This invention relates to a plug for sealing an outlet in a fluid container

and more particularly for sealing an outlet in a bath or sink.

It is common when baths or sinks are filled with water for a mixture

of both hot and cold water to be introduced into the bath in an attempt to

achieve a bath having water of a desired temperature. This usually involves

trial and error in the setting of the hot and cold water taps respectively, or

alternatively the mixer tap, to achieve a bath or sink having the water of the required temperature.

Consequently, accidents can happen in which persons step into or place their hands and/or arms and/or legs into water in a bath or sink which is too hot and therefore they can be burnt or scalded. This problem is particularly acute in the case of young children, the elderly, infirm or

disabled.

It is an object of the present invention to provide a plug which can

automatically release fluid from the outlet of a fluid container when the temperature of fluid exceeds a particular value.

According to the present invention therefore there is provided a plug for sealing an outlet in a fluid container, said plug comprising a body to seal

said outlet, said body, or at least a part thereof, being releasable from said outlet when the temperature of a fluid in the container exceeds a

predetermined temperature allowing fluid to flow through the outlet.

With this arrangement it is possible to allow a fluid container to

empty, or at the very least provide an indication that the temperature of the

fluid is too hot, when the temperature of the fluid exceeds a predetermined temperature. In this way the occurrence of accidents of the type mentioned

above can be minimised.

Preferably said plug body is formed from a resilient material and more

particularly may be formed from a rubber material. Preferably said plug body

is of conventional shape, having a dome shaped top surface and

substantially inwardly inclined side walls.

Preferably one end of a support member is connected to said plug

body and another end connected to an outlet of said container such that the

body is mounted for movement relative to said outlet. Said one end of said support may be embedded in said plug body during moulding of the body by

extrusion or otherwise. Said support member may be formed from a thermally expandable material, and it is felt that use of a bimetal strip is particularly suited to the present application. However, the support member can be formed from any suitable thermally expandable material. Alternatively, the support member may comprise a shape-memory effect material which changes state when a predetermined safe temperature is exceeded. In these cases the support

member may act directly on said body to release the body away from the

outlet as it expands linearly or changes state. Alternatively a heat sensor or

any other suitable means may be provided which senses the water

temperature and causes the body, or part thereof, to be released from the outlet when the temperature sensed exceeds a predetermined temperature.

A resilient biassing means may be provided which, on release of the

body, or part thereof, from the outlet when an excessive temperature is

sensed, biasses the plug body, or part thereof, away from the outlet.

If desired, a catch mechanism can be provided which normally holds

said plug body, or part thereof, in said outlet, said catch being releasable

upon sensing of a temperature above said predetermined temperature to

cause release of said body, or part thereof, from the outlet. In these circumstances, upon release of the catch mechanism, the plug, or part

thereof, may be moved upwardly away from the outlet under the action of

the spring on the support member.

As an alternative to the above, in the case where the plug is connected to the fluid container by a chain or similar, said support member may be arranged to act on the chain either directly, or indirectly, via an operative link to release the body, or part thereof.

Furthermore, it may be possible to form substantially the whole plug from a thermochromic material, or alternatively only a part of the body can

be formed from a thermochromic material, in either case wherein a visual indication of temperature can be provided.

The plug of the present invention can be mounted on a plug member,

one end of which is linked to the outlet and the other end of which is linked

to the body, the plug being movable between a lowered position in which

the outlet is sealed and a raised position in which the outlet is open and fluid can flow through the outlet by operation of a lever or other control member

linked to the plug member or plug via an operative connection.

It is thought that the present invention will find particular application

in the context of fluid containers such as baths or sinks, however the

invention can be used in any fluid container in which excessive temperature is desired to be avoided.

The invention will now be described further by way of example only

and with reference to the accompanying drawings of which:

Fig. 1 shows a diagrammatic representation of one form

of plug according to the present invention in a closed position; and

Fig. 2 shows the plug of Fig. 1 in an open position; Fig. 3 shows a diagrammatic representation of a

second form of plug according to the present

invention in a closed position; Fig. 4 shows the plug of Fig. 3 in an open position; and

Fig. 5 shows a plan view of the plug of Figs. 3 and 4.

Referring now to the drawings, there is shown in Fig. 1 a plug for a bath or sink outlet.

The plug 10 comprises a moulded rubber body 1 1 which has formed

integrally with, so as to depend downwardly therefrom, a support member 12. The support member 12 can be formed integrally with the plug body 1 1

by embedding one end thereof in the body 1 1 during moulding.

The support member 12 comprises, in one embodiment, a bimetal

strip, the constituent metals being chosen dependent upon the predetermined temperature required to be reached before the plug body 1 1

is moved away from the waste to allow the water to flow out of the bath or

sink, e.g. aluminium has a coefficient of linear expansion of 25 x 10 ⁶ /°C,

whilst nickel has a coefficient of 13 x 10 ⁶ /°C. Thus by appropriate choice

of the constituent metals, the support member 12 can be arranged to move

the plug body 1 1 away from the waste outlet at any predetermined

temperature. Alternatively the support member 12 can be formed from a

shape-memory effect material which is arranged to change state when a predetermined safe temperature is exceeded and this change of state can be utilised to move the plug body 1 1 away from the waste outlet.

Movement of the plug body 1 1 when the support member 12 expands, or the shape-memory effect material changes state, is biassed by a bias spring 13 which acts to control movement of the plug body 1 1 under

the action of the expanding support member 12. If desired, although not shown in the drawings, the support member

12 may include a catch mechanism which normally retains the plug in the outlet against the bias of the spring 13. When the support member 12

expands, it releases the catch mechanism, allowing the plug body 1 1 to

move away from the outlet under the action of the spring 13, the extent of movement being limited by the support member 12.

Thus it can be seen that the plug of the present invention allows the release of water from a bath or sink automatically if the water exceeds a

predetermined temperature which causes expansion of the support member to allow the plug body 1 1 to move clear of the outlet, whereby water can

flow out of the bath or sink, as shown in Fig. 2.

An alternative embodiment of plug is shown in Figs. 3 to 5 of the

drawings. In this embodiment a heat sensor 14 is mounted on an upper surface of the plug body 1 1 (see Fig. 5) adjacent the support member 12.

In this embodiment a catch mechanism (not shown) is provided which normally retains the body 1 1 in the outlet. When the temperature of the

water sensed by the heat sensor 14 is greater than a predetermined temperature, the heat sensor causes release of the catch mechanism, the

plug body 1 1 moves away from the outlet under the action of the spring 13 as in the previous embodiment, to allow water to drain out of the bath or

sink.

Of course, it will be appreciated that the heat sensor 14 can comprise

any suitable temperature sensing device of mechanised or electronic form. If necessary the sensor can be connected to the catch mechanism via an intermediate operative link of any suitable form.

Furthermore it will also be appreciated that in the case of either

embodiment, the plug is entirely re-usable.

Whilst in the above embodiments the plug body 1 1 as a whole is described as being movable away from the waste outlet once a

predetermined safe temperature has been exceeded, it is equally possible for only a part of the body 1 1 , for example a seal for a fluid outlet bore in the

body 1 1 , to be moved away to allow fluid to flow out.

Furthermore, instead of the support member acting on the plug

directly, it can be arranged to act on a chain which links the plug to the

container, whereby when a predetermined safe temperature is exceeded the

plug can be pulled out of the waste outlet. The support member can act

directly on the chain or via an intermediate operative connection.

Also it is possible to form a whole or a part of the plug body 1 1 from a thermochromic material whereby a visual indication of temperature of fluid in the container can be given.

It is of course to be understood that the invention is not intended to

be restricted to the details of the specific embodiments which are described by way of example only.