GB2326699A

GB2326699A - Self-closing/time delay valve assembly and water supply tap

Info

Publication number: GB2326699A
Application number: GB9815755A
Authority: GB
Inventors: Michael Rice
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-09-07
Filing date: 1995-09-07
Publication date: 1998-12-30
Anticipated expiration: 2015-09-07
Also published as: GB9815755D0; GB2326699B

Description

TITLE: Self-closing/time delay valve assembly and water supply tap DESCRIPTION The present invention relates to a self-closing/time delay valve assembly for a water supply tap and to a self-closing/time delay water supply tap.

Self-closing/time delay water supply taps are being increasingly specified in the interests of water conservancy. One known purpose-designed push-operated self-closing water tap comprises a sleeve which is threaded to fit into a tap body and received slidably within the sleeve is a spindle which is sealed with respect to the bore of the sleeve and which projects from opposite ends of the sleeve. The spindle passes sealingly through a port ring disposed at the lower end of the sleeve and the spindle has an internal bore and spaced axial ports intersecting with the internal bore. In the closed position the water access to the lower inlet port is closed by the port ring seal. On axial displacement of the spindle the inlet port is uncovered and water can enter the port and pass to the other side of the seal via the internal bore in the spindle. The lower end of the spindle carries a lip seal which is received slidably as a close fit in a blind bore except that the wall of the bore has a small chordal flat with a shallow axial groove therealong. On axial displacement of the spindle against a return spring water is displaced from the blind bore past the lip seal and movement in the reverse direction is resisted by a suction effect within the blind bore such that water has to bleed past the lip seal. This is made possible by the groove running down the chordal flat. The arrangement results in delayed closing of the valve. A disadvantage with this lcnown construction resides in the plurality of component parts and difficulties of insuring a satisfactory water shut-off.

Another push-operated self-closing tap which is intended to convert normal screw-operated taps comprises a sleeve adapted to be screwed into the tap body and a valve disposed slidably within the sleeve having sealing means for closing a valve seat at the lower end of the sleeve. The valve is moved against resilient biasing and a seal intermediate opposite ends of the valve stem mates with an internal bore of the sleeve. On axial displacement of the valve in the opening direction water passes through a bore in a flange in the spindle and past a loose rubber washer into a chamber to the trailing side of said seal. Movement in the opposite direction under the spring pressure is resisted as the presence of water on the trailing side of the seal acts on the rubber washer to close off the bore and water can only bleed from the chamber via a bleed bore in the spindle. The size of the bore can be adjusted. The construction is complicated and expensive to manufacture and difficult to assemble. A plurality of O-ring seals are provided to seal the spindle with respect to the sleeve and this creates a large frictional effect making it difficult to the move the valve. In order to overcome friction a stronger return spring is required. The number of component parts used and the number of seals makes the adapter expensive and problematic.

An aim of the invention is to provide a means of controlling movement of the valve member in the closing direction.

Accordingly the invention provides a self-closing/time delay valve assembly for a water supply tap comprising a valve body adapted to fit in a water supply tap body, the valve body having a valve seat around a water inlet passage and receiving an axially slidable valve member having means to close off the water inlet passage in a closed position, the valve is movable against resilient biasing, one end of the valve member extends sealingly from the valve body and carries an actuating plunger which makes sealing engagement the valve body to define an air chamber between the plunger and the valve body from which air is expelled during an opening movement of the valve and wherein the admission of air to the chamber is restricted to control the rate of closing.

This assembly is conveniently used with the afore-described bellows seal, and is further described hereinafter.

By relying on an air chamber to control the rate of closing the performance of the valve is not affected by the build up of limescale which can be a problem with prior art devices in which closing is controlled by water flow to give the desired delayed closing. Advantageously there is an adjustable bleed passage between the chamber and the external air (eg.

atmosphere) by which the rate of air ingress can be adjusted and thereby adjust the rate of closing. The rate at which air is admitted into the chamber may be variable or constant throughout the stroke of the valve, but it is advantageous if the rate is increased just before closing takes place. More particularly, it is advantageous if a rapid pressured equalisation takes place just before closing. This has the effect of accelerating valve closure to cut off the water supply sharply and thereby avoid incomplete closure which could result in a dripping tap. The rapid pressure equalisation can be conveniently achieved by strategic positioning of a port or passageway to breach the sealing arrangement of the plunger with the valve body at a predetermined position in the closing movement. Conveniently this can take the form of a groove cut in the actuating plunger. Conveniently the sealing of the actuating plunger with the valve body is provided by an annular lip seal with the lip inclined to make sealing contact under the influence of the vacuum within said chamber. The actuating plunger may be received in a bore of the valve body, but preferably the actuating plunger comprises a sleeve or bonnet carried by the end of a spindle of the movable valve member which projects from the valve body in sealing contact with the outer periphery of the valve body. The annular sealing element is conveniently mounted on the valve body. Advantageously the bonnet is releasably connectable with the spindle, which connection is sealed.

Advantageously, the sealing of the valve member with respect to the valve body where the end of the valve member extends from the valve body incorporates a low friction seal so as to avoid increasing the resistance to closing. Preferably the sealing means comprises a first part received sealingly on the movable valve member and connected by way of axially flexible portion (eg. axially expandable and compressible) to a second part sealingly engaged with the valve body. Conveniently, the axially flexible portion comprises a bellows portion. Optionally, said first portion includes an annular sealing lip which makes engagement with an internal bore of the valve body. Said annular sealing lip is disposed upstream of the valve seat and carried by the valve member and engageable with the bore in the valve body and defines a chamber within the valve body and upstream of the annular lip seal of said first part. Conveniently said annular lip seal of the sealing means is apertured to allow water past the seal when the spindle is moved to pass water between the leading and trailing sides of the annular lip seal. This gives rise to a damping or smoothing action of the valve.

Another aspect of the invention provides a water supply tap incorporating the above-described self-closing/time delay valve assembly and pneumatic closing control mechanism.

More particularly the water inlet passage is disposed to the lower end of the sleeve and conveniently comprises a cylindrical bore providing a guide surface for a spindle of the valve member. The means for sealing the inlet passage may comprise a suitable valve face to mate with the aforesaid valve seat, but more preferably comprises an O-ring seal or washer.

Conveniently the O-ring seal is received on a reduced diameter portion of the valve spindle and retained thereon by a locking nut threaded onto the end of the valve spindle or other suitable fixing device. Part of the valve spindle is dimensioned to be received in said cylindrical bore of the water inlet passage. Conveniently the spindle has one or more grooves in its periphery and running axially. On opening of the valve the water can pass by way of said one or more grooves into said chamber of the valve body. Conveniently the valve spindle has a flange intermediate its end and resilient biasing comprises a spring acting between a lower end of the valve body and said flange.

An end closure cooperates sealingly with the upper end of the valve body and has the valve spindle extending therethrough. The need for a separate seal between the end cap and the valve spindle is avoided by the provision of the aforesaid axially expandable and contractible portion between said first part of the seal portion and the end seal portion providing the aforesaid sealing engagement between said first part of the end cap and the valve body. As previously mentioned said axially expandable and contractible portion comprises a bellows portion. Thus, in a preferred embodiment, water to the trailing side of the sealing means (relative to the direction of opening of the tap), actually the trailing side of the lip seal, is received in said chamber defined between the sealing element and the bore of the valve body.

The lower end of the valve body chamber is apertured to permit passage of water to the outlet of the tap. The valve body is typically received in the body of the tap by way of a screw threaded connection.

Adapters may be provided to suit different sizes of valve tap body.

The present invention will now be described further, by way of example only, with reference to the accompanying drawing, in which: Figure 1 is a cross-sectional view through a valve assembly and showing part of a valve tap body embodying the invention.

Referring to the drawing, a valve assembly comprises a valve body 101, a bore 103 to the lower end of which forms a water inlet passage and has an annular valve seat 105 to the end thereof. The valve body in the illustrated embodiment has second and third stepped diameter bores 107, 109 respectively. Water outlet passages 111 are provided in the walls of the valve body. A valve spindle 113 is disposed within the valve body and arranged to be axially slidable with respect thereto against resilient biasing of coil spring 115 acting between a shoulder of the valve body at a lower end and a flange 117 carried by a spindle of the valve and disposed intermediate its ends. The spindle is slidably guided within the bore 103 and in the illustrated embodiment the periphery of the spindle has three circumferentially spaced axially extending grooves 118. A lower end of the spindle is of reduced diameter and threaded as at 119 and carries an O-ring seal 121 retained on the threaded portion 119 by a lock nut 123. The water inlet passage is sealed by mating engagement of the O-ring seal 121 with the valve seat 105.

It will be apparent that the figure shows the valve assembly in its fully closed position. An end cap 125 is threaded onto the upper end of the valve body and has a bore through which an upper end 127 of the valve spindle projects. An actuating cap 130 is secured to the valve spindle by any suitable means, conveniently using a circlip washer 128 received in retention groove 127a.

End cap 125 carries an annular lip seal 155 received in a groove 157 of the end cap 125. The annular lip seal makes sealing contact with the inner bore 159 of the actuating cap or bonnet 130. The connection of the spindle 127 to the actuating cap 130 is sealed from the atmosphere conveniently by way of a sealing bezel 130 or alternatively by way of a O- ring between the end of the spindle and the end wall of the actuating cap.

The lowermost end of the actuating cap 130 has at least one axial groove 161 extending from the lower end thereof a prescribed distance and functions as described further hereinafter.

Sealing means is generally indicated at 129, and in the illustrated embodiment comprises a first seal portion 131, an end seal 133 and a flexible bellows portion 135 connecting the first seal portion and the end seal. The first seal is carried sealingly on the valve spindle between flange 117 and a smaller flange 137. The end seal 133 is trapped between the end cap 125 and the end of the valve body 1. By this means water is denied access to the spindle where it passes through the end cap 125.

In the illustrated embodiment the first seal portion 131 is extended to form an annular lip seal 163 which contacts the bore 107 and effectively defines a chamber 139 to the trailing side thereof between the valve body and the remainder of the seal 129. The lip seal incorporates one or more through bores 165 to provide a liquid flow passage between the leading and trailing sides of the lip seal 163. This allows liquid to flow between the two sides of the seal and acts as a damping means.

The end cap 125 incorporates a threaded bore 167 for receiving a threaded bleed screw 169. A chamber 170 is defined within the actuating cap or bonnet 130 sealed from the atmosphere by the lip seal 155, the end cap seal 130 and from the water supply by the seal 129. The bleed screw 169 and its associated bore together with the threaded connection 171 between the end cap 125 and the valve body constitutes a bleed passage controlling the flow of air between the atmosphere and chamber 170.

When the valve assembly is inserted into a tap body shown generally at 141 a sealing washer 143 is trapped between an abutment 145 of the valve body and an abutment 147 of the tap body. The valve body may be directly threaded into the tap body or an intermediate adapter employed such as that shown at 149 in the illustrated embodiment.

In operation of the valve assembly, the force exerted by a spring 115 displaces the valve spindle upwardly so that the seal 121 makes sealing engagement with the valve seat 105. On actuation of the valve by pushing on the cap 130 to displace it axially downwards as viewed in the illustration, water from the supply side is admitted to the grooves 118 and so passes into the chamber within the valve body outwardly of the valve spindle. The water may then pass through ports 111 to be dispensed from the tap outlet.

The movement of the valve spindle axially downwardly causes air to be displaced from the chamber 170 past the lip seal 155 to atmosphere.

Maximum axial movement of the valve spindle is limited by engagement of flange 117 with the abutment surface 107a at the end of bore 107.

On releasing pressure on the actuating cap 130 the spring 115 attempts to urge the valve in the closing direction. However, since the chamber 170 has been evacuated the pressure differential between the chamber 170 and the atmosphere applies a restraining force restricting movement in the return direction. The vacuum draws the lip seal 155 into contact with the bore 159. However, the bleed path comprising the threads 171, bore 167 and bleed valve 169 allows a leakage path from atmosphere to the chamber 170 which gradually equalises the pressure and therefore reduces the resistance to movement under the influence of the spring 115. When the lip seal reaches the edge of groove 161 rapid pressure equalisation occurs and the valve closes quickly.

Because water is non-compressible the presence of water behind the lip seal 163 provides a potential bar to return movement as it forces the lip seal into engagement with the bore 107. This is overcome by providing the ports 165 which allow water past the lip seal whilst providing a damping function. The lip may be eliminated from the first element.

The valve spindle and the valve body and any adapter are conveniently made from plastics material, preferably PTFE, or alternatively may be cast from a suitable metal. It will be noted that according to the invention only two sealing elements are required as part of the valve assembly and the design avoids using O-ring seals in circumstances which require sliding contact with an O-ring seal which is disadvantageous.

Where the self-closing valve is to be applied to a purpose-designed tap rather than intended as an adapter for an ordinary screw action tap, the afore-mentioned valve body may be formed by the tap body.

In the above-described embodiments various means are employed to control the closing of the valve, but all share the use of the bellows seal in its basic form which provides a substantially frictionless seal between the valve stem and at least the end cap - also the valve body in the illustrated embodiment. The frictionless seal is advantageous as it makes control of valve closing easier using the above-described embodiments.

Attention is directed to U.K. Patent Application No.

from which this application is divided and which is directed to a self closing/time delay valve assembly and a water supply tape incorporating same and comprising a valve body adapted to fit in a water supply tap body, the valve body having a valve seat around a water inlet passage and receiving an axially slidably valve member having means to close off the water inlet passage in a closed position, the valve member being movable against resilient biasing, an end cap securable to the valve body and having an aperture through which an end of a spindle of the valve member projects for actuation purposes, and wherein sealing of the valve spindle with respect to at least the end cap is by sealing means comprising a first element disposed in surrounding sealing engagement with the valve spindle and movable therewith, a second element disposed in sealing engagement with at least one of the valve body or end cap, and a third sealing element surrounding the valve stem and connecting the first and second elements and being in the form of a bellows to allow axial movement of the spindle.

Claims

1. A self-closing/time delay valve assembly for a water supply tap comprising a valve body adapted to fit in a water supply tap body, the valve body having a valve seat around a water inlet passage and receiving an axially slidable valve member having means to close off the water inlet passage in a closed position, the valve is movable against resilient biasing, one end of the valve member extends sealingly from the valve body and carries an actuating plunger which makes sealing engagement the valve body to defme an air chamber between the plunger and the valve body from which air is expelled during an opening movement of the valve and wherein the admission of air to the chamber is restricted to control the rate of closing.

2. A valve assembly as claimed in claim 1 in which there is an adjustable bleed passage between the chamber and the external air (eg. atmosphere) by which the rate of air ingress can be adjusted and thereby adjust the rate of closing.

3. A valve assembly as claimed in claim 2 in which the rate at which air is admitted into the chamber is increased just before closing takes place.

4. A valve assembly as claimed in claim 3 in which rapid pressure equalisation is achieved by strategic positioning of port or passageway to breach the sealing arrangement of the plunger with the valve body at a predetermined position in the closing movement.

5. A water supply tap incorporating a selfclosing/time delay valve assembly according to anyone of claims 1 to 4.