GB2263812A

GB2263812A - Piezo-electrically operated water supply valve

Info

Publication number: GB2263812A
Application number: GB9301415A
Authority: GB
Inventors: Jeffrey Charles Lowe
Original assignee: Armitage Shanks Ltd
Current assignee: Armitage Shanks Ltd
Priority date: 1992-01-28
Filing date: 1993-01-25
Publication date: 1993-08-04
Also published as: GB9301415D0; GB9201776D0

Abstract

A relatively vandal-proof control system for water supply in public wash stations uses a switch containing piezo-electric film material capable of generating a signal voltage when deflected, and connected to a solenoid operated water valve. The film may be protected by a relatively thick sheet metal layer such as brass 1mm thick.

Description

I?"PROVE'4ENTS .ELATING TO NATEP SUPPLY APPARATUS This invention relates to water supply apparatus primarily but not exclusively for asrooms, that is to say ablutionary or sanitary facilities especially ones provided for public use, for example but itout limitation, at motorway service stations.

In general there are two problems in such locations.

namely avoidance of waste of water. and resistance to damage by vandals. any different solutions to the problems have been proposed each with attendant advantage and disadvantage. The object of the present invention is to provide a new solution.

According to the invention we provide in combination, an electrically operated water valve, a switch, and a microprocessor connected to both and arranged to cause operation of the valve when the switch is operated, in which the switch comprises a piezoelectric film material enclosed in a cover Piezo-electric film material is based on polyvinylidene fluoride (PVDF) which has the piezoelectric characteristic imparted after manufacture as a film, or thin tape or sheet material. The present invention draws no distinction between films, tapes and sheets, any or all of which are believed to be suitable and all of which are to be included in the term film in this specification Both surfaces of the film are metallised. The film generates a proportional voltage when compressed or stretched.Such material is available commercially for example under the registered Trade Mark KYNAR Piezo Film in U.K. from Syrinx Innovations Limited of Edinburgh and in U.S.A. from Pennwalt Corporation of Philadelphia.

The film may be arranged in the form of a disc, coated with adhesive on one face and then adhered to and supported on a pad in a housing having a diaphragm-like cover for the film and the nousing may be arranged with tugs or apertures for securing to a wall, or for example as a two diameter body. having a large diameter shallow portion to receive the disc and a small diameter tubular portion to extend through a panel or wall and to carry electric conductors. In general. the switch is to be arranged above a lavatory basin or the like, so that it can be operated by a user to initiate a supply of water to that basin. The supply will be via a water pipe including a solenoid valve connected to the switch and circuitry, i.e. the water valve is opened when the solenoid is energised.

Typically, a disc of the order of 4O-5Omm will be employed, and the diaphragm (of like dimensions) may be made of a metal such as brass which can be for example chromium-plated or otherwise rendered resistant to corrosion, and the diaphragm may have a substantial thickness, of the order of lmm. This will render it resistant to attack by vandals even using knives, but is capable of deflection under mere finger pressure to generate the signal voltage. A mere tap of the finger will be sufficient.

The signal from the piezo film is connected to an operational amplifier, and in the circuit is compared to a reference signal, and an output pulse is activated when the piezo signal exceeds the reference signal, to actuate the solenoid, open the valve and bring about the supply of water.

It is at present preferred to include a memory and circuitry to effectively terminate the flow of water after a predetermined and possibly adjustable interval of say 15 secs., but it is equally possible to arrange for alternate signals to switch on the water supply and the intervening signals to turn off the water supply.

Claims

CLAIriS

1. In combination an electrically operated water valve a switch and a microprocessor connected to both and arranged to cause operation of the valve when the switch is operated, in which the switch comprises a piezoelectric film material enclosed in a cover.

2. The combination claimed in Claim 1 wherein the film is arranged in the form of a disc protected by a diaphragm-like cover which is sufficiently flexible to be deflected under mere finger pressure so that the film generates the required signal voltage.

3. The combination claimed in Claims 1 and 2 wherein the piezo film if connected to an operational amplifier, the signal is compared to a reference signal and an output pulse is activated when the piezo signal exceeds the reference signal to actuate the solenoid and open the valve and thus bring about the supply of water.

4. The combination claimed in any of Claims 1-3 including memory and circuitry to terminate the flow of water after a predetermined and adjustable interval.

5. The combination claimed in any of Claims 1 to 3 arranged so that alternate signals switch on the water supply and intervening signals switch off the water supply.