METHOD FOR HEATING WATER AND AIR IN A WASH CYCLE, PARTICULARLY FOR DISHWASHERS, RESISTANCE ELEMENT TO CARRY OUT THE METHOD AND DISHWASHER IMPLEMENTING THE METHOD

Abstract: A method for heating water and air in a wash cycle, particularly for dishwashers (2), characterised by heating a thermoconducting wall (1) of the dishwasher from the outside by irradiation.

Description: METHOD FOR HEATING WATER AND AIR IN A WASH CYCLE, PARTICULARLY FOR DISHWASHERS, RESISTANCE ELEMENT TO CARRY OUT THE METHOD AND DISHWASHER IMPLEMENTING THE METHOD This invention relates to a method for heating water and air in a wash cycle, particularly for dishwashers, a resistance element to carry out the method and a dishwasher for implementing the method. In known household electrical appliances (washing machines) which during their operating cycle comprise a wash stage with previously heated water, this heating is achieved by a resistance element housed on the appliance base. During the wash stage the water is circulated by an appropriate spray circuit to be raised to the correct temperature by contact with the resistance element. During drying, current is passed through the resistance element a number of times for short periods to heat the air and hence dry the crockery. In a first arrangement a traditional armoured resistance element visible on the appliance base is used. This arrangement has however certain drawbacks, and in particular: - an unpleasant appearance due to the visible resistance element, - a reduction in available space due to the presence of this resistance element, - possible water leakage at the points at which the resistance element is fixed to the dishwasher base, - corrosion of the resistance element cladding following contact with detergents, - during drying, possible damage to plastic crockery and containers positioned in the vicinity of the resistance element, - the need for reliable safety devices (thermostats, timers) which control the resistance operates only for a prefixed time during the drying since lacking of water could cause irreversible damages to the same resistance. In another type of arrangement, the water is heated by passing it through a steel or plastic tube provided internally with a resistance element. However this system does not enable the drying stage to be effected unless additional element are used, such as a cold condensation wall or a conduit through the air is drawn during drying. The additional elements are costly, their cost being added to the high cost of the heating tube. All these drawbacks are eliminated according to the invention by a method for heating water and air in a wash cycle, particularly for dishwashers as described in claim 1. To carry out the method the invention foresees a resistance element as described in claim 5. The invention also relates to a dishwasher implementing the method. The present invention is further clarified hereinafter with reference to the accompanying drawings, in which: Figure 1 is a schematic bottom section of a dishwasher provided with the heating element; Figure 2 is a cross-section therethrough; and Figure 3 is a cross-section of a different embodiment. As can be seen from the drawings, in the method of the invention a box casing 3 defining a substantially parallelepiped compartment 4 is applied to the outside of the base 1 which is thermoconducting of a dishwasher 2. Inside said compartment 4 there is mounted a reflector 5, preferably of aluminium construction and supporting ceramic supports 6 for two heating elements formed from superposed resistive wires 7,7' adsorbing different powers. Each resistance wire 7,7' is connected to a thermostat 8 positioned in contact with the base 1. The heating element is used in the same manner as traditional resistance elements for dishwashers. During the wash stage the lower resistance element 7 of greater absorbed power (1800-2000 W) is activated to, when hot, irradiate the base 1 of the dishwasher 2, so heating the water contained in it at the predetermined temperature. During the drying stage the upper resistance element 7' (of 50-200 W absorbed power) is activated for a certain time period to cause the moisture contained within the dishwasher to condense and achieve drying of the crockery contained in it. The invention has been described with reference to a bare-wire resistance element, but the method can also be implemented with armoured resistance elements, halogen lamps, quartz tubes with an inner resistive wire, and any other resistance element able to radiate heat. From the aforegoing it is apparent that the method of the invention has numerous advantages, and in particular: - it eliminates the drawbacks of large space requirement and unpleasant outer appearance of armoured resistance elements positioned within the dishwasher, - it is of low cost because of the elimination of costly elements (heating tube and ventilation system). In the embodiment shows in Figure 3 the resistance consists of a cylindrical body 9, closed at the upper part, made of ceramic fibres, covered by a metal layer 10, and housing a resistance wire 11. Like in the previous embodiment, the body 5 is housed in a box casing 3. This embodiment presents the further advantage of not requiring the operating of the resistance during drying since the same heat is used accumulated by the body 9 during the heating of the water. In the illustrated embodiments the resistance element has been shown placed under the bottom of the dishwasher but it is also possible to place the resistence element outside a thermoconductive wall of the dishwsher which during the wash stage is lapped by the sprayed water.

Claims: C L A I M S 1. A method for heating water and air in a wash cycle, particularly for dishwashers, characterised by heating a thermoconducting wall of the dishwasher from the outside by irradiation. 2. A method as claimed in claim 1 , characterised in that the heating is carried out through at least a resistance element. 3. A method as claimed in claim 2, characterised in that two resistance elements absorbing different power are used. 4. A method as claimed in claim 1 , characterised in that the power absorbed during the water heating stage is greater than the power absorbed during the air heating stage. 5. A resistance element for implementing the method claimed in claims 1 to 4, characterised by consisting of a resistor (7,7') positioned external to a thermoconducting wall (1 ) of the dishwasher (2). 6. A resistance element as claimed in claim 5, characterised by consisting of a resistive wire. 7. A resistance element as claimed in claim 5, characterised by consisting of an armoured resistance element. 8. A resistance element as claimed in claim 5, characterised by consisting of a halogen lamp. 9. A resistance element as claimed in claim 5, characterised by consisting of a quartz/ceramic tube. 10. A resistance element as claimed in claim 5, characterised by being positioned within an aluminium reflector (5) with its reflecting surface facing the thermoconducting wall of the dishwasher. 11. A resistance element as claimed in claim 5, characterised by being housed within an upperly open box casing (3) fixed to the dishwasher base. 12. A resistance element as claimed in claim 5 characterised in that it consists of a cylindrical body (9) closed at the lower part, made of thermoinsulanting material and housing a resistance wire (11 ). 13. A dishwasher implementing the method according to any of claims 1 to 4 characterised in that it comprises a resistance element according to any of claims 5 to 12.

Inventors: CAPRARO DUILIO, COLOMBO ROBERTO, CAPRARO, DUILIO, COLOMBO, ROBERTO
Applicants: CAPRARO DUILIO, COLOMBO ROBERTO, I R C A S P A INDUSTRA, CAPRARO, DUILIO, COLOMBO, ROBERTO, I.R.C.A. S.P.A. - INDUSTRA
Application year: 1997
Main classification: A47L15
IPC codes: A47L15, D06F39