EP0069128A1 - Valve actuator - Google Patents

Valve actuator

Info

Publication number
EP0069128A1
EP0069128A1 EP19820900213 EP82900213A EP0069128A1 EP 0069128 A1 EP0069128 A1 EP 0069128A1 EP 19820900213 EP19820900213 EP 19820900213 EP 82900213 A EP82900213 A EP 82900213A EP 0069128 A1 EP0069128 A1 EP 0069128A1
Authority
EP
European Patent Office
Prior art keywords
piston
cylinder
actuator
pressure
valve
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Withdrawn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
EP19820900213
Other languages
German (de)
French (fr)
Inventor
Wallace Mccormack
David Bowditch
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.)
CAMTORC Ltd
Original Assignee
CAMTORC Ltd
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 CAMTORC Ltd filed Critical CAMTORC Ltd
Publication of EP0069128A1 publication Critical patent/EP0069128A1/en
Withdrawn legal-status Critical Current

Links

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
    • F15B11/06Servomotor systems without provision for follow-up action; Circuits therefor involving features specific to the use of a compressible medium, e.g. air, steam
    • F15B11/072Combined pneumatic-hydraulic systems
    • F15B11/0725Combined pneumatic-hydraulic systems with the driving energy being derived from a pneumatic system, a subsequent hydraulic system displacing or controlling the output element
    • 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
    • F15B11/02Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/028Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
    • F15B11/032Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force by means of fluid-pressure converters
    • 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
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/21Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge
    • F15B2211/212Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge the pressure sources being accumulators
    • 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
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/21Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge
    • F15B2211/214Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge the pressure sources being hydrotransformers
    • 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
    • F15B2211/30505Non-return valves, i.e. check valves
    • 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
    • F15B2211/30525Directional control valves, e.g. 4/3-directional control 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
    • F15B2211/30Directional 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
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051Linear output members
    • F15B2211/7053Double-acting output members
    • 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
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76Control of force or torque of the 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
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/77Control of direction of movement of the output member
    • F15B2211/7716Control of direction of movement of the output member with automatic return

Definitions

  • This invention relates to a valve actuator of the kind comprising a pressurised fluid-operated piston and cylinder assembly in which the piston is arranged to actu- ate the valve member of a valve.
  • the actuator in accordance with the invention may be employed to actuate linearly actuable valves, for example gate valves.
  • a pressure fluid-operated actuator of the kind comprising a housing with a cylindrical bore, a piston assembly comprising a pair of spaced-apart pistons coupled together for simultaneous sliding movement within said cylindrical bore, a cam situated between the two pistons and secured to a valve actuating shaft rotatable about an axis fixed relative to the housing and disposed substan- tially at right angles to the longitudinal axis of said cylindrical bore with the peripheral surface of the cam engaging the confronting surfaces of the two pistons of said piston assembly, and means for supplying pressurised fluid to a space in said cylindrical bore for moving said piston assembly within the cylindrical bore.
  • the actuator may be of the single-acting type, in which rotation of the valve actuating shaft in only one direction, for example in the opening direction of the valve, can be effected by supplying pressurised fluid to said space, spring means then being provided for effecting rotation of the valve actuating shaft in the opposite direction.
  • the actuator may be of the double-acting type, so ' that rotation of the valve actuating shaft in either direction can be effected by supplying pressurised fluid to different spaces in said cylindrical bore.
  • spring means may be provided to assist rotation of the shaft in the closing direction of the valve, so that the valve can be closed in the event of failure of the pressurised fluid supply.
  • actuator in the form of a single- or double-acting piston and cylinder assembly, in which the linear movement of the piston rod of the actuator actuates the linearly movable valve member of the valve.
  • This type of actuator may also comprise spring means for effecting or assisting movement of the piston, usually in the valve closing direction.
  • rotary and linear valve actuators are usually operated by a pressurised fluid supply (generally compress- ed air) at a pressure of up to about 10 kg/cm (gauge).
  • a pressurised fluid supply generally compress- ed air
  • pressure up to about 10 kg/cm (gauge)
  • torques of up to 1000 Nm or thrusts of up to 500 kg the actuator does not have an unacceptably large size.
  • the present invention aims to provide a valve actuator of the kind referred to which does not have the disadvan ⁇ tage just referred to.
  • a valve actuator compris- ing an actuator cylinder, an actuator piston movable in the cylinder, a valve actuating member actuable by said piston, and means for supplying pressurised fluid to said cylinder for moving said piston in said cylinder, is characterised in that said pressurised fluid-supplying means comprises a pressure intensifier driven by a pressur ⁇ ised medium at a first pressure and arranged to deliver said pressurised fluid to said actuator cylinder at a pressure higher than that of said pressurised medium.
  • Said pressure intensifier may comprise first and second piston and cylinder assemblies having their cylin ⁇ ders axially aligned with one another* and their pistons mechanically connected, ' the piston of said first piston and cylinder assembly having a larger area than the piston of said second piston and cylinder assembly, and means for supplying said pressurised medium at said first pres ⁇ sure to said first piston and cylinder assembly, said second piston and cylinder assembly constituting the means for supplying pressurised fluid at said higher pressure to said actuator cylinder.
  • Said first piston and cylinder assembly may be double-acting, so that the piston of said first piston and cylinder assembly may be reciprocated in its cylinder by said pressurised medium.
  • said pressure intensifier comprises a first double-acting piston and cylinder assembly having a piston of a first diameter D which is mechanically conn ⁇ ected to the piston of a second double-acting piston and cylinder assembly having a piston of a second diameter d which is smaller than D, the cylinders of the two assem ⁇ blies having their axes aligned with one another.
  • the piston of the first assembly is reciprocated in its cylin ⁇ der by supplying a pressurised fluid medium, for example compressed air, to its cylinder at a pressure p_, which is the aforesaid first pressure.
  • the pressure £ may, for example, be in the range of from 4 to 10 kg/cm (gauge).
  • This reciprocation of the piston of the first assembly results in reciprocation of the piston of the second assem- bly and the creation of a pressure P in the fluid in the aforesaid pressurised fluid-supplying means, the pressure P, which is the aforesaid second pressure, being higher than the pressure £ in accordance with the equation:
  • the pressure P created in said pressurised fluid-supplying means will be 25£. Therefore, for example, if the first piston and cylinder assembly is actuated with compressed air at a
  • the pressurised fluid at the pressure P is contained in a closed, or sub- stantially closed, circuit which includes the second piston and cylinder assembly of the pressure intensifier and the actuator cylinder of the valve actuator.
  • the pressurised fluid at the pressure P may be a fluid of the same or a different nature from the pressur- ised -medium at the pressure £.
  • the second piston and cylinder assembly is single-acting instead of double-acting, it is possible to use one and the same pressurised fluid in both of the piston and cylinder assem ⁇ blies of the pressure intensifier.
  • a single pressure intensifier may be common to a plurality of valve actuators, the actuator cylinders of the various actuators then being connected in parallel with the pressure intensifier.
  • Figure 1 is a schematic sectional view of a first embodiment of a valve actuator in accordance with the ⁇ invention, 'and
  • FIGS 2 and 3 are schematic sectional views of parts of two modified forms of the embodiment of Figure 1.
  • the valve actuator shown in Figure 1 comprises a housing 1 having a circular cylindrical bore 2 therein and end closure members 3 and 4. Slidable within the bore 2 is a piston assembly, generally designated by the reference numeral 5, which comprises two pistons 6, 7 held together in spaced-apart relationship by rods 8.
  • a valve actuating shaft 9 is rotatably mounted in the wall of the housing 1, the axis of the shaft being disposed at right angles to the longitudinal axis of the bore 2.
  • the shaft 9 is part of, or may be connected to, the valve member of a rotary fluid-control valve (not shown).
  • a disc cam 10 is secured to the shaft 9 and has its peripheral surface bearing against the confronting surfaces of the pistons 6, 7.
  • the space 11 in the bore 2 between the end closure member 3 and the piston 6 and the space 12 between the end closure member 4 and the piston 7 form part of a press ⁇ urised fluid-supplying means for moving the piston assembly 5 in the bore 2.
  • the pressurised fluid-supplying means comprises a pressure intensifier, generally designated by the numeral 13, conn ⁇ ected to the spaces 11, 12 by piping described hereinafter in greater detail.
  • the pressure intensifier 13 comprises axially aligned cylinders 14 and 15 having bores of diameters d and D, respectively, d being smaller than D.
  • Non-return valves 31 and 32 are provided in the pipes 27 and 28, respectively, these valves allowing the flow of fluid into the cylinder 14 in the direction from the valve 23, but not in the opposite direction.
  • the valve 23 is a change-over valve which can be adjusted into either one of first and second limit posi ⁇ tions. In its first limit position, shown in Figure 1, the valve 23 connects the pipe 22 to the pipe 24 and conn- ects the pipe 29 to the pipe 30. In its second limit position, the valve 23 connects the pipe 22 to the pipe 30 and connects the pipe 29 to the pipe 24.
  • the cylinder 14, the cylinder spaces 11 and 12 and the pipes 20-22, 24 and 27-30 are all filled with hydraulic fluid.
  • the space 31 between the pistons 6 and 7 serves as a reservoir of hydraulic fluid and is connected by a pipe 32 to the pipe 29.
  • the space 31 is vented to atmos ⁇ phere at 33.
  • the cylinder 15 has its opposite ends connected to pipes 34 and 35, respectively, which are connected, via a changeover valve 36, similar to the valve 23, to a reser ⁇ voir 37 of compressed air and to exhaust 38.
  • the valve actuator shown in Figure 1 employs different pressurised media in the cylinders 14 and 15. If the wall 19 between the cylinders 14 and 15 is omitted, it is possible + * o use the same pressurised medium in both the cylinders 14 and 15. In this case, however, pressur ⁇ ised fluid at the pressure P will only be delivered to the cylinder space 11 (or 12) during upward movements (as viewed in Figure 1) of the piston 16 in the cylinder 14. During downward movements of the piston 16 only the pressure £ will arise in the cylinder space 42. This means, that it would take twice as long to turn the valve actuating shaft 9 through a given angle, compared with the embodiment shown in Figure 1.
  • Figures 2 and 3 show modified embodiments of the actuator of Figure 1 which employ the same pressure intensifier as the actuator of Figure 1.
  • the pressure intensifiers have been omitted from Figures 2 and 3, but it can be assumed that the parts shown in Figure 1 below the chain line A - A are also present in each of the embodiments of Figures 2 and 3 below the chain lines A - A in each of those Figures.
  • the valve actuator shown in Figure 2 again comprises a housing 1 with a cylindrical bore 2 and end closure members 3 and 4, a piston assembly 5 with spaced-apart pistons 6, 7 connected together by rods 8, a valve actuat ⁇ ing shaft 9 and a disc cam 10, all as described with refer ⁇ ence to Figure 1.
  • the numeral 50 designates a hollow cylindrical casing secured to the end closure member 4, the longitudinal axis of the casing 50 being aligned with the longitudinal axis of the bore 2.
  • a piston 51 is slidable in the casing 50 and a helical spring 52 is housed in the casing 50 between the end 53 of the casing and the piston 51.
  • a rod 54 which is slidable in fluid-tight manner in the end closure member 4, has one end connected to _the piston 51 and its other end abutting the piston 7.
  • the space 57 in the casing 50, between the piston 51 and the end 53 of the casing, is vented to atmosphere via a hole 58 in the end 53.
  • the change-over valve 23 again has two limit posi ⁇ tions. In the first limit position, shown in Figure 2, the valve connects the pipe 22 to the pipe 24. In its second limit position, the valve 23 connects the pipe 29 to the pipe 24.
  • hydraulic fluid at pressure P from the pressure intensifier 13 (see Figure 1) is delivered via pipes 22 and 24 to the spaee 11 in the bore 2 and to the space 55 in the casing 50.
  • the pressure intensifier 13 draws hydraulic fluid from the space 31 in the bore 2 via pipe 32.
  • the action of the pressure intensifier 13 results in movement of the piston assembly 5 to the right, as viewed in Figure 2, and clockwise rotation of the valve actuating shaft 9.
  • the hydraulic fluid supplied to the space 55 in the casing 50 moves the piston 51 to the right, as viewed in Figure 2, compressing the spring 52 and relieving the piston assembly 5 from the action of the spring 52.
  • FIG. 1 and 2 are rotary actuators.
  • Figure 3 shows a linear actuator comprising a housing 1, with a cylindrical bore 2 and end closure , members 3 and 4, in which a piston 60 is slidable.
  • the piston 60 has a piston rod 61 which passes through the end closure member 3 and forms part of, or is connected to, the linearly movable valve member of a fluid control valve (not shown), for example a gate valve.
  • a helical spring 62 is located in the housing 1 between the piston 60 and the end closure member 4.
  • the space 11 in the bore 2 is connected to the valve 23 by the pipe 24 and the space 63 in the bore 2, between the piston 60 and the end closure member 4, is connected to the pipe 32.
  • the change-over valve 23 is constructed in the same way as the change-over valve 23 of Figure 2.
  • hydraulic fluid at pressure P from the pressure intensifier 13 (see Figure 1) is delivered via pipes 22 and 24 to the space 11 in the bore 2.
  • the pressure intensifier 13 draws hydraulic fluid from the space 63 in the bore 2 via pipe 32.
  • the action of the pressure intensifier 13 results in movement of the piston 60 to the right, as viewed in Figure 3, and consequent mover.ent to the right of the valve actuating rod 61.
  • the spring 62 is compressed. If the change-over valve 23 is now moved to its previously mentioned second limit position, the pipe 24 is connected to the pipe 29, so that the space 11 becomes connected to the space 63 in the bore 2 via the pipes 24, 29 and 32.
  • the spring 62 then re-asserts itself and moves the piston 60 to the left (as viewed in Figure 3). This results in movement to the left of the valve actuating rod 61.
  • the invention is not, of course, limited to the par- ticular construction of the pressure intensifier 13 shown in Figure 1.
  • reciprocation of the piston for example, reciprocation of the piston

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Actuator (AREA)

Abstract

Un dispositif d'actionnement de vanne rotatif ou lineaire comprend un cylindre (1), un piston (6, 7) mobile dans un cylindre (1), un organe d'actionnement de vanne (9) actionne par le piston (6, 7) et des moyens d'alimentation en fluide sous pression, par exemple un fluide hydraulique, du cylindre (1) pour deplacer le piston (6, 7) dans le cylindre. Les moyens d'alimentation en fluide sous pression comprennent un dispositif d'intensification de pression (13) entraine par un milieu sous pression, par exemple de l'air comprime a une premiere pression et concus pour envoyer ce fluide sous pression au cylindre (1) du dispositif d'actionnement a une pression superieure a celle du milieu sous pression. Le dispositif d'intensification de pression (13) comprend de maniere appropriee un premier assemblage a piston et cylindre a double effet ayant un premier piston (7) qui est connecte mecaniquement a un second piston (16) d'un second assemblage a piston cylindre a double effet, le second piston (16) ayant une section plus petite que la section du premier piston (17) et les cylindres (15, 14) des deux assemblages a piston et cylindre ont leurs axes alignes, et des moyens (34-38) pour l'alimentation en milieu sous pression a cette premiere pression du premier assemblage a piston et cylindre dans le but d'animer d'un mouvement alternatif le premier piston (17) dans son cylindre (15). Le second assemblage a piston et cylindre constitue alors les moyens d'alimentation en fluide sous pression a la pression plus elevee du cylindre d'actionnement (1).A rotary or linear valve actuator comprises a cylinder (1), a piston (6, 7) movable in a cylinder (1), a valve actuator (9) actuated by the piston (6, 7 ) and means for supplying pressurized fluid, for example hydraulic fluid, to the cylinder (1) to move the piston (6, 7) in the cylinder. The means for supplying pressurized fluid comprise a pressure intensification device (13) driven by a pressurized medium, for example air compressed at a first pressure and designed to send this pressurized fluid to the cylinder (1 ) of the actuating device at a pressure higher than that of the medium under pressure. The pressure intensifier (13) suitably comprises a first double-acting piston and cylinder assembly having a first piston (7) which is mechanically connected to a second piston (16) of a second cylinder piston assembly double acting, the second piston (16) having a smaller section than the section of the first piston (17) and the cylinders (15, 14) of the two piston and cylinder assemblies have their aligned axes, and means (34- 38) for the supply of pressurized medium at this first pressure of the first piston and cylinder assembly in order to animate the first piston (17) in its cylinder (15) with an alternating movement. The second piston and cylinder assembly then constitutes the means for supplying pressurized fluid at the higher pressure of the actuating cylinder (1).

Description

- 1 -
Valve actuator
Technical Field
This invention relates to a valve actuator of the kind comprising a pressurised fluid-operated piston and cylinder assembly in which the piston is arranged to actu- ate the valve member of a valve. Although primarily intended for the actuation of rotary fluid-control valves, the actuator in accordance with the invention may be employed to actuate linearly actuable valves, for example gate valves.
Background Art
It is known (see Published European Application No. 0 034 882) to actuate a rotary fluid-control valve by means of a pressure fluid-operated actuator of the kind comprising a housing with a cylindrical bore, a piston assembly comprising a pair of spaced-apart pistons coupled together for simultaneous sliding movement within said cylindrical bore, a cam situated between the two pistons and secured to a valve actuating shaft rotatable about an axis fixed relative to the housing and disposed substan- tially at right angles to the longitudinal axis of said cylindrical bore with the peripheral surface of the cam engaging the confronting surfaces of the two pistons of said piston assembly, and means for supplying pressurised fluid to a space in said cylindrical bore for moving said piston assembly within the cylindrical bore.
By supplying a pressurised fluid, usually compressed air, to said space, the resulting movement of the piston assembly is converted by said cam into a rotary movement of said valve actuating shaft. The actuator may be of the single-acting type, in which rotation of the valve actuating shaft in only one direction, for example in the opening direction of the valve, can be effected by supplying pressurised fluid to said space, spring means then being provided for effecting rotation of the valve actuating shaft in the opposite direction. Alternatively, the actuator may be of the double-acting type, so' that rotation of the valve actuating shaft in either direction can be effected by supplying pressurised fluid to different spaces in said cylindrical bore. Also in this case, spring means may be provided to assist rotation of the shaft in the closing direction of the valve, so that the valve can be closed in the event of failure of the pressurised fluid supply.
It is also known to actuate a linearly operable fluid- control valve by an actuator in the form of a single- or double-acting piston and cylinder assembly, in which the linear movement of the piston rod of the actuator actuates the linearly movable valve member of the valve. This type of actuator may also comprise spring means for effecting or assisting movement of the piston, usually in the valve closing direction.
These rotary and linear valve actuators are usually operated by a pressurised fluid supply (generally compress- ed air) at a pressure of up to about 10 kg/cm (gauge). When moderately low valve actuating torques or thrusts are involved, for example torques of up to 1000 Nm or thrusts of up to 500 kg, the actuator does not have an unacceptably large size. However, there is an ever- increasing demand for valve actuators capable of producing considerably higher torques or thrusts than those quoted above, especially for operating valves on oil rigs. These higher torques or thrusts can, of course, be obtained by increasing the working pressure of the pressurised fluid without substantially increasing the overall dimen- sions of the actuator, but this leads to the disadvantage of having to provide very much more expensive auxiliary equipment for producing and storing the pressurised fluid at the considerably higher working pressure.
The present invention aims to provide a valve actuator of the kind referred to which does not have the disadvan¬ tage just referred to.
Disclosure of the Invention
According to the invention, a valve actuator compris- ing an actuator cylinder, an actuator piston movable in the cylinder, a valve actuating member actuable by said piston, and means for supplying pressurised fluid to said cylinder for moving said piston in said cylinder, is characterised in that said pressurised fluid-supplying means comprises a pressure intensifier driven by a pressur¬ ised medium at a first pressure and arranged to deliver said pressurised fluid to said actuator cylinder at a pressure higher than that of said pressurised medium.
Said pressure intensifier may comprise first and second piston and cylinder assemblies having their cylin¬ ders axially aligned with one another* and their pistons mechanically connected, ' the piston of said first piston and cylinder assembly having a larger area than the piston of said second piston and cylinder assembly, and means for supplying said pressurised medium at said first pres¬ sure to said first piston and cylinder assembly, said second piston and cylinder assembly constituting the means for supplying pressurised fluid at said higher pressure to said actuator cylinder. Said first piston and cylinder assembly may be double-acting, so that the piston of said first piston and cylinder assembly may be reciprocated in its cylinder by said pressurised medium. Then, by connecting the cylinder of said second piston and cylinder assembly to said actuator cylinder via a system of non- return valves, reciprocation of the piston of said second piston and cylinder assembly can be made to cause movement of said actuator piston in one direction in said actuator cylinder.
In one embodiment of a valve actuator in accordance with the invention, said pressure intensifier comprises a first double-acting piston and cylinder assembly having a piston of a first diameter D which is mechanically conn¬ ected to the piston of a second double-acting piston and cylinder assembly having a piston of a second diameter d which is smaller than D, the cylinders of the two assem¬ blies having their axes aligned with one another. The piston of the first assembly is reciprocated in its cylin¬ der by supplying a pressurised fluid medium, for example compressed air, to its cylinder at a pressure p_, which is the aforesaid first pressure. The pressure £ may, for example, be in the range of from 4 to 10 kg/cm (gauge). This reciprocation of the piston of the first assembly results in reciprocation of the piston of the second assem- bly and the creation of a pressure P in the fluid in the aforesaid pressurised fluid-supplying means, the pressure P, which is the aforesaid second pressure, being higher than the pressure £ in accordance with the equation:
P _ p. ≤ _!
Thus, for example, by giving the piston of the first assem¬ bly a diameter D which is equal to 5cl, the pressure P created in said pressurised fluid-supplying means will be 25£. Therefore, for example, if the first piston and cylinder assembly is actuated with compressed air at a
2 pressure of 8 kg/cm (gauge), it is possible to create
2 a pressure of 200 kg/cm (gauge) in said pressurised fluid- supplying means.
In the embodiment just described, the pressurised fluid at the pressure P is contained in a closed, or sub- stantially closed, circuit which includes the second piston and cylinder assembly of the pressure intensifier and the actuator cylinder of the valve actuator. In this case the pressurised fluid at the pressure P may be a fluid of the same or a different nature from the pressur- ised -medium at the pressure £. At present, we prefer to employ a hydraulic fluid for the fluid at the pressure P and compressed air for the medium at the pressure £. If, however, in the above described embodiment, the second piston and cylinder assembly is single-acting instead of double-acting, it is possible to use one and the same pressurised fluid in both of the piston and cylinder assem¬ blies of the pressure intensifier.
A single pressure intensifier may be common to a plurality of valve actuators, the actuator cylinders of the various actuators then being connected in parallel with the pressure intensifier.
Brief Description of the Drawings
The invention will now be described; by way of example, with reference to the accompanying drawings, in which
Figure 1 is a schematic sectional view of a first embodiment of a valve actuator in accordance with the ■invention, 'and
Figures 2 and 3 are schematic sectional views of parts of two modified forms of the embodiment of Figure 1.
Best Mode of Carrying Out the Invention
The valve actuator shown in Figure 1 comprises a housing 1 having a circular cylindrical bore 2 therein and end closure members 3 and 4. Slidable within the bore 2 is a piston assembly, generally designated by the reference numeral 5, which comprises two pistons 6, 7 held together in spaced-apart relationship by rods 8.
A valve actuating shaft 9 is rotatably mounted in the wall of the housing 1, the axis of the shaft being disposed at right angles to the longitudinal axis of the bore 2. The shaft 9 is part of, or may be connected to, the valve member of a rotary fluid-control valve (not shown). A disc cam 10 is secured to the shaft 9 and has its peripheral surface bearing against the confronting surfaces of the pistons 6, 7.
The space 11 in the bore 2 between the end closure member 3 and the piston 6 and the space 12 between the end closure member 4 and the piston 7 form part of a press¬ urised fluid-supplying means for moving the piston assembly 5 in the bore 2. In addition to the spaces 11 and 12, the pressurised fluid-supplying means comprises a pressure intensifier, generally designated by the numeral 13, conn¬ ected to the spaces 11, 12 by piping described hereinafter in greater detail.
The pressure intensifier 13 comprises axially aligned cylinders 14 and 15 having bores of diameters d and D, respectively, d being smaller than D. Pistons 16 and
17 are slidable in the cylinders 14 and 15, respectively, and the two pistons are joined to one another by a rod
18 which is slidable, in a fluid-tight manner in a wall 19 between the two cylinders 14, 15. Opposite ends of the cylinder 14 are connected by pipes 20 and 21, respec¬ tively, to a pipe 22 which is connected to a valve 23. A pipe 24 leads from the valve 23 to the space 11. in the bore 2. Non-return valves 25 and 26 are provided in the pipes 20 and 21, respectively, these valves allowing the flow of fluid from the cylinder 14 in the direction towards the valve 23, but not in the opposite direction. Opposite ends of the cylinder 14 are also connected by pipes 27 and 28, respectively, to a pipe 29 which is connected to the valve 23. A further pipe 30 connects the valve 23 to the space 12 in the bore 2. Non-return valves 31 and 32 are provided in the pipes 27 and 28, respectively, these valves allowing the flow of fluid into the cylinder 14 in the direction from the valve 23, but not in the opposite direction. The valve 23 is a change-over valve which can be adjusted into either one of first and second limit posi¬ tions. In its first limit position, shown in Figure 1, the valve 23 connects the pipe 22 to the pipe 24 and conn- ects the pipe 29 to the pipe 30. In its second limit position, the valve 23 connects the pipe 22 to the pipe 30 and connects the pipe 29 to the pipe 24.
The cylinder 14, the cylinder spaces 11 and 12 and the pipes 20-22, 24 and 27-30 are all filled with hydraulic fluid. The space 31 between the pistons 6 and 7 .serves as a reservoir of hydraulic fluid and is connected by a pipe 32 to the pipe 29. The space 31 is vented to atmos¬ phere at 33.
The cylinder 15 has its opposite ends connected to pipes 34 and 35, respectively, which are connected, via a changeover valve 36, similar to the valve 23, to a reser¬ voir 37 of compressed air and to exhaust 38.
Let is be assumed that the various items described above are in their respective positions shown in Figure 1. Under these conditions, compressed air at a pressure £ in the reservoir 37 flows to the cylinder space 39 in the cylinder 15 and the cylinder space 40 is connected to exhaust 38. The piston 17 therefore rises in the cylin¬ der 15 and forces the piston 16 to rise in the cylinder 14. Hydraulic fluid in the cylinder space 41 above the piston 16 is forced out via pipes 20, 22 and 24 into the cylinder space 11 and moves the piston assembly 5 to the right in the bore 2, as viewed in Figure 1. Hydraulic fluid in the cylinder space 12 is forced out of this space via the pipes 30, 29 and 28 into the cylinder space 42 below the piston 16. The pressure P in the hydraulic fluid delivered to the cylinder space 11 is considerably higher than the pressure £ of the compressed air in the reservoir 37, as determined by the equation P = £. ~2 d'
Movement of the piston assembly 5 to the right, as described above, causes rotation of the cam 10, and hence rotation of the valve actuating shaft 9 in a clockwise direction, as viewed in Figure 1.
When the piston 17 reaches the upper end of its stroke in the cylinder 15, the change-over valve 36 is moved to its other limit position, so that the cylinder space 40 is .connected to the reservoir 37 and the cylinder space 39 is connected to exhaust 38. The piston 17 then moves downwardly in the cylinder 15 and forces the piston 16 to move downwardly in the cylinder 14. Hydraulic fluid in the cylinder space 42 below the piston 16 is then.forced out via pipes 21, 22 and 24 into the cylinder space 11 and again moves the piston assembly 5 to the right in the bore 2. Hydraulic fluid in the cylinder space 12 is forced out of this space via the pipes 30, 29 and 27 into the cylinder space 41 above the piston 16.
From the above description it will be appreciated that, by reciprocating the piston 17 in the cylinder 15, which is effected by moving the change-over valve 36 between its two limit positions, the piston assembly 5 can be moved to .the right to turn the valve actuating shaft in a clockwise direction.
By moving the change-over valve 23 to its other limit position, in which the pipes 22 and 30 are connected to one another and the pipes 24 and 29 are connected to one another, reciprocation of the piston 17 in the cylinder 15 results in movement of the piston assembly 5 to the left, as viewed in Figure 1, and consequent anticlockwise rotation of the valve actuating shaft 9.
In the event of failure of the compressed air supply to the cylinder 15, manual reciprocation of the pistonj 16 and 17 may be effected using a lever arm 43 pivotally connected to a rod 44 connected to the piston 16 and pass¬ ing out of the upper end of the cylinder 14.
The valve actuator shown in Figure 1 employs different pressurised media in the cylinders 14 and 15. If the wall 19 between the cylinders 14 and 15 is omitted, it is possible +*o use the same pressurised medium in both the cylinders 14 and 15. In this case, however, pressur¬ ised fluid at the pressure P will only be delivered to the cylinder space 11 (or 12) during upward movements (as viewed in Figure 1) of the piston 16 in the cylinder 14. During downward movements of the piston 16 only the pressure £ will arise in the cylinder space 42. This means, that it would take twice as long to turn the valve actuating shaft 9 through a given angle, compared with the embodiment shown in Figure 1.
Figures 2 and 3 show modified embodiments of the actuator of Figure 1 which employ the same pressure intensifier as the actuator of Figure 1. To simplify the drawings, the pressure intensifiers have been omitted from Figures 2 and 3, but it can be assumed that the parts shown in Figure 1 below the chain line A - A are also present in each of the embodiments of Figures 2 and 3 below the chain lines A - A in each of those Figures.
Parts in Figures 2 and 3 which are the same as, or similar to, parts in Figure 1 have been designated with the same reference numerals as in Figure 1.
The valve actuator shown in Figure 2 again comprises a housing 1 with a cylindrical bore 2 and end closure members 3 and 4, a piston assembly 5 with spaced-apart pistons 6, 7 connected together by rods 8, a valve actuat¬ ing shaft 9 and a disc cam 10, all as described with refer¬ ence to Figure 1. The numeral 50 designates a hollow cylindrical casing secured to the end closure member 4, the longitudinal axis of the casing 50 being aligned with the longitudinal axis of the bore 2. A piston 51 is slidable in the casing 50 and a helical spring 52 is housed in the casing 50 between the end 53 of the casing and the piston 51. A rod 54, which is slidable in fluid-tight manner in the end closure member 4, has one end connected to _the piston 51 and its other end abutting the piston 7. A space 55 in the casing 50, between the end closure member 4 and the .piston 51, is connected by a pipe 56 to the pipe 24 which connects the valve 23 to the space 11 in the bore 2. The space 57 in the casing 50, between the piston 51 and the end 53 of the casing, is vented to atmosphere via a hole 58 in the end 53.
The change-over valve 23 again has two limit posi¬ tions. In the first limit position, shown in Figure 2, the valve connects the pipe 22 to the pipe 24. In its second limit position, the valve 23 connects the pipe 29 to the pipe 24.
In use of the actuator shown in Figure 2, hydraulic fluid at pressure P from the pressure intensifier 13 (see Figure 1) is delivered via pipes 22 and 24 to the spaee 11 in the bore 2 and to the space 55 in the casing 50. At this time, the pressure intensifier 13 draws hydraulic fluid from the space 31 in the bore 2 via pipe 32. The action of the pressure intensifier 13 results in movement of the piston assembly 5 to the right, as viewed in Figure 2, and clockwise rotation of the valve actuating shaft 9. At the same time, the hydraulic fluid supplied to the space 55 in the casing 50 moves the piston 51 to the right, as viewed in Figure 2, compressing the spring 52 and relieving the piston assembly 5 from the action of the spring 52. Consequently, a substantially constant torque is applied to the valve actuating shaft 9 as the piston assembly 5 moves to the right along the bore 2. If the change-over valve 23 is now moved to its prev¬ iously mentioned second limit position, the pipe 24 is connected to the pipe 29, so that the spaces 11 and 55 become connected to the space 31 in the bore 2 via the pipes 24, 29 and 32. The spring 52 then re-asserts itself and moves the piston assembly 5 to the left (as viewed in Figure 2) via the piston 51 and the rod 54. This results in rotation of the valve actuating shaft 9 in the anticlockwise direction.
The valve actuators of Figures 1 and 2 are rotary actuators. Figure 3 shows a linear actuator comprising a housing 1, with a cylindrical bore 2 and end closure, members 3 and 4, in which a piston 60 is slidable. The piston 60 has a piston rod 61 which passes through the end closure member 3 and forms part of, or is connected to, the linearly movable valve member of a fluid control valve (not shown), for example a gate valve.
A helical spring 62 is located in the housing 1 between the piston 60 and the end closure member 4. The space 11 in the bore 2 is connected to the valve 23 by the pipe 24 and the space 63 in the bore 2, between the piston 60 and the end closure member 4, is connected to the pipe 32. The change-over valve 23 is constructed in the same way as the change-over valve 23 of Figure 2.
In use of the actuator shown in Figure 3, hydraulic fluid at pressure P from the pressure intensifier 13 (see Figure 1) is delivered via pipes 22 and 24 to the space 11 in the bore 2. At this time the pressure intensifier 13 draws hydraulic fluid from the space 63 in the bore 2 via pipe 32. The action of the pressure intensifier 13 results in movement of the piston 60 to the right, as viewed in Figure 3, and consequent mover.ent to the right of the valve actuating rod 61. At the same time, the spring 62 is compressed. If the change-over valve 23 is now moved to its previously mentioned second limit position, the pipe 24 is connected to the pipe 29, so that the space 11 becomes connected to the space 63 in the bore 2 via the pipes 24, 29 and 32. The spring 62 then re-asserts itself and moves the piston 60 to the left (as viewed in Figure 3). This results in movement to the left of the valve actuating rod 61.
The invention is not, of course, limited to the par- ticular construction of the pressure intensifier 13 shown in Figure 1. For example, reciprocation of the piston
17 in the cylinder 15 may be effected with a pressurised medium in other ways than that described.
Again, it must also be appreciated that the drawings are of a purely schematic nature and that in practice the parts 1, 1.3 and 23 would not necessarily be separate from one another, but could be assembled together in a single unit.

Claims

1. A valve actuator comprising an actuator cylinder (1), an actuator piston (6, 7; 60) movable in the cylinder (1), a valve actuating member (9; 61) actuable by said piston (6, 7; 60) and means for supplying pressurised fluid to said cylinder (1) for moving said piston (6, 7;60) in said cylinder (1), characterised in that said pressur¬ ised fluid-supplying means comprises a pressure intensifier (13) driven by a pressurised medium at a first pressure and arranged to deliver said pressurised fluid to said actuator cylinder (l) at a pressure higher than that of said pressurised medium.
2. A valve actuator according to claim 1, in which said pressure intensifier (13) comprises first and second piston and cylinder assemblies having their cylinders (15, 14) axially aligned with one another and their pistons (17, 16) mechanically connected, the piston (17) of said first piston and cylinder assembly having a larger area than the piston (16) of said second piston and cylinder assembly, and means (34-38) for supplying said pressurised medium at said first pressure to said first piston and cylinder assembly, said second piston and cylinder assembly constituting the means for supplying pressurised fluid at said higher pressure to said actuator cylinder (1).
3. A valve actuator according to claim 2, in which said first piston and cylinder assembly is double-acting, whereby the piston (17) of said first piston and cylinder assembly may be reciprocated in its cylinder (15) by said pressurised medium.
4. A valve actuator according to claim 3, in which the cylinder (14) of said second piston and cylinder assem¬ bly is connected to said actuator cylinder (1) via a system of non-return valves (25, 26, 31, 32) whereby reciprocation of the piston (16) of said second piston and cylinder assembly causes movement of said actuator piston (6, 7;60) in one direction in said actuator cylinder (1).
5. A valve actuator according to any of the preceding claims, in which said actuator piston (6, 7) and actuator cylinder (1) provide a double-acting assembly.
6. A valve actuator according to any of claims 1 to 4, in which said actuator piston (60) and actuator cylinder (1) provide a single-acting assembly in which said pressurised fluid is employed to drive said actuator piston (60) in one direction and spring means (62) is arranged to drive said actuator piston (60) in the opposite direction.
7. A valve actuator according to any of the preced¬ ing claims, in which said valve actuating member (9) is rotatable by said actuator piston (6, 7).
8. A valve actuator according to any of claims 1 to 6, in which said valve actuating member (51) is linearly movable by said actuator piston (60).
EP19820900213 1981-01-12 1982-01-11 Valve actuator Withdrawn EP0069128A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8100799 1981-01-12
GB8100799 1981-01-12

Publications (1)

Publication Number Publication Date
EP0069128A1 true EP0069128A1 (en) 1983-01-12

Family

ID=10518926

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19820900213 Withdrawn EP0069128A1 (en) 1981-01-12 1982-01-11 Valve actuator

Country Status (3)

Country Link
EP (1) EP0069128A1 (en)
AU (1) AU7939982A (en)
WO (1) WO1982002423A1 (en)

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Publication number Priority date Publication date Assignee Title
WO1992008375A1 (en) * 1990-11-19 1992-05-29 Real Foods Pty. Ltd. Cooking machine
NO940447D0 (en) * 1994-02-10 1994-02-10 Abb Teknologi As Electric drive means
DE102004061298A1 (en) * 2004-12-20 2006-06-22 Bosch Rexroth Aktiengesellschaft linear actuator
DE102010063487A1 (en) * 2010-12-20 2012-06-21 Zf Friedrichshafen Ag Device for actuating a working cylinder
EP3470687A1 (en) * 2017-10-12 2019-04-17 Nova Werke AG Pneumatic valve actuator

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GB939951A (en) * 1960-04-21 1963-10-16 Conrad Roy Bates Improvements relating to booster-assisted hydraulic systems
FR1269305A (en) * 1960-06-25 1961-08-11 Frank & Pignard Double-acting hydro-pneumatic control device with automatic recovery and compensation of hydraulic volumes
US3405522A (en) * 1964-11-25 1968-10-15 Toyoda Machine Works Ltd Hydraulic motor control circuit
US3570101A (en) * 1968-07-01 1971-03-16 Skyhi Ltd Hydraulic and pneumatic system for controlling tools
FR2041511A5 (en) * 1969-04-28 1971-01-29 Viaud Jean
US4043533A (en) * 1975-08-14 1977-08-23 Atwood & Morrill Co. Auxiliary closing force for valves

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Title
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Also Published As

Publication number Publication date
AU7939982A (en) 1982-08-02
WO1982002423A1 (en) 1982-07-22

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