EP1929924A1

EP1929924A1 - Dishwasher

Info

Publication number: EP1929924A1
Application number: EP06025209A
Authority: EP
Inventors: Stellan Wrangberth; Anders Tolf
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2006-12-06
Filing date: 2006-12-06
Publication date: 2008-06-11
Also published as: WO2008067898A1

Abstract

The present invention deals with a dishwasher comprising a washing tub (2) with a filter receptacle (3) formed in a bottom of the washing tub (2), and a washing pump (5) connected to the filter receptacle (3) arranged for drawing water used in a washing phase there from and for pumping water back to the tub (2), the pump having a rotatable impeller (6) for propelling the liquid. By arranging the impeller (6) such that it is rotatable around a substantially vertical axis (R), the height that is used below the tub for the washing pump and for other components used for propelling water used in the washing phase is very low. Thereby, a high tub height can be achieved without increasing the total height of the dishwasher.

Description

Technical Field

The present disclosure relates to a dishwasher, and especially to an arrangement related to the functional components of a dishwasher.

Background

When designing dishwashers, there are space constraints imposed by standards for kitchen appliances, cabinetry, etc. For example, a dishwasher cabinet may need to fit within a space that is 817.5-877.5 mm high, 595 mm wide and 570 mm deep.
In order to maximize the amount of objects that can be washed in a tub of a dishwasher, there is a general need for space saving measures in respect of the arrangement of the functional components of the dishwasher. Especially, there are space constraints related to drawer dishwashers.
For environmental and economic reasons, there is also a general desire to provide a dishwasher that uses as little water as possible.
The functional components of a dishwasher relates to for example, a water circulation system of a dishwasher. The water circulation system comprises a filter receptacle arranged in a bottom of the tub, and a washing pump connected to the filter receptacle via an inlet channel and connected to a sprinkler system in the tub via an outlet channel. The washing pump is arranged to circulate water received from the tub via the filter receptacle such that water is propelled back into the tub via the sprinkler.
Prior art document JP 09-117401 shows a dishwasher that is arranged such as to increase storage place for tableware, i.e. to increase the volume and the height of the tub. For this reason, the washing pump is arranged such that a part of the impeller of the pump is at a higher vertical level than the bottom of the filter receptacle. If the washing pump is arranged on such a high vertical level compared to the filter receptacle, space below the tub can be saved. Although, there is a problem with arranging the washing pump on such a level because air can get into the impeller of the washing pump, which would impair the function of the washing pump, especially if air gets stuck in the impeller or if air is pumped through the pump outlet to the sprinkler. For taking care of any air in the pump, the washing machine is arranged with a passage that branches off from the pump outlet. Any air inside the washing pump will be guided through the passage back to the washing tub. Thereby, the pump and the sprinkler can work properly even if there is some air in the pump. Although this arrangement saves space, the placing of the washing pump below the pump, and especially the motor of the washing pump, takes considerable space, which may have been used to increase the tub height.

Summary

An object of the invention is to create a dishwasher in which the height of the tub is large compared to the total height of the dishwasher.
This problem is solved by arranging a dishwasher according to the preamble of claim 1 such that the impeller is rotatable around a substantially vertical axis. Since the impeller normally has a larger extension in a direction perpendicular to the axis direction than in the axis direction the total height and space taken by the functional components below the tub can be very low if the impeller is arranged to be rotatable around a substantially vertical axis.
Also, if the impeller is arranged to be rotatable around a substantially vertical axis, a pump motor driving the impeller can be placed above the impeller in accordance with claim 3. Then space is released below the tub, compared to a horizontal arrangement of the motor, space that could be used for increasing the height of the tub without increasing the total height or volume of the dishwasher.
According to claim 2, a bottom of the impeller is arranged at the same or a higher vertical level than a filter receptacle bottom.
Thereby, the height of the tub can be increased even more without increasing the total height of the dishwasher, and even more objects can be washed in the dishwasher.
By arranging the drive motor of the washing pump in a corner of the dishwasher, as stated in claim 4, the height and volume at the lower part of the tub can be increased further without increasing the total height and volume of the dishwasher.
If the impeller of a washing pump is arranged on a high vertical level compared to the filter receptacle there is a risk that there is air instead of water in a house of the pump wherein the impeller is situated, when the impeller is actuated. This may result in a malfunction of the impeller.
Therefore, according to claim 5, the dishwasher is arranged to be filled with liquid (typically water) before the impeller is actuated, to such an extent that the impeller is at least partly covered with water when the impeller is actuated. Thereby, the impeller can be placed on e.g. the vertical level indicated in claim 2 without risking malfunction.
By providing an arrangement for sensing the water level in the pump, as stated in claim 6, a proper function of the impeller can be secured.
The pump impeller does not need to be entirely immersed in water during a washing phase, but can operate in a surface region. By providing air ventilation means as provided in claim 7, it is possible to run the pump even with a very low water level, since air drawn through the pump inlet may be removed at the pump outlet.
By providing the air ventilation means as stated in claim 8, it may be ensured that, upon stopping the pump, the entire water mass in the ventilation channel is drained.
By providing an inlet channel as stated in claims 10-11, a high flow rate can be provided into the pump.
By providing a screen arranged in the filter receptacle as stated in claims 12-14, the height of the tub can be increased even more, without increasing the total height of the dishwasher. At the same time the flow of liquid to the pump can be limited or balanced.
By providing a filter receptacle as stated in claim 15, the generation of foam will be minimized in the filter receptacle.

Brief Description of the Drawings

Fig. 1 schematically illustrates a cross section of a side view of a dishwasher according to an embodiment of the invention.
Fig. 2 schematically illustrates a cross section of a top view of a dishwasher according to an embodiment of the invention.

Description of Embodiments

Figure 1 shows in cross section a side view of a drawer dishwasher according to an embodiment of the invention. A drawer 1 of a drawer dishwasher comprises a washing tub 2 having a filter receptacle 3 formed in a bottom thereof. The filter receptacle may be generally cylindrical, with a suction opening arranged at a vertical portion thereof, to draw water in a substantially horizontal direction. Inside the filter receptacle 3, there is a removable micro filter (not shown) provided. The filter receptacle 3 is connected by an inlet channel 4 to a washing pump 5. By a "pump" is meant a device capable of displacing a gas and/or a liquid from an inlet 5a to an outlet 5b.
The washing pump 5 is arranged to suck water from the filter receptacle 3 via the inlet channel 4, and to pump the water back into the tub 2 via an outlet channel 10 to a sprinkler 15 (see fig. 2) arranged in the tub 2. In this way, the washing pump 5 is arranged to circulate water in the dishwasher during the washing phase. The washing pump 5 is driven by a drive motor 8 connected to the washing pump 5, via e.g. a rotatable pump axle 7. The washing pump is operated by an impeller 6, driven by the motor 8 via the pump axle 7.
The dishwasher may also have a drainage pump (not shown) for pumping water out of the washing machine after the washing phase is completed, or at least after a period of the washing phase is completed.
The impeller 6 of the washing pump 5 is arranged such that it is rotatable around a substantially vertical axis R. An impeller normally has a wider extension in the direction perpendicular to the axis direction compared to in the axis direction. Thereby, by placing the impeller 6 such that it is rotatable around a substantially vertical axis R, the height of the tub can be increased without increasing the total height of the dishwasher drawer, compared to e.g. an arrangement such as that described in JP 09-117401 wherein the impeller is rotatable around a horizontal axis.
Also, according to an embodiment of the invention, when the impeller 6 is arranged such that it is rotatable around a substantially vertical axis, the pump motor 8 may be arranged vertically, in a direction upwards from the pump, outside the tub. Due to this measure, the height of the tub can be increased further without increasing the total height of the dishwasher, compared to the arrangement in JP 09-117401 , wherein the pump motor is arranged horizontally, below the tub, for driving a horizontally arranged impeller. Due to these measures, the whole washing pump 5 of the invention can be placed at the same vertical level or at a higher vertical level than the bottom 3a of the filter receptacle 3. Thereby, a lowest possible build height for the functional components of the dishwasher, in respect of the influence from the washing pump, can be achieved. According to a realization of the invention, a bottom of the pump is arranged 6 mm above the bottom of the filter receptacle.
If the impeller is arranged such that it is rotatable around a horizontal axis, any air inside the impeller could rather easy be evacuated from the impeller through the pump outlet. This is because when the impeller is rotated around the horizontal axis, the outlet will at a certain occasion in each revolution be on a substantially higher vertical level compared to the inlet, and the air will gravitationally be driven out of the impeller. Although, as mentioned above, the height of the tub in relation to the total height of the dishwasher will not be as advantageous with such an arrangement compared to an arrangement with an impeller rotatable around a vertical axis. If the impeller is arranged rotatable around a vertical axis, the inlet and the outlet will be on substantially the same level during a revolution and, since for solving the problem, the height of the impeller has to be low, there is more problematic to get air out of the impeller. Therefore, the pump inlet 5a could be arranged at the underside of the impeller. Also, to lower the risk of malfunction of the impeller due to air stuck in the impeller, the dishwasher may be arranged to be filled with water to such an extent that the impeller is at least partly covered with water when the impeller 6 is actuated by the pump motor 8. For achieving the best performance of the impeller, the dishwasher is preferably filled with more water after the impeller has been actuated, such that the impeller can be almost totally covered with water. Any possible air is then pushed out of the impeller, when the impeller starts to propel water and air, and the air is vented out e.g. via the air ventilation means 9. Thereby, it is possible that the residual water in the dishwasher, when the dishwasher is not running, could be totally below the impeller 6.
According to an embodiment of the invention, the dishwasher has an arrangement 13 for sensing the water level in the washing pump 5 to detect when a pump housing surrounding the impeller 6 is sufficiently filled with water for the filling phase to end and the motor 8 to start driving the impeller. The arrangement 13 for sensing the water level in the pump may be arranged to detect air pressure in a pipe 14, branching from any part of the air and/or liquid transporting system of the dishwasher, preferably downstream from the impeller 6. The branch pipe 14 is directed upwards and is closed in an end proximate to the branching end such that when water enters the branch pipe, the air stuck in the branch pipe is compressed. In this embodiment, the arrangement 13 for sensing the water level is preferably a pressure control device. In one embodiment, the branch pipe 14 branches off from the lower part of the air ventilation means 9. The arrangement 13 for sensing the water level may also be used during the washing phase to detect that there is enough water in the impeller 6. If the pressure would fall below a certain threshold value, the pressure control device may send a signal that will result in a stop of the motor 8.
Alternatively, the water level may be sensed by some kind of floatation device arranged somewhere in the inlet channel 4 or the discharge channel 10.
As mentioned above, the impeller may operate in the water surface, thereby drawing in both water and air. In that case, to provide optimal function of the pump 5, a ventilation device 9, 9a, 9b is connected to the pump outlet 5b. Hence, any air drawn in through the pump will be vented through the ventilation device, while water may be output through the water outlet channel 10 to a sprinkler (not shown) that distributes water onto washed objects placed in the tub 2.
When air is drawn through the pump, this is ventilated through the ventilation device 9, 9a, 9b, and when only water is drawn through the pump, a water jet may be provided through the ventilation device. The water jet may be used to provide additional wetting of the washed objects in the tub 2, in addition to the sprinkler. For this reason, the ventilation device 9 may be connected to the tub 2, through e.g. an opening in the tub.
Figure 2 shows schematically a top view of cross-section of a drawer dishwasher according to an embodiment of the invention. This figure shows the pump motor 8 placed in a corner of the drawer 1, arranged above the impeller 6. Thereby, if the pump motor is manufactured to be sufficiently slim in a horizontal direction, it will not influence the length of a spray arm 15 arranged in the bottom of the tub 2, which spray arm is arranged to, when in use, rotate around its central axis 16 and spray water received from the washing pump 5 through nozzles arranged on the spray arm 15.
According to another embodiment of the invention, the pump 5 is connected via the inlet channel 4 to an opening in a substantially vertical surface of the filter receptacle 3, to draw the liquid in a substantially horizontal direction there from, to thereby limiting or balancing the flow of liquid to the pump 5. For this reason, the filter receptacle 3 is provided with a screen 11 providing a slot 12 between the lower edge of the screen 11 and the bottom 3a of the filter receptacle 3. The slot limits or balances the flow of liquid to the pump 5 with the purpose of achieving an even suction power in all positions of the filter receptacle 3. By making the part of the slot 12 closest to the opening to the inlet channel 4 small, and increasing the slot in a direction away from the opening to the inlet channel, the same liquid velocity can be achieved in the whole filter receptacle. By balancing the flow of liquid in this way, the filter receptacle 3 could be produced with a lower height compared to prior art filter receptacles, without risking that air will be sucked into the filter and further to the pump, which would result in a pressure fall in the water circulation system. The flow of liquid is preferably balanced by designing the screen such that the slot between the screen and the bottom of the filter receptacle in each position of the screen is proportional to the distance from the opening of the inlet channel.
Thanks to this design of the slot 12, a reversing water movement is created when the pump 5 is switched off, which clears the micro filter from any dirt that is stuck in the filter.
According to a further embodiment of the invention, the filter receptacle 3 is substantially cylindrical and has a horizontal diameter that is more than 1.5 times its vertical height, preferably more than 2 times, most preferably more than 3 times. By this measure, low flow speed is provided through the filter receptacle 3, which minimizes generation of foam, which would otherwise occur when running at a low water level. If the height of the filter receptacle is decreased, the diameter is increased such that the area of the receptacle for water to pass through is kept substantially constant.
According to another embodiment of the invention, an upstream portion of the inlet channel 4 has a wider cross section than a downstream portion of the inlet channel 4. Thereby, a high flow rate can be provided into the pump 5. This is advantageously realized by providing the upstream portion of the inlet channel 4 with a substantially circular cross section, and the downstream portion of the inlet channel 4 with a substantially semi-circular cross section. Although, other realizations can be thought of, such as providing the inlet channel with a continuously narrowing cross-section in the direction of the pump 5.
According to a still further embodiment of the invention, the air ventilation means 9, 9a, 9b comprises an upstream ventilation channel section 9a connected, at a first end, to the pump outlet 5b and a downstream ventilation channel section 9b, connected to a second end of the upstream ventilation channel section 9a. The cross section of the upstream ventilation channel section 9a is larger than the cross-section of the downstream ventilation channel section 9b. By making the upstream ventilation channel sufficiently wide and long, the air ventilation means can be created such that stationary water will not be present in the narrow downstream ventilation channel 9b. Thereby, it is ensured that the entire water mass residing in the air ventilation means 9 is drained after water has retracted from the air ventilation means, as a result of e.g. stopping of the pump. Thereby, there is no risk of a plug of water getting stuck in the air ventilation means 9.
The arrangement described in the application could be used in any dishwasher, such as drawer dishwashers. Since the pump 5 is placed inside a drawer of the drawer dishwasher, the total height of the dishwasher drawer can be on a low level, compared to the height of the tub 2. For this reason, the dishwasher will also be easy to handle when a drawer is drawn out of the dishwasher. Also, since the number of components placed outside the drawer is minimized, the risk of components getting stuck and thereby risking damage when a drawer is drawn out is low. The invention may be used in drawer dishwashers with one drawer, or drawer dishwashers with two or more drawers, wherein one drawer is arranged on top of the other drawer(s). In such a multi-drawer dishwasher, the arrangement of the invention may be used in one drawer, in more than one drawer, or in all drawers of the dishwasher.
Although the invention as described in the detailed description is mainly described for a drawer dishwasher it might as well be used for saving space in a conventional dishwasher.
In the drawings and specification, there have been disclosed preferred embodiments and examples of the invention and, although specific terms are employed, they are used in a generic' and descriptive sense only and not for the purpose of limitation, the scope of the invention being set forth in the following claims.

Claims

A dishwasher comprising:
a washing tub (2) with a filter receptacle (3) formed in a bottom of the washing tub (2), and

a washing pump (5) connected to the filter receptacle (3) arranged for drawing liquid there from and for pumping liquid back to the tub (2), the pump (5) being connected to the filter receptacle (3) via an inlet channel (4), the pump having a rotatable impeller (6) for propelling the liquid, characterized in that the impeller (6) is rotatable around a substantially vertical axis (R).
The dishwasher as claimed in claim 1, wherein a bottom of the impeller (6) is arranged at the same or a higher vertical level than a filter receptacle bottom (3a).
The dishwasher as claimed in claim 1 or 2, further comprising a pump drive motor (8) for driving the impeller (6), and wherein the pump drive motor (8) is arranged above the impeller (6) such that its longitudinal axis has a substantially vertical direction.
The dishwasher as claimed in claim 3, wherein the pump drive motor (8) is arranged in a corner of the dishwasher.
The dishwasher as claimed in any of claims 1-4, wherein the dishwasher is arranged to be filled with water, before the impeller (6) is actuated, to such an extent that the impeller (6) is at least partly covered with water when the impeller (6) is actuated.
The dishwasher as claimed in any of claims 1-5, comprising an arrangement (13) for sensing the water level in the pump (5).
The dishwasher as claimed in any one of the preceding claims, wherein air ventilation means (9, 9a, 9b) is provided at a pump outlet (5b) for discharging air drawn in through the inlet channel (4).
The dishwasher as claimed in claim 7, wherein said air ventilation means (9, 9a, 9b) comprises an upstream ventilation channel section (9a) connected, at a first end to the pump outlet (5b) and a downstream ventilation channel section (9b), connected to a second end of the upstream ventilation channel section (9a), wherein the cross-section of the upstream ventilation channel section (9a) is larger than the cross-section of the downstream ventilation channel section (9b).
The dishwasher as claimed in claim 6 and 7, wherein the arrangement (13) for sensing the water level in the pump (5) is arranged to detect air pressure in a pipe (14), branching from the air ventilation means (9).
The dishwasher as claimed in any of the preceding claims, wherein an upstream portion of the inlet channel (4) has a wider cross section than a downstream portion of the inlet channel (4).
The dishwasher as claimed in claim 10, wherein an upstream portion of the inlet channel (4) presents a substantially circular cross section, and a downstream portion of the inlet channel (4) presents a substantially semi-circular cross section.
The dishwasher as claimed in any one of the preceding claims, wherein the washing pump (5) is connected via the inlet channel (4) to an opening in a substantially vertical surface of the filter receptacle (3), to draw the liquid in a substantially horizontal direction there from.
The dishwasher as claimed in claim 12, wherein a screen (11) is provided in the filter receptacle (3), the screen having a slot (12) for limiting or balancing the flow of liquid to the pump (5), and wherein the slot (12) is provided between a lower edge of the screen (11) and the filter receptacle (3) bottom.
The dishwasher as claimed in claim 13, wherein the screen (11) is designed such that the slot (12) is narrow close the opening in the substantially vertical surface and broader in positions further away from the opening in the substantially vertical surface.
The dishwasher as claimed in any of the preceding claims, wherein the filter receptacle (3) is substantially cylindrical and has a horizontal diameter that is more than 1.5 times its vertical height, preferably more than 2 times, most preferably more than 3 times.
The dishwasher as claimed in any of the preceding claims, wherein the dishwasher is a drawer dishwasher, and the tub (2) and the washing pump (5) are arranged in a drawer (1) of the drawer dishwasher.