Method for making a coil piece onto a core of rotary electric machine

A method for mounting a coil onto a stator for a rotary electric machine. The method includes forming a coil piece by winding wire having a flat cross section into a single row lamination state including wire layers that are aligned along a line that is perpendicular to flat surfaces of the wire. The coil piece is formed so that a first portion to be inserted in the slot and a second portion that is not inserted in the slot appear alternately along the coil piece. The method also includes displacing the wire layers at the first portion from one another to change the single row lamination state to a connectively laminated stat e in which the wire layers at the portion to be inserted in the slot each adjacent pair of the wire layers partially overlap with respect to a direction perpendicular to the flat surfaces of the wire. The method further includes inserting the wires of the first portion into the slot, by passing each of the wire layers through the opening of the slot successively from the wire layer at the top of the lamination and displacing each of the wire layers at the first portion from each other.

BACKGROUND OF THE INVENTION

The present invention relates to a rotary electric machine and a method for mounting a coil on a core for a rotary electric machine.

A typical rotary electric machine such as a motor and a generator is formed by disposing a coil onto a core that is used for a rotary electric machine, in which a stator (or a rotor) is formed of laminated steel sheets. For example, when a stator core is used, teeth are formed in the inner circumferential surface (or outer circumferential surface) of the stator core and a stator is formed by inserting a coil in slots formed between the teeth. The coil is formed from a conductive wire insulated with a coating. Conventionally, wires having a circular cross-section have been used. However, wires having a flat cross-section such as oval or rectangular have come into use as described in Japanese Laid-Open Patent Publication No. 10-66314 to improve the output characteristics of the rotary electric machine by increasing the density (lamination factor) of the coil in each slot. In this case, the number of coil side wires inserted in each slot may be increased in order to optimize the operating condition of the rotary electric machine.

Japanese Laid-Open Patent Publication No. 10-66314 discloses coil pieces formed before being mounted onto the stator. Each coil piece is formed by winding wire having rectangular cross section, such that coil sides, each of which is a section inserted in a slot opening, and coil ends, each of which is not inserted in the slot, are arranged to appear alternatively as the wire is wound in a spiral form. The coil is mounted on the stator core by inserting the coil side wires into the corresponding slot through an open end of the slot. Each coil piece is formed into a shape in which adjacent coil side wires (and adjacent coil end wires) abut each other on the narrower sides of the rectangular cross section of the wire and the wider sides of the wire side faces together form a substantially planar surface.

According to the method for mounting a coil described in Japanese Laid-Open Patent Publication No. 10-66314, the coil pieces connected by the connecting wire are formed in advance with a twisted portion. One coil side of each of two coil pieces are then inserted into one slot successively such that two coil pieces are disposed next to each other in the circumferential direction of the stator core. That is, the coil side wires of each coil piece inserted in the slot overlap along the radial direction of the stator core in the slot. Therefore, the coil side wires of the second coil piece are laminated consecutively onto the coil side wires of the first coil piece in the radial direction of the stator core.

The above described coil can permit the coil side wires to be inserted in the slots without being hindered, even if the open end of each slot is somewhat narrowed by a projection extending toward the circumferential direction of the stator from the distal end of each tooth as described in Japanese Laid-Open Patent Publication No. 2003-204647.

However, when the coil pieces of the Japanese Laid-Open Patent Publication No. 10-66314 are used in some slots where the open end of each slot in harrowed, the coil side wires of the coil piece that has earlier been inserted in the slot might block the opening of the slot from inside depending on the position and shape of the openings. This might obstruct insertion of the subsequent coil pieces into the slot.

Therefore, according to the method for mounting a coil described in Japanese Laid-Open Patent Publication No. 10-66314, the number of coils that are inserted in each slot cannot be increased in some positions where the opening of each slot is narrow. If so, as the lamination factor of the coils in each slot cannot be improved, the output characteristics of the rotary electric machine cannot be improved as desired.

Japanese Laid-Open Patent Publication No. 2003-204647 discloses a number of U-shaped coil pieces, each coil piece being inserted in the slot from the axial direction of the stator core such that both leg portions of each coil piece (coil sides) are laminated in the radial direction of the stator core while sandwiching one of the teeth from both sides. In this manner, the coil pieces are temporarily mounted in the slots. Subsequently, the distal ends of the leg portions (coil ends) of the coil pieces that project axially outward from the slots are connected by TIG welding or the like such that the laminated coil pieces are connected in a spiral form. As a result, a coil is formed.

According to the method for mounting the coil described in Japanese Laid-open Patent Publication No. 2003-204647, various types of U-shaped coil pieces with various sizes are prepared. Leg portions (coil sides) of the coil pieces are successively inserted in a single slot such that the leg portions are sequentially laminated in the circumferential direction of the stator core.

The method for mounting the coil described in Japanese Laid-Open Patent Publication No. 2003-204647 reduces the risk that the legs (coil sides) of the previously mounted coil pieces will obstruct other coil pieces that are subsequently mounted (inserted). However, the method requires a complicated operation for connecting the distal ends of the legs of the coil pieces through welding or the like after temporarily mounting the coil pieces to the slots. This reduces production efficiency.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide a rotary electric machine and a method for mounting a coil of a core for a rotary electric machine that reliably ensures the lamination factor for the coil in slots and improves the output characteristics of the rotary electric machine without decreasing production efficiency.

In order to achieve the above objective, the present invention provides a method for mounting a coil piece onto a core of a rotary electric machine. The core has a plurality of slots each having an opening. The method includes: repeatedly winding wire having a flat-cross-section so that the wire forms a plurality of wire layers that are laminated in a single row, thereby forming the coil piece in which the wire layers are in a first laminated state, the first laminated state referring to a state in which the plurality of wire layers are aligned along a line that is perpendicular to flat surfaces of the wire, wherein the coil piece has first portions each inserted into one of the slots and second portions that are not inserted into the slots, the first portions and the second portions are arranged alternately along a direction in which the wire extends; shifting the state of the first portions from the first laminated state to a second laminated state by displacing the wire layers in each first portion relative to each other along the flat surfaces of the wire, the second laminated state referring to a state in which each adjacent pair of the wire layers partially overlap with respect to a direction perpendicular to the flat surfaces of the wire; inserting the first portions in the second laminated state into the slots by causing each first portion to pass through the opening of the corresponding slot in an order from the head of the laminated wire layers; and returning the first portions in the slots from the second laminated state to the first laminated state by displacing the wire layers in each first portion relative to each other.

The present invention also provides a rotary electric machine including a core having a plurality of slots, and a coil piece mounted onto the core. The coil piece is formed by repeatedly winding wire having a flat-cross-section so that the wire forms a plurality of wire layers that are laminated in a single row. The coil piece has first portions each inserted into one of the slots and second portions that are not inserted into the slots. The first portions and the second portions are arranged alternately along a direction in which the wire extends. The wire layers in each first portion are laminated while being aligned along a direction intersecting the depth of the corresponding slot.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A method for mounting a coil to a stator core of a motor10according to one embodiment of the present invention will how be described with reference toFIGS. 1 to 8. The motor10is one type of a rotary electric machine.

FIG. 1shows a part of a rotary electric machine, which is the motor10in this embodiment. As shown inFIG. 1, a core for a rotary electric machine, a stator core11in this embodiment, has a cylindrical core body12formed of laminated steel sheets. Teeth13project radially inward from the inner circumferential surface of the core body12with an equal pitch in the circumferential direction of the stator. Each tooth13has a projection15at its distal end. Each projection15extends along a direction opposite to the rotation direction R of a rotor core14shown by a chain double-dashed line inFIG. 1so that the teeth13are L-shaped. A slot16is formed between the adjacent teeth13extending along the axial direction of the core body12. In the preferred embodiment, the stator core11is a straight core in which the slots16extend along to the axial direction.

Each slot16has an opening17, which is defined by the distal ends of the teeth13located adjacent to each other to sandwich the slot16from the circumferential direction. The opening17of each slot16is narrower than the circumferential width of the slot16by the length of the projection15, which extends from the distal end of the corresponding tooth13along the direction opposite to the rotation direction R of the rotor core14. A rectangular wire18having a flat cross-section formed of an insulated conducting wire is inserted in the slots16via the openings17. The width of the wider surface of the wire18is greater than the width (circumferential width) of each opening17and the narrower end face of the rectangular wire18is smaller than the width of the opening17.

The rectangular wire18is mounted in the slots16via insulating papers19through distributed winding. The stator core11therefore functions as a stator for the motor10. As shown inFIG. 1, in the preferred embodiment, the rectangular wire18is mounted in the slots16such that the rectangular wire18is brought into a single row laminated state in the circumferential direction of the stator core11. Further, three rows (several rows) of the single row laminated state, a first laminated state, of the rectangular wire18that are in phase are formed in the same slot16along the depth direction of the slot16.

A procedure for mounting the rectangular wire18on the stator core11and various devices used in the mounting operation will now be described.

When mounting the rectangular wire18on the stator core11, the rectangular wire18, which is wound about a bobbin or the like (not shown), is wound several times in a single row in advance using a coil piece forming device21as shown inFIG. 3. Accordingly, a coil piece (or a coil preform)20as shown inFIG. 2is formed. The coil piece20has coil sides (slot inserted sections)22and coil ends (slot non-inserted sections)23, which are alternately and continuously arranged in a single row laminated state. The coil sides22are straight and will be inserted in the slots16when the rectangular wire18is mounted on the stator core11. The coil ends23are curved and will not be inserted in the slots16. More specifically, the coil piece20is formed into the single row laminated state in which the wide surfaces of the rectangular wire18serve as laminated surfaces. In the winding direction of the rectangular wire18, three or more (six in this embodiment) laminated bundles of the coil sides22, which are in the single row laminated state, are provided. Laminated bundles of the coil ends23, which are also in the single row laminated state, are each located between the bundles of coil sides22.

In the preferred embodiment, three coil pieces20(only one of which is shown inFIG. 2) are formed and are connected to one another with a connecting wire24. The coil piece20shown inFIGS. 2 and 3is a first row (first) coil piece20A, which is mounted in the innermost sections of the slots16. The rectangular wire18is wound ten times into the single row laminated state. A second row (second) coil piece20B (seeFIG. 1), which is mounted at the second innermost row in the slots16, is formed by winding the rectangular wire18nine times into the single row laminated state. A third row (third) coil piece20C (seeFIG. 1.), which is mounted at the third row from the innermost sections of the slots16(or at the section closest to the opening17), is formed by winding the rectangular wire18eight times into the single row laminated state.

As shown inFIG. 3, the coil piece forming device21has a circular substrate25and a three-forked block27, which is secured Lo the substrate25with screws26. The three-forked block27is secured to the substrate25such that the branch point of the three-forked block27is aligned with the center of the substrate25. Three plate-like arms28extend straight and radially outward from the branch point at angular intervals of 120 degrees. The plate-like arms28are formed such that the height (thickness) of each plate-like arm28from the surface of the substrate25is greater than or equal to the width of the wide surface of the rectangular wire18.

As shown inFIG. 3, sections of the coil piece20that correspond to the coil sides22are laminated in a single row along the straight side surfaces of the plate-like arms28by winding the rectangular wire18about the plate-like arms28. In addition, sections corresponding to the coil ends23of the coil piece20arc laminated in a single row along arcuate distal end faces and concave proximal branch surfaces of the plate-like arms28by winding the rectangular wire18about the plate-like arms28. That is, the coil piece20includes three pairs of bundles of the coil sides22(six bundles of the coil sides22) in the single row laminated state and six bundles of the coil ends23in the single row laminated state. Each pair of bundles of the coil sides22includes left and right bundles of the coil sides22, which are parallel to each other. The coil ends23connect the three pairs of bundles of the coil sides22(six bundles of the coil sides22) with a certain curvature.

The coil piece20that has been wound as shown inFIG. 3is still flat where the coil sides22and the coil ends23abut against the substrate25of the coil piece forming device21. Therefore, after the coil piece20has been wound to the coil piece forming device21, the coil piece20that is flat is removed upward from the three-forked block27. The three pairs of bundles of the coil sides22(six bundles of the coil sides22) are then lifted such that the bundles of the coil sides22that form a pair are maintained to be substantially parallel to each other. That is, the three pairs of the coil sides22are lifted while the curved sections of the three of the six bundles of the coil ends23formed along the proximal branch surfaces of the plate-like arms28are held as base portions for lifting. As a result, the coil piece20that is brought into a lifted state as shown inFIG. 2is formed. After that, the coil piece20is inserted in the slots16of the stator core11using a coil side holding device (first connectively laminated state holding device)30shown inFIG. 4.

The coil side holding device30includes a columnar main body30a, which is selectively fitted in the core body12of the stator core11. Groove-like guide passages32, the number of which is the same as the number of the bundles of the coil sides22of the coil piece20, that is, six in this embodiment, are formed in the outer circumferential surface of the main body30a(the section corresponding to the inner circumferential surface of the core body12) along the radial direction of the main body30a. Each guide passage32has a passage opening31the size of which corresponds to that of the opening17of each slot16. The stator core11is a straight core in which the slots16are formed along the axial direction of the stator core11. Therefore, the entire length of the guide passages32and the passage openings31defined in the outer circumferential surface of the main body30aextend along the axial direction of the columnar main body30aso that the guide passages32correspond to the shape of the slots16(and its openings17).

When inserting the coil sides22of the coil piece20to the slots16, the coil sides22are temporarily accommodated in the guide passages32of the coil side holding device30(the main body30a) as shown inFIG. 5in the preceding step. Next, the coil side holding device30(main body30a) is fitted in the stator core11(the core body12) as shown inFIG. 6. The passage openings31of the guide passages32are then aligned with the openings17of the slots16into which the coil sides22that are temporarily accommodated in the guide passages32will be inserted.

FIGS. 7(a) to7(f) are views explaining changes in the laminated state and the movement manner of the coil sides22that are surrounded by a chain double-dashed line inFIG. 6when the coil sides22are inserted (mounted) in the slots16using the coil side holding device30and the like. A procedure for inserting each bundle of the coil sides22in the corresponding slot16by bringing the coil sides22into a connectively laminated state, that is the second lamination state shown inFIGS. 7(b), and7(c), from the single row laminated state (the state shown inFIG. 7(a)) and then returning the coil sides22to the original single row laminated state will now be described.

When the coil piece20is in the lifted state as shown inFIG. 2, each bundle of the coil sides22is in the single row laminated state in which the rectangular wires18(the number of which is ten in the case with the first row coil piece20A shown in FIG. (7a)) are laminated in a single row with the wide surfaces serving as the laminated surfaces as shown by a cross-sectional view inFIG. 7(a). As described above, the width of the wide surface of each coil side22, which is the laminated surface, is greater than the width of each opening17. As is obvious fromFIG. 7(a), the entire length of the bundle of the coil sides22in the lamination direction of the single row laminated state is even greater than the width of the wide surface. Since the coil sides22cannot pass through the opening17of the corresponding slot16in the single row laminated state, the coil sides22are changed to the following laminated state from the single row laminated state.

That is, as shown inFIG. 7(b), the coil sides22in the single row laminated state are displaced with respect to one another such that the coil sides22are in the connectively laminated state in which the coil sides22that are adjacent to each other in the lamination direction are substantially parallel to each other and partially contact each other as viewed in the cross-sectional view. At this time, the coil sides22in the connectively laminated state may be sandwiched from both the left and right sides, which is a direction that intersects with, or that is perpendicular to, the connecting direction of the coil sides22, using a pair of left and right holding members (for example, a pair of long plates or the like)33as shown by a dashed line inFIG. 7(b). When the holding members33are used, each of the coil sides22in the connectively laminated state is quickly and reliably inclined with respect to the connecting direction so that the coil sides22can pass through the opening17of the corresponding slot16. When holding the coil sides22with the holding members33, both ends of the bundle of the coil sides22(the boundaries between the coil ends23and the coil sides22)) are preferably held.

Each bundle of the coil sides22is thus brought into the connectively laminated state shown inFIG. 7(b) by the pairs of holding members33holding both ends of the bundle of the coil sides22. The bundles of the coil sides22are then temporarily accommodated in the guide passages32of the coil side holding device30shown inFIG. 4as described above. After that, each pair of holding members33releases the coil sides22. The coil piece20(20A) is thus brought into a state where the three pairs of bundles of the coil sides22(six bundles of the coil sides22) are accommodated in the guide passages32of the coil side holding device30(main body30a) while maintaining the connectively laminated state. Each bundle of the coil pieces22is held from both left and right sides, which is a direction that intersects with, or is perpendicular to, the connecting direction, by the inner side surfaces32aof the corresponding guide passage32. That is, the coil piece20(20A) is brought into a state as shown inFIG. 5.

In this case, as shown inFIGS. 5,6, and8, a section of each bundle of the coil ends23that is not accommodated in the corresponding guide passage32of the coil side holding device30(main body30a) is twisted such that the outermost layer of the coil ends23intersects with the innermost layer of the coil ends23by the greatest degree. That is, when each bundle of the coil sides22is brought into the connectively laminated state from the single row laminated state, each bundle of the coil ends23that has been in the single row laminated state is also displaced and the laminated state is changed. More specifically, the adjacent coil ends23in the lamination direction are displaced from each other into the connectively laminated state in which the adjacent coil ends23partially contact each other while intersecting each other.

The coil side holding device30(main body30a) that accommodates the bundles of the coil sides22in the guide passages32is then fitted in the stator core11(core body12) as described above to be brought into the state shown inFIG. 6. As shown inFIG. 7(c), an extruding member (square bar or the like)34having substantially the same width as the guide passages32is inserted in the inner section of each guide passage32from the axial direction of the main body30a. Each extruding member34is moved toward the passage opening31from the inner section of the corresponding guide passage32so that the coil sides22in the connectively laminated state in the guide passage32are extruded from the guide passage32. The coil sides22are thus inserted in the corresponding slot16via the passage opening31and the opening17of the slot16successively from the coil side22located at the head of the coil sides22in the connecting direction (in this case, the coil side22closest to the passage opening31).

In the preferred embodiment, the rectangular wire18is designed to be mounted on the stator core11such that the rectangular wire18is in the single row laminated state in each slot16in the circumferential direction of the stator core11. Therefore, the coil sides22that are successively inserted in each slot16in the connectively laminated state must be returned to the original single row laminated state. Therefore, a guide device35as shown inFIG. 7(c) is used to return the laminated state of the coil sides22in the inner section of each slot16from the connectively laminated state to the original single row laminated state. The guide device35is formed of a curved rod material (or plate material and the like). The concave surface of the guide device35functions as a guide portion35a.

As shown inFIG. 7(c), the guide device35is movable along the end face of the stator core11(core body12). While one end of the guide device35(left end as viewed inFIG. 7(c)) is fixed as a fulcrum, the other end is pivoted and displaced such that the coil sides22inserted in the each slot16abut against the guide portion35a. After abutting against the guide portion35athat is pivoted and displaced, the coil sides22move along the guide portion35a. That is, while one end of the guide device35that serves as the fulcrum is located at the inner corner of the slot16, the other end of the guide device35is movable toward the inner section of the slot16from the vicinity of the opening17of the slot16. Thus, the coil sides22that abut against the guide portion35aare guided diagonally inward of the slot16. Therefore, the coil sides22are displaced relative to one another from the connectively laminated state located along the radial direction of the stator core11to the single row laminated state located along the circumferential direction of the stator core11. The displacement causes the coil sides22to be brought into the single row laminated state in which the lamination direction of the coil sides22intersects with the depth direction of the slot16.

When each extruding member34extrudes the coil sides22from the guide passage32into the corresponding slot16and when the coil sides22move along the guide portion35aof the corresponding guide device35after abutting against the guide portion35a, the connecting state (laminated state) of the coil sides22might be separated. Therefore, in the preferred embodiment, as shown inFIG. 8, the intersecting portion of the twist of each bundle of the coil ends23is held by a pair of holding members (round bar or the like)36when the bundles of the coil sides22are inserted in the slots16. Through the above described insertion procedure, the coil sides22are mounted on the stator core11in a state where the coil sides22are arranged close together at the innermost section of each slot16as shown inFIG. 7(d).

However, in this case, the coil sides22are not necessarily in the aligned single row laminated state, but might be in a single row laminated state in which the coil sides22are not aligned. Therefore, in the preferred embodiment, an alignment device37is used to align the coil sides22to be in the original single row laminated state as shown inFIG. 7(e). The alignment device37includes an insertion piece37ahaving a trapezoidal cross-section. The insertion piece37ahas a predetermined length that can be inserted in each slot16(for example, the length that is the same as the axial length of the slot16). One side of the insertion piece37aserves as a flat alignment restrictor37bthat extends straight in the lateral direction that intersects the longitudinal direction of the insertion piece37a.

Therefore, when the insertion piece37aof the alignment device37is inserted in each slot16such that the surface that serves as the alignment restrictor37bfaces the coil sides22from the section of the slot16close to the opening17, the alignment restrictor37babuts against the coil sides22that are not aligned. At this time, the alignment restrictor37bpresses the coil sides22in the depth direction of the slot16that is perpendicular to the lamination direction of the coil sides22. Therefore, when the coil sides22are pressed by the alignment restrictor37bof the alignment device37, the coil sides22are arranged close together at the innermost section of the slot16and aligned into the original single row laminated state.

After the coil sides22of the first row coil piece20A are inserted in each slot16and arranged close together at the innermost section of the slot16in the single row laminated state, the coil sides22of the second and third row coil pieces20B,20C are successively inserted in the same slot16in the same procedure as the first row of coil piece20A. That is, the coil sides22of the second and subsequent rows of coil pieces20B,20C are arranged in front of the coil pieces (for example, the first row coil piece20A) that have been inserted in the slot16earlier such that the single row laminated states of the coil pieces are parallel to one another. As for the alignment device37, the cross-sectional shape of the insertion piece37a(particularly the length along the depth direction of the slot) used for the alignment of the coil sides22of the second and subsequent rows of coil pieces20B,20C is smaller than that of the insertion piece37aused for the alignment of the coil sides22of the first row coil piece20A.

In the preferred embodiment, after the coil sides22of the first to third row coil pieces20A to20C are inserted (mounted) in the same slot16, a wedge38is inserted in the slot16to close the opening17as shown inFIG. 7(f). Thus, the single row laminated state of the coil sides22of the coil pieces20A to20C are formed in three rows (several rows) along the depth direction of the slot16. Therefore, the lamination factor of the rectangular wire18(coil sides22) in each slot16is increased. The number of turns of the rectangular wire18when wound into the single row laminated state differs between the first row coil piece20A and the second row coil piece20B and between the second row coil piece20B and the third row coil piece20C by one turn. Therefore, the coil sides22are arranged in a dense staggered pattern in each slot16as shown inFIG. 7(f), which further increases the lamination factor of tho rectangular wire18(coil sides22) in the slot16.

When the above described coil mounting operation is completed, the coil pieces20(20A,20B,20C) are mounted on the core body12of the stator core11such that six bundles of the coil sides22of each of the coil pieces20(20A,20B,20C) are mounted in every third slot16in the circumferential direction of the core body12as shown inFIG. 1. That is, the coil pieces20(20A,20B,20C) are mounted in the slots16through distributed winding. The coil mounting operation is completed by spreading the laminated bundles of the coil ends.23of the coil pieces20(20A,20B,20C) exposed from the end of the core body12.

The first embodiment has the following advantages.

(1) The coil piece20is formed of a lamination of the rectangular wire18such that the coil sides (slot inserted sections)22, which will be inserted in the slots16, and the coil ends23, which will not be inserted in the slots16alternately appear along the coil. The wires are laminated into the “single row laminated state” where the wires are completely overlapped. Each bundle of coil sides22is inserted in the corresponding slot16after the lamination state is changed from the single row laminated state to the “connectively laminated state” where the wires are partially overlapped. The connectively laminated state is appropriate for the bundle of coil sides22to pass through the opening17of the slot16. The laminated state of the coil sides22is returned to the original single row laminated state from the connectively laminated state in the slot16. The coil sides22can be mounted in the slot16without blocking the opening17.

Therefore, since a subsequent process such as welding is unnecessary after inserting the coil sides22in each slot16, production efficiency is improved. In addition, when the coil sides22are mounted in each slot16, the coil sides22do not block the opening17. Therefore, the coil sides22that are already mounted in the slot16do not restrict other coil sides22from being subsequently inserted in the slot16. Thus, the lamination factor of the rectangular wire18(coil sides22) in the slot16is maintained in a suitable state. As a result, the output characteristics of the motor (rotary electric machine) are improved.

(2) The coil sides22in the single row laminated state are displaced from one another before being inserted in each slot16and brought into the connectively laminated state in which the adjacent coil sides22partially contact each other. The coil sides22brought into the connectively laminated state are held from both sides, which is a direction that intersects with, or is perpendicular to, the length of the overlapped portion of the coil sides22. More specifically, the coil sides22are inclined with respect to the connecting direction so that the coil sides22can pass through the opening17of the corresponding slot16. Therefore, the coil sides22are brought into the connectively laminated state that is appropriate for inserting the coil sides22in the slot16. The rectangular wires18at the coil side22are thus smoothly passed through the opening17and are promptly and easily mounted in the slots16.

(3) When each bundle of the coil sides22is brought into the connectively laminated state in which the adjacent coil side wires partially contact each other, from the single row laminated state, each bundle of the coil end wires is brought into the connectively laminated state in which the adjacent coil ends23intersect and partially contact each other. Therefore, when the coil sides22are inserted in each slot16, the coil sides22are reliably prevented from being separated by holding the twisted portion of the corresponding bundle of the coil ends23. Accordingly, the coil sides22are smoothly inserted in the slot16.

(4) The coil side holding device30includes the guide passages32having the passage openings31the size of which corresponds to the openings17of the slots16. Using the coil side holding device30, the bundles of the coil sides22that are in the connectively laminated state are temporarily accommodated in the guide passages32. After aligning the passage openings31to the openings17of the slots16, the coil sides22are extruded from the guide passages32. Therefore, when inserting each bundle of the coil sides22in the corresponding slot16, the coil sides22are held from both left and right sides in a direction that intersects with, or is perpendicular to, the connecting direction by the inner side surfaces32aof the corresponding guide passage32. Thus, the connectively laminated state is reliably maintained. Accordingly, each bundle of the coil sides22is smoothly inserted in the corresponding slot16while the insertion direction is guided by the associated guide passage32.

(5) Since the core body12of the stator core11is cylindrical and has slots16on the inner circumferential surface of the core body12, the coil side holding device30(first connectively laminated state holding device) has the cylindrical main body30a, which can be fitted in the core body12. The bundles of the coil sides22in the connectively laminated state are accommodated in the guide passages32, which are formed in the outer circumferential surface (the section corresponding to the inner circumferential surface of the core body12) of the main body30a. The main body30ais subsequently fitted in the core body12and the passage openings31are aligned with the openings17. Therefore, the passage openings31of the guide passages32are easily aligned with the openings17when inserting the bundles of the coil sides22that are temporarily accommodated in the guide passages32to the slots16.

(6) Each bundle of the coil sides22inserted in the corresponding slot16in the connectively laminated state abuts against the guide portion35aof the guide device35. The bundle of the coil sides22move inward of the corresponding slot16along the guide device35(guide portion35a) that is shifted. The bundle of the coil sides22are brought into the original single row laminated state from the connectively laminated state. Therefore, each bundle of the coil sides22inserted in the corresponding slot16is smoothly guided to the innermost section of the slot16. In addition, the lamination direction of the coil sides22in the single row laminated state is easily aligned with the circumferential direction of the stator core11.

(7) Furthermore, if the coil sides22in the single row laminated state are not in line at the innermost section of each slot16, the insertion piece37aof the alignment device37is inserted in the slot16. The coil sides22are pressed to be in line by the alignment restrictor37bformed by one side of the insertion piece37a. Therefore, the coil sides22are easily brought into the aligned single row laminated state by the alignment function of the alignment restrictor37bof the alignment device37.

(8) In addition, as for the coil piece20that is in the single row laminated state in which the coil sides22and the coil ends23are alternately arranged, three coil pieces20, which includes the first row coil piece20A, the second row coil piece20B, and the third row coil piece20C, are formed in advance and connected with on another with the connecting wire24. One of the laminated bundles of coil sides22of each coil piece20A to20C is mounted in the same slot16to form a three-row structure of the single row laminated state with the bundles of coil sides22in the depth direction of the slot16. Therefore, the lamination factor of the coil sides22(rectangular wire18) in each slot16is significantly improved.

(9) Furthermore, the number of turns of the rectangular wire18, which defines the number of laminations of the coil sides22, differs by one turn among the laminated bundles of the rows of the coil pieces20A to20C forming the three-row structure of the single row laminated state. Therefore, the bundles of the coil sides22are arranged in a dense staggered pattern in the slot16. Thus, the lamination factor of the coil sides22(rectangular wire18) in each slot16is further improved.

(10) The number of coils and the arrangement of the coils in each slot16are variable by adjusting the number of laminations of the rectangular wire18, which forms the bundles of the coil sides22(coil ends23) in the coil piece20(20A,20B,20C). This adds to the flexibility of the design of the coil mounted in the slots16. Therefore, a mounting manner of the coil that is effective in optimizing the operating condition of the motor10is achieved.

(11) Particularly in the coil piece20(20A,20B,20C), three or more laminated bundles (six bundles in this embodiment) of coil sides22in the single row laminated state are provided in the winding direction of the rectangular wire18. The laminated bundles of coil sides22are mounted in the slots16that sandwich several slots16in between. In this embodiment, the laminated bundles of coil sides22are mounted in every third slot16. Therefore, a coil mounting manner is achieved that is effective when mounting the coil through distributed winding, which is different from the concentrated winding.

The preferred embodiment may be changed as according to the following further preferred embodiments (modified embodiments).

As shown inFIG. 9, the passage openings31of the guide passages32, which are formed in the main body30aof the coil side holding device30, may be formed such that the passage openings31can be inserted in the openings17of the slots16. In this case, when each bundle of the coil sides22is extruded from the associated guide passage32and inserted in the corresponding slot16, the coil sides22are prevented from abutting against the rim of the opening17. Thus, each bundle of the coil sides22is smoothly and reliably inserted (mounted) in-the corresponding slot16.

As shown inFIG. 10, when the bundles of the coil sides22are brought into the connectively laminated state and temporarily accommodated in the guide passages32of the coil side holding device30, the bundles of the coil ends23that have been in the single row laminated state may be brought into the connectively laminated state in which the adjacent coil end wires in the lamination direction partially overlap in a substantially parallel manner. In this case, the displacement directions along which the bundles of coil sides22that are adjacent Lo each other via the coil end23return to the original single row laminated state from the connectively laminated state when being inserted in the slots16are the same. Therefore, the bundles of the coil sides22are smoothly restored to the original single row laminated state.

In a case where the bundles of the coil end23wires are brought into the connectively laminated state in which the coil end23wires are substantially parallel to one another as shown inFIG. 10, the stator core11(core body12) to which the coil side holding device30(main body30a) is inserted should preferably be a stator core11A (core body12A) having the teeth13-with four types of distal ends. That is, the teeth13include T-shaped teeth13a, L-shaped teeth13b, I-shaped teeth13c, and reverse L-shaped teeth13d. Each T-shaped tooth13ahas, at its distal end, projections15, which extend in both circumferential directions of the stator core11A. The L-shaped teeth13bare the same as those in the preferred embodiment. The I-shaped teeth13cdo not have any projection15at the distal ends. Each reverse L-shaped tooth13dhas the projection15extending in a direction opposite to that of the preferred embodiment. The teeth13a,13b,13c, and13dare preferably arranged as shown inFIG. 11. With this structure, when inserting the bundles of the coil side22wires in the slots16, the movement of the bundles of coil side22wires that are adjacent to the bundle of coil end23wires disposed between the coil side wires is symmetrical with respect to a reference line extending along the radial direction of the stator core11A, after being inserted in the slots16.

In a case where the stator core11(core body12) is a core (skew core) in which the slots16are not parallel to the axial direction but are twisted diagonally, the guide passages32, which are formed in the outer circumferential surface of the main body30aof the coil side holding device30, are preferably twisted corresponding to the skew state of the slots16as shown inFIG. 12.

The stator core11(core body12) may be a stator core11B (core body12B) in which all the teeth13are T-shaped and the projections15extend in both circumferential directions from the distal end of each tooth13as shown inFIG. 13. Alternatively, all the teeth13may be reverse L-shaped in which the projections15extend in a direction opposite to that of the preferred embodiment.

When the motor is an outer rotor type, the coil side holding device (second connectively laminated state holding device)30as shown inFIG. 14is preferably used. The coil side holding device (second connectively laminated state holding device)30has the cylindrical main body30a, which is fitted to the outer circumferential surface of the columnar stator core11C (core body12C) in which the slots16are formed. In this case, the passage openings31of the guide passages32are formed in the inner circumferential surface (the section corresponding to the outer circumferential surface of the core body12C) of the main body30a.

In the above embodiment, the number of the coil pieces20, which are connected to one another with the connecting wire24in advance, need not be three, but may be two or more than three. Furthermore, only one coil piece20may be provided. The coil pieces (20A,20B,20C) may be connected to one another with the connecting wire24after the bundles of coil sides22are mounted in the slots16. In this case also, only one connecting wire24is used to connect the coil pieces20in the subsequent process. Since it is not required to connect all coils (rectangular wires18) in the subsequent process, the production efficiency is not decreased.

In the above embodiment, the holding members33,36, the extruding members34, the guide devices35, and the alignment devices37need not be used and their shapes may be changed as required. Furthermore, the holding members33,36, the extruding members34, the guide devices35, and the alignment devices37may be operated manually or mechanically. When forming the coil piece20, the coil piece forming device need not be the one described in the preferred embodiment shown inFIG. 3.

In the preferred embodiment, a core for a rotary electric machine is the stator core11. However, as is applicable from the modified embodiment shown inFIG. 14, a core for a rotary electric machine may be a rotor core. The rotary electric machine need not be a motor but may be a generator. The invention may be applied to a stator core (or a rotor core) of the generator.

In the above embodiment, tile slots16are formed in the inner circumferential surface (or the outer circumferential surface) of the core body12at an equal pitch but may be arranged at an irregular pitch.

In the above embodiment, the width of the wide surface of the rectangular wire18may be smaller than the width of the opening17of each slot16.

When the bundles of the coil sides22are temporarily inserted in the guide passages32of the coil side holding device30, each bundle of the coil sides22need not be in the connectively laminated state in which the coil sides22are parallel to each other in the diagonal state as long as the coil sides22are in the connectively laminated state in which the adjacent coil sides22partially contact each other.

In the above embodiment, the coil side holding device30(main body30A) need not be columnar as shown inFIGS. 4,12as long as the passage openings31of the guide passages32are formed at the section corresponding to the inner circumferential surface of the core body12.

The rectangular wire18may be anything as long as it has a flat cross-section such as a trapezoidal cross-section or an oval cross-section so that a surface that serves as the laminated surface is provided when the rectangular wire is brought into the single row laminated state.