STATOR FOR ROTARY ELECTRIC MACHINE AND MANUFACTURING APPARATUS THEREOF

A stator for a rotary electric machine includes a stator coil configured such that a tip end of a conductor segment bent in a stator circumferential direction is joined to a tip end of another conductor segment in the same phase. A conductive material is exposed from the tip ends of the conductor segments, and a distance between the tip ends in different phases and adjacent to each other in the stator circumferential direction is larger than a distance between the tip ends in the same phase and adjacent to each other in the stator circumferential direction.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2017-046464 filed on Mar. 10, 2017 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a stator for a rotary electric machine and a manufacturing apparatus thereof, and particularly to a stator for a rotary electric machine including a stator coil configured such that a tip end of a conductor segment projecting from a slot of a stator core is joined to a tip end of another conductor segment in the same phase.

2. Description of Related Art

There is a segment coil as a stator coil wound around a stator core of a rotary electric machine. The segment coil is configured such that a conductor segment made of a flat lead wire bent in a U-shape is inserted into a slot of a stator core, and a part projecting from the slot is bent in a stator circumferential direction, so as to be joined by welding to a tip end of another conductor segment, for example.

Surfaces of the conductor segments are covered with insulating coatings, and at the time of welding, the insulating coatings of the tip ends of the conductor segments to be joined are removed. The tip ends (conductor exposed parts) where the insulating coatings are removed are joined to each other by welding by TIG arc welding (Tungsten Inert Gas welding) or laser irradiation (e.g., see Japanese Patent Application Publication No. 2014-007795 (JP 2014-007795 A)).

SUMMARY

In recent years, a rotary electric machine has been downsized, and a diameter of a stator core including segment coils tends to be reduced. When the diameter of the stator core is reduced, a joining part (a tip end) of a conductor segment forming a segment coil and a joining part of its adjacent conductor segment in a different phase is shortened, which makes it difficult to secure an insulating property between the joining parts.

Particularly, like a stator described in JP 2014-007795 A, in a case of a segment coil having a structure in which linear parts of conductor segments are eliminated and intersecting parts of the conductor segments are joined to each other by laser irradiation, a creepage distance between joining parts of the conductor segments are short, which makes it difficult to secure the insulating property.

Further, it is also conceivable that the joining parts of the conductor segments are coated with insulation resin. However, a step of insulating the joining parts after welding is required and an insulation resin material to coat the joining parts is also required, which increases costs.

In view of this, the present disclosure improves an insulating property of joining parts of conductor segments in a stator including a segment coil.

A first aspect of the present disclosure relates to a stator for a rotary electric machine. The stator includes: a stator core including slots provided at a plurality of positions in a circumferential direction; and a stator coil configured such that a tip end of a conductor segment projecting from a stator-core axial end of each of the slots and bent in the circumferential direction of the stator core is joined to a tip end of another conductor segment in the same phase. A conductive material is exposed from the tip ends of the conductor segments, and a distance between the tip ends in different phases and adjacent to each other in the circumferential direction of the stator core is larger than a distance between the tip ends in the same phase and adjacent to each other in the circumferential direction of the stator core.

With the above configuration, in the stator including a segment coil, it is possible to improve an insulating property between joining ends of the conductor segments.

In the stator for the rotary electric machine, a distance between the conductor segments in different phases and adjacent to each other in the circumferential direction of the stator core may be larger than a distance between the conductor segments in the same phase and adjacent to each other in the circumferential direction of the stator core.

A second aspect of the present disclosure relates to a manufacturing apparatus for a stator for a rotary electric machine. The manufacturing apparatus includes a jig configured to bend, in a stator-core circumferential direction, conductor segments projecting from stator-core axial end surfaces of slots provided in a stator core. The jig includes a first jig configured to bend one conductor segment out of the conductor segments in the same phase and adjacent to each other in the stator-core circumferential direction, and a second jig configured to bend the other conductor segment. The second jig is configured to bend the other conductor segment such that a tip end of the other conductor segment approaches a tip end of the one conductor segment at a time when the first jig bends the one conductor segment.

In the manufacturing apparatus for the stator for the rotary electric machine, the first jig may include a protrusion configured to bend the one conductor segment. The protrusion may include a tilting surface configured to abut with the tip end of the one conductor segment and to tilt and bend the one conductor segment in the circumferential direction, and a position defining surface configured to define a position of the tip end of the one conductor segment after the one conductor segment is bent.

DETAILED DESCRIPTION OF EMBODIMENTS

A configuration of a stator20for a rotary electric machine is described with reference to the drawings. Note that, in the following description, an “axial direction,” a “circumferential direction,” and a “radial direction” indicate an axial direction, a circumferential direction, and a radial direction of the stator20for the rotary electric machine.

As illustrated inFIG. 1, the stator20for the rotary electric machine includes a stator core22and a stator coil24. The stator core22is configured such that a plurality of electromagnetic steel sheets is laminated in an axial direction. The stator core22includes a generally cylindrical yoke26, and a plurality of teeth28projecting radially inward from an inner peripheral edge of the yoke26. The plurality of teeth28is disposed at regular intervals in the circumferential direction, and a slot30, which is a space where the stator coil24is placed, is formed between two adjacent teeth28.

The stator coil24includes a U-phase coil, a V-phase coil, and a W-phase coil. The stator coil24is configured as a segment coil, and the segment coil is configured such that a plurality of conductor segments32is joined to each other.

FIG. 2illustrates one conductor segment32before assembling to the stator core22. As illustrated inFIG. 2, the conductor segment32is formed such that a flat conductive material having a generally rectangular section and coated with insulation resin is bent generally in a U-shape. At a stage before the assembling to the stator core22, the conductor segment32includes a pair of linear parts50, and a connecting part34that connects the pair of linear parts50to each other.

At the time when the conductor segment32is assembled to the stator core22, the pair of linear parts50are inserted into respective slots30. Hereby, the connecting part34extends in the circumferential direction so as to cross a plurality of teeth28on a second axial end side of the stator core22. Further, tip ends40of the linear parts50are inserted into the slots30and then bent in the circumferential direction in a middle thereof as indicated by an alternate long and two short dashes line inFIG. 2. Hereby, the linear parts50become leg parts36extending in the axial direction inside the slots30, and bridge parts38extending in the circumferential direction on a first axial end side of the stator core22.

The conductor segment32is coated with the insulation resin as described above, but the insulation resin is removed only from the tip ends40of the linear parts50. This is to secure electrical connection with other conductor segments32. The tip ends40are joined to each other by welding or the like. This joining will be described later.

Next will be described an arrangement of the conductor segments32and the tip ends40with reference toFIGS. 3 and 4.FIG. 3schematically illustrates an arrangement relationship of the tip ends40of the conductor segments32in a coil end, andFIG. 4is an enlarged view of a part A inFIG. 3. The enlarged view of the part A illustrates tip ends40of a U1-phase, a U2-phase, a V1-phase, and a V2-phase. Note that, inFIGS. 3 and 4, a reference sign of a corresponding phase is assigned to each conductor segment32and each tip end40.

As illustrated inFIG. 3, the conductor segments32are placed repeatedly in an order of the U1-phase, the U2-phase, the V1-phase, the V2-phase, a W1-phase, and a W2-phase in the circumferential direction. As illustrated inFIG. 4, a tip-end distance G1abetween tip ends40U2,40V1in different phases (e.g., the U2-phase and the V1-phase) and adjacent to each other in the circumferential direction is larger than a tip-end distance G2abetween tip ends40U1,40U2in the same phase (the U1-phase and the U2-phase) and adjacent to each other in the circumferential direction. That is, a relationship of the tip-end distance G1ain different phases >the tip-end distance G2ain the same phase is established.

Further, a conductor-segment distance G1bin the axial direction between conductor segments32U2,32V1in different phases (e.g., the U2-phase and the V1-phase) and adjacent to each other in the circumferential direction is larger than a conductor-segment distance G2bin the axial direction between conductor segments32U1,32U2in the same phase (e.g., the U1-phase and the U2-phase) and adjacent to each other in the circumferential direction. That is, a relationship of the conductor-segment distance G1bin different phases >the conductor-segment distance G2bin the same phase is satisfied. Further, a conductor-segment distance G1cin different phases in an orthogonal direction to surfaces of the conductor segments32is larger than a conductor-segment distance G2cin the same phase.

Referring back toFIG. 3, as a method for defining sizes of the tip-end distances G1a, G2aand the conductor-segment distances G1b, G1c, G2b, G2c, at the time of bending the conductor segment32U2, a position of the tip end40U2of the conductor segment32U2is adjusted so that the tip end40U2of the conductor segment32U2approaches the tip end40U1of the conductor segment32U1.

That is, tip ends of conductor segments in the related art are placed at regular intervals (at a distance P1), but in the present embodiment, the conductor segment32U2is bent so that the tip end40U2approaches the tip end40U1, that is, a distance between the tip end40U2and the tip end40U1in the same phase is a distance P2(P2<P1), which is smaller than the distance P1. On this account, a distance between the tip end40U2and the tip end40V1in different phases is a distance P3(P3>P1), which is larger than the distance P1. Further, a distance by which the tip end40U2approaches the tip end40U1is a distance L1(=P1−P2). The distance L1is set based on a specification of the conductor segment32U2or the tip end40U2appropriately. As a result, the distance P3>the distance P2is established, so that the relationship of the tip-end distance G1a>the tip-end distance G2ais established.

Further, similarly, in terms of tip ends40V2,40W2of conductor segments32V2,32W2, positions of the tip ends40V2,40W2are adjusted at the time of bending the conductor segments32V2,32W2. Note that a specific position adjustment of the tip ends40U2,40V2,40W2will be described later.

Next will be described the bending of the conductor segments32and the position adjustment of the tip ends40at the time of the bending with reference toFIGS. 5 to 8.FIG. 5illustrates a schematic configuration of a bending device60for bending the conductor segments32. As illustrated inFIG. 5, the bending device60includes: a stator core fixing portion62configured to fix the stator core22in which the conductor segments32are inserted into the slots30; an annular jig64configured to bend the conductor segment32; a jig holding portion66configured to rotate the jig64and move the jig64up and down in the axial direction; and a controlling portion68configured to control operations of the stator core fixing portion62, the jig64, and the jig holding portion66.

Note that the configuration of the bending device60other than the jig64is similar to a configuration of a well-known bending device (see Japanese Patent Application Publication No. 2006-136082 (JP 2006-136082 A)), and therefore, a description thereof is omitted. The following specifically describes the jig64configured to bend the conductor segments32.

FIG. 6is a partial enlarged view when the jig64is viewed from a side surface. As illustrated inFIG. 6, the jig64includes a first jig70configured to bend the conductor segments32U1,32V1,32W1, and a second jig72configured to bend the conductor segments32U2,32V2,32W2. The first jig70includes protrusions71configured to bend the conductor segments32U1,32V1,32W1. The protrusions71are disposed at distances P20corresponding to arrangement positions of the conductor segments32U1,32V1,32W1. The distance P20is twice as large as a distance P10, and the distance P10is the same distance as the distance P1illustrated inFIG. 3. Further, the protrusion71includes: a tilting surface71aconfigured to abut with the tip end40of the conductor segment32and to tilt and bend the conductor segment32in the circumferential direction; and a position defining surface71bconfigured to define a position of the tip end40of the conductor segment32after the conductor segment32is bent.

The second jig72has an annular shape having a diameter smaller than the first jig70, and is disposed inside the first jig70. As illustrated inFIG. 7, an inner peripheral surface of the first jig70slidably makes contact with an outer peripheral surface of the second jig72. Further, the second jig72has a shape similar to the first jig70. Protrusions73of the second jig72are disposed so as to correspond to arrangement positions of the conductor segments32U2,32V2,32W2. A disposition distance is the same as the protrusions71, and the protrusions73are disposed at the distances P20. The distance P20is twice as large as the distance P10, and the distance P10is the same distance as the distance P1illustrated inFIG. 3. On this account, the protrusions71,73are disposed at the same distance P10as the distance P1illustrated inFIG. 3.

The jig holding portion66that holds the first jig70and the second jig72includes respective actuators configured to rotationally drive the first jig70and the second jig72, so as to rotationally drive the first jig70and the second jig72, individually. These actuators are controlled by the controlling portion68, and can reversely rotate the second jig72after the rotation of the first jig70, or can stop the rotation of the second jig72during the rotation of the first jig70, for example. Note that operations of the first jig70and the second jig72will be describe later more specifically.

Next will be described a manufacturing process of the stator20with reference toFIG. 8. A manufacturing apparatus for manufacturing the stator20includes: an insertion device configured to insert the conductor segments32into the stator core22; the bending device60configured to bend the conductor segments32projecting from the slots30; and a welding device configured to join the tip ends40of the bent conductor segments32thus bent. As illustrated inFIG. 8, the manufacture of the stator20includes: an insertion step (step S10) of inserting the conductor segments32into the slots30of the stator core22; a bending step (step S20) of bending the conductor segments32projecting from the slots30, following the insertion step; and a joining step (step S30) of joining the tip ends40of the conductor segments32thus bent.

In step S10, the conductor segments32illustrated inFIG. 2are inserted into the slots30of the stator core22from the first axial end side. After the conductor segments32are inserted into all the slots30, the stator core22is carried into the bending device60.

In step S20, the stator core22carried into the bending device60is fixed with the stator core fixing portion62. After the fixation of the stator core22, the jig64is moved down, and the protrusions71of the first jig70and the protrusions73of the second jig72are brought into contact with the tip ends40of their corresponding conductor segments32. From this state, the first jig70and the second jig72are moved down and rotated so as to tilt and bend the conductor segments32.

This bending operation will be described with reference toFIG. 9.FIG. 9illustrates the bending operation of the conductor segment32U1and the conductor segment32U2adjacent to the conductor segment32U1. As illustrated inFIG. 9, the protrusion71is moved down and rotated from a position H1awhere the protrusion71abuts with the tip end40U1of the conductor segment32U1, such that the protrusion71moves through the position H1a, a position H2a, and a position H3a, so that the tilting surface71aof the protrusion71presses the tip end40U1so as to press down (bend) the conductor segment32U1. When the protrusion71moves to a position H4a, the tip end40U1is separated from the tilting surface71aand abuts with the position defining surface71b. Further, when the protrusion71moves from the position H4ato a position H5a, a position of the tip end40U1in the circumferential direction is defined by the position defining surface71bof the protrusion71. Note that a movement locus at the time when the protrusion71moves from the position H1ato the position H5ais indicated by a reference sign K1. Further, the movement locus K1is extracted to be illustrated in a characteristic view.

In the meantime, inFIG. 9, similarly to the protrusion71, the protrusion73presses down (bends) the conductor segment32U2in conjunction with the moving-down and rotating of the protrusion71. That is, the protrusion73moves in a similar manner to the protrusion71from a position H1bto a position H5b. After the operation of the protrusion71is finished, the protrusion73rotates reversely from the position H5bto a position H6b. A reverse rotation angle is an angle corresponding to a distance L1. The distance L1is the same distance as the distance L1illustrated inFIG. 3. That is, the protrusion73pushes back the tip end40U2only by the distance L1, so as to adjust a position of the tip end40U2. Since the tip end40U2is pushed back by the distance L1, the tip end40U2approaches the tip end40U1. Further, a movement locus at the time when the protrusion73moves from the position H1bto the position H6bis indicated by a reference sign K2, and the movement locus K2is extracted to be illustrated in a characteristic view.

As apparent from a comparison between the movement locus K1of the protrusion71and the movement locus K2of the protrusion73, the protrusion73reversely rotates independently from the protrusion71after the operation of the protrusion71is finished. Due to the reverse rotation, the tip end40U2is pushed back only by the distance L1and approaches the tip end40U1, as illustrated inFIG. 3. As a result, as illustrated inFIG. 4, a distance between the tip end40U1and the tip end40U2in the same phase is narrowed and a distance between the tip end40U2and the tip end40V1in different phases is widened, so that the relationship of the tip-end distance G1a>the tip-end distance G2ais established.

Further, another conductor segment32U1in the same phase to be joined to the tip end40U1of the conductor segment32U1is bent by another jig64in a reverse direction along the circumferential direction, so that the tip ends40of the conductor segments32in the same phase are placed at a position where they abut with each other. Other conductor segments32V1,32V2,32W1,32W2are also bent in the same manner.

In step S30, contacting parts between the tip ends40U1of the conductor segments32U1in the same phase are irradiated with laser so that those parts are welded to each other. Laser welding can perform heating locally, and therefore, even if the tip ends are placed closely, only desired tip ends40U1can be welded. As a result, the plurality of conductor segments32U1can be connected electrically. By welding the tip ends40of all the conductor segments32, the stator coil24is finished.

As such, in the circumferential direction and in the axial direction, a distance between the tip ends40in the same phase can be narrowed and a distance between the tip ends40in different phases can be widened. Further, a creepage distance between the tip ends40in different phases can be also increased. As illustrated inFIG. 4, for example, a distance (a different-phase distance) in the circumferential direction and the axial direction between the tip end40U2and the tip end40V1in different phases can be made larger than a distance (a same-phase distance) between the tip end40U1and the tip end40U2in the same phase. This makes it possible to improve an insulating property of the tip ends40in different phases between which a potential difference is large. As a result, it is not necessary to coat the tip ends40with the insulation resin, which does not require an insulation step of the tip ends40, thereby making it possible to restrain an increase in cost.

Further, similarly to the tip ends40, in the circumferential direction and in the axial direction, a distance between the conductor segments32in the same phase can be narrowed and a distance between the conductor segments32in different phases can be widened. This makes it possible to improve an insulating property between the conductor segments32in different phases. Further, the coating of the insulation resin that coats the conductor segments32can be reduced in thickness, thereby making it possible to reduce a used amount of the insulation resin.

Further, the tip ends40intersecting at the time when the linear parts50of the conductor segments32are bent are welded by laser, thereby making it is possible to shorten a length of the stator20in the axial direction. This consequently makes it possible to downsize the stator20while securing the insulating property of the tip ends40and the conductor segments32.

Further, by bending the conductor segments32by the bending device60using the jig64, it is possible to manufacture, in a single step, a segment coil in which the distance between the tip ends40in the same phase is small and the distance between the tip end40in different phases is large. On this account, it is possible to manufacture the stator20having an improved insulating property of the tip ends40with manufacture efficiency at a restrained manufacturing cost.

Next will be described another bending operation of the conductor segments32with reference toFIG. 10. Similarly toFIG. 9,FIG. 10illustrates a bending operation of the conductor segment32U1and the conductor segment32U2adjacent to the conductor segment32U1. InFIG. 10, a bending operation of the conductor segment32U1is the same as the bending operation of the conductor segment32U1illustrated inFIG. 9, and therefore, a description thereof is omitted. With reference toFIG. 10, a bending operation of the conductor segment32U2by the protrusion73will be described.

InFIG. 10, similarly to the protrusion71, the protrusion73presses down (bends) the conductor segment32U2in conjunction with the moving-down and rotating of the protrusion71. In the bending operation, an operation from a position H1cto a position H4cis the same as the operation from the position H1bto the position H4billustrated inFIG. 9.

The protrusion73stops a rotative motion at the position H4cand stays at the position H4c. A moving-down operation is kept performed, so that the protrusion73moves from the position H4cto a position H5calong the axial direction. At the position H4c, the tip end40U2abuts with the position defining surface73bof the protrusion73, so that the tip end40U2moves to the position H5ctogether with the protrusion73.

The position H4cand the position H5care a position short from the position H5ain the circumferential direction only by a distance L1, and this distance L1is the same distance as the distance L1illustrated inFIG. 3. That is, the tip end40U2stays at a position short from the tip end40U1only by the distance L1. Because of this, the tip end40U2approaches the tip end40U1. Further, a movement locus at the time when the protrusion73moves from the position H1cto the position H5cis indicated by a reference sign K3, and the movement locus K3is extracted to be illustrated in a characteristic view.

As apparent from a comparison between the movement locus K1of the protrusion71and the movement locus K3of the protrusion73, the protrusion73stops rotating during the rotation, so that its movement in the circumferential direction is stopped and the protrusion73stays at this position. Since the protrusion73stays, the tip end40U2stays at a position short from the tip end40U1only by the distance L1and approaches the tip end40U1as illustrated inFIG. 3. As a result, as illustrated inFIG. 4, the distance between the tip end40U1and the tip end40U2in the same phase is narrowed and the distance between the tip end40U2and the tip end40V1in different phases is widened, so that the relationship of the tip-end distance G1a>the tip-end distance G2ais established.

Even by such a bending operation of the conductor segments32, the distance between the tip ends40in the same phase can be narrowed and the distance between the tip ends40in different phases can be widened in the circumferential direction and in the axial direction. For example, as illustrated inFIG. 4, the distance (the different-phase distance) in the circumferential direction and the axial direction between the tip end40U2and the tip end40V1in different phases can be made larger than the distance (the same-phase distance) between the tip end40U1and the tip end40U2.

Note that the configuration in which intersecting parts that intersect with each other at the time when the conductor segments32are bent are joined by welding has been described, but the configuration of the present disclosure can be also applied to a configuration in which linear parts obtained by axially extending the conductor segments32from the intersecting parts are joined by welding.