Improved dishwashing machine

Abstract

 A dishwashing machine (110) comprises a tub (111) for containing dishes to be washed disposed on removable racks, said tub being fitted with rotary arms (112) fed by a pump (113) fed by a three way valve (114) connecting the pump alternatively to a water intake (115) disposed on the bottom of the tub (111) or, selectively, to two sources of water (117, 145).
Said dishwashing machine (110) also comprising a drainage outlet (119) with electric control (118) and a liquid detergent dispenser (120).
Lastly, a timer (121) sequentially controls the three-way valve (114), the pump (113), the dispenser (120) and the drain outlet electric control (118).

Description

[0001] This invention refers to an improved dishwashing machine.

[0002] There are known dishwashing machines in which it is possible to economize on water by using recirculated water for the washing phase with detergent. After which, clean water is introduced into the tub for the rinsing phase. The rinsing water is then discharged and the next washing cycle for a new load of dishes is started by introducing clean water into the tub of the dishwashing machine. By proceeding in this way it is possible to economize on water, especially when compared to the water consumption of machines which discharge continuously throughout the cycle. The consumption is even more considerable in the case of heavy-duty machines such as those used in bars and restaurants.

[0003] Moreover, for reasons of structural and dimensional economy, the rinsing cycle is usually carried out by introducing water from the mains without using a pump, but by simply using the natural pressure of the incoming water; this however leads to possible irregularities in the rinsing cycle due to pressure variations in the distribution system.

[0004] The scope of this invention is to obviate the aforementioned problems, as well as others which will be explained further on, by providing a dishwashing machine that reduces the water consumption even further, that has regular cycles regardless of the pressure of the mains and that permits the widest degree of flexibility in programming the washing cycles.

[0005] This scope is achieved by providing a dishwashing machine of the type comprising a programming device and a tub containing the dishes to be washed arranged on racks, which is provided with a plurality of water nozzles and the bottom of which is connected to a drain which is electrically controlled to open and close, and having a device for dispensing pre-established amounts of detergent in communication with the inside of the tub, characterized by the fact that said nozzles are connected to the delivery side of a pump whose suction inlet is connected to switching and on/off means electrically controlled by the timer and connecting said inlet, selectively, to a water intake which draws water from the bottom of said tub, to a first source of water or to a second source of water.

[0006] The innovatory principles of this invention and its advantages with respect to the known technique will be more clearly evident from the following description of a possible exemplificative embodiment applying such principles, with reference to the accompanying drawings, in which:

- figure 1 shows a schematic view of a dishwashing machine made according to the innovatory principles claimed herein;

- figure 2 shows a schematic phantom view of a valve unit used in the machine of figure 1;

- figure 3 shows a schematic plan view of the valve unit of figure 2;

- figure 4 shows a front elevation cross-sectional view along the line IV-IV- of figure 3;

- figure 5 shows a front elevation cross-sectional view along the line V-V of figure 3.

[0007] With reference to the figures, a dishwashing machine, generically indicated by reference 110 in figure 1, comprises a tub 111 containing one or more rotary spray arms 112.

[0008] Said rotary spray arms 112 are connected to the delivery side of a pump 113, the suction inlet of which is connected to the outlet of a switching and on/off unit 114 having a first solenoid valve controlled inlet 115 in communication with the bottom of the tub 111, a second solenoid valve-controlled inlet 116 in communication with the outlet of a storage tank in the form of an electric water heater 117 the inlet of which is connected by means of a pipe 128 to a water supply (not shown), and a third solenoid valve-controlled inlet 131 also connected to a water supply (not shown) by means of a pipe 146, advantageously fitted with a cistern 145 in order to make up for any possible insufficient delivery of water from the mains.

[0009] Also connected to the bottom of the tub 111 is an electric pump operated or solenoid valve-controlled discharge outlet 118 which leads off into a drain pipe 119 connected to a drainage system of the known type and therefore not shown.

[0010] An electrically-controlled dispenser 120 (for example solenoid valve or pump-controlled) containing detergent is disposed to introduce a pre-established quantity of detergent into the tub 111 each tme it is actuated.

[0011] The outlet 118 and the first solenoid valve-controlled inlet 115 of the unit 114 are protected against the entry of foreign bodies by means of filter elements 129, 130 respectively (for example, cages made of metal or other material).

[0012] Lastly, a timber 121 (for example, electromechanical) controls that the dishwashing cycles are carried out correctly.

[0013] The dishwashing machine obviously comprises other parts (such as, for example, removable racks for the dishes, thermostats, level gauges, drying means, etc.) which, being of known technique and consequently easily imaginable by anyone expert in the field, are not shown nor further described herein.

[0014] Although the switching and on/off unit 114 can be achieved by a suitable combination of solenoid valves of known technique (as is easily imaginable by anyone expert in the field, especially on the basis of the following descriptions) of the type which, upon actuation, opens in the presence of substantially zero pressures in the system, it was found advantageous to use an integrated device as is more clearly shown in the schematic phantom view of figure 2.

[0015] As can be seen in said figure, the unit 114 comprises an airtight casing 122 containing the aforementioned inlet connections 115, 116, 131 and the outlet 123.

[0016] Inside the casing 122 there are (as can be more clearly seen in figure 3) upper chambers 132, 133, 134, in correspondence with the inlets 115, 116 and 131 respectively, and a lower chamber 135 into which opens out the duct 123 (as can be seen in figures 2, 4 and 5).

[0017] Between the upper chambers 132, 133, 134 and the lower chamber 135 there are passages 136, 137, 138 respectively, with diaphragm valves 139, 140, 141, respectively, normally closed and made to open by means of solenoids 142, 143, 144 respectively.

[0018] A valve unit as described above enables the inlet ducts 115, 116, 131 to be selectively connected to the outlet duct 123 while occupying a minimum of space. It should be noted that the shutters 139, 140, 141 are disposed on the upstream side of the apertures 136, 137, 138 and the pressure of the water itself consequently helps to keep the deactivated solenoid passages closed.

[0019] The machine described above operates in the following way. After the dishes have been arranged on the racks disposed inside the tub 111 and the timer 121 has been started up, the latter will begin the washing cycle, controlling the activation of the various devices of the machine according to a pre-established sequence. Thanks to the presence of the device 114 and the aforesaid sequence can comprise introduction of cold water from the mains (through the cistern 145), hot water from the water-heater 117, recycled water from the bottom of the tub 111, or mixed combinations of these waters, into the tub.

[0020] In this way, as is easily imaginable by anyone expert in the field, it is possible to obtain a vast variety of washing cycles, each suitable for particular requirements in terms of hygiene, speed and efficiency.

[0021] One preferred washing cycle can comprise, for example, the three pre-washing, washing and rinsing phases and proceed as described below.

[0022] First there is the low-temperature pre-washing phase in which the timer, by means of the device 16, connects the ducts 131 and 116 to the pump 113 and activates the latter so as to mix the cold water from the cistern 145 with the hot water from the water-heater 117 and thus send warm water (for example, at a temperature no higher than 40°) to the rotary spray arms 112 which, under the pressure of the water itself, begin to rotate and sprinkle it around the inside of the tub.

[0023] After a given quantity of water has been sprayed, the control device 121 closes the inlets 116 and 131 and opens the inlet 115 so that the pre-washing phase continues with closed cycle circulation of water taken from the bottom of the tub and re-expelled by the rotary spray nozzles 112. The dispenser 120 is simultaneously actuated to release a dose of detergent into the tub.

[0024] After the water with detergent has recirculated for a given length of time, the device 114 returns to the rest position and the pump 113 is stopped while the water in the tub is discharged by actuating the outlet 118, so as to put the bottom of the tub in communication with the drainage system until the pre-washing water has been completely drained off.

[0025] Upon closure of the outlet 118, the control device 121 opens the inlet 116 from the water-heater 117 and starts up the pump 113 so as to send a pre-established quantity of hot water (for example, 65-70°) into the tub through the spray nozzles 112). The inlet 116 is closed and the inlet 115 is opened while the dispenser 120 is made to release a second dose of detergent into the tub so as to obtain a washing phase with recirculation of hot water.

[0026] After a pre-established length of time for the washing phase, the timer 121 causes the device 114 to return to the rest position and stops the pump 113 while the water is drained from the tub by actuation of the outlet 118.

[0027] Upon closure of the outlet 118, the control device 121 opens the inlet 116 from the water-heater 117 and starts up the pump so as to send a pre-established quantity of hot water into the tub through the spray nozzles 112 and consequently rinse the detergent from the dishes.

[0028] The quantity of water used during the rinsing phase remains on the bottom of the tub and can advantageously be used for the pre-washing phase of the following cycle with a new load of dishes.

[0029] For this purpose, at the start of the following washing cycle the timer 121 does not open the inlet 116 but only the inlet 131, so as to bring the water in the tub up to the right pre-washing temperature, and then carries out the pre-washing phase with recirculation of water, the washing and the rinsing phases, as previously described, and so on, always using rinsing water for the subsequent pre-wash, resulting in an obvious economy in the consumption of water.

[0030] Moreover, the fact of using the rinsing water (containing, therefore, a certain amount of residual detergent) makes it possible to use less detergent since it is only necessary to add the part of it discharged with the waste water of the previous wash.

[0031] The pump is advantageously activated after having opened the relative aperture in the device 114, so as to limit the force required by the opening electromagnet, and is deactivated before the aperture is closed so as to avoid possible cavitation of the pump.

[0032] With a machine made according to the invention, in addition to the advantages of saving a considerable amount of water and a certain amount of detergent, as well as the flexibility in obtaining possible washing cycles, there is also the advantage that the water is always introduced into the tub by means of a pump and therefore at constant pressure, regardless of the pressure of the mains and the delivery of the latter owing to the presence of the water-heater 117 and the cistern 145 acting as storage tanks between the mains and the tub. This ensures maximum efficiency at all times.

[0033] The use of the switching and on/off device shown in figures 2, 3, 4 and 5 in place of combinations of valves of known technique offers the further advantage of being able to limit the dimensions of the unit 114, so as to obtain, together with the presence of a single pump for recycling the washing and rinsing water, a machine of very limited dimensions in relation to its working load. Moreover, the device 114 makes it possible to save time and materials in constructing the machine by eliminating the necessary connections between the various solenoid valves of known technique.

[0034] The water-heater can advantageously be arranged with one non-insulated wall in contact with the bottom of the tub, so as to keep the water on the bottom of the tub warm by conduction.

[0035] The foregoing description of a dishwashing machine and a washing cycle related thereto is obviously given purely by way of example in order to illustrate the innovatory principles claimed herein and should not therefore be considered as a a limitation thereto.

[0036] For example, instead of being introduced directly into the tub, the detergent may be introduced at any desired point of the flow of water entering the tub, in particular, in the device 114. Moreover, in the event of the outlet 118 being controlled by a solenoid valve it is still possible to provide a pump downstream of the latter in order to help drain off the water from the tub.

[0037] Furthermore, the water spraying system inside the tub may be made according to any other method of known technique and not necessarily by means of rotary nozzles.

[0038] Lastly, the expert technician can imagine other cycles utilizing the innovatory features of this invention. For example, several ashing and pre-washing phases can be carried out by simply programming the opening times of the aperture 116 with respect to the aperture 131 so as to mix different proportions of hot and cold water.

Claims

1. A dishwashing machine of the type comprising a programming device and a tub containing the dishes to be washed arranged on racks, which is provided with a plurality of water nozzles and the bottom of which is connected to a drain which is electrically controlled to open and close, and having a device for dispensing pre-established amounts of detergent in communication with the inside of the tub, characterized by the fact that said nozzles are connected to the delivery side of a pump whose suction inlet is connected to switching and on/off means electrically controlled by the timer and connecting said inlet, selectively, to a water intake which draws water from the bottom of said tub, to a first source of water or to a second source of water.

2. Dishwashing machine as claimed in Claim 1, characterized by the fact that the first source comprises a storage tank in the form of an electric water-heater.

3. Dishwashing machine as claimed in Claim 1, characterized by the fact that the second source comprises a cold water storage tank.

4. Dishwashing machine as claimed in Claim 1, characterized by the fact that the drainage outlet, dispenser, pump and switching and on/off means are connected to a timer which, in a washing cycle, sequentially controls: the pump to supply water to the nozzles and presetting of the switching and on/off means for connection of the pump inlet to the water intake at the bottom of the tub and to the second source with simultaneous introduction of a pre-established dose of detergent into the flow of circulating water, in order to obtain a pre-washing phase with detergent for a pre-established length of time with closed-circuit circulation of water inside the tub; said electrically-controlled drainage outlet, until all the water has been drained from the inside of the tub; said pump to supply water to the nozzles and presetting of the switching and on/off means for connection of the pump inlet to the first source of water for emission of a pre-established quantity of water from said spray nozzles for a washing phase; the pump to supply water to the nozzles and presetting of the switching and on/off means for connection of the pump inlet to the water intake on the bottom of the tub with simultaneous emission of a pre-established dose of detergent into the flow of circulating water, in order to obtain a washing phase with detergent for a pre-established length of time with closed-circuit circulation of water inside the tub; said electrically controlled drainage outlet, until all the water has been drained from the inside of the tub; said pump to supply water to the nozzles and presetting of the switching and on/off means for connection of the pump inlet to the first source of water for emission of a pre-estalished quantity of water from said spray nozzles for a rinsing phase with the drainage outlet closed, so as to provide a subsequent supply of water on the bottom of the tub for the next washing cycle.

5. Dishwashing machine as claimed in Claim 4, characterized by the fact that said timer can be set to enable the pump and the switching and on/off means to withdraw a given quantity of water from the first and second source to be sprayed from the nozzles before the start of the washing cycle, so as to provide a subsequent supply of water on the bottom of the tub for the next washing cycle.

6. Dishwashing machine as claimed in Claim 1, characterized by the fact that the switching and on/off means are made in the form of an airtight casing containing first separate incoming chambers of inlet connections for connection to the first and second source of water and to the intake on the bottom of the tub, and a second outgoing chamber of an outlet connection for connection to the inlet of the pump, diaphragm on/off means being disposed between the first chambers and the second chamber, said on/off means being normally closed and made to open by solenoids and operatively connected to the timer.

7. Dishwashing machine as claimed in Claim 6, characterized by the fact that the diaphragm on/off means open out in the opposite direction to the path between the first chambers and second chamber.

8. Dishwashing machine as claimed in Claim 1, characterized by the fact that the nozzles are supported on arms which are made to rotate under the action of the water expelled from them.

9. Dishwashing machine as claimed in Claim 1, characterized by the fact that that the drainage outlet and the water intake on the bottom of the tub are protected by filter means against the entry of foreign bodies.

Drawing