WATER OUTLET CONTROL SYSTEM

Abstract: Water outlet control system for controlling the shut-off valve(s) (4) of the water supply of one or more outlets (2), provided with a push button (5) for each outlet, placed near the outlet, a system of conduits and an electronic control unit (3). The push button (5) is a piezoelectric push button having a piezoelectric element (11) fitted on one side and an interface circuit (6) fitted on the other side of a carrier, which are accommodated in a watertight housing. The interface circuit has a switching element (7) connected parallel to the piezoelectric element and a rectifier bridge (8) which is fed by an alternating voltage from the electronic control unit (3). The switching element is short-circuited when the push button is not depressed and is open when the push button is depressed, while the control unit is actuated through brief operation of the push button and causes the valve to open for a set period of time.

Description: Water outlet control system The invention relates to a water outlet control system for controlling the shut-off valve(s) of the water supply of one or more outlets, provided with a push button for each outlet, placed near the outlet, a shut-off valve, a system of conduits and an electronic control unit. Such a water outlet control system is known in practice. In general, the costs of the water and energy consumption of water outlets, like showers and wash-basins, at camping sites, swimming pools, sports centres and similar public facilities con- stitute a major item of the budget. It goes without saying that efforts are made to keep these within bounds. It is currently known in practice to use mechanical self-closing taps for this purpose. However, the slightly higher water temperature used f.i. for taking showers, such as approx. 40 ea C, promotes scaling, which has an adverse effect on the proper functioning of these taps, so that changes in the running time or even continuous running of the tap could result. The object of the invention is to eliminate these problems and produce a water outlet control system with which an economical, reliable and vandalproof control of the water outlets is obtained, and which also provides a large number of setting possibilities. This is achieved according to the invention in a water outlet control system of the type mentioned in the preamble in that the push button is a piezoelectric push button having a piezoelectric element fitted on one side and an interface circuit fitted on the other side of a carrier, which are accommodated in a watertight housing, and the interface circuit has a switching element connect¬ ed parallel to the piezoelectric element and a rectifier bridge which is fed by an alternating voltage from the electronic control unit, the switching element being short-circuited when the push button is not depressed and being open when the push button is depressed, while the control unit is actuated through brief ope¬ ration of the push button and causes the valve to open for a set period of time. A number of individual water outlets, for example six, show¬ ers and/or taps, can advantageously be connected to this control system. The abovementioned period of time can be set individually in the control circuit at a desired value by means of a switch. It is also advantageous in this system to use low water hammer, self- cleaning magnet valves. The push buttons fitted near the showers are preferably vandalproof, watertight push buttons which are fitted in a watertight housing, for example a chrome-plated brass flange, together with an interface circuit. The system known from French Patent Specification 2,340,424 also has a central control unit, with a number of push buttons which each are added to a water outlet. Each push button is fitted in series with an electrical control circuit for the valve in a water supply conduit of the outlet in question. A major problem with this arrangement is the moisture-sensitive and non-vandalproof design of the control being implemented with the usual push but¬ tons. This means that economical and reliable control of the water outlets is not guaranteed. The invention will be explained in greater detail on the basis of an exemplary embodiment with reference to the drawings, in which: Fig. 1 shows schematically the water outlet control system according to the invention; Figs. 2a and 2b show schematically a front and side view of a flange according to the invention for the push button; Fig. 3 shows by way of example a diagram of an interface circuit belonging to the push button; Figs. 4a, 4b, 4c and 4d show different embodiments of the control unit of the system of Fig. 1. Reference is now made to Fig. 1. The water outlet control system comprises a central unit 1, in which a number of control circuits 3 corresponding to the number of water outlets, like showers 2 or wash-basins and such are accommodated. From this unit a number of supply lines run to the appropriate shut-off valves 4 and the push buttons 5 placed near the showers 2. Each individual shower has its own push button and valve. The push button is a piezoelectric pressure element. The housing shown in Figs. 2a and 2b comprises by way of example a chrome-plated brass flange containing a piezoelectric pressure element. The flange consists of a round disc 11 in which a conical chamber 12 is hollowed out from the rear side to receive the push button. During the manufacture it was decided that this chamber should be hollowed out, since in the case of a flange with inserted actuating plate the risk of moisture penetrating into shower or water areas is not ruled out. The circuit would then no longer function properly. The chamber is tapered to prevent the push button from being pressed out of the flange by too great a pressure on the pressure face 13 which is integral with the surface of the flange. The wall thickness of the round control face is 0.8 mm, which means that if for example too much force is applied, the yield point of the brass is not exceeded. The outside of the con¬ trol face on the flange can be designed with an engraving. This is done so that even after heavy use the control face remains recog¬ nizable, which would otherwise not be the case if a printed or painted marking were applied. The piezoelectric element is arranged in the hollowed-out chamber of the flange, and is fitted on the top side of the ceramic carrier. The interface circuit is fitted on the other or bottom side of the ceramic carrier, so that the said piezoelectric element and accompanying electronics of the interface circuit form an integral unit of SMD design. By means of a flexible cement and an insulator the piezoelectric element is fitted against the pressure face, and the whole unit is then cast in so that it is completely airtight. Fig. 3 shows by way of example a diagram of the push button 5 with the piezoelectric element 11 and the interface circuit 6, which can be made up of a parallel circuit of a switching element 7 and a rectifier element 8. This rectifier element is, for exam¬ ple, a diode bridge which is supplied with a low alternating vol¬ tage, which switches between 2 and 8 volt during operation. This diode bridge is fitted in particular in order to provide the possi¬ bility of switching with alternating voltage which comes from the electronic control unit set up some distance away. Since alter- nating voltage is taken as the supply, electrolysis is prevented from occurring. This would, when using direct voltage supply, result in corrosion of the connecting cable in the damp environment in which the push button is normally placed. In addition to this resistance to electrolysis, this circuit with alternating voltage supply also ensures that during the installation no distinction has to be made between a positive and a negative pole. By using this interface circuit in the push button it is also possible to trans¬ mit the signal over a great distance to the electronic control unit. By briefly pressing lightly on the brass control face the piezoelectric element 11 is actuated, which generates a small pulse voltage. This pulsating voltage is used to control the switching element 7, for example a Mosfet. When the piezoelectric element is not being operated, the switching element is conducting and is sup¬ plied by the direct voltage from the rectifier element. Through depression of the piezoelectric element a pulse voltage is supplied depending on the pressure on the brass pressure face. Due to this pulse voltage the switching element 7 is opened, so that the cur- rent in the supply is briefly interrupted. The thereby generated voltage change is compared with a reference voltage in the control circuit 3 in the control unit 1 and if this is exceeded a program¬ mable timer circuit 9 in the control circuit is started. This timer circuit can be set to a particular desired period of time, e.g. between 10 and 630 seconds. An electronic relay, which can actuate, for example, the shut-off valve such as a magnet valve, is in the end controlled by this timer circuit. The programmable timer circuit used is coupled to the elec¬ tric mains frequency, which ensures that great accuracy in running time is obtained. In Figs. 4a, b r c and d different possible embodiments of the control circuit 3 are shown. The control circuit in Fig. 4a is designed in such a way with the timer circuit 9 that, after brief operation of the push button, the period set by the timer circuit 9 begins and ends and in this period the shut-off valve is opened. This running time cannot be affected by depression in the meantime because via the feedback line 13 the input of the amplifier-comparator 13 is block¬ ed. On expiry of the period of time, the shut-off valve 4 is closed and, if desired, it can be actuated again for a new period of time. The control circuit in Fig. 4b, together with the timer circuit 9, is identical to the embodiment in Fig. 4a, but is fur¬ ther designed in such a way that, when it is closed after the expiry of the set time period, the shut-off valve 4 is blocked for an adjustable waiting period, so that another shower cannot be taken immediately. This waiting period is set with the delay cir- cuit 10 which is inserted in the feedback line 13. The control circuit in Fig. 4c is designed in such a way with the timer circuit 9 that during the course of the set period of time it can be interrupted by renewed operation of the push button, so that the valve then closes immediately and the period of time ends earlier. The control circuit in Fig. 4d is designed in such a way with the timer circuit 9 that during the course of the set period of time it can be started again by renewed operation of the push button and the shut-off valve 4 remains open until the set period of time has expired.

Claims: Claims 1. Water outlet control system for controlling the shut-off valve(s) of the water supply of one or more outlets, provided with a push button for each outlet, placed near the outlet, a shut-off valve, a system of conduits and an electronic control unit, charac¬ terized in that the push button is a piezoelectric push button having a piezoelectric element fitted on one side and an interface circuit fitted on the other side of a carrier, which are accommo- dated in a watertight housing, and the interface circuit has a switching element connected parallel to the piezoelectric element and a rectifier bridge which is fed by an alternating voltage from the electronic control unit, the switching element being short- circuited when the push button is not depressed and being open when the push button is depressed, while the control unit is actuated through brief operation of the push button and causes the valve to open for a set period of time. 2. Water outlet control system according to claim 1, charac¬ terized in that the push button with piezoelectric element and interface circuit is integrated in an SMD design in a watertight flange. 3. Water outlet control system according to claim 1 or 2, wherein the electronic control unit comprises a control circuit for each water outlet, characterized in that the control circuit is provided with an adjustable timer circuit, which on operation of the push button is started and produces a set period of time for opening of the valve. 4. Water outlet control system according to claim 1 , charac¬ terized in that the valve is a low water hammer, self-cleaning magnet valve. 5. Water outlet control system according to claim 3, charac¬ terized in that the control circuit with timer circuit is imple¬ mented such that, after closing on expiry of the set period of time, the shut-off valve is blocked during a waiting period, and remains closed. 6. Water outlet control system according to claim 3, charac¬ terized in that the control circuit with timer circuit is i ple- mented such that, during the course of the set period of time, it can be interrupted by renewed operation of the push button, so that the shut-off valve is closed earlier. 7. Water outlet control system according to claim 3, charac- terized in that the control circuit with timer circuit is imple¬ mented such that, during the course of the set period of time, it can be started again through renewed operation of the push button, so that the shut-off valve remains open until the set period of time has then elapsed.

Inventors: SMALLENBROEK FRITS, SMALLENBROEK, FRITS
Applicants: MELKER B V DE, DE MELKER B.V.
Application year: 1989
Main classification: E03C1
IPC codes: E03C1