Control for the hot water supply for an automatic washing machine

Abstract: The invention relates to a control for the hot water supply to an automatic washing machine with a hot water and a cold water valve and a thermostat which may be adjusted to different switching temperatures. Monitoring of temperature is obtained with simplified power circuits, with reduced outlay on parts, for the hot water and cold water valve by means of the adjustable thermostat.

Description: The invention relates to a control for the hot water supply to an automatic washing machine with a hot water and a cold water valve and a thermostat which may be adjusted to different switching temperatures. A control for the hot water supply of this type is used in the automatic washing machines WA 9430 and WA 9437 by the applicant. In this known control for the hot water supply, a switch relay and a break contact on the thermostat are connected in series with the hot water valve. The switch relay switches from the cold water valve to the hot water valve. The arrangement is such here that, when the thermostat is adjusted to a lower switching temperature of e.g. 35°C at the beginning of the operation to supply the hot watery the contact of the switch relay opens the circuit of the cold water valve and closes that of the hot water valve. When the adjusted switching temperature is achieved, the contact of the thermostat opens the circuit for the switch relay, with the result that the circuit for the cold water valve is switched back on again. When the thermostat is adjusted to a higher switching temperature of e.g. 60°C, then, even after reaching the temperature, the circuit of the relay remains closed, since a switch contact overrides the contact of the thermostat. As before, the circuit for the hot water valve remains switched on. This known control for the hot water supply requires, besides the switch relay, a contact switch on the adjustable thermostat and a thermostat with a fixed temperature as well. The object of the invention is to simplify a control for the hot water supply of the type mentioned at the outset in such a way that the outlay on parts is reduced and that the temperature can be monitored and regulated during the filling stages. This object is achieved according to the invention in that, during the operation of supplying hot water, the cold water valve is brought into the opening position independently of the switching state of the thermostat, in that, until the switching temperature preset by the thermostat is reached, a contact of the thermostat directs the hot water valve into the open position and in that, in bypassing the preset switching temperature the thermostat reacts and, with its contact, interrupts the controlling current of the hot water valve. The switch relay and the contact switch on the thermostat are inactivated and the adjustable thermostat controls the temperature in the filling stage so that temperature excesses are avoided in the heating stages. According to one development, the cold water valve can also be controlled independently of the operation for supplying the hot water. For this purpose, control contacts of the program control unit, which can be adopted without alteration from known automatic washing machines, can be used in an already known manner. Since the cold water valve is now opened during every hot water supply, according to a further development, subsequent heating can be introduced if higher mixing temperatures are desired. The invention is described in greater detail with the help of an embodiment given by way of example and represented in the drawing as a circuit diagram. The circuit diagram does not go into the details of the program control unit, of which only the control contacts sw, sk1, sk2 and sh are shown in the circuits. The control contact sw is closed, if hot water is desired. A circuit for the hot water valve WVHF is thus closed, in which circuit a break contact th of the thermostat TH, which can be adjusted to various temperatures, is also included. The circuit for the cold water valve WVL leads via the pump P and is controlled by the control contacts sk1 and sk2, which are likewise part of the program control unit. The cold water supply can be introduced thus independently of the hot water supply as well as in parallel with the latter. This presetting is taken on by the program control unit. The thermostat TH may be adjusted to various switching temperatures. The circuit for the hot water valve WVHF remains closed until the contact th of the thermostat TH opens. The hot water supply is stopped when the mixing temperature, which is preset by the adjustment of the thermostat, is exceeded, since, when the mixing temperature is reached, the thermostat TH reacts, opens its contact th and thus switches off the hot water valve WVHF. The hot water valve WVHF closes and stops the hot water supply. The cold water valve WVL remains under the control of the program switching unit and therefore in its open position. The cold water supply takes place then, during the entire operation for supplying the hot water, parallel to the hot water supply. When higher mixing temperatures, e.g. 60°C are desired, it can become necessary to heat the water subsequently in the filling stages. For that purpose, the heating element H is correspondingly controlled via control contacts sh in the program control unit.

Claims: Control for the hot water supply to an automatic washing machine with a hot water and a cold water valve and a thermostat, which may be adjusted to different switching temperatures, characterised in that , during the hot water supply operation (control contact sw) the cold water valve (WVL) is brought into the opening position independently of the switching state of the thermostat (TH) (control contacts sk1, sk2), in that , until the switching temperature (e.g. 30°C or 60°C), which is preset by the thermostat (TH), is reached, a contact (th) of the thermostat(TH) directs the hot water Valve (WVHF) into the open position, and in that , when the predetermined switching temperature (e.g. 30°C or 60°C) is exceeded, the thermostat (TH) reacts and interrupts the control circuit of the hot water valve (WVHF) with its contact (th). Control for the hot water supply according to Claim 1 characterised in that , the cold water valve (WVL) may be controlled independently of the operation for supplying the hot water ( control contacts sk1, sk2). Control for the hot water supply according to Claims 1 or 2 characterised in that , when higher mixing temperatures (e.g. over 60°C) are desired, subsequent heating may be introduced (control contact sh for heating element H).

Inventors: KLINGENSTEIN DIETER, KLINGENSTEIN, DIETER
Applicants: WHIRLPOOL CO, WHIRLPOOL CORPORATION
Application year: 1998
Main classification: D06F39
IPC codes: D06F39