EP1244123A1 - Device for assuring the passage of an electric current between articulated conductive arms - Google Patents

Abstract

The swinging arm conductor unit has two arm sections (10,20) swinging about a pivoting axis (X). The mechanism has a cylindrical pivot (31) with a fixed end (34) fixed to the first conductor and a second end on the maintenance edge. There is a flexible section (32) on the maintenance edge attached to the external face (22) of the conductor.

Description

The present invention relates to a device ensuring the passage of a electric current between several articulated conducting arms. This device is particularly suitable for the passage of strong permanent currents at low voltage and is also capable of withstanding exceptional short circuit currents. The invention also relates to an electrical appliance comprising at least one such device.

The articulated devices ensuring the passage of an electric current are especially used in electrical devices such as switches, circuit breakers or contactor-circuit breakers to advantageously replace a contact braid placed between a fixed conductor and a connected articulated mobile conductor electrically with the fixed conductor. A braid poses problems indeed size, heating, manufacturing cost and mechanical effort in especially when passing a strong current. In addition, a flexible blade device is also not suitable for the passage of strong permanent currents. A device articulated allows on the contrary to correctly pass a strong current provided to have a sufficiently well defined and controlled contact area to guarantee a low contact resistance and to avoid any risk of welding in the joint.

The document EP0358286 already describes an articulation device for the passage of strong electric current. This device includes an articulation zone surrounding the pivot axis of a movable contact lever. A fixed conductor has two conductive ends which grip the area like pincers of articulation of the movable contact lever, on at least three contact points. The OR the different contact planes thus created are therefore substantially parallel to the axis of pivoting. However, this solution on the one hand calls for a number of parts important and on the other hand does not allow to obtain a precise and constant dosage of the contact pressure, allowing to take into account the manufacturing tolerances of different rooms. In addition, increase the tightening around the contact area risk of jamming when the movable contact is pivoted, unless to provide a larger clearance, which then no longer ensures the maintenance of a satisfactory contact.

Documents US2256815 and US2546366 also describe devices for the passage of electric current between several articulated conductors around an axis. In these devices, certain conductors have bosses at the level of the joint, thus making it possible to facilitate their rotation against other conductors by forming a contact plane perpendicular to the axis of the joint. However, these devices do not provide anything to ensure a pressure effort of effective, stable and homogeneous contact in the joint, even in the event of wear of the contact areas.

The present invention therefore aims to design a device ensuring the passage of a strong electric current between two or more articulated conducting arms. This device must be simple, require few parts and must allow adjustment easily at a determined threshold the contact clamping pressure during manufacture of each device, so as to obtain a high predefined, stable contact pressure and homogeneous on real passage sections without hampering the movement of the articulation of the conductive arms. This contact pressure should be easily reproducible during mass production of this device.

For this, the invention describes a device intended to ensure the passage of a electric current in a set of conductive arms comprising at least one first extreme conductive arm and a second opposite extreme conductive arm, all of the conductive arms being articulated relative to each other according to a pivot axis. The device comprises a through cylindrical pivot all of the conducting arms in a direction parallel to the pivot axis and having two ends, a first end of the pivot being fixed to the first extreme conductive arm and a second end comprising a retaining edge, and the device comprises an elastic member located between the retaining flange and a external face of the second opposite extreme conducting arm.

To obtain a constant contact pressure, the first end of the pivot is fixed after application of a predefined pressure force between the arm extreme conductor and the pivot retaining edge, by a welding operation, bonding or crimping.

According to one characteristic, an internal face of a second conductive arm of the conductive arm assembly comprises several contact zones which are in contact with a flat surface of an internal face of a first conductive arm, adjacent to the second conductive arm, forming a contact plane perpendicular to the pivot axis.

The contact areas advantageously consist of three bosses convex, of identical size, having a rounded or hemispherical shape and uniformly distributed on the internal face of the second arm.

• la figure 1 représente un dispositif selon l'invention assurant le passage d'un courant électrique entre deux bras conducteurs,
• les figures 2, 3 et 4 montrent des variantes du même dispositif mais possédant plus que deux bras conducteurs,
• la figure 5 détaille une vue de dessus d'un bras conducteur conforme à la figure 1.

Other characteristics and advantages will appear in the detailed description which follows, with reference to an embodiment given by way of example and represented by the appended drawings in which:

• FIG. 1 represents a device according to the invention ensuring the passage of an electric current between two conducting arms,
• FIGS. 2, 3 and 4 show variants of the same device but having more than two conductive arms,
• FIG. 5 details a top view of a conductive arm in accordance with FIG. 1.

With reference to an embodiment shown diagrammatically in FIG. 1, a device 5 passage of an electric current comprises a set of conductive arms composed of a first arm 10 and a second arm 20. These arms are electrical conductors and are made for example from copper. They are articulated with respect to each other along a pivot axis X. The object of the invention is to get the best electrical contact at the joint between the arms conductors without penalizing the articulation movement too much. This device can be used in an electrical device of the switch, circuit breaker or contactor-breaker type to advantageously replace a contact braid placed between a fixed conductor and a movable conductor electrically connected to the fixed conductor. Indifferently, it is any one of the conductive arms 10, 20 which is fixed by relative to the electrical device and the other which is movable along the pivot axis X.

The conductive arms 10, respectively 20, comprise, in an area close to the joint, an internal face 11, respectively 21, and an external face 12, respectively 22, substantially parallel to each other. One of the two arms conductors, for example the first arm 10 in the example of FIG. 1, has a flat surface on its internal face 11. This flat surface is preferably circular to cover a rotation around the pivot axis X. The other arm conductor, the second arm 20 in the example of FIG. 1, has several zones of contacts 30 on its internal face 21. These contact zones 30 come into contact with the planar surface of the internal face 11 of the first arm 10, thus forming a plane contact which is substantially perpendicular to the pivot axis X. In a way preferred, there are three contact areas of identical size so as to define precisely the contact plane.

The contact areas may consist of three bosses 30 convex, prominent and uniformly distributed on the internal face 21. These bosses 30 are produced for example by pushing back on the conductive arm 20 and are preferably rounded or hemispherical, although we can also consider a triangular shape or a flat shape. Figure 5 details a view from above a second conductive arm 20 in which the three bosses 30 are positioned on the internal face 21, at an angle of about 120 ° between them, around of the pivot axis X. The surface of the bosses 30 can be covered with a deposit silver to improve electrical contact or even a graphite silver deposit for limit the risks of welding. During movements, the bosses facilitate also the evacuation of any debris or dust between the conductive arms, likely to obstruct the flow of current and cause possible jamming of the joint.

The mechanism described in this device according to the invention allows consider many variations for a joint with more than two conductive arms, such as those shown in FIGS. 2, 3 and 4 in which the device ensuring the passage of an electric current has for example three arms conductors in the examples of Figures 2 and 4 and five conductive arms in the example of figure 3. The contact areas of figures 2, 3 and 4 are similar to those described for figure 1.

Figure 2 shows a set of conductive arms consisting of an arm upper conductor 100, a middle conductive arm 200 and a conductive arm lower 110. The upper arm 100 and the lower arm 110 constitute the arms extremes and each have an external face 102 (respectively 112) turned towards the outside of the device and an internal face 101 (respectively 111) facing inside the device. The external and internal faces are substantially parallel between them. The middle arm 200 has an upper face 202 facing the arm upper 100 and substantially parallel to the internal face 101, as well as a face lower 201 facing the lower arm 110 and substantially parallel to the face internal 111. The upper face 202 of the middle arm 200 has a flat surface which is in contact with several contact zones present on the internal face 101 of the upper arm 100, analogously to what has been described previously in reference to FIG. 1. The underside 201 of the median arm 200 comprises several contact areas which are in contact with a flat surface on the face internal 111 of the lower arm 110. The upper 100 and lower 110 arms are therefore placed on either side of the middle arm 200 so as to obtain a joint between conductors 100 and 200 on the one hand and between conductors 110 and 200 on the other hand.

In the variant of FIG. 4, a median conductive arm 140 has several contact zones on its lower face as well as on its upper face. The contact areas of the upper face of the middle arm 140 are in contact with the flat surface of an internal face of an upper arm 220, while the zones of contact of the underside of the middle arm 140 are in contact with the flat surface of an inner face of a lower arm 230. It can be envisaged that the upper arm 220 and the lower arm 230 are then connected together to form a single arm 240. In this case, the conductive arms 220 and 230 must be sufficiently elastic to guarantee contact pressure. Furthermore, if the two series of zones of contact of the median arm 140 each consist of three bosses obtained by pushed back and distributed at 120 °, it is possible to offset by 60 ° the two series of bosses (see Figure 4) relative to each other, to allow a more Easy.

Thus, the device described in FIG. 4 has the advantage of doubling the contact zones with respect to the device of FIG. 1 since the conductive arm median 140 is in contact with the single arm 240 by means of two series of zones contact instead of a single series, which allows to increase the surfaces of contact of the joint and therefore the intensity of the admissible current in the joint.

The device shown schematically in Figure 3 includes a conductive arm upper 120, a lower conducting arm 130 and two conducting arms 125,135 intermediaries surrounding a median conductive arm 210. The median arm 210 has two flat surfaces on its two upper and lower faces. The arm intermediate 125 has a lower face comprising several contact zones which are in contact with the flat surface of the upper face of the middle arm 210. The upper arm 120 has an internal face comprising several zones of contacts that are in contact with a flat surface on the upper side of the arm intermediate 125. Similarly, the intermediate arm 135 has an upper face comprising several contact zones which are in contact with the flat surface of the lower face of the middle arm 210. The lower arm 130 has an internal face comprising several contact zones which are in contact with a flat surface on the underside of the intermediate arm 135.

The fact of being able to easily multiply the conducting arms at the level of the joint thus makes it possible to use the device of the present invention in electrical devices of a caliber requiring greater electrical intensity.

The device according to the invention also comprises, for holding the arms conductors between them, a cylindrical pivot 31 which is introduced into a circular hole central present in each conductive arm. The pivot 31 crosses the different arms conductors of the device in a direction parallel to the pivot axis X. In Figure 5 is shown a top view of a second conductive arm 20 conforms in Figure 1 in which the conductive arm 20 has a circular central hole 23 for the introduction of the pivot 31, surrounded by three bosses 30 uniformly distributed and making an angle of about 120 ° between them.

The cylindrical pivot 31 has two opposite ends. A first end 34 is fixed to an extreme conductive arm. We mean by conductive arm extreme one arm located at one end of the set of conductive arms, that is to say for example either the first conductive arm 10 in FIG. 1, or the arm upper conductor 100,120,220 in Figures 2, 3 and 4. The second end of the pivot 31 has a retaining flange 33. The device also includes a elastic member 32 which is positioned between the retaining rim 33 and the external face 22,112 of an opposite extreme conductive arm. By extreme conductive arm opposite an arm located at the opposite end of the conductive arm assembly, i.e. for example either the second conductive arm 20 in FIG. 1, or the arm lower conductor 110,130,230 in Figures 2, 3 and 4.

The elastic member consists of a spring or preferably of a elastic washer 32 (such as a "Belleville" type washer), for example of shape conical, advantageous for reasons of compactness. The size of this elastic washer 32 is adapted so that once mounted, it can get stuck between the retaining flange 33 of the pivot 31 and the external face of the conductive arm extreme opposite 20,110,130,230.

Thanks to the elastic washer 32, it is possible, during the assembly of the device described, to easily exert a pressure force of a predefined value, between the retaining edge 33 of the pivot 31 and the extreme conductive arm 10,100,120,220. This provides a constant contact pressure at the level different contact areas 30 of the device. Once this effort value of pressure obtained, and for example measured by any means of measurement already known, we then fixes the first end 34 of the pivot 31 on the external face 12, 102 of the arm extreme conductor 10,100,120,220 for example by means of an operation of welding, bonding or crimping, thus making the different arms integral conductors, pivot and spring washer. In an entirely equivalent way, we could use pivot 31 by reversing its two ends with respect to the arms device conductors.

The measurement at a predetermined value of the pressure force exerted before the fixing the first end 34 of the pivot 31 makes it possible to obtain automatically, during the manufacturing processes of such devices, uniform pressure and stable on contact areas, regardless of imperfections and tolerances different parts constituting the device. This is essential to obtain reproducible in time a pivoting of the articulated arms without friction excessive as well as an optimal quality of contact between the articulated arms, capable of withstand strong strong currents and resist electrodynamic forces during a short circuit.

The cylindrical pivot 31 is for example made of steel or dural without special characteristic of electrical conduction. Indeed, in the device described above, most of the current flowing through the joints propagates to through the contact areas 30 and not through the pivot 31.

It is understood that one can, without departing from the scope of the invention, imagine other variations and refinements of detail and likewise consider the use of equivalent means.

Claims (8)

Device for ensuring the passage of an electric current in a set of conductive arms of an electrical appliance comprising at least a first extreme conductive arm (10,100,120,220) and a second extreme conductive arm (20,110,130,230) opposite, all of the conductive arms being articulated with respect to each other along a pivot axis (X), characterized in that the device comprises a cylindrical pivot (31) passing through all of the conducting arms in a direction parallel to the pivot axis (X ) and comprising a first end (34) fixed to the first extreme conductive arm (10,100,120,220) and a second end provided with a retaining flange (33), and by the fact that the device comprises an elastic member (32) located between the retaining rim (33) and an external face (22,112) of the second extreme conductive arm (20,110,130,230) opposite. Device according to claim 1, characterized in that the first end (34) of the pivot (31) is fixed after application of a pressure force of a predefined value between the first extreme conductive arm (10,100,120,220) and the flange of retaining (33) of the pivot (31). Device according to claim 2, characterized in that the first end (34) of the pivot (31) is fixed to the external face of the first extreme conductive arm (10,100,120,220) by a welding, gluing or crimping operation. Device according to claim 1, characterized in that the elastic member consists of an elastic washer (32). Device according to claim 1, characterized in that an internal face (21) of a second conductive arm (20) of the set of conductive arms comprises several contact zones (30) which are in contact with a flat surface an internal face (11) of a first conductive arm (10), adjacent to the second conductive arm (20), forming a contact plane perpendicular to the pivot axis (X). Device according to claim 5, characterized in that the contact zones consist of three convex bosses (30) uniformly distributed on the internal face (21) of the second conductive arm (20). Device according to claim 6, characterized in that the bosses (30) are of identical size and have a rounded shape. Electrical switch device comprising at least one device according to one of the preceding claims.

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