GB2156389A

GB2156389A - Water supply control in a household appliance

Info

Publication number: GB2156389A
Application number: GB08501131A
Authority: GB
Inventors: Ernst Stickel; Helmut Jerg
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-03-23
Filing date: 1985-01-17
Publication date: 1985-10-09
Also published as: SE8501369L; IT1185075B; GB2156389B; SE8501369D0; DE3410826A1; SE457916B; IT8521129V0; GB8501131D0; FR2561797A1; DE3410826C2; FR2561797B1; IT8519935A0

Abstract

A water-conducting household appliance, especially a dishwashing or laundry washing machine, has a shut-off valve (28) which is connected in series with a program-controlled electromagnetic water feed valve (7), is held by a permanent magnet in an open rest state and is closable by a pressure-sensitive element (29) which is connected to an air trap chamber of a vessel (21). The chamber monitors a liquid level in a tube (1) of the appliance, is fillable by way of an overflow edge at the liquid level and is emptiable by a siphon. The shut-off valve (28) with the pressure-sensitive element (29) and the air trap chamber set to a normal filling level (19) of the tub (1) is provided for level regulation, whilst the electromagnetic water feed valve (7), which is switchable by way of a timing element of program control equipment of the appliance, monitors the shut-off valve (28). <IMAGE>

Description

SPECIFICATION Water supply control in a household appliance The present invention relates to a household appliance operable with water, in particular to water supply control in an appliance such as a laundry washing machine, a dishwashing machine, or the like.

Certain dishwashing machines available on the market are equipped with a safety device of the kind described in DE-PS 3114 664. By means of this safety device, a water supply shut-off valve is open in a rest position in the case of trouble-free operation of the appliance. Water feed into the tub of the appliance takes place through opening of an electromagnetic water feed valve switched by the appliance control. When the normal filling level is reached, a level monitor effects closing of the electromagnetic water feed valve.

Arranged for this purpose at a side wall of the tub is a level regulating device which comprises a housing of plastics material and has a first air trap chamber for the normal level, a second air trap chamber for a safety level and a chamber in which are provided drop ducts of siphons for the emptying of both air trap chambers. The housing chamber is connected by way of a connecting stub pipe to the tub or to an outlet trough at the base of the tub or to the emptying system of the tub.

Separating walls with overflow edges at the height of the normal filling level or at the height of the safety level of the tub are provided between the housing chamber and the air trap chambers.

The level monitor (pressure monitor) which effects the closing of the electromagnetic water feed valve is connected to the first air trap chamber responding to the normal filling level. A pressure-sensitive element of the shut-off valve is connected to the second air trap chamber responding to the higher safety level.

On failure of the level monitor or non-closing of the electro-magnetic water feed valve, the water level in the tub reaches the safety level at which the second air trap chamber is influenced and a diaphragm, which is directly subjected to the pressure of the liquid, of the pressure-sensitive element of the shut-off valve lifts a permanent magnet thereof so far from its armature in the valve housing that the shut-off valve blocks the further feed of water.

The pressure loading of the diaphragm is reduced during the emptying of the tub so that the permanent magnet returns to its initial position and in that case attracts the armature in the shutoff valve and thus transfers the shut-off valve into its open setting. In order to detect leakages, a leakage water collecting trough is provided at the base of the appliance, a float being arranged in the trough and coupled directly with the diaphragm of the pressure-sensitive element of the shut-off valve in such a manner that, if leakage water collects in the trough, the float is raised and by way of the diaphragm deflects the permanent magnet and closes the shut-off valve.

There is scope, however, for such a level-regulating and safety device to have a simpler construction.

According to the present invention there is provided a household appliance operable with water and comprising a first inlet valve to control water supply to a container of the appliance, means to hold the valve in an opened state, pressure-sensitive means actuable by pressure to cause closure of the valve, pressure-generating means comprising an air trap chamber to receive water when water in the container exceeds a predetermined level, the chamber being so arranged that inflowing water generates a pressure to actuate the pressure-sensitive means, a second inlet valve connected in series with the first valve and means to cause closing of the second valve in dependence on time so as to provide an overriding control of the water supply to the container.

In a preferred embodiment, the first or shut-off valve is connected in series with a program-controlled electromagnetic water feed valve, is held by a permanent magnet in an open rest position and is closable by a pressure-sensitive element which is connected to the air trap chamber for monitoring the liquid level in a tub of the appliance. The chamber is fillable by way of an overflow edge at the liquid level and is emptiable through a siphon.

The shut-off valve with the pressure-sensitive element and the air trap chamber set to the normal filling level of the tub are provided for level regulation and the electromagnetic water feed valve, which is switchable by way of a timing element of program control equipment of the appliance, monitors the shut-off valve. Because the shut-off valve, which is actuable mechanically and by permanent magnet, is provided for level regulation, and the controlled electro magnetic water feed valve, switchable with time overlap, forms the safety part, the entire arrangement can be simplified without impairing the accuracy of the level regulation or the protection against overfilling of the tub.A second air trap chamber for the safety level with overflow edge and siphon, and an operational level monitor its function being taken over by the pressure-sensitive element with its contacts and connections, are redundant.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic circuit diagram of a dishwashing machine embodying the invention; and Figure 2 is a sectional elevation of a level-regulating vessel of the machine of Fig. 1.

Referring now to the drawings, there is shown in Fig. 1 part of a dishwashing machine comprising a tub 1 with an outlet trough 2 which is arranged in the base of the tub and is connected to an emptying pump and a circulating pump (not shown). Disposed above water softening equipment, consisting of a salt or brine container 3 and an ion exchanger 4, is a storage container 5, which is arranged at a side wall of the tub and from the base of which an outlet duct 6 leads into the container 3. The dish washing machine is connected by way of an electromagnetic water feed valve 7 to a water duct 8. A fresh water duct 9 leads from the valve 7 by way of a free flow path 10, disposed in the container 5, and a raw water valve 18 to the ion exchanger 4, from which a duct 11 leads to the trough 2. A duct 13 leads from an overflow 12 of the container 5 into the ion exchanger 4.

In the illustrated embodiment, the container 3 has a closable fill ing stub pipe 14 and a ventilation hose 15, while a regenerating valve 17 is disposed in a connecting duct 16 to the ion exchanger 4.

For the monitoring of a normal filling level 19 of the tub 1, there is provided a level regulating vessel 21 which, as shown in Fig. 2, has an air trap chamber 22, a housing chamber 23, a separating wall 24 with an overflow edge 25 at the height of the normal filling level, and a siphon 26 capable of emptying the air trap chamber. The vessel is connected by way of a stub pipe 20 to the tub 1 or the outlet trough 2 thereof. The air trap chamber 22 is connected by way of a control duct 27 with a pressure-sensitive element 29 controlling a shut-off valve 28, which is arranged in the duct 8 downstream of the valve 7 and may be of the kind described in DE-PS 3114 664.

The level-regulating and safety functions take place in the following manner: In trouble-free operation of the appliance, the shut-off valve 28 is held open by a permanent magnet. The water feed into the tub 1 takes place on opening of the electromagnetic water feed valve 7 switched by the program control. When the normal filling level 19 in the tub 1 is reached, a small quantity of the water entering the vessel 21, which communicates with the tub, overflows the edge 25 and passes into the air trap chamber 22. A small quantity of water is sufficient for the air trap chamber 22 to build up a pressure which, by way of the control duct 27, acts on the pressure-sensitive element 29 in such a manner that the shut off valve 28 is transferred to its closing state and prevents further feed of water.

The valve 7, which is switched by way of a timing element of the appliance control, is also closed after lapsing of its predetermined opening time.

During emptying of the tub and/or after switching-on of the circulating pump, the water level is lowered and the siphon 26 can start up for emptying of the air trap chamber 22, whereby the pressure loading of the pressure-sensitive element 29 is reduced and the valve 28 is transferred back to its open setting. By virtue of operation of the shutoff valve mechanically and by permanent magnet, seizing of the valve is counteracted. Moreover, according to the design of the level-regulating vessel and the opening time of the valve 7, a dynamic refilling of water into the tub is possible when the valve 28 reopens after starting-up of the circulating pump.

If the water feed to the tub on reaching of the normal filling level 19 is not interrupted due to a fault, for example clogging of the level regulating vessel or failure of the pressure-sensitive element, then water still flows to the tub until the opening time of the valve 7 has ended.

This opening time can be so designed that the tub, in the arising safety case, is filled only slightly above the normal filling level.

In order to check leakage at the tub or at the other water-conducting components of the appliance, leakage water can be collected in a collecting trough at the base. Arranged in the collecting trough is a float which is so coupled with the pressure-sensitive element 29 that it effects the closing of the shut-off valve after a small quantity of leakage water has collected in the trough.

In place of the overflow edge 25 of the separating wall 24, the separating wall can be higher and the base 30 of the siphon 26 arranged at the height of the normal filling level 19 so as to take over the function of the overflow edge during the water inflow into the tub 1.

Claims

1. A household appliance operable with water and comprising a first inlet valve to control water supply to a container of the appliance, means to hold the valve in an opened state, pressure-sensitive means actuable by pressure to cause closure of the valve, pressure-generating means comprising an air trap chamber to receive water when water in the container exceeds a predetermined level, the chamber being so arranged that inflowing water generates a pressure to actuate the pressure sensitive means, a second inlet valve connected in series with the first valve and means to cause closing of the second valve in dependence on time so as to provide an overriding control of the water supply to the container.

2. An appliance as claimed in claim 1, the means to hold the valve in an opened state comprising a permanent magnet.

3. An appliance as claimed in either claim 1 or claim 2, the second valve being an electromagnetically actuable valve and the means to cause closing of the second valve comprising a timing element of a programme control device of the appliance.

4. An appliance as claimed in any one of the preceding claims, comprising a sump to collect leakage water in the appliance and a float arranged in the sump and displaceable by water collecting in the sump to cause actuation of the pressure sensitive means.

5. An appliance as claimed in any one of the preceding claims, wherein the air trap chamber is so arranged to receive water by way of an overflow edge arranged at a given normal filling level of the container that the pressure generated by such water causes actuation of the pressure-sensitive means when the water in the container has reached the normal level, the means to cause closing of the second valve being actuable to close the second valve after a predetermined time sufficient to permit inflow into the water of a volume of water at least equal to that required to fill the container to the normal level, and the means to hold being actuable to restore the second valve to its opened state on emptying of the container and the air trap chamber.

6. An appliance as claimed in any one of the preceding claims, the emptying means comprising a siphon.

7. An appliance as claimed in claim 6 when appended to claim 5, wherein the elbow of the siphon is arranged at the height of said normal filling level and defines said overflow edge.

8. An appliance as claimed in any one of claims 1 to 7, the appliance being a laundry washing machine.

9. An appliance as claimed in any one of claims 1 to 7, the appliance being a dishwashing machine.

10. A household appliance substantially as hereinbefore described with reference to the accompanying drawings.