GB2255424A

GB2255424A - Fluid flow control valves

Info

Publication number: GB2255424A
Application number: GB9209138A
Authority: GB
Inventors: David Kenneth Durrant
Original assignee: Delta Engineering Holdings Ltd
Current assignee: Delta Engineering Holdings Ltd
Priority date: 1991-05-03
Filing date: 1992-04-28
Publication date: 1992-11-04
Also published as: GB9209138D0

Abstract

A fluid flow control valve, which opens in response to a decrease in fluid (water) pressure at its inlet, comprises a valve chamber (17) having an inlet (15), an outlet (18) and a valve seat (21) therebetween. A diaphragm (32) can engage the valve seat (21) to close the valve. A sub-chamber (22), separated from the valve chamber (17) by the diaphragm, has an outlet that can be uncovered to release pressure therefrom. A Bourdon tube (30) receiving inlet fluid pressure is arranged to uncover the outlet in response to a drop in such pressure below a predetermined value, allowing fluid to escape from the second chamber (22) so that the diaphragm (32) moves off its valve seat to open the valve. A subsequent increase in inlet fluid pressure (to mains pressure) causes the Bourdon tube (30) to seal the sub-chamber outlet again, with fluid bleeding into the sub-chamber and causing the diaphragm (32) to move onto its valve seat to close the valve. The pressure at which the valve opens may be determined by adjustment of a screw-threaded nozzle 29 fitted on the outlet from the sub-chamber (22). The valve is used in a flushing system for a urinal, being opened by drop in inlet water pressure which results from opening of a wash-basin tap. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO VALVES This invention relates to a fluid flow control valve, primarily for use in an automatic flushing system for a urinal.

Many automatic flushing systems used with urinals include a cistern which gradually fills from the mains water supply and, when full, automatically empties into the urinal basins to flush them. The intervals at which the flushing occurs can be adjusted by adjusting the rate of filling of the cistern. However, this type of system operates continually, providing the timed flushes irrespective of whether the urinals are actually being used. Accordingly, a great deal of water is wasted.

The object of the invention is to provide a fluid flow control valve in an efficient form, and which is particularly adapted for an automatic flushing system for urinals to reduce water wastage.

According to the invention a fluid flow control valve comprises a valve chamber connecting an inlet for a source of fluid and an outlet, a control member movable between respective first and second positions in which the outlet is open and closed with respect to the inlet, a sub-chamber in communication, in use, with said source of fluid by way of a bleed hole and means arranged for controlling the pressure in the sub-chamber in accordance with the pressure of the fluid at the inlet, in use, so that a variation in the pressure of the fluid at the inlet can cause movement of the control member from one of its first and second positions to the other.

Preferably the means for controlling the pressure in the sub-chamber opens or closes an outlet therefrom.

Conveniently said means is an elongated yieldably deformably hollow tuber for example a Bourdon tuber having one end open and in communication with said inlet for receiving therein the inlet pressure of the fluid entering the valve and its other end closed the tube carrying a seal to close said sub-chamber outlet when the tube is sufficiently deformed by said inlet pressure being at or above a predetermined value.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view through a control valve of the invention shown in its closed position, and Figure 2 is a similar view with the valve in its open position, but with parts of the valve modified to an alternative form.

The drawings show a fluid flow control valve of the present invention, this valve being primarily intended for use with an automatic flushing cistern for a urinal, and is thus primarily intended for use to control the flow of water therethrough. As will be more fully described hereinafter, it is intended that the valve should be arranged relative to a main water supply pipe downstream of water using facilities such as a wash-hand basin and a ball-cock controlled cistern. The automatic flushing system includes one or more cisterns for a urinal, with the valve of the invention being arranged at the water inlet of each cistern, which has syphoning means for emptying it. In use, the valve will only open when the wash-hand basin is used or when the cistern empties upon flushing of its associated lavatory, as a result of a consequential decrease in water pressure at the valve inlet.

The valve comprises a main body 10 which is of generally cylindrical configuration, having at its one open end external screw threads 11. A generally cylindrical end plate 12 has an annular, radially directed external flange 13, which abuts the axially directed annular end of the body 10 at which the screw threads 11 are formed, there being a retaining nut 14 engaged on the threads 11 so as securely to retain the plate 12 onto the body 10. The body 10, plate 12 and nut 14 can all conveniently be formed of a suitable plastics material.

The end of the main body 10 remote from the plate 12 is in the form of an open ended generally elongated tubular part, which forms an inlet 15, the periphery of the open end of the inlet 15 being screw threaded at 16 for connection of the valve at a cistern as will later be described. The inlet 15 leads to a valve chamber 17 from which an outlet 18 is formed, at right angles to the inlet 15. A wall 19 of the outlet extends into the body 10 and with a further short inward extension wall 20, forms an annular valve seat 21 facing the end plate 12.

The plate 12 defines a sub-chamber 22 of the valve and is formed with an outlet passage 23 which leads to its periphery, where an open end of a tube 24 is sealingly connected. The tube 24 is, at its other open end, sealingly connected to a passage 25 in an external, radial flange 26 of the body 10. The passage 25 extends through an extension part 27 of the flange 26, the part 27 being externally threaded at 28 for engagement with an adjustable nozzle 29.

The part of the body which forms the inlet 15 has a radial opening through it at a position upstream of the valve chamber 17, and screw threadedly engaged in this hole is an end of a pressure sensing device. Although this pressure sensing means may take various forms, it is shown in the illustrated embodiment as an elongated yieldably deformably hollow tube 30 which is formed into a generally part-circular shape apart from a short straight portion extending radially out from the body 10.

The end of the tube 30 is closed and a rubber seal 31 is affixed to the outside of the tube adjacent this closed end. As can be seen from the drawings, this seal is disposed close to the open end of the nozzle 29, so that the nozzle can be opened and closed by variations of pressure in the tube 30 resulting from the corresponding pressure variations of the water in the inlet 15 upstream of the valve chamber 17, as will be described. The tube 30 is commonly known as a Bourdon tube, but as mentioned above any suitable pressure sensitive device could be used to open and close the end of the nozzle 29 in response to variation in the pressure of the water in the inlet 15.

The valve chamber 17 is separated from the subchamber 22 by means of a control member in the form of a circular diaphragm 32, normally of rubber. The diaphragm is formed around its periphery as a circular-section annulus 33, which is firmly held in an annular recess formed between the end plate 12 and main body 10, the plate being firmly held on the body by the means of the nut 14 as previously disclosed. The diaphragm 32 has a resilient annular portion 34 and a flat, or generally flat, central portion 35 which is arranged over and around the valve seat 21. As will thus be appreciated from Figures 1 and 2, this central portion 35 of the diaphragm can, by suitable flexing of the annular portion 34, move towards and into engagement with the valve seat 21 or away from and out of engagement with said seat.

Figure 1 shows the portion 35 engaged on the seat with the outlet thus closed, whilst Figure 2 shows the portion 35 lifted off the valve seat so that there is communication between the inlet and the outlet.

The valve has a bleed hole 36 between the valve chamber 17 and the sub-chamber 22, this hole being defined by an aperture in the central portion 35 of the diaphragm 32. A specially formed metering pin 37 is carried by the wall 20, the metering pin 37 being tapered so as to determine the dimensions of the annular passage which defines the bleed hole. The direction of taper is such that flow of water through the bleed hole from the valve chamber 17 to the sub-chamber 22 reduces as the diaphragm moves from its fully open to its fully closed position. This arrangement 'cushions' the closure of the diaphragm, to overcome noise on seating, and the metering pin also ensures that any particles which may be present in the water are unable to block the bleed hole 36. The pin need not be tapered, resulting in the sub-chamber filling more slowly. The pin may in fact be omitted, although, as mentioned, it does effect cleaning of the hole 36 and said cushioning. However, instead a filter can be provided in the inlet to remove blocking particles.

Operation of the flow control valve will now be described.

As already mentioned it is intended that the valve should replace the conventional type of drip feed valve which is presently found in cisterns of an automatic flushing system, where the drip feed provided by the valve periodically fills the cistern which then empties by syphon action to flush a urinal. Thus fitting of the valve merely involves removal of the drip feed valve and a screwing onto the inlet pipe at the cistern by means of the screw threads 16. It is unnecessary, as with other known water saving flow control devices, to break into the main water supply line.

Once fitted the valve will normally operate as shown in Figure 1 with water entering the inlet 15 being at normal mains pressure. As a result the Bourdon tube is caused to deform generally upwardly at its closed end so that the open end of the nozzle 29 is closed. It will be appreciated that as this nozzle is axially adjustable on the extension part 27, the pressure required to close the nozzle 29 can be predetermined merely by rotation of the nozzle to a position where it is closed by the seal 31. Clearly, adjusting the nozzle outwardly on part 27 will mean that water pressure will have to drop by an increased amount before the Bourdon tube moves clear of and thus opens, the nozzle, and vice versa.

With the nozzle 29 closed, water flows from the inlet into the valve chamber 17 where it can pass in a restricted manner through the bleed hole 36 into the subchamber 22. The build up of water in sub-chamber 22, the outlet 23 of which is closed by the closing of the nozzle 29, results in a build up of pressure holding the diaphragm 32 against the valve seat 21, thereby preventing water flowing from the inlet to the outlet.

In this closed position it will be appreciated that the area of the diaphragm on which the water in sub-chamber 22 is acting is significantly larger than the area against which the water in the valve chamber 17 can act.

Thus as long as the sub-chamber 22 is sealed by the closure of the outlet 23 and tube 24, the diaphragm is in its closed position on the valve seat 21 and no water passes out of the outlet 18. Accordingly, as long as mains water pressure is transmitted to the Bourdon tube 30, the valve remains closed with no filling of the cistern associated with the valve.

If however the pressure of the water entering the inlet 15 falls below the predetermined value set by the adjustment of the nozzle 29, the tube 30 will be less pressurised and will deform generally downwardly at its end, thereby releasing the seal 31 from the end of the nozzle 29. Such a reduction in water pressure at the inlet 15 would be the result of the usage of, for example, one or more wash-hand basins or lavatories which are fed by mains water upstream of the flow control valve at the cistern of the urinal.Since, in practise, the use of the basins and lavatories will be roughly in proportion to the use of the urinals, opening of this flow control valve each time there is a reduction in the water pressure at the inlet 15 should result in sufficiently frequent flushings of the urinals without such flushings automatically taking place every time the cistern fills, regardless of whether or not the urinals have been used.

Once the reduction in water pressure at the inlet 15 has resulted in the opening of the nozzle 29, the pressure in the sub-chamber 22 will fall since the outlet passage 23, tube 24 and passage 25 are now communicated with atmospheric pressure, which is lower than that of the inlet water pressure. Accordingly, the pressure on the inlet side of the diaphragm forces the diaphragm upwardly off its valve seat 21, thereby opening communication from the inlet 15 to the outlet 18 with a result that water flows into the cistern and may on a single opening of the valve or on several openings, fill so that water is fed by syphon action to the urinal.

Water flows out of the nozzle 29 as the sub-chamber contracts in size. As soon as the mains water pressure at the inlet 15 increases to its normal value, the tube 30 will again be deformed so that the seal 31 closes the outlet of the nozzle 29, with the result that water now passing into the sub-chamber 22 through the bleed hole 36 will again pressurise the sub-chamber 22 so that the diaphragm 32 will immediately move onto its valve seat 21 and cut off flow through the outlet 18 as the valve closes. Once the inlet pressure returns to normal, the closing of the valve is instantaneous.

Accordingly, automatic flushing of the urinal does not occur at set predetermined intervals, but is related to the use of associated hand-wash basins and lavatories, so that as a result there is a considerable saving in water.

As mentioned, various alternative pressure sensitive means can be used instead of the tube 30, for example a piston or bellows arrangement. Instead of the provision of the tube 24, it would in fact be possible to form a passageway within the body of the valve which extends from the end of the passage 23 to the nozzle 29 which could be disposed on the exterior of the body without the need for the flange 26. Alternatively the tube 24 could be taken upwardly from its nozzle end through a lower part of the body and then through an aperture in the periphery of the diaphragm 32 and into the sub-chamber 22. Further possible changes from the arrangement shown are the positioning of the Bourdon tube circumferentially around the body 10, and the provision of the nozzle on the end of the Bourdon tube with adjustment by means of a separate screw rather than by threads 28.If necessary the flow of water could be restricted downstream of the position at which the pressure sensing means are connected to the body 10.

Figure 2 illustrates an alternative form of valve in which a flow controller is incorporated. Firstly, in order to accommodate the flow controller, the passage 23 is omitted, the end of the tube merely extending downwardly through the end plate 12 to communicate with the sub-chamber 22 at a position away from its centre, The walls 19 and 20 are now provided, at a position just below the valve seat 21, with an annular flange 38 having a relatively small, central circular opening 39, which acts as a restrictor. From the centre of the bottom of the diaphragm projects a generally needle-like, tapered projection 40 for greater or lesser filling of the opening 39 between the open and closed diaphragm positions.The projection 40 can be of rubber and integral with the remainder of the diaphragm, or it can be a separate component, for example of plastics material, fixed through an opening in the centre of the diaphragm. The projection 40 and opening 39 are relatively so sized that with the diaphragm on its seat 21 the projection does not sealingly close the opening.

Screw-threadedly engaged in an opening in the centre of the end plate 12 is a manual adjustment member 41 which has at its inner end an enlarged head 42 for bearing on the upper surface of the diaphragm in line with the projection 40. Accordingly rotation of an outer knurled or splined knob 43 of the member 41 forces the head 42 onto or away from the diaphragm to move it relatively to its seat and thus to move the projection relatively to the opening 39. Thus the member can be adjusted to control flow through the valve in its open state, since the more the projection closes the opening 39, the less the flow from the valve inlet to its outlet, and vice versa. The head can thus act as a stop.

Pressing onto the centre of the diaphragm by use of the member 41 does not alone effect suitable control as the water pressure tends to raise the peripheral part of the diaphragm. Accordingly the restrictor formed by flange 38 and projection 40 is provided so that with the member 41 flow control can effectively be adjusted.

The valve of the invention is particularly advantageous in operation to effect a saving of water and is also convenient in being of relatively simple construction and being very easily fitted in a cistern in place of the conventional drip feed valve, thus as mentioned above, obviating the need to break into the mains water supply line.

Claims

1. A fluid flow control valve comprising a valve chamber connecting an inlet for a source of fluid and an outlet, a control member movable between respective first and second positions in which the outlet is open and closed with respect to the inlet, a sub-chamber in communication, in use, with said the source of fluid by way of a bleed hole and means arranged for controlling the pressure in the sub-chamber in accordance with the pressure of the fluid at the inlet, in use, so that a variation in the pressure of the fluid at the inlet can cause movement of the control member from one of its first and second positions to the other.

2. A valve as claimed in Claim 1, wherein the means for controlling the pressure in the sub-chamber opens or closes an outlet therefrom.

3. A valve as claimed in Claim 1 or Claim 2, wherein the means for controlling the pressure in the sub-chamber is an elongated yieldably deformable hollow tube having one end open and in communication with said inlet for receiving therein the inlet pressure of the fluid entering the valve, in use, and its other end closed, the tube carrying a seal to close said sub-chamber outlet when the tube is sufficiently deformed by said inlet pressure being at or above a predetermined value.

4. A valve as claimed in claim 3, wherein means are provided at said sub-chamber outlet for varying said predetermined value.

5. A valve as claimed in Claim 4, wherein said means at said sub-chamber outlet is an adjustable nozzle.

6. A valve as claimed in any one of Claims 3 to 5, wherein said tube is a Bourdon tube.

7. A valve as claimed in any one of the preceding claims wherein the bleed hole is formed in said control member.

8. A valve as claimed in Claim 7, wherein a pin fixed relative to the control member extends into said bleed hole.

9. A valve as claimed in Claim 8, wherein said pin is tapered so that fluid flow through said bleed hole is more restricted as said control member moves, in use, from its first to its second position.

10. A valve as claimed in any one of the preceding claims, wherein the control member is a diaphragm.

11. A valve as claimed in Claim 10, wherein the diaphragm has a flat or generally flat central portion which engages on a valve seat of said valve chamber in said second position of the control member.

12. A valve as claimed in Claim 10 or Claim 11, wherein a restrictor is disposed in the path along which fluid flows from the inlet to the outlet, in use, when the control member moves off said valve seat.

13. A valve as claimed in Claim 12, wherein the restrictor is defined by an opening which is smaller than that of the valve seat and disposed immediately downstream thereof, the diaphragm having a tapered projection extending from one side thereof and being arranged to extend into said opening when said diaphragm is in its second position, and also during at least part of its movement from its .second position to its first position, when the rate of fluid flow through the restrictor varies.

14. A valve as claimed in Claim 13, wherein said taper of the projection is such that fluid flow through the restrictor increases as the diaphragm moves towards its first position.

15. A valve as claimed in Claim 13 or Claim 14, wherein there is provided an adjustable stop for controlling the movement of the diaphragm from its second position towards its first position by setting said first position and thus the maximum flow rate through the restrictor.

16. A fluid flow control valve substantially as hereinbefore described, with reference to, and as shown in Figure 1 or Figure 2 of the accompanying drawings.