Field of the invention

The present invention relates to a dishwasher. Background of the invention

Dishwashers are used in domestic kitchens as well as professional kitchens and restaurants for dishing goods such as for example plates, pots, pans etc. Dishwashers comprises a washing chamber in which dishing goods are packed in one or more baskets to remain in the intended position separated from adjacent items to make it possible for water to circulate within the washing chamber and clean the items.

Water is circulated in the washing chamber by a pump arranged in the lower section of the washing chamber. The water is lead from the pump via pipes to one, or more, rotating spray arms provided with a number nozzles that are spraying water on the dishing goods to clean the dishing goods. The nozzles on the rotating spray arms are arranged to distribute water in different directions to spray water over all items in the baskets and ensure that all items are properly washed.

However, in dishwashers with a substantially rectangular shape the rotating spray arm makes it difficult to ensure a uniform washing result of all items within the basket. Critical areas are the corners of the basket since these areas are difficult to cover by the nozzles arranged on the rotating spray arm. In order to ensure the desired washing result the dishwasher operational program must be extended and additional water directed towards these areas. Unfortunately this is in contradiction to new

requirements regarding energy and water consumption for modern dishwashers and there is consequently a need for an improved dishwasher that reduces the energy and water consumption and still ensures the desired washing result. Summary of the invention

The present invention, defined in the appended claims, relates to a dishwasher that to at least some extent fulfils the need defined above. The dishwasher according to the invention comprises:

a washing chamber;

at least one basket comprising support rods and/or pins to support items to be washed in the basket;

a water circulation system arranged to feed water from a sump in the lower part of the washing chamber to a number of nozzles stationary arranged on the support rods or pins;

wherein the nozzles are arranged in groups, and the water circulation system furthermore comprises at least one flow control device, operated by a control unit, and arranged to direct water from the sump to at least one of the groups of nozzles at a time.

The dishwasher defined above fulfils the need defined above since only one or a limited number of groups of nozzles, located at different places within the basket or washing chamber, is/are used at a time in order to reduce the amount of water that must be supplied by the water circulation system. The fact that only a limited number of nozzles are spraying water at the same time reduces the size of the different components of the water circulation system as well as the energy consumption required to feed water to the nozzles. A further advantage is that a high number of nozzles could be arranged in the dishwasher since not all of them are spraying at the same time which makes it possible to arrange the nozzles at different locations in the basket such that water could be directed to all different areas within the basket where items are arranged.

Furthermore, the dishwasher according to the invention improves the final washing result compared to dishwashers comprising rotating spray arms since the rotating nozzles result in that the sprayed water will have different impact angles for all plates in the basket while the static nozzles give the same desired optimal impact angle for all plates and reach all glasses or objects in a good way, also the ones placed in the corners of the baskets. Since the nozzles can be arranged and directed to provide an efficient washing and rinsing of the items in the basket, the time and amount of water required to achieve the desired result can be reduced.

In one embodiment of the dishwasher, each group of nozzles comprises 4 to 12 nozzles. Groups comprising 4 to 12 nozzles ensure that the desired amount of water could be distributed without requiring that the capacity of the water circulation system is increased and with the energy consumption being kept at the desired level.

In one embodiment of the dishwasher, the at least one basket is either stationary or movably arranged in the washing chamber and the nozzles are arranged in the basket to distribute water over the items in the area of a group of nozzles. In one embodiment of the dishwasher, the nozzles in the basket are connected to the water circulation system when the at least one basket is inserted in the washing chamber. This embodiment is favourable since the non-permanent connection between the nozzles in the basket and the water circulation is needed when the basket is extracted from the washing chamber. Once the basket is inserted to the intended position within the washing chamber, the conduit / conduits connecting the nozzles to the water circulation system are brought in engagement with a corresponding fitting of the water circulation system in the dishwasher.

In one embodiment of the dishwasher, the support pins have an upper end and a nozzle is arranged in said upper end. Arranging nozzles in the upper end of the support pins provides a very efficient arrangement since water is sprayed straight into the gap between adjacent plates or bowls alternatively into cups or glasses arranged above the pins. Thereby a better coverage is achieved compared to current designs resulting in that the items in the dishwasher could be washed with a reduced amount of water. In one embodiment of the dishwasher, the nozzles are arranged to spray water upwards towards the items in the basket. Nozzles directed to spray water upwards towards the items in the basket are very favourable since the water is spread over the items before the water is flowing downwards by gravity towards the sump. The nozzles are preferably nozzles with a dynamic spray pattern to further increase the spread of the distribution of water over the items. This could be achieved by providing the nozzles with more than one outlet such that the water is sprayed from alternating outlets, or designed such that a fluctuating spray pattern is generated by the characteristic design of the nozzle.

In one embodiment of the dishwasher, the flow control device comprises a pump and a flow control valve operated by the control unit. This embodiment is favourable since only one pump is needed to feed the different groups of nozzles. The flow control valve is operated by the control unit and connects the pump with a pipe arranged to feed water to the selected group of nozzles.

In one embodiment of the dishwasher, two or more water circulation systems are arranged in parallel, and the flow control device of each water circulation system is operated by the control unit to feed at least one group of nozzles of each system at a time. In this embodiment, each of the water circulation systems is arranged to feed water from the sump to a number of nozzles stationary arranged in groups via a flow control device operated by the control unit, and to direct water from the sump to at least one of the groups of nozzles at a time. This embodiment is favourable in larger dishwashers to reduce the time required to finish the wash and rinse phase since water could be sprayed from more nozzles simultaneously. Furthermore, the desired functionality could be achieved with a less complex flow control device.

In one embodiment of the dishwasher, the flow control valve is arranged downstream the pump and arranged to direct the flow of water to the selected groups of nozzles.

In one embodiment of the dishwasher, the flow control valve comprises at least one inlet connected to the pump, and one outlet for each group of nozzles, said valve is operated by the control unit to distribute water to the selected at least one group of nozzles.

In one embodiment of the dishwasher, the flow control device comprises one nozzle group pump for each group of nozzles, and said nozzle group pumps is operated by the control unit and arranged to feed water to a particular group of nozzles. This embodiment is favourable since the different nozzle group pumps could be arranged at different locations within the washing chamber of the dishwasher. The nozzle group pumps could furthermore be arranged separately from the sump in the lower part of the washing chamber, which could be useful to use the space available within the dishwasher in the best way possible.

In one embodiment of the dishwasher, the nozzles belonging to the same group of nozzles are arranged in the same area of the basket. This arrangement provides a very efficient washing in the area where the nozzles are located.

In one embodiment of the dishwasher, the water circulation system, during a rinse phase of a dishwasher operational program, is arranged to only feed water once to the nozzles (40). The use of fresh, non-circulated rinse water distributed by the different groups of nozzles is very favourable since the desired rinse result could be achieved with a limited amount of water in a short period of time. This embodiment is particularly advantageous in combination with nozzles arranged in the upper end of the support pins since water could be distributed in a very efficient way between adjacent items in the basket to further reduce the amount of water required to achieve the desired rinse result. Another benefit with the fresh water rinse is that the water can be heated to a high temperature without consuming too much energy as only the water needs to be heated instead of the entire tub.

In one embodiment of the dishwasher, the flow control device is arranged to feed water to only one group of nozzles at a time. This embodiment provides a simple and reliable dishwasher since the different components are less complex and the required water circulation capacity small since only one group of nozzles is spraying water at a time.

The invention furthermore relates to a method for running a dishwasher according to anyone of the embodiments defined above. The method comprises the steps:

select a desired operational program for the dishwasher and communicate information to the control unit; and

activate the flow control device to direct water to at least one of the groups of nozzles at a time.

The method according to the invention is closely related the dishwasher defined above and fulfils the need defined since only one or a limited number of nozzles are distributing water simultaneously to reduce the amount of water that must be supplied by the water circulation system. Furthermore, a higher number of nozzles could be arranged in the basket since only a limited number are spraying at the same time.

In one embodiment of the method, the flow control device is arranged to feed water to only one group of nozzles at a time. In one embodiment of the method, during a rinse phase of the dishwasher operational program, water is only sprayed once from each group of nozzles. The use of fresh, non-circulated rinse water is favourable since the desired rinse result could be achieved with a limited amount of water in a short period of time. The different embodiment described above could of course be combined and modified in different ways without departing from the scope of the invention that will be described more in detail in the detailed description.

Brief description of the drawings

The arrangement according to the invention is schematically illustrated in the appended figures. The figures illustrate:

Figure 1 illustrates schematically a dish washer Figure 2a-d discloses selected components of a dishwasher according to a first embodiment of the invention schematically.

Figure 3 discloses selected components of a dishwasher according to a second embodiment of the invention schematically.

Figure 4 illustrates schematically a cross-sectional view of a dish washer.

Detailed description of the invention

The dishwasher 10 comprise a washing chamber 11 surrounded by a substantially rectangular cabinet 12. The washing chamber 11 comprises an opening 15 in the front side of the dishwasher in order to make the washing chamber 11 accessible during loading and unloading of items in and from the washing chamber. The opening 15 is closed by a door 13.

Within the washing chamber 11, an upper 16a and lower basket 16b for dirty items are arranged at different heights. The baskets are extractably arranged in the washing chamber and formed of thin elements like for example wires or rods in order to provide a basket structure that the water could flow through easily. The two wire baskets 16a, 16b arranged on guide rails 17 that make it possible to extract the baskets from the position within the washing chamber to an extracted position outside the washing chamber. The lower one is normally used for larger items like plates, pots etc, and the upper one for cups, glasses and smaller items. The number of baskets could however be increased further to comprise for example a third basket for small items such as cutleries arranged in the top of the washing chamber or a removable smaller basket arranged in one of the basket for cutleries, alternatively reduced to only one basket to reduce the size of the dishwasher. The basket, or baskets, could also be fixed in the washing chamber.

When the dishwasher is filled with items to be washed, the operator selects the desired operational program on a user interface 18, normally arranged along the upper front of the dishwasher or in the door. The user interface could for example be one or more buttons, or a touch screen, both displaying relevant information regarding the dishwasher and usable for selecting the desired operational program of the dishwasher. Even though most dishwashers could be operated according to a number of programs adapted for different types of items to be washed, energy consumption etc, they all comprise a wash phase and a rinse phase, each divided into several different steps.

During the wash phase, water and detergent are circulated within the washing chamber 11 in order to clean the items in the dishwasher baskets. The circulating water will contain residues from the items to be washed since the residues are mixed with the water during the washing phase. The expression water is intended to cover all possible mixtures of water, additives such as detergent, and residues. During the wash phase the water is heated to a predetermined temperature and mixed with detergent to achieve the desired washing result.

During the wash and rinse phase, water is circulated in the washing chamber by a water circulation system 20, 30. The water distributed in the washing chamber is collected in a sump 21 in the lower part of the washing chamber and led via one or more filters, not illustrated, and a flow control device 22, 32, to a number of spray nozzles 40 arranged in the basket for distribution of water over the items in the basket, or baskets, before the water returns to the sump by gravity. In order to limit the water consumption, the water is circulated several times during the wash phase. Selected components of a first embodiment of the water circulation system 20 are illustrated in figure 2a - 2d and a second embodiment 30 in figure 3. The circulation of water reduces the energy consumption since the reused water already has been heated in the previous step and the temperature only has to be maintained at the desired level. The circulated water is in the end of the wash phase drained from the washing chamber via a not illustrated water outlet in the lower part of the sump to remove the dirty water from the washing chamber.

The washing phase is followed by the rinse phase during which fresh water is sprayed from the nozzles to remove residuals and detergent. The water used during the rinse phase is only used once since in dishwashers comprising the water circulation system according to the invention with nozzles arranged in the basket between adjacent items in basket, the rinse phase could be completed in a short period of time with a limited amount of water. The fresh water rinse without circulation is particularly

advantageous in combination with the dishwasher according to the invention since the high number of nozzles, and the positions of the nozzles, ensure that all items in the basket could be sprayed in an efficient way and still ensure the desired result. The reduced amount of water consumed during the rinse phase furthermore results in that the rinse water could be heated to a high temperature before it is distributed in the washing chamber, which will improve the rinse result further as well as ensure a quick drying of the items in the basket without consuming too much energy since only the rinse water is heated instead of the entire tub.

The spray nozzles 40 are all stationary arranged at different places within the basket or baskets to distribute water over the entire area within the basket where items to be washed could be arranged. The spray nozzles 40 are arranged in groups and the flow control device 22, 32 arranged to direct water to a limited number of groups of nozzles at a time. Preferably, each group of nozzles comprises 4-12 nozzles 40 arranged together in the basket. The embodiment illustrated in figure 2a - 2d comprises four different groups of nozzles. The nozzles of the first group are illustrated with reference numeral 41, the second with 42, third 43 and fourth 44. Water is fed by the water circulation system to all nozzles within the group simultaneously for a predetermined period of time controlled by the dishwasher control unit. During the wash and rinse phase water is distributed from all groups for a predetermined time. The nozzles could be arranged at different locations but is preferably arranged in the basket close to the items to be washed, and arranged to direct water towards the expected position of the items in the basket. Support pins 50 extend from the basket bottom to support the items in the basket. It is very advantageous to arrange a nozzle in the upper free 51 end of the support pins since water could be sprayed straight into the gap between adjacent plates or bowls in the basket. This embodiment is illustrated in figure 2a - 2d and 3. In the embodiment illustrated in figure 2a - 2d, the flow control device 22 comprises a pump 23 arranged to feed water from the sump to a flow control valve 24 arranged to direct water to one of the groups of nozzles at a time. The flow control valve 24 is operated by a control unit 100 that activates the flow control valve 24 to direct the water between the different groups of nozzles.

The flow control valve 24 is arranged downstream the pump 23 and comprises one inlet 25 and the same number of outlets 26 as the number of groups of nozzles that the pump is expected to feed water to. The number of groups depends on the size and interior design of the dishwasher. The different components of the water circulation system are connected by one or more conduits 45 with dimensions suitable for the determined volumes of circulating water.

The flow control valve 24 comprises one inlet 25 leading to a valve chamber, not illustrated, and a number of outlets 26 in fluid connection with the valve chamber. The valve chamber has at least one substantially flat circular side in which the outlets 26 are arranged at the same radial distance from the centre of the flat side. The flow control valve furthermore comprises a substantially flat disk 27 with a circular hole 28 arranged at the same radial distance from the disc centre as the radial distance from the centre of the flat circular side to respective outlet. The flat disk 27 is rotatably arranged within the valve chamber adjacent to the flat circular side such that, by rotating the disk, the opening 28 in the disk 27 could be moved to arrange the valve chamber in fluid connection with the outlet connected to the desired group of nozzles. The different alternative positions of the illustrated embodiment are illustrated in figure 2a - 2d. This embodiment is favourable since only one pump is needed to feed water to the different groups of nozzles. The flow control valve, i.e. the position of the rotating disk, is operated by the control unit 100.

In an alternative configuration of the dishwasher two, or more, water circulation systems of the type described above are arranged in parallel to supply water from the sump to a number of groups of nozzles at the same time. Each parallel water circulation system will comprise the same components, i.e. a pump, flow control device and a number of nozzles arranged in groups, and has substantially the same design. Each flow control device of the different water circulation systems is operated by the control unit and arranged to feed water from the sump to at least one group of nozzles at a time. This parallel configuration is favourable if the size of the dishwasher is increased or if it is desired to reduce the operation time of the dishwasher program.

In the second embodiment, illustrated in figure 3, the flow control device 30 comprises one nozzle group pump 32 for each group of nozzles, i.e. each group of nozzles are fed by a dedicated pump 32. Each pump is started and stopped by the control unit 100 and arranged to feed water from the sump to a particular group of nozzles 40. This embodiment is favourable since the different nozzle group pumps 32 could be arranged at different locations within the dish washer. The different components of the water circulation system are connected by one or more conduits with dimensions suitable for the determined volumes of water flowing through the conduit.

The embodiments described above could be combined and modified in different ways without departing from the scope of the invention that is defined by the appended claims.