DE29923594U1 - dishwasher - Google Patents

Description

·

Meiko072 G ' 1S.09.-2000 Bm/la

dishwasher

The invention relates to a dishwasher according to the
Preamble of claim 1.

Such a dishwasher has a single ! washing chamber in which all washing processes take place, or ;

several rinsing chambers connected in series, each of which has an associated rinsing water chamber. Furthermore, i

&igr;

a circulation pump for the rinsing water is provided, which has at least one pressure line and spray nozzles in the rinsing chamber·

&igr;&igr;

Rinse water is sprayed onto the items to be washed. The used rinse water falls back down into the rinse water tank, where it is pumped through a suction line into a
Rinse circuit fed again to the spray nozzles of the rinsing chamber
Furthermore, a collection facility such as
: a sieve to retain dirt in the rinse water tank
; intended. '

When providing several rinsing chambers, as is the case in commercial
^! Dishwashers are common, often a

Pre-wash chamber, a main wash chamber and a post-wash chamber
The items to be washed are transported from one washing chamber to the next via belts or the like.

When filling the rinsing water into the rinsing chamber and the

When the dishwasher is started, certain
Problems related to pressure conditions during the start-up phase
Firstly, there is often no

Pressure equilibrium within the rinsing chamber between a
30

upper rinsing area and a lower rinsing area, which can lead to abrupt one-sided impacts on the dishes and even
This can lead to the dishwasher falling over. On the other hand, room air is introduced at the same time as the dishes are being washed. This air is
the circulated hot rinse water is suddenly heated when the circulation pump is started, which leads to a short-term
explosive pressure increase within the rinsing chamber
In addition, this increased pressure is released via

in ^J

the door seals etc. and can even lead to water leaking out of the sealing areas.

A number of different measures have already been taken to prevent these problems.

machines with warm water filling, the effect of the sudden expansion of the air inside the washing chamber, for example, prevents the washing water tank from being filled when the circulation pump is running. The circulation pump cannot immediately

build up full operating pressure and the heating of the air inside the flushing chamber takes place more slowly.

In commercial dishwashers, the wash chamber j is pre-rinsed with hot water from the rinse nozzles before the wash water enters the spray nozzles. When the circulation pump is started ^, this prevents the air inside the wash chamber from suddenly expanding, as it is already pre-heated. The disadvantage of this is that valuable, expensive rinse water is used up.

Another way to prevent the sudden expansion of the air inside the rinsing chamber when starting operation is to use special speed controls and controllers for the circulation pump motor, whereby the speed of the pump motor is only gradually increased to the nominal speed when starting.

As a result, the operating pressure of the circulation pump is built up slowly and gradually, and the heating and the associated expansion of the air inside the rinsing chamber takes place accordingly slowly. The disadvantages are the high cost of speed control and the higher risk of electromagnetic interference in the entire electrical system or control electronics.

The invention is based on the problem of designing a ^dishwasher according to the preamble of claim 1 in such a way that a sudden expansion of the air inside the washing chamber at the start of operation and a pressure shock of the washing water on the items to be washed are largely avoided.

AlV ₁ V ATZ":" G\m?

· · ■

The object is achieved according to the invention by the features of the characterizing part of claim 1. Further embodiments of the invention are protected in the subclaims.

In a dishwasher of the type according to the invention, air is added to the hot rinsing water supplied to the circulating pump or pumps at the start of rinsing, so that the circulating pumps do not reach their full capacity. The effective surface of the hot rinsing water sprayed in the washing chamber, which comes into contact with the cold interior air in

This significantly reduces the amount of air that comes into contact with the pump and causes it to expand explosively due to thermal expansion! The throttling effect of the added air is based on the centrifugal force that the rotating pump impeller exerts on the water-air mixture in the pump housing and the intake line. As a result of this centrifugal force, the heavier water is thrown outwards and the added air is pressed inwards into the intake line. There, this air blocks the free cross-section of the intake line so that the normal intake line can no longer be reached.

A control device with a control valve can be used, the control can be done via time control; dosing of the air supply is also possible.

The opening time for air supply in the initial phase is preferably between 0.5 and 10 seconds, preferably between 1.5 and 3 seconds. The size of the air supply hole is between 1 and 10% of the pump suction opening.

A washing chamber usually has an upper spray device and a lower spray device, between which the items to be washed are arranged. This means that the pressure distribution between these two spray devices must be as equal as possible, which is positively influenced by the air supply device according to the invention in that the pressures on the items to be washed are not as extreme at first.

-:;··.:jB'i*:4 4*a*i:4 31.* . :

4
An embodiment of the invention is shown in the drawing.

The only figure 1 shows a schematic arrangement of a dishwasher with a single washing chamber. 5

For this purpose, 10 generally designates a dishwasher. This essentially consists of a washing chamber 12 with an upper spray device 32 and a lower spray device 34, between which the items to be washed 38 are arranged on a holder. Nozzles 36 spray the washing water from above and from below onto the items to be washed 38. The hot, pressurized washing water is fed from a peripheral outlet of a circulation pump 20, which is driven by a flanged motor 22, via an upper pressure line 28 and a lower pressure line 30 to the upper spray device 32 and the lower spray device 34. The hot washing water 18 is fed axially from a washing water tank 14 to the centrifugal circulation pump 20 via a suction line 24. A heating device 16 for the washing water and a dirt collecting device 40 within the washing water tank are indicated schematically.

In the subject matter of the invention, an air supply device 26 is provided on the side of the suction line 24 for the flushing water, which can be switched on and off or the supply quantity can be controlled by a solenoid valve or another valve.

In the embodiment shown, a switching device 31 with a delay circuit is provided parallel to the switch 29 for switching on the dishwasher via the control line 23 to the drive motor 22, which closes the air supply device 26, which is initially open when switched on, again after an adjustable period of time, for example after 1.5 to 3 seconds, via a control line 33 valve 27.

· · · · · • • ·· · · ·· * m ■ · * · ·
· · · t ··· · · · ·· · *

The control valve 27 can also be coupled with a temperature ^sensor , which suppresses or prevents the opening of the controllable valve 27 during special rinsing programs, for example cold water program, since in this case the sudden expansion of the air inside the rinsing chamber does not occur.

Claims (9)

1. Dishwasher, with at least one washing chamber ( 12 ), a washing water tank ( 14 ) assigned to each washing chamber, optionally a heating device ( 16 ) for the washing water ( 18 ) in the washing water tank ( 14 ), a circulation pump ( 20 ) for the washing water with motor drive ( 22 ), which sucks the heated washing water ( 18 ) from the washing water tank ( 14 ) via a suction line ( 24 ) and supplies it via at least one pressure line ( 28 , 30 ) to spray nozzles ( 36 ) of at least one spray device ( 32 , 34 ) in order to spray washing water onto items to be washed ( 38 ) which are held on a holder ( 36 ) within the washing chamber ( 12 ) in order to produce a washing circuit, and with collecting devices ( 40 ) for dirt, characterized by an air supply device ( 26 ) into the suction line ( 24 ) of the circulation pump ( 20 ) and a control device ( 27 , 29 , 31 , 33 ) such that air is supplied only in the initial phase of the rinsing process with hot water. 2. Dishwasher according to claim 1, characterized in that the control device contains a controllable valve ( 27 ). 3. Dishwasher according to claim 1 or 2, characterized by a temperature sensor ( 35 ) in the region of the air supply device ( 26 ), which opens the control valve ( 27 ) when hot rinsing water is supplied, and by a timer device (31) for closing the control valve ( 27 ) after a set time. 4. Dishwasher according to claim 1 or 2, characterized by the actuation of the control valve ( 27 ) depending on the washing program and an adjustable time. 5. Dishwasher according to one of claims 1 to 4, characterized by a metering device for the supplied air. 6. Dishwasher according to one of claims 1 to 5, characterized by a solenoid control valve in the form of a two-way valve or a three-way valve. 7. Dishwasher according to one of claims 1 to 6, characterized by an opening time of the air supply device ( 26 ) in the initial phase of the hot water rinsing process between 0.5 to 10 seconds, preferably 1.5 to 3 seconds. 8. Dishwasher according to one of claims 1 to 7, characterized by an upper ( 32 ) and a lower spray device ( 34 ), between which the items to be washed ( 38 ) are arranged. 9. Dishwasher according to one of claims 1 to 8, characterized in that the size of the air supply hole is 1 to 10 percent of the pump suction opening.