Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
  • H01H85/02—Details
  • H01H85/04—Fuses, i.e. expendable parts of the protective device, e.g. cartridges
  • H01H85/041—Fuses, i.e. expendable parts of the protective device, e.g. cartridges characterised by the type
  • H01H85/0411—Miniature fuses
  • H01H85/0415—Miniature fuses cartridge type
  • H01H85/0417—Miniature fuses cartridge type with parallel side contacts
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
  • H01H85/02—Details
  • H01H85/04—Fuses, i.e. expendable parts of the protective device, e.g. cartridges
  • H01H85/05—Component parts thereof
  • H01H85/055—Fusible members
  • H01H85/08—Fusible members characterised by the shape or form of the fusible member
  • H01H85/11—Fusible members characterised by the shape or form of the fusible member with applied local area of a metal which, on melting, forms a eutectic with the main material of the fusible member, i.e. M-effect devices
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
  • H01H85/02—Details
  • H01H85/04—Fuses, i.e. expendable parts of the protective device, e.g. cartridges
  • H01H85/05—Component parts thereof
  • H01H85/055—Fusible members
  • H01H85/12—Two or more separate fusible members in parallel

Definitions

• the present invention relates to a flat fuse for nominal currents greater than or equal to 20 Amps, and more particularly to a flat fuse for cars.
• Such fuses generally include a housing or insulating body in which is partially mounted a conductive member constituted by two pluggable flat connection tabs, and joined by a fusible or calibrating part.
• the fusible part can bend and come into contact with one of the internal faces of the insulating body or case.
• the material used for the housing is a plastic material, it follows that bringing the fusible part into contact is likely to melt the plastic material and would cause complete deterioration of the housing.
• the phenomenon of deflection generally occurs at the center of the calibrating part because, it is there that the hottest point is located when the temperature curve is plotted.
• the length, width and thickness of the fuse part are not the same for a 40 amp flat fuse and a 60 amp flat fuse, which is a serious drawback for mass production. .
• a flat fuse comprising a fuse part produced in one piece with the connection tabs, but which is partially hollowed out in the central part so as to produce a thinned zone d 'thickness and constant section, only the thinned zone constituting a calibrating zone.
• the calibrating part of the fusible part comprises cutouts intended to provide cooling zones capable of generating a delaying effect on the deflection. seed of said calibrating part.
• the present invention aims to remedy the aforementioned drawbacks and to provide a flat fuse comprising a flat fuse part and flat connection tabs in which the temperature communicated to the connection tabs is reduced before blowing.
• the present invention relates to a flat fuse, of the type comprising a housing in which is housed in part a conductive member provided with two flat connection tabs, the free ends of which are located outside the housing, said connection tabs being connected to the inside the housing by a flat fusible part on one face of which a drop of metal is deposited, and which is characterized in that the fusible part comprises a central calibrating zone of width smaller than the width of the adjacent lateral zones of connection with the connection tabs, the contact surface of said drop being at least greater than half the surface of the calibrating zone.
• An advantage of the present invention is to allow the drop of metal to extend over almost the entire calibrating zone without risk of contact with the connection tabs.
• Another advantage of the present invention lies in the fact that the calibrating part has a reduced length and a possibility of constant thickness whatever the nominal current or rating of the flat fuse.
• the fuse part comprising two calibrated zones in parallel mounted, of which at least one of said zones is provided, approximately, in the center of at least one drop of metal .
• FIG. 1 is a plan view of the flat fuse comprising a protective box in which the conductive member shown in FIG. 2 is arranged,
• FIG. 2 is a plan view of the conductive member according to an embodiment of the invention.
• FIG. 3 is an enlarged sectional view along III-III of FIG. 2,
• FIG. 4 is an enlarged sectional view along IV-IV of FIG. 2,
• FIG. 5 is a partial top view of the grading zone shown in FIG. 2, with blades folded over the drop of metal,
• FIG. 6 is an elevation view of the trapezium-shaped expansion limiting blades
• FIG. 7 is a plan view of the conductive member according to a second embodiment according to the invention.
• the box 1 shown in Figure 1 can be of the one-piece type or in two parts, the front part or cover 2 being mounted by crimping or other means on the rear part or body-support 3, for example as described in FR- A-87 04 382.
• a conductive member 4 according to the invention, shown in FIG. 2, is mounted in the housing 1.
• the member or conductive element comprises two connection tabs 5 and 6, the ends 7 of which are bevelled to allow easy insertion into corresponding housings provided in various receiver assemblies such as interconnection boxes.
• a fuse part 8 is mounted between the connection tabs 5 and 6 and it is connected to the internal sides 5a, 6a of the latter.
• the fusible part 8 is for the same rating, of constant thickness and it is constituted by at least one central calibrating zone 9 made of zinc alloy (approximately 99.7% of zinc), arranged between two lateral zones 10 and 11 intended to be connected to the connection tabs 5 and 6 respectively.
• Calibrating the central area 9 has a width W smaller than the width 1 2 of the adjacent zones 10,11 so as to provide flanges 12, while the length La.
• Of the calibrating zone is less than or equal to two thirds of the length L_ > of the fuse part (fig. 4).
• the drop 13 is in contact on the calibrating zone 9 along a contact surface S which is at less than half of the surface S a , of the face of the calibrating zone receiving said drop.
• the contact surface Sx is substantially equal to that S_. of the calibrating zone.
• the limiting means are constituted by at least one blade of low height, and preferably by two blades 14 and 15 which are each connected to a longitudinal side 16, 17 of the calibrating zone 9, and in a plane perpendicular to the plane containing said calibrating zone (fig. 4).
• each blade 14, 15 has a rounded profile and it is provided substantially at equal distance from the internal edges of the connection zones (18) formed on the connection tabs 5, 6.
• the fuse part 8 is electrically welded. or on the dial on the underside of the connection tabs 5, 6 when the plan view of FIG. 2 is considered, and it preferably, but not necessarily, has a small thickness so that a housing 20 for the drop 13 is formed between the calibrating zone 9 and the internal edges 18 of the connection tabs 5,6.
• each connection zone 10, 11 comprised between the rim 12 and the corresponding welding zone 22 also constitutes an additional heat dissipation zone which will be discussed later.
• drop of metal is meant a very small mass of metal which can have any regular shape or not, such as spherical, parallelepipedic.
• the metal drop is joined to the calibrating zone by fusion or any other suitable means.
• each blade 14, 15 whose height is substantially equal to or greater than the corresponding dimension of the drop 13, has an upper free part 23, 24 which is foldable over the drop 13 so as to further trap said drop, the expansion is limited both upwards because of the parts 23, 24, after folding, and laterally because of the blades.
• the drop 13 when it is traversed by a strong electric current which produces a fusion of said drop 13, is forced to conform to the shape of the blades 14, 15 and can only spread towards the edges 12
• the drop 13 takes the form shown in FIG. 5, that is to say that it presents at its ends a sort of meniscus 25.
• the blades 14 and 15 present tent a trapezoid shape whose upper free edge 40 is substantially straight with rounded ends 41 and 42 rounded.
• connection tabs 5,6 On each side of each central part 26,27 of the connection tabs 5,6 to which a lateral zone 10,11 of the fuse part 8 is connected, there are provided heat dissipation fins 28,29 which are separated from the middle part 26, 27 by two notches 30, 31, the role of which is to delimit the ailet ⁇ 28, 29 for cooling the connection tabs 5, 6 and the four fixing points of said connection tabs on the housing 1, shown in figure 1.
• connection tabs 5,6 each have two orifices 32,33 for their mounting by crimping on pins provided for this purpose in the support body 3 of the protective housing 1.
• connection tab 5,6 comprises, on the external side 5b, 6c, opposite the internal side 5a, 6a, a cutout or notch 34,35, intended to allow during continuous production, in the form of a strip, to accommodate the conductive member 4 in the housing 1.
• the alloy of the drop 13 is in a solid state and the temperature in the calibrating zone is lower than the eutectic point of the alloy.
• the drop 13 goes to the liquid state while remaining centered on the hot point, but the alloy of which it is made diffuses into the material of the calibrating zone 9 in zinc. Temperature of fusion of the calibrating zone 9 is located between that of the alloy of the drop 13 and that of the zinc. In this way, the temperature communicated to the connection tabs 5, 6 is reduced during very slow fusion, the reduced length of the calibrating zone eliminating any risk of contact with the housing 1 for said low overload.
• the melting time of drop 13 is relatively short, of the order of a few seconds, and the molten alloy of said drop does not have time to diffuse in the zinc of the calibrating zone.
• the melting temperature is close to that of zinc because the rupture takes place essentially on the thickness of zinc.
• the heat dissipation fins 28 and 29 of the connection tabs 5 and 6 receive an imprint 22a during the passage of the welding wheel between the fuse part 8 and said connection tabs and, more precisely, between the parts 10, 11 of the fuse part and said connection tabs.
• the fusible part comprises two cali ⁇ brantes zones 9a and 9b which are mounted in parallel but located in the same horizontal plane , slightly lower laughing at that containing the connection tabs 5,6; each calibrating zone 9a, 9b having the dimensional characteristics of the calibrating zone 9 as defined above.
• a drop of metal 13a is deposited on at least one of the calibrating zones 9a or 9b and, if necessary, on each calibrating zone, as shown in FIG. 7.
• one or both calibrating zones 9a, 9b are provided expansion limiting blades shown in one of Figures 2 to 7.
• the droplet (s) 13a are made of tin-silver alloy.
• the calibrating zones 9a, 9b are not tinned on both sides and have a thickness of approximately 0.30 mm.
• As the calibrating zones 9a, 9b are made of zinc alloy (about 99.7% zinc), such a thickness is best suited for the formation of the tin-silver / zinc alloy.
• the metal drops 13a come either from a welding wire with incorporated flux flux, or from a pre-dimensioned element, in the form of a piece as shown in FIGS. 2 to 6.
• one of the calibrating zones 9a, 9b or both can or can include the expansion limiting means 14, 15 described with reference to FIGS. 2 to 6.
• connection tabs 5, 6 then in the fuse part 8 creates, in the center of each calibrating zone 9a and 9b, a hot spot.
• the drops of metal 13Aa are in a solid state because the temperature of the hot spots is less than approximately 221 ⁇ C.
• the metal drops 13a pass to a liquid state, the temperature at the hot spots then being above 221 * C, and below the melting temperature of the calibrating part 9a without drop. Therefore, the temperature communicated to the connection tabs 5 and 6 is reduced and the thermal resistance of the housing 3 is achieved and the risk of contact of the calibrating zones 9a, 9b with the walls of the housing is avoided.
• the calibrating zones are deformed due to a rise in temperature, the rupture of one of them causes the instantaneous rupture or breakdown of the other, the cutting of the calibrating zones being able to intervene either on the right or on the left of the solder drop.
• the metal drops 13a delay the rise in temperature of the hot spots and spread out randomly on one side or the other, or on both sides. other, hot spots.
• the breakdown time being short, around 10 seconds, the tin-silver / zintane alloy has no time to form.
• the calibrating zones 9a and 9b then cut in the vicinity of the hot spots, that is to say substantially at their center.
• the metal drops 13a do not have time to melt. This then results in a random sectioning of the calibrating zones, generally at the point where the section is the smallest.
• the various constituent elements of the fuse easily lend themselves to mass production in the form of strings so as to be able to be wound up in the form of coils.
• the elements of the housing are provided with lateral fasteners, not shown, which connect the supports together and the covers together.
• the electrical components i.e. the connection tabs and the cali- brante, are also produced in the form of chape ⁇ lets. The installation of the various constituent parts of the fuse can then be carried out very easily according to appropriate sequences, after which, the fuses terminated are separated by cutting the side connections.

Applications Claiming Priority (5)

Publications (1)

Family

ID=26228455

Family Applications (1)

Country Status (5)

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• 1992
  • 1992-01-13 CA CA002100782A patent/CA2100782A1/en not_active Abandoned
  • 1992-01-13 EP EP92904874A patent/EP0625284A1/de not_active Withdrawn
  • 1992-01-13 US US08/090,019 patent/US5373278A/en not_active Expired - Fee Related
  • 1992-01-13 JP JP4504997A patent/JPH06504875A/ja active Pending
  • 1992-01-13 WO PCT/FR1992/000021 patent/WO1992013356A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

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