GB2093607A - Method of controlling an appliance equipped with an electromechanical programming device - Google Patents

Abstract

The invention relates to a method of controlling an appliance equipped with an electro-mechanical step-by-step timer. The change-over from one step to the next is obtained by energizing the electric motor of the timer via a self- holding contact of the timer which is connected in series with a switch which is responsive to the existence of a specific physical condition (for example a temperature). The self-holding con tact 6 remains closed for a cycle of several adjacent programme steps P2, P3 and P4, the outer steps P2, P4 serving to actuate a first element of the appliance (for example, the heating element). Between the outer steps P2, P4 further steps (P3) are inserted for the actuation of at least one second element of the appliance (for example an electric valve). The invention makes it possible to provide two programmes on the timer by duplicating only certain cycles of said programmes. Application: Laundry washing machines. <IMAGE>

Description

SPECIFICATION Method of controlling an appliance equipped with an electro-mechanical programming device The invention relates to a method of controlling an appliance equipped with an electro-mechanical programming device, - the programming device comprising a plurality of electrical contacts which control the various elements of said appliance and which are arranged on rotatably coupled discs, which contacts are closed depending on the angular position of the discs which are driven stepwise by an electric motor, each programme step corresponding to the angular distance at which the array of contacts occupies the same configuration, - change-over from one programme step to the next being effected by energizing the motor via a self-holding contact which is closed by one of the discs, - the self-holding contacts being connected in series with a switch which is closed depending on whether a physical condition is obtained in the appliance.

Such methods are specifically used in programming devices of laundry washing machines. The discs of such devices may carry conductive tracks which make contact via wipers. More conventional types employ cam discs which co-operate with levers which open and close the contacts. Currently, such discs comprise at the most sixty positions or "programme steps", which enable the consecutive programme cycles of a washing machine to be carried out, such as: laundry pre-washing and heating, washing at a temperature of 40 C, 60"C, 90"C, several rinses, spindrying etc..., which cycles may each comprise several steps.For a specific programme the user sets the programming device to the first step of the first cycle of this programme and subsequently the programming device is advanced automatically, ensuring that the timing is correct and the physical washing conditions are met (namely filling, heating, water drainage...).

During the washing operations the washing machine may be filled to different levels or the water may be heated to different temperatures.

Two conventional solutions are possible: - the programming device should comprise as many programmes as there are programme options, from the first cycle (filling of the tub for the purpose of washing) to the last cycle (last rinse or spindrying). Such a solution is impossible because current programming devices have a limited number of steps (60), which cannot readily be increased, or - the programme options (filling levels, washing temperatures) are controlled by selectors operated by the user, outside the programming device. Since this solution results in one or more additional manual settings, the washing machine is more difficult to operate.

It is an object of the invention to provide the said facilities without the use of the aforementioned slutions. In a programming device of the type mentioned in the opening paragraph the method in accordance with the invention only necessitates the duplication of the programme cycle affected by a specific option. This method is characterized in that: - the self-holding contact remains closed over a cycle of several adjacent programme steps, of which the outer steps control a first element of the appliance which element serves to change a first physical condition, - between the outer programme steps of said self-holding cycle further steps are inserted for controlling at least one second element of the appliance.

When applied to the specific washing machine already described, the method may be further characterized in that: - in the outer programme steps of the self-holding cycle electrical resistors for heating the washing water are energized, a thermostatic switch being connected in series with the self-holding contact and the motor for actuating said contact when the desired water temperature is reached, - between the outer programme steps of the self-holding cycle there is provided at least one step in which a contact actuates an electric valve for filling the washing machine with water, and - the self-holding cycle is directly preceded by a programme step in which a contact also actuates said electric valve.

Such a method enables a specific washing programme to be carried out with different water levels, the operations of filling to said different levels and subsequent heating being the only operations which demand a duplication of programme steps.

The invention will now be described in more detail, by way of example, applied to a laundrywashing machine and with reference to the accompanying drawings.

The washing machine concerned is of such a conventional type that it is not shown in the drawings. It comprises a tub for the washing or rinsing water and, for example a rotatable drum containing the laundry to be washed. The washing programmes are controlled automatically by means of the electromechanical programming device which comprises cam discs which operate electrical contacts. The tub is filled with water by energizing an electric valve which remains open as long as a water-level detector is not actuated. The water is headed by, for example, an immersed electrical resistor ("immersion heater") controlled by a thermostat. The washing water is drained by means of a pump etc.

Figure 1 shows the wiring of an electric valve via which the tub of the washing machine is filled with water. Said electric valve 1 is connected to the mains terminals via one of the switches NB, NM, NH which are responsive to the level (low, medium, high) of the water in the tub. The switches NB, NM, NH are for example of the "pressostat" type, which respond to the static pressure of the water; they are in the positions sown (left-hand position) when the water level is below their actuating levels. In this position the switch N B directly energizes the electric valve, the switches NM and NH being connected in series with the electric valve and contacts 2 and 3 respec tively of the programming device, via which contacts the programming device enables the water level to be selected.In the right-hand position the switch NB, when the water has reached the low level, enables other elements of the washing machine to be energized, such as the motor 4 of the programming device, and a heater 7. The wiring for the right-hand position of the switches NM and NH is not shown.

The motor 4 of the programming device is for example a small synchronous motor. Its power supply depends not only on the low-level switch but also on two series-connected elements: the switch 5 of a thermostat, which is closed when the water temperature has reached the desired value, and a self-holding contact 6 whose closure is controlled by the position of the programming device and hence by the motor 4. Furthermore, the heating resistor (immersion heater) 7 for heating the washing water is arranged between contact 6 and the opposite supply line, in parallel with the thermostat 5 and the motor 4.

In the diagram of Figure 2 the consecutive programme steps of the programming device of the washing machine are plotted on the horizontal axis and the water levels N in the tub of the machine are plotted on the vertical axis. In the diagram the heavy lines represent the variation of the water level during the two programmes A and B, whose first cycles do not coincide (filling and heating), but whose last cycles are common (stirring, draining, rinsng etc...).

The continuous lines represent the situation for programme A, whilst the broken lines represent the situation for programme B. The electrical condition of the self-holding contact 6 of the programming device is indicated in Figure 2 below the N/P diagram (O = open, 1 = closed).

Programme A is, for example, intended for washing synthetic fabrics requiring a medium water level. In order to obtain this level the user sets the programming device to the programme step P1 which controls filling to the level NM via (Fig. 1) the electric valve 1, contact 2 of the programming device, and switch NM, whose change-over interrupts filling. During and/or after filling the programming device remains at step P1 for a time interval of, for example two minutes. During this time the laundry may already be stirred. In order to obtain this time lag, which is symbolised by 8 in Figure 1, the motor 4 is energized and advances the programming device to step P2.At this programme step the washing water is heated to the temperature set with the thermostat 5, the self-holding contact 6 of the programming device being closed as indicated by the diagram of Figure 2. The heating resistor 7 is energized via said self-holding contact 6. This sequence of heating the water at constant level is represented in the diagram Fig. 2) by a series of dots.

When the temperature setting of the thermostat 5 is reached the motor 4 is energized again until the end of the self-holding cycle, that is to say until the beginning of programme step P5. The programming device steps through the programme steps P3 and P4 without stopping, in which steps the electric valve 1 and the heater 7 are briefly energized without significantly altering the level and temperature of the water in the tub (thin continuous line in diagram). In programme step P5 the laundry is stirred in the hot water to which detergent has been added. This stirring is for example effected for some minutes, after which the motor of the programming device is energized by the timing device 8. The next programme step P6 comprises a timed drainage of the washing water.In step P7 the tub of the machine is filled with fresh water up to the high level and the laundry is stirred for a few minutes for the first rinse, subsequently the steps P8 ... etc. comprise consecutive draining and rinsing operations and, as the case may be, spindrying of the laundry.

Programme B is for example intended for washing delicate fabrics (silk) requiring much water. For this programme the user sets the programming device to the programme step P3, which results in filling to the level NH by means of the electric valve 1, the contact 3 of the programming device and the switch NH.

Subsequently, the motor is energized and advances the programming device to the step P4. The water is heated to the desired temperature set by the thermostat (for example 30"C for delicate fabrics). When this temperature is reached the motor is energized via the thermostat 5 and the self-holding contact 6, and the programming device is thus advanced to the step P5. Frnm this instant programme B proceeds in the same way as the programme A described in the foregoing.

If for example programmes A and B comprise 9 steps from the first filling operation before washing till the last draining operation after rinsing the programme requires only 11 programme steps as a result of the combined starting cycles instead of 18 steps if said two programmes were provided separately on the programme device.

Claims (3)

1. A method of controlling an appliance equipped with an electro-mechanical programming device.

-the programming device comprising a plurality of electrical contacts which control the various elements of said appliance and which are arranged on rotatably coupled discs, which contacts are closed depending on the angular position of the discs which are driven stepwise by an electric motor, each programme step corresponding to the angular distance at which the array of contacts occupies the same configuration.

- change-over from one programme step to the next being effected by energizing the motor via a self-holding contact which is closed by one of the discs, -the self-holding contact being connected in series with a switch which is closed depending on whether a physical condition is obtained in the appliance, characterized in that the self-holding contact remains closed over a cycle of several adjacent programme steps, of which the outer steps control a first element of the appliance, which element serves to change a first physical condition, and - between the outer programme steps of said self-holding cycle further steps are inserted for controlling at least one second element of the appliance.

2. A control method as claimed in Claim 1, applied to a laundry-washing machine, characterized in that - in the outer programme steps of the self-holding cycle electrical resistors for heating the washing water are energized, a thermostat switch being connected in series with the self-holding contact and the motor for actuating said contact when the desired temperature is reached, - between the outer programme steps of the self-holding cycle there is provided at least one step in which a contact actuates an electric valve for filling the washing machine with water, - the self-holding cycle is directly preceded by a programme step in which a contact also actuates said electric valve.

3. A method of controlling an appliance substantially as herein described with reference to the accompanying drawing.