GB2099462A

GB2099462A - Washing machine

Info

Publication number: GB2099462A
Application number: GB8214339A
Authority: GB
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1981-05-21
Filing date: 1982-05-17
Publication date: 1982-12-08
Also published as: IT8121865A0; ES512349A0; DE3218883A1; ES8306202A1; FR2506354B1; IT1138385B; GB2099462B; FR2506354A1

Abstract

In order to avoid detergent wastage, especially in wash cycles which take place at a relatively low water temperature, e.g. between 30 DEG and 60 DEG C, the delivery side of the washing machine pump 8 is connected to a conduit or tube 11, the height of which is at least approximately equal to the maximum height of the drum 7 contained in the tub 3. Furthermore, after the operation or operations involved in feeding the detergent or simultaneously therewith, the discharge pump 8 is controlled by pulse means which determine a series of short operating periods of the pump alternated by halt periods, such that the water with the undissolved detergent is made to rise in the conduit or tube during such operating periods, and then descend then the pump is stopped, thus obtaining a to-and-fro movement which favours the dissolving of the detergent. The water column is able to descend by virtue of the fact that the pump commonly used in washing machines is of the centrifugal type, which does not hinder such backward flow. <IMAGE>

Description

SPECIFICATION Washing machine The invention relates to a washing machine comprising a tub, a laundry drum rotatably mounted in the tub and driven by an electric motor, a discharge pump hydraulically connected to the tub, a detergent tray having an inlet which can be connected to the water mains, which tray is hydraulically connected to the tub, and a programmer for controlling the washing machine operating cycles. For controlling the various working cycles, these machines comprise a programmer, known as a timer, which can be either electromechanical (in which a set of cams acts on contactors connected into electrical power circuits) or electronic (in which an electronic process circuit of the integrated or separate component type controls the electrical power circuits by means of electronic contactors).Each wash cycle of such washing machines includes feeding the tub with a given quantity of detergent, which is normally in the form of a coarse powder.

This feed is effected by the wash water, which "sweeps" the drawer or tray in which the detergent is placed, before reaching the tub. It has been found that a certain quantity of detergent does not dissolve during the prewash and wash stages in spite of the heat and the reciprocating movements transmitted to the drum, the reason being that part of the detergent accumulates in the tub discharge section which is very little influenced by the motion transmitted to the water by the drum.

The loss of detergent is obviously greater the lower the water temperature, and is certainly not neglible at the present time, when working temperatures tend to be reduced in order to save energy.

The object of the present invention is to obtain complete use of the detergent in washing machines of the type described.

Accordingly, the invention provides a washing machine of the type defined in the opening paragraph, characterized in that the delivery side of the discharge pump is connected to a conduit or tube which rises to a height which is substantially not less than the highest point of the drum, and in that control means are provided in the programmer for determining a series of short operating periods of the discharge pump alternating with halt periods during the course of the wash stage and possibly of the prewash stage.

The water (together with the detergent) rises in the conduit or tube during the operating periods and descends during the halt periods, thus favouring dissolving of the detergent.

The control means, which can be in the form of cams or electronic circuits, provide for energising the motor for relatively short times, preferably between 1/10 and 2 seconds. However, the minimum period is chosen such that the pump effectively starts to operate, i.e. manages to pump, and the maximum period is chosen such that water discharge is prevented.

The invention will be more apparent from the detailed description of two preferred embodiments given hereinafter by way of nonlimiting example with reference to the accompanying drawing, in which: Figure 1 is a diagrammatic vertical section through the washing machine with certain parts omitted for clarity, and because they do not relate to the invention; and Figure 2 is a similar partial view of a modification to the washing machine shown in Figure 1.

In the Figures, the reference numeral 1 indicates overall a washing machine for domestic use, comprising a housing 2, a tub 3, for example elastically suspended in the housing, and a tray 4 into which the user loads the detergent both for the wash and the prewash, and which is provided with a nozzle 5, from which the water required for the working cycles emerges, to then pass through the elastic conduit 6 and into the tub together with the detergent. The nozzle may for example be moved automatically from one side to the other of the tray in order to act at different times on the detergent load intended for the prewash and on that intended for the wash.

The machine also comprises a drum 7 rotatably supported by the tub 3 and driven by an electric motor (not shown) fixed to this latter. A centrifugal discharge pump 8 is also present, its suction side being connected by a flexible hose 9 to the bottom discharge port 10 of the tub 3. The delivery side of the pump is connected to a conduit or tube 1 1 which at its highest point is, at least, approximately at the height of the highest point on the contour of the drum 7. The end of said conduit projects outside the housing, and a flexible discharge hose 12 is mounted over its projecting end.

The operating cycles of the washing machine are conventionally set (by means of buttons and/or knobs) on a programmer (timer) 1 2A or 1 2B. The programmer can be of the electromechanical type, such as that shown by 1 2A, in which a set of cams is controlled by a synchronous electric motor and control electrical contacts connected into a power circuit, or it can be of the electronic type 1 2B comprising integrated and/or discrete components, with a memory containing the various programmes which can be selected, and acting on electronic contactors or the like connected into the power circuits.

In the case of the electromechanical programmer, a cam 14 or cam assembly with or without speed reduction gears is provided to act on an electrical contact 13 which controls the electricity supply to the electric motor associated with the discharge pump, such that during one or more determined stages of the wash cycle, it is cyclically operated for short periods alternated with halt intervals of greater duration. In this embodiment, the contact 13 is located in parallel with the contact 15, which is usually provided for controlling the discharge stage or stages of the pump 8, and designed to be operated by another cam 16. The electronic programmer 1 2B can comprise a controlled silicon diode acting as an electronic contactor controlled by the programmer in such a manner as to likewise supply the motor of the pump 8.The duration of the cyclic operating periods is chosen such that the water column in the tube 11 is brought very close to the level X at which the water would discharge into the flexible discharge hose 12. It is apparent that this time is related not only to the type of pump but also to the level Y of the water contained in the tub and to the capacity of the conduit 11 above this level, this capacity being able to be increased by providing an expansion chamber 17 as shown by broken lines in Figure 1. This particular movement, which concerns all the water contained in the tub, in the conduits 9, 11 and in the pump 8, means that the detergent undergoes a similar movement which favours its dissolving.

Assuming that a wash programme has been set which comprises both a prewash and a wash stage, then the operation takes place as follows: The detergent quantities necessary for the prewash and wash are placed in two different compartments Z and P of the tray 4 separated by a baffle 20, and the mahine is operated by pushing the start button. The prewash water enters the compartment Z of the tray through the nozzle, and entrains the detergent present therein as it discharges into the tub 3. The drum moves in both directions with alternate halts and movements.

When the necessary water quantity has been fed, the water is heated (by a heating element, not shown) disposed in the tub. Simultaneously, or slightly afterwards, the pump 8 is operated cyclically for short periods separated by halts, for example by means of the cam 14 and contact 1 3.

The consequent already-described movement of the entire water, including that contained in the discharge section 10 and tube 9 where the amount of undissolved detergent is high, causes practically complete dissolving of the detergent.

When the prewash stage has terminated, the dirty water is discharged by the pump as the cam 16 closes the contact 15, on which the contact 13 opens and the cam 13 becomes deactivated.

Discharge takes place with simultaneous centrifuging of the laundry. The pump then stops, and centrifuging ceases.

The nozzle 5 then moves into the section P, the wash water enters the tub together with the detergent, and the drum makes alternate movements in both directions, separated by halts.

When the necessary water quantity has been added, the water heats up and the cam 14 again acts, to cause the pump 8 to operate in the described manner, thus leading to proper dissolving of the new detergent quantity. The pump operation continues for a certain time determined experimentally, at the end of which the detergent is practically completely dissolved.

Washing continues for the necessary time.

Discharge of the dirty water combined with centrifuging then follows, followed by one or more rinse stages with clean water plus centrifuging.

Finally, high speed centrifuging takes place for partial drying of the laundry.

The embodiment of Figure 2 differs from that of the preceding Figure in that the conduit 1 1A connected to the delivery side of the pump opens into a chamber 1 7A of a certain capacity (the purpose of which is to increase the mass of water which the pump can move during the detergent dissolving stage). The chamber 1 7A communicates with the discharge hose 1 2A by way of an overflow 21. During the dissolving of the detergent, the water in the chamber 1 7A does not reach a level such as to discharge through the overflow 21. In a modification shown by dashed lines in Figure 2, the conduit 1 A can extend into the chamber 1 7A for a certain distance. The base of this chamber can be connected to the tub 3 by means of a flexible hose 30 of small cross-section.

The discharge hose 1 2A can be connected to the top or upper part of the chamber 1 7A, as indicated by Z. In this manner, a unidirectional circulation through the return hose 30 is associated with the to-and-fro action of the water column in the conduit 11 A.

Claims

1. A washing machine comprising a tub, a laundry drum rotatably mounted in the tub and driven by an electric motor, a discharge pump hydraulically connected to the tub, a detergent tray having an inlet which can be connected to the water mains, which tray is hydraulically connected to the tub, and a programmer for controlling the washing machine operating cycles, characterized in that the delivery side of the discharge pump is connected to a conduit or tube which rises to a height which is substantially not less than the highest point of the drum, and in that control means are provided in the programmer for determining a series of short operating periods of the discharge pump alternating with half periods during the course of the wash stage and possibly of the prewash stage.

2. A washing machine as claimed in Claim 1, characterized in that the duration of each short pump operating period is such that the water does not escape from the conduit or tube.

3. A washing machine as claimed in Claim 1, characterized in that a chamber is provided in the conduit or tube in order to increase the capacity thereof.

4. A washing machine as claimed in any previous Claim, characterized is that the programmer is electromechanical.

5. A washing machine as claimed in any of Claims 1 to 3, characterized in that the programmer is electronic.

6. A washing machine as claimed in Claim 1, characterized in that the tube or conduit extends into a chamber which is connected at its base to the tub and at its top to the discharge hose.

7. A washing machine substantially as herein described with reference to Figure 1, or to Figure 1 as modified by Figure 2, of the accompanying drawing.