DE69622779T2 - Washing machine with temperature selection switch - Google Patents

Description

The invention relates to washing machines, in particular for washing laundry, according to the preamble of claim 1.

As is well known, most washing machines, especially laundry washing machines, are equipped with a program selector switch with which the user can select a washing program from a number of different washing programs depending on the items to be washed. This program selector switch, which essentially consists of an electromechanical program control switch, appropriately controls a series of elements within the machine by means of which the washing process is carried out.

As is known, electromechanical program selectors contain an electric motor that drives a group of cams from the beginning to the end of the selected washing program for a preset time. The cam profile is designed to activate some electrical contacts that activate the said elements of the machine at the given time and for a given period. In a simple example, the first cam switches a solenoid valve to let water in from the water connection until a pressure switch contact interrupts the water supply to the solenoid valve. A second cam activates a heating device to heat the incoming water until a thermostat detects that a preset temperature has been reached. A third cam causes the rotation of the motor to be transmitted to the drum filled with laundry. A fourth cam activates a drain pump to pump out the washing water, etc. In any case, the characteristics of cam program selectors are known per se, so that a more detailed description of their operation is not necessary in the context of this description.

As is well known, most washing machines, especially laundry washing machines, are also equipped with a selector for choosing the washing water temperature. This selector allows the user to choose the desired temperature depending on the type of laundry, with the temperature range normally being between 0ºC and 95ºC. For example, to wash delicate items, the user chooses a relatively low temperature (e.g. 30ºC), while to wash heavily soiled items, he chooses a much higher temperature (e.g. 90ºC).

As is well known, when a temperature above 60ºC is selected, additional cold water is added before draining the water used for a high temperature wash cycle (e.g. 90ºC).

The purpose of adding additional water, which is normally done at the end of a hot wash cycle and before a cold rinse cycle, is to prevent a temperature shock to the laundry that would result from the transition from a high water temperature (the water used for the wash cycle) to a very low temperature (the water used for the rinse cycle).

Furthermore, with regard to the temperature of the washing solution that can be achieved, some countries now have specific regulations in place which stipulate that washing machines may not discharge water into the sewer system at a temperature higher than a predetermined threshold, in particular around 60ºC.

It follows from the above that the machine itself should lower the water temperature to the threshold before draining the water after a wash cycle if the user has set a temperature above 60ºC.

This is done in the way described above, i.e. by letting a certain amount of water into the washing machine tub to reduce the temperature of the water already contained in it. At the end of the actual wash cycle and before the water is drained, a cam on the programme selector allows an additional injection of around 7 to 8 litres of cold water. As this additional injection of water reduces the temperature of the washing water, the water can be drained off in accordance with the regulations and cold water is prevented from coming into contact with the hot laundry, i.e. a thermal shock for the laundry is avoided.

The additional cold water supply is achieved by operating the contacts of a pressure switch normally present in washing machines and designed for two different levels, namely a first level for the normal wash cycle and a second level, above the first level, to allow the supply of additional water at certain phases of a wash cycle, for example, the aforementioned additional feed to lower the temperature of the washing solution.

From the above description, it is clear that for wash cycles at temperatures below 60ºC, an additional water supply to prevent thermal shock or to reduce the water to be drained is not necessary, so that when such a temperature is set, it is also not absolutely necessary to operate the pressure switch for the second level to supply additional water.

However, in machines with an electromechanical cam program selector, where a special cam controls the activation of the second level of the pressure switch, it is not so easy to prevent the introduction of additional water. This is mainly due to the space requirements of the cam group. In fact, it would be quite complicated to provide more individual cams to switch off the second level of the pressure switch when a different temperature is selected.

For the reasons mentioned above, washing machines with electromechanical program switches actually use about 7 to 8 liters more water than is absolutely necessary. This obviously represents a considerable waste.

EP-A 0 225 550 discloses a rotary switch device for program selection in washing machines, where the temperature can only be selected within a certain range depending on the laundry.

The invention has the object of solving this problem and in particular of providing a washing machine which can avoid unnecessary water waste in a relatively simple and cost-effective manner and reduces the temperature of the washing solution during a washing process.

In this context, a further object of the invention is to provide a washing machine in which the function of limiting water consumption is assigned to a control element that forces the user to decide on a washing temperature to be selected.

According to the invention, the above objects are achieved by providing a washing machine, especially for washing laundry, which has the features set out in the appended claims, in which the teachings for carrying out the invention are summarized.

Features and advantages of the invention will become apparent from the following description and the accompanying drawings, which are for illustrative purposes only and are not to be understood as limiting, and which show the following:

Fig. 1: a schematic view of a washing machine according to the invention;

Fig. 2: a partial view of the simplified circuit diagram of the washing machine of Fig. 1;

Fig. 3: a schematic sectional view of a detail of a washing machine, which represents a possible variant of the invention.

In Fig. 1, reference numeral 1 designates a washing machine according to the invention as a whole.

This could be, for example, a machine of the type mentioned at the beginning of this description with all known functional elements.

The reference number 2 designates the loading door of the machine and 3 the control panel. The control panel contains the detergent drawer marked 4, the main ON/OFF switch marked 5 and the electromechanical program selector marked 6, which offers a choice of different washing programs.

The control panel 3 also has a second button, marked 7, which belongs to a washing temperature selector switch with which the user can choose between different temperatures. According to the state of the art, the temperature selection range is, for example, between 0 and 95ºC.

According to the invention, the control panel 3 additionally has the button designated 8, which has two functions. When the button 8 is pressed, the washing solution can be heated to a temperature higher than the predetermined limit temperature, which in this example is 60ºC.

In other words, if the user wants to wash at a temperature of 90ºC, this is only possible if button 8 is pressed. This function is based on the fact that washing temperatures above 60ºC can damage the laundry, as such temperatures are only suitable for certain thorough treatments and only for laundry that can withstand such high temperatures.

If only a simple temperature selection knob is provided, it can lead to misuse. Just think of a user who has put delicates in the machine and then inadvertently sets the temperature selection knob to a higher temperature than is good for the laundry.

According to the invention, the first important function of button 8 is to sensitize the user when selecting a so-called "dangerous" temperature, i.e. to force him to make a conscious decision during this process (temperature selection).

According to the invention, button 8 has a second important function. Button 8 is specifically connected to suitable switching means which allow the supply of additional water only when button 8 is pressed, i.e. when a temperature above 60ºC has been selected. In practice, button 8 therefore has the function of activating the second pressure switch level for lowering the temperature of the washing solution only in the cases already mentioned at the beginning of this description, i.e. only when actually needed.

Therefore, if the user selects a temperature between 0 and 60ºC, the machine will not take in an additional 7 to 8 litres of water. Conversely, the additional water supply to lower the temperature of the wash liquor in the tub will only take place if a temperature above 60ºC has been set, i.e. only if button 8 has been pressed.

This means that button 8 has the dual function of alerting the user to the fact that he wishes to set a high washing temperature and of enabling him to make a significant saving in water.

Fig. 2 shows, by way of example, part of a simplified circuit diagram for the washing machine of Fig. 1, which is limited to the area of the circuits associated with button 8. This figure thus practically only shows the part of the circuit diagram which, in the machine according to the invention, contains a modification compared to the prior art. It can therefore be assumed that the rest of the circuit diagram corresponds essentially to the circuit diagram of known machines. In Fig. 2, EV designates a solenoid valve for feeding water into the machine, P1 designates the electrical contact of a pressure switch for the first level (i.e. the lower level) and P2 designates the electrical contact of a pressure switch for the second level (i.e. the higher level). The contacts P1 and P2 are preferably contained in a pressure switch which can detect the two different levels. The properties and functionality of such a pressure switch are not described in detail, because they correspond to the already known concept used in practically all commercially available washing machines.

RR indicates a heater for heating the washing solution, while 8 indicates the aforementioned button which allows the selection of a temperature above 60ºC. As can be seen, this button 8 is provided with two bypasses.

C1 designates a cam on the program selector or the electromechanical timer 6 of the washing machine, which, if necessary, activates the second level of the pressure switch at the appropriate time of a wash cycle.

C2 is a second cam, which is normally used in the well-known program selector switches and which switches on the heating device for the washing solution at the right time.

C3 designates a third cam whose task is to activate the second level of the pressure switch P2 for the additional water supply mentioned above.

In the known washing machines, however, the additional water supply is controlled by cam C1, which has the consequences for water consumption already described at the beginning. Cam C3 in the invention is therefore an additional cam compared to the prior art.

Finally, TM1 and TM2 are two thermostats for controlling the heating device RR. The thermostat TM1 establishes or interrupts the power supply to the heating device RR in the temperature range from 0 to 60ºC, while the thermostat TM2 establishes or interrupts the power supply to the heating device RR in the temperature range from 61 to 95ºC.

The circuit section shown in Fig. 2 functions as follows:

For example, let's assume that the user wants to operate the machine at a washing temperature of up to 60ºC. In this case, button 8 and the associated two deviator circuits do not need to be pressed. The two diverter contacts have the position shown in the figure.

The solenoid valve EV is powered by the conductor L via the contact P1, which is in the position shown in Fig. 2. When the first liquid level is reached, the pressure switch P1 switches, i.e. the contact is brought into the right position shown in Fig. 2. At the same time, the cam C1 is also brought into the right position, whereby the "full" signal from the pressure switch P1 is passed via the conductor P and the subsequent washing cycle is switched on via the timer 6 of Fig. 1 (e.g. rotation of the washing drum).

If, after the wash program, the washing solution is heated to 90ºC, the cam C2 is moved to the left position, thus powering the heater RR until the thermostat TM1 indicates that the washing solution has reached the preset temperature. As can be seen from the figure, the thermostat TM2 does not start to work to heat the washing solution to a temperature above 60ºC if the button 8 is not pressed, because in this case the washing solution cannot reach a temperature higher than 60ºC.

When the second water level is required even though the temperature is 60ºC or less (for example in the case of wash programs for special laundry such as synthetics, which require a greater quantity of water), cam C1 is moved to the left position of Fig. 2. Then, when the first water level is reached, the contact of P1 moves to the right and the contact of P2 is immediately activated by cam C1, so that the solenoid valve EV is fed until the second water level is reached. Then P2 switches, moving the contact to the right position of Fig. 2 and cutting off the feed to the solenoid valve. Also in this case, the "full" signal, i.e. the reaching of the set water level, can reach P, as described above.

As already mentioned, button 8 must be pressed if washing is to be carried out at a temperature above 60ºC.

Let us assume that the liquid in the vat has already reached the first level and the contact of P1 is already in the right position.

When the additional water supply at room temperature is required according to the selected washing program in order to reduce the temperature of the suds in the tub, the cam C1 is in its central rest position as shown in Fig. 2, while the cam C3 is on the left and the cam C2 is in its central position. As a result, the solenoid valve EV can be fed from P2 via the left contact of the double bypass 8. When the second level is reached, i.e. when the additional water supply is finished, the contact of P2 is switched to the right and the "full" signal can reach P.

In this particular case, the cam C2 is of course in the position shown in the figure, because the heater RR does not have to be switched on during the additional water supply to reduce the temperature of the suds in the tub.

If, on the other hand, the liquor must be heated to a temperature higher than 60ºC, the cam C2 is in the left position, while the right contact of the two bypasses 8 practically allows the thermostat PM1 to be bypassed.

This activates only the thermostat TM2 to power the heater RR and reach the set temperature exceeding 60ºC.

Basically, the right contact of the two bypasses 8 allows temperatures above 60ºC to be reached, while the left contact of the two bypasses 8 and the cam C3 allow the additional water supply at room temperature only if a correspondingly higher temperature is set and the cam C1 is in its central position.

Features and advantages of the invention have become clear from the foregoing description.

The invention provides in particular a washing machine comprising a manual control (button 8) which must be pressed by the user to enable the selection of a temperature higher than the preset limit. This button forces the user to make an unequivocal conscious choice of the water temperature to be used. This button is also associated with the important function of enabling an additional water supply to lower the liquid temperature in the tub only when necessary, i.e. when a high washing temperature is set, which allows considerable savings compared to the prior art.

All this can be achieved by very simple and inexpensive means, which, as described above, consist of the two bypass circuits, an additional cam for the electromechanical program selector switch and a few circuit changes.

It is obvious that, within the scope of the inventive concept, many possible modifications to the washing machines described as examples are available to the person skilled in the art.

As an example, the possibility of the button 8 (with the associated double diverter) and the selector switch 7 being coupled purely mechanically with means that also influence the selection of a temperature above 60ºC when the button 8 is pressed may be mentioned. The mechanical element may be, for example, a pin or a slider, which normally do not allow the knob 7 to be turned beyond the 60ºC position.

Then, when the button 8 is depressed, the pin or slider is retracted and the knob 7 can be rotated beyond the angular position of 60ºC. Furthermore, instead of the button 8 and the above-mentioned pin, a temperature selector switch with a knob having two different axial operating positions can also be used. Such a selector switch is shown in Fig. 3, the knob being designated 7A.

In this case, if the knob 7A is in its normal axial position (part A of Fig. 3), only a temperature up to 60ºC can be selected, while if the knob 7A is pushed out (part B of Fig. 3), a temperature above 60ºC can be selected.

In Fig. 3, reference numeral 20 indicates the temperature selection element, which is known as such, as a whole. 21 indicates a shaft which enables the selection of the desired temperature by means of the button 7A. 22 indicates a moving element with two stable end positions which enables the shaft 21 to assume two different axial positions, as can be clearly seen by comparing part A and part B of Fig. 3. This moving element 22 enables the button 7A to assume the two operating positions indicated. The moving element 22, which comprises, for example, a movable element with inclined planes and a spiral spring, is known as such (generally referred to as a snap-in push button) and is widely used in known washing machines.

Of course, in the embodiment shown in Fig. 3, apart from the circuit changes already described with reference to Fig. 2, the functions of the button 8 and the associated double bypass circuit could be integrated into the temperature selector switch 20. It is obvious that the double bypass circuit shown in Fig. 2 can be coupled to the shaft 21 in order to assume both working positions depending on the axial position of the button 7A.

Finally, it is obvious that the basic idea of the invention can, if necessary, also be applied to dishwashers, provided that they offer the possibility of manual temperature selection. The invention can also be applied in a case opposite to that described here as an example, i.e. in the case where a clear action by the user to select a temperature below a prescribed limit is desired; in this case, the key 8 or the button 7A can have the function of making it impossible to add a larger quantity of water.

Claims (14)

1. Washing machine, in particular laundry washing machine (1) comprising: - a washing cycle program device (6, C1, C2, C3), a selection device (20) for selecting a washing temperature from a plurality of selectable temperatures, - first means (P1, P2, EV) to control the water supply to the machine, and - second means (TM1, TM2, RR) to control the heating of the supplied water, wherein the first means (P1, P2, EV) and the second means (TM1, TM2, RR) are controlled by the program device (6, C1, C2, C3) in order to adequately achieve the water supply and the heating of the water, characterized in that manual control means (7A; 8) are provided, which, only when actuated by the user, serve to: - the operation of the second means (TM1, TM2, RR) is influenced to enable the water to be heated to a temperature within a certain temperature range from the selectable temperatures, the temperature being preset by the selection device (20), and - the operation of the first means (P1, P2, EV) is influenced to obtain the supply of a quantity of water which differs from the quantity of water which is usually supplied when a temperature which is not included in the predetermined temperature range is set. 2. Washing machine according to claim 1, characterized in that the predetermined temperature range is substantially between 60ºC and 95ºC and that in the case of actuation of the manual control means (7A; 8), the first control means (P1, P2, EV) Allow the introduction of a complementary quantity of water in addition to the quantity of water normally supplied, the complementary quantity of water being introduced in particular before a discharge step of the water used during a washing cycle. 3. Washing machine according to at least one of the preceding claims, characterized in that the manual control means (7A; 8) interact with corresponding electrical switching means. 4. Washing machine according to at least one of the preceding claims, characterized in that mechanical means (21, 22) are provided to prevent the selection of a temperature which is within a predetermined temperature range when the manual control means (7A; 8) are not actuated. 5. Washing machine according to claim 1, characterized in that the manual control means (7A; 8) are contained in the selection device (20). 6. Washing machine according to the preceding claim, characterized in that the manual control means (7A; 8) contain the button (7A) of the selection device (20) which can assume two different axial operating positions. 7. Washing machine according to claim 1, characterized in that the first control means contain a first pressure level switch (P1), a second pressure level switch (P2) and a solenoid valve (EV). 8. Washing machine according to claim 1, characterized in that the second control means include a water heating device (RR), a first thermostat (TM2) for controlling the water temperature within the predetermined temperature range and a second thermostat (TM1) for controlling the water temperature within another temperature range. 9. Washing machine according to claim 3 and 7, characterized in that the electrical circuit means contain a deviator device which is connected in the line which connects an electrical contact associated with the first pressure level switch (P1) to an electrical contact associated with the second pressure level switch (P2). 10. Washing machine according to claims 3 and 8, characterized in that the electrical circuit means comprise a deviator device which is connected to the line which establishes the connection to the contact of a cam (C2) which enables the water heating with the first thermostat (TM2), the deviator device in particular enabling the second thermostat (TM1) to be bypassed. 11. Washing machine according to claim 9 and 10, characterized in that the deviator devices are connected to one another so that they are actuated simultaneously in the event of actuation of the manual control means (7A; 8). 12. Washing machine according to claim 6 and 11, characterized in that the deviator devices interact with a button shaft (7A) of the selection device (20). 13. Control method for a washing machine, which includes all the elements known for its operation, among which are a washing cycle programmer (6, C1, C2, C3), a washing temperature selector (20), means (P1, P2, EV) for implementing the water supply to the machine and means (TM1, TM2, RR) for heating the supplied water, characterized in that - the reaching of a washing water temperature which has been selected by the selector device (20) from the selectable temperatures and is contained in a predetermined temperature range is influenced by the operation of the control means (7A; 8), and that - the actuation of the control means (7A; 8) presets the machine to supply a quantity of water which is different from the quantity of water which is usually supplied should a temperature which is not included in the predetermined temperature range be selected. 14. Control method according to claim 13, characterized in that the actuation of the control means (7A; 8) enables the heating of the water to a temperature selected by the selection device (20) and which is higher than a preset threshold value (60ºC) and as a result allows the supply of an additional quantity of water in addition to the corresponding quantity of water usually supplied when a temperature equal to or lower than the threshold value (60ºC) is selected, the additional supply of water having the purpose of reducing the temperature of the water previously supplied and heated by the machine.