EP0273797B1 - Electrical switch - Google Patents

Abstract

Electrical switch comprising a rocking connection blade whose free end is applied, in the closing position, against a fixed part. At a point some way away from this end, there is provided, either on this blade (1) itself, or on the fixed contact part, a boss or other relief (15), the arrangement being such that when the blade (1) rocks in the direction of closing, contact is established firstly at the location of this boss, then also at the end of this blade, and finally only at the end of the latter. When rocking in the direction of opening a reverse process occurs, separation of the contacts taking place at the location of the boss or other relief (15) provided either on the rocking blade (1), or on the fixed contact part. Thus, closure and disconnection take place at a point distinct from the final areas of contact between the connection parts, so that these areas are sheltered from the effects of disconnection and closing arcs. The present switch can be a manually-controlled device or a device comprising any other control system. <IMAGE>

Description

The present invention relates to electrical switches of the type comprising a tilting connecting pallet, the free end of which is applied, in the closed position, against a fixed contact part.

In the case of a manually controlled switch, the tilting of this connecting pallet is generally controlled by a pressure finger carried by an operating lever intended to be actuated by the user.

In general, good quality switches are provided with silver or silver-containing alloy electrical contacts. When the value of the intensity of the current to be cut allows, it is possible to be satisfied with a simple silvering of the contact parts. But in the case of simple devices to be sold at as low a price as possible, the silvering of the contact parts increases this price significantly. This is the reason why most switches of this kind do not have silver parts.

In such a case, the power cut therefore takes place between copper or copper alloy parts. The operating life of such devices is relatively limited because the cutting and closing arcs rapidly oxidize and blacken the contact surfaces. Therefore the contact resistance is not long not increase, which causes significant heating of the contact parts, which often results in the melting of the switch body or that of the control lever.

For certain switches for industrial use, DE-C-143.003 proposed a cut-out device arranged so that the establishment and the breaking of the current occur at the same point, which is different from the main contact point, in order to protect this against erosion and oxidation due to the opening and closing arcs. For this purpose, two separate fixed contacts are provided, intended to serve respectively as a transient contact and as main contact. As for the movable contact, it consists of a finger mounted articulated on the end of a pivoting arm whose rotation, in one direction or the other, causes the closure or separation of the contacts. The articulated finger is subjected to the action of a spring which tends to hold it in the extension of the rotary arm, however allowing its pivoting after it has come to bear against the transient fixed contact, which allows it to come next. resting only against the main fixed contact, when the rotary arm continues to move.

This is therefore a relatively complicated and costly device, all the more so since it is necessary to provide, moreover, a mechanism capable of ensuring the stable maintenance of the moving parts in their two working positions corresponding respectively to the contact closure and separation. The complexity of such a device and its cost cannot therefore allow the adoption of the latter in a small footprint switch intended for electrical installations for equipment of residential premises or offices or the like, for lighting or powering non-industrial electrical devices.

Another switch of this same type is known from patent FR-A 642 678. This switch comprises a movable contact intended to cooperate with two fixed contacts arranged on either side of the movable contact. The movable contact consists of a part articulated around a first axis mounted on a support lever, itself movable around a second axis. When the lever is rotated around the first axis, the extreme edge of the movable contact comes into contact with the extreme edge of the fixed contact. When the lever is continued to rotate around the second axis, the movable contact pivots on the lever around the first axis, the edges move away from each other so that the movable contact and the corresponding fixed contact are found finally in contact with each other at a point relatively distant from the first point of contact. This gives the establishment of a first contact in a location remote from the final operating contact.

Other switches are proposed in US-A 4,045,650 and GB-A 2,170,049, but neither of these switches allows the initial establishment of the current flow and the subsequent breaking of this at a point different from that where the final electrical connection is established. Consequently, they are not capable of solving the problem mentioned in the present application.

This is why the present invention aims to achieve a low cost switch, devoid of any silver or silver contact, and whose design is such that it nevertheless has a considerably greater longevity than switches of the same kind and this, thanks to a very simple arrangement allowing the establishment of the main contact of connection in a point different from that where both the establishment and the breaking of the current.

To this end, the subject of the invention is an electric switch comprising a movable contact actuated by a control member so that the initial establishment of the flow of the current and the subsequent rupture of the latter, take place at a point different from the one where the electrical connection to be made is established, wherein the movable contact comprises a tilting linkage pallet actuated directly by the control member and articulated on a bent end of a metal blade secured to one of the terminals of the device, the free end of the pallet applied, in the closed position, against a blade serving as a fixed contact integral with the other terminal of the apparatus, characterized in that the blade on which the pallet is articulated is an elastic blade and in that it is provided, at a point clearly separated from the free end of the pallet, either on this pallet itself, or on the fixed contact blade, a boss or other relief or, and the arrangement is such that during the tilting of the pallet in the closing direction, the contact is established first at the location of this boss, which constitutes a transient contact, then also at the end of this pallet while maintaining the temporary contact, and finally only at this end who is kills a definitive contact, whereas during a tilting in the direction of the opening there occurs a reverse process, the separation of the contacts taking place at the place of the boss or other relief.

Thus, thanks to very simple and inexpensive means, leading to no increase in the size of the device, the closing and the cutting actually take place at a point different from that or is made the final contact of the connecting parts. This therefore prevents the cutting and closing arcs from oxidizing the surfaces or making normal contact with these parts. Furthermore, the arrangement provided has the advantage that there is, between the two contact zones, a clearance allowing easier extension of the cutting and closing arcs.

In a particular embodiment of the switch according to the invention, in which the tilting connecting pallet is actuated by a pressure finger sliding on this pallet on either side of its axis of articulation, the arrangement is such that during the movement of the pressure finger, in one direction or the other, the bent end of the elastic blade is caused to move approximately in a plane perpendicular to that passing through the base of this blade elastic and the surface of the fixed contact part.

However, other features and advantages of the switch according to the present invention will become apparent during the following description. This relates to a manually operated switch, but the switch according to the invention can just as easily consist of a device actuated by another control mode.

• La figure 1 est une vue en perspective des organes essentiels d'un interrupteur selon l'invention à commande manuelle.
• La figure 2 est une vue en perspective représentant la palette de liaison de cet interrupteur avant son montage sur la lame qui lui sert de support, celle-ci étant partiellement représentée sur cette vue.
• Les figures 3 à 6 sont des vues schématiques en élévation de côté représentant diverses positions successives de la palette de liaison au cours de l'opération de fermeture du présent interrupteur.
• Les figures 7 et 8 sont des vues partielles en perspective illustrant deux autre formes de réalisation du présent interrupteur.

This description is given with reference to the attached drawing for information only, and in which:

• Figure 1 is a perspective view of the essential members of a switch according to the invention with manual control.
• Figure 2 is a perspective view representing the connecting pallet of this switch before it is mounted on the blade which serves as its support, the latter being partially shown in this view.
• Figures 3 to 6 are schematic side elevational views showing various successive positions of the connecting pallet during the closing operation of the present switch.
• Figures 7 and 8 are partial perspective views illustrating two other embodiments of the present switch.

The switch shown in Figure 1 includes a tilting pallet 1 connection, made of copper or other suitable metal. At one of its ends 2, this pallet is mounted articulated on the corresponding end 3 of an elastic metal blade 4 preferably made of copper or copper alloy, secured to one of the terminals 5 of the device.

The end 3 of this blade is bent upwards so that the end 2 of the pallet 1 is supported on its upper edge 6 which in a way materializes the axis of articulation X-Xʹ of the pallet. At this point, the edges of this pallet have two notches 7 in which are engaged two projecting teeth 8 provided on the corresponding end 3 of the elastic blade 4.

The opposite end 9 of the connecting pallet is intended to come into contact with a fixed conductive strip 10, preferably made of copper or a copper alloy, integral with the other terminal 11 of the device and this, during the closing of it. On the other hand, when the end 9 of this pallet is opened, it is kept apart from the fixed blade 10.

As is apparent from the drawings, the flexible blade 4 and the fixed contact blade 10 are situated substantially in the same plane.

The desired movements of the connecting pallet are controlled by a pressure finger 12 which is intended to slide on top of the latter on either side of its axis of articulation X-Xʹ. In the example shown, this pressure finger is integral with an operating lever 13 capable of being actuated manually by the user of the device. The pressure finger 12 and this lever can advantageously be constituted by a molded piece in one piece comprising lateral pins 14 which materialize an axis of articulation Y-Yʹ on the housing of the device.

• une position d'ouverture des contacts qui est représentée à la figure 3 et dans laquelle le doigt de pression 12 est en appui contre l'extrémité 2 de la palette 1 pour maintenir l'extrémité opposée de celle-ci écartée par rapport à la lame de contact 10,
• une position de fermeture des contacts qui est représentée à la figure 6 et dans laquelle le doigt de pression 12 est en appui contre la palette 1 en un point situé au-delà de l'axe X-Xʹ de basculement de celle-ci.

Due to the arrangement provided, the lever-pallet assembly can occupy two extremely stable positions, namely:

• an open position of the contacts which is shown in FIG. 3 and in which the pressing finger 12 is in abutment against the end 2 of the pallet 1 to keep the opposite end of the latter apart from the blade contact 10,
• a closed position of the contacts which is represented in FIG. 6 and in which the pressing finger 12 is in abutment against the pallet 1 at a point situated beyond the axis X-Xʹ of tilting of the latter.

In this latter position, the end part of the free end 9 of the pallet is then kept pressed against the contact blade 10, which ensures the closure of the contacts.

In accordance with the essential characteristic of the invention, the pallet 1 has, at a certain distance from its end 9, a boss 15 projecting in the direction of the contact blade 10. The position of this boss is therefore clearly separated from that of the terminal part of the end 9. This boss can be materialized by a camber of the pallet 1, this camber affecting the shape of a portion of cylinder.

Furthermore, the kinematics of the various moving parts is such that when the pallet 1 is tilted towards its closed position, the latter passes through an intermediate position shown in FIG. 4 and in which the boss 15 thus provided is brought to the contact of the connecting blade 10, while the end 9 of the pallet is not yet. Consequently, a first electrical connection is established at the location of the corresponding zones of the pallet 1 and of the blade 10. It should be noted that in this position, the axis A-Aʹ of the pressure finger 12 coincides with the plane B-Bʹ containing the axis of articulation of the pallet and the axis of articulation of the operating lever, which is perpendicular to the plane passing through the base of the flexible blade 4 and of the contact blade 10.

Furthermore, the end of the blade 4 is then bent. In this regard, it should be observed that the terminal part of this end, which serves as a pivot for the tilting pallet 1, moves during the closing movement in a plane substantially perpendicular to the plane passing through the flexible blade 4 and the surface of the contact blade 10. However, it is this displacement which makes it possible to successively obtain two points of contact between the pallet 1 and the fixed blade 10, as will be explained below.

When the pressure finger 12 continues its movement in the direction of the arrow F, this brings the pallet 1 into the intermediate position shown in FIG. 5. In this one the end part of the end 9 of this pallet is brought in contact with the connecting blade 10 while the boss 15 is still in contact with the latter. Consequently, a closing arc cannot occur at this location since there was already an electrical connection at the location of the boss 15.

Then the further movement of the finger of pressure 12 in the direction of arrow F, has the effect of allowing a release of the pressure exerted on the elastic blade 4 and a more pronounced tilting of the pallet 1. Under these conditions, the boss 15 then moves away from the blade link 10, however that only the end portion of the end 9 of the pallet 1 remains in contact with this blade, which corresponds to the final closed position shown in Figure 6. In this position the final contacts are therefore constituted by the end part of the end 9 of the pallet 1 and the corresponding zone of the connecting blade 10.

During the subsequent opening operation of the contacts, an inverse process takes place. In fact, firstly the pallet 1 comes into the position shown in FIG. 5, in which there is an electrical connection both at the location of its end 9 and of its boss 15. Then it comes in the intermediate position represented in FIG. 4 in which there is only one connection zone, namely: at the location of the boss 15. Under these conditions, the separation of the connection parts takes place at a location different from the zones in which the contacts are made in the normal closed position.

This therefore has the advantage that the closing and cutting arcs are not likely to cause oxidation and blackening of the surfaces on which the final contacts are made. This therefore results in a very low contact resistance and heating, also very low, throughout the lifetime of the device. Furthermore, the very clear spacing of the two successive contact zones of the connecting pallet makes it possible to have a clearance 16 between these two zones. However, this clearance has the effect of facilitating the free expansion of the cutting arcs and of closing, and thereby reduce the risk of particle projections in the area of the final contacts.

It should also be observed that due to the kinematics provided for the moving parts, there is a slight sliding of the terminal part of the end 9 of the pallet 1 between its position of first contact with the blade 10 (FIG. 5) and its final closed position (Figure 6). Of course at the start of the opening maneuver, a similar sliding occurs in the opposite direction. However, these slips, in both directions, have the advantage of ensuring a cleaning by friction of the part of the blade 10 where the final connection contact takes place. This area is therefore kept particularly clean and free of any oxidation.

Consequently, in spite of the absence of silver contacts and of any silvering, the switch according to the invention has a longevity considerably greater than that of current switches of the same kind. This is essentially due to the fact that in the case of the present switch, there is a transient connection contact in addition to the final contact and that the latter takes place at a point other than the transient contact.

In the example described above, this transient contact is materialized by a boss provided on the tilting pallet 1 of connection. However, it could just as easily be provided on the fixed contact part against which this pallet is applied.

Thus, FIG. 7 represents an embodiment in which the corresponding tilting pallet 1a is perfectly flat, while the fixed blade 10a has at the end a bent part 17a projecting in the direction of this pallet. This bent part is located some distance from the part terminal of the end 9 of the pallet la and it is intended to materialize the transient contact provided in this embodiment.

Indeed, in this first contact of the pallet 1a on the blade 10a takes place at the location of the bent part 17 of this blade. Then, the terminal part of the end 9 itself comes into contact with the blade 10a and finally the final contact is ensured only at this last place, the blade la then being moved away from the bent part 17.

This therefore makes it possible to carry out the same process as in the previous embodiment, thus obtaining the same advantages. However, the arrangement of the mechanism remains the same so that it is unnecessary to describe it again.

FIG. 8 represents a variant of this embodiment. In it the corresponding tilting pallet 1a is also flat. As for the fixed blade 10b, it has a bent portion 17b similar to that provided in the case of Figure 7. However there is an opening 18 at this location which has the function of further facilitating the expansion of the arc of cut to avoid any soiling of the area of the final contact.

However, many other embodiments of the present switch can be provided. Thus, the shape of the boss or other relief serving as a transient contact, either on the connecting pallet or on the fixed contact piece, could be different from that previously provided. Furthermore, as already indicated, the switch according to the invention is not limited to a device with manual control of the type described above, because it can just as easily consist of a device actuated by another control mode , for example an electromagnetic relay.

Claims (5)

1. An electrical switch comprising a movable contact piece actuated by a control member so that the initial bringing-in of the passage of the current, and the subsequent breaking of the current, take place at a point being different from the point where the electrical connection to be made will be established, wherein the movable contact piece comprises a rocking paddle-shapedconnecting blade (1, 1a, 1b) directly actuated by the control member and hinged about one angled end (3) of a metal blade (4) bound up with one terminal (5) of the switch, the free end (9) of the paddle being applied, in the closing position, against a blade (10, 10a, 10b) serving as a fixed contact piece bound up with the other terminal (11) of the switch, characterized in that the blade about which the paddle is hinged is a resilient blade and in that there is provided, in a spot being markedly separate from the free end of the paddle (1), either on the paddle itself or on the fixed contact blade (10a, 10b), a boss or a similar raised portion (15, or 17a, 17b) the arrangement being such that, during the rocking motion of the paddle (1, 1a, 1b) in the direction of closing, the contact is first established at the site of said boss, which constitutes a transient contact, and then also at the end of said paddle, while maintaining the transient contact, and finally only at said end, which constitutes a final contact, whereas, during a rocking motion in the contact-breaking direction, an opposite process takes place, the separation of the contact pieces occurring at the site of the boss or other raised portion (15, 17a, 17b).
2. An electrical switch according to Claim 1, characterized in that the rocking connecting paddle (1, 1a, 1b) being actuated by a pressurefinger (12) sliding along said paddle on either side of its hinging axis, the arrangement is such that during the displacement of said pressure finger in either direction, the angled end (3) of the resilient blade (4) is caused to move substantially in a plane perpendicular to the plane passing through said resilient blade and through the surface of the fixed contact piece (10, 10a, 10b).
3. An electrical switch according to Claim 1 or 2, characterized in that the boss or other raised portion intended for serving for the transient contact being provided on the rocking connecting paddle (1), said boss consists in an arched portion (15) of said paddle, the convexity of said arch being directed towards the fixed contact piece (10).
4. An electrical switch according to Claim 1 or 2, characterized in that the boss or other raised portion intended for serving for the transient contact being provided on the fixed contact piece (10a, 10b), said boss consists in a bent portion (17a, 17b) provided on the end of the blade forming said piece, said bent portion protruding towards the rocking connecting paddle (1a, 1b).
5. An electrical switch according to Claim 4, characterized in that the bent portion (17b) provided on the end of the fixed contact blade (10b) comprises an opening (18).

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