Conducting wire end portion joining method, and conducting wire end portion joining structure

Abstract

A conducting wire end portion joining method is a method for conductively joining together end portions of conducting wires each covered with an insulation coating. The conducting wire end portion joining method includes: adjoining end portions of two winding wires, and bringing the end portions of the conducting wires of the two winding wires into contact with a conductive coating material stored in an insulating cap having a property of shrinking when heated; and shrinking the insulating cap by heating to fix the shrunken insulating cap around the insulation coatings of the end portions of the two winding wires, and joining together the end portions of the two winding wires by conductively connecting the conducting wires of the two winding wires via the hardened conductive coating material.

Claims

1. A conducting wire end portion joining method for conductively joining together end portions of conducting wires each covered with an insulation coating, the conducting wire end portion joining method comprising: aligning end portions of conducting wires with end portions of insulation coatings of the conducting wires while adjoining the insulation coatings of side surfaces of the end portions of two winding wires, and bringing end surfaces of the end portions of the conducting wires of the two winding wires into contact with a conductive coating material stored in an insulating cap having a property of shrinking when heated; and shrinking the insulating cap by heating to fix the shrunken insulating cap around the insulation coatings of the end portions of the two winding wires, and joining together the end portions of the two winding wires by conductively connecting the conducting wires of the two winding wires via the hardened conductive coating material.

2. The conducting wire end portion joining method according to claim 1, wherein the conductive coating material contains a thermosetting resin.

3. The conducting wire end portion joining method according to claim 1, wherein: the conducting wires are made of copper; and the conductive coating material is a material in which copper or silver is dispersed in a thermosetting resin.

4. The conducting wire end portion joining method according to claim 1, wherein the insulating cap is made of fluorinated ethylene propylene that is a copolymer of tetrafluoroethylene and hexafluoropropylene.

5. The conducting wire end portion joining method according to claim 1, wherein the insulating cap is made of polytetrafluoroethylene.

6. The conducting wire end portion joining method according to claim 1, wherein each of the conducting wires is a flat conducting body, and the end portions of the conducting wires are end portions of the flat conducting bodies of coil ends of a motor.

7. The conducting wire end portion joining method according to claim 1, wherein the side surfaces are directly adjacent to the end surfaces of the end portions.

8. The conducting wire end portion joining method according to claim 1, wherein the insulation coatings are formed around the conducting wires in the end surfaces of the end portions of the conducting wires of the two winding wires.

9. A conducting wire end portion joining structure comprising: two winding wires; and an insulating cap, wherein end portions of conducting wires of the two winding wires are conductively joined together, each of the conducting wires being covered with an insulation coating, insulation coatings of side surfaces of end portions of two winding wires are adjoined while the end portions of the conducting wires are aligned with end portions of the insulation coatings, end surfaces of the end portions of the conducting wires of the two winding wires are in contact with a conductive coating material in the insulating cap, and the conducting wires of the two winding wires are conductively connected together via the conductive coating material, and the insulating cap is fixed around the insulation coatings of the end portions of the two winding wires.

10. The conducting wire end portion joining structure according to claim 9, wherein the conductive coating material contains a thermosetting resin.

11. The conducting wire end portion joining structure according to claim 9, wherein: the conducting wires are made of copper; and the conductive coating material is a material in which copper or silver is dispersed in a thermosetting resin.

12. The conducting wire end portion joining structure according to claim 9, wherein the insulating cap is made of fluorinated ethylene propylene that is a copolymer of tetrafluoroethylene and hexafluoropropylene.

13. The conducting wire end portion joining structure according to claim 9, wherein the insulating cap is made of polytetrafluoroethylene.

14. The conducting wire end portion joining structure according to claim 9, wherein each of the conducting wires is a flat conducting body, and the end portions of the conducting wires are end portions of the flat conducting bodies of coil ends of a motor.

15. The conducting wire end portion joining structure according to claim 9, wherein the side surfaces are directly adjacent to the end surfaces of the end portions.

16. The conducting wire end portion joining structure according to claim 9, wherein the insulation coatings are formed around the conducting wires in the end surfaces of the end portions of the conducting wires of the two winding wires.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

(2) FIG. 1A is a front view illustrating a first step in a conducting wire end portion joining method of the invention;

(3) FIG. 1B is an arrow view taken in the direction of an arrow b in FIG. 1A, FIG. 1B illustrating the first step in the conducting wire end portion joining method of the invention;

(4) FIG. 2 is a view illustrating the first step continuing on from FIGS. 1A and 1B; FIG. 3 is a view illustrating a second step in the conducting wire end portion joining method, FIG. 3 illustrating a conducting wire end portion joining structure of the invention;

(5) FIG. 4A is a view illustrating a conducting wire end portion joining method according to related art;

(6) FIG. 4B is an arrow view taken in the direction of an arrow b in FIG. 4A;

(7) FIG. 4C is a view illustrating the conducting wire end portion joining method according to the related art, FIG. 4C illustrating a process subsequent to that in FIG. 4A;

(8) FIG. 4D is a view illustrating the conducting wire end portion joining method according to the related art, FIG. 4D illustrating a process subsequent to that in FIG. 4C; and

(9) FIG. 4E is a view illustrating the conducting wire end portion joining method according to the related art, FIG. 4E illustrating a process subsequent to that in FIG. 4D.

DETAILED DESCRIPTION OF EMBODIMENTS

(10) Hereinafter, a conducting wire end portion joining method and a conducting wire end portion joining structure according to example embodiments of the invention will be described with reference to the accompanying drawings. The winding wire in the drawings is a flat wire, but the winding wire used in the conducting wire end portion joining method according to the invention may of course be a round wire having a circular cross-section.

(11) Conducting Wire End Portion Joining Method and Conducting Wire End Portion Joining Structure According to Example Embodiments

(12) FIG. 1A is a front view illustrating a first step in the conducting wire end portion joining method of the invention. FIG. 1B is an arrow view taken in the direction of an arrow b in FIG. 1A, and FIG. 1B illustrates the first step in the conducting wire end portion joining method of the invention. FIG. 2 is a view illustrating the first step continuing on from FIGS. 1A and 1B. FIG. 3 is a view illustrating a second step in the conducting wire end portion joining method of the invention, and FIG. 3 illustrates a conducting wire end portion joining structure of the invention.

(13) First, end portions 3a of two winding wires 3 are adjoined to each other at coil ends, as shown in FIG. 1.

(14) Each of the winding wires 3 includes a conducting wire 1 (a flat conducting body) having a rectangular cross-section, and an insulation coating 2 formed around the conducting wire 1.

(15) The conducting wire 1 is made of oxygen-free copper or tough-pitch copper.

(16) The insulation coating 2 is made of a highly heat resistant thermosetting resin, such as polyimide (PI) or polyamide-imide (PAI), or is made of a thermoplastic resin, such as polyether ether ketone (PEEK), polyphenylene sulfide (PPS), or a fluororesin.

(17) Next, as shown in FIG. 2, the end portions 3a of the two adjoined conducting wires 1 are dipped (in a direction X1) in a conductive coating material 5 stored in an insulating cap 4 such that the end portions 3a are brought into contact with the conductive coating material 5 (the first step has been described so far).

(18) The insulating cap 4 is made of fluorinated ethylene propylene (FEP) that is a copolymer of tetrafluoroethylene and hexafluoropropylene, or made of polytetrafluoroethylene (PTFE). FEP and PTFE are highly heat resistant and shrink when heated.

(19) The conductive coating material 5 is a copper paste (in which copper is dispersed in a thermosetting resin) or a silver paste (in which silver is dispersed in a thermosetting resin). Each of the copper paste and the silver paste has an electrical resistance close to that of copper.

(20) The end portions of the two winding wires 3 (the conducting wires 1) are adjoined to each other, and then brought into contact with the conductive coating material 5 stored in the insulating cap 4. Subsequently, the insulating cap 4 is shrunk by being heated with, for example, a heater (not shown), so that the shrunken insulating cap 4 is fixed around the insulation coatings 2 of the end portions 3a of the two winding wires 3, as shown in FIG. 3.

(21) The conducting wires 1 of the two winding wires 3 are conductively connected together via the hardened conductive coating material 5, so that the end portions 3a of the conducting wires 1 are joined together to form a conducting wire end portion joining structure 10 (the second step).

(22) The conducting wire end portion joining method according to the related art requires three different processes, that is, a process of stripping off coatings of end portions of winding wires, a welding process, and a process of forming an insulation coating. In contrast to this, according to the illustrated conducting wire end portion joining method in the present embodiment, the end portions 3a of the two winding wires 3 are joined together through a single continuous process in which the end portions 3a of the two winding wires 3 are brought into contact with the conductive coating material 5 and heating is performed. Thus, the number of processes is significantly reduced as compared with the conducting wire end portion joining method according to the related art. As a result of the reduction in the number of processes, equipment costs are also significantly reduced.

(23) The conducting wire end portion joining structure 10 is formed by bringing the end portions 3a of the two conducting wires 1 into contact with the conductive coating material 5 and then hardening the conductive coating material 5. Thus, the height (height t2 in FIG. 3) of the conducting wire end portion joining structure 10 is significantly lower than that of the conducting wire end portion joining structure according to the related art. Because the height of a joint portion at the coil ends is lower, the physical size of the coils is smaller than that of the conducting wire end portion joining structure according to the related art.

(24) A specific embodiment will be described below. In this specific embodiment, flat wires (with sectional dimensions of 1.7 mm3.0 mm) each including a conducting wire made of oxygen-free copper and an insulation coating made of polyamide-imide are used. In this specific embodiment, a conductive coating material made of a silver paste is stored in a shrinkable tube made of FEP. Then, end portions of the two flat wires are dipped into the conductive coating material, and the tube is shrunk by being heated at a temperature of 210 C., so that the tube is fixed around the end portions. In this way, the end portions of the winding wires are joined together.

(25) Heretofore, one example embodiment of the invention has been described in detail with reference to the drawings, but the specific structure is not limited to that in this example embodiment. The invention also includes design modifications and the like within the scope of the invention.