This invention relates to taps and is primarily concerned with adaptors for taps for use in public washrooms and the like.

A problem with taps in public washrooms is that if a conventional tap is used which can be turned on by turning the tap handle, the tap can be left on resulting in wastage of water. Attempts to solve this problem have been suggested in which a tap has to be pushed down in order to open it but the problem with this arrangement is that it is difficult to wash one's hands if one hand has to be used to hold down the tap in order to keep it open. Further, such pressed-down taps tend to become clogged with lime scale and like deposits so that, in time, only a very little amount of water flows when the tap is pressed down. Eventually, the tap can be held in the pressed down position so that water flows continuously or, in the alternative, the tap becomes so stiff that it cannot be pushed down at all-

Various delay means have been suggested in order to avoid the necessity of holding the tap down in order to keep it open while, at the same time, limiting the time in which the tap is on in order to prevent or at least limit the wastage of water. In one suggestion, an adaptor for a tap was provided which had an insert body having a central bore in which was located an actuator rod which opened the tap when depressed and which was biased to a closed position by a spring.

Return movement of the actuator rod to the closed position under the action of the spring was delayed by a piston movable in a chamber and connected to the actuator rod. A ring on the piston engaged the walls of the chamber and the frictional effect of this engagement delayed return of the actuator rod to the closed position. A major disadvantage of this arrangement is that the ring is susceptible to wear calling for frequent replacement if the delaying action was to function effectively.

In another suggestion, an actuator rod was again displaced by a pressing action to open a tap against the action of a spring which urged the actuator rod towards the closed position. In this case, return movement of the actuator rod was delayed by the engagement of a resilient ring on the actuator rod but, again, the ring was susceptible to wear so that frequent replacement is necessary if the delaying action is to function effectively.

The present invention aims to overcome the disadvantages of the existing taps by providing an adaptor for a tap which can be turned on and which allows water to flow with hands off operation for only a limited period of time and which avoids the use of friction rings and thereby avoids the need for frequent replacement.

According to the present invention, there is provided an adaptor for a tap comprising a body, a plunger slidably mounted within the body and movable in one direction relative to the body, spring means for urging the plunger in an opposite direction relative to the body and valve means for allowing said spring means to move the plunger in said opposite direction after a time delay effected by a time delay means.

Preferably, the body is symmetrical about a central longitudinal axis and has a cylindrical bore concentric relative to said axis, the bore having one portion of a larger diameter to form a chamber and another portion of reduced diameter

retaining said spring means, the plunger is of circular cross-section and has a first portion of larger diameter within the said one portion of the bore and a second portion of reduced diameter extending through the other portion of the bore and the spring means acts on a collar formed at the junction of the first and second portions of the plunger.

According to a preferred embodiment of the invention, the plunger is surrounded by a cup seal which allows fluid to pass from one side to the other side thereof when the body is moved in the said one direction but will not allow fluid to pass in the opposite direction and the time delay means comprises a passage within the plunger, spaced apertures extending through the plunger and a needle valve within the passage whereby the fluid can only pass in the said opposite direction by leaking through the spaced apertures and the needle valve.

The body may have a cylindrical extension, one end of the plunger extending through the extension and having a head which is arranged to close the tap until the plunger is moved in the said one direction.

The invention will now be further described, by way of example, with reference to the drawings, wherein: -

Figure 1 is a cross-sectional view of one embodiment of an adaptor for a tap according to the invention shown in the closed position;

Figure 2 is a cross-sectional view of the tap adaptor shown in Fig. 1 but showing the adaptor in an open position;

Figures 3A and 3B show valve means of the tap adaptor in open and closed positions, respectively;

Figure 4 shows a side view of an outlet part of the tap adaptor;

Figure 5 shows an exploded view of the outlet part; and

Figures 6A to 6E show different designs and/or sizes of outlet parts.

Referring to the drawings, an adaptor for a tap according to the invention comprises a cylindrical body 2 which is symmetrical about a central longitudinal axis and has a cylindrical bore concentric relative to said axis, the bore having one portion of larger diameter to form a first chamber 13 and a second chamber 14 and another portion of reduced diameter retaining spring means. Slidably mounted in the body 2 is a plunger 1 of circular cross-section which has a first portion of larger diameter within the portion of the bore of larger diameter and a second portion of reduced diameter extending through the other portion of the bore. The plunger 1 has a hollow tap head 3 mounted on a spigot on one end thereof which spigot has a circular recess around its circumference for the reception of a circlip 4 which retains the head 3 on the plunger 1. A cover 5 which may be decorative and made of metal or plastics material is a push-in tight fit in the top of the head 3 or is clipped in. The head 3 has a circular top plate with a circular hole to receive the spigot. Depending from the top plate is a cylindrical skirt which surrounds the body 2.

A control passage 7 of circular cross-section extends along the interior of the plunger 1. At one end of the passage 7 a cross-bore or aperture 9 of circular cross-section extends to the exterior of the plunger 1 and spaced therefrom and at the other end of the passage 7 two diametrically arranged and diametrically opposed apertures or holes 8 of circular cross-section extend into the chamber 14 at the exterior of the plunger 1.

Collars 10 and 11 formed on the exterior of the plunger 1 retain a circular cup seal 12 of V-shaped cross-section. The seal 12 forms on one of its sides one end of the chamber 13 within the body 2 and on its other side one end of the second chamber 14 formed within the body 2. The other end of the second chamber 14

is formed by a retaining cap 15 mounted on the body 2 and having apertures 16 for the passage of air. Between the collar 11 and a wall formed by an end or portion of the interior of the body 2 of reduced cross-section relative to the interior of the body 2 forming the chamber 13, there is arranged the spring means in the form of a coil spring 17.

A bore extends along the interior of the plunger 1 and one end of the bore forms the control passage 7. At the end of the plunger adjacent the spigot the bore is internally screw-threaded. A needle valve 6 has a screw-threaded boss 6A corresponding to the thread of the threaded portion of the bore. The needle valve is of metal or plastics material or may be moulded from plastics material with a tapered bore made during moulding. The needle valve 6 extends into the control passage 7 with the boss 6A engaging the internal screw-threading of the plunger 1. Rotation of the boss 6A causes the needle valve 6 to move along the bore of the plunger 1.

At the end of the plunger 1 remote from its end attached to the head 3 there is provided a tubular portion 18 of reduced cross-section relative to the parts of the plunger containing the needle valve 6. The tubular portion 18 has a friisto-conical collar 19 at one end thereof and a head 20 at the other end thereof, the collar 19 being provided with a rubber ring seal 21 and the head 20 being provided with a rubber ring seal 22. Surrounding the portion 18 is a cylindrical extension 23 projecting from the body 2.

As shown in Figure 5 the extension 23 has bayonets which fit into apertures of and locate an interchangeable thread member 24 to prevent rotation thereof, with a rubber ring seal 25 interposed between extension 23 and member 24. A thread retainer 26 has tines 27 which lock the thread member 24 in position and has a crown gear meshing with a corresponding gear on an interchangeable restrictor 28 which is clipped onto the extension 23. As shown by Figure 4 the restrictor

28 is rotationally adjustable prior to final location to adjust aperture alignment and thus eventual water flow rate.

The adaptor for a tap according to the invention operates as follows: -

1. Pushing plunger 1 down evacuates chamber 13 allowing air to pass seal 12 while allowing air into chamber 14 via aperture 16.

2. Upon release of the plunger the spring 17 forces the plunger up to create a low pressure resistance in chamber 13 maintained by seals 12 and 21 but allowing air to slowly leak through apertures 8 and aperture 9 via the adjustable tapered needle valve.

3. The time delay is created by adjusting the flow of air passing through the tapered needle valve from inlet aperture 8 to aperture 9.

4. The water flows in the direction of arrow X via outlet 30 in the direction of arrow Y. The water is shut off by seal 22 when plunger 1 is pushed back up.

As shown in Figures 3A and 3B the needle valve 6 is adjustable between two limit positions. The needle valve 6 by means of its screw-threaded boss 6A engages the screw thread in the plunger 1. The boss 6A can be turned with a screwdriver or like tool to move the valve 6 along the plunger. The needle has a machined bore of constant cross-section or is moulded with a tapered bore, the larger cross- section of the bore being towards the boss end of the needle. In the position shown in Figure 3 A the turning off of the tap is almost instantaneous whereas in the position show in Figure 3B there is the longest delay.

Figures 6A to 6E show various designs and/or sizes of thread members and restrictors to suit existing tap mountings. The body 2 and operating mechanism are standard for all taps and mountings.

The invention also extends to taps fitted with the adaptor above-described.