GB2378263A

GB2378263A - Fluid control valve

Info

Publication number: GB2378263A
Application number: GB0212334A
Authority: GB
Inventors: Anthony Cowan
Original assignee: G&K Valve Services Ltd
Current assignee: G&K Valve Services Ltd
Priority date: 2001-05-29
Filing date: 2002-05-29
Publication date: 2003-02-05
Also published as: GB0112927D0; GB0212334D0

Abstract

A fluid control valve (1) has a valve body (2) which defines an inlet (6) and an outlet (8). Slidably positioned in the valve body (2) is a piston member (20) which moves between first and second positions which correspond to open and closed states of the valve (1). The piston member (20) has a chamber (28) which is in communication with both the inlet (6) via a fixed size first aperture (36) and also the outlet (8) via a second aperture (46) which is controlled by a pilot valve arrangement (34). By adjusting the position of the pilot valve (34) in the second aperture (46), the hydraulic pressure in the chamber (28) can be adjusted so that the piston member (20) moves towards either the first or second position, thereby controlling fluid flow through the control valve.

Description

CONTROL VALVE 1 The present invention is directed to a control 2 valve, and in particular to a control valve for use 3 in liquid supply pipelines.

4 5 In order to control flow in liquid supply pipelines, 6 it is necessary to use valves that can not only 7 shut-off flow, but which can also reduce liquid 8 pressure in the pipelines without necessarily 9 stopping flow altogether. Known valves that are 10 used for this purpose are generally mechanically 11 actuated and as such require some externally-powered 12 mechanism in order to control the operation of the 13 valve. Commonly, in water supply pipelines, for 14 example, a control panel or box located at ground 15 level in the vicinity of the underground supply line 16 is provided in order to control the valves. Each 17 valve will be linked to the control box such that a 18 signal from the box will lead to an electric motor 19 moving the valve member toward either the closed or 20 open position depending on the signal received.

1 However, at present such instructions must be input 2 manually by an operator at the control box.

3 4 Known mechanically actuated control valves therefore 5 require a powerful external motor to operate the 6 valve, which does not make the valve particularly 7 efficient. Furthermore, these known valves are not 8 especially accurate and their response times are 9 slow.

10 11 It is therefore an aim of the present invention to 12 provide a control valve that obviates or mitigates 13 one or more of the aforementioned disadvantages.

14 The control valve of the present invention will 15 require little external power to operate, and will 16 also provide accurate and instantaneous operation of 17 the valve compared with known arrangements.

18 19 According to the present invention, there is 20 provided a fluid control valve comprising: 21 a valve body having an inlet and an outlet ; 22 a piston member slidingly engaged in said valve 23 body such that said piston member is movable between 24 first and second positions, the first and second 25 positions corresponding to open and closed states of 26 the valve, respectively ; 27 wherein the piston member is provided with a 28 closing hydraulic surface, a lifting hydraulic 29 surface and a chamber, the chamber having a first 30 aperture in fluid communication with said inlet and 31 a second aperture in fluid communication with said 32 outlet ; and

1 wherein the control valve further comprises a 2 pilot valve adapted to adjust the diameter of the 3 second aperture such that hydraulic pressure acts 4 upon either the lifting hydraulic surface or the 5 closing hydraulic surface to actuate the piston 6 member towards either the first or second position 7 dependant on the position of said pilot valve.

8 9 Preferably, the closing hydraulic surface is located 10 in the chamber.

11 12 Preferably, the pilot valve is movable between 13 positions where the second aperture is fully closed 14 and where the second aperture is fully open and one 15 or more intermediate positions therebetween.

16 17 Preferably, the control valve further comprises a 18 data processing means adapted to control the pilot 19 valve, the data processing means including a memory 20 device, a processor in communication with said 21 memory device and at least one pressure sensor in 22 communication with said processor. Preferably, the 23 sensor is located adjacent said outlet.

24 25 Preferably, the valve further comprises a two-way 26 motor in communication with said data processing 27 means for providing an actuating force to the pilot 28 valve.

29 30 In a preferred embodiment, the processor contains a 31 clock function, and said memory device stores a

1 program and predetermined values of pressure for 2 different times of day.

3 4 Preferably, the data processing means has an 5 override function and is remote controlled.

6 7 In a preferred embodiment, the data processing means 8 includes first and second sensors adjacent said 9 inlet and outlet, respectively, each sensor being in 10 communication with said processor. The data 11 processing means may also further comprise a flow- 12 meter adjacent said outlet and in communication with 13 said processor.

14 15 Preferably, the piston member is movable between one 16 or more intermediate positions between the first and 17 second positions, corresponding to one or more 18 partially open states of the valve.

19 20 A preferred embodiment of the present invention will 21 now be described, by way of example only, with 22 reference to the accompanying drawings, in which: 23 24 Figure 1 shows a cross-sectional view of a 25 control valve in accordance with the present 26 invention with the valve in the open state ; and 27 28 Figure 2 shows the same cross-sectional view of 29 the control valve of Fig. 1 with the valve in the 30 closed state.

31

1 Figs. 1 and 2 shows a preferred embodiment of the 2 present invention, wherein a liquid control valve 1 3 for use in a water supply pipeline is shown in 4 cross-section. The valve 1 includes a valve body 2 5 having a neck portion 4, an inlet 6 and an outlet 8.

6 The body 2 is formed such that it comprises a 7 predominantly spherical chamber 10 that is split 8 into an inlet chamber 12 and an outlet chamber 14 by 9 an integral partition 16 which lies across the 10 entire diameter of the spherical chamber 10. An 11 annular aperture 18 is provided in the partition 16 12 for fluid communication between the inlet chamber 12 13 and the outlet chamber 14.

14 15 An annular piston member 20 is located in the neck 16 portion 4 of the valve body 2 such that it extends 17 down into the chamber 10 and through the annular 18 aperture 18 of the partition 16. In this manner, 19 the piston member 20 controls the fluid 20 communication between the inlet chamber 12 and the 21 outlet chamber 14. The piston member 20 is 22 slidingly engaged in the valve body 2, so that it 23 may move between a first position where the valve is 24 open (Fig. 1) and a second position where the valve 25 is closed (Fig. 2), or vice versa. Furthermore, the 26 piston member 20 may move to any intermediate 27 position between the first and second positions, as 28 required. With the piston member 20 located in the 29 neck portion 4 of the valve body 2, an annular space 30 22 is created between the inner wall 23 of the neck 31 portion 4 and the outer wall 25 of the piston member 32 20. The piston member 20 also comprises an annular

1 piston cup seal 24 at the uppermost point thereof, 2 which creates at watertight seal between the piston 3 member 20 and the valve body 2..

4 5 The piston member 20 has an annular closure 26 6 fitted on top of the piston cup seal 24. Along with 7 the side walls of the piston member 20, the closure 8 26 defines an actuation chamber 28 within the upper 9 portion of the piston member 20. The outer wall 25 10 of the piston member 20 contains an aperture 36 so 11 that water flowing in through the inlet 6 may flow 12 into the actuation chamber 28 from the annular space 13 22. The lower portion of the piston cup seal 24 14 includes a lifting hydraulic surface 31. The base 15 of the interior of the chamber 28 has a closing 16 hydraulic surface 29. The closure 26 is provided 17 with a central aperture 30 that also has a guide 18 means 32 in order that a pilot valve 34 may extend 19 through the closure 26 into the actuation chamber 28 20 of the piston member 20, as will be explained in 21 detail below. With the piston cup seal 24 in 22 position, water can only pass from the annular space 23 22 into the actuation chamber 28 by way of the 24 aperture 36 and no water can pass back out of the 25 actuation chamber 28 into the annular space 22.

26 27 In the lower portion of the piston member 20 is 28 provided a gate portion 38 through which the water 29 flows when the valve is in any position other than 30 the fully closed position. The gate portion 38 is 31 provided with a number of slot-shaped apertures (not 32 shown) about its circumference through which water

1 may flow from the inlet chamber 12 to the outlet 2 chamber 14 when the valve member is in the open 3 position. Guides 40 are provided in the gate 4 portion 38 to help direct the water flow through the 5 piston member 20. By providing the slot apertures, 6 the amount of water flowing between inlet and outlet 7 may be regulated, with maximum flow only being 8 possible when the valve is fully open.

9 10 The piston member 20 is provided with an annular 11 flange 42 between the actuation chamber 28 and the 12 gate portion. The flange 42 is provided with a seal 13 44 on its underside such that when the piston member 14 20 is in the closed position, as in Fig. 2, no water 15 may flow through the gate portion 38 from the inlet 16 chamber 12. However, a central passage 46 having an 17 aperture 47 is provided down through the piston 18 member 20 from the actuation chamber 28 into the 19 outlet chamber 14 such that water may flow from the 20 actuation chamber 28 into the outlet chamber 14 21 under the control of the aforementioned pilot valve 22 34.

23 24 The neck portion 4 of the valve body 2 is sealed 25 with a cover 56 that is fixed to the top of the 26 valve body 2 by bolts 58. The cover 56 is provided 27 with an opening 60 in which the pilot valve 34 is 28 located so that the pilot valve 34 may lie in the 29 actuation chamber 28 when the cover 56 is fitted. A 30 seal 61 in the opening 60 prevents any loss of water 31 through the opening 60 when the pilot valve 34 is in 32 position.

1 2 The pilot valve arrangement will now be described in 3 more detail. The pilot valve 34 is provided so as 4 to control the opening and closing of the piston 5 member 20. The pilot valve arrangement has a 6 housing 48 which is either fixed or removably 7 attached to the top of the cover 56. Located in the 8 housing 48 are a DC motor 50 and a gear mechanism 9 52. The pilot valve 34 itself is comprised of a 10 threaded stem 54 which has a tapered stopper 62 11 attached to its base such that the end of the 12 stopper 62 sits in the aperture 47 of the central 13 passage 46 that runs between the actuation chamber 14 28 and the outlet chamber 14. The DC motor 50 15 dictates the movement of the pilot valve 34 via the 16 gear mechanism 52. Therefore, the stem 54 may rise 17 or fall depending on the direction of rotation of 18 the gear mechanism 52 as dictated by the DC motor 19 50, thereby moving the stopper 62 up or down 20 relative to the aperture 47 of the passage 46.

21 Thus, the stem 54 and stopper 62 control the amount 22 of water passing from the actuation chamber 28 23 through the passage 46 to the outlet chamber 14.

24 25 The DC motor 50 itself is controlled by signals 63 26 received from a data processing means such as a 27 programmable logic controller (PLC) 64. The PLC 64 28 receives signals 65,67 from first and second 29 pressure sensors 66,68 located adjacent the inlet 30 and outlet 6,8 of the valve 1, respectively. The 31 PLC 64 then sends a signal 63 to the DC motor 50 to 32 adjust the pilot valve 34 accordingly. It should be

1 noted that the PLC 64 may also receive signals from 2 only one sensor 68 adjacent the outlet 8, depending 3 on the application.

4 5 The operation of the control valve 1 will now be 6 described, again with reference to Figs. 1 and 2.

7 The purpose of the valve is to provide a fully 8 automated control valve which can automatically 9 adjust itself without manual intervention. It may 10 either (i) maintain a constant water pressure at the 11 outlet 8, or (ii) adjust the water pressure at the 12 outlet 8 depending on the amount of water required 13 at a particular time of day.

14 15 In general operation, where the valve is open as in 16 Fig. 1, water flows from the inlet chamber 12 17 directly through the apertures in the gate portion 18 38 to the outlet chamber 14. However, at the same 19 time, water also flows into the annular space 22 20 between the neck portion 4 of the valve body 2 and 21 the piston member 20. The water that flows into 22 this space 22 also flows through the aperture 36 23 into the actuation chamber 28. The actuation 24 chamber 28 and pilot valve 34 are what controls the 25 positioning of the piston member 20. However, key 26 to the operation is the relationship between the 27 size of the aperture 36 in the outer wall 25 of the 28 piston member 20 and the size of the aperture 47 of 29 the central passage 46.

30 31 The size of the aperture 47 of the passage 46 is 32 determined and adjusted by the stopper 62 of the

1 pilot valve 34. When the pilot valve 34 and stopper 2 62 are in such a position that the size of the 3 aperture 47 and the size of the aperture 36 are the 4 same, the piston valve 20 is balanced and will not 5 move. However, when the size of the aperture 47 is 6 reduced by the pilot valve 34 to a smaller size than 7 the aperture 36, the resultant increase in water 8 pressure against the closing hydraulic surface 29 in 9 the actuation chamber 28 forces the piston member 20 10 downwards. This therefore reduces the amount of 11 flow through the previously fully open gate portion 12 38. If full closure of the valve 1 is desired, then 13 the stopper 62 of the pilot valve 34 can close the 14 aperture 47 completely. This will lead to the 15 piston member 20 being pushed all the way down to 16 the fully closed position due to the water pressure 17 on the closing hydraulic surface 29 in the actuation 18 chamber 28. The closed position of the valve 1 is 19 shown in Fig. 2.

20 21 When the valve 1 is to be opened again, the pilot 22 valve stopper 62 is moved upwards to open the 23 aperture 47 again, allowing water to flow again 24 through passage 46 and the hydraulic pressure in 25 chamber 28 to drop as a result. As the pressure 26 begins to drop in the actuation chamber 28, the 27 pressure of the water through the inlet 6 acts upon 28 the lifting hydraulic surface 31 of the piston cup 29 seal 24 attached to the piston member 20. The 30 piston member 20 will then rise under the action of 31 the pressure on the lifting hydraulic surface 31, 32 opening the gate portion 38 to the flow of water.

1 In this way, the valve operation is controlled by 2 the constant adjustment of the pilot valve 34 in the 3 actuation chamber 28.

4 5 In order to provide automatic adjustment of the 6 valve 1, the PLC 64 is provided. The PLC 64 7 contains a real time clock and a memory device, the 8 memory device containing a stored program which 9 stores the required water pressure at the valve 10 outlet 8 for various times of day. For example, the 11 required volume of water (and therefore water 12 pressure) will be very low at 3am, but will be very 13 high at 8am when the majority of water customers use 14 water. Based upon calculations made prior to 15 installation, the PLC 64 can be programmed with the 16 required pressure values which correspond to the 17 required water volumes, so that the PLC 64 knows 18 exactly what pressure is required at various points 19 throughout the day and night.

20 21 The PLC 64 adjusts the valve 1 by taking readings 22 from the pressure sensors 66,68 via signals 65,67.

23 Let us take the example where the pressure at outlet 24 sensor 68 is higher than the desired pressure stored 25 in the memory device for that particular time of 26 day. The sensor 68 sends its signal 67 to the PLC 27 64, and the PLC 64 compares the sensor pressure 28 value with that stored in its memory. Where the 29 value read by the sensor 68 is too high, the PLC 64 30 sends a signal 63 to the DC motor 50 to lower the 31 pilot valve 34 so that the size of the aperture 47 32 of the passage 46 is smaller than that of the fixed

1 size aperture 36. The DC motor 50 winds the gear 2 mechanism 52 that in turn lowers the stem 54 of the 3 pilot valve 34. Once the size of the aperture 47 is 4 smaller than that of the fixed aperture 36, the 5 building water pressure in the actuation chamber 28 6 will act upon the closing hydraulic surface 29, thus 7 forcing the piston member 20 lower. As the piston 8 member 20 lowers, less of the apertures in the gate 9 portion 38 will be exposed, and the amount of water 10 flowing through the gate portion 38 will therefore 11 be reduced. Thus, the water pressure at the outlet 12 8 will be reduced. Once the outlet sensor 68 sends 13 a signal 67 that the pressure has dropped to the 14 required level, the PLC 64 will then send a signal 15 63 to the DC motor 50 to hold the pilot valve 34 in 16 its current position, thereby balancing the piston 17 member 20 until a further change is required.

18 19 Thus, accurate and near-instantaneous response can 20 be obtained from the valve, without any need for 21 manual intervention at all. Through the readings of 22 the sensors 66,68 the valve can adjust at any time, 23 either to change the water pressure at the outlet 8, 24 or else to maintain a constant outlet pressure in 25 the face of fluctuating inlet pressures.

26 Furthermore, the stored values in the PLC can be 27 adjusted at any time from a central control unit, 28 without the need for any manual input at a control 29 box at ground level, as is presently the case.

30 31 The present invention further improves over existing 32 valves in that no high-powered external actuation

1 means is required to open and close the valve. The 2 low-powered DC motor provides enough power to move 3 the pilot valve, but the main force used to close 4 and open the valve is the hydraulic force provided 5 by the incoming water itself, by way of the 6 actuation chamber. Thus, the present invention is 7 not only more responsive and accurate, but is also 8 more efficient as it requires little power to 9 actuate the valve.

10 11 A further benefit of the present invention over 12 existing valves is that most existing valves as 13 simply pressure reducing valves. In contrast, the 14 present invention actively controls flow and can 15 adjust to any pressure depending on the instructions 16 given to the PLC.

17 18 Although the PLC is intended to operate using the 19 pair of pressure sensors at inlet and outlet or a 20 single outlet sensor, a flowmeter may also be added 21 at the outlet in place of, or in addition to, the 22 sensors. With the addition of a flowmeter, pipe 23 bursts may be detected. There can be various 24 reasons why the pressure would drop on the outlet 25 side of the valve, but if the flowmeter detected 26 that the flow remained constant despite the pressure 27 drop, then the PLC would recognise that a burst had 28 occurred downstream. Also, with the flowmeter, flow 29 through the valve may be directly monitored by the 30 PLC without the need for flow calculations based 31 upon the pressure sensor readings.

32

1 Furthermore, although a DC motor is the preferred 2 power source for operation of the pilot valve, any 3 power source can be used which permits two way 4 rotation. Also, any suitable processor may be used 5 in place of the PLC.

6 7 A yet further improvement would be to add additional 8 sensors, either in the pipeline or at suitable 9 points elsewhere in the supply line (e. g. reservoir) 10 to monitor water levels, in combination with one or 11 both of the pressure and flow sensors. Thus, if the 12 water level rose beyond a predetermined level in a 13 reservoir, for example, an override instruction 14 would be sent to the PLC to override the 15 predetermined program, thus preventing flooding.

16 17 With the additional sensors, the valve of the 18 present invention may undertake any of the following 19 tasks: monitoring level versus pressure, monitoring 20 flow versus pressure, monitoring flow versus level, 21 pipeline burst monitoring, pressure sustaining, 22 pressure relief and demand sensing.

23 24 It will be understood by those skilled in the art 25 that although the preferred embodiment of the 26 control valve is described above in a water supply 27 application, the valve of the present invention may 28 be used in the supply of any suitable liquid.

29 30 These and other modifications and improvements can 31 be incorporated without departing from the scope of 32 the invention.

Claims

CLAIMS:

1 1. A fluid control valve comprising:

2 a valve body having an inlet and an outlet ;

3 a piston member slidingly engaged in said valve

4 body such that said piston member is movable between

5 first and second positions, the first and second

6 positions corresponding to open and closed states of

7 the valve, respectively ;

8 wherein the piston member is provided with a

9 closing hydraulic surface, a lifting hydraulic 10 surface and a chamber, the chamber having a first 11 aperture in fluid communication with said inlet and 12 a second aperture in fluid communication with said 13 outlet ; and 14 wherein the control valve further comprises a 15 pilot valve adapted to adjust the diameter of the 16 second aperture such that hydraulic pressure acts 17 upon either the lifting hydraulic surface or the 18 closing hydraulic surface to actuate the piston 19 member towards either the first or second position 20 dependant on the position of said pilot valve.

21 22
2. The valve of Claim 1, wherein the closing 23 hydraulic surface is located in the chamber.

24 25
3. The valve of either preceding claim, wherein 26 the pilot valve is movable between positions where 27 the second aperture is fully closed and where the 28 second aperture is fully open and one or more 29 intermediate positions therebetween.

30

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1
4. The valve of any preceding claim, further

2 comprising a data processing means adapted to

3 control the pilot valve, the data processing means

4 including a memory device, a processor in

5 communication with said memory device and at least

6 one pressure sensor in communication with said

7 processor.

8

9
5. The valve of Claim 4, wherein said sensor is 10 located adjacent said outlet.

11 12
6. The valve of either Claim 4 or Claim 5, wherein 13 said valve further comprises a two-way motor in 14 communication with said data processing means for 15 providing an actuating force to the pilot valve.

16 17
7. The valve of any of Claims 4 to 6, wherein said 18 processor contains a clock function, and said memory 19 device stores a program and predetermined values of 20 pressure for different times of day.

21 22
8. The valve of any of Claims 4 to 7, wherein said 23 data processing means has an override function.

24 25
9. The valve of any of Claims 4 to 8, wherein said 26 data processing means is remote controlled.

27 28
10. The valve of any of Claims 4 to 9, wherein the 29 data processing means includes first and second 30 sensors adjacent said inlet and outlet, 31 respectively, each sensor being in communication 32 with said processor.

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1

2
11. The valve of any of Claims 4 to 10, wherein the

3 data processing means further comprises a flow-meter

4 adjacent said outlet and in communication with said

5 processor.

6

7
12. The valve of any preceding claim, wherein said

8 piston member is movable between one or more

9 intermediate positions between the first and second 10 positions, corresponding to one or more partially 11 open states of the valve.

12 13
13. A fluid control valve substantially as 14 hereinbefore described with reference to the 15 accompanying drawings.