GB2242256A

GB2242256A - Valve for fluid

Info

Publication number: GB2242256A
Application number: GB9103904A
Authority: GB
Inventors: John Andrew Timmins; John Timmins
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-02-27
Filing date: 1991-02-25
Publication date: 1991-09-25
Also published as: GB9103904D0; GB9004391D0

Abstract

A fluid valve comprises a body having an inlet (11) and an outlet (12) for fluid, a valve seat (13) between the inlet (11) and the outlet (12), and a valve member (14) movable from a first position in which fluid can flow from the inlet (11) to the outlet (12), past the valve seat (13), to a second position in which the valve member (14) is in engagement with the valve seat whereby the flow of fluid from the inlet (11) to the outlet (12) is prevented, and a valve actuating means comprising a control port (16) to which an actuating fluid is fed, means to direct the actuating fluid to a valve chamber (18) where the actuating fluid acts on a piston (20) which is secured relative to the valve member (14) to cause the piston (20) and hence the valve member (14) to move either from the first to the second or second to the first position, and actuating fluid bleed means (30) to release actuating fluid from the chamber, the actuating fluid bleed means comprising at least one passage through which the actuating fluid is released from the chamber. In an alternative valve actuating fluid is fed selectively, and alternately, to two chambers defined on either side of the piston. <IMAGE>

Description

Title: Valve for Fluid Description of Invention This invention relates to a valve for fluid and more particularly to a valve for fluid which is operated by an actuating fluid at a control pressure.

Such valves for fluid conventionally comprise a piston which is movable by the actuating fluid either in one direction only against the force of a spring for example (a single acting valve) or in both directions by applying actuating fluid selectively to one or other side of the piston (a double acting valve) to control the now of fluid through the valve.

The flow of actuating fluid to the valve may be controlled remotely from the valve, by a control valve, automatically or manually as desired.

It will be appreciated that in each case when it is desired either to allow the piston te return to an open or closed position under the power of a spring, or to move the piston in a reverse direction by actuating fluid, it is necessary to release actuating fluid from the valve so that the actuating fluid does not oppose piston movement.

Conventionally, this is achieved by the control valve which is either a three port control valve where the fluid valve is single acting, one of the ports being a drain port through which actuating fluid may pass when actuating fluid is no longer being fed at the control pressure to the fluid valve, to permit the release of actuating fluid from the fluid valve, or a five port control valve where the fluid valve is double acting, one of the ports providing for the release of actuating fluid from either side of the piston of the fluid valve to allow the piston to move freely when actuating fluid is no longer being fed at the control pressure to a respective same side of the piston of the fluid valve. Three port control valve and five port control valves are necessarily complex mechanisms.

According to one aspect of the invention I provide a valve for fluid comprising a body having an inlet and an outlet for fluid, a valve seat between the inlet and the outlet, and a valve member movable from a first position in which fluid can flow from the inlet past the valve seat to the outlet, to a second position in which the valve member is in engagement with the valve seat whereby the flow of fluid from the inlet to the outlet is at least reduced, and a valve actuating means comprising a control port to which an actuating fluid is fed at a control pressure, means to direct the actuating fluid from the control port to a valve chamber where the actuating fluid operates on one side of a piston which is secured relative to the valve member to cause the piston and hence the valve member to move either from the first to the second, or from the second to the first position, and actuating fluid bleed means to release actuating fluid from the chamber, the actuating fluid bleed means comprising at least one sized opening (as herein defined).

Thus a simple two port control valve can be used to control the supply of actuating fluid to the fluid valve where the fluid valve is single acting because when the control valve closes, such that actuating fluid is no longer being fed to the control port at the control pressure, the actuating fluid in the chamber of the fluid valve can bleed away through the actuating fluid bleed means, thus freeing the piston for movement by the spring.

Where the fluid valve is double acting, two two port control valves or one three port control valve, may be used because when the control valve closes to stem the flow of actuating fluid at the control pressure to one side of the piston of the fluid valve, the actuating fluid in the chamber at the one side of the piston can bleed away from the chamber to free the piston for movement by actuating fluid acting on the opposed, second, side of the piston.

By altering the dimension of the sized opening, or the number of sized openings provided, it is possible to affect the rate at which actuating fluid bleeds away from the chamber so that the time for which the valve member is held in its first or second position by actuating fluid at pressure in the chamber, can be altered.

According to a second aspect of the invention, we provide a fluid valve control system comprising a fluid valve according to the first aspect of the invention, and a control valve, the control valve having an inlet for actuating fluid and an outlet for actuating fluid which is connected to the control port of the fluid valve, a valve seat in the control valve between the inlet and the outlet thereof, and a valve member movable between an open position in which actuating fluid is permitted to flow through the control valve from the inlet to the outlet, and a closed position in which the valve member engages with the ive seat to prevent the flow of actuating fluid through the control valve to the fluid valve, operating means to move the valve member of the control valve between its open and closed positions.

Throughout the specification by "sized opening" we mean an opening which is significantly smaller in cross sectional area than the cross sectional area of the control port By significantly smaller, we mean at least 10 times smaller or preferably at least 100 timeS smaller, so that actuating fluid can only pass from the chamber at a controlled rate significantly slower than the rate at which fluid is delivered to the control port.

Thus the existence of the sized opening does not affect the normal operation of the valve i.e. the sized opening has no significant effect on the ability of the actuating fluid to move the piston against the force of a spring for example.

The invention will now be described with reference to the accompanying drawings in which: FIGURE 1 is a cross sectional view through a fluid valve in accordance with the invention, FIGURE 2 is a diagrammatic illustration of a control system incorporating the fluid valve of figure 1.

Referring to figure 1, there is shown a fluid valve 10 which comprises an inlet 11 for fluid, and an outlet 12 for fluid.

Between the inlet 11 and the outlet 12, there is a valve seat 13 past which the fluid must flow in order to pass from the inlet 11 to the outlet 12.

A valve member 14 is provided which, when in a first, rest, position as shown, is in engagement with the valve seat 13 and thus prevents the flow of fluid.

An actuating mechanism is provided to move the valve member 14 from engagement with the seat 13 to permit fluid flow through the valve 10.

The actuating mechanism comprises a control port 16 through which an actuating fluid can be supplied, at a control pressure. A duct 17 permits the actuating fluid to pass from port 16 to a chamber 18 within the valve where it can act on the underside of a piston 20 which is secured relative to the valve member 14 via an actuating rod 21.

On the opposite side of the piston, a restoring force is provided by means of a coil spring 22 which will tend to urge the piston 20 back to the position shown, again to bring the valve member 14 into sealing engagement with the seat 13.

It will be appreciated that the control pressure at which the actuating fluid is supplied to port 16 must be sufficient to overcome the restoring force of spring 22 in order to cause the valve member 14 to move to its second position when fluid flow through the valve is permitted.

Referring now also to figure 2, it can be seen that the actuating fluid is supplied to the control port 16 from a control valve 25 which comprises an inlet 26 for actuating fluid supplied under pressure from a pump P, and an outlet 27, which in this example, is connected directly by a line 30 to the control port 16.

The control valve 25 is of conventional construction and includes an electrical operating means to move a valve member of the control valve 25 from an open position when fluid flow through the control valve 25 from inlet 26 to outlet 27 is permitted past a valve seat of the control valve, to a closed position in which the valve member is in engagement with the valve seat to stem the flow of fluid.

The operating means of the control valve 25 may be controlled by a timer 28 so that the valve member of the control valve 25 can be caused to move to its open from its closed position at set intervals.

Preferably the timer 28 is of the type in which the set interval can be adjusted by means of a control knob 29.

It will be appreciated by those skilled in the art that when the valve member of the control valve 25 is moved to a closed position, ordinarily, the pressure of actuating fluid within the line 30 between the outlet 27 of the control valve 25 and the control port 16, in duct 17 and in the chamber 18 of the fluid valve 10, will be retained and thus the valve member 14 of the fluid valve tO will remain in its second, open condition. Over a considerable period of time, the fluid in chamber 18 may leak away so as to permit the spring 22 slowly to return the valve member 14 to its first, closed position as shown in the drawings. However, more usually, a control valve would be provided which has a third, drain port, rather than simply two ports 26 and n as with the control valve 25 described above.The third port would provide a drain facility to permit this residual pressure of the actuating fluid in line 30, duct 17 and chamber 18 of the fluid valve, to be released immediately when the flow of fluid through the control valve 25 to the fluid valve 10 is stemmed.

However, such three port control valves are unnecessarily expensive and complex In accordance with the invention, the fluid valve 10 is provided with an actuating fluid bleed means, to allow actuating fluid to be released from chamber 18 so that when actuating fluid is no longer being fed at the control pressure to port 16, the piston 20 and hence valve member 14 can be returned to its rest position by the force of spring 22. This is achieved by providing a passage means 30 through the piston 20, - to provide a path for actuating fluid which extends from the chamber 18 into a vented space 31 in which the spring 22 is located in this example.

The passage means 30 comprises a sized opening which allows actuating fluid to be bled from chamber 18 at a controlled rate significantly slower than the rate at which fluid is delivered to the control port 16.

Thus the existence of the passage means 30 does not affect the normal operation of the valve i.e. the passage means 30 has no significant effect on the ability of the actuating fluid delivered to control port 16 to move the valve member 14 away from seat 13 against the force of spring 22.

The valve 10 is of the so-called single acting type in that an actuating fluid is used only to move the piston 20 in one direction, the piston 20 being returned in the opposite direction by means of the spring 22.

If desired, the invention may be applied to a fluid valve of the double acting type which would have a second control port like port 16, arranged to receive actuating fluid at a control pressure and deliver the fluid to a second chamber arranged on the opposite side of the piston to the first mentioned chamber 18 served by the first control port 16.

A passage means like passage means 30 can still be provided through the piston 20 so as to allow for the controlled flow of actuating fluid from the chamber on one side of the piston to the chamber on the other side of the piston.

Such a double acting valve would be controlled either by two control valves like valve 25 shown in figure 2, one of the control valves supplying fluid under pressure to the first control port, and the other control valve 25 supplying fluid under pressure to the second control port, or alternatively, a single three port control valve could be provided, one of the ports comprising an inlet to which actuating fluid is supplied under pressure, and each of the other ports comprising a respective outlet port connected to one or other of the control ports.

The three way control valve would be capable of providing actuating fluid either to one or other of the outlet ports, when a valve member of the control valve is in an open position for example, or for preventing the supply of actuating fluid to either of the outlets thereof when a valve member thereof is in a closed position.

In all of the embodiments described, it will be appreciated that it is not essential that the passage means 30 for the release of actuating fluid from the chamber 18 or chambers of the valve comprises a single sized opening as described.

Any number of sized openings may be provided for actuating fluid from the chamber provided that in total, the sized openings do not materiaIly effect the normal operation of the valve.

Instead of the passage means comprising a sized opening through the piston 20 of the valve, if desired, the opening could be provided from the chamber 18 through the body of the valve 10 to the outside, or even along the rod 21 of the valve which connects the piston 20 and valve member 14, to a position from where the actuating fluid can be vented.

In the example shown, the fluid valve 10 is adapted to control the flow of pneumatic fluid having a pressure of up to 290 pounds per square inch, the control port 16 requiring a pneumatic fluid at a control pressure of at least 50 pounds per square inch to overcome the restoring force of the spring 22.

It has been found empirically that a passage means 30 having a diameter of about 1 mm allows for sufficient flow of the actuating fluid from the chamber 18 for the piston 20 to return to the position shown in figure 1 in which the valve 10 is closed, in a relatively short space of time.

However, it is envisaged that a larger passage means having a diameter of up to 2 mm could satisfactorily be provided.

In the example shown, the control part 16 has an internal diameter of about jh inch such that the cross sectional area of a single 1 mm diameter sized opening in passage 30, is at least 100 times smaller than the cross sectional area of port 16. However, other sized ports 16 and sized openings can be provided, although the cross sectional area of the sized opening or the total cross sectional areas of each of the sized openings, is preferably at least 10 times smaller than the cross sectional area of port 16.

Various other modifications are possible to valve 10 described, without departing from the scope of the invention. For example, instead of coil spring 22, any other resilient spring means could be provided. The inlet 11 need not be in line with outlet 12 as shown.

Further, the timer 18 of the system of figure 2 need not be integral with control valve 25, but may be separate therefrom. In this way, a single timer 28 can be used to control a plurality of control valves 25 which may thus control a plurality of fluid valves in accordance with the invention e.g. like valve 10. Alternatively or additionally, a simple control valve 25 can be used to control a plurality of fluid valves in accordance with the invention.

Although the fluid valve 10 described, and the control system, are for pneumatic fluid, the invention may be applied to the control of a hydraulic or other fluid as desired, although preferably, but not essentially, the actuating fluid is conveniently air or other pneumatic fluid.

The features disclosed in the foregoing description or the accompanying drawings or the following claims, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a calss or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A valve for fluid comprises a body having an inlet and an outlet for fluid, a valve seat between the inlet and the outlet and a valve member movable from a first position in which fluid can flow from the inlet past the valve seat to the outlet, to a second position in which the valve member is in engagement with the valve seat whereby the flow of fluid from the inlet to the outlet is at least reduced, and a valve actuating means comprising a control port to which an actuating fluid is fed at a control pressure, means to direct the actuating fluid from the control part to a valve chamber where the actuating fluid actuates on one side of a piston which is secured relative to the valve member to cause the piston and hence the valve member to move either from the first to the second, or from to the second to the first, position, and actuating fluid bleed means to release actuating fluid from the chamber, the actuating fluid bleed means comprising at least one sized opening (as herein defined).

2. A valve according to claim 1 which is single acting, there being a resilient means acting on the piston to urge the piston and hence the valve member towards the first or second position in an opposite direction to the actuating fluid.

3. A valve according to claim 2 when the resilient means comprises a coil spring.

4. A valve according to claim 2 or claim 3 wherein the actuating fluid bleed means comprises a passage means through the piston into a vented space at the side of the piston opposite to the chamber.

5. A valve according to claim 2 or claim 3 wherein the actuating fluid bleed means comprises a passage means through the body of the valve to the outside.

6. A valve according to claim 1 which is double acting, there being a second control port to which actuating fluid is fed to move the piston either from the second to the first, or from the first to the second, position, respectively.

7. A valve according to claim 6 wherein a second chamber is provided at the opposite side of the piston to the first mentioned chamber, actuating fluid being directed from the second port to the second chamber where the actuating fluid operates on the piston.

8. A valve according to claim 7 wherein the actuating fluid bleed means comprises a passage means from the first mentioned chamber, to the second chamber, through the piston.

9. A fluid valve substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

10. A fluid valve control system comprising a fluid valve according to any one of the preceding claims1 and a control valve, the control valve having an inlet for actuating fluid at an outlet for actuating fluid which is connected to the control port of the fluid valve, a valve seat in the control valve between the inlet and the outlet thereof, and a valve member movable between an open position in which actuating fluid is permitted to flow through the control valve from the inlet to the outlet, and a closed position in which the valve member engages with the valve seat to prevent the flow of actuating fluid through the control valve to the fluid valve, operating means to move the valve member of the control valve between its open and closed positions.

11. A system according to claim 10 wherein the operating means of the control valve is electrically actuated

12. A system according to claim 11 wherein the operating means comprises an electrically actuated timer which is arranged to move the valve member between its open and closed positions repeatedly at set intervals.

13. A system according to claim 12 wherein the set intervals are adjustable.

14. A system according to any one of claims 10 to 13 wherein the fluid valve is of the double acting type and there is provided a second control valve in the system which also has an inlet for actuating fluid and an outlet for actuating fluid which is connected to a second control port of the fluid valve, the second control valve having a valve seat between the inlet and the outlet thereof and a valve member movable between an open position in which actuating fluid is permitted to flow through the second control valve from the inlet to the outlet thereof, and the closed position in which the valve member is in engagement with the vale seat to prevent the flow of actuating fluid through the second control valve, operating means to move the valve member between its open and closed positions.

15. A system according to any one of claims 10 to 13 wherein the fluid valve is of the double acting type and the control valve comprises a second outlet port to which actuating fluid from the inlet may be fed, the second outlet port being connected to a second control port of the fluid valve to move the piston of the fluid valve between the second and first positions, the operating means selectively diverting the actuating fluid from the inlet to the first mentioned outlet or the second outlet when the valve member is in its open position

16. A control system according to any one of claims 10 to 15 wherein the actuating fluid is provided to the control port, and second control port where provided, at a pressure less than a 100 pounds per square inch.

17. A fluid valve control system substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

18. Any novel feature or novel combination of features as herein described and/or shown in the accompanying drawings.