Title of Invention

ALUMINIUM CONNECTION FOR AN ELECTRICAL APPARATUS IN PARTICULAR A FUSE

Abstract

A connection grip comprises two contact elements 14, 16 formed by aluminum strips each comprising: -a convex contact surface 22 arranged in the internal mid-part between the fixing base 36 for fixing to the rear part and a protruding stud 26,27 acting as discharger, -a cap 28 made of insulating material covering the front part above the stud 26, 27 to from a high-speed making means at the input of the grip 10, -and heat dissipation fins 30 arranged over the external surface opposite the stud. Application: connection of fuse with terminal in the from of a knife-blade.

Full Text

BACKGROUIND 0F 1HE INVENTION The invention relates to a connection grip for a terminal of an electrical apparatus, comprising: - at least two symmetrical contact elements designed to be engaged by plugging onto said terminal, and having main contacts for flow of the rated current and arcing contacts acting as discharger contact fingers, - and flexible means for applying a contact pressure on the terminal. STATE OF THE TECHNIQUE Grips commonly used for connection of high-rating fuses, notably for current intensities of about 400 A, are made from a copper sheet cut and folded to form a first gripping finger equipped with main contacts for flow of the rated current, and a second gripping finger equipped with arcing contacts. The two gripping fingers are joined to a U-shaped common base and the contact pressure is achieved by circular springs in the form of circlips acting on the flexible branches of the first gripping finger. The manufacturing cost of such connection grips is relatively high and the heat absorption due to flow of the current remains very limited. OBJECT OF THE INVENTION The object of the invention is to achieve a connection grip for a high-rating electrical apparatus, having an optimum heat dissipation and a low manufacturing cost. The connection grip according to the invention is characterized in that the two contact elements are formed by aluminium strips, each comprising: a convex contact surface arranged in the internal middle part between the fixing base for fixing to the rear part, and a protruding stud acting as discharger, - a cap made of insulating material covering the front part above the stud to form a means for high-speed making at the input of the grip, and heat dissipation fins arranged on the external surface opposite the stud. According to a preferred embodiment, the intemal face of the cap is inclined with respect to the longitudinal direction so as to constitute a convergent with the cap of the other contact element. Each contact element has a rectangular cross section and comprises a groove situated on the external surface between the fins and the fixing base for securing a double spring. The contact surface is advantageously provided with serrations to foster electrical contact with the terminal in the form of a knife-blade. One of the studs is made of copper or copper alloy whereas the other stud is made of insulating material so as to displace the arcing zone to the first stud acting as arcing contact. According to one feature of the invention, the fixing base of each contact element is curved with respect to the flat strip of the feeder conductor to allow movements of thes elements towards and away from one another in the engagement and disengagement phases of the terminal. According to another feature of the invention, the two contact elements are provided with stops arranged under the contact surfaces and coming into engagement with one another to define the bounds of a first transverse gap between the studs. Depending on the rating and the heat rise tolerated, each contact element is divided into at least two adjacent parts separated from one another by a second gap extending perpendicularly to the first gap so as to constitute a gripping finger with multiple contacts. BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and features of the invention will become more clearly apparent from the following description of an embodiment of the invention given as a non-restrictive example only and represented in the accompanying drawings in which: - figure 1 is a schematic perspective view of a connection grip according to the invention; - figure 2 shows an exploded perspective view of an assembly formed by a grip and a feeder conductor before plug-in engagement of the fuse; - figure 3 is an identical view to figure 2 after plug-in engagement of the fuse; - figure 4 represents an elevational view of the grip according to figure 1; - figure 5 shows a perspective view of another grip with multiple contacts; - figure 6 is a side view of figure 5. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT With reference to figures 1 to 4, a connection grip 10 of a high-rating fiise 12 is formed by two elongate contact elements 14, 16, arranged facing one another in symmetry with respect to the longitudinal mid-plane. The rear ends of the two contact elements 14, 16 are securedly affixed to a fixing strip 18 for fixing a feeder conductor 20. The contact elements 14, 16 present identical structures formed by aluminium strips, advantageously achieved by extrusion, and being subjected to a nickel- or silver-based surface treatment. Each contact element 14, 16 of rectangular cross-section comprises an appreciably convex, serrated contact surface located in the internal mid-part between a stop 24, 25 and a stud 26, 27, the latter forming a discharger for the left-hand contact element 14 and a back-discharger for the right-hand contact element 16. The fi"ont terminal part above the stud 16 is covered by a cap 28 made of insulating material, for example polyamide-based, acting as high-speed making means at the input of the connection grip. The internal faces of the two caps 28 are inclined with respect to the longitudinal direction so as to constitute a convergent at the input of the connection grip 10. The serrations on the contact surface 22 foster electrical contact and reduce the insertion and extraction effort of the terminal 29 in the form of a knife-blade of the fuse 12. The convex shape of the two contact surfaces 22 enable any alignment fault of the terminal 29 with respect to the grip 10 to be absorbed. The external side face of each contact element 14, 16 is provided with a series of heat dissipation fins 30 extending opposite the stud 26, 27 between the cap 28 and a groove 32 in which the end strands of the two contact pressure springs 34 are housed end to end. Each spring is in the form of a U extended by two end pieces folded to form a bracket. The presence of this double spring guarantees a uniform distribution of the contact pressure of the grip 10 on the terminal 29 in the inserted position. The rear part of each contact element 14, 16 is provided with an appreciably curved base 36 and equipped with a drilled hole in which at least one screw 38 is screwed enabling the contact elements 14, 16 to be fitted on the fixing strip 18 of the conductor 20. A compression spring 40 is interposed between the strip 18 and the head of each screw 38 so as to allow a slight separation movement of the contact elements 14, 16 when the terminal 29 is inserted or removed. The respective stops 24, 25 coming into engagement prevents the contact elements 14, 16 from moving towards one another on input of the grip 10 and permanently maintains a transverse gap 42 between the studs 26, 27. The stud 26 constituting the discharger on the left-hand contact element 14 is made of copper or of tellurium copper alloy designed to prevent welding from starting. The other stud 27 constituting the back-discharger of the second contact element 16 is advantageously made of insulating material, for example polyamide, so as to permanently displace the arcing zone onto the stud 26 which acts as arcing contact. It is clear that the stud 27 could also be conducting like the stud 26. Operation of the connection grip 10 according to figures 1 to 4 is as follows: In the disengaged position of the grip 10 illustrated in figures 1 to 4, the distance between the studs 26, 27 is smaller than the thickness of the terminal 29 and than the gap arranged between the two contact surfaces 22. The double spring 34 and the coming into engagement of the stops 24, 25 keep the two contact surfaces 22 appreciably parallel to one another and perpendicular to the fixing strip 18. The studs 26, 27 remain permanently protruding out with respect to the convergent of the caps 28. In the engaged position (figure 3), the terminal 29 of the fuse 12 is inserted between the two contact surfaces 22 and the double spring 34 assures a uniform distribution of the contact pressure. The mechanical reaction generated in the insertion phase of the terminal 29 causes a slight separation movement of the contact elements 14, 16 following pivoting of the bases 36 in the opposite direction on the fixing strip 18 of the conductor 20. The current of the fuse 12 is divided into two in the contact elements 14, 16, and the corresponding Joule effect is removed by the heat dissipation fins 30. The presence of the insulating caps 28 at the input of the grip 10 enables high-speed making while live, the arc occurring only between the stud 26 and the terminal 29 without migrating onto the aluminium contact elements 14, 16. When plug-out is performed notably to replace a defective fuse, removing the terminal 29 in the direction of the arrow F (figure 3) causes the contact surfaces 22 to move towards one another as soon as the terminal 29 leaves the studs 26, 27. If the operation is performed live, the arc is established only on the stud 26 acting as arcing contact. Figures 5 and 6 show a grip 100 with multiple contacts in which each contact element 114, 116 is divided into two adjacent parts 114a, 114b; 116a, 116b, separated from one another by a gap 142 extending perpendicularly to the gap 42. It is clear that the contact elements 114, 116 could be subdivided into three or four equal parts depending on the rating of the apparatus and the maximum heat rise tolerated. CLAIMS 1. A connection grip for a terminal (29) of an electrical apparatus, comprising: - at least two symmetrical contact elements (14, 16; 114, 116) designed to be engaged by plugging onto said terminal, and having main contacts for flow of the rated current and arcing contacts acting as discharger contact fingers, - and flexible means for applying a contact pressure on the terminal (29), characterized in that the two contact elements (14, 16; 114, 116) are formed by aluminium strips, each comprising: - a convex contact surface (22) arranged in the internal middle part between the fixing base (36) for fixing to the rear part, and a protruding stud (26, 27) acting as discharger, - a cap (28) made of insulating material covering the front part above the stud (26, 27) to form a means for high-speed making at the input of the grip (10, 100), and heat dissipation fins (30) arranged on the external surface opposite the stud (26, 27). 2. The connection grip according to claim 1, characterized in that the internal face of the cap (28) is inclined with respect to the longitudinal direction so as to constitute a convergent with the cap of the other contact element. 3. The connection grip according to claim 1, characterized in that each contact element (14, 16; 114, 116) has a rectangular cross section and comprises a groove (32) situated on the external surface between the fins (30) and the fixing base (36) for securing a double spring (34). 4. The connection grip according to claim 1, characterized in that the contact surface (22) is provided with serrations to foster electrical contact with the terminal (29) in the form of a knife-blade. 5. The connection grip according to claim 1, characterized in that the fixing base (36) of each contact element (14, 16; 114, 116) is curved with respect to the flat strip (18) of the feeder conductor (20) to allow movements of these elements towards and away from one another in the engagement and disengagement phases of the terminal (29). 6. The connection grip according to claim 5, characterized in that the two contact elements (14, 16; 114, 116) are provided with stops (24, 25) arranged under the contact surfaces (22) and coming into engagement with one another to define the bounds of a first transverse gap (42) between the studs (26, 27). 7. The connection grip according to claim 5 or 6, characterized in that the curved base (36) is secured to the fixing strip (18) by means of screws (38) with interposed compression springs (40) allowing a slight pivoting movement of the two contact elements (14, 16;114, 116) when engagement or disengagement take place. 8. The connection grip according to any one of the foregoing claims, characterized in that one of the studs (26) is made of copper or copper alloy, whereas the other stud (27) is made of insulating material; so as to displace the arcing zone onto the first stud (26) acting as arcing contact. 9. The connection grip according to claim 3, characterized in that the double spring (34) comprises two U-shaped springs each having two end pieces folded to form a bracket. 10. The connection grip according to any one of the foregoing claims, characterized in that each contact element (114, 116) is divided into at least two adjacent parts (114a, 114b; 116a, 116b) separated from one another by a second gap (142) extending perpendicularly to the first gap (42). 11. A connection grip for a terminal substantially as herein described with reference to the accompanying drawings.

Documents:

761-mas-2000-abstract.pdf

761-mas-2000-claims filed.pdf

761-mas-2000-claims granted.pdf

761-mas-2000-correspondnece-others.pdf

761-mas-2000-correspondnece-po.pdf

761-mas-2000-description(complete) filed.pdf

761-mas-2000-description(complete) granted.pdf

761-mas-2000-drawings.pdf

761-mas-2000-form 1.pdf

761-mas-2000-form 26.pdf

761-mas-2000-form 3.pdf

761-mas-2000-form 5.pdf

761-mas-2000-other documents.pdf

abs-761-mas-2000.jpg