DOOR LOCKING DEVICE FOR HOUSEHOLD APPLIANCES

Abstract

The present invention relates to a door locking device (1) for household appliances. The device according to the present invention allows to detect a door closing or opening condition, to actuate, only with the door closed, an electromagnetic actuator (40) that triggers door locking means and a respective switch (50), and finally to detect the door locking condition. The operation of the door lock required by current safety standards is obtained here by means of an architecture of the door lock which allows to simplify the architecture of the door lock itself, in particular by reducing the connecting contacts (10, 20) with the household appliance to only two.

Claims

1. A locking device of a household appliance door, having a first and a second connecting contact to the household appliance, the device comprising a door closing switch arranged on said first contacts; an actuator arranged electrically in series with said door closing switch; a door locking switch arranged electrically in series between said actuator and said second contact; a resistor, arranged between said actuator and said second connecting contact and electrically in parallel to said door locking switch.

2. A device according to claim 1, characterized in that said actuator is formed by a solenoid.

3. A device according to claim 2, characterized in that said resistor is formed by a PTC.

4. A device according to claim 1, characterized in that said actuator is formed by a shape-memory element.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0041] Further features and advantages of the present invention will be more apparent in the following detailed description provided by way of non-limitative example and illustrated in the accompanying figures, in which:

[0042] FIGS. 1 to 3 show examples of door locking circuits of the known type of the prior art;

[0043] FIG. 4 shows an electric circuit of the locking device according to the present invention in an operating condition in which the door is open;

[0044] FIG. 5 shows the same diagram in FIG. 4 in an operating condition in which the door is closed but not locked;

[0045] FIG. 6 shows the same diagram in FIG. 5 in an operating condition in which the door is closed and locked.

DETAILED DESCRIPTION OF THE INVENTION

[0046] With particular reference to FIG. 4, the device 1 according to the present invention comprises only two connecting contacts to the household appliance, in particular a first contact 10 and a second contact 20.

[0047] Following the electric circuit diagram shown in FIG. 4 starting from said first connecting contact indicated by 10, the device 1 comprises a closing switch 30 of the door and an actuator 40, arranged electrically in series with said closing switch 30 on said first contact.

[0048] Continuing to follow the circuit starting from the first contact 10, the device 1 according to the present invention further comprises a door locking switch 50 arranged electrically in series between said actuator and said second contact 20.

[0049] The device 1 according to the present invention further comprises a resistance 60 arranged between said actuator 40 and said second connecting contact 20, said resistance 60 being arranged electrically in parallel to said door locking switch 50. In the described general diagram, said actuator 40 may preferably consist of a solenoid valve, and in such a case the device will be supplied with alternating current. Alternatively, said actuator 40 may consist of an element made of memory-shape material, e.g. a wire, and in such a case the actuator may be actuated by supplying the circuit with direct current.

[0050] With regards to the resistance 60, if the circuit includes a solenoid as actuator 40, said resistance may consist of a PTC, i.e. a ceramic element arranged to protect the solenoid, as known to a person skilled in the art.

[0051] If instead the circuit includes a memory-shape wire or other element as actuator 40, the PTC may not be provided and any electric resistance may be provided in its place.

[0052] The locking device described above operates as follows.

[0053] When the door of the household appliance is open, the circuit of the device 1 is in the configuration of FIG. 4, in which both switches, i.e. the door closing switch 30 and the door locking switch 50, are open.

[0054] In this configuration, the control electronics of the household appliance detects the open door condition deriving from the opening of the closing switch 30 at the terminals of the first 10 and of the second 20 connecting contacts.

[0055] When the user manually closes the door of the household appliance, the closing switch 30 is closed and the control electronics thus detects an electric resistance given by the sum of the resistances determined by the presence of the actuator 40 and of the resistance 60, as shown in FIG. 5, between the first 10 and the second 20 connecting contacts.

[0056] At this point, the control electronics sends an electric signal capable of actuating the actuator 40 which closes the locking switch 50, as shown in FIG. 6.

[0057] The control electronics of the household appliance exclusively detects a difference of potential associated to the presence of the actuator 40 only at this point between the first 10 and the second connecting contacts 20 and can thus check the door closing and locking condition.

[0058] In order to obtain the opening of the locking switch 50 at the end of the operating cycle of the household appliance it is sufficient to provide a new pulse to the solenoid which, from the condition in FIG. 6, may reopen the locking switch 50 thus returning the circuit in the configuration in FIG. 5.

[0059] We have thus shown that the door locking device according to the present invention reaches the suggested purpose and objects.

[0060] In particular, we have shown that the door locking device according to the present invention allows to reduce the connecting contacts of the device itself to the household appliance to only two.

[0061] In addition to the apparent advantages in the overall dimensions of the device itself, this simpler, more compact configuration also provides considerable advantages in terms of cost-effectiveness deriving both from the lower production costs of the device itself and from the lower number of wires which need to be arranged in the household appliance.

[0062] Many changes may be made by a person skilled in the art without departing from the scope of protection of the present invention.

[0063] The scope of protection of the claims, therefore, must not be limited to the illustration or preferred embodiments described by way of example, but rather the claims must include all the features of patentable novelty inferable from the present invention, including all the features that would be treated as equivalent by a person skilled in the art.