WO2012012408A1

WO2012012408A1 - Blocking device for the door of an electric household appliance, in particular the door of a pyrolytic oven

Info

Publication number: WO2012012408A1
Application number: PCT/US2011/044511
Authority: WO
Inventors: Dino Chirumbolo
Original assignee: Illinois Tool Works Inc.
Priority date: 2010-07-20
Filing date: 2011-07-19
Publication date: 2012-01-26
Also published as: IT1401740B1; ITTO20100625A1

Abstract

A blocking device (1) for a door (4) of an electric household appliance including a support (5), associable in use to a casing of the electric household appliance, a striker (6) associable in use to a door, engaging means (7) for the striker carried by the support movable between a first and a second position, in the latter being adapted to engage in use the striker (6), with the door being closed, for opposing its departure from the support, and electromagnetic means (8) for blocking the engaging means in the second position; wherein the engaging means consist of a fork shaped element (10) rotatably carried by the support, and a spring (11) eccentrically secured to the rotation axis of the fork shaped element, between the latter and the support, so as to stress the fork shaped element to selectively take the first and second positions; and wherein the electromagnetic blocking means include: a slider (12) carried in sliding manner between a first and a second position, only in the latter the slider intercepting the fork shaped element (10) for preventing the rotation thereof; a push-push mechanism (13) carried by the support and adapted to selectively make the slider to make the assume the first and second position; and an electromagnetic (14) to selectively actuate the push-push mechanism (13).

Description

BLOCKING DEVICE FOR THE DOOR OF AN ELECTRIC HOUSEHOLD APPLIANCE, IN PARTICULAR THE DOOR OF A PYROLYTIC OVEN

The present invention relates to a blocking device for the door of an electric household appliance, in particular adapted to block the door of a pyrolytic oven in closing position.

It is known that in many types of household appliances, e.g. washing machines, dishwashers and pyrolytic ovens, the door of the electric household appliance must be blocked in the closing position during the operation of the electric household appliance itself, in order to prevent the user from accidentally opening the door. In particular, pyrolytic ovens are ovens capable of running a self-cleaning cycle in addition to the normal cooking cycles, in which the oven reaches temperatures much higher than during normal operation (thus potentially dangerous for the user) in order to eliminate particles of dirt (e.g. grease) present on the walls of the oven by pyrolysis, hence the name. At least during the running of such a self- cleaning cycle, the oven door must remain blocked in absolutely reliable manner.

The known blocking devices for doors of pyrolytic ovens are usually actuated by servo motors, and are conseguently very costly. More in general, the known blocking devices for doors of pyrolytic ovens are relatively cumbersome and have a complex structure . Furthermore, it would be desirable to improve the gas tightness of the door edge, usually provided with a gas seal arranged so as to cooperate frontally in use with the door closed between the peripheral edge of the door and the door abutting frame carried by the casing of the electric household appliance.

Finally, the need is felt to have a blocking device for doors which is reliable, capable of working also on electric household appliances the electronic control board of which is not in the most sophisticated class (class C) .

It is an object of the present invention to solve the described drawbacks by providing a blocking device for doors of low cost, small dimensions, and high structural simplicity, which works in absolutely reliable manner with any electronic control board the electric household appliance is fitted with, and which, at the same time, can ensure optimal gas tightness at the door edge, in particular during execution of the pyrolysis function without reguiring a high effort on behalf of the user to open and/or close the door.

The present invention thus relates to a door locking device for an electric household appliance, in particular a pyrolytic oven, as disclosed in claim 1.

In particular, the device according to the invention comprises a support, associatable in use to a casing of the electric household appliance, a striker associatable in use to a door of the electric household appliance, engaging means for the striker carried in a movable manner between a first and a second position by the support, in the latter position the engaging means being adapted to engage in use, with the door closed, the striker for contrasting the movement thereof away from the support, and electromagnetic means for blocking the engaging means in the second position, and conseguently blocking the door in the closing position.

According to the main feature of the invention, the engaging means consist in a bistable system, comprising a fork shaped element rotatably carried about an axis by the support, and a spring eccentrically secured with respect to the rotation axis of the fork shaped element, between the latter and the support, so as to stress the fork shaped element to selectively assume the first and the second position by means of rotation of one towards the other, and vice versa; and in combination the electromagnetic blocking means comprise: a slider slidingly carried between a first and a second position, only in the latter the slider intercepting the fork shaped element for preventing the rotation thereof; a push-push mechanism carried by the support and adapted to selectively make the slider assume the first and the second position; and an electromagnet to selectively actuate the push-push mechanism.

The push-push device may be of any known type actuatable by electromagnetic means, e.g. of the type used in door blocking device (for a washing machine) described in patent EP2167717.

According to an aspect of the invention, the spring is a helical spring secured so that an actuating axis thereof is arranged transversally to the rotation axis of the fork shaped element and directed so that, in the second position of the fork shaped element itself, it applies in use to the door, by means of the striker, a stress which compresses a peripheral seal of the door.

Furthermore, the fork shaped element is provided with a cantilever element arranged radially protruding therefrom at an angular position such that, when the fork shaped element passes from the first position to the second position by means of a rotation, the slider may be engaged below the cantilever element; in particular, the slider cooperates with the radial cantilever element of the fork shaped element through an inclined plane, so that, when both the slider and the fork shaped element are in the respective second position, the slider applies a tangential stress to the fork shaped element, which stress pushes in use the door towards a peripheral seal of the door by means of the striker .

Finally, the door blocking device according to the invention includes a safety door lock device carried by the support in a position facing the slider and comprising a latch moveable between a retracted position in a seat of the safety door lock device and an extracted position from the seat, and wherein it is adapted to intercept the slider when this is in the second position to block it therein; and electric actuating means for the latch.

In this manner, a constructively simple, functional and compact blocking device for doors is obtained, which may use known components normally used in devices of other type, and which, already when the door is closed and not yet blocked, exerts on the peripheral seal of the door a pressure independent of that of the possible contrast spring of the door of the electric household appliance itself, ideal to ensure good tightness with regards to the gases which are developed in the oven.

Such a pressure is then further increased when the door is blocked in the closed position, i.e. precisely when during the execution of the pyrolysis function which develops most of the possible gas.

Furthermore, by means of an appropriate electronic control of the electromagnetic actuator, it is possible to make the door blocking absolutely safe, by reguiring, for example, a double pulse for energizing of the electromagnet to actuate the push-push device when the slider is to be returned to the first position. In all cases, the same device, also in absence of an appropriate electronic control of the electromagnet remains absolutely safe and reliable by virtue of the presence of the supplementary safety blocking device, which maintains the slider blocked in the second position independently of the actuation of the push-push device by the electromagnetic actuator, for the entire duration of the pyrolysis function, it being sufficient for such a purpose to maintain powered the electric actuator means of the latch, which preferably comprise a PTC pill.

Further features and advantages of the present invention will be apparent from the following description of a preferred embodiment thereof, exclusively provided by way of non-limitative example, with reference to the accompanying drawings, in which:

- figure 1 shows in diagrammatic form an axonometric three-guarters front view from the top and partially in section of a blocking device for doors according to the invention applied to an electric household appliance, in a first operating position in which a door of the electric household appliance is open ;

- figure 2 shows in diagrammatic form the device of the invention in the same view in figure 1 applied to the same electric household appliance but shown in a second operating position, in which the door of the electric household appliance is closed; and

- figure 3 shows in diagrammatic form the device of the invention in the same view in figure 1 and 2, illustrated in a third working position, in which the door of the electric household appliance is closed and blocked .

With reference to figures from 1 to 3, numeral 1 shows as a whole a door blocking device for an electric household appliance, in particular a pyrolytic oven, of which only part of a casing or body 2 of the same is shown for the sake of simplicity delimiting a service compartment 3 closed in use by a pivoting door 4 (figures 2 and 3) which, in certain conditions, must be blocked to prevent the manual opening thereof .

For this purpose, the door blocking device 1 comprises: a support 5, associable in use to a casing 2 of the electric household appliance, a striker 6 formed by a U-shaped bent metallic rod associable in use to a door 4 of the electric household appliance, from which it overhangingly protrudes towards the casing 2, and engaging means 7 for the striker 6, indicated as a whole by numeral 7, carried by the support 5 in movable manner between a first, rest or opening position, illustrated in figure 1, and a second, working or closing position, illustrated in figure 2 and 3.

In the latter position in figures 2 and 3, the engaging means 7 are adapted to engage in use, with the door 4 being closed, the striker 6 for opposing its departure from the support 5, and, conseguently, contrasting the departure of the door 4 from the casing 2 and from the respective working compartment 3 closed thereby, in the case in point constituted by the cooking chamber of a pyrolytic oven.

Finally, the device 1 comprises electromagnetic means, indicated as a whole by numeral 8, for blocking the engaging means 7 in the second, working position, and conseguently maintaining the door 4 in closing position. This is necessary when the oven, governed by a control unit 9 constituted by an electronic board (figure 3) carries out the pyrolysis function which takes the working chamber 3 to a very high temperature.

According to an aspect of the invention, the engaging means 7 consist in a bistable system comprising a fork shaped element 10 rotatably carried about an axis A by the support 5, and a spring 11 secured, eccentrically with respect to the rotation axis A of the fork shaped element 10, between the latter and the support 5, so as to stress the fork shaped element 10 to selectively assume the first and the second position by means of rotation of one towards the other, and vice versa .

According to the main aspect of the invention, in combination with this particular selection of the engaging means 7, the electromagnetic blocking means 8 comprise: a slider 12 carried by the sliding support 5 between a first position, illustrated in figure 1 and 2, and a second position, illustrated in figure 3, and arranged so that only in the latter second position the slider 12 intercepts the fork shaped element 10 for preventing the rotation thereof; a push-push mechanism 13 (figure 3) carried by the support 5 and adapted to selectively make the slider 12 assume the first and the second position; and an electromagnet 14 to selectively actuate the push-push mechanism 13.

In particular, the spring 11 is a helical spring having symmetry and actuating axis indicated by B (figure 1 and 3) secured with a first end thereof to a pin 15 parallel to axis A and arranged on the top of the support 5, and with an opposite end thereof to a pin 16 also parallel to axis A, carried in offset position with respect to axis A by the fork shaped element 10 in proximity to a peripheral edge 17 thereof, so that the actuating axis B is arranged transversally to the rotation axis A of the fork shaped element 10 and is directed so that, in the second position of the fork shaped element 10 itself, it applies in use to the door 4, by means of the striker 6 mechanically engaged by the fork shaped element 10, a stress S (figure 2), which compresses in use a peripheral seal of the door 4, known and not shown for the sake of simplicity.

For this purpose and according to the above description, the spring 11 is secured so that the actuating axis B thereof is, with respect to the plane on which the securing point of the spring 11 to the support 5, constituted in the case in point by the pin 15, and the rotation axis A of the fork shaped element 10 both lay, all arranged on a first, and selectively, on a second side of such a plane when the fork shaped element 10 is in the first and in the second position, respectively. In the case in point, when the fork shaped element 10 is in the first position (figure 1) the axis B is all over the plane containing both the pin 15 and the axis A, while when the fork shaped element 10 is in the second position (figures 2 and 3) the axis B is all under the plane containing both the pin 15 and the axis A.

In the non-limiting example shown, the door 4 turns with respect to the casing 2 about a horizontal hinge axis, not shown, parallel to axis A, therefore axis B passes respectively over and under the aforesaid plane in the first and second position of the element 10, as mentioned above. If the rotation axis is vertical instead the axis B would then simply pass either all to the right or all to the left of the indicated plane.

The fork shaped element 10 is provided with a radial recess 18 for receiving the striker 6 which interrupts the edge 17 and which, in the first position of the fork shaped element 10, faces on the opposite side of the support 5 and, in use, the door 4 of the electric household appliance and, in the second position of the fork shaped element 10, faces the support 5 and on the second side of the mentioned laying plane of rotation axis A of the fork shaped element 10 and of the pin 15, i.e. downwards.

Furthermore, the fork shaped element 10 is provided with a cantilever element 19 arranged in radially protruding manner from the same in an annular position such that, when the fork shaped element 10 passes by rotation from the first to the second position, the slider 12 may be engaged under the cantilever element 19, obviously only when the slider 12 assumes the second position thereof (figure 3), conseguently blocking all possibility of backward rotation of the fork shaped element 10 towards the first position.

In particular, the slider 12 cooperates with the radial cantilever element 19 of the fork shaped element 10 by means of an inclined plane 20 defined by a tooth element 21 of the slider 12 facing towards the fork shaped element 10, so that when the slider 12 and the fork shaped element 10 are in the respective second positions thereof, the cursor 12, moving forwards in direction of the arrow F (figure 3) applies a tangential stress T to the fork shaped element 10 which stress, in use, pushes the door 4, through the striker 6, towards a peripheral seal of the door 4 (known and not shown) similarly to what occurs by effect of the traction exerted by the spring 11 along axis B. In such reciprocal position of the slider 12 and of the fork shaped element 10 the door 4 is closed and blocked.

Thus, with the door 4 closed and blocked, the pressure that it exerts on the aforesaid peripheral seal is maximum, because the stress applied by the spring 11 is added to that applied by the slider 12. In order to ensure the correct positioning of the fork shaped element 10, the support 5 has an abutting element 22 shaped as an inclined surface for the fork shaped element 10 adapted to cooperate with the latter when it is arranged in the second position thereof (figures 2 and 3 ) .

Finally, the door blocking device 1 according to the invention includes a safety door lock device 23 carried by the support 5 in a position facing the slider 12 and comprising a latch 24 mobile between a retracted position in a seat 25 of the safety door lock device 23 and an extracted position from the seat 25 (not shown for the sake of simplicity) , wherein it is adapted to intercept the slider 12 when it is in the second position thereof (figure 3) to block it in the same position; and electric actuating means 26 (figure 3) for the latch 24.

In the illustrated example, the electric actuator means 26 for the latch 24 comprise at least one PTC pill 27 connectable in use, along with the electromagnet 14, to the control unit 9 of the electric household appliance, and a bimetal foil 28, which carries the latch 24 to extracted position when heated by the pill 27; in the latter position, in the illustrated example, the latch 24 interferes with an abutting portion 29 of the slider 12, preventing the same, when it is found in the second position, to return to the first position thereof, thus maintaining the door 4 blocked at least until the pill 27 is powered.

The operation of the device 1 is apparent from the description. The fork shaped element 10 is normally, with the door being open 4, in the position in figure 1 (first working position), in which the compartment 18 faces the door 4, arranged obliquely with respect to the striker 6; when the door 4 is taken to the closing position (figure 2) to seal the working chamber or compartment 3, the striker 6 is inserted in the compartment 18 and, due to its reciprocal oblique position, exerts on the fork shaped element 10 a push, directed parallel to the push S, which translates into a torque applied to the element 10, which turns it about the axis A, starting from the position in figure 1 towards the position in figure 2 (second working position) .

The rotation starts because the torque applied exceeds the traction exerted by the spring 11 which, being over the axis A, tends to prevent the rotation of the element 10 towards the second position. However, during such a rotation, the relative position of the axis B with respect to axis A changes progressively because the pin 15 remains still, while pin 16 turns with the element 10 approaching the support 5 and makes axis B cross axis A, and then to be arranged under the plane passing through axis A and through the pin 15. At this point, the spring 11, which has reached the maximum elongation, starts the elastic recall, and thus applies along axis B a traction which, at this point, tends to rotate the element 10 towards the second position and once this reaches it, to maintaining it. At this point the door 4 is closed, because the striker 6 cannot abandon the engagement with the compartment 18, and is pressed against the casing 2 by the spring 111, thus obtaining optimal tightness.

The door 4 may still be opened, in all cases, simply by pulling it in direction opposite to the thrust S, which makes the fork shaped element 10 turn backwards against the action of the spring 11 towards the first position of the same, in which the striker 6 is free to exit from the compartment 18.

In the second position of the fork shaped element 10, however, the door 4 may be blocked so as to prevent the opening also as a conseguence of a traction exerted on the same by a user. It is sufficient for the purpose that the control unit 9 electrically supplies the electromagnet 14, e.g. providing to the same a single voltage pulse, so that this actuates the push-push mechanism 13, of known type, which takes the slider 12 from the first working position thereof in figure 2, to the second working position in figure 3; the movement of the slider 12 directed according to the arrow F inserts it under the cantilever element 19, thus blocking any possibility of clockwise rotation of the element 10 towards the first position in figure 1; furthermore by virtue of the inclined plane 20, the thrust S exerted on the door 4 is increased. To release the door 4 it is necessary to actuate the electromagnet 14 again, e.g. by means of double pulse, in turn returning the slider 12, by means of the push-push mechanism 13, to the starting position .

For greater safety, above all in the case in which the control unit 9 cannot actuate the electromagnet 14 with differentiated pulses, the absolute safety of blocking the door 4 is provided by the auxiliary device 23; until the control unit 9 powers it electrically, it maintains the latch 24 in extracted position, blocking the slider 12 in the second working position, therefore the push-push mechanism 13 is not longer capable of returning it to the first position, not even if the electromagnet 14 is actuated, e.g. as a conseguence of a spurious pulse emitted by the control unit 9.

Claims

1. A blocking device (1) for the door of an electric household appliance comprising a support (5), associable in use to a casing of the electric household appliance, a striker (6) associable in use to a door of the electric household appliance, engaging means (7) for the striker carried by the support movable between a first and a second position, in the latter the engaging means being adapted to engage in use the striker, with the door being closed, for opposing its departure from the support, and electromagnetic means (8) for blocking the engaging means in the second position; characterized in that, in combination:

- the engaging means (7) consist of a bistable system, comprising a fork shaped element (10) rotatably carried about an axis (A) by the support, and a spring (11) eccentrically secured with respect to the rotation axis (A) of the fork shaped element, between the latter and the support (5), so as to stress the fork shaped element (10) to selectively take the first and second positions by rotating from one to the other, and vice versa; and

- the electromagnetic blocking means (8) comprise: a slider (12) carried in sliding manner by the support between a first and a second position, only in the latter the slider intercepting the fork shaped element (10) for preventing the rotation thereof; a push-push mechanism (13) carried by the support and adapted to selectively make the slider to take the first and second position; and an electromagnetic actuator (14) to selectively actuate the push-push mechanism (13).

2. A door blocking device according to claim 1, characterized in that the spring (11) is a helical spring secured so that an actuating axis (B) thereof is arranged transversally to the rotation axis (A) of the fork shaped element (10) and directed so that, in the second position of the fork shaped element itself, it applies in use a stress (S) to the door, by means of said striker, which stress causes a peripheral seal of the door to be compressed.

3. A door blocking device according to claim 1 or 2, characterized in that said spring (11) is secured so that an actuating axis (B) thereof, with respect to a plane on which both the rotation axis (A) of the fork shaped element and the securing point (15) of said spring to the support (5) are laying, is completely arranged on the first side or on the second side of said plane, selectively, when the fork shaped element (10) is in the first and the second position, respectively.

4. A door blocking device according to claim 3, characterized in that said fork shaped element (10) is provided with a radial recess (18) for receiving the striker, said recess facing the opposite side of the support and, in use, facing the door of the electric household appliance in said first position of the fork shape element, and facing towards the support and on the side of the second side of the laying plane of the rotation axis of the fork shaped element in the second position of the fork shaped element itself.

5. A door blocking device according to one of the preceding claims, characterized in that said fork shaped element (10) is provided with a cantilever element (19) arranged radially protruding therefrom at an angular position such that, when the fork shaped element passes from the first position to the second position by means of a rotation, the slider (12) may be engaged below said cantilever element (19) when the slider also takes said second position, thus blocking all backward rotation possibilities of the fork shaped element (10) towards the first position.

6. A door blocking device according to claim 5, characterized in that said slider (12) cooperates with said radial cantilever element (19) of the fork shaped element through an inclined plane (20), so that, when both the slider and the fork shaped element are in the respective said second position, the slider applies a tangential stress (T) to the fork shaped element, which stress pushes in use the door towards a peripheral seal of the door by means of said striker.

7. A door blocking device according to one of claims 5 and 6, characterized in that it includes a safety door lock device (23) carried by the support (5) in a position facing said slider and comprising a latch (24) movable between a retracted position in a seat (25) of the safety door lock device and an extracted position from the seat, and wherein it is adapted to intercept the slider (12) when it is in said second position to block it therein; and electric actuating means (27) for the latch.

8. A door blocking device according to claim 7, characterized in that said electric actuating means for the latch comprise a least one PTC pill (27) connectable in use, along with said electromagnet (14), to a computing unit (9) of the electric household appliance.

9. A door blocking device according to one of the preceding claims, characterized in that said support (5) includes an abutting (29) element shaped as an inclined- plane for said fork shaped element (10) adapted to cooperate with the latter when it is arranged in said second position.