circuit.
  • Table 1 indicates how the novel mechanism including none, one, or more than one of the respective limit stops (indicated by their respective number L1, L2, L3, L4) can restrain each of the casing and the second piston in a fixed position when loaded in the indicated inward or outward direction, while the respective other one of the casing and the second piston is moved by a fluid circuit in which one side of the circuit is connected to drain substantially without resistance as indicated respectively in circuit configurations C1, C2, C3 and C4..
  • limit stops L1, L2, L3, L4 it is not necessary for the limit stops L1, L2, L3, L4 to be arranged externally of the casing to engage the elements 1000, 2000 in direct abutment as illustrated for the sake of simplicity and ease of understanding in Figs. 5 - 8 .
  • the limit stops L1, L2, L3, L4 are taken to be external to the casing as illustrated, while the abutment of the first piston head 31 against the inward end wall 12 of the casing is taken into account as equivalent to limit stop L3, and the abutment of the second piston head 21 against the first piston head 31 is taken into account as equivalent to limit stop L2.
  • control system when a first limit position is defined by a first abutment or limit stop L1 to limit movement of the first element 1000 in the inward direction D1, the control system is operable in a simple pump/drain configuration C3, C4:
  • control system when a second limit position is defined by a second abutment or limit stop L4 to limit movement of the second element 2000 in the outward direction D2, the control system is operable in a simple pump/drain configuration C1, C2:
  • Fig. 13 by providing a combination of three limit stops or abutments, it is possible to arrange the control system to selectively reconfigure the fluid connections 301, 302, 303 in each of the four pump/drain fluid configurations C1, C2, C3 and C4 responsive to sensing a change in the pressure or flow rate of the pressurised fluid 3 to define a repeatable and reversible sequence of movement of the first and second elements 1000, 2000 between the four states S1, S2, S3, S4.
  • control system is arranged:
  • the control system 300 may include a valve arrangement 310 and a flow reversing control which in the illustrated example is formed by a valve 350.
  • the flow reversing control is operable (e.g. by an electrical switch, not shown, connected to a solenoid 351, as shown) to supply the flow of pressurised fluid 3 to the valve arrangement 310, selectively in opposite, first and second flow directions, represented in Fig. 13 by the two possible states of the valve 350.
  • the valve arrangement 310 is arranged:
  • valve arrangement 310 is arranged:
  • the valve arrangement 310 includes two time delay valves 320, 330 and functions as follows.
  • V3 is fed by the pump and retracts the second element 2000 in the inward direction D1 to limit position L2.
  • Fluid pressure in V3 urges the first element 1000 in the outward direction D2, generating fluid pressure in V1 which is applied to time delay valve 330.
  • This initiates the timer function of time delay valve 330 which then opens after a period determined by the volume of its accumulator 331, allowing fluid in V1 to flow to the tank or drain 50 so that the first element 1000 moves in the outward direction D2 to limit position L3.
  • the solenoid 351 is then operated to reverse the flow direction from valve 350, applying fluid pressure to time delay valve 320 and activating its timer function. Fluid 3 also flows to V1 and applies fluid pressure to time delay valve 330, activating its timer function.
  • time delay setting of time delay valve 320 is shorter than of time delay valve 330, so that time delay valve 320 opens first, allowing pressurised fluid 3 to flow to V2.
  • Valve 315 is then activated, preventing fluid 3 from flowing to V1 and to time delay valve 330 which has not yet reached the end of its time delay period and so remains closed.
  • the fluid pressure in V2 urges the second element 2000 to move in the outward direction D2.
  • Valve 314 is also closed when time delay valve 320 has opened, closing V1 and so preventing the first element 1000 from moving in the outward direction D2.
  • the assembly is configured by way of example to control the transmission of shaft power between three shafts 400, 401, 402.
  • the pressurised fluid 3 is arranged to flow through a flowpath 302 which extends through the first piston 30 and opens through the first piston head 31 into the second volume V2 within the region of the chamber 11 between the first and second piston heads 31, 21 so that the respective ranges of movement of the first and second elements 1000, 2000 overlap.
  • the first shaft 400 comprises a shoulder L1 which defines a first limit stop to limit movement of the first element 1000 in the inward direction D1.
  • the first component 100 comprises a splined sleeve 101 rotating in a bearing 102 and slidable between a first limit position ( Fig. 14 ) defined by the abutment of the sleeve 101 against the shoulder L1, and a third limit position ( Fig. 16 ) defined by the abutment of an internal stop 410 of the casing 10 against the first piston head 31 which defines the third limit stop L3 to restrain movement in the outward direction D2.
  • the second piston rod 22 is extended to support a gear 403 mounted on a rotary bearing 404 which together define the second component 200.
  • the rod 22 slides through an axial bearing 405 which forms the fourth limit stop L4, limiting movement of the second element 2000 in the outward direction D2 by abutment of the bearing 404 against the bearing 405 in a fourth limit position ( Fig. 14 ).
  • a second limit stop L2 is defined by an internal stop 406 mounted on the first piston head 31, the second piston head 21 engaging the internal stop 406 in to limit its movement in the inward direction D1 in a second limit position ( Fig. 15 ).
  • the first and second elements are moved axially to selectively couple and decouple the three transmission shafts as described above and as shown in sequence in Figs. 14 , 15 , and 16 .
  • the novel assembly may be used to provide controlled, independent movement of two functionally related components at the distal end of an outwardly extending assembly, wherein both ranges of movement are defined relative to a single support at a proximal end of the assembly, and thus on the same side of the support.
  • the ranges of the first and second elements 1000, 2000 may be arranged to overlap by providing a flowpath for the pressurised fluid to flow through the first piston and first piston head into the central volume of the chamber.
  • Each of the first and second elements 1000, 2000 may be restrained in a limit position while under load in one or both directions, while moving the other respective element independently and reversibly in the desired direction.
  • the limit position may be selected freely at any point in the range of motion of the respective component.
  • a simple pump/drain circuit configuration may be adopted, which may further provide a repeatable sequence of movements which is reversible simply by reversing the direction of flow from the pump.
  • a fluid pressure actuator comprises axially opposed first and second pistons slidably arranged in a common casing.
  • a first component is fixed to or part of the casing while a second component is fixed to or part of the second piston.
  • the first piston is fixed to a support.
  • the actuator is operable to restrain either of the first and second components in a fixed position while moving the other independently and relative to the support.
  • first and second components may be coaxial or collinear.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Damping Devices (AREA)
  • Actuator (AREA)
EP19177777.0A 2018-06-06 2019-05-31 Flüssigkeitsdruckvorrichtung mit axial entgegengesetzten kolben Withdrawn EP3584451A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1809328.6A GB2574590B (en) 2018-06-06 2018-06-06 Fluid pressure apparatus with axially opposed pistons

Publications (1)

Publication Number Publication Date
EP3584451A1 true EP3584451A1 (de) 2019-12-25

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EP19177777.0A Withdrawn EP3584451A1 (de) 2018-06-06 2019-05-31 Flüssigkeitsdruckvorrichtung mit axial entgegengesetzten kolben

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111306141A (zh) * 2020-04-03 2020-06-19 广东志成电液科技有限公司 一种极限位置可调的液压缸及极限位置调整方法
WO2022208547A1 (en) * 2021-03-31 2022-10-06 Svakalpan Engineering Designs (Opc) Pvt. Ltd. A pnuematic actauting system and method for actuation

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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FR1252062A (fr) * 1959-11-20 1961-01-27 Circuit hydraulique à butée de fin de course par équilibre dynamique à fuite
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