GB2280489A

GB2280489A - A non-return valve

Info

Publication number: GB2280489A
Application number: GB9315733A
Authority: GB
Inventors: Hamish A M Pitt
Original assignee: Valeo Wiper Systems Ltd
Current assignee: Valeo Wiper Systems Ltd
Priority date: 1993-07-29
Filing date: 1993-07-29
Publication date: 1995-02-01
Anticipated expiration: 2013-07-29
Also published as: GB9315733D0; GB2280489B

Abstract

A non-return valve, e.g. for a windscreen washer device, comprises a tubular member (10) incorporating a tubular spigot (15) with an aperture (16) in its wall; a transverse partition (17) intercepting the aperture and separating the upstream (14) and downstream (19) portions of the tubular member; and a distensible sleeve (18) fitting closely over the spigot (15) and a chamber (21) surrounding the distensible sleeve (18) and in communication with the downstream portion (19), so that excess pressure in the upstream portion (14) can distend the sleeve (18) to allow passage of liquid, but excess pressure in the downstream portion (19) is applied to both sides of the sleeve (18) and cannot distend it to allow reverse flow. <IMAGE>

Description

A NON-RETURN VALVE This invention relates to non-return valves, particularly though not exclusively for use in vehicle windscreen washer devices.

It is known to provide such a device with a check valve comprising a valve body with longitudinal and transverse bores and a flexible (i.e. distensible) sleeve fitted closely over the valve body so as to be capable of distending under pressure of fluid supplied to the longitudinal bore and thereby to allow fluid to pass to the washer nozzles. In general, this arrangement helps to retain a supply of fluid adjacent to the nozzles for use at the next time of operation, but fluid may flow in reverse through the valve body, so emptying the piping adjacent the nozzles and causing delay in response next time the washer is operated.

An object of the invention is to provide a simple and effective non-return valve, which can overcome this problem.

According to the present invention, a non-return valve, e.g. for a windscreen washer device, comprises a tubular member having an upstream portion adapted to communicate with a source of fluid under pressure, an aperture through a wall of the tubular member, a distensible sleeve fitting closely over said wall so as to close the aperture, and a transverse partition which extends across the interior passage of the tubular member in way of the aperture and which, in conjunction with the distensible sleeve, normally closes off the upstream portion from a downstream portion of the tubular member, wherein the said downstream portion includes a chamber surrounding the distensible sleeve, so that excess pressure in the upstream portion as compared to the downstream portion can cause distension of the distensible sleeve and allow passage of fluid from the upstream to the downstream portion, whereas pressure in the downstream portion is applied to both sides of the distensible sleeve and excess pressure in the downstream portion cannot distend the sleeve to allow reverse flow of fluid.

The tubular member may comprise two parts secured together in fluid-tight manner, the first part comprising a tubular spigot which is provided with the aperture and the transverse partition and which is surrounded by the distensible sleeve. Preferably the first part of the tubular member also comprises a second tubular spigot coaxial with and surrounding the first-mentioned tubular spigot over at least a part of its length, and radially spaced therefrom by a distance exceeding the thickness of the distensible sleeve, so as to define at least a part of the chamber between the second spigot and the distensible sleeve.

The second part of the tubular member may have a tubular spigot engaging over an end portion of the second tubular spigot of the first part of the tubular member. Interengaging projections and recesses are preferably provided on the tubular spigot of the second part and the second tubular spigot of the first part of the tubular member.

A specific embodiment of the invention will now be described by way of example and with reference to the accompanying drawing, which is a diagrammatic longitudinal section through a non-return valve according to the invention.

In the embodiment illustrated, the non-return valve comprises a tubular member generally indicated at 10 and formed of two parts 11, 12 secured together in a fluid-tight manner. The first part 11 includes the upstream portion 14 of the tubular member and is adapted to communicate with a source of fluid under pressure, such as a pump (not shown) which draws windscreen washing liquid from a tank and delivers it through the non-return valve to a windscreen washing nozzle or nozzles.

The first part 11 of the tubular member 10 comprises a first tubular spigot 15 which is provided with at least one aperture 16 (two as shown) extending through its wall and with a transverse partition 17 which extends across the interior passage of the spigot 15 in way of the aperture or apertures 16. A distensible sleeve 18, e.g. of rubber, is fitted closely over the wall of the spigot 15 so as to close the aperture or apertures 16. In conjunction with the partition 17, the sleeve 18 normally closes off the upstream portion 14 from the downstream portion 19 of the tubular member, which is contained within its second part 12.

The first part 11 of the tubular member 10 comprises a second tubular spigot 20 coaxial with the first tubular spigot 15 and surrounding it over at least a part of its length. The radial spacing between the spigots 15, 20 exceeds the thickness of the distensible sleeve 18 so as to define an annular chamber 21 between the second spigot 20 and the sleeve 18. The chamber 21 is in free coummunication with the interior of the second part 12 of the tubular member, i.e. its downstream portion 19.

The two parts 11, 12 of the tubular member 10 are secured together by means of a tubular spigot 22 on the second part 12 engaging over a reduced end portion 23 of the second spigot 20 of the first part 11. Interengaging projections and recesses may be provided as shown on the respective spigots 20, 22 to enable them to be snap-fitted together.

With this arrangement, excess pressure of liquid in the upstream portion 14 as compared with the downstream portion 19, e.g. on operation of the windscreen washer pump, causes distension of the distensible sleeve 18 and thus allows passage of liquid around the partition 17 as shown by the arrows to the downstream portion 19, and e.g. to the washer nozzles. On the other hand, pressure in the downstream portion 19 is applied to both sides of the distensible sleeve 18, so that if the pressure in the downstream portion 19 were to exceed the pressure in the upstream portion 14, e.g. when the pump is not operating, the sleeve 18 could not be distended to allow reverse flow of liquid. The device thus acts as a simple and effective non-return valve to prevent flow of liquid back from the washer nozzles.

Claims

CLAIMS:

1. A non-return valve, e.g. for a windscreen washer device, comprising a tubular member having an upstream portion adapted to communicate with a source of fluid under pressure, an aperture through a wall of the tubular member, a distensible sleeve fitting closely over said wall so as to close the aperture, and a transverse partition which extends across the interior passage of the tubular member in way of the aperture and which, in conjunction with the distensible sleeve, normally closes off the upstream portion from a downstream portion of the tubular member, wherein the said downstream portion includes a chamber surrounding the distensible sleeve, so that excess pressure in the upstream portion as compared to the downstream portion can cause distension of the distensible sleeve and allow passage of fluid from the upstream to the downstream portion whereas pressure in the downstream portion is applied to both sides of the distensible sleeve and excess pressure in the downstream portion cannot distend the sleeve to allow reverse flow of fluid.

2. A non-return valve according to Claim 1, wherein the tubular member comprises two parts secured together in fluidtight manner, the first part comprising a tubular spigot which is provided with the aperture and the transverse partition and which is surrounded by the distensible sleeve.

3. A non-return valve according to Claim 2, wherein the first part of the tubular member also comprises a second tubular spigot coaxial with and surrounding the first-mentioned tubular spigot over at least a part of its length, and radially spaced therefrom by a distance exceeding the thickness of the distensible sleeve, so as to define at least a part of the chamber between the second spigot and the distensible sleeve.

4. A non-return valve according to Claim 3, wherein the second part of the tubular member has a tubular spigot engaging over an end portion of the second tubular spigot of the first part of the tubular member.

5. A non-return valve according to Claim 4, wherein interengaging projections and recesses are provided on the tubular spigot of the second part and the second tubular spigot of the first part of the tubular member.

6. A non-return valve for a windscreen washer device, substantially as hereinbefore described with reference to the accompanying drawing.