Improved electromagnetic actuator for washing and similar machines

Abstract: A first and a second moving member (7, 8) are provided with respective permanent magnets (9, 10) having a mutually opposing polarity so as to exert a mutually repulsing force that keeps said moving members (7, 8) in their resting position. The magnets (9, 10) are adapted to get linked with the magnetic field generated by a solenoid (4) when the latter is supplied with a unidirectional voltage having a first and a second polarity. The corresponding magnetic field generated in this manner exerts a pushing force (A; B) capable of overcoming said mutually repulsing force and selectively switching said first or said second moving member (7, 8) into a working position.

Description: The present invention refers to an electromagnetic actuator adapted for use in washing or similar machines to control the operation of operational component parts thereof, such as valves or mechanical devices as they may be used in such machines, eg. leverages for the actuation of command or control mechanisms. Washing machines are generally known to make use of various operational organs, in particular electrically operated valves, which are normally idling and must in fact be temporarily operated only in correspondence of certain operation phases of the machine, for example in view of enabling water to be delivered into a detergent dispenser and/or a washing vessel or tank. Each such operational organ of the above cited kind is again generally known to be operable through a respective electromagnetic actuator that mainly comprises a solenoid which is energizable by the application of an alternating current to switch over a moving member from a resting position to a working position. In the general case of an electrically operated valve, such a displacement of the moving member into the working position thereof causes the same valve to open. Such a reduction in component count has been proposed in IT-A-1 203 572, in which one or more evaporators can be selectively inserted in a refrigerating circuit by means of a bistable flow-deflecting electromagnetic valve. The latter comprises a solenoid actuator adapted to be energized with electric pulses of different polarity to switch over said valve from a first operational position to a second operational position, or vice-versa, in which the same valve then remains when no current is applied to the solenoid. This solution enables a single electromagnetic actuator to be used, which however is only capable of switching the valve to and from said two above cited operating positions. The valve can in fact work to only deviate a flow of an inflowing fluid, while it is not capable of shutting off such a flow. Conclusively, such an operating capability can actually find a use in refrigerating circuits and similar applications, but is fully inadequate in the case of washing or similar machines, in which it is basically necessary for the actuator to be capable of normally determining also a resting position of the valve. It therefore is a main purpose of the present invention to provide an improved electromagnetic actuator for washing and similar machines, which enables the number of the main component parts to be drastically reduced. A further purpose of the present invention is to provide an electromagnetic actuator of the above cited kind, the operation of which is particularly suited to the use thereof in washing machines. According to the present invention, these aims are reached in an electromagnetic actuator for washing and similar machines embodying the features as recited in the appended claims. Characteristics and advantages of the invention will anyway be more readily understood from the description that is given below by way of non-limiting example with reference to the accompanying drawings, in which: Figures 1 to 3 are views of a preferred embodiment of the present invention respective operating conditions thereof. With reference to the above Figures, the actuator can be noticed to mainly comprise a solenoid 4 having two terminals 5, 6 to which a unidirectional voltage can be applied so as to generate a corresponding electromagnetic (magnetostatic) field extending in a substantially axial direction. The actuator further comprises two actuating members 7, 8 that are freely movable with respect to the solenoid 4, with respect to which they are preferably coaxial. In a preferred manner, said actuating members are capable of freely sliding axially inside a support body 21 made of non-magnetic material, eg. plastics, around which the solenoid 4 is wound. The actuating members 7, 8 are arranged side by side with each other axially, at a certain distance from each other, wherein each one of them comprises a respective permanent magnet 9, 10. Said magnets 9 and 10 are arranged with mutually opposing polarities, eg. as illustrated in Figure 1, so as to be capable of mutually repulsing each other axially. Moreover, said magnets 9 and 10are adapted to link with the magnetic flux generated by the solenoid 4 when the latter is energized with the above cited unidirectional voltage. As this will be described in greater detail further on, said magnetic flux develops in a sense that is dependent on the direction of winding of the solenoid 4 and the polarity of the unidirectional voltage applied to the terminals 5, 6. In the preferred example of embodiment illustrated in the Figures, the moving members 7, 8 are adapted to actuate respective valves which are normally closed (when at rest) and have respective inlets 13, 14 and respective outlets 15, 16. In a per se known manner, said inlets 13, 14 of the valves 11, 12 are adapted to communicate with the respective outlets 15, 16 when the valves are in their operating position. To this end, the valves 11, 12 (which are only represented schematically in the Figures owing to reasons of greater simplicity) comprise appropriate hydraulic communication passages 17, 18 which are normally closed by respective sealing gaskets 19, 20. These are connected to said moving members 7, 8, respectively, which are in turn hydraulically isolated by means of respective flexible sealing diaphragms 22, 23. The valves 11, 12 can be used in a clothes washing machine, a dishwashing machine or the like to control respective water flows that must be delivered, for example, into a washing tub or vessel through respective compartments of a washing and/or rinsing aid dispenser, in a substantially per se known manner. During machine operation, when no voltage is applied to the terminals 5, 6 the moving members 7, 8 are kept in their normal resting position shown in Figure 1, in which the valves 11 and 12 are closed, owing to the magnetic force of mutual repulsion exerted by the magnets 9, 10. When a unidirectional voltage having a first polarity is then applied to the terminals 5, 6, as illustrated for example in Figure 2, the corresponding magnetic field generated by the solenoid 4 exerts on the magnet 10 a pushing force (represented by the arrow A in Figure 2) that keeps the moving member 8 in the position in which the associated valve 12 is closed. At the same time, the above cited pushing force A is capable of overcoming the force of mutual repulsion existing between the magnets 9, 10 and, as a result, axially displaces the magnet 9, jointly with the associated moving member 7, into a position (shown in Figure 2) in which the sealing gasket 19 opens the valve 11 by disengaging the hydraulic communication passage 17. When a unidirectional voltage having a second polarity, ie. a polarity that is opposite to the first one, is then applied to the terminals 5, 6, as illustrated in Figure 3, the corresponding magnetic field generated by the solenoid 4 exerts on the magnet 9 a pushing force (represented by the arrow B in Figure 3) that keeps the moving member 7 in the position in which the associated valve 11 is closed. At the same time, the above cited pushing force is capable of overcoming the force of mutual repulsion existing between the magnets 9, 10 and, as a result, axially displaces the magnet 10, jointly with the associated moving member 8, into a position (shown in Figure 3) in which the sealing gasket 20 opens the valve 12 by disengaging the hydraulic communication passage 18. As soon as the control voltage applied to the terminals 5, 6 is removed therefrom, ie. come to cease, the electromagnetic actuator will of course switch back automatically into its resting position shown in Figure 1, owing to the action of mutual repulsion of the two magnets 9, 10. Anyone skilled in the art will readily appreciate that the application of the above-cited unidirectional voltages with opposite polarity can be controlled and performed in any of a number of suitable manners existing to such a purpose, eg. by means of a (per se known and not shown) bridge-type electric circuit or by each time applying a suitable control voltage between one of the terminals 5, 6 and a further terminal (not shown either, for reasons of greater simplicity) provided on the solenoid 4 in an intermediate position thereof. In any case, the electromagnetic actuator according to the present invention has a simple and reliable structure and, above all, requires just a single solenoid to selectively operate two distinct valves 11, 12, or any other similar operational organs, into respective resting and operating positions. Conclusively, in the considered application in a washing machine the number of electromagnetic actuators needed to operate a plurality of operational organs or parts is substantially cut by half. It will be appreciated that the above described electromagnetic actuator may be subject to a number of variations and modifications without departing from the scope of the present invention. For instance, instead of operating two water-flow valves 11, 12, at least one of said moving members 7, 8 may be used to operate a linkage or leverage system used to actuate a per se known control or actuation mechanism.

Claims: Electromagnetic actuator for washing machines, comprising a solenoid capable of being supplied selectively with a unidirectional voltage having a first and a second polarity so as to generate a magnetic field having a corresponding sense, characterized in that it further comprises a first and a second moving member (7, 8) that are adapted to operate associated operational valves (11, 12), said moving members being provided with respective permanent magnets (9, 10) having mutually opposing polarities so as to exert a mutually repulsing magnetic force that normally keeps said moving members (7, 8) in a resting position thereof, said magnets (9, 10) being adapted to link with said magnetic field generated by the solenoid (4), which exerts a pushing force (A; B) adapted to overcome said repulsing force and selectively switching said first or said second moving member (7, 8) into a respective operating position thereof when said unidirectional voltage has said first or said second polarity, respectively.. Electromagnetic actuator according to claim 1, characterized in that said moving members (7, 8) are arranged side by side with each other axially, at a certain distance from each other. Electromagnetic actuator according to claim 1, characterized in that at least one of said operational valves (11, 12) comprises a water flow control valve with at least an inlet (13; 14) and an outlet (15; 16) that are capable of being connected to each other through a passage (17; 18) adapted to be selectively closed or opened by a sealing gasket (19; 20) connected to a corresponding moving member (7, 8), when the latter switches from said resting position and said operating position thereof and vice-versa.

Inventors: FRUCCO GIUSEPPE, PERESSI VALENTINO, FRUCCO, GIUSEPPE, PERESSI, VALENTINO
Applicants: ELECTROLUX ZANUSSI ELETTRODOME, ELECTROLUX ZANUSSI S.P.A.
Application year: 2000
Main classification: H01F7
IPC codes: H01F7