EP2173229B1

EP2173229B1 - Dish washer provided with a drying system

Info

Publication number: EP2173229B1
Application number: EP08779428.5A
Authority: EP
Inventors: Thomas Persson; Kent Karlsson
Original assignee: Asko Cylinda AB
Current assignee: Asko Cylinda AB
Priority date: 2007-07-09
Filing date: 2008-07-08
Publication date: 2014-05-07
Anticipated expiration: 2028-07-08
Also published as: SE531447C2; SE0701646L; DK2173229T3; WO2009008828A1; EP2173229A4; EP2173229A1

Description

TECHNICAL FIELD

The present invention relates to a dishwasher provided with a drying system according to the preamble to claim 1.

BACKGROUND ART

Through US 4,188,732 , for example, it is previously known to use a fan to produce a forced air flow through the washing chamber in the dishwasher. In the known system, an inlet fan is arranged with its inner inlet opening in the bottom wall of the washing chamber. Even though the opening is situated at a certain height above the bottom, there is a risk of wash water running down beneath the machine in specific conditions, such as in heavy foaming. Furthermore, there is no active evacuation, i.e. fan, on the outlet side to evacuate the air in the washing chamber.
EP-A-1721559 discloses a dishwasher according to the preamble of claim 1.

DISCLOSURE OF INVENTION

The object of the present invention is to provide a dishwasher having a drying system which gives a more effective drying and hence a shorter program time.
The above object is achieved by means of the dishwasher according to the invention, the characteristics of which emerge from the following claim 1.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be described below on the basis of an example with reference to the appended drawings, in which:

fig. 1 is a schematically shown perspective view of a dishwasher provided with a drying system according to the invention,
fig. 2 is a schematically shown side view of a dishwasher provided with the drying system according to the invention,
fig. 3 is a schematically shown front view of a dishwasher provided with the drying system according to the invention,
fig. 4 is a perspective view of an inlet unit belonging to the drying system according to the invention,
fig. 5 and 6 show different partial views of the inlet unit.

MODE(S) FOR CARRYING OUT THE INVENTION

In fig. 1, 2 and 3 is shown a dishwasher provided with a drying system according to the invention. The dishwasher is constructed with a container 1 which can be opened to the front by lowering of a door 2, which normally, i.e. in the closed state, covers a container opening 3 intended for loading of the wash items 5. The door is usually pivotably connected to the container by means of hinges in the vicinity of the lower portion of the door. The container 1 encloses a washing chamber 4 in which the wash items 5 are placed in pull-out baskets 6, 7 for cleaning according to a chosen program for, essentially, washing, rinsing and drying. In the example the baskets are two in number, a lower basket 6 and an upper basket 7, but can vary in number and function, for instance there can be just one or, alternatively, three or more on two or more levels, supplemented by one or more special baskets, such as cutlery baskets. In principle, the washing can be realized in a conventional manner by spraying with hot, detergent-containing water and rinsing with hot water. To this end, a sprinkling system is present, having rotary sprinkler arms, usually one at the top beneath the upper basket and one at the bottom beneath the lower basket, possibly supplemented by fixed sprinkler arms for selected zones.
The container 1 forms the main part of a dishwasher housing standing on two pairs of legs 8, 9, a front pair and a rear pair. The container is box-shaped and has two mutually opposing parallel side walls 10, 11, a rear wall 12, a top part 13 and a bottom part 14. As a result of the legs, a space 15 is formed beneath the bottom part, in which various machine elements, such as strainer, pumps, hoses, etc., are housed. A detachable base plate 16 screens off the machine space to the front.
The drying system according to the invention is made up of an air inlet unit 17, for the forced, controlled air injection of heated external air into the washing chamber 4, and an interacting air evacuation unit 18, for the evacuation of air from the washing chamber to the environment. The air inlet unit 17 extends from the machine space 15 on the underside 19 of the bottom part 14 toward a lower edge 20, rounds this and extends a little way up along the outside 21 of one of the side walls.
The structure of the inlet unit can best be seen from fig. 4, 5 and 6 and, in the example, is a rigid, coherent unit made of, for example, hard plastic and forms with its enclosing walls essentially an inlet duct 22 having an outer inlet end 23, forming an inlet opening for air from the environment, and an inner inlet end 24, forming an opening for the injection of air into the washing chamber 4. The inlet unit incorporates an inlet fan 25, which is integrated with the inlet duct 22, i.e. the interior of the fan housing 26, in the example, is in direct open communication with the inlet duct. It might be said that the fan sits in the inlet duct or the outer end thereof. In the example, the fan housing 26 is fixedly mounted on the underside 19 of the bottom part 14. the fan, in the example, being of the radial fan type, having a blade wheel 27 or an impeller, driven by an electric motor 28, and upwardly and downwardly directed inlet openings 29, 30 for the admission of air from the environment, i.e. the machine space 15 which is filled with air from the environment outside the dishwasher. The fan 25 is mounted at some distance from the underside 19 of the bottom part 14, so that even the topmost of the outer inlet openings can suck in air. In the example, the interior of the fan housing 26 forms a duct portion 31 of the inlet duct 22 which has a substantially flat or horizontal extent, i.e. with a substantially horizontal flow direction for the inlet flow.
The inlet unit 17 also incorporates a heating element 32, which is fitted in the inlet duct 22 and, in the example, is constructed as a flow-through electrical resistance battery for controlled heating of the through-flowing inlet air. The control system can, on the one hand, be a thermostat control and, on the other hand, a chosen connection by manual activation, or coupled to a chosen program. Advantageously, the heating element 32 is electrically driven of the PTC element type (PTC - Positive Temperature Control) having a resistance which increases with increasing temperature and thus gives a built-in automatic power regulation in dependence on, inter alia, the chosen flow velocity, which can therefore be varied. Advantageously, an overheating protection in the form of a cutout at a certain maximum temperature is also included. In the example, the heating element 32 is situated such that it connects to the fan housing 26 and is situated close to the end of the flat duct portion 31, which, after the heating element, passes into a curved duct portion 33 extending around the outside of the rounded edge portion 20 of the container. The curved duct portion passes into an upright or substantially vertical duct portion 34, which extends a little way upward on the outside of one of the side walls 10 and which therefore creates a substantially vertical flow direction of the inlet flow.
The upright duct portion 34 of the inlet unit 17 passes at the top into a duct portion 35, which is curved by an angle of about 180 degrees and is situated on the outside 21 of the side wall 10, see fig. 1, 2 and 4, and which turns downward in the flow direction of the inlet air, see flow arrow 49. The closing end of the curved duct portion 35 has an arc-shaped bottom edge 50, which extends along the lower edge 51 of a circular cutout 36 in the side wall 10 of the container. Through the cutout 36, the inlet duct 22 is led through the side wall into the washing chamber 4 of the container 1, a liquid seal against the escape of dishwasher liquid being arranged around the cutout. The inlet duct 22 has over the greater part of its extent a very flat construction of relatively large width, viewed horizontally along the plane of the side wall 10, and low duct height for accommodation within the modular dimension of the machine. At the lead-through through the cutout 36, the inlet duct 22 has incrementally increased height and extends into the container 1 with its inner inlet end 24. The cutout 36 has an area which markedly exceeds the cross-sectional area of the inlet duct 22, with a transverse dimension which substantially corresponds to the width of the inlet duct before the lead-through and, in the case of a circular cutout, a corresponding height. As a result of the enlarged duct height in the lead-through, a substantially continuous flow direction downward can be created, despite the incremental lateral displacement of the inlet duct into the washing chamber 4. The inlet end 24 is configured as a nozzle 37 or mouthpiece, which directs the inlet flow of the air in a chosen direction in the container, see flow arrows 52, 53 in fig. 2. The nozzle 37, as can be seen from fig. 4, is configured in the example as an incrementally widened portion of the inlet duct with its opening 24 directed downward and in a slot shape, slightly conically widened in the downward direction. Through turning of the flow direction in the curved duct portion, a condensation barrier for condensed air is formed, so that condensation can run downward and out through drainage holes 54, situated in the bottom 55 of the inlet unit 17, after the heating element 32, thereby affording protection against moisture from within the interior of the machine. The inlet unit 17 is complete with electric connectors 56, 57 for, on the one hand, an electrical voltage feed to the PTC element and, on the other hand, an electrical voltage feed to the inlet fan 25. The electric connector 56 for the PTC element 32 sits, in the example, directly on the element and extends through holes 58 in a widened portion 59 in the duct wall, which forms a holder for the heating element. In the example, the electrical connector 57 for the inlet fan 25 is fitted to the fan housing 26.
The air evacuation unit 18 is shown schematically in fig. 1, 2 and 3 and essentially consists of an evacuation duct 38 and an evacuation fan 39 in the duct for driving the air from the interior of the container 1, i.e. the washing chamber, to the environment. At its inner end, the evacuation duct has an inner opening 40, which is situated relatively high up in the washing chamber and at a relatively large distance from the inner end 24 of the inlet duct 22. At its outer end 41 the evacuation duct has an inlet opening, which is lowly situated. The evacuation unit 18 is advantageously arranged in a known manner in the door 2 of the dishwasher, with the inner opening 40 placed high up in the door on the inside of the inner wall 42 of the door. The evacuation duct 38 extends downward in the interspace 43 between the inner wall and the outer wall 44 of the door and emerges in the bottom of the door with an outlet opening 45 at its outer end 41, an opening in the lower edge 46 of the door ensuring the discharge of the air. The evacuation fan 39 is expediently situated in the top of the duct 38 and can also be designed to suck air from the interspace in the door in order to mix drier air in with the evacuation air from the dishwasher and thus reduce the moisture content in the outlet air. The evacuation fan, too, is controlled, for example program-controlled or sensor-controlled.
By means of the above-described drying system, a high-grade effective drying is obtained by the forced air exchange which is obtained with the active injection of preheated air through the inlet unit and an air evacuation in balance with the injection. Through balance between injection and evacuation, excess pressure in the washing container, and hence leakage into the electronics or out into the kitchen fixtures, is avoided. It is advantageous that the inlet fan 25, as well as the evacuation fan 39, has relatively high capacity, for example 20-25 m/min, and that the heating element 32 has relatively high power, for example 400 W. As a result, a strong air exchange can be obtained, at the same time as the inlet air can be given a large heat content, for example at the level of 95 degrees C in the inlet duct, so that the drying is not dependent on accumulated heat in the wash items due to rinsing in water at high temperature. The drying system copes without difficulty with wash items of low thermal capacity, such as plastics objects.
As is shown with flow arrows 52, 53 in fig. 1 and 2, the air inlet 24 is advantageously directed downward, i.e. not upward toward the inner evacuation opening, so the air flow makes detours within the washing chamber, more specifically is directed down toward or beneath the lower basket containing wash items, sweeps round this and flows onward and upward through the upper basket and sweeps round the wash items thereof. The water on the surface of the wash items is hereupon vaporized by a constant supply of warm air. The air current with the higher moisture content is then evacuated through the evacuation unit due to the local underpressure which is created in the evacuation duct of the evacuation fan 39 on the suction side thereof, i.e. in front of this latter.
The drying phase in the washing program is normally a concluding part which is automatically started once the rinsing is completed. The drying phase can either be pure air exchange with air of ambient temperature, with the inlet fan and evacuation fan 25, 39 in operation for a predetermined time, or with the heating element switched on for all or part of the time for the injection of warm or hot air. The control can in both cases be realized in interaction with sensors, such as thermostats and/or moisture sensors. The fans can be controlled either with an on/off control or with a speed control.
Even though the main function is the drying of wash items, the system can advantageously be used to heat up plates, serving dishes, etc., which can be rapidly heated by the circulation of heated air. The control is in this case most easily realized with a special heating program.
The invention is not limited to the above-described examples shown in the drawings, but can be varied within the scope of the following claims. For example, the inlet unit can be directed rearward and can emerge in the rear wall. In order to increase the air quantity, a plurality of inlet units and outlet units can be present, for example an inlet unit which emerges in each of the side walls or in combination with a unit in the rear wall. It is here important to control the air currents so that they interact in the washing chamber. It is also conceivable for the inlet fan to be placed behind the dishwasher, but what is consistent is that the inlet fan is expediently positioned and that the inner opening of the inlet is expediently positioned for the air flow, irrespective of the placement of the fan. The drying system can be combined with conventional drying using radiant heat and convection heat from heating elements in the bottom of the washing chamber.

Claims

A dishwasher provided with a drying system for controlled drying of wash items by forced air exchange in the washing chamber (4) of the machine, which has two opposing side walls (10, 11), a rear wall (12), a top part (13), a bottom part (14), an opening (3) for loading of the wash items, and a door (2) for closure of the opening, wherein the drying system incorporates an evacuation duct (38) for the evacuation of air from the washing chamber to the environment by means of an evacuation fan (39), and an inlet duct (22) for the admission of an air flow from the environment to the washing chamber, wherein the inlet duct (22) extends along the outside of any one of the side walls (10, 11) or the rear wall (12) from an outer inlet end (23) and through a cutout (36) in the respective wall and emerges with an inner inlet end (24) on the inside of the respective wall in the washing chamber, and wherein adjacent to the inlet duct there are disposed an inlet fan (25) and a heating element (32) for preheating of the inlet air flow, whereby the washing chamber can be flowed through by air through both the forced admission of air and the forced evacuation of the air, wherein the inlet fan (25) is situated in a space (15) beneath the bottom part (14) and the inlet duct (22) extends beneath the bottom part from the inlet fan and toward the outside of any one of the side walls (10, 11) or the rear wall (12), wherein the inlet duct (22) extends a little way upward on the outside of any one of the side walls (10, 11) or the rear wall (12) and turns downward with a curved duct portion (35) before the lead-through through the cutout (36), characterized in that the inlet duct (22), the inlet fan (25) and the heating element (32) form a substantially L-shaped inlet unit (17) of low duct height in relation to its duct width, so that the inlet unit, including in its portion on the outside of the side wall (10), is located within the external dimensions of the machine, and in that the cutout (36) has an area which markedly exceeds the cross-sectional area of the inlet duct, whereby the lead-through laterally displaces the inlet duct (22) incrementally, but essentially creates a continuous flow direction downward.
The dishwasher as claimed in claim 1, characterized in that the cutout (36) in the wall (10) is circular.
The dishwasher as claimed in claim 2, characterized in that the inner inlet end (24) is situated in a nozzle (37) which is situated within the cutout (36) and which directs the air current from the inlet end downward along the inside of the wall (10-12) in which the nozzle is situated, away from the location for the inner opening (40) of the evacuation duct (18).
The dishwasher as claimed in claim 1, characterized in that the inlet fan (25) is controllable, and in that the heating element (32) is designed for controlled heating of through-flowing inlet air.
The dishwasher as claimed in claim 4, characterized in that the heating element (32) is an open unit, which is fixedly fitted in the inlet duct (22) and is designed to be flowed through by the inlet flow from the inlet fan (25).
The dishwasher as claimed in claim 5, characterized in that the heating element (32) is electrical of the PTC element type, with power control in dependence on the temperature, and hence the velocity, of the air flow.
The dishwasher as claimed in claim 6, characterized in that drainage holes (54) for the discharge of condensation water are disposed in the bottom (55) of the inlet unit (17) after the heating element (32).