EP1102519B1 - Fast locking device,particularly for microwave oven door - Google Patents

Description

The present invention relates to a device for rapidly locking a first part on a second part with respect to which the first part is in motion, in particular for a microwave oven door, and more particularly such a device comprising
a locking unit with two stable stop positions, and
first actuating means for bringing the closure unit from its first stable position to its second stable position when the first piece is brought from an open position relative to the second piece to a closed position with respect to the second piece and to return the closure unit from its second stable position to its first stable position when the first piece is brought from its closed position relative to the second piece to an open position relative to the second piece.

We already know closure assemblies including such elements, used for example in microwave ovens.

In these ovens, the first piece is constituted by the door oven and the second piece by the structure of this oven. The unit of closure is mounted on the oven structure and oscillates from one to the other of its stop positions stable under the action of a finger actuation integral with the door. This finger constitutes both the first actuating means, and a door locking means by its cooperation with the closing unit when the door is in closed position.

When the door is closed manually, the finger actuation causes the closing unit in its second stable position, and this unit in turn holds the door in position closed because of the stability of this position. When the door is then opened, whether manually or under the action of a means of maneuver, the finger tilts the closing unit beyond a position of unstable equilibrium, tilting that continues of itself to the first stable stop position. The unit of closure then remains in this position until closing next door.

The main drawback of such an arrangement lies in the fact that it does not provide a door lock but a simple locking in the closed position. We can not exclude all risks leakage of electromagnetic waves.

The present invention aims to overcome this disadvantage.

Document US Pat. No. 5,300,745 discloses a device for placing an oven at microwave in a stopping position. For this purpose, a locking finger is provided preventing, when the oven door is open, the rotation of a wheel which prevents starting the oven.

More particularly, the invention aims to provide a quick locking device from one part to another, and especially a microwave oven door on the structure of this oven.

The invention also aims to prevent any leakage of waves a microwave oven for the duration of its operation.

The invention also aims to ensure the locking from one room to another with low electricity consumption, in a silent way, and without heating up.

For this purpose, the subject of the invention is a locking device according to claim 1.

The device according to the invention thus ensures not only a blocking of the first piece on the second, in particular of the door of a microwave oven in a closed position on the structure of this oven, using the bistable closure unit, but also a lock in this position. This lock is done by through the closure unit including the first organ of interlocking with the second locking member of the locking unit when the latter is brought into position locked by the second actuation means activated by their control means.

In a particular embodiment, the second actuating means comprise a current electric motor continuous and transmission means to transmit the movement of the motor shaft to the second locking member.

It will be observed that it is already known to use electromagnets for locking microwave ovens. In this case, a plungeur is used as a bolt that engages in an orifice corresponding in the oven door.

Such electromagnet devices, however, are not satisfactory.

They are in the first place slow to engage, typically the order of several seconds. Such a delay is often unacceptable, if we take into account that a microwave oven is often not used only in durations of a few tens of seconds.

Moreover, it is of course necessary to maintain electromagnet supplied for the duration of the use of the oven, since only this electromagnet keeps the door closed. But, besides the fact that this power consumes electrical energy not negligible, it leads to a relatively important and, above all, a high noise level.

On the contrary, a DC electric motor associated with a suitable gearbox can provide a significant torque that is transmitted to the closing unit, preventing it from leaving his second stable position. This important couple is furthermore obtained without overheating and quietly, even with a high power current, of the order for example of 1 ampere under a voltage of 12 volts. Finally, a DC motor can be powered directly by a microprocessor.

The second actuating means can further include elastic return means

Also in a particular embodiment, the device according to the invention comprises a seal between the first piece and the second piece, the first and second locking members being arranged to tend to drive the unit closing away from its first stable position from its second stable position when the second locking member is in the locking position, so as to compress the seal when the first piece and the second piece are in closed position.

In this embodiment, the security of use is better ensured by the presence of the seal. It is compressed by the action of the second locking member. all wave leakage is thus prevented.

Also in a particular embodiment, the unit of closure includes a fork mounted to rotate on one of the parts, elastic means being provided for pressing said fork in either direction of rotation away from a position unstable balance.

More particularly, the first actuating means may include an actuating finger mounted on one of the parts and arranged to cooperate with an element of the unit of closing mounted movably on the other piece between two positions of Stable abutments.

Even more particularly, the actuating finger can be arranged to engage between the branches of the fork and push a first branch of the fork when the first piece is brought from an open position with respect to the second piece to its closed position relative to the second piece, and to pull a second branch of the fork when the first piece is brought from its closed position relative to the second piece to a open position with respect to the second piece.

The second branch of the fork can be arranged to be in abutment on the actuating finger when the closure unit is in its second stable position.

In a particular embodiment, the locking unit comprises a first contact surface arranged to come to contact of a second contact surface of the closure unit when the closing unit is in its second stable position and that the second locking member is in the position of locking.

More particularly, the second contact surface can be arranged on a third branch of the fork.

The invention also relates to a microwave oven characterized in that it comprises a locking device such as described above.

More particularly, the microwave oven according to the invention may include a microwave tube, control means which can be arranged to bring the second locking in its locking position when the microwave tube is activated.

Thus, the oven according to the invention is automatically locked when it is turned on.

More particularly, the control means can be arranged to maintain an electric current in the motor DC power as long as the microwave tube is activated.

The door of the microwave oven according to the invention is thus kept locked during the entire period of operation of the oven.

Another subject of the present invention is a method for rapidly locking a first part on a second part with respect to which the first part is in motion, in particular for a microwave oven door, using a device comprising
a locking unit with two stable stop positions,
a locking unit, and
first actuating means for bringing the closure unit from its first stable position to its second stable position when the first piece is brought from an open position relative to the second piece to a closed position with respect to the second piece and to return the closure unit from its second stable position to its first stable position when the first piece is brought from its closed position relative to the second piece to an open position relative to the second piece,
characterized by the fact that it comprises
a step of moving a locking member movably mounted on the locking unit, from an open position where the first piece is free to move, to a locking position in which said locking member and a other locking member on the closure unit cooperate to maintain the closure unit in its second stable position when the first part is in the closed position relative to the second part.

More particularly, the subject of the invention is a method for locking the door of a microwave oven on the structure of this oven, which oven comprises a microwave tube and a gasket between the door and the structure, this method being able to further include a step of maintaining the second locking member applied against the first member of locked for the duration of the microwave tube is activated, so as to compress the seal during all this duration.

In this process, in order to maintain the second locking member applied against the first member of locking, maintain an electric current in a motor to direct current arranged to move the second body of locking its open position to its locking position.

• la figure 1 représente un dispositif selon l'invention appliqué à un four à micro-ondes avec la porte du four ouverte ;
• la figure 2 est une vue similaire à la figure 1 avec la porte du four en cours de fermeture ;
• la figure 3 est une vue similaire à la figure 1 avec la porte du four fermée, avant verrouillage ;
• la figure 4 est une vue similaire à la figure 1 avec la porte du four fermée, après verrouillage ;
• la figure 5 illustre schématiquement la commande du dispositif selon l'invention ; et
• la figure 6 est un graphique illustrant en fonction du temps (en millisecondes), le courant (en ampères) dans le moteur à courant continu lors d'une phase de fermeture de la porte du four.

A particular embodiment of the invention will now be described, by way of nonlimiting example, with reference to the appended diagrammatic drawings in which:

• Figure 1 shows a device according to the invention applied to a microwave oven with the open oven door;
• Figure 2 is a view similar to Figure 1 with the door of the oven being closed;
• Figure 3 is a view similar to Figure 1 with the oven door closed, before locking;
• Figure 4 is a view similar to Figure 1 with the closed oven door, after locking;
• FIG. 5 diagrammatically illustrates the control of the device according to the invention; and
• Figure 6 is a graph illustrating as a function of time (in milliseconds), the current (in amperes) in the DC motor during a closing phase of the oven door.

The door 1 of the microwave oven is shown schematically in FIG. and the structure 2 comprising the frame of this door. A seal 3 disposed on the periphery of the door 1 ensures the sealing of inside the oven with respect to the outside of the oven when the door 1 is closed.

Structure 2 essentially supports, as far as the invention, a closing unit 4 and a locking unit 5. The door 1 supports an actuating finger 6.

The closure unit 4 comprises a fork 7 and a spring Helical return 8 for this fork 7. The fork 7 is mounted rotating about an axis 9 on the structure 2, close to the door frame 1.

The fork 7 has three branches 10, 11 and 12 oriented generally in the same direction, and a lever arm 13 oriented usually in the opposite direction. The outer branch 10 of the fork 7 is the closest to the door 1 and the outer branch 12 is the furthest away. The middle branch 11 is substantially in the extension of the lever arm 13.

The return spring 8 is in compression with one of its ends bearing on the free end of the lever arm 13 and its another end bearing on a stop 14 secured to the structure 2. Ball joints are provided at both ends for allow some angular movement of the spring.

The free end of the lever arm 13 is generally disposed between the axis 9 of rotation of the fork 7 and the stop 14. Thus, the return spring 8 always tends to separate the fork 7 from a unstable equilibrium position in which the free end of the arm of lever 13, the axis 9 of rotation of the fork 7 and the stop 14 are aligned.

The rotation of the fork 7 about the axis 9 is limited, in the direction of the arrow F1 which generally leads the branches 10, 11 and 12 towards the door 1, by a stop 15 secured to the structure 2. On will see below that, in the other direction, that of the arrow F2, this rotation is limited by the cooperation of the finger 6 with the face 16 inside the branch 10 of the fork.

The locking unit 5 comprises an electric motor 17 to direct current, a gear 18 meshing with the output axis 19 of the motor 17, and a pivoting lever 20 having a toothed sector 21 meshing with a pinion 22 coaxial with, and integral with, the wheel toothed 18. The motor 17, the axis of rotation 23 of the toothed wheel 18 and the pivot axis 24 of the lever 20 are mounted on the structure 2.

A return spring 25 has one of its ends fixed to the structure 2 and its other end fixed to the end of the lever 20 opposite to the toothed sector 21. This spring 25 acts here in tension and is arranged to rotate the lever in the direction of the arrow F3 and therefore to bring the end of the lever 20 opposite the sector toothed 21 away from the closing unit 4. The motor 17 is powered to pivot the lever 20 in the opposite direction to that of the arrow F3.

In the configuration of Figure 1 where the oven door is open, the fork 7 is supported on the stop 15 under the action of the spring 8. The finger 6 is then in front of the face 26 of the branch 11 which faces the branch 10 (Figure 2).

Also in this configuration, the lever 20 is retained at the distance of the fork 7 by the return spring 25. The motor Electric 17 is not excited and therefore provides no torque.

When the door 1 is brought into the closed position, as shown in FIG. 2, the finger 6 comes into contact with the face 11 of the branch 11 of the fork that faces the branch 10. The finger 6 press this face 26 and thus brings the fork 7 to rotate in the direction of arrow F2, first compressing the spring 8.

When the unstable equilibrium point is reached and then exceeded, the spring causes the rotation of the fork 7 to continue in the direction of arrow F2. The face 27 of the branch 10 of the fork 7 which facing the branch 11 then comes into contact with the finger 6 (of side of the latter opposite to the previous contact with the face 26 of the branch 11), which has the effect of completing the closing of door 1 and press it against the seal 3, as shown in figure 3.

The oven can then be started. At this moment, the control electronics 28 (FIG. 5), constituted for the most part a microprocessor, on the one hand activates the oven microwave tube (not shown), and secondly locks the door.

For this, as shown in FIG. 6, a controlled current in a first phase of 40 ms at a value of 1 A is brought to 17. During a second phase of 20 ms, the current in the motor 17 is canceled. Finally, the current is brought back to the value of 0.4 A throughout the duration of the use of the oven, during which the door remains locked.

The locking position is shown in FIG. rotation of the motor 17 under the effect of the excitation current brings the lever 20 to rotate in the opposite direction to the arrow F3. In this movement, a contact surface 29 of the end 30 in the form of lever hook 20 comes into contact with a contact surface 31 formed on the branch 12 of the fork 7 vis-à-vis the branch 11. This movement is executed against the action of the return spring 25.

In the position of FIG. 4, the contact of the surfaces 29 of the lever 20, and 31 of the fork 7, ensures a lock of the fork 7 and therefore door 1 which can not be opened as long that the motor 17 is powered. In addition, the seal 3 is compressed, preventing any leakage of waves.

At the end of the oven use, the microwave tube stops to be powered, as well as the engine 17. In these circumstances, the return spring 25 causes a pivoting of the lever in the direction of the arrow F3 and consequently the release of the fork 7.

When the door is pulled for opening, the finger 6 press on the face 27 of the branch 10 of the fork 7, and thus This fork pivots in the direction of the arrow F1. When the unstable equilibrium point is reached and then exceeded, the spring 8 causes the movement of the fork 7 to continue until contact with the stop 15. The whole is then found in the configuration of Figure 1.

The invention thus ensures a positive locking of the door of the oven. This locking is accompanied by a compression of a joint Peripheral sealing at the door, and lasts as long as the use of the oven.

Claims (16)

1. A device for the rapid locking of a first piece (1) on a second piece (2) with respect to which the first piece is in movement, in particular for a microwave oven door, the said device being intended to be tripped when the microwave oven is started, comprising

   a closure unit (7) with two stable stop positions, and

   first actuation means (6) for bringing the closure unit (4) from its first stable position to its second stable position when the first piece (1) is brought from an open position with respect to the second piece (2) to a closed position with respect to the second piece, and to return the closure unit (4) from its second stable position to its first stable position when the first piece (1) is brought from its closed position with respect to the second piece (2) to an open position with respect to the second piece,

   characterised by the fact that it also comprises a locking unit (5) comprising

   a first locking member (12) on the closure unit (4);

   a second locking member (20) mounted so as to be able to move on the locking unit (5) from an open position to a locking position and vice-versa, first and second locking members being arranged so as to cooperate in the holding of the closure unit (4) in its second stable position when the first piece (1) is in a closed position with respect to the second piece (2) and the second locking member (20) is in the locking position,

   second actuation means (17-19, 21, 22, 25) for moving the second locking member (20) between its open and locking positions, and

   control means (28) for controlling the second actuation means, the said control means comprising control electronics including a microprocessor.
2. A device according to Claim 1, in which the second actuation means (17-19, 21, 22, 25) comprise a DC electric motor (17) and transmission means (21-23) for transmitting the movement of the shaft (19) of the motor to the second locking member (20).
3. A device according to either one of Claims 1 and 2, in which the second actuation means (17-19, 21, 22, 25) comprise elastic return means (25).
4. A device according to any one of Claims 1 to 3, comprising a seal (3) between the first piece (1) and the second piece (2), the first (12) and second (20) locking members being arranged so as to tend to drive the closure unit (4) away from its first stable position from its second stable position when the second locking member (20) is in the locking position, so as to compress the seal (3) when the first piece (1) and the second piece (2) are in the closed position.
5. A device according to any one of Claims 1 to 4, in which the closure unit (4) comprises a fork (7) mounted for rotation on one of the pieces, elastic means (8) being provided for pressing the said fork in one or other direction of rotation away from an unstable equilibrium position.
6. A device according to any one of Claims 1 to 5, in which the first actuation means comprise a first actuation finger (6) mounted on one of the pieces and arranged so as to cooperate in an element (10) of the closure unit (4) mounted so as to be able to move on the other piece between two stable stop positions.
7. A device according to Claims 5 and 6 together, in which the actuation finger (6) is arranged so as to be engaged between the arms (10, 11) of the fork (7) and to push a first arm (11) of the fork when the first piece (1 ) is brought from an open position with respect to the second piece (2) to its closed position with respect to the second piece, and to pull a second arm (10) of the fork when the first piece is brought from its closed position with respect to a second piece to an open position with respect to the second piece.
8. A device according to Claim 7, in which the second arm (10) of the fork (7) is arranged so as to be in abutment on the actuation finger (6) when the closure unit (4) is in its second stable position.
9. A device according to any one of Claims 1 to 8, in which the locking unit (5) comprises a first contact surface (29) arranged so as to come into contact with a second contact surface (31) of the closure unit (4) when the closure unit is in its second stable position and the locking member (20) is in the locking position.
10. A device according to Claims 6 and 9 together, in which the second contact surface (31) is provided on a third arm (12) of the fork (7).
11. A microwave oven characterised by the fact that it comprises a locking device according to any one of Claims 1 to 10.
12. A microwave oven according to Claim 11, comprising a microwave tube and in which the control means (28) are arranged so as to bring the second locking member (20) into its locking position when the microwave tube is activated.
13. A microwave oven according to Claim 12, comprising a locking device according to Claim 2 and in which the control means (28) are arranged so as to maintain an electric current in the DC motor (17) as long as the microwave tube is activated.
14. A method for the rapid locking of a first piece (1) on a second piece (2) with respect to which the first piece is in movement, in particular for a microwave oven door, by means of a device comprising

    a closure unit (4) with two stable stop positions,

    a locking unit (5),

    first actuation means (6) for bringing the closure unit (4) from its first stable position to its second stable position when the first piece is brought from an open position with respect to the second piece to a closed position with respect to the second piece, and to return the closure unit (4) from its second stable position to its first stable position when the first piece is brought from its closed position with respect to the second piece to an open position with respect to the second piece, and

    a first locking member (12) on the closure unit,

    method characterised by the fact that it comprises a step consisting of moving a second locking member (20) mounted so as to be able to move on the locking unit (5) from an open position when the first piece (1) is free to move to a locking position in which the first and second locking members cooperate in the holding of the closure unit in its second stable position when the first piece is in a closed position with respect to the second piece.
15. A rapid locking method according to Claim 14, for locking the door of a microwave oven on the structure of this oven, the said oven comprising a microwave tube and a seal (3) between the door and the structure, a method also comprising a step consisting of keeping the second locking member (20) applied against the first locking member (12) throughout the period where the microwave tube is activated, so as to compress the seal (3) throughout this period.
16. A rapid locking method according to Claim 15, in which, with a view to keeping the second locking member (20) applied against the first locking member (12), an electric current is maintained in a DC motor (17) arranged so as to move the second locking member (20) from its open position to its locked position.

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