GB2161699A

GB2161699A - Filter arrangement in a dishwashing machine

Info

Publication number: GB2161699A
Application number: GB08513046A
Authority: GB
Inventors: Wolfgang Steck; Josef Ilg; Rudiger Eiermann
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-07-19
Filing date: 1985-05-23
Publication date: 1986-01-22
Also published as: FR2567745A1; GB2161699B; IT1185228B; SE8503504D0; IT8521523A0; FR2567745B1; DE3426661C1; SE456636B; GB8513046D0; IT8522473V0; SE8503504L

Abstract

A dishwashing machine comprising an outlet trough (2) provided with connecting stub pipes (3, 4) for a circulating pump and a discharge pump contains a filter assembly comprising fine sieves (5) (6) and a coarse sieve (8) arranged within sieve (6). The coarse sieve (8) has slots (10) in its upper part (9) for passage of food remnants and openings in its lower part (11) having a size smaller than a predetermined grain size of a granular cleaning agent. This permits any retained cleaning agent to be dissolved in liquid recirculated. <IMAGE>

Description

SPECIFICATION Filtration in a dishwashing machine The present invention relates to a dishwashing machine.

Filtration equipment of a dishwashing machine is disclosed in DE-PS 27 03434. In order to prevent, in the program sections between switching-off of a circulating pump and switching-on of a discharge pump, food particles from floating up between a coarse sieve and a fine sieve cylinder and reaching a funnel-shaped fine sieve, the upper coarse sieve part has no sieve openings and forms an encircling, downwardly open annular chamber to trap such particles. Provided in the lower coarse sieve part are large sieve openings which allow coarse soft food remnants to pass to the discharge pump.

For the mechanical cleaning of crockery, cleaning agents are used, which usually consist of granulates or powders. In known dishwashing machines, in which the lid of a cleaning agent feed device is opened in program-controlled manner by an electromagnet or a bimetallic element, the cleaning agent is rinsed out of a supply container of the feed device by rinsing water and passes into an outlet trough provided in the base of the rinsing container.

A proportion of the agent deposits in the outlet stub pipe to the discharge, does not dissolve at least during the actual cleaning phase, because the water in the outflow pipe is not circulated, and is pumped away unused into the outlet by the discharge pump.

Apart from the resulting environmental pollution, a high cleaning agent consumption is caused by the required increased metering of agent. Since the agent residues in the outlet trough bottom can be partially dissolved only during the clear rinsing operation, the rinsing result is impaired.

For the return of the cleaning agent deposited at the container base of a drum washing machine, it is known to provide a further duct from the discharge pump to the base of the container and to rinse the agent back into the container (DE-GM 78 13 880).

This requires additional connecting ducts between the container and discharge pump, special sealing locations and, in some cases, switch-over elements and thereby higher production costs.

Problems can also arise in dishwashing machines in which the cleanng agent chamber of the metering equipment is additionally protected by a protective grating (DE-OS 25 08 730) and cleaners are used which are not optimised in respect of their rate of solution or have coagulated through extended storage of partially used packages. A cleaning agent not completely dissolved during the rinsing operation leads to a worse cleaning result and impairs the effect of the acid clear rinsing agent.

There is thus a need for filtration measures which protect the pumps against coarse materials but allow dirt particles to pass, which do not lead to clogging or damage of the pumps, and which avoid the disadvantages of unused cleaning agent depositing on an outlet trough bottom.

According to the present invention there is provided a dishwashing machine comprising a rinsing container, an outlet trough arranged at the base of the container and provided with respective connection means for a circulating pump and a discharge pump, and filter means arranged in the trough and comprising a fine sieve having a funnelshaped upper portion and a cylindrical lower portion which defines an outlet duct to the connection means for the discharge pump, a potlike coarse sieve being arranged in the outlet duct in flow paths to at least one of the connection means and provided in its upper region with coarse sieve openings for passage therethrough of soft wastematerial and in its lower region with fine sieve openings having a clear mesh size smaller than a predetermined grain size of a granular cleaning agent.

The coarse sieve fulfils the task of separating coarse materials from rinsing liquid to be circulated and restraining them from entry into the pumps so that the pump impellers are neither blocked nor destroyed. On the other hand, soft food remnants, for example larger milk skins, vegetable remnants and the like can pass the coarse sieve through its larger openings in the upper part and pumped away by the discharge pump. The sieve openings in the lower part have such a clear mesh size that the coarse sieve forms a collecting container for solid coarse dirt particles, which can be emptied by, for example, withdrawal of the coarse sieve from the machine. The lower coarse sieve part also forms a collecting container, particularly for coarsely granulated cleaning agent.The cleaning agent granulate is held back by the coarse sieve and cannot pass directly to the discharge pump connection means. In the coarse sieve, the cleaning agent is exposed to the liquid current produced by the circulating pump so that it is dissolved.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a schematic sectional view of the lower part of a rinsing container of a dishwashing machine embodying the invention; and Fig. 2 is a view, to an enlarged scale, of a coarse sieve of the machine of Fig. 1.

Referring now to the drawings, there is shown a dishwashing machine provided at its bottom trough 1 with an outlet trough 2, which has a connecting stub pipe 3 for a circulating pump and a connecting stub pipe 4, at the outlet trough base, for a discharge pump. Disposed above the outlet trough is a fine sieve 6, which in funnel shape passes over into a fine ('fine' or 'finest' mesh) sieve cylinder 6, which is arranged in the trough and bounds an outlet duct 7 to the stub pipe 4. A coarse sieve 8 is arranged in the duct 7.

In the illustrated embodiment, the upper part 9 of the coarse sieve 8 has several horizontally extending slots 10, elongate holes or the like, which are arranged one above the other and the slot width of which is selected so that soft food remnants, for example milk skins, salad remnants, spinach or the like, which are swept into the coarse sieve and float up therein, can pass through the slots 10 and be pumped away by the discharge pump. Heavy, hard remnants, such as bones, glass fragments or the like deposit in the lower part 11 of the sieve 8 and are separated out from the liquid current to the pumps.

The lower coarse sieve part 11 can, as shown in Fig. 2, have a closed shell 12 and a sieve bottom 13 or a sieve shell and a closed bottom or a sieve bottom and a sieve shell. The clear mesh size of the sieve openings 14 of the lower part is so designed that the coarse undissolved cleaning agent grains, when they are rinsed into the filter equipment after the addition of agent, are held back in the lower sieve part until their dissolution. Since the coarse sieve is exposed to the current generated by the circulating pump, the dissolution of the cleaning agent is accelerated. The clear mesh size of the sieve openings 14 of the lower part 11 is preferably about 1 millimetre.

The coarse sieve 8 can be a withdrawable insert in the fine sieve 5 or can be combined with the fine sieve to form one part, especially in the case of plastics material sieves. In the case of clogged sieve openings 14 of the lower part 11, heavy and coarse components can continue to deposit in the coarse sieve 8, whilst the cleaning agent rinsed into the sieve 8 flows away through the slots 10 in the upper part 9 together with rinsing liquid.

Claims

1. A dishwashing machine comprising a rinsing container, an outlet trough arranged atthe base of the container and provided with respective connection means for a circulating pump and a discharge pump, and filter means arranged in the trough and comprising a fine sieve having a funnelshaped upper portion and a cylindrical lower portion which defines an outlet duct to the connection means for the discharge pump, a potlike coarse sieve being arranged in the outlet duct in flow paths to at least one of the connection means and provided in its upper region with coarse sieve openings for passage therethrough of soft waste material and in its lower region with fine sieve openings having a clear mesh size smaller than a predetermined grain size of a granular cleaning agent.

2. A dishwashing machine as claimed in claim 1, wherein the coarse sieve openings comprise horizontally extending elongate passages disposed one above the other in a circumferential wall portion of the coarse sieve.

3. A dishwashing machine as claimed in either claim 1 or claim 2, wherein the fine sieve openings of the coarse sieve have a clear mesh size of substantially one millimetre.

4. A dishwashing machine as claimed in any one of the preceding claims, wherein the fine sieve openings are present in at least one of a base and a circumferential wall portion of the coarse sieve.

5. A dishwashing machine substantially as hereinbefore described with reference to the accompanying drawings.