EP0167429B1 - Multidirection switch commanded by a ball - Google Patents

Description

The present invention relates to a multi-directional switch which can be used in particular as a safety switch in a heating device such as an electric heater.

It has been noted on various occasions that certain appliances, in particular household appliances, must include a safety switch sensitive to a shock on the appliance or to an inclination of the latter in order to cut the supply to the appliance. In particular, in the case of a portable electric heater, there is a significant risk of fire if the electric heater is knocked against flammable objects or placed on an uneven surface, so that the heating element is near a flammable object.

The safety switches known to date generally include a pendulum associated with electrical contacts in the supply circuit to ensure a connection between these contacts when the device is in the normal position of use and to interrupt the supply circuit. when the apparatus receives a shock beyond a predetermined threshold or is inclined beyond a predetermined angle according to the characteristics of the apparatus.

It is also known to produce safety switches comprising a sensitive element in the form of a ball normally disposed above a switch of the push button type to close the electrical supply circuit during a normal position of the 'apparatus. When the device receives a shock or is tilted, the ball escapes and releases the push button which opens the electrical supply circuit. Cy type of safety switch is of a lower cost price than safety switches comprising a pendulum because the ball is of a cost price generally appreciably lower than the cost price of a pendulum. However, these switches have the drawback of not being resettable. Indeed, when the pusher is out and the device returned to the normal position, the ball abuts on the side of the pusher and cannot therefore act on it to close the switch. The switch must therefore be reset manually, which poses problems for users who are not familiar with the technique.

Document US-A-4255629 describes a switch which, by its spring structure, to say the least, fairly complex and of high inertia, only trips under the effect of a sudden shock, so that its sensitivity is reduced. In addition, the presence of springs and variations in tolerances are rarely mastered in manufacturing also increases the difficulty of production.

The document DE-B-1287675 describes a ball switch which does not work when it is returned because it has no means for holding the ball or balls in their guide device. In addition, the structure proposed by this document does not provide omnidirectional sensitivity and it is also difficult to see how to miniaturize it sufficiently so that the corresponding switch can be integrated in a small domestic appliance.

In summary, none of the lessons from the two aforementioned documents makes it possible to obtain an actuating member supported in a housing by means which make it possible to obtain a multidirectional switch intended in particular to be mounted on household appliances which function whatever the inclination taken by the device or the orientation of the shock to which the device is subjected and which is of very simple structure resulting in low manufacturing and assembly costs while being sufficiently sensitive.

An object of the present invention is to provide a multi-directional switch with a low cost price, which is nevertheless automatically resettable when the device on which the switch is mounted is in normal operating conditions and which, d 'in general, does not have the drawbacks of known devices.

In order to achieve this goal, there is provided according to the invention a multi-directional switch comprising at least two electrical contacts carried by a housing, one of these contacts being movable between a closed position and an open position, a member of movable actuation in the housing and having a control part for actuating the movable contact as well as a cup-shaped recess opening on the side opposite the contacts, first and second tilting support means respectively provided on the member actuation and in the housing and adapted to engage, these support means being located radially between the region of the deepest of the cup-shaped recess and the outer edge thereof, and a ball movable in the recess in the form of a bowl, the housing being internally shaped to limit the movements of the actuating member and of the ball and to maintain on the one hand the ball in the bowl-shaped recess and on the other hand the prem ier and second tilting support means one opposite the other, characterized in that the control part maintains the movable contact in one of its positions when the actuating member and the ball are in a rest position in which the first and second tilting support means are engaged all around said deepest region and in that the control part maintains the movable contact in its other position when the actuating member and the ball are in a triggered position in which the first and second tilting support means are at least partially disengaged from each other.

Because the first tilting support means is arranged radially between the deepest region of the cup-shaped recess (the central region of the recess in the example) and the outer edge of this recess, the actuating member is moved by the ball when the latter is adjacent to said deepest region of the recess or at the outer edge thereof.

Thus, the contacts will be in their closed position corresponding to the rest position of the actuating member and of the ball when the cup-shaped recess is oriented upwards, that is to say when the part control will be supported on the movable contact, while these contacts will be in their open position corresponding to the triggered position of the actuating member and the ball when the cup-shaped recess is oriented in any lateral direction, that is to say when the control part will no longer be supported on the movable contact.

When the switch returns to the normal position in which the actuating member is directed upwards, the ball is replaced in the bottom of the cup-shaped recess and the contacts return to the closed position.

In particular, it is the weight of the ball in its normal position which determines the closed position of the contacts. Thus, if the ball is forgotten by the fitter during assembly of the device, the contacts will automatically be in the open (or tripped) position, which constitutes positive security.

Other features and advantages of the invention are set out in subclaims 2 to 10.

• La fig. 1 est une vue en coupe selon le plan 1-1 de la fig. 2 dans la position de repos de l'interrupteur;
• la fig. 2 est une vue de dessus de l'interrupteur en position de repos;
• la fig. 3 est une vue en coupe selon le plan III-III de la fig. 2;
• la fig. 4 est une vue de dessus d'un support de contact électrique;
• la fig. 5 est une vue en perspective du couvercle.

Other characteristics and advantages of the invention will also result from the following description of a nonlimiting example with reference to the appended drawings in which:

• Fig. 1 is a sectional view along the plane 1-1 of FIG. 2 in the rest position of the switch;
• fig. 2 is a top view of the switch in the rest position;
• fig. 3 is a sectional view along the plane III-III of FIG. 2;
• fig. 4 is a top view of an electrical contact support;
• fig. 5 is a perspective view of the cover.

With reference to the figures, the multi-directional switch comprises a generally cylindrical housing 1, in which two electrical contacts 2 and 3 are arranged facing each other and a control ball 4 used for closing an electrical circuit between the electrical contacts 2 , 3.

According to the invention, the switch comprises a tilting member 5 forming an actuating member supported in the housing 1 by a tilting part 6 forming a first tilting support means, and comprising a control part 7 extending in the vicinity of the support plate 8 of the electrical contact 3, the ball 4 being carried by a surface 9 of the rocking member 5 opposite the rocking part 6 and forming a recess with a bowl profile.

The tilting part is a shoulder having a sharp edge 6 set back relative to the edge of the surface 9 of the tilting member 5 carrying the ball 4. In the embodiment shown, the sharp edge 6 is formed by the edge bottom of a rigid skirt 10, extending downward from the underside of the tilting member 5.

At its lower part, the housing 1 comprises a narrowed part 11 forming an abutment surface for the tilting part 6. More particularly, the rigid skirt 10, one edge 6 of which forms the tilting part rests in the bottom of the housing 1 and is held on one side by the lower part 11 of the side wall of the housing 1 and on the other side by a circular rib 12 provided in the bottom of the housing 1 and forming second tilting support means.

At its upper part, the housing 1 comprises a tail 13 pierced with an opening 14 used to fix the multidirectional switch in the device for which it must ensure security. The housing 1 also has upper edges 15 which are largely indented and allow easy access to the interior of the housing.

The contact 3 is carried by a rectangular support blade 8, comprising a central tongue 16 (fig. 4) which carries the contact 3. The end of the blade 8 to which the tongue 16 is connected is movable while the end of the blade 8 opposite to that to which the tongue 16 is connected is held in the housing. This makes it possible to obtain a large elastic displacement distance for the contact 3 while keeping reduced dimensions for the support blade 8.

The bowl-shaped surface 9 is preferably frustoconical and the tilting part 6 extends around the axis of the bowl, so that the tilting member 5 can tilt in any direction. In particular, in the case of a rigid circular skirt 10, the tilting part formed by the edge 6 of this skirt is a circular edge coaxial with the frustoconical surface 9.

In the illustrated embodiment, the cup-shaped surface 9 has a central part 18 having a first inclination and a peripheral part 19 having a greater inclination than the central part 18, so that when the ball 4 reaches the peripheral part 19, the tilting torque exerted on the tilting member 5 is increased.

The control part 7 is preferably a finger coaxial with the bowl-shaped surface 9 and the tilting part 6 and extending through the bottom of the housing 1. To prevent the finger 7 from escaping from the opening in which it is inserted during the tilting of the tilting member 5, there is advantageously provided a rib 20 surrounding the opening in which the finger extends 7. Although for manufacturing reasons the ribs 12 and 20 have been shown separately, it will be understood that these two ribs can be joined in a single annular band surrounding the central opening in the bottom of the housing.

To prevent the ball 4 from escaping when the switch is turned over, a cover 21 in the form of a bar is provided, the internal surface of which has a profile for pressing without jamming the ball 4, when the switch is tilted. In particular, the bar is formed of two side walls 22 (see fig. 2 and 5) joined together by intermediate walls 23 supporting a cross Ion 24, the central part of which extends downwards to form a point 25 (fig. 3). The walls 22 also have at their end portions 26 projecting downward relative to the median edges 27. Thus, the face of the bar facing the ball 4 has a profile in the form of a zig zag (see FIG. 3).

The cover 21 is preferably held in openings in the side wall of the housing 1 and has shoulders 28 which cooperate with flexible hook-shaped tongues 29 (FIG. 2) made in one piece with the side wall of the housing 1 .

When the switch is in the normal operating position, the tilting member 5 rests on the bottom of the housing 1 and the finger 7 extends through the bottom to press on the support blade 8 and maintain the contact 3 pressed on the contact 2. The electrical circuit is then closed. When the switch is shocked or tilted, the ball 4 rolls along the surface 9 supporting it and, when the torque created by the ball 4 around the tilting part 6 added to the torque resulting from the elastic force of the support blade 8 compensates for the torque resulting from the weight of the rocking member 5, applied to its center of gravity, the rocking member 5 swings suddenly and the contact 3 separates from the contact 2 thus opening the electrical circuit.

As soon as the cause of the movement of the ball 4 towards the edge of the surface 9 has disappeared, and due to the bowl shape of this surface, the ball returns to its rest position and the electrical circuit is automatically closed.

Of course, the invention is not limited to the embodiment described above and it is possible to make variant embodiments. In particular, the lower end of the control part 7 can be conductive and the contacts 2 and 3 can be arranged opposite one another, on either side of the end of the finger 7 so that the two contacts are joined by the conductive part of the control part, when the latter is in the rest position.

The tilting member may be of small dimensions and be arranged in the center of a housing comprising an inclined wall extending the bowl shape of the tilting member.

The tilting member may be of a shape other than a circular shape, for example with a rectangular surface held on the sides and able to tilt only in one or more given directions.

Instead of being disposed at the bottom of the tilting member 5, the control member 7 may be disposed on the side of the tilting member, for example by extending from one of its edges .

The surface 9 of the tilting member can be offset from the tilting stop 6 to create a preferred tilting orientation.

Claims (10)

1. A multi-directional switch comprising at least two electrical contacts (2, 3) borne by a casing (1), one of said contacts being movable between a closed position and an open position, an actuating member (5) movable in the casing (1) and having a control part (7) to actuate the movable contact and a dish-shaped recess opening on the side remote from the contacts (2, 3), first and second rocking support means (6, 12) respectively provided on the actuating member (5) and in the casing (1) and adapted to inter-engage, said support means (6,12) being situated radially between the deepest zone of the dish-shaped recess and the outer edge thereof, and a ball (4) movable in the dish-shaped recess, the casing (1) being internally shaped to limit-the movements of the actuating member (5) and of the ball (4) and, on the one hand, to hold the ball (4) in the dish-shaped recess and, on the other hand, the first and second rocking support means (6, 12) facing one another, characterised in that the control part (7) holds the movable contact in one of its positions when the actuating member (5) and the ball (4) are in an inoperative position in which the first and second rocking support means are inter-engaged all around the said deepest zone and in that the control part (7) holds the movable contact in its other position when the actuating member (5) and the ball (4) are in a tripped position in which the first and second rocking support means are at least partially disengaged from one another.

2. A switch according to claim 1, characterised in that the first rocking support means is a shoulder having at least one sharp ege (6) which is set back from the edge of the surface (9) of the actuating member (5) bearing the ball (4).

3. A switch according to claim 1 or claim 2, characterised in that the first rocking support means (6) co-operates with an abutment surface (11) borne by the casing (1).

4. A switch according to claim 3, characterised in that the actuating member (5) rests in the base of the casing (1) and comprises a rigid skirt (10), one edge (6) of which forms the first rocking support means and in that the rigid skirt (10) is held on one side by the side wall (11) of the casing (1) and on the other side by a rib (12) provided in the base of the casing (1) and forming the second rocking support means.

5. A switch according to any one of claims 2 to 4, characterised in that the surface (9) of the actuating member (5) which forms the dish-shaped recess is frusto-conical and in that the first rocking support means (6) extends around the axis of the dish.

6. A switch according to claim 5, characterised in that the first rocking support means is a circular edge coaxial with the frusto-conical surface (9).

7. A switch according to any one of claims 2 to 6, characterised in that the surface (9) of the actuating member (5) has a central part (18) having a first inclination and a peripheral part (19) having a greater inclination than that of the central part (18).

8. A switch according to any one of claims 2 to 7, characterised in that the control part (7) is a finger coaxial with the surface (9) of the actuating member (5) and with the first rocking support means (6) and extending through the base of the casing (1).

9. A switch according to any one of claims 1 to 8, characterised in that it comprises a cover (21), the inner surface of which has a profile for a support without jamming of the control ball (4) when the switch is inclined.

10. A switch according to claim 9, characterised in that the cover (21) is a bar whose surface facing the ball (4) has a zig-zag profile.

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