EP2175200A1

EP2175200A1 - Door locking device specifically for a pyrolytic oven

Info

Publication number: EP2175200A1
Application number: EP08425660A
Authority: EP
Inventors: Onofrio Rocchitelli
Original assignee: Elettrotecnica Rold SRL
Current assignee: Elettrotecnica Rold SRL
Priority date: 2008-10-10
Filing date: 2008-10-10
Publication date: 2010-04-14

Abstract

The present invention relates to a door locking device for household electrical appliances.
In particular, the door locking device according to the present invention is suitable to be used as a safety device on an oven, and more particularly on an oven provided with a pyrolysis function.
The device according to the present invention is characterised in that it includes first safety means adapted to prevent the door locking latch from being coupled and the pyrolysis function from being started when the door is open.

Description

The present invention relates to a so-called door locking device, specifically for an oven.
As known, many household electrical appliances are provided with devices which prevent the door or shutter from accidentally opening under certain conditions.
In particular, in the case of ovens provided with a self-cleaning function, also known as pyrolysis, it is extremely important that such a device will be present.
Indeed, it is known how certain ovens currently marketed are provided with a function that allows the self-cleaning of the oven cavity by the combustion of the organic residues therein. To achieve this result, the temperature inside the oven reaches about 400° C, and is maintained for a variable time of up to 90 minutes.
During the self-cleaning operation, the temperature inside the oven is therefore very high, which makes the operation itself very dangerous should the door of the oven be accidentally opened by the user.
This potentially dangerous condition imposes on manufacturers the need to guarantee an adequate level of safety by equipping the oven with a door locking device.
Devices serving the door lock function are currently known, but they have an insufficient or in any case improvable level of safety.
The main task of the present invention is therefore to provide a door locking device, specifically for pyrolytic ovens, but not only, with improved effectiveness from the point of view of safety.
In particular, as part of this task, the object of the present invention is to provide a door locking device that is able to effectively satisfy a plurality of required functional and safety specifications of the component.
A further object of the present invention is to provide a door locking device whose safety functions include the presence of an electronic and mechanical redundancy of the control device.
Even more specifically, the object of the present invention is to provide a door locking device that also includes a "door open" safety function against the start of the pyrolysis function when the oven door is open, a "door opening during the locking step" safety function that prevents the pyrolysis function from starting in the case of the voluntary opening of the oven after the door locking latch begins to close but before the latch engages, a "self-repair" function, and a "reset" function.
This task and these and other objects, which will become more apparent from the following disclosure of a preferred embodiment of the invention, are achieved by an automatic door locking device characterised in that it includes a plurality of safety means.
Other features and advantages of the invention will become more apparent from the following detailed description, given by way of non-limitative example and illustrated in the accompanying drawings, in which:

figure 1 shows a perspective view of the device assembly according to the present invention in the opening position;
figure 2 shows the same view as figure 1, but with the device in the door locked position;
figures from 3 to 6 shows views of details of the device according to the present invention.

According to a preferred embodiment of the invention illustrated in the abovementioned figures by way of non-limitative example, the device 1 includes a basic structure 1a which is adapted to be integrally joined to the household electrical appliance, in particular to an oven, and properly shaped so as to contain a plurality of micro-switches A, B, C and D. With particular reference to figures 1 and 2, such micro-switches are placed near the outside edge of the basic device structure 1a, so that the other components illustrated below are accommodated close to the centre of said basic structure 1a.
The device according to the present invention includes first safety means to prevent the pyrolysis function from being activated while the oven door is not closed.
Said first safety means specifically include a door closing lever 20, which may translate with respect to said basic structure 1a and is adapted to abut, with one end 21 thereof, against an appropriate backing plate 70a provided on the door of the oven 70 when such a door is gradually closed. Closing the oven door firstly causes the end 21 of the lever to abut against the backing plate 70a, followed by the translation of the lever 20 itself, which is pushed by the backing plate 70a.
By comparing figure 1 with figure 2, it is apparent how, when the oven door is closed, the closing lever 20 is pushed towards the interior of said device 1.
Elastic means act between the lever 20 and the basic structure 1a of said device. In particular, a helical spring is provided, which is positioned inside the cavity 24a and adapted to act between a first backing plate on said lever 20 and a second backing plate on said basic structure 1a, so that such a spring opposes the translation of said lever caused by closing the door. In addition, in order to ensure the required reliability, a second spring is accommodated in the cavity 24b, as seen in figure 1, which is substantially identical to the first. The second elastic spring serves the same function as the first.
The bias of the springs tends therefore to return the door closing lever 20 to the position shown in figure 1 corresponding to the situation in which the door of the household electrical appliance is open.
When the oven door is closed and the lever 20 is pushed to the 'returned' position corresponding to the door closed situation, said lever activates the micro-switch A, thereby providing the oven control electronics with the information that the door is closed.
Said first safety means for preventing the oven door from opening when the pyrolysis function has been initiated, also including a lever-holder wheel 40, rotationally connected to said basic structure 1a, and a switch activation lever 30, connected in turn to said lever-holder wheel 40.
As can be seen from figures 5 and 6, the lever-holder wheel 40 and the activation lever 30 are connected to each other. In particular, the lever-holder wheel 40 to which the door lever or closing latch 50 is connected, has a central portion 44 adapted to support said switch activation lever 30, as can be clearly seen in figure 4.
The activation lever 30 has a radial extension 30a at one end thereof, in which a guide 34 is cut with a substantially curved shape.
The connection between the lever-holder wheel 40 and the activation lever 30 is achieved also by means of a pin 43 which is adapted to slide within said guide 34 cut into said switch activation lever 30. The guide or slot 34 has a curved profile, so that the relative rotation of the lever-holder wheel 40 with respect to the activation lever 30 about the same rotation axis I which is substantially perpendicular to the surface of said basic structure 1a is guided by sliding the pin 43 into the guide 34. In addition, again with reference to figures 5 and 6, an elastic element 60, which in the embodiment shown in the figures consists of a helical spring accommodated in a seat provided for the purpose, acts between said switch activation lever 30 and said lever-holder wheel 40 so as to oppose relative rotations in opposite directions of the two elements.
As can be seen from figures 1 and 2, an electric motor 90, advantageously of the synchronous type, is connected to said switch activation lever 30 by means of the appropriately shaped central slot 32.
Naturally, the device according to the present invention may also be driven by other means suitable for the purpose according to the known state of the art. For example, according to an alternative embodiment of the device according to the present invention, the synchronous electric motor may be replaced with a solenoid.
The electric motor 90 is therefore adapted to rotate the switch activation lever 30 about the axis A. By means of the pin 43 and the guide 34, the switch activation lever 30 then rotates the lever-holder wheel 40.
The electric motor 90 may naturally be replaced by other mechanisms having the same function of moving the device, but without departing from the scope of the present invention.
At the end of the radial extension 30a of the activation lever 30, there is a drive pin 31, substantially cylindrical shaped, which extends perpendicularly from said radial extension 30a towards the surface of said basic structure 1a.
Said drive pin 31 is adapted to be inserted into a guide slot 81 specifically made in a slide 80 adapted to slide on the surface of said basic structure 1a. The slide 80 is able to translate due to the rotation of the activation lever 30. As described, the drive pin 31 is inserted indeed into a guide 81 made on said slide 80 and has a substantially curved profile, so that the rotation of the activation lever 30 corresponds to the translation of the slide 80.
The slide 80 has a profile specifically shaped to come into contact with and activate in turn one or more micro-switches, in particular the slide 80 is adapted to come into contact with and activate the micro-switch B, which signals the position of the closing latch 50 in the door locking position.
At the same time, as can be seen from the detail in figure 3, the drive pin 31 also serves a mechanical safety function relative to the activation of the door locking device when the oven door is open. Such a mechanical safety function is obtained due to the particular conformation of the door closing lever 20. When the door closing lever 20 is in the position illustrated in figure 3, corresponding to the oven door open condition, with the device being assembled, the relative position of the various elements is such that said drive pin 31, integral with the activation lever 30, abuts against a first backing plate 22a obtained at the end of said door closing lever 20. In this manner, when the oven door is open and the lever 20 is in the door open position in which it is biased and held by the helical spring, not shown in the figures, acting between the lever 20 itself and the basic structure 1a, the backing plate 22a houses the drive pin 31 thus preventing the rotation of the activation lever 30, and of the lever-holder wheel 40 therewith.
In this manner, in addition to the presence of the micro-switches that dialogue with the device control electronics, there is a mechanical safety redundancy that prevents the device from being activated, i.e. locking of the door caused by the rotation of the closing latch.
The device according to the present invention also includes second safety means adapted to prevent the pyrolysis function from starting when the door 70 is opened during the activation of the device, thus achieving the "door open during the locking step" function.
With particular reference to figure 4, said door closing lever 20 has a second backing plate 23 along its length, which is adapted to house a projection 41a extending in a substantially vertical direction from a radial expansion 41 specifically provided on said lever-holder wheel 40. The view in figure 4 illustrates the situation in which the door closing lever 20 is in the position corresponding to the door open, while the device has started to work and the door closing latch is moving towards the stroke end position. The backing plate 23 in this case strikes the projection 41a preventing the lever-holder wheel 40 from performing the entire rotation and activating the stroke end micro-switch C by means of its profile. Such a situation may only occur in the event of a voluntary opening of the door once the device has been previously activated and has started to work. In the case, after activating the relative function using the oven controls, and therefore after the door locking device has started to work and begun rotating the latch 50 to bring the latter to the door locked condition, the user decides to open the door again, the backing plate 23 placed on the lever 20 prevents the lever-holder wheel 40 from completing its rotation and activating the stroke end micro-switch C. This achieves the safety function related to the door opening during the locking step.
As specifically shown in figures 1 and 2, when the latch 50 is closed by the action of the electric motor, the latch engages the backing plate 70a integral with the oven door 70, in particular by means of its end 51 in the shape of a hook.
The end of the lever or latch 50 has an internal profile at the end 51 which is substantially perpendicular to the longitudinal extension of the lever 50, while the surface facing the oven door is shaped so that the initial portion 52 has an inclined plane.
The presence of this inclined surface 52 allows the device to have a self-repair function. In the event that the user forcefully closes the oven door when the latch 50 is already in the closing position, obviously having bypassed the electronics and the other safety systems to create the possibility that such an event could occur, the presence of the inclined plane 52 allows the force acting on the lever to be converted into a radial component with respect to the lever-holder wheel 40 to which the lever 50 is connected. This radial component causes a rotation of the lever 50 itself that allows the lever to lift over the backing plate 70a. In virtue of the presence of the elastic spring 60 acting between the lever-holder wheel 40 and the activation lever 30, the forceful closure of the oven door when the device 1 is in the door locked configuration overcomes the resistance of the spring and causes the movement of the lever or latch 50, and the subsequent repositioning of the end 51 of the latch cooperating with the interior of the backing plate 70a due to the bias of the spring 60. The presence of the spring 60 and the fact that the lever-holder wheel 40 may rotate with respect to the activation lever 30 until the pin 43 reaches the stroke end position of the slot 34 guarantee the self repair function consisting in the possibility of moving the lever 50 and thereby rotating the lever-holder wheel 40 without damaging the motor 90, because the movement of the lever and thus of the lever-holder wheel 40 is not transmitted to the activation lever 30 and to the motor 90.
A further additional function of the device according to the present invention is the reset function. In the event that the user opens the oven door while the device 1 is returning the door locking latch 50 to the opening position shown in figure 1, the door closing lever 20 is biased by the spring acting between said lever 20 and said basic structure 1a to be placed in the door open position, which should nevertheless correspond to a position of the lever-holder wheel 40 corresponding to the opening position shown in figure 1.
The presence of the chute or inclined plane 22b at the end 22 of the door closing lever 20, on the end side opposite to the backing plate 22a, allows the drive pin 31 integral with the activation lever 30 to slip along such an inclined plane overcoming the resistance of the spring, not shown, inserted in the housing 24 and acting between said lever 20 and said basic structure 1a, moving the door closing lever 20 which translates until the drive pin 31 reaches its seat again, close to 22a, thus returning to the correct starting configuration of door open.
It is worth noting how the lever or latch 50 is preferably made of metal material, while all the other parts and components of the device may be made of plastic material.
The door locking device 1 according to the present invention operates as follows.
In the situation shown in figure 1, the oven door is open and therefore the oven electronics prevent the pyrolysis function from starting due to the fact that the door closing lever 20 detects the door open condition and does not close the contact on the micro-switch A.
When the door 70 is manually closed by the user, the lever 20 is pushed towards the inside of the device, into the door closed position shown in figure 2, and the micro-switch A is activated. At this point, the oven control electronics receive the signal that the door is closed and may start closing the door locking device. The motor 90 is then activated by closing the lever or latch 50. Since the lever 20 is in a position corresponding to the door closed condition, the backing plate 22a does not hold the drive pin 31 and the rotation neither of the lever-holder wheel 40 nor of the activation lever 30 that integrally rotates with the lever-holder wheel 40 because of the pin 43 striking the guide 34.
The electric motor then moves the latch 50 to the door locked position, with the end 51 of the latch cooperating with the backing plate 70a as shown in figure 2.
During the rotation of the lever-holder wheel 40 and the activation lever 30, the drive pin 31 integral with said activation lever 30 rotates and moves along the guide 81 provided on the slide 80. Because of the curved profile of the guide 81, the slide 80 translates and activates the auxiliary micro-switch B and the auxiliary micro-switch D, which serve the same function. By continuing in its rotation, the lever-holder wheel 40 comes against the contact of the stroke end micro-switch C, which sends the signal to stop the electric motor to the oven control electronics, thus stopping the device in the door locked position, with the auxiliary micro-switch B and door closed micro-switch A closed, which for the control electronics means a condition in which it is possible to start the pyrolysis function.
When pyrolysis has finished, the oven control electronics activate the motor 90 again, thus causing the opening of the door lock 50, and the user can normally open the oven.
In addition to the basic operation, as mentioned, the door locking device according to the present invention has a multiplicity of safety functions.
In the situation illustrated in figure 1, the oven door 70 is open and thus there is no contact between the backing plate 70a on the inner wall of the oven door and the door closing lever 20.
In this door open condition, the door closing lever 20 is thus kept in the position shown in figure 1, corresponding to the door open condition, by the presence of the elastic spring, not depicted in the figures, which acts between said lever 20 and the basic structure 20.
In this condition, the micro-switch A which is activated by the door closing lever 20 when the lever translates by closing the door and thus by means of the thrust applied to the lever by the backing plate 70a against the end 21 of the lever 20, is not activated, whereby it does not send the door closed signal to the oven control electronics, and the pyrolysis function may not be started.
In addition to this safety feature relating to the start-up with the door open connected to the control by the micro-switch A, the device according to the present invention has a second, mechanical-type safety control consisting of the described backing plate 22a specifically provided on the lever 20 and adapted to prevent, by holding the drive pin 31, the rotation of the activation lever 30 and, subsequently, of the lever-holder wheel 40, which is held by the pin 43 striking against the wall of the guide 34.
The device 1 according to the present invention therefore has a mechanical redundancy on the safety device which prevents the door lock from being activated, and therefore the pyrolysis function, when this is selected with the oven door open.
Furthermore, according to the above shown, another important safety function is achieved by the device according to the present invention. Such a safety function consists in opening the door by the user, once the pyrolysis function has been selected on the oven electronics, but before the latch 50 locks the door 70.
At this step, as mentioned, the door closing lever 20 will be in a position corresponding to the door open condition, and the backing plate 23 on the lever 20 prevents the further rotation of the lever-holder wheel 40 by striking against the projection 41a and thus preventing the lever-holder wheel 40 from activating the stroke end micro-switch C, by continuing the rotation imposed by the motor 90.
On this type of safety control, there is also a mechanical redundancy on the control. Indeed, there is the simultaneous position of the lever 20 in a position corresponding to the door open condition, which translates as non-activation of the micro-switch A, and moreover there is the mechanical impediment, by means of the backing plate 23, to the movement of the lever-holder wheel 40, which translates as non-activation of the stroke end micro-switch C, which also prevents the pyrolysis function from being activated.
As mentioned, the device according to the present invention is also provided with a self-repair function in the event of the forceful closure of the door by the user, even if the door locking lever 50 is in the closed position.
Furthermore, the reset function has also been illustrated, which makes it possible to return the device to its initial, correct configuration even in the event that the user forcibly opens the door during rotation of the door lock lever 50.
It has thus been shown how the door locking device according to the present invention achieves the prefixed task and aims.
In particular, the door locking device according to the present invention is particularly effective from the point of view of safety.
An object achieved by the present invention is to provide a door locking device which has both mechanical and electrical-type safety means.
A further object achieved by the present invention is to provide a door locking device that includes a plurality of safety functions, while remaining an extremely compact and reliable device.
In particular, it has been shown how an object achieved by the device according to the present invention is to provide the "door open" safety function, the "door opening during the locking step" function, a "self-repair" function and a "reset" function in a single device.
In addition, the door locking device according to the present invention is extremely compact and simple to be constructed, despite incorporating a plurality of functions.
Several changes may be made by the person skilled in the art without departing from the scope of protection of the present invention.
Therefore, the scope of protection of the claims must not be limited by the illustrations or the preferred embodiments shown in the description by way of example, but rather the claims must include all patentable novelty features deducible from the present invention, including all the characteristics that would be treated as equivalent by the person skilled in art.

Claims

A door locking device (1) for household electrical appliances, specifically for ovens provided with a pyrolysis function, of the type including a basic structure (1a) adapted to be be integrally joined to the electrical appliance and properly shaped so as to contain a plurality of micro-switches (A, B, C), a door locking latch (50) adapted to be moved between a door opening position and a door locked position in which it firmly holds the door (70) of said household electric appliance in the closing position, said device (1) being characterised in that it includes first safety means adapted to prevent said door locking latch (50) from being coupled and the pyrolysis function from being started when the door (70) is open.
A door locking device (1) according to the preceding claim, characterised in that it further includes second safety means adapted to prevent the pyrolysis function from starting when the door (70) is opened during the activation of the device (1) and before the door locking latch (50) locks the door.
A door locking device (1) according to one or more of the preceding claims, characterised in that said first safety means include a door closing lever (20) slidingly associated with said basic structure (1a), elastic means being placed between said lever (20) and said basic structure (1a), and adapted to activate a first door closing micro-switch (A) when the door (70) is closed, and at least one lever-holder wheel (40) rotationally connected to said basic structure (1a) and to which said door locking latch (50) is connected, and a switch activation lever (30), connected in turn to said lever-holder wheel (40).
A door locking device (1) according to the preceding claim, characterised in that said first safety means further include at least one drive pin (31) integral with said activation lever (30) and adapted to slide into a curved guide (81) specially provided on a slide (80) slidingly associated with said basic structure (1a), said drive pin (31) being adapted to strike against a backing plate (22a) specifically provided on said door closing lever (20) when said lever (20) is in the position corresponding to the door (70) open condition.
A door locking device (1) according to the preceding claim, characterised in that said slide (80) may translate with respect to the basic structure (1a) due to the sliding of said drive pin (31), which defines a circular trajectory because of the rotation of the activation lever (30), along said curved guide (81), and may activate one or more micro-switches (B) during its translating movement.
A door locking device (1) according to anyone of the claims from 2 to 4, characterised in that said second safety means include a backing plate (23) specifically provided on said door closing lever (20) which is adapted to house a projection (41a) extending in a substantially vertical direction from a radial expansion (41) specifically provided on said lever-holder wheel (40), when said door closing lever (23) is in a position corresponding to the situation in which the door (70) is open, such that said backing plate (23) prevents said lever-holder wheel (40) to which said door locking latch (50) is connected from rotating, in the case of the door (70) being opened while the device is moving towards the closing position.
A door locking device (1) according to one or more of the preceding claims, characterised in that said lever-holder wheel (40) has a central portion (44) adapted to support said switch activation lever (30), said lever-holder wheel (40) being equipped with a pin (43) which is adapted to slide within a substantially curved guide (34), so that the relative rotation of said lever-holder wheel (40) with respect to said activation lever (30) about the same rotation axis (I) is guided by sliding said pin (43) in said guide (34).
A door locking device (1) according to one or more of the preceding claims, characterised in that the relative rotation of said lever-holder wheel (40) with respect to said switch activation lever (30) is blocked in one direction by stroke end of the pin (43) striking against the end of the guide (34) and in the other direction by the presence of an elastic element (60) that opposes such a rotation.
A door locking device (1) according to the preceding claim, characterised in that it further includes an elastic element (60) acting between said switch activation lever (30) and said lever-holder wheel (40) so as to oppose relative rotations in opposite directions of said two elements (30, 40).
A door locking device (1) according to one or more of the preceding claims, characterised in that said door locking latch (50) has an inclined surface (52) at the end thereof facing said door (70) of the household electric appliance, which surface is adapted to convert the force acting on said door locking latch (50), when the door is closed, into a radial component with respect to the lever-holder wheel (40) on which said door locking latch (50) is mounted, so as to allow the door locking latch (50) to return to the correct operating position without being damaged, even in the case that the door (70) is closed by the user when said door locking latch (50) is in the closing position.
A door locking device (1) according to one or more of the preceding claims, characterised in that it further includes elastic means acting between said lever (20) and said basic structure (1a), preferably a helical spring, adapted to return said door closing lever (20) to the position corresponding to the door open condition, in which the door closing micro-switch A is not activated.
A door locking device (1) according to one or more of the preceding claims, characterised in that it includes an electric motor (90).
A door locking device (1) according to one or more of the claims from 1 to 11, characterised in that it includes a solenoid.