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GB1594269A - Control valves - Google Patents

Control valves Download PDF

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Publication number
GB1594269A
GB1594269A GB1705680A GB1705680A GB1594269A GB 1594269 A GB1594269 A GB 1594269A GB 1705680 A GB1705680 A GB 1705680A GB 1705680 A GB1705680 A GB 1705680A GB 1594269 A GB1594269 A GB 1594269A
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GB
United Kingdom
Prior art keywords
valve
fluid
pressure
flow
inlet
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.)
Expired
Application number
GB1705680A
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.)
Shoketsu Kinzoku Kogyo KK
Original Assignee
Shoketsu Kinzoku Kogyo KK
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 Shoketsu Kinzoku Kogyo KK filed Critical Shoketsu Kinzoku Kogyo KK
Publication of GB1594269A publication Critical patent/GB1594269A/en
Expired 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/01—Locking-valves or other detent i.e. load-holding devices
    • 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
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • 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
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
    • 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40576—Assemblies of multiple valves
    • F15B2211/40584—Assemblies of multiple valves the flow control means arranged in parallel with a check valve
    • 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
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41527—Flow control characterised by the connections of the flow control means in the circuit being connected to an output member and a directional control valve
    • 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
    • F15B2211/40—Flow control
    • F15B2211/46—Control of flow in the return line, i.e. meter-out 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
    • F15B2211/40—Flow control
    • F15B2211/47—Flow control in one direction only
    • F15B2211/473—Flow control in one direction only without restriction in the reverse direction
    • 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
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50554—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure downstream of the pressure control means, e.g. pressure reducing valve
    • 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
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
    • 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
    • F15B2211/50—Pressure control
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/528—Pressure control characterised by the type of actuation actuated by fluid pressure
    • 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
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Safety Valves (AREA)
  • Details Of Valves (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Check Valves (AREA)

Description

(54) IMPROVEMENTS IN OR RELATING TO CONTROL VALVES (71) We, SHOKETSU KINZOKU KOGYO KABUSHIKI KAISHA, a Japanese company, of 13 12, Shinbashi l-chome, Minato-ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to control valves for use in a fluid-pressure operating system and more particularly but not exclusively is concerned with a control valve which can be positioned between a flow direction-changeover valve and an actuator.A control valve according to the invention may prevent an impulsive operation of an actuator by slowing down the movement of a piston under a meter-in control, as, for example, at the start of an operation when there is no fluid pressure in the actuator, and yet may allow normal movement of a piston during the operation.
Hitherto, for adjusting the speed of a piston reciprocating within a cylinder in an actuator, a meter-out control system has been adopted for a speed controller. However, the meter-out control system has the disadvantage that, for instance, after the operation, or during checking of the equipment, the pressure within the cylinder remains at an atmospheric pressure level which disables the speed control of the piston as the speed control of a piston is possible only when a pressure is applied to the controller. As a result, this often leads to damage of fixtures or the like or injury of an operator. Accordingly, an operator needs to pay close attention to the operation at the beginning thereof, so that the efficiency of the operation may be lowered.
For the aforesaid reasons, the speed controller is used in a meter-in control mode.
Although this attempt is partially successful in preventing the impulsive movement of the piston at the start of operation, it suffers from the disadvantage that it takes an excessively long time for the fluid pressure within the cylinder to build up, and hence the speed of the piston is lowered, so that there arises a delay in transmission of a pressure, with an accompanying loss in operating efficiency.
Our copending application No. 35581/77 (Specification No. 1594268) inter alia describes in greater detail several conventional fluid circuits, particular with reference to Figures IA, 1B and 1C of the drawings thereof.
According to the present invention there is provided a control valve comprising: a body provided with two ports serving as an inlet and an outlet for a fluid; first and second fluid passages provided in parallel in said body for interconnecting said two ports; a first valve disposed and arranged so as to act (i) as a check valve to prevent flow through the first fluid passage when the pressure at the inlet is higher than at the outlet, and (ii) as a throttle valve to control flow through the first fluid passage when the pressure at the inlet is lower than that at the outlet;; a second valve disposed and arranged so as to affect the flow in the second fluid passage, the second valve being operative when the pressure at the inlet is higher than that at the outlet, and acting as a throttle valve when the pressure differential between the inlet and the outlet is less than a predetermined level, and being fully open when open when the said pressure differential is above the predetermined level; and a third, check valve disposed to allow flow via the second fluid passage from the inlet to the outlet only.
The invention also provides a fluid circuit including a flow control valve in accordance with the invention.
Generally, the first valve will be such that its permissible degree of opening is adjusta ble, preferably from outside the valve body.
Preferably, the first valve includes a valve stem which is loosely fitted into a valve member, the relative movement possible between the valve stem and the valve member determining the maximum possible opening of said first valve. The second valve can comprise a valve member and a valve seat, biassing means urging the valve member towards the valve seat, and a by-pass channel formed in the valve member to allow a limited flow through the valve when the valve member is seated against the valve seat.
The biassing means of the second valve is advantageously adjustable, preferably from outside the valve body.
For a better understanding of the present invention and to show more clearly how the same may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a vertical cross-sectional view of a preferred embodiment of a control valve in accordance with the invention; Figure 2 is a circuit diagram including the control valve shown in Figure l; and Figure 3 is a circuit diagram including the control valve shown in Figure 1.
Referring to Figure 1 of the drawings. the body 301 of a control valve is provided with an inlet port 302 which in use can be connected to a flow direction-changeover valve, and an outlet port 303 which in use can be connected to a cylinder in an actuator.
Provided in parallel in the body 301 are two fluid passages 304, 305 interconnecting the two ports 302 and 303. A first valve 306 is provided in the first fluid passage 304, and serves as a check valve for a fluid flowing in the normal direction i.e., from the port 302 towards the port 303, and a throttle valve for flow in the opposite direction. The first valve 306 comprises a valve member 308 which is seated on a valve seat 307 provided in the passage 304 in the side near the port 302, and a valve stem 310 which is loosely fitted in a centre holde 309 defined in the valve member 308. The valve stem 310 protrudes outside the body of the control valve, and is hermetically sealed with an O-ring 311.The exterior end face of stem 310 is provided with an adjusting slot 312; and the valve stem 310 has a thread 315 which is fitted in a female thread formed in a seat member 313 secured to the body 301. The rotation of a screw driver, with its tip fitted in the slot 312, allows the rotation of the valve stem 310, thereby adjusting the maximum extent to which the valve member 308 can move away from the valve seat 307. In this case, the peripheral surface of valve member 308 is tapered, so that an opening or clearance between the valve member 308 and the valve seat 307 may be varied, continuously.
A second valve 317 is placed on the side of the port 302 in opposed relation to a valve seat 316 formed in the second fluid passage 305. The valve 317 allows the flow of fluid in the aforesaid normal direction, i.e. from the port 302 to port 303, acting as a throttle valve when the pressure differential between the inlet and the outlet is below a predetermined level, and being fully open when the pressure differential exceeds the set level. In addition, a check valve 318 is placed on the side of port 303 for blocking the flow of fluid from the port 303 towards valve 317 and the fluid passage 305, i.e. in the direction opposite to the aforesaid normal direction. The second valve 317 comprises a valve member 319 and a corresponding valve seat 316, and a pressure-adjusting spring 322, which is confined between a piston 320 and a pressure-adjusting member 321.In addition, a narrow passage 323 is provided in the valve member 319 for allowing communication between the port 302 and the port 303, thereby forming a fixed throttle valve when valve member 319 is seated against the valve seat 316. In addition, an adjusting slot 324 is provided in the exterior end face of the pressure-adjusting member 321 so as to allow adjustment, by a screwdriver. Fluid pressure on the side of port 302 (primary pressure) is applied to the piston 320 of the second valve 317. If the fluid pressure is lower than a pressure level set by the pressure adjusting spring 322, the fluid flows through the narrow passage 323, with the flow of a fluid being restricted.
When the fluid pressure exceeds the set pressure level, then the pressure adjusting spring 322 is compressed, so that the valve member 319 lifts up from the valve seat 316 to its fully open position, so a fluid may freely flow to the secondary side, i.e. towards the port 303. In this case, the valve member 325 of the check valve 318 downstream of the second valve 317 is seated on the valve seat 316 from the side of port 303 under the action of spring 326. The valve member 325 allows the flow of fluid from the second fluid passage 305 (e.g. via passage 323) towards the port 303, but blocks the flow of fluid in the opposite direction, i.e. from the port 303 into the passage 305. Flow from port 303 into passage 304 in unhindered by valve 308.
When the port 302 is connected to a flowdirection-changeover valve and port 303 is connected to a cylinder in an actuator, a fluid is introduced from the flow direction-changeover valve through the port 302 into the body 301. At this moment, the passage 304 is blocked by the first valve 306 functioning as a check valve, so that fluid flows through the passage 305 towards the second valve 317, through the narrow passage 323, and opens the valve member 325 to flow into the port 303, and then from there into the cylinder of the actuator.When fluid pressure in the actuator builds up to a value above a pressure level set by the aforesaid pressure adjusting spring 322, then the piston 320 compresses the pressure adjusting spring 322 so as to allow the valve member 319 to lift up from the valve seat 316, and to bring the valve 317 to its fully open position, thereby allowing a large amount of fluid to flow into the cylinder in the actuator. In other words, the amount of a fluid to be fed to the cylinder initially is small, so that abrupt or impulsive movement of the piston within the cylinder may be prevented.
When fluid flows in the direction opposite to the normal direction, i.e. from the port 303 to the port 302, fluid passes through the fluid passage 304. In this respect, the first valve 306 functions as a throttle valve, thereby adjusting the amount of a fluid flowing therethrough, commensurate with a clearance defined between the valve member 306 and the valve seat 307.
Referring to Figure 3, there is shown a fluid pressure source 327, a flow direction valve 328, a cylinder 329 of an actuator and a piston 330 in the cylinder. The control valve in accordance with the present invention is connected to the head-side chamber in the cylinder 329, while a speed controller 331 is connected to the rod-side chamber in the cylinder 329. Figure 3 shows a meter-out control mode, while preventing impulsive movement of a piston.
Our copending patent application No.
36410/77 (Serial No. 1591542) describes and claims a flow rate control valve comprising: a body provided with two ports serving as an inlet and an outlet for a fluid; a first fluid passage interconnecting said two ports; a first, pressure regulating valve disposed in said first fluid passage and which, in use, opens at inlet pressures exceeding a preset pressure level; means for adjusting, from outside the flow rate control valve, the force of a pressure adjusting spring, which loads said pressure regulating valve resiliently; a second fluid passage in parallel with said first fluid passage; a second, flow adjusting valve positioned in said second fluid passage and constructed so as to allow fluid flow in a direction from the outlet to the inlet when the pressure at the outlet exceeds that at the inlet; and means for adjusting, from outside the flow rate control valve, the maximum valve clearance provided by said second valve in said second fluid passage.
WHAT WE CLAIM IS: 1. A control valve comprising: a body provided with two ports serving as an inlet and an outlet for a fluid; first and second fluid passages provided in parallel in said body for interconnecting said two ports; a first valve disposed and arranged so as to act (i) as a check valve to prevent flow through the first fluid passage when the pressure at the inlet is higher than that at the outlet, and (ii) as a throttle valve to control flow through the first fluid passage when the pressure at the inlet is lower than that at the outlet;; a second valve disposed and arranged so as to affect the flow in the second fluid passage, the second valve being operative when the pressure at the inlet is higher than that at the outlet, and acting as a throttle valve when the pressure differential between the inlet and the outlet is less than a predetermined level, and being fully open when the said pressure differential is above the predetermined level; and a third, check valve disposed to allow flow via the second fluid passage from the inlet to the outlet only.
2. A valve as claimed in claim 1, wherein the permissible degree of opening of said first valve is adjustable.
3. A valve as claimed in claim 2, wherein the degree of opening of said first valve can be adjusted from outside the valve body.
4. A valve as claimed in claim 1, 2 or 3, wherein said first valve includes a valve stem which is loosely fitted into a valve member, the relative movement possible between the valve stem and the valve member determining the maximum possible opening of said first valve.
5. A valve as claimed in claim 1,2,3 or 4, wherein the second valve comprises a valve member and a valve seat, biassing means urging the valve member towards the valve seat, and a by-pass channel formed in the valve member to allow a limited flow through the valve when the valve member is seated against the valve seat.
6. A valve as claimed in claim 5, wherein said biassing means is adjustable.
7. A valve as claimed in claim 6, wherein said biassing means is adjustable from outside the valve body.
8. A control valve substantially as here it before described with reference to, and as illustrated in, the accompanying drawings.
9. A fluid circuit including a control valve as claimed in any preceding claim.
10. A fluid circuit substantially as hereinbefore described with reference to, and as illustrated in, Figure 3 of the accompanying drawings.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    pressure level set by the aforesaid pressure adjusting spring 322, then the piston 320 compresses the pressure adjusting spring 322 so as to allow the valve member 319 to lift up from the valve seat 316, and to bring the valve 317 to its fully open position, thereby allowing a large amount of fluid to flow into the cylinder in the actuator. In other words, the amount of a fluid to be fed to the cylinder initially is small, so that abrupt or impulsive movement of the piston within the cylinder may be prevented.
    When fluid flows in the direction opposite to the normal direction, i.e. from the port 303 to the port 302, fluid passes through the fluid passage 304. In this respect, the first valve 306 functions as a throttle valve, thereby adjusting the amount of a fluid flowing therethrough, commensurate with a clearance defined between the valve member 306 and the valve seat 307.
    Referring to Figure 3, there is shown a fluid pressure source 327, a flow direction valve 328, a cylinder 329 of an actuator and a piston 330 in the cylinder. The control valve in accordance with the present invention is connected to the head-side chamber in the cylinder 329, while a speed controller 331 is connected to the rod-side chamber in the cylinder 329. Figure 3 shows a meter-out control mode, while preventing impulsive movement of a piston.
    Our copending patent application No.
    36410/77 (Serial No. 1591542) describes and claims a flow rate control valve comprising: a body provided with two ports serving as an inlet and an outlet for a fluid; a first fluid passage interconnecting said two ports; a first, pressure regulating valve disposed in said first fluid passage and which, in use, opens at inlet pressures exceeding a preset pressure level; means for adjusting, from outside the flow rate control valve, the force of a pressure adjusting spring, which loads said pressure regulating valve resiliently; a second fluid passage in parallel with said first fluid passage; a second, flow adjusting valve positioned in said second fluid passage and constructed so as to allow fluid flow in a direction from the outlet to the inlet when the pressure at the outlet exceeds that at the inlet; and means for adjusting, from outside the flow rate control valve, the maximum valve clearance provided by said second valve in said second fluid passage.
    WHAT WE CLAIM IS: 1. A control valve comprising: a body provided with two ports serving as an inlet and an outlet for a fluid; first and second fluid passages provided in parallel in said body for interconnecting said two ports; a first valve disposed and arranged so as to act (i) as a check valve to prevent flow through the first fluid passage when the pressure at the inlet is higher than that at the outlet, and (ii) as a throttle valve to control flow through the first fluid passage when the pressure at the inlet is lower than that at the outlet;; a second valve disposed and arranged so as to affect the flow in the second fluid passage, the second valve being operative when the pressure at the inlet is higher than that at the outlet, and acting as a throttle valve when the pressure differential between the inlet and the outlet is less than a predetermined level, and being fully open when the said pressure differential is above the predetermined level; and a third, check valve disposed to allow flow via the second fluid passage from the inlet to the outlet only.
  2. 2. A valve as claimed in claim 1, wherein the permissible degree of opening of said first valve is adjustable.
  3. 3. A valve as claimed in claim 2, wherein the degree of opening of said first valve can be adjusted from outside the valve body.
  4. 4. A valve as claimed in claim 1, 2 or 3, wherein said first valve includes a valve stem which is loosely fitted into a valve member, the relative movement possible between the valve stem and the valve member determining the maximum possible opening of said first valve.
  5. 5. A valve as claimed in claim 1,2,3 or 4, wherein the second valve comprises a valve member and a valve seat, biassing means urging the valve member towards the valve seat, and a by-pass channel formed in the valve member to allow a limited flow through the valve when the valve member is seated against the valve seat.
  6. 6. A valve as claimed in claim 5, wherein said biassing means is adjustable.
  7. 7. A valve as claimed in claim 6, wherein said biassing means is adjustable from outside the valve body.
  8. 8. A control valve substantially as here it before described with reference to, and as illustrated in, the accompanying drawings.
  9. 9. A fluid circuit including a control valve as claimed in any preceding claim.
  10. 10. A fluid circuit substantially as hereinbefore described with reference to, and as illustrated in, Figure 3 of the accompanying drawings.
GB1705680A 1977-07-05 1977-10-27 Control valves Expired GB1594269A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP8816877U JPS6120362Y2 (en) 1977-07-05 1977-07-05

Publications (1)

Publication Number Publication Date
GB1594269A true GB1594269A (en) 1981-07-30

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ID=13935378

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1705680A Expired GB1594269A (en) 1977-07-05 1977-10-27 Control valves

Country Status (2)

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JP (1) JPS6120362Y2 (en)
GB (1) GB1594269A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2514574C1 (en) * 2013-03-19 2014-04-27 Андрей Юрьевич Беляев Safety valve unit

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020085183A (en) * 2018-11-29 2020-06-04 Smc株式会社 Hydraulic cylinder drive

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2514574C1 (en) * 2013-03-19 2014-04-27 Андрей Юрьевич Беляев Safety valve unit

Also Published As

Publication number Publication date
JPS6120362Y2 (en) 1986-06-19
JPS5417130U (en) 1979-02-03

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Legal Events

Date Code Title Description
PS Patent sealed
PE20 Patent expired after termination of 20 years

Effective date: 19971026