The present invention relates to a safety module for door-lock device.

More specifically, the invention relates to a module of the above kind, designed and constructed in particular for door-lock devices designed to detect the closure and the lock state of the door of a household appliance, such as a washing machine, a dishwasher and the like, but which can be used for any machine or equipment for which it is necessary to securely block a door.

In the following, the description will be directed to a door-lock device of a household appliance, such as a washing machine, but it is clear that it should not be considered limited to this specific use.

In recent years there has been a progressive development of systems capable of controlling the closing and locking conditions of a door (or appliance door) of a household appliance.

In particular, various technical solutions have been developed, which allow to control the closing of a door with the consequent possibility of operating a lock, for example through an electrically actuated lock, of such door, then verifying the correct lock condition, before the start of the household appliance operating program, for example the washing program, for safety reasons.

In particular, such systems are mainly intended to prevent the washing program from being started, for example, in a washing machine, before or without the door is closed and locked.

The relevant prior art comprises various constructive solutions.

A first drawback of these known solutions consists in the fact that they comprise complex circuit configurations with more than 2 terminals.

Another drawback of these known solutions is that of providing circuit configurations without subparts, which may be considered the standard modules, connected in the electrical circuit in different ways (modular construction of the electrical circuit).

A further drawback of these known solutions consists in the fact that they do not provide particularly compact structures, in contrast with the market requirements, which in fact require compactness, reliability and miniaturization of the components, so that the same can be installed in more and more reduced spaces.

Moreover, a further problem of the solutions according to the prior art is that they do not always allow the use of integrated electronic or electrical devices, which are generally desirable in terms of design, since they make a circuit more robust, reducing the necessary maintenance or breakage risks.

The object of the present invention is to overcome the aforementioned drawbacks of the solutions proposed by the prior art, providing a device for locking a door capable of comprising integrated switches (or interrupters).

Another object of the invention is to provide a door-lock device that includes simple circuit configurations and also a reduced number of components and elements necessary for the realization of the door-lock.

A further object of the invention is to provide a device for locking a door that is highly reliable, relatively simple to manufacture and at competitive costs compared to the prior art.

Another object of the invention is to provide a device for locking a door equipped with a basic circuit component that can be mounted in different electrical configurations, depending on the needs of household appliance control logic, in which the door-lock device is installed.

It is therefore specific object of the present invention a safety module for a door-lock device, intended to block a door of a household appliance, comprising a first terminal, a second terminal, an actuator arranged between said first terminal and said second terminal, a closing switch, provided with contacts, associated with said door of said household appliance and arranged on a closing circuit branch, and a blocking switch, provided with contacts, functionally associated with said actuator and arranged on a blocking circuit branch, wherein said closing circuit branch and said blocking circuit branch are parallel connected to each other, a multiple switch, in its turn comprising a first elastic lamina, which is one of the contacts of said closing switch, a second elastic lamina, which constitutes one of the contacts of said blocking switch, and a common electric support, which said first and said second elastic lamina are coupled to, said multiple switch being made of a single piece, and wherein said closing circuit branch and said blocking circuit branch are series connected to said actuator.

Still according to the invention, said closing switch could comprise a first contact and a second contact, said first contact being connected/disconnected by said second contact, respectively to close or to open said closing switch, and in that said blocking switch comprises a first contact and a second contact, said first contact being connected/disconnected by said second contact, respectively to close or open said blocking switch.

Preferably according to the invention, said first contact of said closing switch could be connected to said first contact of said blocking switch and/or said second contact of said closing switch is connected to said second contact of said blocking switch.

Still according to the invention, one of said contacts of said closing switch and one of the contacts of said blocking switch could be connected via a respective node.

Always according to the invention, said module could further comprise a closing resistor series connected to said closing switch.

Further, according to the invention, said module could further comprise a blocking resistor series connected to said blocking switch.

Advantageously according to the invention, at least one of said closing resistor and said blocking resistor could have a resistance value equal to zero.

Preferably according to the invention, said closing circuit branch and said blocking circuit branch could be parallel connected to said actuator.

Further according to the invention, said closing circuit branch and said blocking circuit branch could be connected to said first terminal or to said second terminal. Always according to the invention, said module could comprise a blocking mechanical assembly of said door of the household appliance, comprising a blocking member of said door such as a latch, a pin, a slider and the like, adapted to engage with said door, so as to lock it while closed, when said blocking switch is closed, and to disengage from said door, when said blocking switch is open.

The present invention will be now described, for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to the figures of the enclosed drawings, wherein:

figure 1 illustrates a first embodiment of the electrical circuit of a safety module for a door-lock device of a household appliance, according to the present invention;

figure 2 illustrates a branch of the circuit of figure 1 realized by means of a basic circuit component of the present invention;

figure 3 illustrates a multiple switch for an implementation of the circuit component for the realization of the door-lock according to the present invention; and

figure 4 illustrates a second embodiment of an electrical circuit of the safety module according to figure 1 using the multiple switch of figure 3.

In the various figures, similar parts will be indicated by the same reference numbers.

With reference to the above-cited figures, the safety module M for a door-lock device to lock a door of a household appliance according to the present invention comprises an electrical circuit.

In general, a door-lock device generally includes a safety module M and a locking mechanical group, to lock the door when closed. The safety module generally detects the state of closure of the door and activates a bolt, or a pin, or a slider and the like, that interfaces with the mechanical blocking unit to lock the door due to several kinematic mechanisms as known in the art. Having a modular construction with separate and integrable safety module and mechanical blocking unit, allows (as is known in the prior art) to adapt a safety module to different mechanical locking units. The electrical circuit of the safety module M substantially comprises a first terminal 1 , a second terminal 2, an actuator 3, a multiple switch 9, comprising in its turn a closing switch 4, associated with the status of the door of the household appliance and therefore cooperating with said door, and a blocking switch 6, functionally associated with the actuator 3, as better described below, a closing resistor 5 arranged electrically in series with said closing switch 4, and a blocking resistor 7 electrically arranged in series to said blocking switch 6.

The two terminals 1 and 2 of said electric circuit are connected, during the operation, to the control logic unit (not shown in the figures) of the household appliance, which provides pulses for driving the actuator 3 and checks the status of the safety module M of the door-lock device by means of suitable voltage (or current) pulses.

More particularly, this control logic unit is configured to verify the impedance detected at the ends of the terminals 1 and 2 to determine the status of the safety module M via a "true table" that associates the different impedance detected values with as many ordinary or anomalous states, e.g. in case of malfunction of the door-lock device.

The normal states are a function of the state (open or closed) of said closing switch 4 and of said blocking switch 6, and therefore of the state of the door and of the actuator 3, which influence these switches.

The actuator 3 is connected between said first terminal 1 and said second terminal 2, and comprises actuating means 31 and an actuating mechanical assembly 32.

Said actuating means 31 comprise a solenoid, but also any other element capable of carrying out a displacement of an object in the space following the application of a voltage and therefore an electric current.

In further embodiments, the solenoid can be replaced by a solution with a shape memory wire, a piezoelectric system, an electric motor, and the like.

In all these cases, a movable part of the actuating means 31 is connected and interfaced to the actuating mechanical assembly 32. This mobile part is, for example, an end of the shape memory wire, an end of a piezoelectric actuator or a rotating shaft of an electric motor.

In case of the actuating means 31 is not a solenoid, it comprises, in turn, a coil (not shown), constituted by a threadlike conductor wound into turns, and a movable core 31 1 , capable of assuming a retracted position, in which at least partially said solenoid 31 is contained, or an extracted position, in which one end of the movable core is further away from the coil, in which said movable core 31 1 actuates said actuating mechanical assembly 32, interfacing with it.

The solenoid 31 can be supplied with different forms of electric power supply, e.g. in a non-limiting way alternate current, direct current or by pulsed current (or for example alternate rectified with diodes, in which the power supply occurs only with half-waves).

The maximum voltage value can be of hundreds of Volt, for example for alternate current applications in the US or EU (by way of example and without limitation to 120V or 220 V) or units or tens of Volt in direct current (such as for example and in a non-limiting way 5V, 12V, 24V, 48V).

In case of direct current power supply, it may be important to define the power supply polarization, namely if to the terminals 1 and 2 a respectively positive and negative voltage, or vice versa, is applied.

In fact, if the movable core 31 1 has a permanent magnetic characteristic, reversing the polarity, there is a movement of the movable core 31 1 from the retracted position to the extracted one and vice versa. The actuating mechanical assembly 32 is capable of decoupling the movement of the actuating means 31 , i.e. the movable core 31 1 , with respect to the movement of the switch 6, in such a way that the position of the movable core 31 1 is not necessarily and univocally with the position of the switch 6.

That is, to a given position of said movable core 31 1 said actuating means 31 may correspond, for example, two positions of the said blocking switch 6.

This type of operation, which is known, allows to have a bistable system, i.e. in which the blocking switch 6 is capable of remaining in a state indefinitely, not imposing a unique state to said actuating means 31 and then to said movable core 31 1 , which therefore can for example remain in two different states.

The foregoing allows not to power supply in a continuous way the actuating means 31 , but to supply them only in the moment in which the state of said blocking switch 6 has to be changed.

In the prior art this system can be achieved in various ways, such as that described in the patent application GB2344849 A, in which the actuating mechanical assembly 32 provides for elements with hooks and cams (as shown in figure 10 of said patent application, these elements, among others, are indicated with the reference numbers 29, 22, 32), which realize a rototranslatory mode or by providing cardioid desmodromic systems, as in US20040104580 A1 (figure VI 3a and figure VI 3b paragraph 0128).

In these examples, a spring is always provided, which allows the movable core 31 1 to return to a rest or initial position after completion of the operation, which follows an electric power supply, contrary to what is achieved by the switch, which remains in one of the two positions in an undefined way.

The actuating mechanical assembly 32 can be realized, as said, in different ways according to the different control modes included in the safety module M, of the circuit electric that can be foreseen.

In any case, said actuating mechanical assembly 32 is capable of assuming an operating position, to which it is brought following a first excitation of said solenoid 31 that causes the extraction of said movable core 31 1 ; and a non-operating position, to which it is brought following a subsequent excitation of said solenoid 31 that causes a subsequent extraction of said movable core 31 1 and therefore the passage to the non operative position of said actuating mechanical assembly 32.

When the actuating mechanical assembly 32 is in said operating position, said blocking switch 6 is closed.

In addition, to said actuating mechanical assembly 32, as anticipated, a mechanical blocking group is further associated, having a locking member (not shown) of the household appliance door, as is known in the prior art. Said mechanical blocking group for locking the door of the household appliance is arranged in such way to engage with said door, so as to block it when closed, when said blocking switch 6 is closed, and to disengage from said door, when said blocking switch 6 is open.

As described above, the multiple switch 9 comprises said closing switch 4 and said blocking switch 6.

The closing switch 4, as mentioned, is associated with the door of the household appliance and is arranged electrically in series with said closing resistor 5, between said first terminal 1 and said second terminal 2, so as to form a closing circuit branch 81 .

Moreover, said closing switch 4 is arranged electrically in parallel with said blocking switch 6.

In particular, the closing switch 4 comprises a first contact 41 and a second contact 42. Said first contact 41 can be connected/disconnected from said second contact 42, on the basis, respectively, of the closing or opening of said closing switch 4.

The blocking switch 6, associated with the actuator 3, is electrically arranged in series to said blocking resistor 7, between said first terminal 1 and said second terminal 2, so as to form a blocking circuit branch 82.

Moreover, said blocking switch 6 is arranged electrically in parallel with said closing switch 4.

The blocking switch 6 also comprises a first contact 61 and a second contact 62. Said first contact 61 can be connected/disconnected from said second contact 62, on the basis, respectively, of the closing or opening of said blocking switch 6.

In an embodiment of the present invention, said first contact 41 of said closure switch 4 is connected to said first contact 61 of said blocking switch 6 and/or said second contact 42 of said secondo switch 4 is connected to said second contact 62 of said blocking switch 6.

Referring to figure 3, said multiple switch 9 includes a first elastic lamina 9a and a second elastic lamina 9b, connected with a common electrical support 9c, wherein said common electrical support 9c form the node 83 and said laminae 9a and 9b respectively form the first contact 41 of said closing switch 4 and the first contact 61 of said blocking switch 6.

Of course, the connection of said multiple switch 9 can be reversed, so that said common electric support 9c forms the node 84. In this case, in a specular way, also the connection of the closing 5 and blocking 7 resistors will be inverted accordingly.

Moreover, as can be seen from figure 3, this common electric support 9c is made as a single piece together with the elastic laminas 9a and 9b.

The elastic laminas 9a and 9b are fixed at one end to said first common electric support 9c, realizing their own electrical contacts and they do not need further return springs, since they themselves are springs, which allow the preferential switch positions.

With particular reference to figure 2, it can be seen that the electrical circuit branch 8 comprises the serial arrangement of the multiple switch 9 and of the parallel connection between the closing 5 and the blocking 7 resistors. This arrangement thus provides the parallel connection between said closing circuit branch 81 , comprising the closing switch 4 and the related closing resistance 5, and said blocking circuit branch 82, including the blocking switch 6 and the associated blocking resistor 7.

As can be seen from figure 1 , in a first embodiment of the present invention, said closing circuit branch 81 and said blocking circuit branch 82 are connected in their turn in parallel with said actuator 3, between said first terminal 1 and said second terminal 2.

This configuration is the most advantageous since the general impedance seen at terminals 1 and 2 is a function of the reciprocal of the impedances of the two resistances. This means that in the moment in which said closing switch 4 and said locking switch 6 are closed, the overall impedance of the system is less than that of the individual impedances reducing the necessary currents for the actuation.

In addition, the aforementioned configuration allows a reduction of the actuation power consumption and is therefore advantageous in terms of energy saving.

The operation of the safety module disclosed in figure 1 for a door- lock device for a household appliance described above is carried out in the following manner.

When the household appliance door is open, the electric circuit of the safety module M according to the invention is in the configuration illustrated in figure 1 .

In this case, both the switches, or said closing switch 4 and said blocking switch 6, are open (i.e. in the "open circuit" condition) and no current flows in the branches of said electric circuit and therefore in the solenoid 31 .

The logic control unit of the household appliance, which is configured to detect the impedance at the ends of said first terminal 1 and said second terminal 2, therefore detects an electrical resistance with a value between said first terminal 1 and said second terminal 2 substantially equal to the resistance of the solenoid 31 (open door condition).

When the user manually closes the door of the household appliance, said closing switch 4 closes, while said blocking switch 6 remains open.

In this case, the control logic unit of the household appliance detects an electrical resistance given by the value of the internal resistance of said solenoid 31 in parallel with said closing resistor 5, between said first terminal 1 and said second terminal 2 (door condition closed but not blocked).

Subsequently, following a command from a user, such as for example pressing a button on the household appliance, the control logic unit of the household appliance sends an electrical signal to the ends of said first 1 and second 2 terminal.

This electrical signal has a voltage such as to operate said actuator 3.

In particular, this electrical signal excites said solenoid 31 , causing said movable core 31 1 to pass from said retracted position to said extracted position, thus causing the passage of said actuating mechanical assembly 32 from a non-operative position to the operative position, thus causing in its turn the closure of said blocking switch 6.

Said actuating mechanical assembly 32 remains in said operating position thus keeping said blocking switch 6 closed, while the movable core example, a return spring not indicated and characteristic of the prior art as indicated in the patents GB2344849 A and US20040104580A1 and therefore known per se.

Moreover, at the same time, the mechanical locking assembly (not shown in the figures but known per se) of the household appliance door is activated by a system, which is integral or cooperating with the blocking switch 6, such that said the door is thus blocked when closed.

At this point, the control logic unit of the household appliance detects an electrical resistance of a value equal to the internal resistance of said solenoid 31 in parallel with the value of the resistance given by the parallel electrical arrangement of said blocking resistor 7 and said closing resistor 5, between said first terminal 1 and said second terminal 2 (closed and blocked door condition), so that the control logic unit can safely start the operating program of the household appliance, being the door closed as well as also blocked.

Finally, to obtain an opening of said blocking switch 6, and therefore to return to the closed but not blocked door condition, the control logic unit sends a further electrical signal so as to energize again the solenoid 31 , thus extracting again the movable core 31 1 , which causes said actuating mechanical assembly 32 to pass from said operating position to said non operating position, thus opening the blocking switch 6.

As an alternative to the group constituted by said actuating means 31 and said actuating mechanical assembly 32, an electric actuation system can be had, for example a system with one or more coils, in which there is a permanent magnetic system, wherein it is the polarity inversion of the voltage applied between the terminals 1 and 2 to modify the position of the blocking switch 6 and therefore of the latch associated with it.

The invention described herein has the advantage (because of the actuating mechanical assembly 32) of not requiring the inversion of the polarity to change the state of the door-lock by the control unit logic.

The control logic unit, therefore, detecting the impedance of the closing resistance 5 only in combination with that of the actuating means 31 , detects that the door has been unlocked. The original condition of an open door is therefore achieved through a subsequent manual opening of the door of the household appliance by the user, which obviously also causes the opening of said closing switch 4.

With particular reference to figure 4, a further embodiment of the door-lock device according to the present invention can be seen. As can be seen, the circuit branch 8 is similar to that of the embodiment according to figure 1 .

In said further embodiment of the present invention, said closing circuit branch 81 and said blocking circuit branch 82 are connected in series with said actuator 3 through said node 84.

The operation of said further embodiment is similar to that of the embodiment shown in figure 1 and described above.

In particular, the aforesaid embodiment is an alternative to the first embodiment, in that said closing resistor 5 and said blocking resistor 7 are electrically connected in series with the impedance of said actuator 3.

Although this construction is advantageous in terms of layout (there are fewer intersection points in the electrical circuit), it is disadvantageous in terms of electrical consumption of the door-lock device. A compromise between these two contrasting aspects has to be found based on the particular application.

In alternative embodiments of the present invention, at least one of said closing resistor 5 and said blocking resistor 7 has a resistance value equal to zero, for example and in a non-limiting way if other electronic components are used to vary the impedance.

In practice, it has been found that the present invention fully achieves the intended aim and objects. In particular, it has been seen how the door- lock device thus conceived allows to overcome the qualitative limits of the prior art, since it allows to include integrated switches (or interrupters).

Another advantage of the door-lock device according to the present invention is that it comprises simple circuit configurations.

The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiments, but it is to be understood that modifications and/or changes can be introduced by those skilled in the art without departing from the relevant scope as defined in the enclosed claims.