Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2003-06-24
2004-12-21
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S198000, C310S201000, C310S208000
Reexamination Certificate
active
06833648
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates generally to a sequentially joined-segment coil of a rotary electric machine and a production method thereof which ensures a high degree of electrical insulation and allows decreases in size and weight thereof.
2. Background Art
Sequentially joined-segment stator coils have been proposed which are made by conductor segments inserted in slots in a stator core whose ends are joined in sequence. For instance, Japanese Patent No. 3118837 (U.S. Pat. No. 6,249,956), assigned to the same assignee as that of this application, discloses a production method of joining U-shaped conductor segments in sequence to make a stator coil.
The sequentially joined segment stator coil, as taught in the above patents, is made by inserting a pair of legs of each conductor segment into two of slots of a core located at an interval away from each other which is substantially equivalent to a magnetic pole pitch of a rotor, bending end portions of the legs projecting from the slots in a circumferential direction of the core, and joining the end portions of the conductor segments in series.
The conductor segments each consist of a U or V-shaped head (also called a turn), a pair of side conductor portions extending from the head to be inserted into two of the slots of the core from an axial direction of the core, and end portions which project from the side conductor portions toward the other side of the slots and extend in the circumferential direction of the core. The projecting end portions are joined in pair. In the following discussion, the side conductor portion and the projecting end portion will also be referred to as a leg as a whole, the heads of the conductor segments will also be referred to as a segment head-side coil end of the stator coil, and the projecting end portions will also be referred to as a segment end-side coil end of the stator coil.
Japanese Patent Publication No. 3118837 (U.S. Pat. No. 6,249,956) also discloses a method of forming slant portions of a head of each of a small-sized conductor segment and a large-sized segment. The formation of the slant portions is achieved by fitting a total of four legs of a set of the small-sized conductor segment and the large-sized segment extending over the small-sized segment within two rings arrayed coaxially with each other and rotating the rings in opposite directions to spread the legs in circumferential directions of the rings.
Japanese Patent First Publication No. 2000-139049 (U.S. Pat. No. 6,177,747) discloses a method of forming the slant portions of the head of each conductor segment which is achieved by fitting a total of four legs of a set of the small-sized conductor segment and the large-sized segment extending over the small-sized segment within four rings arrayed coaxially with each other and rotating the rings in opposite directions to spread the legs of each conductor segment in circumferential directions of the rings.
Japanese Patent No. 3104700 (U.S. Pat. No. 6,403,921) discloses welding two of tips of end portion of conductor segments arrayed adjacent to each other in the radius direction of a stator core and teaches use of a restraint member which is disposed between the adjacent two of the tips to secure a desired orientation of the welded tips.
Japanese Patent No. 3118837 (U.S. Pat. No. 6,249,956) discloses bending a conductor bar through 180° to produce a U-shaped segment. Japanese Patent First Publication No. 2001-245446 teaches bending wire 180° many times to make the same coil as the above described sequentially joined-segment stator coil. This type of stator coil eliminates the need for a welding process, but requires use of a stator coil with open slots indispensably.
Japanese Patent Fist Publication No. 2000-92766 (U.S. Pat. No. 6,201,332) discloses a sequentially joined-segment stator coil in which six legs of conductor segments are aligned within each slot of a stator core in a radius direction of the stator core.
An example of the production methods of the sequentially joined-segment stator coil as taught in the above publications will be discussed below in detail.
First, a required number of pine needle-like conductor segments are prepared. Each of the conductor segments is formed into a U-shape one with side conductor portions extending at substantially a magnetic pole pitch interval away from each other. The side conductor portions of each conductor segment are placed spatially in alignment with two of the slots formed in the core, respectively, (i.e., in a circumferential direction of the core) for simultaneous insertion of the side conductor portions into the slots. These steps may be achieved with a pair of coaxially arrayed rings with slots, as illustrated in FIG. 3 of Japanese Patent No. 3118837. Specifically, legs of each conductor segment are fitted in two of the slots aligned in a radius direction of the rings. Next, the rings are turned relative to each other through a given angle equivalent to a magnetic pole pitch to spread the legs, thereby forming the U-shaped conductor segment.
Subsequently, the head of each of the U-shaped conductor segments is held. The legs are drawn from the slots and then inserted into the slots of the core.
Next, end portions of the legs projecting from the slots are bent in the circumferential direction of the core through half a magnetic pole pitch. Such bending may be achieved with a plurality of coaxially arrayed rings with slots, as illustrated in FIGS. 4 and 5 of Japanese Patent No. 03196738. Specifically, tips of the projecting end portions of the legs are inserted into the slots of the rings. The rings are rotated in the circumferential direction by half a magnetic pole pitch (i.e., an electrical angle of &pgr;/2) to bent the projecting end portions in the circumferential direction through half the magnetic pole pitch. It is advisable that the rotation of the rings be performed while urging the rings toward the projecting end portions (i.e., the axial direction of the core) for increasing the radius of curvature of the turn of each conductor segment. Next, the projecting end portions are welded in a given sequence, thereby forming an endless phase coil. Any one of the heads of the U-shaped conductor segments is cut to define coil terminals. If the coil terminals are made longer and bent in the circumferential direction, they may be employed as a neutral point connecting line. The reason that the coil terminals are provided in the segment head-side coil end is because if the coil terminals are provided in the segment end-side coil end, they will interface with welding of the end portions of the conductor segments.
The above sequentially joined-segment stator coil is usually employed as a stator coil of automotive ac generators and has suffered from the following drawback.
Each of the pine needle-like conductor segments for use in making the U-shaped conductor segment has the 180° bent head which is greater in width than a total width of legs of each of the conductor segments because the head is bent with a certain curvature. This increases the damage to insulating coatings on the heads of the conductor segment. The problems is also encountered by the multi-bend coils as taught in Japanese Patent First Publication No. 2001-245446.
Typically, the legs of each of the conductor segments are placed within one of slots of the stator core at different locations aligned in the radius direction of the stator core. Alternatively, the set of the large-sized and small-sized conductor segments has a total of four legs disposed within one of the slots at four adjacent locations.
Usually, electric motors used to drive automotive vehicles is supplied with power from a high-voltage battery. It is, thus, very difficult to decrease the curvature of the heads of the conductor segments as compared with typical automotive ac generators, which results in a great increase in diameter of the segment head-side coil end of the stator coil made up of the heads of the conductor segments.
The segme
Gorohata Tetsuya
Hirano Hitoshi
Kamakura Youichi
Kouda Shinji
Seguchi Masahiro
Denso Corporation
Nguyen Tran
LandOfFree
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