GB2319586A

GB2319586A - One-way valve

Info

Publication number: GB2319586A
Application number: GB9624124A
Authority: GB
Inventors: Bernard Renzo; Joel Breheret
Original assignee: Draftex Industries Ltd
Current assignee: Laird Holdings Ltd
Priority date: 1996-11-20
Filing date: 1996-11-20
Publication date: 1998-05-27
Also published as: GB9624124D0

Abstract

A one-way valve comprising a tubular valve chamber (30A) connected between pipe (20A) and enclosure (6) includes a movable thermoplastics valve member (40A). Valve member (40A) comprises closure plate (42A) carrying three guiding legs (44A,46A,48A) positioned at 60 degree intervals around the periphery of closure plate (42A) and extending to a position short of disk (34A) at the opposite end of the valve chamber (30A). The distal ends of legs (44A,46A,48A) are interconnected by a tubular support (50A). Legs (44A,46A,48A) and support (50A) control the attitude of plate (42A) in use. When pressure within enclosure (6) is higher than in pipe (20A) closure plate (42A) blocks connection between pipe (20A) and enclosure (6). When the pressure difference is opposite, closure plate (42A) moves right until tubular support (50A) abuts disk (34A). Fluid can now flow from pipe (20A), around the periphery of plate (42A), through the interior of valve member (40A) and into enclosure (6) through an aperture (38A) in disk (34A). If valve member (40A) is inserted with the opposite axial orientation, the one-way operation of the valve is reversed.

Description

ONE-WAY VALVES The invention relates to one-way valves. In a particular application to be described in more detail below, by way of example only, one-way valves embodying the invention are incorporated in priming pumps such as manually operable priming pumps for priming the fuel systems of motor vehicle engines.

However, valves embodying the invention can be used in many other applications.

According to the invention, there is provided a one-way valve for controlling the flow of fluid along a path, comprising a valve chamber having spaced first and second openings and for connection in series with the path via the openings, and a valve member having limited movement within the valve chamber in directions between the two openings, the valve member comprising blocking means which blocks the first opening when the valve member is moved to one end of its limited movement in response to a pressure difference of predetermined sense applied across the blocking means and guiding means extending from the blocking means in the direction towards the second opening for controlling the attitude of the blocking means as the valve member moves towards the other end of its limited movement in response to a pressure difference of the opposite sense applied across the blocking means whereby fluid flow into the valve chamber through the first opening can pass around the blocking means and thence through the second opening.

According to the invention, there is further provided a one-way valve for controlling the flow of fluid along a path, comprising a valve housing for location within the path and defining a generally tubular valve chamber having first and second openings connected to upstream and downstream regions of the path respectively, and a valve member within the valve chamber and movable therein between the two openings, the valve member comprising blocking means having a cross-sectional area which is greater than that of the first opening but less than that of the valve chamber and movable in response to a pressure difference of predetermined sense applied across it into a position in which it blocks the first opening so as to block movement of fluid along the path and movable in response to a pressure difference applied across it in the opposite sense to move towards the other opening so as to unblock the first opening and to allow fluid flow through that opening, around the blocking means and thence through the second opening, the blocking means carrying guiding means extending longitudinally of the tubular chamber towards the second opening for substantially maintaining the attitude of the blocking means during movement of the valve member.

Manually operable fluid pumps embodying the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a cross-section through one of the pumps; Figure 2 is a cross-section on the line II-II of Figure 1 but showing the pump in the deflated condition; Figure 3 is an enlarged cross-section through a one-way valve used in the pump of Figure 1; Figure 4 is an enlarged cross-section through another one-way valve used in the pump of Figure 1; Figure 5 is a section on the line V-V of Figure 3; Figure 6 is a view corresponding to part of the valve shown in Figure 3 but showing a modification; and Figure 7 corresponds to Figure 6 but shows a further modification.

The pump shown in Figure 1 is designed for connection in the fuel pipe leading from the fuel tank to the engine in a motor vehicle.

The fuel may be diesel fuel or petrol. The purpose of the pump is for manually priming the fuel supply system when the tank has been replenished after becoming empty. In certain types of fuel supply system (such as for diesel engines, for example), the fuel supply pipe must be primed (that is, filled with fuel) in the event that all the fuel in the fuel tank is used. If this is not done, the normal engine fuel pump will not be able to draw fuel into the engine, and it will not be possible to operate the engine. The priming pump to be described is placed in an easily accessible position (e.g. in the engine compartment) and can be manually operated to prime the fuel supply system as and when necessary.

As shown in Figure 1, the priming pump comprises a membrane 5 whose external shape is similar to that of a rugby ball and defines a hollow enclosure 6 with narrowed necks 8 and 10.

According to a feature of the pump, the membrane 5 is made of a thermoplastic elastomer with a thickness of up to about 0.8mm. Each neck portion 8,10 is connected to a respective fuel pipe 12,14 by a respective valve unit 16A,16B. The material of the neck portions 8,10 has a minimum thickness of lmm. Fuel pipe 12 is connected to the fuel reservoir or fuel tank of the vehicle. Fuel pipe 14 is connected to the vehicle engine. The pump is thus interposed in series with the fuel supply system for the vehicle. The pump described is advantageously produced by blow-extrusion or blow-injection.

The valve units 16A,16B are moulded of thermoplastic elastomeric material. Valve unit 16A,16B comprises a small diameter hollow connector portion 18A,18B which is externally serrated and has a through bore 20A,20B leading to an integral large diameter externally serrated valve housing 22A,22B. Each valve housing 22A,22B incorporates a one-way fluid valve (to be described in more detail below) which permits fuel to flow in the direction of the arrows A and B shown in Figure 1 but not in the reverse direction. A flange 24A,24B is integrally positioned between the connector and valve parts.

The internal diameter of the neck portions 8,10 of the membrane 5 is arranged to be less than the external diameter of the valve portions 22A and 22B. In order to fit the valve units 16A,16B in position in the membrane 5, the membrane is heated to a temperature between 30 degrees and 80 degrees C. The valve housings 22A,22B are then force-fitted into the neck portions 8,10. As the material of the membrane 5 cools, a very tight sealing and gripping fit between each valve housing 22A,22B and the respective neck portion 8,10 of the membrane 5 is achieved.

The fuel pipes 12,14 can then be force-fitted onto the respective connector portions 18A,18B.

In operation, normal fluid flow of the fuel to the engine passes through valve unit 16A in the direction of arrow A, through the hollow interior 6 of the membrane 5, and thence through valve unit 16B in the direction of the arrow B and via the pipe 14 to the engine. During this process, the fuel is drawn by the normal engine fuel pump (not shown). If the fuel tank becomes empty, the fuel supply system, including the pipes 12 and 14 and the interior 6 within membrane 5, will become dry of fuel. Even when the fuel tank has been replenished, the normal fuel pump of the vehicle will not be able to draw fuel into the engine - because the fuel supply system is empty of fuel. It is first necessary to re-fill (or "prime") the fuel supply system with fuel. This process is carried out manually by repeatedly squeezing the membrane 5, allowing it to relax under its normal resilience between each squeeze. During each squeeze, the membrane 5 is substantially collapsed and any fuel within the hollow interior 6 is expelled through valve unit 16B in the direction of arrow B, that is, towards the engine. When the membrane is allowed to relax to the form shown in Figure 1, the expansion of the hollow interior 6 draws fuel into the hollow interior through the valve unit 16A in the direction of arrow A; fuel cannot be drawn into the hollow interior 6 from the pipe 14 because of the oneway valve in the valve housing 22B. In response to the next squeeze of the membrane 5, the fuel drawn into the hollow interior 6 is thus expelled through valve housing 22B into the fuel pipe 14 and thence to the engine. This process is continued until the fuel supply system is fully primed and the normal engine fuel pump can operate in the usual way to supply the engine with fuel.

Under certain circumstances, the pressure within the fuel supply system can become reduced below atmospheric pressure, by an amount of the order of 0.5 bar. This depression will cause the membrane 5 to collapse partially. However, the construction and physical characteristics of the thermoplastics material are such that, in the event of such a pressure reduction within the hollow interior 6, the membrane 5 collapses in the manner shown in Figure 2, thus always leaving a continuous through passage 20 which, although of reduced cross-sectional area, is nevertheless sufficient to allow fuel to pass through the hollow interior 6, so that the engine can continue to be supplied with fuel.

The pump described is advantageous over known priming pumps which have a membrane made of rubber. Such rubber membranes have to be relatively thick in order to provide the necessary strength and may also need to be provided with reinforcing circumferential and longitudinal ribs on the external surface in order to provide it with sufficient rigidity. Such a rubber membrane is relatively heavy and has to be produced by a moulding operation, requiring forcible removal from the mould which in turn produces the risk of degrading the mechanical characteristics of the membrane. There is thus a risk of rupture of the membrane during use. Such rupture would clearly have serious consequences.

Furthermore, in the event of a reduction in pressure within the fuel pipe, total collapse of the rubber membrane can occur, which would completely close the fuel supply to the engine, again with potentially serious consequences.

The one-way valves incorporated in the valve housings 22A and 22B will now be described with reference to Figures 3 - 5.

Figure 3 shows the valve unit 16A. Its valve housing 22A defines a generally hollow valve space or chamber 30A which is of generally cylindrical shape. At one axial end it is connected to the through bore 20A of the connector portion 18A and at the opposite axial end it is open to the hollow interior 6 of the membrane 5. At this end of the valve chamber 30A, a circumferential shoulder 32A is formed against which is seated a retaining disk 34A having an axially directed flange 36A. The disk 34A has a central hole 38A. The disk 34A is secured in position against the shoulder 32A in any suitable way, such as by adhesive.

The valve unit 16A also includes a movable valve member 40A.

This comprises a circular plate 42A which is connected by three (for example) legs 44A,46A,48A (see Figure 5) which extend in parallel directions, with their distal ends being integrally connected by a tubular part 50A, the axial length of which is substantially less than its diameter. The diameter of the plate 42A, and the thickness of the legs 44A,46A,48A, are such that there is clearance between the internal surface of the valve chamber 30A and the legs 44A,46A and 48A and around the outside of the tubular part 50A. The valve member 40A can therefore slide freely within the valve chamber 30A between two limiting positions. In one limiting position (shown in Figure 3), the plate 42A abuts against the axial face of the valve chamber 30A where it communicates with the through bore 20A. In the other limiting position, the valve member 40A has moved to the right (as viewed in Figure 3) so that the tubular part 50A abuts against the retaining disk 34A.

Figure 4 illustrates the one-way valve incorporated in the valve unit 16B. Items in Figure 4 corresponding to those in Figure 3 are similarly referenced, except for the use of the suffix "B" instead of "A".

It will be noted that, in the one-way valve of Figure 4, the movable valve member 40B is mounted so as to be oppositely oriented compared with Figure 3. Thus, the movable valve member 28B in Figure 4 is mounted so that its valve plate 40B abuts against the retaining disk 34B, while the open-ended tube 50B faces the end of the valve space 3OB connected to the through bore 20B.

The operation of the one-way valves will now be described.

When the membrane 5 is manually squeezed, to start the priming operation already described, pressure is increased within the hollow interior 6. Within the one-way valve in unit 16A, this increased pressure is applied through the hole 38A against the plate 42A and presses the plate against the end face of the valve chamber 30A. The plate 42A therefore closes off the through bore 20A. There is therefore no connection between the hollow interior 6 and the through bore 20A. However, the increased pressure within the hollow interior 6 will be applied to the plate 40B of the one-way valve in unit 16B through the hole 38B in the disk 34B. The movable valve member 40B will therefore move to the right (as viewed in Figure 4). Fuel under pressure within the hollow interior 6 can thus pass from the hollow interior and into the through bore 20B. The fuel passes through the hole 38B and around the periphery of the plate 40B and thence through the tube 50B to the through bore 20B and thence to the vehicle engine.

When manual pressure on the membrane 5 is released, so that the membrane resiles, there is a reduction in pressure within the hollow interior 6. Plate 40B is drawn into contact with the disk 34B and closes off the hole 38B. The hollow interior 6 is thus disconnected from the through bore 20B. At the same time, however, the pressure reduction within the hollow interior 6 causes the movable valve member 40A of the valve 28A to move to the right as viewed in Figure 3. Fuel can now be drawn into the hollow interior 6 via the through bore 20A. The fuel passes around the periphery of the plate 42A and into the hollow interior 6 through the tube 50A and the hole 38A.

The one-way valves are advantageously made of plastics or thermoplastics material such as by injection moulding. Each valve has only three parts, comprising the externally serrated housing 22A,22B, the retaining disk 34A,34B and the movable valve member 40A,40B. The same three parts can be assembled so as either to produce an "entry/no exit" valve (Figure 3) or an "exit/no entry" valve (Figure 4).

As described, the movable valve members 40A,40B have three supporting legs 44A (or 44B), 46A (or 46B), and 48A (or 48B).

However, this number of legs may be altered. The supporting tube 50A,50B is not essential, though desirable for ensuring axial alignment of the legs.

Figures 6 and 7 show alternative means for securing the retaining disk 34A,34B in position. In Figure 6, the retaining disk is located in a slot 60. In Figure 7, the flange 36 is extended to form a radially directed shoulder 62 which is fixed in position by adhesive 64 or other suitable means.

Other modifications may also be made.

Claims

1. A one-way valve for controlling the flow of fluid along a path, comprising a valve chamber having spaced first and second openings and for connection in series with the path via the openings, and a valve member having limited movement within the valve chamber in directions between the two openings, the valve member comprising blocking means which blocks the first opening when the valve member is moved to one end of its limited movement in response to a pressure difference of predetermined sense applied across the blocking means and guiding means extending from the blocking means in the direction towards the second opening for controlling the attitude of the blocking means as the valve member moves towards the other end of its limited movement in response to a pressure difference of the opposite sense applied across the blocking means whereby fluid flow into the valve chamber through the first opening can pass around the blocking means and thence through the second opening.

2. A one-way valve according to claim 1, in which the pressure difference of the predetermined sense is created by a pressure increase applied to the valve chamber through the second opening and the pressure difference of the opposite sense is created by a pressure decrease applied to the valve chamber through the second opening.

3. A one-way valve according to claim 1, in which the pressure difference of the predetermined sense is created by a pressure decrease applied to the valve chamber through the second opening and the pressure difference of the opposite sense is created by a pressure increase applied to the valve chamber through the second opening.

4. A one-way valve according to any preceding claim, in which the valve chamber is generally cylindrical and the first and second openings are positioned at its opposite axial ends.

5. A one-way valve according to claim 4, in which the blocking means comprises a member of lesser cross-sectional size than that of the valve chamber, and the guiding means comprises a plurality of guide members extending parallel to each other and in a generally axial direction from the member.

6. A one-way valve according to claim 5, in which the distal ends of the guiding members are interconnected by support means.

7. A one-way valve according to claim 6, in which the support means comprises an open-ended tubular member.

8. A one-way valve according to any preceding claim, in which the valve chamber is defined within a valve housing for insertion in a conduit forming part of the said path.

9. A one-way valve according to any one of claims 1 to 7, in which the valve chamber is defined within a housing, the housing being open-ended to allow insertion of the valve member, and including a separate apertured member which is thereafter placed in position to close off the open end of the housing except for an aperture in the apertured member which defines one of the openings.

10. A one-way valve according to claim 8 or 9, in which the housing is externally serrated to facilitate its securing in the path.

11. A one-way valve according to any preceding claim, in which the path includes a pump.

12. A one-way valve according to claim 11, in which the pump is manually operable.

13. A one-way valve for controlling the flow of fluid along a path, comprising a valve housing for location within the path and defining a generally tubular valve chamber having first and second openings connected to upstream and downstream regions of the path respectively, and a valve member within the valve chamber and movable therein between the two openings, the valve member comprising blocking means having a cross-sectional area which is greater than that of the first opening but less than that of the valve chamber and movable in response to a pressure difference of predetermined sense applied across it into a position in which it blocks the first opening so as to block movement of fluid along the path and movable in response to a pressure difference exerted on it in the opposite sense to move towards the other opening so as to unblock the first opening and to allow fluid flow through that opening, around the blocking means and thence through the second opening, the blocking means carrying guiding means extending longitudinally of the tubular chamber towards the second opening for substantially maintaining the attitude of the blocking means during movement of the valve member.

14. A one-way valve according to claim 13, in which at least one of the ends of the tubular valve chamber is closed off by a closure member having an aperture defining one of the said openings, the closure member being mounted in position after insertion of the valve member into the tubular valve chamber.

15. A one-way valve according to claim 13 or 14, in which the valve chamber is cylindrical and the blocking means is a circular plate, and in which the guiding means comprise a plurality of guiding legs extending parallel to the longitudinal axis of the tubular valve chamber from respective positions spaced around the periphery of the blocking means and extending therefrom to terminate short of the second opening in the valve chamber.

16. A one-way valve according to claim 15, in which the distal ends of the guiding members are attached together by support means to maintain the guiding legs parallel to each other.

17. A one-way valve according to claim 16, in which the support means comprises a ring-shaped member.

18. A one-way valve according to any preceding claim, made from thermoplastics material.

19. A one-way valve, substantially as described with reference to Figures 3 and 5 of the accompanying drawing.

20. A one-way valve, substantially as described with reference to Figure 4 of the accompanying drawing.