GB2271503A

GB2271503A - Dishwasher with heat exchanger

Info

Publication number: GB2271503A
Application number: GB9221828A
Authority: GB
Inventors: Oglio Erminio Dall
Original assignee: Hoonved SpA
Current assignee: Hoonved SpA
Priority date: 1992-10-16
Filing date: 1992-10-16
Publication date: 1994-04-20
Anticipated expiration: 2012-10-16
Also published as: GB2271503B; GB9221828D0

Abstract

A washing machine eg a dishwasher (10) comprises a tank (11) for containing dishes in which are present nozzles (12, 13) for the emission of water sprays. Said nozzles are selectively interconnected by exchange means (14) to an electric water heater (17) and to a water recycling system (16, 19, 20, 21, 22) sucking water from the bottom of the tank. The water recycling system comprises an element (20) for heat exchange with the water being heated with said water heater (17). Element (20) is in the form of a coil immersed in the chamber containing the water heated in the water heater. In this manner the water running in the recycling system is kept hot. <IMAGE>

Description

WASHING MACHINE In the washing machine art, e.g. the fast cycle type used in bars or the like for washing dishes, machines are known in which a first phase of washing is performed by sending into the tank hot water taken from an electric water heater and a second washing phase by recycling of the hot water present in the tank.

A problem with this procedure is that in the recycling phase the water temperature tends to fall progressively.

In addition, to reduce water consumption there is a tendency to retain the rinse: water in the tank for use subsequently as washing water. Thus there have been proposed dish washing machines in which in the tank is placed an electric heating resistance so that during the recycling phase, whether with water from the water heater or water retained from the previous washing cycle, the water is held at a temperature not lower than a predetermined limit.

A machine embodied in this manner is naturally costly since it is necessary to provide, in addition to the electric circuits for operation of the water heater, the electric circuits, including an armoured electric resistance, for heating of the water in the tank. In addition, such an embodiment suffers from the shortcoming that it has very high electrical consumption since simultaneous operation of the water heater and the electric resistance in the tank must be provided.

In accordance with an aspect of the present invention there is provided a washing machine comprising a tank for containing items to be washed and water emission means located within the tank, the water emission means being selectively connectable to receive water either from a water heater or from a water recycling system arranged to recycle water received from the tank, the water recycling system comprising heat exchange means arranged to exchange heat between water in the water heater and water in the recycling system.

It will thus be apparent that embodiments of the present invention may overcome shortcomings of the prior art by supplying a dish washing machine in which the recycled water is kept hot without having to provide an additional electric heating resistance.

To clarify the explanation of the principles of the present invention and the advantages which may be achieved compared with the known art there is described below with the aid of the single annexed diagrammatic drawing a possible embodiment by way of non limiting example applying said principles. With reference to the figure a dish washing machine 10 comprises a tank 11 in which are placed rotating arms 12 and 13 for emission of water sprays in accordance with the known art. Again in accordance with the known art in the tank there can be contained baskets for support of dishes to be washed, not shown because known to those skilled in the art.

To the rotating arms is connected the outlet of an electrically controlled selection valve 14 which can alternately connect thereto a duct 15 or a dtlct 16 for feeding water from an electric water heater 17 fed frm a water source 18 or from an element for heat exchange with the water heated by the water heater. For example, said exchange element can be made with a coil 20 immersed in the chamber containing the water heated in the water heater 17.

The exchange element 20 receives in turn the water from a duct 19 outlet from a pump 21 sucking from an intake 22 on the bottom of the tank 11.

The tank 11 also comprises a drain 23 for emission into a drain duct 24 through an electrically controlled valve 25.

A programming device 26 controls operation of the pump 21, of the exchange solenoid valve 14 and the solenoid drain valve in accordance with a predetermined programme of which an embodiment is described below by way of example.

The programming unit, which may be electronic or electromechanical, is substantially of the known art and therefore is not further described nor shown, as are not further described nor shown all those various elements of the known art such as for example detergent dispensers, level gauges, thermostats, etc., naturally present in dish washing machines and readily imaginable to those skilled in the art.

In a possible exemplary washing cycle, there is performed initially a phase of taking hot water from the water heater, which is connected to the ars 12 and 13 by the exchange valve 14. The pressure of the water sprayed by the nozzles located on the arms causes the arms to rotate and spray the dishes to be washed. When a predetermined quantity of water has been input to the tank the control circuit 26 switches the exchange valve 14 to interrupt the flow of water from the water heater and connect to the arms the delivery of the pump 21. Said pump is then activated to recycle the water collected on the bottom of the tank. At the same time there can be let into the tank a measure of detergent. The circulating water traverses continuously the exchanger 20 and thus remains hot during the cycle.After a predetermined time the control system 26 activates the drain solenoid valve 25 to evacuate the dirty water from the machine. The sequence described can again be performed with clean water from the water heater to perform rinsing of the dishes.

It can also be provided that, in case of lashings following each other in a short time, the rinse water which collects on the bottom of the tank is not evacuated but used, with the addition of detergent, for the following washing cycle, avoiding or reducing taking of new hot water from the water heater. In this case the water is returned to its temperature by recycling in the exchanger.

At this point the advantages secured by embodiments of the present invention compared with the known art are clear.

With limited cost, due mainly to the addition of a heat exchanger, water is kept hot in the recycling phase with a ninial energy expenditure.

Naturally the above description of an embodiment applying the innovative principles of the present invention is given merely by way of example and therefore is not to be taken as a limitation of the patent right claimed here.

For example, those skilled in the art. can readily imagine washing cycles different from that described and borrowed from known washing cycles for which the machine is fully suited.

In addition, it can be imagined to place the heat exchanger not directly inside the hot water chamber but in an adjoining chamber for containing water heated thereby.

Finally, the exchange valve can be made with two normal solenoid valves connected at the cutlet to the spray arms through a T joint.

Claims

1. A washing machine comprising a tank for containing items to be washed and water emission means located within the tank, the water emission means being selectively connectable to receive water either from a water heater or from a water recycling system arranged to recycle water received from the tank, the water recycling system comprising heat exchange means arranged to exchange heat between water in the water heater and water in the recycling system.

2. A machine according to claim 1 for washing dishes or glasses.

3. A machine according to claim 1 or 2 wherein the heat exchange means comprises a coil in a chamber for containing water heated by the water heater, the coil arranged to be immersed in the heated water.

4. A machine according to claim 1 or 2 wherein the heat exchange element comprises a coil inside the water heater.

5. A machine according to any one of the preceding claims, the water recycling system being arranged to suck water from the bottom of the tank.

6. A machine according to claim 5 wherein the water recycling system comprises a recycling pump with a suction end connected to the tank bottom.

7. A machine according to any one of the preceding claims wherein the water emission means comprises nozzles.

8. A machine according to claim 7 wherein the nozzles are supported by rotating arms.

9. A machine according to any one of the preceding claims comprising a solenoid selection valve for selectively connecting the water emission means to either the water heater or to the water recycling system.

10. A washing machine substantially as hereinbefore described with reference to the accompanying drawing