GB2168388A

GB2168388A - Program control apparatus for a washing machine

Info

Publication number: GB2168388A
Application number: GB08530801A
Authority: GB
Inventors: Walter Heissmeier; Irmgard Rothmund
Original assignee: Licentia Patent Verwaltungs GmbH
Current assignee: Licentia Patent Verwaltungs GmbH
Priority date: 1984-12-15
Filing date: 1985-12-13
Publication date: 1986-06-18
Also published as: FR2574823B1; GB2168388B; IT8523164A0; DE3445877C2; GB8530801D0; DE3445877A1; FR2574823A1; IT1215322B

Abstract

A program control apparatus for a washing machine has a washing drum (2) which receives the laundry to be washed and spin-dried. The drum 2 is in a container (1) out of which used detergent solution can be drawn off by means of a pump (4) disposed in a waste pipe (3). The pumping out of the container (1) is carried out after termination of the washing action and before the beginning of the spin-drying action with the washing drum at first stationary. The detergent solution is pumped out except for a column of water present in the waste pipe (3) below the container (1). Then the washing drum (2) is operated with a spin-drying action at a relatively low speed so that the level of the detergent solution oscillates between the water column and an upper level (h2) of detergent solution which is, however, outside the region of immersion of the washing drum (2) in the container (1) for detergent solution. The spin-drying action at relatively low speed is carried out until the water column has reached a value substantially below level (h2). Only then is the washing drum (2) brought to a higher spin-drying speed. <IMAGE>

Description

SPECIFICATION Program control apparatus for a washing machine This invention relates to program control equipment for a washing machine of the kind having a rotary drum for receiving laundry to be washed and located within an outer container for detergent solution, a motor for driving said drum to provide, respectively, a rotary washing action, and a centrifuging action for spinning the laundry dry, and a pump, located within a waste pipe from said outer container, for discharging liquid from the container.

Washing machines of this kind correspond to the well known prior art. In such washing machines, the spin-drying action and the pumping of the detergent solution out of the container for detergent solution generally begin simultaneously after termination of the washing operation. At this moment, the container for detergent solution contains practically its full or maximum supply of water.

After the beginning of the spin-drying, the spindrying operation reaches a value of about 500 r.p.m. or a higher value with a rapid increase in the speed of rotation of the washing drum. The discharge pump of the washing machine cannot, however, immediately pump out completely the amount of water present and accumulating. The water present or remaining in the container for the detergent solution is entrained by the washing drum and forms a ring of water which eludes the action of the discharge pump. An unwanted foaming may also occur in the container for the detergent solution and in particularly unfavourable circumstances there is even the risk of discharge of foam from the machine.

It is the object of the invention to design control equipment of the type initially referred to above so that a large proportion of the amount of water accumulating has already been eliminated from the washing drum or the laundry before the washing drum runs up to the maximum spin-drying speed.

In this case, it is intended, above all, to ensure a foam-free operation of the machine after termination of the washing operation.

The invention accordingly provides a programme control apparatus as initially referred to wherein said apparatus is arranged to actuate said motor and said pump in such a manner that the pumping of the detergent solution out of the container for detergent solution is carried out after termination of the washing action and before the beginning of the centrifuging action, with the washing drum at first stationary, that the detergent solution is pumped out except for a column of water remaining in the waste pipe below the container for detergent solution, that the washing drum is then operated with a centrifuging action at a low speed so that the level of the detergent solution oscillates between the column of water and an upper level of detergent solution ocurring outside the region of immersion of the washing drum in the container for detergent solution, that the centrifuging action at low speed is carried out until the column of water has reached a value substantially below the above-mentioned level of the detergent solution and that only then is the washing drum brought to a higher centrifuging speed in comparison with the initial centrifuging speed.

Preferred optional features of the invention are apparent from the sub-claims appended hereto.

What is now important is that the centrifuging sped of the washing drum and hence the spindrying of the laundry only begins after the detergent solution present in the container for detergent solution has been pumped out and that at first a start is made with a relatively low speed of rotation of the washing drum which is then gradually increased. From this there results the advantage that only as much water comes out of the laundry at a time as can be pumped out by the discharge pump without a backwash. As a result, the effect is achieved that the washing drum and hence the laundry no longer comes into contact with the detergent solution after termination of the washing operation and foaming on starting the spin-drying operation is out of the question.

The invention is illustrated by way of example in the accompanying drawings, in which: Figure 1 is a diagrammatic elevation of a washing machine, and Figure 2 is a similar view of another arrangement.

Referring to Figure 1 a container for detergent solution of a washing machine not otherwise illustrated is designated by 1, in which a washing drum 2 serving to receive the laundry is accommodated for rotation. The washing drum 2 is provided over its whole generated surface with perforations for the passage of water or detergent solution and can be driven by a motor selectively with a washing action or with a spin-drying action. This washing drum can thus also carry out the spin-drying of the laundry which generally terminates a washing program. A waste pipe 3 with a discharge pump 4 starts from the bottom of the container 1 for detergent solution. During the whole washing and rinsing operation, the perforated washing drum containing the laundry is partially immersed in the liquid (detergent solution, rinsing water) present in the container 1.The height of the liquid in the container 1 is designated by h1. The drive for the washing drum and the motor for the discharge pump 4 are controlled by an electrical program control device, not illustrated, which is accommodated in the housing of the washing machine and can be appropriately selected.

The mode of operation of the washing machine described is as follows: In order that the washing drum 2 with the laundry can no longer come into contact with the detergent solution (h1 ) in the container 1 at the beginning of the spin-drying operation, the discharge pump 4 is first set in operation after termination of the washing operation and with the washing drum 1 at first stationary or moving and the detergent solution is lowered to below the container 1, by pumping out, to such an extent that a column of water, the height of which is designated by h3, still remains in the waste pipe 3, on the upstream side of the discharge pump 4. Thus the discharge pump 4 is prevented from delivering air.When the lower of the detergent solution to a water level h3 is finished, switching over to spindrying action is effected and the washing drum 2 is at first controlled for a time at a relatively low spindrying speed of about 150 r.p.m. to 200 r.p.m. in such a manner that the level of the detergent solution oscillates between the water column (h3) in the waste pipe 3 and an upper level of detergent solution or water which is present outside the region of immersion of the washing drum 2 in the container 1 and which is designated by h2. The spin-drying action at relatively low speed may appropriately be carried out in steadily rising speed steps. For example: 300 r.p.m., 400 r.p.m. and 550 r.p.m. may be provided as speed steps.

The spin-drying action at relatively low speeds is carried out until the water column has reached a value far below the level of the detergent solution h2 in the container 1. Only after that is the washing drum brought to a higher spin-drying speed of about 800 r.p.m. and above, in comparison with the initial spin-drying speed.

A preferred arrangement is shown in Figure 2, wherein the same reference numerals designate the same parts as in Figure 1. In this case, the discharge pump 4 is controlled through a level sensor 5. The level sensor 5 is connected by its measuring pipe 5' to the waste pipe 3 between the discharge pump 4 and the container 1 so that it is influenced by the column of water in the waste pipe 3 of the container. The level sensor 5 is so designed that the water level in the waste pipe 3 and the container 1 oscillates between a "maximum" and a "minimum". The "minimum" water level in the waste pipe 3 is somewhat above the measuring connection point for the level sensor 5. Here the operating sequence is that after termination of the washing operation and stopping of the washing drum 2 before the beginning of the spin-drying operation at low speed, the discharge pump 4 is switched on.This runs until the level sensor 5 reports a water level (water column) in the waste pipe 3 which prevents or rules out the drawing in of air through the discharge pump. The discharge pump 4 is then switched off and the spin-drying operation described begins with a relatively low speed at first or the spin-drying operation is initiated with a somewhat higher water level (water column) and the discharge pump continues to be operated. The level sensor 5, which is designed as a so-called two-position control and which has the effect that the level of the detergent solution or water oscillates continuously in the range Ah (hysteresis of the sensor), may, with appropriate design, also be replaced by a continuous control with appropriate feedback. Instead of the pulse-width control (on/off) described for the washing drum, a pole-changeable drive may also be used which is continuously live during the draining-off phase and which is then changed over to another number of poles at a preset time. This method is likewise possible with electronic drives in that, instead of the pole-changing, the set value is appropriately al tered by the programmable controller.

The discharge pump 4, which may also be a transverse-flow pump for example, is in any case controlled so that the different amounts of water accumulating during the spin-drying operation are always reliably pumped out.

Claims

1. A program control apparatus for a washing machine of the kind having a rotary drum for re ceiving laundry to be washed and located within an outer container for detergent solution, a motor for driving said drum to provide, respectively, a ro tary washing action, and a centrifuging action for spinning the laundry dry, and a pump located within a waste pipe from said outer container, for discharging liquid from the container said appara tus being arranged to actuate said motor and said pump in such a manner that the pumping of the detergent solution out of the container for deter gent solution is carried out after termination of the washing action and before the beginning of the centrifuging action, with the washing drum at first stationary, that the detergent solution is pumped out except for a column of water remaining in the waste pipe below the container for detergent solu tion, that the washing drum is then operated with a centrifuging action at a low speed so that the level of the detergent solution oscillates between the column of water and an upper level of deter gent solution occurring outside the region of im mersion of the washing drum in the container for detergent solution, that the centrifuging action at low speed is carried out until the column of water has reached a value substantially below that above-mentioned level of the detergent solution and that only then is the washing drum brought to a higher centrifuging speed in comparison with the initial centrifuging speed.

2. A programe control apparatus as claimed in Claim 1, wherein the arrangement is such that the said at least one initial centrifuging speed com prises a series of steadily rising speeds.

3. A program control apparatus as claimed in Claim 1 or 2, wherein said pump is controlled by means of a level sensor.

4. A program control apparatus as claimed in Claim 3, wherein the level sensor is arranged to be influenced by the column of water in the waste pipe of the container for detergent solution.

5. A program control apparatus as claimed in .$aim 3, wherein the level sensor is so designated that the water level oscillates between a minimum and a maximum.

6. A program control apparatus as claimed in any one of Claims 1-5 wherein the motor has op tionally selectable different numbers of working poles, and the arrangement is such that the num ber of working poles is changed after termination of the centrifuging action at low speed.

7. A program control apparatus as claimed in any one of Claims 1-6 wherein the arrangement is such that the pump is controlled so that the differ ent amounts of water occurring during the centri fuging operation are pumped out.

8. A washing machine incorporating a program control apparatus as claimed in anyone of Claims 1-7.

9. A washing machine substantially as described herein with reference to Figure 1 or Figure 2 of the drawings.