EP1541740A1

EP1541740A1 - Detergent dispenser for washers and dishwashers

Info

Publication number: EP1541740A1
Application number: EP03028049A
Authority: EP
Inventors: Michele c/o Whirlpool Europe s.r.l. Felice; Pierluigi c/o Whirlpool Europe s.r.l. Petrali; Federico c/o Whirlpool Europe s.r.l. Betto
Original assignee: Whirlpool Europe SRL
Current assignee: Whirlpool Corp
Priority date: 2003-12-08
Filing date: 2003-12-08
Publication date: 2005-06-15
Anticipated expiration: 2023-12-08
Also published as: ES2304484T3; DE60320268D1; EP1541740B1; DE60320268T2

Abstract

A detergent dispenser (20,21,22) for an automatic laundry washing machine or dishwashing machine comprises a water inlet (14) that is controllable by a programming device (18) of the machine and a movable element (30) controllable by said programming device (18) for supplying water to different positions (22) within the detergent dispenser (20,21,22) according to the washing programme of the machine. The movable element (30) carries a water nozzle (30) and is driven by a stepper motor (30a,32) assembly.

Description

The present invention relates to a detergent dispenser for an automatic laundry washing machine or dishwashing machine, comprising a water inlet that is controllable by a programming device of the machine and a movable element controllable by said programming device for supplying water to predetermined positions within the dispenser according to the washing programme of the machine.
With the term "detergent" we mean all the products (detergents, washing or rinsing aids, softeners etc.) which are usually added during the washing and/or rinsing process of the machine.
A water distributor of the above kind is disclosed by GB-A-2188704 and by EP-A-1029965. In the first of these documents a flow control valve system comprises thermoactuators having a casing containing a thermally expandable mass and plungers acting on mechanical components in order to shift the water flow to different positions corresponding to different compartments of a detergent dispenser.
According to EP-A-1029965, a synchronous motor is used, coupled to a gearbox. Such known system presents some drawbacks. In the solution according to GB-A-2188704 the reliability of thermoactuators is not 100%, and moreover the use of mechanical links between such actuators and the moving nozzle reduces the overall reliability of the system. In the solution according to EP-A-1029965 it is necessary to use a feedback control system, and the overall dimension of the detergent dispenser is quite relevant. In both cases the overall cost of the detergent dispenser is high, mainly due to its complexity.
Another solution is disclosed by EP-A-2893596 in which a shape memory alloy wire is used. Even if such solution is very cheap and simple, it is still to be implemented and tested in mass production.
The purpose of the present invention is to provide a flow control system of the kind specified at the beginning of the description, which is very reliable, simple and of low cost.
According to the invention, the movable element of the flow control system is driven by an electromagnetic rotor/stator assembly, and preferably it is part of such assembly. The aim is to move the nozzle that drives water in a generic number of different channels or compartments to dispense pre-wash detergent, main wash detergent, fabric softener and so on. The principle underlying the present invention is an extension of a stepper motor.
Even if the rotor/stator assembly can be a stepper motor itself, it is preferably to use an assembly in which the number of poles is reduced compared to the number of poles of a stepper motor, and such number is substantially identical to the number of positions needed for the detergent distributor. Moreover the position of poles can be tailored in view of the positions that the nozzle has to reach during the washing program. This allows reducing substantially the cost of the flow control system, while it guarantees the reliability of a stepper motor system, which is nevertheless included in the scope of the present invention.
This invention will be described further, by way of example, with reference to the accompanying drawings, in which:

figure 1 is a schematic view of a clothes washing machine provided with a detergent distributor;
figure 2 is a perspective exploded view of the movable assembly of the detergent distributor according to the invention;
figure 3 is an enlarged view of a component of the assembly shown in figure 2;
figure 4 is a front view of the component shown in figure 3;
figure 5 is a perspective view of the assembly of figure 2, shown in its assembled configuration;
figure 6 is a front view of the assembly shown in figure 5;
figure 7 is a schematic view of the electrical connection of the component shown in figures 3 and 4;
figure 8 is an electrical equivalent schema of the connections shown in figure 7; and
figure 9 shows schematically the relation between angular positions of the movable element and intensity of magnetic flux.

In figure 1 a tub 10 of a washing machine is shown, in which a drum 12 is rotatably mounted. Water is supplied through a pipe 14 on which an on/off electrical valve 16 is mounted. An electromechanical or electronic control unit 18 of the machine controls such valve. Downstream the valve 16, the pipe 14 feeds water to a water distributor device 20 controlled by the control unit 18 and which is adapted to discharge a water flow to different dispensers 22 for detergents or washing/rinsing aids. The different "direction" of the water flow towards dispensers 22 is schematically shown in figure 1 by means of arrows 21. The water flow entrains the detergent and a mixture of water plus detergent is fed into the tub 10. The liquid from the tub 10 is then discharged (after washing or rinsing) by means of a pump 24.
In figure 2 an example of a water distributor according to the invention is shown, in which the water distributor device 20 is a stepper nozzle. Such stepper nozzle 20 includes two main components: a wound stator 32 that is fixed on a support S of the washing machine and a nozzle 30 which is mechanically fixed to a shaft of an electromechanical rotor 30a. The nozzle 30 can be fed through the pipe 14, which can be flexible, or through an air break (not shown). The nozzle 30 drives water inside the different dispenser 22. The wound stator 32 is mounted by snap engagement, by means of a fixing ring 32a, within the external support S that is part of the detergent dispenser itself. The rotor 30a of the nozzle 30 is rotatably mounted within the stator 32. The rotor 30a holds permanent magnet or soft iron or both. Referring to figures 3 and 4, coils 34 are wrapped on wound stator 32 and when direct current energises them, an electromagnetic field is generated. This electromagnetic field generates a torque on nozzle 30 by one of the following principles:

Variable-reluctance principle, when the rotor 30a is of soft iron;
Permanent-magnet principle, when the rotor 30a comprises a permanent magnet
Hybrid, when the rotor comprises both soft iron and a permanent magnet

By energising teeth by direct current in the correct order it is possible to control the angular position of the nozzle 30. Reversing the order of the steps in a sequence will reverse the direction of rotation.
The device could be realised with two, three or more poles per phase and with different number of phases. It is possible to drive the nozzle 30 in one of the following modes:

Wave Drive (1 phase on)
Full Step Drive (2 phases on)
Microstepping (by continuously varying the current) save

The home position of the nozzle 30 is obtained by a mechanical stop, not shown. The nozzle is connected to the rotor 30a of the device and it can be mounted inside the stator cavity when the system is assembled on the detergent dispenser or the system rotor/stator can be assembled before installing it on such dispenser. The system is unique because the shaft and the stator 32 of the stepper nozzle 26 are completely separate and the nozzle 30 is connected to the rotor of the device. Stator 32 could also integrate the system in witch it will be joined to the support S. The system is unique also because a reduced number of poles is sufficient for achieving all the positions needed for driving water inside the compartments 22 of detergent dispenser by energising coils 34 by direct current.
Figure 7 shows an example of driving strategy of the detergent dispenser according to the invention. Figure 8 shows the equivalent electrical schema.
Figure 9 explains how it is possible to control the angular position  of the nozzle 30 by controlling the intensity of magnetic flux of two adjacent phases 36. It is possible to obtain different intensity of the resultant magnetic flux H that in some position is more than 100%, as shown in the following table:
ζi =45°
1= 90°

2= 45°

H1	H2		H
0%	100%	45	100%
10%	100%	49	107%
20%	100%	52	115%
30%	100%	55	123%
40%	100%	57	131%
50%	100%	60	140%
60%	100%	62	149%
70%	100%	63	157%
80%	100%	65	166%
90%	100%	66	176%
100%	100%	68	185%
100%	90%	69	176%
100%	80%	70	166%
100%	70%	72	157%
100%	60%	73	149%
100%	50%	75	140%
100%	40%	76	131%
100%	30%	80	123%
100%	20%	83	115%
100%	10%	86	107%
100%	0%	90	100%

The hold torque changes similarly to the magnetic flux intensity, so it is possible to have similar behaviour of the torque as function of the angular position. A different strategy is to control the resultant magnetic flux to be constantly equal to 100% energising differently the two phases.

Claims

A detergent dispenser (20, 21, 22) for an automatic laundry washing machine or dishwashing machine, comprising a water inlet (14) that is controllable by a programming device (18) of the machine and a movable element (30) controllable by said programming device for supplying water to different positions (22) within the detergent dispenser according to the washing programme of the machine, characterised in that said movable element (30) is driven by an electromagnetic rotor/stator assembly (30a, 32).
A detergent dispenser according to claim 1, characterised in that the movable element (30) is part of the electromagnetic rotor/stator assembly (30a, 32).
A detergent dispenser according to claim 2, characterised in that the movable element comprises the rotor (30a) of the rotor/stator assembly (30a, 32).
A detergent dispenser according to claim 3, characterised in that the stator (32) comprises a number of poles (34, 36) corresponding substantially to the number of positions of the movable element (30).
A detergent dispenser according to any of the preceding claims, characterized in that the movable element comprises a water nozzle (30).