CHECK VALVE

Abstract

A check valve (1) which comprises an obturator (2) and a biasing mechanism, the biasing mechanism arranged to urge the obturator towards a closed condition, and the check valve further comprising an actuator assembly (5, 7a, 7b) which is arranged to be selectively activated to cause the obturator to be in an open condition, and the check valve comprising a controller which has a control signal input to cause the controller to selectively activate the actuator assembly.

Claims

1. A check valve which comprises an obturator and a biasing mechanism, the biasing mechanism arranged to urge the obturator towards a closed condition, and the check valve further comprising an actuator assembly which is arranged to be selectively activated to cause the obturator to be in an open condition, and the check valve comprising a controller which has a control signal input to cause the controller to selectively activate the actuator assembly.

2. A check valve as claimed in claim 1 in which when the actuator assembly is activated the actuator assembly is arranged in use to override the biasing mechanism.

3. A check valve as claimed in claim 2 in which the controller is arranged to maintain the activation of the actuator assembly to hold the obturator in an open condition during operation of a fluid displacement device to urge fluid through a fluid port of the device, which fluid port the check valve is connected to.

4. A check valve as claimed in claim 3 in which the controller is arranged to de-activate the actuator assembly in response to receipt of a control input which is indicative of either a depowering of the fluid displacement device or of a change in operational status of the fluid displacement device from an operational condition to a non-operational condition.

5. A check valve as claimed in any preceding claim in which the actuator assembly arranged, when activated, to open the obturator to a greater extent from a partially open condition.

6. A check valve as claimed in any preceding claim in which the controller comprises a terminal or a port, which is arranged to receive an electrical signal, pneumatic or mechanical signal.

7. A check valve as claimed in any preceding claim in which the actuator assembly comprises a pressure-activated actuator.

8. A check valve as claimed in any preceding claim in which the controller is arranged to cause one of two fluid pressure sources to act at least in part on the actuator assembly.

9. A check valve as claimed in claim 8 in which connection of the actuator to one pressure source permits the biasing mechanism to operate, and connection to the other pressure source causes the obturator to be urged into the open condition.

10. A check valve as claimed in any of claim 8 or 9 in which the controller comprises a switch which is arranged to bring about control of which pressure source the actuator assembly is connected to.

11. A check valve as claimed in any preceding claim in which the actuator assembly comprises a motive component of which opposing sides or ends are arranged to be acted on by a respective pressure source, and the fluid pressure to which at least one of the sides/ends of the components is subjected to is controlled by the controller.

12. A check valve as claimed in claim 11 in which the controller is arranged to allow the motive component to be selectively subjected to a pressure differential in which one side/end of the motive component is subjected to a higher fluid pressure than the other side/end of the motive component.

13. A check valve as claimed in claim 12 in which the controller further allows both ends/sides of the motive component to be selectively subjected to substantially equal fluid pressures.

14. A check valve as claimed in claim 13 in which the check valve is such that the fluid pressure to which one side/end of the motive component is subjected to is not alterable to another pressure by the controller.

15. A check valve as claimed in claim 14 in which said side/end of the motive component may be substantially invariably be connected to a single fluid pressure source.

16. A check valve as claimed in any preceding claim in which the controller comprises a switching valve.

17. A check valve as claimed in any preceding claim in which the actuator assembly comprises a piston which is moveable within a piston chamber, and the piston defines two sub-chambers, a first sub-chamber which is selectively connectable to a first pressure and to a second pressure, and a second sub-chamber which is connected to the first pressure.

18. A check valve as claimed in claim 17 when appended to claim 14 in which the switching valve is arranged to control which of the first fluid pressure and the second fluid pressure is connected with the first sub-chamber.

19. A check valve as claimed in any preceding claim in which the actuator assembly comprises a first conduit which connects the controller to the first pressure and a second conduit which connects the controller to the second fluid pressure.

20. A check valve as claimed in claim 19 in which the controller comprises a third conduit which operatively connects the controller to the actuator assembly.

21. A check valve as claimed in any preceding claim in which, where reference is made to a first fluid pressure and a second fluid pressure, the first fluid pressure is lower than the second fluid pressure.

22. A check valve as claimed in claim 21 in which the first fluid pressure is atmospheric pressure and the second fluid pressure is the pressure of fluid in a fluid containing conduit to which the check valve is arranged to be operatively connected.

23. A check valve as claimed in any of claims 1 to 20 in which where reference is made to a first fluid pressure and a second fluid pressure, the first fluid pressure is greater than the second fluid pressure.

24. A check valve as claimed in claim 23 in which the first fluid pressure is atmospheric pressure and the second fluid pressure is a vacuum.

25. A check valve as claimed in any preceding claim which comprises a linkage which connects actuator assembly to the obturator.

26. A check valve as claimed in any preceding claim in which the controller is arranged to de-activate the actuator assembly in response to an absence of a signal input to the controller indicative of the operation of a fluid displacement device, a fluid port of which the check valve is connected to.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Various embodiments of the invention will now be described by way of example only in which:

[0063] FIG. 1 is a perspective external view of a check valve,

[0064] FIG. 2 is a perspective view demonstrating various internal components of the check valve,

[0065] FIG. 3 is a longitudinal cross-section of the check valve,

[0066] FIG. 4 is an enlarged view of a solenoid control assembly of the check valve,

[0067] FIG. 5 is schematic diagram of check valve, and

[0068] FIG. 6 shows the check valve connected to the fluid outlet of a compressor.

DETAILED DESCRIPTION

[0069] There is now described a check valve which comprises an obturator (or flap) which is moveable from an open condition to a closed condition and vice versa, and a pressure-activated actuator (which may be termed a secondary activation mechanism) which causes the obturator to be selectively held in an open condition, and in use overriding the biasing mechanism and its tendency to urge or move the flap element to a close d condition. The embodiment described below is in relation to the check valve provided at or connected to an outlet of an air compressor.

[0070] Reference is made to FIGS. 1 and 2. The main body or carcass of the check valve 1 is similar to a traditional check valve: it comprises a flap 2, which closes under its own weight (or by/in addition to a spring force, which could be a coil spring or an air spring). The check valve could also be of the butterfly valve type. The check valve 1 comprises a fluid inlet 1a and a fluid outlet 1b.

[0071] The flap 2 is mounted on a pivot shaft 3. The pivot shaft 3 allows the flap to rotate about an axis from an opened condition to a closed condition and vice versa.

[0072] In the illustrated example, the secondary activation mechanism referred to above comprises a piston 5 which is moveable in a cylinder 6. The piston is connected to an articulated linkage which comprises a piston rod 7a and an arm 7b, and the parts 7a and 7b pivotably connected. The arm 7b is fixedly connected to the shaft 3, such that activation of the actuator assembly drives/causes movement of the piston to cause the flap 2 to open.

[0073] The piston 5 divides the cylinder space into two sub-chambers. One side of the piston 5 (shown as the upper part in the Figures, although orientation is not important) is always connected to atmosphere or atmospheric pressure through a vent 10. The other side of the piston 5, i.e. the lower sub-chamber as illustrated, can be selectively connected to either atmospheric pressure or the pressurised fluid (i.e. compressed air) in the pipe to which the valve 1 is connected. The pipe is connected to a fluid outlet of a compressor, and the valve located downstream of the compressor. The piston 5 is sealed to the cylinder 6 to prevent leakage of the compressed air to atmosphere. The connection to the pipe is provided on the inlet side of the flap 2, to allow the flap to function initially if the pipeline starts off at atmospheric pressure.

[0074] The check valve 1 further comprises a control signal port or terminal 12 which is arranged to receive a signal (directly or indirectly) from a compressor. The input to the port 12 controls the function of a solenoid switching valve, illustrated schematically at 13. The valve contains a solenoid which is configured to switch the source of pressure to which the lower sub-chamber of the chamber 6 is connected. The switching valve 13 is connected to atmospheric pressure by way of a conduit or inlet 13a, and is also connected to the pressure of air within the pipe which has been output by the compressor by way of a conduit 13b. The conduit 13b connects an aperture in the body of the check valve located upstream of the flap 2, as best seen in FIG. 3, to the switching valve 13. The switching valve 13 further comprises an outlet 13c, which fluidically connects to the lower sub-chamber of the cylinder 6.

[0075] The vent 10 and the inlet 13a being connected to atmospheric pressure may be thought of more generally as being connected to a reference pressure, which allows a pressure differential to be achieved, as is described in more detail below. Moreover, the vent 10 and 13a may be connected to an inlet of the compressor. This is advantageous in the case of the use of a toxic gas, which would otherwise be vented to atmosphere can instead be contained with the fluid system.

[0076] Specifically, the terminal 12 is arranged to receive a signal which is indicative of whether a power supply to the compressor changes from an ON state to an OFF state, or the compressor otherwise ceases operation (at least as far as delivering compressing air). Receipt of a signal indicative of a state transition causes the secondary activation mechanism to be energised. In practice, this control of the check valve 1 may be achieved by the actuator causing the flap 3 to remain in an open condition as long as a signal is received which is indicative of the compressor's compression function being in operation/running so as to deliver/output compressed air. In the absence of receipt of such a signal at the terminal 12, the solenoid of the switching valve is configured to cause the pressure source to the lower sub-chamber to be connected to atmospheric pressure. Alternatively, a predetermined signal may be output to the terminal 12 which is indicative of a change of operational status of the compressor to a powered down or OFF condition, in relation to its compression delivery functionality. Therefore, the input terminal 12 is connected, directly or indirectly, to the compressor so as to effect the control of the actuator. Thereby, the operational mode of the valve is dependent on the operational status of the compressor.

[0077] The switching valve 13 comprises a single 3-port solenoid activated valve. It will be appreciated that the switching valve could also be a valve(s) operated by means other than electrical activation, such as mechanical, hydraulic or pneumatic means. For example, the respective sub-chamber of the actuator assembly could be connected by a conduit to the fluid displacement device and then to a pressure sensor which outputs a signal to the controller.

[0078] The switching valve 13 may alternatively comprises two solenoid-operated air control valves which change the medium to which the lower side of the cylinder 6 is connected to. One of the valves is normally open; the other is (normally) closed. When no electrical signal is applied, the valves default to these positions. When electrical signal is applied, they assume the opposite state.

[0079] When no electrical signal is applied via the input terminal 12, the check valve 1 operates as a conventional check valve: it opens when pressure at the inlet is greater than at the outlet, and closes when the opposite is true. The movement is caused by the pipeline pressure acting across the flap, causing it to lift open when the pump starts, begins dropping under its own weight and/or the action of a spring when the flow is reversing, and closes fully due to reversal of pressure across it. Since the lower portion of the cylinder 6 is connected by the valve 13 to atmosphere (the top sub-chamber is always connected to atmosphere), there is no significant force acting on the piston 5, apart from some damping due to the small air passages of the secondary activation system. The piston 5 (which is mechanically linked to the flap of the check valve) is moved by the flap, and applies only a small damping force on the flap 2.

[0080] When an electrical signal is applied in response to a signal being received at the terminal 12, the solenoid causes the air valves to disconnect the air below the piston 5 from the atmosphere and instead connect it to the air in the pipe which is just upstream of the flap in the main pipe. This means that so long as the pressure in the pipe is higher than atmospheric pressure, there will be an upward force on the piston at all positions of the flap 2, causing the flap to be open (and remain open). The piston 5 and its linkage 7a and 7b to the flap are dimensioned (by way of respective surface areas) so that the expected pipeline pressure during all operating conditions is sufficient to keep the flap fully open (to counteract the closing force of its weight and/or any attached spring). Since the flap 2 is fully open, it does not cause a pressure drop to the fluid flowing in the main pipe. Conversely, the flow in the pipe applies very little force to the flap, and its position is controlled primarily by the piston 5. The piston area can be smaller than the flap 2 area.

[0081] Thus when the electrical signal is applied, the check valve 1 will not function as a normal or regular check valve, because it will not partially close when a low-pressure rarefaction passes through it (as long as the lowest pressure in the pulse is still above atmospheric, and sufficient to keep the piston at the top of its stroke by resisting the closing force of the flap). The flap will also not close in case of a flow reversal, as the pressure in the pipe will likely still be above atmospheric even if the flow reverses (this will be the case until the pipe network has fully drained to come down to atmospheric pressure).

[0082] This means that by applying the electrical signal, the non-return nature of the valve is overridden or bypassed, and in almost all circumstances (while the electrical signal is applied) it becomes a manually or forced opened valve (with no capability to manually close it). To satisfy the non-return criteria of a check valve to protect the pipeline and compressor, the electrical signal is disconnected when any issues arise. This can be achieved by using a range of sensors on the compressor and/or the pipeline, as well as by connecting the valve to the same electrical supply as the compressor. These serve as protective measures (which cause the check valve to adopt its passive mode) and may include determining that when power is lost, for example.

[0083] Reference is made to FIG. 6 which shows the check valve 1 connected to a fluid outlet of a rotary piston and cylinder device 50.

[0084] It will be appreciated that the obturator 2 in FIGS. 2, 3 and 4 is in a closed condition. In FIG. 5, the obturator 2 is shown in a partially open condition as a result of the pressure applied by the fluid flow, but without the assistance of activation of the actuator.