Alternator with identical conductor segments

In an automotive alternator according to the present invention, conductor segments of an inner winding portion and conductor segments of an outer winding portion have substantially the same shape.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an automotive alternator mounted to an automotive vehicle such as a passenger car or a truck, for example, and particularly to a stator winding of a stator therefor.

2. Description of the Related Art

Conventionally, automotive alternators are known that include a rotor in which north-seeking (N) and south-seeking (S) poles are formed alternately in a direction of rotation; and a stator having a stator core surrounding the rotor, and a stator winding mounted in a plurality of slots formed so as to extend in an axial direction of the stator core at a distance from each other in a circumferential direction, wherein the stator winding is constructed such that a plurality of conductor segments are connected to each other, the conductor segments being formed into a general U shape composed of a pair of straight portions housed inside the slots, a linking portion linking these straight portions to each other, and joining portions disposed on tip portions of the straight portions and projecting outward from a first end surface of the stator core; and in the linking portions, which constitute a coil end of the stator winding, linking portions of first conductor segments cover linking portions of second conductor segments. (See Patent Literature 1, for example.)

Patent Literature 1

In such cases, because linking portions of first conductor segments cover linking portions of second conductor segments, one problem is that we must prepare at least two kinds of conductor segments, which means that manufacturing costs increase.

SUMMARY OF THE INVENTION

The present invention aims to solve the above problem and an object of the present invention is to provide an alternator which reduces manufacturing costs.

In order to achieve the above object, according to one aspect of the present invention, conductor segments of an inner winding portion and conductor segments of an outer winding portion are constituted by parts with a substantially identical shape.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1is a cross section showing an automotive alternator according to Embodiment 1 of the present invention,FIG. 2is a partial perspective view of a stator7inFIG. 1andFIG. 3is a diagram of a stator7fromFIG. 1when viewed in a direction of arrow A.

This automotive alternator includes: a case3constituted by a front bracket1and a rear bracket2made of aluminum; a shaft5disposed inside the case3, a pulley4being secured to a first end portion of the shaft5; a Lundell-type rotor6secured to the shaft5; a stator7secured to an inner wall surface of the case3; slip rings8secured to a second end portion of the shaft5for supplying an electric current to the rotor6; a pair of brushes9sliding in contact with the slip rings8; a brush holder10housing the brushes9; a rectifier11electrically connected to the stator7for converting an alternating current generated in the stator7into a direct current; and a regulator13fixed by adhesive to a heat sink12secured to the brush holder10, the regulator13adjusting a magnitude of a voltage.

The rotor6is constituted by: a rotor coil14for generating a magnetic flux on passage of an electric current; and a pair of pole cores15and16disposed so as to cover the rotor coil14, magnetic poles being formed in the pair of pole cores15and16by the magnetic flux generated by the rotor coil14. The first and second pole cores15and16are made of iron, each having a plurality of first and second claw-shaped magnetic poles17and18, respectively, disposed on an outer circumferential edge at a uniform angular pitch in a circumferential direction so as to project axially, and the first and second pole cores15and16are fixed to the shaft5facing each other such that the first and second claw-shaped magnetic poles17and18intermesh. In addition, centrifugal fans19are fixed to first and second axial end surfaces of the rotor6.

The stator7is constituted by: an annular stator core21having a total of ninety-six (96) slots20formed so as to extend in an axial direction at a uniform pitch in a circumferential direction; and a stator winding22in which conducting wires are wound into this stator core21and an alternating current is generated by changes in the magnetic flux from the rotor6accompanying rotation of the rotor6.

This stator winding22is constituted by a-phase stator winding portions, b-phase stator winding portions, and c-phase stator winding portions, disposed so as to be shifted in a circumferential direction by one slot from each other and star-connected to each other to form two three-phase stator windings.

FIG. 4is a winding diagram for one of the a-phase stator winding portions23; winding diagrams for the other a-phase stator winding portion, the b-phase stator winding portions, and the c-phase stator winding portions are not shown. Moreover, in this diagram, the solid lines in the figure represent the conducting wires at a rear bracket2end (linking portions of the conductor segments described below), and the broken lines represent the conducting wires at a front bracket1end (the joining portions of the conductor segments described below). The numerals written on an inner circumferential side of the stator core21inFIG. 4represent slot numbers of the slots20of the stator core21.

The a-phase stator winding portion23is constituted by an inner winding portion24and an outer winding portion25.

InFIG. 4, the conducting wire of the inner winding portion24in a first position from an inner circumferential side of the slots20at slot number31, for example, (hereinafter, the first position from the inner circumferential side is called Address1, the second position Address2, the third position Address3, and the fourth position Address4) extends in a clockwise direction from the rear bracket2end and enters a slot20at Address2of slot number37, passes through the slot20, and exits at the front bracket1end. Next, the conducting wire extends in a clockwise direction from the front bracket1end and enters a slot20at Address1of slot number43, passes through the slot20, and exits at the rear bracket2end. Finally, the conducting wire extends in a clockwise direction from the rear bracket2end and enters a slot20at Address2of slot number49.

The conducting wire of the inner winding portion24in Address1of the slots20at slot number25, for example, extends in a clockwise direction from the rear bracket2end and enters a slot20at Address2of slot number31, passes through the slot20, and exits at the front bracket1end. Next, the conducting wire extends in a clockwise direction from the front bracket1end and enters a slot20at Address1of slot number37, passes through the slot20, and exits at the rear bracket2end. Finally, the conducting wire extends in a clockwise direction from the rear bracket2end and enters a slot20at Address2of slot number43.

Thus, in the inner winding portion24, the conducting wires are wound around inside the slots20while being disposed repeatedly in an Address1layer and an Address2layer inside every sixth slot20skipping five slots in a circumferential direction from the Address1layer.

InFIG. 4, the conducting wire of an outer winding portion25in a Address3of the slots20at slot number31, for example, extends in a clockwise direction from the rear bracket2end and enters a slot20at Address4of slot number37, passes through the slot20, and exits at the front bracket1end. Next, the conducting wire extends in a clockwise direction from the front bracket1end and enters a slot20at Address3of slot number43, passes through the slot20, and exits at the rear bracket2end. Finally, the conducting wire extends in a clockwise direction from the rear bracket2end and enters a slot20at Address4of slot number49.

InFIG. 4, the conducting wire of the outer winding portion25in Address3of the slots20at slot number25, for example, extends in a clockwise direction from the rear bracket2end and enters a slot20at Address4of slot number31, passes through the slot20, and exits at the front bracket1end. Next, the conducting wire extends in a clockwise direction from the front bracket1end and enters a slot20at Address3of slot number37, passes through the slot20, and exits at the rear bracket2end. Further, the conducting wire extends in a clockwise direction from the rear bracket2end and enters a slot20at Address4of slot number43.

Thus, in the outer winding portion25, the conducting wires are wound around inside the slots20while being disposed repeatedly in an Address3layer and an Address4layer inside every sixth slot20skipping five slots in a circumferential direction from the Address3layer.

Moreover, the other a-phase stator winding portion, the b-phase stator winding portions, and the c-phase stator winding portions are similar to the a-phase stator winding portion23, and explanation thereof will be omitted.

The outer winding portion25is constructed by connecting conductor segments26A, as shown inFIG. 5. The inner winding portion24is constructed by connecting conductor segments26B, as shown inFIG. 6. An overall conductor segment length of the conductor segments26A when straight is equal to an overall conductor segment length of the conductor segments26B when straight.

The conductor segments26A and26B, which constitute structural elements of the conducting wires, are made of a copper wire material having a round cross-sectional shape coated with an electrical insulator shaped into a general U shape, and are each constituted by: a pair of straight portions27housed inside the slots20; a linking portion28linking the straight portions27to each other; and joining portions29disposed on tip portions of the straight portions27and spread outward to join adjacent conductor segments26A and26B to each other.

Next, a procedure for forming an a-phase stator winding portion23using the conductor segments26A and26B will be explained.

First, first straight portions27of the conductor segments26A and26B and second straight portions27six slots away are inserted from the rear bracket2end into predetermined slot numbers and addresses, four straight portions27of the conductor segments26A and26B being arranged so as to line up radially in a single column in each of the slots20.

In this case, because the conductor segments26B of the inner winding portion24are disposed radially inward compared to the conductor segments26A of the outer winding portion25, making the distance between the slots20in a circumferential direction proportionately shorter, they are inserted inside the slots20while deforming, as indicated by the arrows B inFIG. 6.

Thereafter, the joining portions29projecting outward from the straight portions27at the front bracket1end and the joining portions29projecting outward from straight portions27six slots away are joined together at the front bracket1end, as indicated by the broken lines in the winding diagram inFIG. 4, forming a four-turn a-phase stator winding portion23. Moreover, as can be seen from the broken lines inFIG. 4, in the inner winding portion24, each of the joining portions29of the conductor segments26projecting outward at the front bracket1end from Address1inside the slots20are joined together at the front bracket1end with the respective joining portions29of the conductor segments26projecting outward at the front bracket1end from Address2inside slots20six slots away in a counterclockwise direction. Each of the joining portions29of the conductor segments26projecting outward at the front bracket1end from Address2inside the slots20are joined together at the front bracket1end with the respective joining portions29of the conductor segments26projecting outward at the front bracket1end from Address1inside slots20six slots away in a clockwise direction.

As can be seen from the broken lines inFIG. 4, in the outer winding portion25, each of the joining portions29of the conductor segments26projecting outward at the front bracket1end from Address3inside the slots20are joined together at the front bracket1end with the respective joining portions29of the conductor segments26projecting outward at the front bracket1end from Address4inside slots20six slots away in a counterclockwise direction. Each of the joining portions29of the conductor segments26projecting outward at the front bracket1end from Address4inside the slots20are joined together at the front bracket1end with the respective joining portions29of the conductor segments26projecting outward at the front bracket1end from Address3inside slots20six slots away in a clockwise direction.

Tip portions of the joining portions29of the conductor segments26A and26B are superposed radially at a position generally midway between the pairs of slots20in which the conductor segments26are inserted to facilitate a bending process, a clamp is wound on, then the tip portions are welded to each other with solder.

In this manner, in the inner winding portion24, a joining portion coil end40is formed in which a plurality of connection portions in which tip portions of the joining portions29are connected to each other are each arranged in a row in a circumferential direction.

In the outer winding portion25, a joining portion coil end41is formed in which a plurality of connection portions in which tip portions of the joining portions29are connected to each other are each arranged in a row in a circumferential direction.

In the inner winding portion24, a linking portion coil end42is formed in which a plurality of linking portions28are each arranged in a row in a circumferential direction.

In the outer winding portion25, a linking portion coil end43is formed in which a plurality of linking portions28are each arranged in a row in a circumferential direction.

In this embodiment, the conductor segments26B of the inner winding portion24and the conductor segments26A of the outer winding portion25are constituted by parts with a substantially identical shape, therefore a height F1of the joining portion coil ends40of the inner winding portion24is higher than a height F2of the joining portion coil ends41of the outer winding portion25. Also, a height R1of the linking portion coil ends42of the inner winding portion24is higher than a height R2of the linking portion coil ends43of the outer winding portion25.

Another a-phase stator winding portion; b-phase stator winding portions, and c-phase stator winding portions each having four turns are formed in a similar manner, and then these phase stator winding portions are star-connected to form three-phase stator windings.

In an automotive alternator constructed in this manner, an electric current is supplied to the rotor coil14from a battery (not shown) by means of the brushes9and the slip rings10, generating a magnetic flux. The claw-shaped magnetic poles17in the first pole core15are magnetized into north-seeking (N) poles by this magnetic flux, and the claw-shaped magnetic poles18in the second pole core16are magnetized into south-seeking (S) poles. At the same time, rotational torque from an engine is transmitted to the shaft5by means of a belt (not shown) and the pulley4, rotating the rotor6. Thus, a rotating magnetic field is imparted to the stator winding22, generating an electromotive force in the stator winding22. This alternating-current electromotive force passes through the rectifier11and is converted into a direct current, the magnitude thereof is adjusted by the regulator13, and the battery is charged.

Due to rotation of the centrifugal fans19secured to the first and second axial end surfaces of the rotor6, at the rear bracket2end, external air is drawn in through the rear-end air intake apertures31, cooling the rectifiers11and the regulator13, is then deflected centrifugally by the centrifugal fans19, cooling the linking portion coil ends42and43of the stator winding22, and is discharged externally through the rear-end air discharge apertures32, as indicated by arrows C inFIG. 1. At the front bracket1end, external air is drawn in through the front-end air intake apertures31, is then deflected centrifugally by the centrifugal fans19, cooling the joining portion coil ends40and41of the stator winding22, and is discharged externally through front-end air discharge apertures32, as indicated by arrows D inFIG. 1.

In an automotive according to this embodiment, the conductor segments26B of the inner winding portion24and the conductor segments26A of the outer winding portion25are constituted by parts with a substantially identical shape, enabling a single specification for the conductor segments in both the conductor segments26A and the conductor segments26B before reshaping, thereby reducing manufacturing costs.

More, as the conductor segments26B constituting the inner winding portion24is identical to the conductor segments26A constituting the outer winding portion25, the conductor segments26B of the inner winding portion25may be inserted into the slots20while deforming externally, as indicated by the arrows C inFIG. 7, the conductor segments26B of the inner winding portion24may be inserted into the slots20as it is.

Further, a three-phase stator winding22in which the conductors make four turns is explained, but if high output is further required at low speed, the number of turns of the conducting wires may also be six turns or eight turns.

The present invention is not limited to automotive alternators, and can also be applied to alternators for outboard motors, for example.