GB2192532A - Glass or dish washing machine - Google Patents

Abstract

A glass or dish washing machine comprises washing cabinet 1 with door 2, tank 4 having electric water heater 5, and pump 6 and spray devices 11, 12 for spraying washing and from rinsing water. A water discharge pump 19 is connected to outlet 9 of tank 4, which has a filter 23. Pressure-operated switches 28 and 29 actuated by air pressure in air trap 26 and an electronic controller are provided. Initially solenoid valve 15 is opened to allow water to flow into tank 4 through devices 11 and 12 to lower level L1. It is then closed on actuation of switch 28. Following heating of the water, pump 6 is operated for a predetermined time to effect washing. Valve 15 is then opened to effect rinsing. When the water level in tank 4 reaches higher level L2 switch 29 is actuated to start discharge pump 19. When the water level in tank 4 has dropped again to lower level L1, operation of pump 19 is stopped. The electronic controller is arranged to close valve 15 and stop pump 6 while maintaining pump 19 in operation to empty the tank after a predetermined number of wash and rinse cycles, or when the machine has been otherwise turned off. <IMAGE>

Description

SPECIFICATION Glass or dish washing machine This invention relates to glasswashing or dishwashing machines of the commercial cabinet type. Machines of this type comprise a washing cabinet for holding the articles to be washed, a loading door to enable the articles to be loaded into the cabinet, a tank in the bottom of the cabinet below the level of the loading door, the tank being capable of holding the whole volume of washing liquid and part of the rinsing water used in a cycle of washing operations, an electrical heater for heating washing liquid in the tank and a spray mechanism including a spray pump for supplying washing water to the tank and spraying washing water from the tank over the articles in the cabinet and subsequently spraying rinsing water from an external supply over the articles.

Generally the cycle of washing operations of such machines lasts only for about two minutes and consists only of spraying washing liquid over the glasses or other items, such as dishes or cups, and then rinsing the washing liquid from the items by spraying them with clean water.

In distinction from domestic dish washing machines, in which the cycle of washing operations lasts for 20-30 minutes and in which washing liquid is used on only a single batch of articles washed in a single cycle of operations of the machine and is then discharged, in the commercial machines with which the present invention is concerned the washing liquid and part of the rinsing water accumulates in the tank and is used a number of times on different batches of articles. After a cycle of washing operations, a volume of liquid equal to that of the rinsing water which is accumulated in the tank is removed from the tank and the remaining liquid, which is partly used washing water and partly cleaner rinsing water is used again in the next washing cycle.Since the washing water and the rinsing water are electrically heated before they are sprayed over the articles being washed, the re-use of the washing liquid and of part of the rinsing water results in a great saving of electricity and therefore in a great saving in cost.

Usually in machines of the commercial cabinet type, the water removed from the tank after a cycle of washing operations is drained out under gravity. As the waste outlet is near to the base of the machine this makes it impractical to position the machine on the floor because there is insufficient fall for the waste.

The gravity discharge of the water from the tank has usually been effected by means of a removable standpipe within the tank. The standpipe has an open top situated at the level of the surface of the liquid which is required to remain in the tank after a cycle of washing operations. That is to say the top of the standpipe is situated at a level which enables the tank to hold the required volume of washing liquid. When rinsing takes place, the additional water added to the tank overflows into the standpipe. When it is required to drain the tank completely to enable entirely fresh washing liquid to be used, the standpipe is removed manually and the liquid in the tank drains out through the opening in the bottom of the tank in which the standpipe was fitted.

When the tank is drained in this way, any dirt or debris from the washed glasses is washed straight down the gravity drainpipe into the drainage system.

Since the emptying of the tank and subsequently its refilling with clean water is controlled entirely manually by an operator of the machine, there is no restriction upon the number of times that the washing water, albeit partly diluted with cleaner rinsing water, may be used. If the operator is careless or not too punctilious, the water may be used too many times with consequent lack of hygiene.

The aim of the present invention is to overcome the problems described above and especially that of hygiene to improve the hygienic standards of the articles washed in the machine. The invention also improves the versatility of the machine in respect of the iocations in which it can be fitted by removing the restraints caused by gravity drainage of the tank.

To this end, according to this invention, a dish or glasswashing machine of the commercial cabinet type as initially described is characterised by an electrically driven water discharge pump having an inlet connected to a water outlet opening fitted with a filter in the bottom of the tank, an electrically operated valve for controlling the flow of washing water into the tank through the spray mechanism and an electrical controller which includes a device sensitive to the water level in the tank and which closes the electrically operated valve and sets the spray pump in operation for a predetermined time when washing water has flowed into the tank to a lower predetermined level, sets the discharge pump in operation when the addition of rinsing water has raised the water in the tank to a higher predetermined level, stops the discharge pump when the water level has dropped from the higher predetermined level to the lower predetermined level and closes the electrically operated valve and stops the spray pump whilst maintaining the water discharge pump in operation to empty the tank after a predetermined number of washing and rinsing cycles of operation, or when the machine has been otherwise turned off.

Because of the automatic control of the emptying of the tank, it is no longer possible to continue to use the same washing water for an unlimited time. Also, because of the addition of the discharge pump, and by the connection of the discharge pump bv means of a hose to an existing wastepipe, the machine is able to be fitted wherever it may be required.

In one example, the water level sensing device is a pressure-operated switching device and this may comprise two pressure switches which are connected by a common duct to an air trap within the tank below the predetermined lower level. As the water level in the tank rises to the predetermined lower level, the air in the duct leading from the air trap to the switches increases in pressure and when the lower predetermined level is reached, the first pressure switch is operated to cause the controller initially to close the electrically operated valve and subsequently to stop the water discharge pump. When the pressure in the duct increases further as the water level rises, the second switch is operated to cause the controller to start the water discharge pump when the higher predetermined level is reached.

In another example, the water level sensing device incorporates electrical conductivity sensors located one at each of the predetermined levels.

It is essential that the filter shall always be in position when the water discharge pump is operated as otherwise dirt or other debris washed from the glasses may clog the pump and damage the pump or its driving motor.

Preferably therefore the filter is fixed in position, but it must nevertheless be easy to clean by the operator of the machine. For this purpose the filter is preferably fitted with its upper surface substantially flush with the bottom of the tank so that it can be wiped over and cleaned with a cloth when the tank is emptied.

An example of a glass or dishwashing machine of the commercial cabinet type in accordance with the invention will now be described with reference to the accompanying drawing which is a highly diagrammatic perspective view of the machine as seen from the front and one side.

The machine comprises a cabinet 1, which is only shown in chain-dotted lines to enable internal details to be shown diagrammatically.

The cabinet 1 has a bottom-hinged door 2 and internal runners supporting a wire basket indicated at 3 holding glasses or other soiled articles to be washed. Within the cabinet 1, below the level of the bottom of the door 2 is a tank 4. The tank 4 has an electrical immersion heater 5 for heating the water supplied to it and within the cabinet 1 below the bottom of the tank 4 is an electrically operated centrifugal water spraying pump 6 having an inlet pipe 7 connected to a first outlet 9 in the bottom of the tank 4. An outlet pipe 10 leads from the spraying pump 6 to a first spray device 11 just above the maximum water level in the tank 4 and a second spray device 12 mounted in the top of the cabinet 1. The spray devices 11 and 12 each comprise a number of rotary arms 13 fitted with spray nozzles spraying upwards and downwards respectively.

A further pipe 14 fitted with a solenoid valve 15 leads from the main water supply to a boiler 16 which is fitted with a second electric immersion heater 16a. Further pipes 17 and 18 lead to the spraying devices 11 and 12.

All of the parts of the machine so far described are conventional, but in addition to these conventional parts, the machine is provided with a centrifugal water discharge pump 19 which has an inlet pipe 20 connected to a second water outlet 22 in the bottom of the tank 4. The two water outlets 9 and 22 are fitted with individual filters, but a further filter 23, which has its upper surface flush with the bottom of the tank 4 extends over both of the outlets. An outlet pipe 24 from the discharge pump 19 leads to a water discharge hose 25 which, when the machine is in use, can be lead to a sink or other drain somewhere near the machine. The drain must be above the level of the top of the tank 4 to prevent gravity drainage taking place through the pump 19.

The tank 4 is provided near its bottom with an air trap 26, the closed top of which has a small-bore tube 27 leading to two pressureoperated switches 28 and 29.

The solenoid valve 15 together with the electrically operated pumps 6 and 19 and the pressure switches 28 and 29 are all connected in an electrical control circuit which includes an electronic controller which is not shown. The controller causes the machine to perform automatically a full and repeating cycle of washing operations and this cycle is as follows: (a) on switching on a main electrical supply to the machine, the controller opens the solenoid valve 15 allowing water to flow into the tank 4 through the spray devices 11 and 12 and the tank fills with water, to which washing liquid is then added, to a lower level L1.

When the water reaches this level, the pressure in the air trap 26 operates the first pressure switch 28 and this causes the controller to close the valve 15; (b) the immersion heaters 5 and 16a are switched on and the water in the tank 4 and in the boiler 16 is heated to predetermined temperatures; (c) The solenoid valve 15 remains shut, but the spray pump 6 is started. This causes heated water with washing liquid added to it to be sprayed over glasses or other articles placed in the basket 3 by the spraying devices 11 and 12.The pump 6 remains in operation for a predetermined time after which it is stopped; (d) the solenoid valve 15 is opened and water flows into the boiler 16 thus causing water in the boiler which has been previously heated by the immersion heater 16a to be supplied to the spraying devices 11 and 12 to rinse the glasses or other articles with clean rinsing water under mains pressure; (e) as the rinsing water drains into the tank 4, the water level in the tank rises to a higher level L2 and when it reaches this level the increased pressure in the air trap 26 closes the second pressure-operated switch 29. This causes the electronic controller to start the water discharge pump 19 which pumps water out of the tank 4 faster than it flows in through the spraying devices 11 and 12; (f) when the water level in the tank 4 has fallen again to the level L1 the controller stops the pump 19.

Operations (e) and (f) are then repeated as necessary until the entire rinsing operation has been completed. This may be controlled on a time basis by the electronic controller.

To ensure that the hygiene of the machine is maintained, the electronic controller is arranged to maintain the water discharge pump in operation at the end of operation (e) to empty the tank completely after a predetermined number of full cycles of washing operations have taken place. This may also be arranged to happen after the machine has otherwise been turned off. The machine is thus emptied at the end of a washing session and it is ensured that each new washing session starts with clean washing water in the tank 4 with washing liquid added to it. This cannot be ensured with conventional machines because it is left to the discretion of the operator to drain the tank by the manual removal of a standpipe.

Since the filter 23 is flush with the bottom of the tank 4, it can, as already mentioned, easily be wiped over and cleaned with a cloth when the tank 4 is empty.

Claims (5)

1. A glass washing or dish washing machine of the commercial cabinet type comprising a washing cabinet for holding the articles to be washed, a loading door to enable the articles to be loaded into the cabinet, a tank in the bottom of the cabinet below the level of the loading door, the tank being capable of holding the whole volume of washing liquid and part of the rinsing water used in a cycle of washing operations, an electrical heater for heating washing liquid in the tank and a spray mechanism including a spray pump for supplying washing water to the tank and spraying washing water from the tank over the articles in the cabinet and subsequently spraying rinsing water from an external supply over the articles, characterised by an electrically driven water discharge pump having an inlet connected to a water outlet opening fitted with a filter in the bottom of the tank, an electrically operated valve for controlling the flow of washing water into the tank through the spray mechanism and an electrical controller which includes a sensing device sensitive to the water level in the tank and which closes the electrically operated valve and sets the spray pump in operation for a predetermined time when washing water has flowed into the tank to a lower predetermined level, sets the discharge pump in operation when the addition of rinsing water has raised the water in the tank to a higher predetermined level, stops the discharge pump when the water level has dropped from the higher predetermined level to the lower predetermined level and closes the electrically operated valve and stops the spray pump whilst maintaining the water discharge pump in operation to empty the tank after a predetermined number of washing and rinsing cycles of operation, or when the machine has been otherwise turned off.

2. A machine according to Claim 1, in which the water level sensing device is a pressure-operated switching device.

3. A machine according to Claim 2 in which the pressure-operated switching device comprises two pressure switches which are connected by a common duct to an air trap within the tank below the lower predetermined level, a first one of the pressure switches being operated to cause the controller initially to close the electrically operated valve and subsequently to stop the water discharge pump when the lower predetermined level is reached and the second switch being operated to cause the controller to start the water discharge pump when the higher predetermined level is reached.

4. A machine according to any one of Claims 1 to 3, in which the filter is fixed in position in the tank with its upper surface substantially flush with the bottom of the tank.

5. A machine according to Claim 1, substantially as described with reference to the accompanying drawing.