Dispenser for treatment agents in a washing machine

The present invention refers to a dispenser for treatment agents in a washing machine, in particular a dishwasher.

In dishwashers dispensers are commonly used which comprise a compartment for storing of detergent powder or tablets and in addition a container for storing of a liquid rinsing aid. The compartment is closed by a lid which is spring-loaded into open position. The lid can be selectively released by operation of a solenoid controlled by a programmer.

The dispenser also includes a dosing arrangement connected to the rinsing aid container for dosing an appropriate amount of risning aid at a proper time during the performance of a washing program. The dosing arrangement often includes a hollow piston which can accomodate a rinsing aid dose to be dispensed upon movement of said piston to a predetermined position, said movement being effected by an additional solenoid. Alternatively, the movement can be effected by a so-called wax motor which reacts more slowly giving a softer movement of the piston than is the case when a solenoid is used. A wax motor comprises three principal components, namely a block of wax, a plunger that bears on the wax and an electric heater that heats the wax. A control signal from a programmer can cause, directly or indirectly, a current flow through the heater which in turn causes the wax to melt and expand forcing the plunger to move and effect dispensing of the rinsing aid dose.

Normally, a control arrangement, such as a program controller, has to be provided with two separate outputs in order to control both the dispensing of detergent and of a rinsing aid dose. This requirement makes the control arrangement more complex and acordingly more expensive to manufacture. It is an object of the invention to simplify the design of such a control arrangement by using a single output only. The object has been achieved in a dispenser which has obtained the special

features indicated in claim 1. Preferred embodiments have been included in the associated sub-claims.

The invention will now be described more in detail in connec- tion with a preferred embodiment with reference to accompanying drawings, in which

Fig. 1 is a perspective view of a dispenser according to the invention;

Fig. 2 is a schematic sectional view of the dispenser of Fig. 1 with the piston of a rinsing aid dosing arrangement in a filling position;

Fig. 3 is a schematic sectional view of the dispenser of Fig.

1 with the piston of the dosing arrangement in a dispensing position, and Fig. 4 is a circuit diagram for a control arrangement for the dispenser.

In Fig. 1 a dispenser 10 is shown which is intended to be used in a dishwasher. The dispenser 10 is provided with a compart- ment 12 for detergent. The compartment can accomodate either detergent powder or detergent in the form a tablet. The compartment 12 is open upwards and has a lid 14 which closes the compartment at its bottom. The lid 14 can be relased to move downwards for the purpose of dispensing the detergent into a treatment chamber in the dishwasher, not shown. The lid 14 is operated by a solenoid, schematically shown and indicted by numeral 16.

With reference to Figs. 2 and 3 a container 18 is shown for storage of a rinsing aid. A floater 20 movable in a vertical tube 22 communicating with the interior of the container 18 is provided for indicating the rinsing aid level in the container.

At the bottom of the container 18 a dosing arrangement 24 is provided which comprises a so-called wax motor. The dosing arrangement 24 comprises a hollow piston 26 provided with first and second slit-shaped openings 28, 30 adapted to cooperate

with matching openings 32, 34 provided in a cylinder 36 surrounding and guiding the piston 26. The opening 32 communicates with a filling channel 38 whereas the opening 34 communicates with a dispensing channel 40 opening into the treatment chamber of the dishwasher, not shown. The piston 26 is open at its left side and the sufficient ventilation of this area is achieved by means of a ventilation pipe 27. The ventilation pipe opens at the top of the container 18 and the interior of the container is also suitably ventilated by means not shown. The wax motor is indicated by numeral 42 and comprises a space 44 containing wax. The wax bears against an end wall 46 of the piston 26. The rinsing aid container 18 can be replenished via a filling tube 48, see Fig. 1.

Turning now to Fig. 4 a control arrangement 50 is shown which can be a normal electro-mechanical programmer or, more preferably, an electronic programmer. The control arrangement 50 has one single output 52 for controlling the dispenser and the solenoid 16 and the wax motor 42 are connected in parallel to the single output 52.

The function of the dispenser shown in the drawings will now be described. Prior to the performance of a washing program in the dishwasher, not shown, the lid 14 is closed and a detergent powder dose or a powder tablet is loaded in the detergent compartment 12. Then, the washing program is started by suitable operation of the control arrangement 50 and after a predetermined time a control signal of short duration, for example of 0,2 to 1 seconds, is emitted on the output 52 causing the solenoid 16 to release the lid 14 to dispense the detergent powder dose or tablet into the treatment chamber, not shown. Because a control signal of a duration of at least 3 seconds is required for the wax motor 42 to move the piston 26 to its rinsing aid dispensing position the short control signal will only activate the solenoid 16 but not the rinsing aid dosing arrangement 24.

During a later part of the washing program a control signal will again be emitted by the control arrangement 50 on the output 52, but this time of a duration which is sufficient to operate the wax motor 42 to move the piston 16 to the left in Figs. 2 and 3 to its rinsing aid dispensing position in which openings 30 and 34 are aligned so that liquid rinsing aid contained in the hollow piston 16 will be dispensed into the dispensing channel 40 and then into the treatment chamber of the dishwasher. As described above, when the wax in the space 40 is heated it expands and causes movement of the piston 16. When the control signal has been removed from the output 52 the wax present in the space 40 in the wax motor cools down and the piston 16 is allowed to move back to the right in Figs. 2 and 3 to a position in which openings 28 and 32 are aligned to permit filling of the interior of piston 16 from the container 18 via the filling channel 38. The movement of the piston 16 to the right can be effected for example by spring means, not shown. Accordingly, the piston 16 will then contain a new rinsing aid dose ready to be dispensed during a subsequent washing progam.

Due to the fact that the solenoid 16 and the wax motor 42 can use control signals of different duration it will be possible to use one single output on the control arrangement which simplifies the design of the control arrangement and lowers the manufacturing costs thereof.

Even if the invention has been described above as applied in a dishwasher it can equally well be applied in washing machines for laundry purposes.