Washing machine with improved temperature selector

Abstract: A washing machine, is described, specifically a laundry washer (1), comprising a wash cycle programmer (6) and a device (7) to select a washing temperature among a plurality of selectable temperatures. According to the invention, the achievement of a washing water temperature selected by said selection device (6) and included in a determined temperature range (61°C-95°C) among the selectable temperatures (0°C-95°C) is affected by the actuation of manual control means (8), which also preset the machine to input a different quantity of water from the one supplied in should a temperature (0°C-95°C) not included in said determined temperature range (61°C-95°C) be selected.

Description: The present invention refers to a washing machine, specifically a laundry washer, as described in the preamble of the annexed Claim 1. It is known that most washing machines, specifically laundry washers, are equipped with a cycle programmer enabling the user to select a wash cycle among a plurality of selectable programs according to the characteristics of the clothes to be washed. Such a programmer, consisting mainly of an electromechanical cycle sequencer, controls adequately a number of devices located inside the machine, through which washing is executed. As known, such an electromechanical programmer comprises an electric motor entraining a cam pack for a preset time from the start to the end of a selected wash cycle. The cams profile is configurated in such a way to activate some electric contacts, which enable said internal devices at and for proper times. As a very schematic example, a first cam enables a solenoid-valve to take water in from the mains till a pressure-switch contact will stop water supply to said solenoid valve. A second cam activates a heater to heat the supplied water till a thermostat will detect achievement of a preset temperature. A third cam activates the motor rotation to cause the motion of the drum containing the laundry. A fourth cam activates a discharge pump to discharge the water used for the washing, and so on. The characteristics of said cam programmers are in any case known as such, so that a detailed explanation of their operation will not be needed for the purpose of the present description. It is also known that most washing machines, specifically laundry washers, are provided with a selector to choose the washing liquid temperature. Thus, through the knob of said selector the user can choose a desired temperature according to the kind of laundry to be washed, in a temperature field usually ranging from 0 °C to 95 °C. For instance, for the washing of delicate clothes the user will select a relatively low temperature (eg. 30°C), whereas to wash strongly and heavily soiled clothes the temperature will be decidedly higher, eg. 90 °C. If a temperature over 60 °C is selected, it is known to have a complementary supply of cold water before discharging the water used for a washing phase at a high temperature (eg. 90 °C). Such a complementary water supply usually occurring at the end of a hot washing step followed by a cold rinse has the purpose of preventing a thermal shock to the clothes, which would in fact happen in the passage from a high water temperature (water used for the washing step) to a very low one (water used for the rinse). Additionally, always with reference to the temperature that can be reached by the washing liquid, there are now special Standards in force in some countries requiring that washing machines shall not discharge into the sewer system any water with a temperature over a preset threshold, such a threshold being specifically about 60°C. It results from the above that when a user selects a temperature over 60°C in a washing machine the machine itself should reduce the water temperature down to said threshold before discharging the water at the end of the washing phase. This is practically obtained as described above, i.e. introducing a certain quantity of water into the machine wash-tub to reduce the temperature of the water already present. Thus, at the end of a washing phase in the strict sense and before starting water discharge, a cam of the cycle programmer enables a complementary supply of about 7 to 8 liters fresh water. Such a complementary water supply attenuating the temperature of the washing water, allows the water discharge according to the Standards and will prevent that cold water striking the hot laundry, so to avoid a thermal shock to the clothes. Said complementary fresh water supply is obtained through actuation of the contacts of a pressure switch, which usually provided (in the washing machines) is with two different levels, namely a first level for the normal washing phases and a second higher level in respect to the previous one, to allow input of more water for some specific phases of a wash cycle, as for instance the above complementary supply to attenuate the temperature of the washing liquid. As described above, it is obvious that in the case of wash cycles at temperatures below 60 °C, the complementary water supply to avoid a thermal shock and/or attenuate the temperature of water discharge is not needed and, as a result, when selecting such temperatures, also activation of the second level pressure-switch for complementary water supply is not necessarily required. However, in the machines with electromechanical cam programmer, where a special cam controls activation of the second level of the pressure switch, it is not such an easy task to prevent said complementary water supply. This is essentially due to space requirements related to the cam pack, where it would be rather complicated to provide more individual cams to exclude the second level of the pressure switch in case different temperatures are selected. Due to said reasons, washing machines equipped with an electromechanical cycle sequencer actually take in about 7/8 liters more water than strictly necessary. This obviously entrains a considerable waste. From EP-A-0225 550 a rotary switch apparatus for the cycle selection on a washing machine is known, wherein the temperature can only be selected within a certain range according to the type of fabric to be washed. It is the object of the present invention to solve this problem and provide, specifically, a washing machine capable of avoiding in a relatively simple and low-cost manner, a useless water wastage, so as to reduce the temperature of the liquid used during a washing step. In this frame, it is an additional object of the present invention to provide a washing machine where such a limiting function of water consumption is associated with a control element imposing the user to specifically decide about the washing temperature to be selected. According to the present invention, said objects are obtained by providing a washing machine, specifically a laundry washer, incorporating the features listed in the annexed claims, which summarize the learnings for the achievement of the present invention. The characteristics and advantages of the present invention will be apparent from the following description and annexed drawings, which are supplied only by way of an explanatory but not limiting example, wherein: Fig. 1 shows schematically a laundry washer according to the present invention; Fig. 2 shows a partial view of the simplified wiring diagram for the washing machine shown in Fig. 1; Fig. 3 shows a schematic section of a detail of a laundry washer according to a possible variant of the present invention. In Fig. 1 reference number 1 indicates a washing machine as a whole according to the present invention. Such a machine is for instance of the type mentioned at the beginning of the present description and is inclusive of all elements as known for its operation. Number 2 indicates the machine loading door and 3 its control panel. Such a control panel comprises a detergent dispenser indicated with number 4, an ON/OFF main switch indicated with 5 and the knob of an electromechanical cycle programmer indicated with 6, which enables selection of a wash cycle out of a plurality of selectable cycles having different characteristics. Panel 3 also comprises a second knob indicated with number 7, pertaining to a temperature selector for the washing liquid that the user can select out of a plurality of selectable temperatures. According to the known state of the art, the selectable temperature may for instance range from 0 °C to 95 °C. According to the present invention the panel 3 comprises additionally a double-function key indicated with number 8. When pressed down, this key 8 enables heating of the washing liquid at a washing temperature exceeding an imposed limit, which in the specific example is 60 °C. In other words, then, if the user wishes to wash at a temperature of 90 °C, this cannot be obtained without the depression key 8. Such a function is based on the fact that in the practice temperatures exceeding 60 °C may entail some damage risks for the clothes to be washed, since such temperatures are only suited for certain strong treatments and for those clothes capable of withstanding so high a temperature. To provide just a simple temperature selection knob may in fact lead to mistakes. Let us think for instance of a user introducing some delicate clothes in the machine and then rotating unintentionally the temperature knob well over the temperature degree such laundry pieces can withstand. According to the present invention the key 8 has a first significant function of sensibilizing the user when selecting a so-called 'dangerous' temperature, i.e. forcing the user to take a specific decision during said action (temperature selection). Moreover, according to the present invention, the key 8 has a second significant function. Specifically, said key 8 is associated with adequate circuit means enabling said complementary water supply only when said key 8 is pressed down, i.e. when a temperature range over 60 °C has been selected. Thus, practically, key 8 has the function of enabling the second pressure-switch level just to attenuate the temperature of the washing liquid in the instances already mentioned at the beginning of the present description, i.e. when actually required. This means that when the user selects a washing temperature ranging from 0 °C to 60 °C the machine will not take in a complementary supply of about 7 to 8 liters water; viceversa, said complementary water supply to attenuate the temperature of the liquid contained in the wash-tub will take place only when a temperature over 60 °C has been selected, i.e. only if key 8 has been pressed down. Therefore, this means that key 8 has a double action of sensibilizing and making the user aware that he wants to choose high washing temperatures and allow him at the same time to achieve a considerable water saving. Figure 2 shows only by way of example a portion of the simplified wiring diagram of the washing machine illustrated in fig. 1, limitatively to the portion related to the circuit means associated with key 8. Thus, this figure practically only shows the portion of a wiring diagram modified in respect to the known state of the art in a machine according to the present invention. Let us assume, therefore, that the remaining part of said wiring diagram is substantially similar to the one of the known machines. In said figure 2 EV indicates a solenoid valve for water supply into the machine, P1 indicates the electric contact of a first level pressure switch (i.e. a lower level) and P2 the electric contact of a second level pressure switch (i.e. a higher level). Contacts P1 and P2 are preferably enclosed in one pressure switch of the type suited to detect both different levels. The characteristics and operation of such a pressure switch will not be described in detail as they pertain to the same concept already known and applied in the practice to nearly all washing machines available in trade. RR indicates a heater to heat the washing water, whereas 8 indicates the above mentioned key enabling temperature selection over 60 °C. As it will be noticed, this key 8 is associated with a double deviator. C1 indicates a cam of the programmer or electromechanical timer 6 of the washing machine to enable the second level of the pressure switch in the relevant steps of the wash cycle, whenever required. Said cam C1 is a standard cam as normally used in the known programmers. C2 indicates a second cam, also normally used in the known programmers, which is provided to enable the washing liquid heater at the right time. C3 indicates a third cam whose function is to enable the second level of pressure switch P2 for the above mentioned complementary water supply. In the machines of known type, viceversa, the complementary water input is controlled through cam C1 with the consequent problems of water consumption as mentioned at the beginning of the present invention. Therefore, cam C3 according to the present invention is an additional cam in respect to the known state of art. Finally, TM1 and TM2 indicate two thermostats, respectively, to control heater RR. Thermostat TM1 enables/disables power to the heater RR within the temperature range from 0 °C to 60 °C, whereas thermostat TM2 enables/disables power to the heater RR within a temperature range from 61 °C to 95 °C. Operation of the circuit portion shown in figure 2 is as follows. Let us assume for instance that a user wants to operate the machine for a washing at a temperature up to 60 °C, under this condition the key 8 and its associated double deviator do not have to be pressed. Double deviator contacts are positioned as shown in the figure. The solenoid valve EV is fed by conductor L through contact P1, which is in the position shown in Fig. 2. When the first liquid level is reached, pressure swicht P1 commutates, i.e. its contact is moved to the position on the right shown in Fig. 2. During this step also cam C1 is positioned on the right and as a result the socalled 'full signal' of pressure switch P1 can proceed along conductor P to enable a subsequent wash cycle step through the timer 6 of Fig. 1 (eg. machine drum rotation). When the cycle provides liquid heating within the range up to 90 °C, cam C2 is moved to the left position, so the heater RR will be activated till the thermostat TM1 detects that the preset temperature for the washing liquid has been reached. As it can already be noticed from the figure, the thermostat TM2 to heat the liquid to temperatures over 60 °C will not start operating if the key 8 has not been pressed, since under this condition the washing liquid will never reach a temperature range over 60 °C. In case of a washing requiring the second liquid level even if the temperature reaches only 60 °C (eg. in the event of a washing program for special clothes requiring a higher volume of water, such as synthetics), cam C1 is moved to the left position in Fig. 2. Thus, when the first level is reached, the contact of P1 will move to the position on the right and the contact of P2 be enabled right through cam C1, so that the solenoid valve EV can be fed till the second level is reached. At this point P2 commutates, moving its contact to the position on the right in Fig. 2 and stop feeding to the solenoid valve. Also in this event the "full signal", i.e. reaching the preset liquid level, can go further towards P as described above. As said, key 8 has to be pressed to execute washing at a temperature over 60 °C. Let us assume, in this instance, that the liquid in the tub has already reached the first level and the contact of P1 is already in the position on the right. When said complementary liquid supply at room temperature is necessary during execution of a selected wash cycle to attenuate the temperature of the washing liquid in the tub, cam C1 is in its central rest position as shown in Fig. 2, cam C3 is on the left and cam C2 in the central position. As a result, the solenoid valve EV can be fed by P2 through the left contact of the double deviator 8; upon reaching the second level, i.e. when the complementary liquid supply is completed, the contact of P2 commutates to the right position and the 'full' signal can proceed towards P. Obviously, in this specific instance cam C2 will be in the position shown in the figure, since during the complementary water supply to attenuate liquid temperature inside the tub, activation of heater RR will not be required. Viceversa, when requesting liquid heating within a temperature range over 60 °C, the cam C2 will be on the left position and the right contact of the double deviator 8 can practically allow to by-pass the thermostat PM1. Thus, only the thermostat TM2 will be enabled, so as to supply the heater RR and reach the preset temperature over 60 °C. Substantially, the right contact of the double deviator 8 enables the achievement of temperatures over 60 °C, whereas the left contact of the double deviator 8 and the cam C3 enable the complementary water supply at room temperature only when such higher temperatures have been selected and provided that the cam C1 is on its central position. The characteristics and advantages of the present invention will be apparent from the above description. Specifically, according to the suggested invention, a washing machine is provided comprising a manual control element (key 8) that has to be pressed by the user to obtain the actual selection of a temperature over a preset limit. This key will then inequivocably forces the user to perform a conscious action of temperature selection for the water to be used. This key is also associated with the significant function of enabling a higher water supply to attenuate the temperature of the liquid inside the tub only in those instances where it is required, namely when high washing temperatures are selected, to obtain a considerable saving with respect to the known state of art. All this is obtained with very simple and low-cost means, which according to the above description consist of a double deviator, an additional cam to an electromechanical programmer and a few circuit changes. It is obvious that many changes to the washing machines described by way of example are possible for the man of the art, without departing from the novelty frames of the innovative idea. As an example it can be mentioned the possibility of associating key 8 (and associated double deviator) and selector 7 to means also affecting the temperature selection over 60 °C from a mechanical standpoint only when pressing key 8. Said mechanical means may for instance comprise a plug or a cursor that does not normally allow the angular motion of knob 7 over the position in line with 60 °C. Viceversa, when key 8 is pressed down such a plug or cursor is backdrawn, to allow rotation of the knob 7 over the angular position in line with 60 °C. Moreover, in-lieu of the key 8 and plug means mentioned above, it is also possible to use a temperature selector with a knob of the kind suited for two different operational axial positions. Such a selector type is shown in Fig. 3 where the knob is indicated with 7A. In such an instance, with the knob 7A in its normal axial position (part A, in Fig. 3) only the temperature selection up to 60 °C is allowed whereas with knob 7A extracted (part B, in fig. 3), temperatures over 60 °C can be selected. In Fig. 3, number 20 indicates as a whole the temperature selecting device, known as such; 21 indicates a shaft allowing selection of the desired temperature through knob 7A; 22 indicates a bi-stable kinematics motion allowing shaft 21 to take two different axial positions as clearly visible from a comparison between part A and part B of Fig. 3. Such a kinematics motion 22 allows knob 7A to take both operational positions as previously mentioned. Such a kinematics motion 22, comprising for instance a movable element with inclined planes and a spiral spring, is known as such (generally called push-push) and is largely used on existing washing machines. It is obvious that in the instance of the embodiment shown in Fig. 3, apart from the circuit changes already described with reference to Fig. 2, the functions of key 8 and of its associated double deviator could be incorporated in the temperature selector 20. As a matter of fact, it is apparent that the double deviator shown in Fig. 2 may be associated with the shaft 21 to take both work positions according to the axial position of knob 7A. Finally, it is obvious that the basic concept of the present invention can also be applied if necessary to dishwasher machines provided with possibility of manual temperature selection. Similarly, the invention can find application in a frame opposed to the one described herein by way of example, i.e. whenever a sure user's action for the selection of a temperature below an imposed limit is desired, in which case the key 8 or the knob 7A may have the function of disabling a higher water supply.

Claims: A washing machine, specifically a laundry washer (1), comprising a washing cycle programmer (6,C1,C2,C3), a selecting device (20) of a washing temperature among a plurality of selectable temperatures, first means (P1,P2,EV) to control the water supply in the machine, and second means (TM1, TM2, RR) to control the heating of the supplied water, said first means (P1,P2,EV) and said second means (TM1,TM2, RR) being controlled by said programmer (6,C1,C2,C3) to adequately achieve the water supply and its heating, characterized in that manual control means (7A;8) are provided which, only when actuated by the user, provides for: affecting the operation of said second means (TM1, TM2,RR) to enable the water heating at a temperature within a determined temperature range among the selectable temperatures , said temperature being preset through the selecting device (20), and affecting the operation of said first means (P1,P2,EV) to obtain the supply of a different water quantity with respect to the water quantity which is normally supplied in when a temperature not comprised in said determined temperature range is enabled. A washing machine, according to Claim 1, characterized in that said determined temperature range is substantially comprised between 60°C and 95°C and that in case of actuation of said manual control means (7A;8), said first control means (P1,P2,EV) enable a complementary water supply with respect to the one normally supplied, said complementary supply occurring in particular prior to a discharge step of the water used during a wash cycle. A washing machine, according to at least one of the previous Claims, characterized in that said manual control means (7A;8) are associated with respective electric circuit means. A washing machine, according to at least one of the previous Claims, characterized in that mechanical means (21,22) are provided to inhibit - when said manual control means (7A;8) are not actuated - the selection of a temperature comprised within said determined temperature range. A washing machine, according to Claim 1, characterized in that said manual control means (7A;8) are comprised in said selecting device (20). A washing machine, according to the previous Claim, characterized in that said manual control means (7A;8) comprise the knob (7A) of said selecting device (20), which can take two different axial operating positions. A washing machine, according to Claim 1, characterized in that said first control means comprise a first level pressure switch (P1), a second level pressure switch (P2) and a solenoid valve (EV). A washing machine, according to Claim 1, characterized in that said second control means comprise a water heater (RR), a first thermostat (TM2) for the control of the water temperature within said determined temperature range and a second thermostat (TM1) for the control of the water temperature within a different temperature range. A washing machine, according to Claims 3 and 7, characterized in that said electric circuit means comprise a deviator incorporated on the line which connects an electric contact associated with said first level pressure switch (P1) with an electric contact associated with said second level pressure switch (P2). A washing machine, according to Claims 3 and 8, characterized in that said electric circuit means comprise a deviator inserted on the line which connects the contact of a cam (C2) which enables the water heating with said first thermostat (TM2), said deviator allowing in particular to by-pass said second thermostat (TM1). A washing machine, according to Claims 9 and 10, characterized in that said deviators are interconnected, so that their actuation occurs simultaneously in case of actuation of said manual control means (7A;8). A washing machine, according to Claims 6 and 11, characterized in that said deviators are associated with a knob shaft (7A) of said selecting device (20). A control method for a washing machine of the kind comprising all the elements known for its operation, among which a wash cycle programmer (6,C1,C2,C3), a selecting device (20) of the washing temperature, means (P1,P2,EV) to realize the water supply in the machine and means (TM1,TM2,RR) to heat the supplied water, characterized in that the achievement of a washing water temperature selected through said selecting device (20) and comprised in a determined temperature range among the selectable temperatures is affected by the actuation of controls means (7A;8), and that the actuation of said control means (7A;8) also presets the machine to supply a water quantity being different with respect to the water quantity which is normally supplied should a temperature not included in said determined temperature range be selected. A control method, according to claim 13, characterized in that the actuation of said control means (7A;8) allows for heating of the water at a temperature, chosen through said selecting device (20), which is higher than a preset threshold (60°C), and enables as a result the supply of a water quantity being additional with respect to the water quantity which is normally supplied in the event a temperature equal or lower than said threshold (60°C) is selected, said additional water supply having the purpose of reducing the temperature of the water previously supplied and heated by the machine.

Inventors: MARIOTTI COSTANTINO, MARIOTTI, COSTANTINO
Applicants: MERLONI ELETTRODOMESTICI SPA, MERLONI ELETTRODOMESTICI S.P.A.
Application year: 1996
Main classification: D06F39
IPC codes: D06F39