The present invention relates to a microwave oven comprising an oven chamber, a door hinged to said chamber and switches for providing signals on door position to a central process unit of the oven.
Existing door locking systems historically have been very complex in terms of part number count, cost and long tolerance chains. Moreover, different norms for products to be sold in Europe or USA make the design of door locking systems and related switches are not a global one, with a consequence of increasing complexity and cost. The known locking systems are pretty much the same. They all are using a cam wheel movement to activate the switches in the system. These known systems have the disadvantage of being very complex, with a number of pieces ranging from 25 to 40.
It is therefore an object of the present invention to provide a microwave oven with a locking switch system with a very low number of pieces, therefore reducing the overall cost but maintaining or increasing the reliability of the known systems. According to the invention, such object is reached thanks to the features listed in the appended claims.
The technical solution according to the invention have several advantages: a low cost due to a reduced number of parts, a good appearance of the cavity front face, i.e. with no visible fasteners, a high reliability, a process robust design, an expected number of cycles (door open and closed) higher than 100 000, an easy electrical accessibility in production line, and a shorter mechanical tolerance chain.
One of the main features of the solution according to the invention is a single new functional component added to the locking system concept, i.e. a sliding cover element (a sort of moving eyelid) which protects a micro-switch of the system. Such sliding cover element is moved by a dedicated actuator protruding from the rear face of the door, a second actuator protruding from the rear face of the door entering an opening created by the movement of the sliding cover for actuating the micro switch. The sliding movement of the sliding cover element and the actuation of the micro switch are carried out in a close sequence of events. Alternatively the two protruding actuators can be also carried by the body of the oven, and in this case the micro switch is carried out by the door.
According to another feature of the present invention, the system comprises a second micro switch supported by the oven chamber and adapted to be driven by a movable rotating element hinged to the oven chamber and having a portion, in the open configuration of the door, protruding from the chamber.
Further advantages and features according to the present invention will be clear from the following detailed description, with reference to the attached drawings, in which:
With reference to the drawings, an L-shaped component 10 is mounted to the oven chamber front (not shown) so that a side 10a is substantially flush with the annular rim on which the door rest when it is in a closed configuration. On a second side 10b of the component there are mounted three snap-action switches, or micro switches, and particularly a so called primary switch 12, a secondary switch 14 and a monitor switch 16 whose function is well known to the person skilled in the art of microwave oven. For sake of clarity, electrical wires connected to switches have been omitted.
The three above micro switches are rapidly mounted on the component 10 by means of elastic hooks 18 which are obtained integrally with the component (for instance in the injection molding process when the component is made of a polymeric material) and which snap engage the bodies of the micro switches. The secondary and monitor switches 14, 16 are operated by a rotating lever 20 hinged in 22 to the side 10b of the component 10 and having an actuator portion 20a protruding from an aperture 24, in the open configuration of the door shown in
The primary switch 12 is adjacent an elongated rectangular aperture 26 provided in the face 10a of the component 10 which, in the open configuration of the door, is covered, in a zone adjacent the primary switch 12, by a sliding cover or “eye lid” 28. The sliding cover 28 is preferably made of a polymeric material and presents longitudinal rails 28a adapted to slide on corresponding edges 26a of the aperture 26. The rails 28a maintain the sliding cover 28 on the component 10 and, at the same time, allow the longitudinal sliding movement thereof. The retracted position of the sliding cover 18, i.e. when the door is open, is shown in
The sliding cover 28 is maintained in position by a spring 30 interposed between the component 10 and the sliding cover 28. This latter is provided with an opening 32 whose function will be clear from the following description. When the door is closed, a protruding actuator 34 (
From the above description is clear how the number of pieces involved in the design of the switch is extremely low, therefore providing a new way of addressing the mechanical and electrical complexity of a door locking system for a microwave oven. Even if in the above description the sliding cover is associated to the primary micro switch, it could be also associated to any other switch of the switch assembly, for instance the secondary or the monitor switch.
Number | Date | Country | Kind |
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12171920.1 | Jun 2012 | EP | regional |