WO1996027220A1

WO1996027220A1 - A method for connection of insulated conductors to a connection member

Info

Publication number: WO1996027220A1
Application number: PCT/SE1996/000188
Authority: WO
Inventors: Peter Stering
Original assignee: Asea Brown Boveri Ab
Priority date: 1995-03-02
Filing date: 1996-02-14
Publication date: 1996-09-06
Also published as: SE505286C2; SE9500762D0; AU4893496A; SE9500762L

Abstract

In a method for connection of a connection member (1, 4, 6), exhibiting a sleeve-shaped part (11, 4, 6), to a plurality of mutually insulated electric conductors (2a, 2b, 2c ...), in particular varnished conductors included in a stator winding for an asynchronous machine, all the conductors are inserted into the sleeve-shaped part of the connection member and are mechanically fixed thereto by pressing. Thereafter, by machining of the conductors and the sleeve-shaped part, a cut surface (S) is produced which cuts through all the conductors and part of the connection member, whereupon the cross section areas (2'a, 2'b, 2'c ...) of the conductors, by soldering on the cut surface, are electrically connected to each other and to the connection member.

Description

A method for connection of insulated conductors to a connection member

TECHNICAL FIELD

The present invention relates to a method for connection of a connection member to a plurality of mutually insulated electric conductors, in particular varnished conductors included in a stator winding for an asynchronous machine.

BACKGROUND ART

Windings for electric machines, in particular stator windings for asynchronous machines, are usually manufactured from con- ductors which are insulated with a varnish. During manufacture of such a winding, one work operation usually comprises connecting a connection member, such as a cable clip or a jointing sleeve, to a bundle of these conductors such that each one of the conductors becomes mechanically and electrically connected to the connection member. In the former case, the connection is performed with the bundle of conductors extended to the connection box of the machine, whereas in the latter case the conductor bundle is collected in the interior of the machine, whereupon a cable connected to the conductors is passed to the terminal box. The electrical connection of the conductor bundle to the cable clip is usually performed by first stripping the conductors mechanically, and then either contact-pressing them to the cable clip or soldering them thereto. The connection of the jointing sleeve is usually performed by first stripping the conductors mechanically, and then contact-pressing them to the jointing sleeve. Alterna¬ tively, the bundle of conductors, without preceding stripping, may be lashed to a cable, whereafter the end of the winding is heated to such a temperature that the insulating layer of varnish of the conductors is burnt away from part of the conductors, and finally the shell surfaces of the conductors are brought into mechanical and electrical connection with each other and with the cable by means of brazing. German patent specification DE-OS-33 16 563 Al describes connection of an insulated cable with a multi-wire conductor to a cable clip. The stripped conductor is inserted between two clamps formed on the cable clip and is attached mechanically to the cable clip via these clamps. The conductor has been stripped along such a long distance that a stripped part thereof projects outside the clamps and this projecting part is coated with a material capable of being soldered. By heating, the shell surface of the conductor is then brought into contact with the cross-section area of the clamps by means of the solderable material.

The Danish patent publication DK 126 350 describes connection of an insulated cable with a multi-wire conductor to a cable clip with a sleeve-shaped part via two concentrically arranged jointing sleeves, of which the outer one serves as insulation against the surroundings. The inner one of the jointing sleeves is mechanically fixed in the sleeve-shaped part of the cable clip such that the cross-section area thereof lies in a plane with the cross-section area of the sleeve-shaped part and the stripped conductor is inserted into the inner jointing sleeve such that also the cross-section area of the conductor is brought into the same plane. By welding, the cross-section area of the conductor is then oined mechanically and electrically to the cross-section areas on the inner jointing sleeve and the sleeve-shaped part of the cable clip.

In the first two methods described, stripping of the conductors constitutes one work operation, which is caused by the solderable material being applied to the shell surfaces of the conductors. Especially mechanical stripping of the conductors entails a difficult work operation from an ergonomic point of view. The last described method comprises as work operations, m addition to stripping of the conductors, also joining of two jointing sleeves to each other and to the cable clip. These work operations entail time expenditure and costs, which mani¬ fest themselves particularly in case of mass production such as, for example, serial manufacture of stator windings of varnished conductors for asynchronous machines . SUMMARY OF THE INVENTION

The object of the invention is to provide an improved method of the kind mentioned in the introduction, which ensures a reliable electrical connection between all the conductors and the connection member with a minimum of work operations.

What characterizes a device according to the invention will be clear from the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in greater detail by descrip¬ tion of embodiments with reference to the accompanying drawings, wherein

Figures 1A-1C show connection of a plurality of insulated con¬ ductors to a cable clip, viewed in a horizontal projection, according to one embodiment of the invention,

Figures 2A-2C show a section through the cable clip according to Figures 1A-1C,

Figures 3A-3B show connection of a plurality of insulated conductors to a cable clip, viewed in a horizon¬ tal projection, according to another embodiment of the invention,

Figures 4A-4B show a section through the cable clip according to Figures 3A-3B,

Figures 5A-5C show connection of a plurality of insulated con¬ ductors to a jointing sleeve, and

Figures 6A-6C show connection of a plurality of insulated con¬ ductors to an end sleeve. DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1A shows in a horizontal projection a cable clip 1 with a sleeve-shaped part 11 and a fixing element in the form of a flat part 12. The flat part 12 is provided with a hole 13 for fixing the cable clip to a bolt (not shown) . A number of only schematically shown varnish-insulated electric conductors 2a, 2b, 2c ... have been inserted, in a manner known per se, into the sleeve-shaped part of the cable clip and have been mecha- nically fixed thereto by pressing. The pressing has led to a mechanical deformation of the sleeve-shaped part of the cable clip, which is shown in the figure by a recess 14 therein. A corresponding deformation of the conductors 2a, 2b, 2c ... occurs below the recess 14, but prior to the pressing the conductors have been moved so far into the sleeve-shaped part of the cable clip that all the conductors, in the direction of insertion of the conductors into the cable clip, reach beyond the recess 14 and have not, in this region, been deformed by the pressing. Further, the cable clip exhibits a transition portion 15 between the sleeve-shaped part and the flat part, this transition portion forming a certain angle with the flat part.

Figure 2A shows a section II-II through the cable clip a:cor- ding to Figure 1A.

Based on the initial position as described with reference to Figures 1A and 2A, a section of a surface (hereinafter referred to as "cut surface") S is then produced, as illustrated in Figures IB and 2B, which cuts through all the conductors and part of the cable clip. The cut surface is produced by removing material in the transition portion 15 of the cable clip y grinding or by milling to such a depth that the cross-section ai eas 2' a, 2'b, 2'c ...of all the conductors are exposed and become accessible from the flat part of the cable clip.

Thereafter, as illustrated in Figures 1C and 2C, a solder material 3 is applied to the cut surface over the exposed cross-section areas of the conductors and over the immediately surrounding parts of the cable clip, whereafter, by heating, a mechanical and electrical connection is brought about between all the conductors and the cable clip. In this embodiment of the invention, the cut surface C substantially forms the same angle with the flat part of the cable clip as the transition portion of the cable clip formed on the non-machined cable clip.

Figure 3A shows in a horizontal projection a cable clip of the same kind as that described with reference to Figures 1A-1C and 2A- 2C, and Figure 4A shows a section IV-IV through the cable clip. In this embodiment of the invention, the cut surface S is produced by milling out material from the transition portion of the cable clip and from the conductors such that the cut surface forms a substantially right angle with the direction of insertion of the conductors in the sleeve-shaped part of the cable clip. Then, as described with reference to Figures IC and 2C and as illustrated in Figures 3B and 4B, a solder material 3 is applied to the cut surface across the exposed cross-section areas of the conductors and across the immediately surrounding parts of the cable clip, whereafter, by heating, a mechanical and electrical connection is brought about between all the conductors and with the cable clip. This embodiment entails the advantage that the soldering joint will be located in a protected manner inside the transition portion of the cable clip.

Figure 5A shows a longitudinal section through a jointing sleeve 4 of substantially circular cross section. An electric cable 5 comprises as multi-wire conductor 51 and an insulating layer 52. In a manner known per se, the insulation of the cable has been removed on part of the cable, whereupon this part has been inserted into the jointing sleeve and has been mechani¬ cally fixed thereto by pressing. The pressing has led to a mechanical deformation of the jointing sleeve, which is shown in the figure by a recess 41 in this sleeve.

A number of only schematically shown varnish-insulated conduc^¬ tors 2a, 2b, 2c ..., have then been inserted into the jointing sleeve, in a manner known per se, and have been mechanically fixed thereto by pressing. The pressing has led to a mechanical deformation of the jointing sleeve, which is shown in the figure by a recess 42 therein. A corresponding deformation of the conductors 2a, 2b, 2c ... also occurs under the recess 42, but prior to the pressing the conductors have been passed so far into the jointing sleeve that all the conductors have been brought into mechanical contact with the cross-section area S' of the multi-wire conductor 51 and, in the direction of mser- tion of the conductors in the jointing sleeve, have reached the beyond the recess 42. At the point of contact with the multi- wire conductor 51, the conductors 2a, 2b, 2c ... have thus not become deformed by the pressing.

Based on the initial position described with reference to

Figure 5A, a cut surface S is then produced, as illustrated in Figure 5B, which cuts through all the conductors 2a, 2b, 2c .. and part of the jointing sleeve. The cut surface is produced by grinding or by milling at the point of contact between the conductors 2a, 2b, 2c ... and the multi-wire conductor 51 such that a region V which is free from conductor and insulation material is formed between the cross-section area S' of this conductor and the cut surface S.

Thereafter, as illustrated in Figure 5C, a solder material 3 is applied in the region V between the cross-section area S¹ and the cut surface S, which covers the exposed cross-section areas of the conductors and the immediately surrounding parts of the jointing sleeve, whereafter, by heating, a mechanical and electrical connection is brought about between all the conduc¬ tors and with the jointing sleeve.

Figure 6A shows a longitudinal section through an end sleeve 6 of substantially circular cross section. A number of only schematically shown varnish-insulated electric conductors 2a

2b, 2c have been inserted into the end sleeve, in a manner known per se, and have been mechanically fixed thereto b^ pressing. The pressing has led to a mechanical deformation of t e end sleeve which is shown in the figure by a recess 61 therein A corresponding deformation of the conductors 2a, 2b, 2c ... also occurs under the recess 61, but prior to the pressing the conductors have been inserted so far into the end sleeve that all the conductors, in the direction of insertion of the conductors in the end sleeve, reach beyond the recess 61 and have not, in this region, been deformed by pressing.

Based on the initial position as described with reference to Figure 6A, a cut surface S is then produced, as illustrated in Figure 6B, which cuts through all the conductors 2a, 2b, 2c . . and part of the jointing sleeve. The cut surface is produced by milling or in such a way that it will comprise a shelf 62 m the end sleeve located theremside and at its far end, as viewed in the direction of insertion of the conductors.

Thereafter, as illustrated in Figure 6C, a solder material 3 is applied across the exposed cross-section area of the conductors and across the shelf 62, whereafter, by heating, a mechanical and electrical connection is brought about between all the conductors and with the jointing sleeve.

The invention is not limited to the embodiments shown but a plurality of modifications are feasible within the scope of the inventive concept Thus, in the embodiment described with reference to Figures 3A-3B and 4A-4B, it is not necessary for the cut surface to form a right angle with the direction of insertion of the conductors in the sleeve-shaped part of the cable clip. The protected position of the soldering joint desired in this embodiment may also be accomplished when the angle m question is oblique. The method illustrated m Figures 6A-6C s also advantageous in connection with so-called parallel jointing, when an electric able, for example of the kind described with reference to Figures 5A-5B, is to be joined to the conductors 2a, 2b, 2c .. The cable and the conductors 2a, 2b, 2c ...are then inserted into the end sleeve from the same direction and are both fixed mechanically thereto by pressing In this case, the cut surface S is suitably formed such that it will comprise the cross-section area S' on the conductor of the cable By the invention, a method of the kind described in the intro¬ duction is achieved, which eliminates the need of stripping of the conductors and which allows a simple, reliable and rational method for connection of insulated conductors to a connection member.

Claims

1. A method for connection of a connection member ( 1, 4, 6), exhibiting a sleeve-shaped part (11, 4, 6), to a plurality of mutually insulated electric conductors (2a, 2b, 2c ... ) , in particular varnished conductors included in a stator winding for an asynchronous machine, wherein all the conductors are inserted into the sleeve-shaped part of the connection member and are mechanically fixed thereto by pressing, characterized in that thereafter, by machining of the conductors and the sleeve-shaped part, a cut surface (S) is produced which cuts through all the conductors and part of the connection member, whereupon the cross-section areas (2'a, 2'b, 2'c ...) of the conductors, by soldering on the cut surface, are electrically connected to each other and to the connection member .

2. A method according to claim 1, characterized in that the cut surface is produced in a region (15) on the connection member located in the direction of insertion of the conductors in the connection member beyond the region (14, 42, 61) where the conductors are mechanically fixed thereto.

3. A method according to any of the preceding claims, wherein the connection member consists of a cable clip (1) comprising a sleeve-shaped part (11), a fixing element (12) and a transition portion (15) between the sleeve-shaped part and the fixing element, characterized in that the cut surface is produced in said transition portion.

4. A method according to any of claims 1-2, wherein the connec¬ tion member consists of a jointing sleeve (4) for jointing the conductors to a cable (5) , characterized in that the cut surface is produced such that a region (V) free from conductor and insulation material is formed between the cross-section area (S' ) of the conductor, belonging to the cable, and the cut surface.

5. A method according to any of claims 1-2, wherein the connection member consists of an end sleeve (5), characterized in that the cut surface through the end sleeve is produced so as to form a shelf (62) in the end sleeve located thereinside and at its far end as viewed in the direction of insertion of the conductors.

6. A method according to any of the preceding claims, characterized in that the cut surface is produced by grinding.

7. A method according to any of claims 1-5, characterized in that the cut surface is produced by milling.