Patent ID: 12188263

It should be noted that in the drawings some components have been removed to show more clearly the relevant aspects of the embodiments.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, the reference number10indicates an electromagnetic door lock for locking the door of a domestic appliance, in particular a washing machine. The door lock10comprises a rotating cam12, which rotates about a first axis A between an open-door position (FIG.1) and closed-door position (FIG.2). The rotating cam12cooperates with a hook14fixed to a door (not shown) of a domestic appliance. The hook14engages the rotating cam12in the open-door position ofFIG.1and, during closure of the door, causes the rotating cam12to rotate about the first axis A to the closed-door position shown inFIG.2. In the closed-door position the rotating cam12is engaged with the hook14and holds the door of the appliance in a closed position.

The door lock10comprises a locking device16arranged to lock the rotating cam12in the closed-door position. The locking device16comprises a main lever18rotatable about a second axis B and a rocker arm20rotatable about a third axis C. The rocker arm20has a surface22in contact with the rotating cam12. The main lever18cooperates with the rocker arm20and biases the rocker arm20in contact with the rotating cam12.

The locking device16includes an electromagnetic actuator24. With reference toFIGS.3and4, the electromagnetic actuator24has a solenoid core26movable between a retracted position (FIG.3) and an extended position (FIG.4). A cam element28is attached at the distal end of the solenoid core26. A locking pin30cooperates with the cam element28and moves between an unlocking position (FIG.3) corresponding to the retracted position of the solenoid core26and a locking position (FIG.4) corresponding to the extended position of the solenoid core26.

When the locking pin30is in the locking position it engages a surface32of the main lever18and prevents a rotation of the main lever in an anticlockwise direction. An attempt to open the door, e.g. by the user of appliance, causes the main lever18to rotate in counterclockwise direction, as indicated by the arrow D inFIG.4. The locking pin30prevents a rotation of main lever18, so it is impossible to open the door. Therefore, in this condition the rotating cam12is locked in the closed-door position.

With reference toFIGS.1,2and5, the door lock10comprises a door sensing device34. The door sensing device34includes a door sensing element36movable between a first position (FIG.1) and a second position (FIGS.2and5) corresponding, respectively, to the open-door position and to the closed-door position of the rotating cam12. The door sensing device34may include a door sensing lever38which may be rotatable about an axis E and a door sensing slider40connected to the door sensing lever38and to the door sensing element36.

As shown inFIGS.1and2, the rotating cam12is in contact with the door sensing lever38. The rotation of the rotating cam12from the open-door position to the closed-door position causes a rotation of the door sensing lever38about the axis E, which in turn causes—through the door sensing sider40—a movement of the door sensing element36from the first position to the second position.

The movement of the door sensing element36from the first position to the second position may be a rotation about an axis F.

With reference toFIGS.1,2and5, the door lock10comprises a first contactless proximity sensor42which detects the second position of the door sensing element36.

In one or more embodiments, the door lock10comprises a second contactless proximity sensor44which detects the locking position of the locking pin30.

The first or the second contactless proximity sensor42,44may be carried by a stationary support46, for instance a printed circuit board. The first or second contactless proximity sensor42,44may cooperate with at least one respective actuating element48,50carried by the door sensing element36or by the locking pin30.

The first and the second contactless proximity sensor42,44replace the electromechanical switches of the prior art solutions. The first and the second contactless proximity sensor42,44may be magnetic sensors, like Hall sensors, magnetoresistive (MR) sensor, optical sensors and the like.

The description of the exemplary embodiment and the accompanying drawings are based on magnetic sensors, but the invention is not limited to them. In one or more embodiments, sensors based on other principles can be implemented to sense the relative positions of movable and non-movable parts in the door lock10.

In case of sensors based on magnetic principle of operation, the actuating elements48,50are preferably made of magnetic or magnetizable material, for example permanent magnets, but may also be made of other materials suitable for detection by the contactless proximity sensors42,44. The magnets can be fixed to the respective supports, for example door sensing element36or locking pin30, by snap-fixation, gluing, over-molding or other suitable processes.

Preferably, the contactless proximity sensors42,44are carried by a stationary support46, e.g. a printed circuit board, as shown in the drawings, which can contain also other electronic or electromechanical elements needed for the operation of the sensors42,44. The part carrying the sensors42,44can contain other electronic elements needed for its operation and preferably contains connections to connect electrical signals to the control unit of appliance. The sensors42and44can be carried by a single printed circuit board46(as shown in the described embodiment) or by two separate printed circuit boards, depending on the applications.

The basic principle of operation is the same for all pairs sensors/actuating elements in the door lock10. In case of sensors based on magnetic principle of operation, the magnetic field of the magnets48,50is detected by a sensing surface of the respective sensor42,44. Because of this influence, the output of the sensor changes its state. Depending on the type of sensors and respective electronic elements, the output of the sensors can be digital or analogue. In case of digital output, the output of each sensor42,44has two discrete values in case of presence or absence of a magnet48,50.

The shape of the magnets48,50can be rectangular, tubular or the like. In the positions when the magnetic fields of the magnets48,50influences the sensing area of the respective sensors42,44the areas of the magnets48,50which generate magnetic field and the sensing areas of the sensors42,44are in close proximity and positioned so that the sensing areas of the sensors42,44is preferably parallel to the respective surfaces of the magnets48,50which generate the magnetic fields.

The sensors42,44are preferably carried by a part of door lock10which does not move during the operation of door lock, while the magnets48,50are preferably carried by parts which are movable during the operation of door lock10, for example movable linearly or rotatable or a combination of both. This description is not limiting as depending on specific execution of door lock10. For instance, the relative position of the sensors and magnets may be inverse, so the sensors may be carried by movable parts and the magnets by non-movable parts.

The first proximity sensor42provides an information on whether the door of the appliance is open or closed. In some cases it may be required to know also an intermediate position of door, for example door partly open. This position of the door enables constant venting of drum of appliance, for example a washing machine, and can be required in case of automatic door opening of, for example, washing machines. In this case, after the washing cycle, the door of the appliance would be opened for a certain angle automatically or by manual action of user, but the hook14would still be engaged with rotating cam12. In this situation door lock10would be neither in an open door or closed door position but would be in partly open position. In case of analogue output, the sensor enables to sense also intermediate positions of the moving element carrying the magnet48,50relatively to sensor, enabling for example the possibility to sense a partially closed-door position, which can be advantageous for example to sense a partially open position of the door needed for venting the drum of the washing machine when it is not operating.

After the start of the cycle of the appliance, for example in case of washing machine a washing cycle, the appliance control unit generates an activating pulse to the electromagnetic actuator24and as the result solenoid core26moves to the extended position. As a result, the magnet50carried by the locking pin30, reaches its “locked” position and influences the sensing area of the second proximity sensor44carried by the printed circuit board46. As a result, the output of the second sensor44changes as compared to the previous “unlocked” condition and corresponds to a “locked” condition. This information, generated directly by the sensor or through elaboration of the signal by the electronic parts on the printed circuit board46, is available to control unit of appliance, signaling a “locked” condition of the door lock10.

In the embodiment shown inFIGS.1to4, each sensor42,44cooperates with only one magnet48,50.FIG.5shows an alternative embodiment in which each of the contactless proximity sensors42,44cooperates with two magnets48′,48″ and50′,50″. This solution may be required in particular due to the following reasons:a) In certain positions of the door sensing element36or locking pin30, the magnetic fields of the magnets48or50do not influence the sensing areas of the sensors42,44, respectively. In the absence of magnetic field of the magnets48or50, external magnetic fields can influence and disturb the function of the sensors42or44. This can be for example caused by magnetic fields generated by electric motors, microwaves, mobile phones or other devices. To increase immunity of the sensors42and44to such external magnetic influences, a second magnet can be added onto door sensing element36and/or locking pin30.b) Certain type of sensors42,44may require a change of the magnetic field influencing their sensing areas. More particularly, in order to change the output of the sensors42,44, a change of the polarity of the magnetic field influencing their sensing area, from positive to negative or vice versa, may be required.

In the embodiment ofFIG.5, the door sensing element36and/or the locking pin30carries a first and a second actuating element48′,48″ or50′,50″. The first and second actuating element48′,48″ or50′,50″ may be magnets with opposite polarities.

In the open door position the sensing area of the sensor42is influenced by the magnetic field of a first magnet48′, which has a first polarity, for example south. In the closed door position the sensing area of sensor42is influenced by the magnetic field of a second magnet48″ which has a second polarity, for example north.

In the same way, in the unlocked door position the sensing area of the sensor44is influenced by the magnetic field of a first magnet50′, which has a first polarity, for example south. In the locked door position the sensing area of sensor44is influenced by the magnetic field of a second magnet50″, which has a second polarity, for example north.

In case of sensors based on magnetic principle of operation, to increase immunity to external magnetic fields which may influence the proper operation of the sensors, some parts of the door lock10can be made of electrically conductive material to provide shielding. For example, this can be applied to housing and cover (not shown in the drawings).