EP1139358B1 - Electrical switching device having a vacuum bottle and a flexible electrical connection - Google Patents

Description

The invention relates to an electrical switchgear comprising a movable rod and a flexible electrical connection between the movable rod and a fixed connection range.

EP 0 058 519 discloses a switchgear including the contact member mobile comprises a cylindrical rod movable in translation along its axis. This stem is connected to an external connection area via a flexible conductor constituted by a stack of metal strips. Each metal strip has a circular opening with legs protruding out of the plane of the metal band, towards the center of the opening. To mount the flexible conductor on the stem, the rod is inserted in the openings of the strips, then we take the sandwich drivers between two clamping plates. The plates are connected to each other by bolts. When one tighten the bolts, the plates tend to compress the metal strips of the driver flexible in the region with openings, causing deformation and creep legs in contact with the rod.

Such a connection requires a fairly long assembly time. In addition, it implements massive mechanical parts that must move with the stem during openings and Closures of the apparatus. It follows that the energies of opening and closing are high, and that the shocks caused at the end of the race also have a high energy. The entire opening and closing mechanism of the switchgear shall then be dimensioned so as to be able to provide such energies of opening and closing, and to be able to withstand the corresponding shock energies. Moreover, the stem temperature increases when the bulb is traversed by a nominal current, until, at the level of the flexible conductor attachment, the order of 100 ° C and more. At such temperatures, the screwing does not appear as a reliable solution over time.

It has been proposed in US Pat. No. 5,530,216, corresponding to the preamble of claim 1, to directly attach a link flexible electrical device consisting of a stack of metal strips, at the stem of a Vacuum bulb, without the use of clamping plates. The stack comprises two rigid end regions and a flexible median region. One of the end regions has an opening with legs protruding out of the plane of the opening. A Once the rod is inserted into the opening, a press fitted with a ring tool press the tabs so that they are a fit in force on the rod. Once the tool is removed, the rod and the flexible electrical connection are secured to one another. This fixing process imposes high mechanical stresses on the rod during assembly. Gold the mobile equipment of a vacuum interrupter is fragile, and should not be used outside its axis of translation. Care must be taken to avoid damage the bulb when fixing the connection. In addition, it should be noted that the area adjustment in force, which ensures the passage of current between the rod and the driver mobile, has a high resistivity and that it is subjected, during the passage of the current nominal temperature, to a temperature rise which tends to cause differential different elements, because of differences in the coefficients of expansion of the materials components of the stem on the one hand, and the stack of metal plates on the other. AT this dilation effect is added to the tendency of materials to flow under the influence of temperature, particularly in the force adjustment zone. In addition, any primer local deterioration of the junction tends to increase over time as it locally causes an increase in resistivity that causes a rise in temperature. The reliability of the binding is reduced.

The invention therefore aims to remedy the drawbacks of the state of the art and to propose a junction zone between the movable rod of a switchgear and a link flexible electrical system, which has excellent current conduction properties, which is light, reliable in time, and simple to manufacture.

• une ampoule à vide comportant corps formant une enceinte renfermant une paire de contacts, séparable, un desdits contacts étant solidaire d'une tige métallique mobile en translation, une partie de la tige faisant saillie hors de l'enceinte de l'ampoule ;
• une liaison électrique métallique flexible destinée à relier électriquement la tige au jeu de barres, la liaison flexible étant constituée par un empilement de lames métalliques et comportant une première partie d'extrémité rigide définissant un alésage dans lequel est insérée la partie saillante de la tige ;

caractérisé en ce que :

• les lames métalliques sont assemblées les unes aux autres par soudure au niveau de ladite première partie d'extrémité rigide, de manière à former à ce niveau un ensemble monobloc,
• la liaison électrique flexible est fixée à la partie saillante de la tige au moyen d'une brasure entre la partie saillante de la tige et la première partie d'extrémité rigide.

According to the invention, this problem is solved by means of an electrical switchgear intended to be electrically connected to a busbar and comprising:

• a vacuum interrupter comprising a body forming a chamber enclosing a pair of separable contacts, one of said contacts being integral with a metal rod movable in translation, a portion of the rod projecting from the chamber of the bulb;
• a flexible metal electrical connection for electrically connecting the rod to the busbar, the flexible connection being constituted by a stack of metal blades and having a first rigid end portion defining a bore into which is inserted the projecting portion of the rod;

characterized in that

• the metal blades are joined to each other by welding at said first rigid end portion, so as to form at this level a one-piece assembly,
• the flexible electrical connection is attached to the projecting portion of the rod by means of solder between the projecting portion of the rod and the first rigid end portion.

The one-piece assembly constituted by the welded assembly of the metal blades at the level of of the first rigid end portion, ensures a good mechanical strength of all. Brazing provides a metallurgical connection between the rod and the driver flexible. The metal feed compound has a determined melting point, depending on the chemical elements constituting it, lower than the melting points of metal parts that it allows to bind. Indeed, the parts to join, in this case the rod and the connector flexible, must not participate by fusion in the constitution of the joint during the assembly pieces.

This mode of fixation had not been considered so far, probably because it implies in the process a heating step felt like crippling. Indeed, the light bulb itself has solders and materials sensitive to high temperatures. he therefore, the heating step necessary for brazing the rod and the connection must be avoided flexible does not damage the bulb. That's why we chose a metal composition whose melting point is not very high, that is to say, in the context of the present invention, lower than the temperature likely to damage the bulb. In particular, if the bulb has a sealing bellows brazed on the stem, we will choose for the solder for fixing the flexible electrical connection to the rod, a solder having a melting temperature lower than that used to braze the bellows on the rod.

It suffices to avoid any deterioration of the bulb during soldering of the connection electric, that the melting point of the solder is substantially less than 900 ° C, and preferably less than 700 ° C. However, the choice of a solder at a temperature of low melting must not be done to the detriment of the electrical conductivity of the brazing, nor to the detriment of its mechanical strength. Preferably, the metal compound is a silver-based compound in proportions greater than 30%, with a tin content in proportions of less than 10%. In particular, we will prefer proportions greater than 50% in silver, with a contribution of tin in proportions less than 6%. Silver gives the solder excellent electrical conductivity. Tin, for its part, makes it possible to lower the brazing temperature, but has the defect of rendering ductile soldering (solder), which is not desired. This is why the proportion tin must remain low. Advantageously, a quaternary compound Ag-Cu-Zn-Sn can be used. According to an exemplary embodiment, the compound is quaternary and contains 56% silver, 22% copper, 17% zinc and 5% tin, with a melting point of about 650 ° C. The solder does not contain cadmium, despite the known property of this component of lowering brazing temperatures, because of its potential harmfulness to the environment.

The metallurgical bond obtained ensures excellent electrical conduction. She does not increase the mass of the moving equipment, so that the kinetic energy to dissipate at the end of the opening or closing run remains relatively low. Brazing once the junction is not sensitive to temperatures of the order of 100 ° C at which it is subjected during the passage of the current, so that it does not deteriorate in the time under the influence of temperature.

Advantageously, the projecting portion of the rod comprises an axis, limited on the side of the ampoule by a shoulder, a part of the filler compound constituting a seal interface interposing axially between the shoulder and an axial rim of the bore, and another part of the feed compound constituting a radial interface seal between the bore and the axis. A junction having an excellent mechanical strength is thus obtained. The axis constitutes a free end of the rod, so that the assembly operation is particularly simple. It suffices to insert successively on the axis a washer of solder, then the bore of the connection, before carrying out the soldering operation.

Advantageously, the axis is circular in section, and the bore, so that the seal The radial interface between the bore and the axis conforms to a cylindrical shape, which makes it possible to to overcome the constraints of radial positioning of the connection relative to the axis.

According to one embodiment, the welding is performed by bombardment welding electronic or by electronic diffusion, without the addition of metal.

Advantageously, the flexible connection comprises a second rigid end portion, constituting a connection pad provided with connecting means to the busbar, the flexible portion being located between the first and second rigid portions. The link hose then simultaneously ensures the function of flexible connection and that of beach connection for a busbar. It is possible to provide bores, tapped or no, for fixing to the busbar.

In this case, it is particularly advantageous to provide that the flexible connection is formed by a stack of metal blades, assembled to each other by welding at said first and second rigid end portions, the blades remaining independent of each other in the flexible part of the link.

• la figure 1 représente une vue en perspective d'un appareillage selon l'invention, comportant une ampoule à vide installée dans un bâti support ;
• la figure 2 représente une vue en coupe axiale de l'appareillage de la figure 1 ;
• la figure 3 représente une liaison électrique souple permettant une liaison électrique entre l'ampoule et une plage de raccordement ;
• la figure 4 représente une vue éclatée d'une partie de l'appareillage avant son assemblage ;
• la figure 5 représente schématiquement une opération de brasage réalisant une jonction entre une tige de l'ampoule et la liaison électrique flexible.

Other advantages and features will emerge more clearly from the following description of a particular embodiment of the invention, given by way of non-limiting example, and represented in the accompanying drawings in which:

• Figure 1 shows a perspective view of an apparatus according to the invention, comprising a vacuum bulb installed in a support frame;
• Figure 2 shows an axial sectional view of the apparatus of Figure 1;
• Figure 3 shows a flexible electrical connection for an electrical connection between the bulb and a connection pad;
• Figure 4 shows an exploded view of part of the equipment before assembly;
• Figure 5 schematically shows a brazing operation providing a junction between a rod of the bulb and the flexible electrical connection.

With reference to FIGS. 1 and 2, a switchgear device comprises a vacuum interrupter 10 supported by a frame 12 and driven by a mechanism 13 of conventional type. Two connection pads 14 and 16, fixed to the frame 12, are intended to connect electrically the apparatus to a busbar (not shown).

Here, the generic expression of vacuum bottle designates a set of known type, having a cylindrical body 17 forming an enclosure 18 where there is a relative vacuum and which encloses a pair of separable contacts 22, 24. The body 17 is itself divided into a intermediate insulator section 19 made of insulating material, a first end section 20 a first flange closure, and a second section metal end 21 constituting a second closure flange. One of the contacts is a pellet 22 brazed at the end of a conducting cylinder 26 and constitutes with this cylinder cylinder a fixed contact member 28. The cylinder 26 passes through the second flange 21 and is soldered to it. The cylinder 26 is also welded to a rigid metal coil 29, it is welded to the connection pad 14. Thus an electrical connection is ensured between the fixed contact member 28 and the connection pad 14, via the turn 29. The turn 29 is intended to induce, in the separation zone of the contacts 22, 24, a magnetic field conducive to cutting an incipient electric arc between contacts during their separation. Screws secure the turn 29 to the frame 12, and thus the rigid attachment between the cylinder 26, itself secured to the body 17 of the bulb, and the frame 12. Moreover, and as will be explained later in detail, the first flange 20 is positioned and maintained with respect to the frame 12 via a fastening collar 100 retained in a groove 130 of the frame.

The contact 24 is a pad brazed at the end of a movable contact member 30 whose body is constituted by a metal conductive rod 32, in this case a rod of copper, passing through an orifice of the first flange 20. This rod 32 extends outside of the enclosure, as can be seen more clearly in FIG. small diameter, thus defining an intermediate shoulder 38. The end of the stem is equipped with an axial threaded hole 39. A sealing bellows 40 brazed on the rod 32 and on the internal wall of the first end section, allows an axial translation movement of the movable member 30 relative to the fixed contact member 28, while preserving the vacuum prevailing in the enclosure 18.

The rod 32 is connected to a lever 80 with two parallel arms 81, 82, via a insulating arm 42. The insulating arm 42 comprises a plastic body 43 overmoulding on the one hand the head of a first threaded rod 44, and secondly the head of a second rod threaded 45 located in the axial extension of the first. The first threaded rod 44 is screwed into the threaded blind hole 39 located at the end of the rod 32 of the bulb. On the second threaded rod 45 is screwed a tubular adjusting nut 46. The nut supports a end a support plate 47 for the end of a contact pressure spring 48. The other end of the spring 48 bears on a second plate 49, which rests on a 83. The bar 83 has a bore 84 forming a crossed guide sleeve by the tubular nut 46. The bar 83 freely journalled in lateral axes 85 supported by the arms 81, 82 of the lever 80. The guide sleeve 84 allows both the translation of the nut 46 parallel to its axis and its free rotation. Nut 46 features a shoulder that comes to rest on the part of the bar 83 opposite to the second plate 49. The two arms 81, 82 of the lever 80 pivot about an axis 86 supported by the frame 12 and are operated jointly at their free end by a closing mechanism and opening (not shown), this mechanism being intended to drive the contact member mobile 30 between a position of contact with the fixed contact member 28 and a position of separation. At the opening, the lever 80 pivots in the opposite direction of the hands of a shows around the axis 86 in Figure 2, directly driving the bar 83, the nut 46, the arm 42 and the movable contact member 30. At closure, the lever 80 pivots in the direction clockwise around the axis 86, driving the bar 83 which compresses the spring 48 via the plate 49. The closing force is then transmitted by the spring 48 to the movable contact 30, via a transmission chain comprising the plate 47, the nut 46 and the insulating arm 42.

The electrical connection of the rod 32 to the busbar is ensured by means of a connection flexible electrical connector 50, shown schematically in FIG. end 56 is the connecting pad 16, while the other end 58 is soldered to the body of the rod 32. The flexible link 50 is constituted by a stack of metal blades 52, in this case copper blades. Each metal blade 52 has a curved medial portion 54 extended at each end by one of the parts end plates 56, 58. The blades 52 have different lengths and shapes, together to form a stack having the desired curved shape at the level of the middle part 54. At the ends 56, 58, the blades 52 are welded together. to others by a process of atomic diffusion welding, without the addition of material, so that each end constitutes a rigid one-piece part. In their middle part 54, the blades 52 remain separated from each other, which gives a good flexibility overall to the electrical connection 50 thus formed. As illustrated in Figure 4, the part end 56 constituting the connection pad has fixing means 60, in this case tapped holes opening, allowing its attachment to the frame of the apparatus, and connection means 62, in this case other threaded holes, allowing its connection to a busbar. The other end portion 58 has a bore 64 corresponding to the diameter of the shaft axis 36.

The collar 100, visible in detail in FIG. 4, is made of plastic material, the occurrence a polyamide 6-6, and comprises two parts 101, 102 hinged together by a hinge 103, so as to take an open mounting position shown in FIG. 4, as well as a closed position shown in FIG. which elastic hooks 104 come to staple in lights 106 corresponding. The closed collar forms a flange having a flat bottom 107 and a wall cylindrical device 108, for fitting therein the end of the first flange 20 of the bulb 10. The central part of the flat bottom has a light 120 allowing the passage of the rod 32 of the bulb. This light, of cylindrical general shape, ensures the guidance of the rod 32. The collar 100 is provided with two main lateral rails 109, connected to the flat bottom 107 by two lateral lugs 110, and two auxiliary lateral rails 112 connected to the flat bottom 107 by two other lateral lugs 114. Each auxiliary rail 112 is in the extension of one of the main rails 109. Each main rail 109 forms in a front part a stop 116 in recess, and in a part rear elastic clip 118.

The insulating portion 19 of the body 17 of the bulb is covered with an insulating sleeve 90 (FIG. 2) provided with fins intended to lengthen the creepage distance between the metal parts switched on the equipment. The sleeve 90 widens in its upper part and forms a lip 92 which covers part of the turn 29, so as to lengthen the distance between the metal parts under tension. An intermediate bead 94, the inner surface of which is covered with a semi-conductive paint, helps smooth the lines of field at vicinity of the edges of the turn 29.

The plastic body 43 of the insulating arm 42 forms a cylindrical skirt which protects the spring 48 and the threaded rod 45 and which thus ensures the electrical insulation between the rod 32 and the flexible connection 50 on the one hand, and the mechanism on the other hand.

The mounting of the bulb 10 in the frame 12 is as follows. In first step, the cylinder 26 is welded to the subassembly formed by the turn 29 and the The insulating sleeve 90 is then force-fitted onto the body 17 of the bulb and on the turn 29.

The bulb 10 must then be equipped with its electrical connection 50. The axis 36 of the rod 32 is inserted into the bore 64, with the interposition of a metal compound washer 68, according to the exploded diagram of FIG. have a relatively low melting temperature, preferably less than 700 ° C, of so as not to damage the internal solders of the bulb. In this case, it is in this example a compound of 56% silver, 22% copper, 17% zinc and 5% tin, whose melting point is of the order of 650 ° C. We bring a source of heat 70, shown schematically in FIG. 5, at the free end of the bore, up to obtain fusion of the washer 68 and capillary axial infiltration of a part of the compound metallic filler in the cylindrical space at the interface between the bore and the axis. Of well known manner of the brazing specialist, the initial game between the pieces, namely between the bore and the axis, must be chosen in a suitable way on the one hand to brazing, wetting the surfaces to be assembled, and secondly to ensure the resistance mechanics of the brazed joint under the later conditions of use. The brazed joint 72 obtained reveals on the one hand a cylindrical interface zone 74 between the axis and the bore, and on the other hand an annular interface area 76 between the upper edge of the bore 64 and the shoulder 38 of the rod.

This assembly being performed, the rod 32 is inserted radially into the collar 100 open, then the collar 100 is closed so as to circle the end of the first flange 20 of the body 17 of the bulb and the rod 32, the elastic hooks 104 coming from staple in corresponding lights 106. The assembly thus constituted is then introduced laterally into the frame 12, the rails 109 being introduced into the grooves 130, and forming with the latter a slide guide. The necklace then forms a slide that slides in the grooves 130 until the stops 116 meet with corresponding surfaces of the frame, the staples 118 then coming to close on surfaces corresponding support 132 of the frame.

It then remains to screw to the frame 12 the connection pads 14, 16 and the turn 29, to screw the insulating arm into the threaded hole in the stem and adjust the contact pressure using of the adjusting nut.

In all rigor, the movement printed at the rod 32 of the bulb 10 by the lever 80 the absence of play between the moving parts would not be perfectly rectilinear compared to the 12. However, the angle between the lever 80 and the rod 32 is always very close to the angle right, and the stroke of the rod 32 of the bulb between its open position and its position of closing does not exceed a few millimeters, which corresponds to an angle of rotation of the lever 80 not exceeding a few degrees, so that in the absence of play, the deflection radial rod 32 would be of the order of one hundredth of its axial stroke. In the mode of realization described, this deflection is absorbed by the existing games between the various elements of the kinematic chain, in particular at the level of the pins 85 and the axis 86. However, if we wanted a bigger race, it would be possible to guide the bar 126 in an oblong of the lever 90, 92, 94.

The subset thus formed forms a module that can be mounted and tried in the factory, before storing it independently of the mechanism 13. The final assembly of the equipment may be deferred. The modules make it possible to constitute apparatus differing from each other by the number of poles arranged side by side.

Naturally, various modifications are possible.

The section of the stem and the corresponding section of the bore are not necessarily circular. The stack of blades can be made with the interposition of washers spacing at either end as described in the document US 5 5 30 216. The ampoule may have two movable contact members, rather than an organ movable contact and a fixed contact member. The internal structure of the bulb can be different from that described. The guide of the rod relative to the bulb can be realized by any appropriate means. The apparatus can be of any type implementing Vacuum bulbs, in particular, switch, circuit breaker, with or without function of sectioning.

Claims (11)

1. Electrical switchgear apparatus designed to be electrically connected to a busbar and comprising:

   a vacuum cartridge (10) comprising a body (17) forming an enclosure (18) housing a pair of separable contacts (22, 24), one (24) of said contacts being fixedly secured to a metal rod (32) movable in translation, a part of the rod (32) being salient from the enclosure (18) of the cartridge;

   a flexible metallic electrical connector (50) designed to electrically connect the rod (32) to the busbar, the flexible connector (50) being formed by a stack of metal blades (52) and comprising a first rigid end part (58) defining a bored hole (64) wherein the salient part of the rod (32) is inserted;

   characterized in that :

   the metal blades (52) are assembled to one another by welding at the level of said first rigid end part (58) so as to form a monoblock assembly at this level,

   the flexible electrical connector (50) is fixed to the salient part of the rod (32) by means of a braze (72) between the salient part of the rod (32) and the first rigid end part (58).
2. Switchgear apparatus according to claim 1, characterized in that it comprises a sealing bellows (40) brazed on the one hand onto a wall of the body (17) of the cartridge and on the other hand onto the rod (32), the joining braze (72) fixing the flexible electrical connector and the salient part of the rod implementing a metallic filler compound having a melting temperature lower than the melting temperature of the braze fixing the rod to the sealing bellows.
3. Switchgear apparatus according to either one of the foregoing claims, characterized in that the metallic filler compound has a melting temperature appreciably lower than 900°C, and preferably lower than 700°C.
4. Switchgear apparatus according to claim 3, characterized in that the metallic filler compound is a silver-based compound in proportions of more than 30%, with a tin content in proportions of less than 10%.
5. Switchgear apparatus according to claim 4, characterized in that the metallic filler compound is a silver-based compound in proportions of more than 50%, with a tin content in proportions of less than 6%.
6. Switchgear apparatus according to claim 5, characterized in that the metallic filler compound is a quaternary silver-copper-zinc-tin compound.
7. Switchgear apparatus according to any one of the foregoing claims, characterized in that the salient part of the rod (32) comprises a spindle (36), limited on the cartridge side by a shoulder (38), a part of the filler compound forming an interface joint (76) interposed axially between the shoulder and an axial edge of the bored hole, and another part of the filler compound forming a radial interface seal (74) between the bored hole (64) and the spindle (36).
8. Switchgear apparatus according to claim 7, characterized in that the spindle (36) is of circular cross-section, as is the bored hole (64), so that the radial interface seal (74) between the bored hole (64) and the spindle (36) follows a cylindrical shape.
9. Switchgear apparatus according to any one of the foregoing claims, characterized in that the metal blades (52) are assembled to one another by electron bombardment welding or by electron scattering welding, without any additional material.
10. Switchgear apparatus according to any one of the foregoing claims, characterized in that the flexible connector (50) comprises a second rigid end part (56), forming a connecting strip (16) equipped with means (60) for connection to the busbar, the first (58) and second (56) rigid end parts being joined by a flexible part (54) of the flexible connector (50).
11. Switchgear apparatus according to claim 10, characterized in that the metal blades (52) forming the flexible connector (50) are assembled to one another by welding at the level of the second rigid end part (56) and remain independent from one another in the flexible part (54) of the connector (50).

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