Control circuit for actuating a locking device for household appliances and device comprising said circuit

Abstract

The present invention relates to a locking device of a household appliance door comprising a circuit having a first, a second and a third connecting contacts to the household appliance, the device comprising a door locking switch, a door closing switch and an actuator arranged electrically in series with said door closing switch, at least one diode and at least one control switch on said third contact and electrically in series with said actuator. By virtue of this configuration, the locking and the unlocking of the door may be controlled by specific, different predetermined electrical pulses.

Claims

1. A control circuit for a locking device of a household appliance having a first branch connected to a first connecting contact (1), a second branch connected to a second connecting contact (2) and a third branch connected to a third connecting contact (3) of the household appliance, the device comprising: a door locking switch (DL) arranged on said first branch connected to said first contact (1); a door closing switch (DS) arranged on said second branch connected to said third contact (3) and electrically in series with said locking switch (DL); an actuator (4), arranged electrically in series with said door closing switch (DS); at least one diode (D, D1, D2) and at least one control switch (SW, SW.sub.A, SW.sub.B) arranged electrically in series between said third contact (3) and said actuator (4); wherein the at least one control switch (SW.sub.A), the at least one diode (D), and a further switch (SW.sub.B) are arranged electrically in series between said third connection contact (3) and said actuator (4).

2. A circuit according to claim 1, characterized in that it comprises a fourth circuit branch (A) which comprises a first pole (A.sub.1) and a second pole (A.sub.2), said second pole (A.sub.2) being connected to said third connecting contact (3), and in that said third circuit branch comprises a first pole (B.sub.1) of said third branch and a second pole (B2) of said third branch, arranged between said first pole (B1) and said actuator (4).

3. A circuit according to claim 1, characterized in that said actuator (4) is formed by a solenoid.

4. A control circuit for a locking device of a household appliance having a first branch connected to a first connecting contact (1), a second branch connected to a second connecting contact (2) and a third branch connected to a third connecting contact (3) of the household appliance, the device comprising: a door locking switch (DL) arranged on said first branch connected to said first contact (1); a door closing switch (DS) arranged on said second branch connected to said third contact (3) and electrically in series with said locking switch (DL); an actuator (4), arranged electrically in series with said door closing switch (DS); first and second diodes (D1, D2); and at least one control switch (SW) arranged electrically between said third contact (3) and said actuator (4); wherein said first diode (D1) and said second diode (D2) being electrically in parallel with each other and arranged between said third contact (3) and said control switch (SW), said control switch (SW) being selectively switchable between said first diode (D1) and said second diode (D2), thus realizing an electrical contact in series between said third contact (3) and said actuator (4).

5. A circuit according to claim 4, characterized in that said actuator (4) is formed by solenoid.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Further features and advantages of the present invention will be more apparent in the following detailed description provided by way of nondimitative example and illustrated in the accompanying figures, in which:

(2) FIGS. 1 to 3 show examples of door locking circuits of the known type of the prior art;

(3) FIG. 4 shows a first embodiment of an electrical circuit diagram of the locking device according to the present invention;

(4) FIG. 5 shows a second embodiment of an electrical circuit diagram of the locking device according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) With particular reference to FIG. 4, the device according to the present invention comprises three connecting contacts to the household appliance, in particular a first contact 1, a second contact 2 and a third contact 3.

(6) Following the electric circuit diagram shown in FIG. 4 starting from said first connecting contact indicated by 1, the device comprises a locking switch DL of the door, arranged electrically in series on said connecting contact 1.

(7) The branch connected to the second contact 2 is electrically in series with the first branch connected to said first contact 1.

(8) A third branch connected to said third contact 3 and is connected with said first branch connected to the first connecting contact 1, and an actuator 4 and a door closing switch DS are arranged in series on said second branch.

(9) In the described general diagram, said actuator 4 may preferably consist of a solenoid valve, and in such a case the device will be supplied with alternating current.

(10) The locking device described above operates as follows.

(11) When the door of the household appliance is open, the circuit of the device is in the configuration of FIG. 4, in which both switches, i.e. the door closing switch DS and the door locking switch DL, are open.

(12) In this configuration, the control electronics of the household appliance detects the door opening condition deriving from the opening of the closing switch DS.

(13) When the user manually closes the household appliance door, the closing switch DS is closed and the control electronics thus detects the closing of the circuit between the second 2 and third 3 connecting contact.

(14) In accordance to a first embodiment of the device according to the present invention, at least one control switch SW and at least one diode D are interposed between said third connecting contact 3 of the circuit of the household appliance and said actuator 4.

(15) More in detail, according to the embodiment shown in FIG. 4, a first diode D1 and a second diode D2 are arranged electrically in parallel between said third contact 3 and said actuator 4 together with a control switch SW, which allows to connect said actuator 4 to said third connecting contact 3 in series selectively by means of either said first diode D1 or said second diode D2.

(16) Therefore, the operation of the device thus configured is the following.

(17) In the opening condition of the household appliance door, the closing switch DS on the second branch is open, and the locking switch DL on the first branch is also open, the control switch SW is in contact with the first diode D1, as shown in FIG. 4.

(18) When the door is closed and the closing switch DS closes, the actuator 4 may be supplied with current because the circuit is closed between the second connecting contact 2 and the third connecting contact 3.

(19) At this point, the control electronics of the household appliance sends an electrical locking pulse in input to the third connecting contact 3.

(20) According to a preferred embodiment of the present invention, said first diode D1 allows the passage of an electrical pulse consisting of a positive half wave. Only such pulse can thus activate said actuator 4, because it can cross said first diode D1.

(21) At this point, the actuator 4 can close the locking switch DL and switch the control switch SW on said second diode D2.

(22) In this configuration, both switches DS and DL are thus closed, the control unit detects a door closing and locking condition and the control switch SW closes the branch connected to the third connecting contact 3 on said second diode D2.

(23) Said second diode D2 will be advantageously configured to allow the passage of an electrical unlocking pulse, consisting of a negative half wave in this case.

(24) In this manner, in the condition described above corresponding to a door closing and locking configuration, only a negative half wave pulse may activate the actuator 4 because only such a pulse may cross the circuit branch on which it is positioned, between said third connecting contact 3 and said control switch SW, said second diode D2.

(25) A negative half wave pulse thus operates the actuator 4 which opens the locking switch DL allows the manually opening of the door and the consequent opening of the closing switch DS, said actuator 4 controlling said control switch SW, which is returned to closing on said first diode D1, at the same time.

(26) By virtue of the device according to the present invention illustrated hereto, it is thus possible to control the locking and the unlocking of the locking switch DL, which allows the subsequent opening of the door by the operator, by means of a well-defined electrical pulse chosen during the step of designing, thus overcoming the inherent limit of devices of the known type consisting in that it is not possible to achieve a univocal correspondence between electrical pulse supply to the circuit and the action performed by the actuator 4.

(27) Indeed, with the devices of traditional type, an action of the actuator 4 always corresponds to an electrical pulse arriving to the actuator 4 itself which switches the state of the unlocking switch DL from the current state to the opposite state: it closes it if it was open and opens it if it was closed.

(28) With reference to FIG. 5, a second preferred embodiment of the device according to the present invention will now be illustrated, in which the circuit has, similarly to the case described above with reference to FIG. 4, a first 1, a second 2 and a third 3 connecting contacts of the circuit of the household appliance device, a closing switch DS arranged in series with an actuator 4 on the second connecting branch to said third contact 3, a locking switch DL arranged on the first branch and electrically in parallel to said third branch.

(29) At least one diode D and at least two control switches SW.sub.A and SW.sub.B are preferably arranged between said third connecting contact 3 and said actuator 4.

(30) In the embodiment illustrated in FIG. 5, following the circuit starting from said third connecting contact 3, a first control switch SW.sub.A, a diode D, and a second control switch SW.sub.B are arranged in series between said third connecting contact 3 and said actuator 4.

(31) Said third connecting contact 3 is connected to a second pole A.sub.2 of a fourth circuit branch A which ends with a first pole A.sub.1 of said fourth branch A.

(32) Said second branch of the circuit on which said actuator 4 and said closing switch DS are present is connected with a first pole B.sub.1 of the third branch, which a second pole B.sub.2 of said third branch is arranged between said first pole B.sub.1 and said actuator 4.

(33) With reference to FIG. 5, said first control switch SW.sub.A may be switched between said first pole A.sub.1 of said fourth branch A and said first pole B.sub.1 of said third branch, while said second control switch SW.sub.B may be switched between said second pole A.sub.2 of said fourth branch A and said second pole B.sub.2 of said third branch.

(34) Said diode D is arranged in series between said first control switch SW.sub.A and said second control switch SW.sub.B.

(35) The operation of the circuit of the device according to the present invention and according to this second preferred embodiment is the following.

(36) When the door of the household appliance is open, the circuit of the device is in the configuration of FIG. 5, in which both switches, i.e. the door closing switch DS and the door locking switch DL, are open.

(37) In this configuration, the control electronics of the household appliance detects the door opening condition deriving from the opening of the closing switch DS.

(38) When the user manually closes the household appliance door, the closing switch DS is closed and the control electronics thus detects the closing of the circuit between the second 2 and third 3 connecting contacts.

(39) Said first control switch SW.sub.A is closed on said first pole B.sub.1 of said third branch, and said second control switch SW.sub.B is closed on said second pole A.sub.2 of said fourth branch A.

(40) In this manner, the current pulse which reaches the circuit from the third connecting contact 3 passes from said second pole A.sub.2 of said fourth branch A, crosses said second control switch SW.sub.B, through the diode D and reaches the actuator 4 through the first pole B.sub.1 of said third branch.

(41) By virtue of this configuration, the circuit may be supplied with a positive half wave looking pulse; indeed, only such a pulse can activate the actuator 4, because it is the only pulse which can cross the diode D.

(42) According to a possible alternative embodiment, obviously said diode D could be configured in a manner so as to allow the passage of a negative half valve electrical pulse.

(43) When the actuator 4 is supplied by the current, it operates, as occurs in the embodiment shown in FIG. 4, both the locking switch DL and the first SW.sub.A and the second SW.sub.B control switches.

(44) In particular, said actuator causes the closing of the locking switch DL and switches the first control switch SW.sub.A on said first pole A.sub.1 of said fourth branch A and said second control switch SW.sub.B on said second pole B.sub.2 of said third branch.

(45) In this configuration, both switches DS and DL are closed, the control electronics of the household appliance detects a door closing and locking condition and the control switches SW.sub.A and SW.sub.B close the electrical connection between said third connecting contact 3 and said third branch allowing the passage of an unlocking pulse, in particular in the supplied example this is a negative half wave pulse which in the provided example, can reach and operate said actuator 4.

(46) A negative half wave pulse thus operates the actuator 4 which opens the locking switch DL allows the manual opening of the door and the consequent opening of the closing switch DS, said actuator 4 controlling said control switch SW which is returned to closing on said first diode D1 at the same time.

(47) We have thus demonstrated that by virtue of the device according to the present invention illustrated hereto it is possible to control the locking and the unlocking of the locking switch DL which allows the subsequent opening of the door by the operator, by means of an electrical pulse of known, predetermined nature, thus overcoming the inherent limit of devices of the known type consisting in that it is not possible to achieve a univocal correspondence between electrical pulse supplied to the circuit and the action performed by the actuator.