Stator manufacturing method

Abstract: A method for manufacturing a stator of a motor having a coil (10) wound on a ring-shaped core having a plurality of slots. The coil (10) is first preformed into a chevron-shape before being mounted on the core so that the chevron-shaped coil (10) comprises front coil end portions (11) positioned within the inner diameter of the core, slot coil portions (12) positioned at the diameter of the slots and having substantially the same configuration as the slots, rear coil end portions (13) positioned between the slot coil portions (12), and transition coil portions (14) positioned between the front coil end portion (11) and the slot coil portions (12). Thus preformed coil is inserted into the core from its end face and the front coil end portions (11) are bent toward the outside of the inner diameter of the core.

Description: BACKGROUND OF THE INVENTION This invention relates to a stator manufacturing method according to the preamble of the claim as is known from JP-62-14 79 32 and discussed below with reference to Fig. 10-16. Fig. 10 is an overall perspective view of a coil 1 to be wound on a core of a conventional vehicular ac generator. The coil 1 is in the form of the so-called star-shaped coil in which a conductor is wound into a ring by a required times and provided with projections and recesses by the number corresponding to the number of poles. Fig. 11 is a core 3 having formed in its inner diameter side a plurality of slots 2. When the coil 1 is inserted into these slots 2, a stator 4 illustrated in Fig. 12 is obtained. Figs. 13 to 16 are views illustrating the steps of inserting the coil 1 into the slots 2, in which 5 is a coil guide holder, 6 are coil guides supported by the coil guide holder 5, and 7 is a coil pusher slidable for a reciprocating motion along the coil guides 6. In order to insert the coil 1 into the slots 2, the coil 1, which was prepared by winding an electric conductor into a ring having a necessary number of turns and formed to have a radial projections and grooves by a number corresponding to the pole number, is mounted to the coil guides 6 (see Fig. 13). In this state, the coil 1 is lift up by the coil pusher 7 so that the coil 1 is brought into contact with the core 3 and deformed (see Fig. 14). By further lifting up the coil pusher 7, the coil 1 is completely inserted within the slots 2 (see Fig. 15). Thereafter, the coil pusher 7 is lowered to the original position (see Fig. 16). DE-C-742 444 discloses a method for manufacturing a stator, in which a coil is assembled on a slotted annular stator core by inserting it axially into the core from one end thereof. Before the core is inserted, it is preformed into the shape required after insertion. In particular, according to the known method the coil is pre-formed and inserted axially into the stator core on a cylindrical former having an outer diameter corresponding to the stator bore. Axially directed slits are provided in the leading edge of the cylinder at circumferential positions corresponding to the stator core slots. The coil is lap wound on the former so that windings pass through the slits to form front coil end portions lying inside the cylinder, while coil portions destined for the stator slots lie on the outside of the cylinder, passing around removable guide bolts at the trailing end thereof. According to the conventional stator manufacturing method for a vehicular a.c. generator stator, during the insertion of the coil 1 into the slots 2, the coil 1 is deformed while it is being hit and rubbed against the core 3, the coil guides 6, coil pusher 7 and the like under an insertion pressure, so that the insulation coating of the coil 1 and the core 3 may be damaged especially when the stator 4 having a high space factor coil is to be manufactured. Also, even when the coil 1 is aligned to the core 3 before insertion, it is in a misaligned state when inserted and the slot coil portion and the coil end portion are not in alignment, so that the space factor of the coil with respect to the core, the space efficiency and the cooling efficiency are disadvantageously lowered. The stator manufacturing method of the present invention has been made to solve the above problem and has as its object the provision of a stator manufacturing method which can manufacture a stator which has high coil space factor with respect to the core, high space efficiency and high cooling efficiency. SUMMARY OF THE INVENTION Accordingly, the initially defined stator manufacturing method of the present invention comprises the steps according to the characterizing portion of the claim. According to the present invention, the coil is formed into a configuration corresponding to the coil configuration inserted in the core, and the coil is inserted into the core. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more readily apparent from the following detailed description of the preferred embodiment of the present invention taken in conjunction with the accompanying drawings, in which: Fig. 1 is an overall perspective view of one embodiment of the present invention; Fig. 2 is a plan view of Fig. 1; Fig. 3 is a view illustrating the manner in which the coil is pressure-formed; Figs. 4 to 6 are views illustrating the rear coil end where the first phase coil, the second phase coil and the third phase coil are inserted into the respective core slots; Fig. 7 is a view illustrating the state in which the coil of Fig. 1 is inserted from the core end face; Fig. 8 is a sectional view illustrating the core of another embodiment of the present invention; Fig. 9 is a sectional view illustrating the core of a still another embodiment of the present invention; Fig. 10 is a perspective view of one example a conventional coil; Fig. 11 is a perspective view of the core; Fig. 12 is a perspective view of the stator in which the coil is wound on the core; and Figs. 13 to 16 are views illustrating the steps of inserting the coil into the core. DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described in conjunction with the drawings. Fig. 1 is a perspective view of one embodiment of a coil mounted to a vehicular ac generator core and Fig. 2 is a plan view of Fig. 1, the same components as those in Figs. 10 to 16 are designated by the same reference numerals and their description is omitted. In the figures, 10 is a coil to be inserted into the core 3, and the coil 10 is pre-formed from the star-shaped coil 1 into a configuration corresponding to that of the coil inserted in the core 3. 11 are front coil end portions which become front coil ends after the coil 10 is inserted in the core 3 and are positioned inside of the inner diameter of the core 3. 12 is slot coil portions which are disposed within the slots 2 when the coil 10 is mounted to the core 3. The slot coil portions 12 are positioned at the diameter of the slots 2 of the core 3 and configured in correspondence with the slots 2. 13 are rear coil end portions disposed between the slot coil portions 12, and 14 are transition coil portions disposed between the front coil end portions 11 and the slot coil portions 12. Fig. 3 is a view illustrating the manner in which the coil 10 is pre-formed, wherein 20 is a pressure-forming jig having a configuration similar to that of the slots 2 of the core 3, and 21 is a pressure punch for pressing the coil contained within the grooves 22 formed in the pressure-forming jig 20 with a static pressure. The coil 10 is formed by the pressure-forming jig 20 and the pressure punch 21 in several steps so that the electrically insulating coating on the coil 10 is never damaged during this forming operation. Figs. 4 to 6 illustrate the state of the rear coil end portions 13 when the first, the second and the third phase coils 10, respectively, are inserted into the core 3. The rear coil end portions 13 of the respective phase have different configurations so that the insertion of each phase coil 10 is obstacled. The chevron-shaped coils 10 of as above-formed are inserted into the core 3 from its end face. At this time, as illustrated in Fig. 7, the slot coil portion 12 is positioned at the same diameter as the slots 2 during the entire insertion process, and the front coil end portions 11 are inside of the inner diameter of the core 3, and in this situation, the coil end portions 11 are forced to override the teeth 8 to be inserted into the core 3. Also, the transition coils 14 pass through the slot opening 9 of the core 3 in the state where they are stacked in a vertical position. Thereafter, the front coil end portions 11 are deformed outwardly of the inner diameter of the core 3 and the winding operation of the coil 10 onto the core 3 is completed. The above deformations of the coil conductors are carried out with relatively small forces, so that no electrical insulation on the front coil end portions 11 is destroyed. Figs. 8 and 9 are sectional views illustrating the stator to which coil conductors 30 of a rectangular cross-section are inserted into the slot 2 by the same process as that described above. While the present invention has been described in terms of an embodiment of a stator manufacturing method for a vehicular ac generator, the present invention can be equally applied to an ac generator stator for the purpose other than vehicles. As has been described, according to stator manufacturing method of the present invention, since the coil is pre-formed into a configuration corresponding to that after it is inserted into the core and this pre-formed coil is inserted into the coil, the coil is not subjected to deformation even when it is inserted into the core and the electrical insulating coatings on the coil and the core are not damaged. Also, since the slot coil portions are inserted into the core slots with their alignment is maintained, the space factor of the coil in the slots is high and the alignment is maintained at the front and the rear coil end portions, so that the high space factor and the cooling efficiency are advantageously obtained.

Claims: A stator manufacturing method in which a coil (10) is assembled on a ring-shaped core (3) having a plurality of slots (2) defined between pole teeth (8) in its inner diameter side, comprising the steps of: winding a conductor into a ring-shaped coil (10) having the required number of turns; forming said ring-shaped coil into a star shape with the number of projections and recesses corresponding to the required number of poles; and inserting said coil (10) into said core (3) from its end face; characterized by the steps of: pre-forming said star-shaped coil (10) into a chevron shape before inserting said coil into said core (3), said chevron shape corresponding to the required shape of the coil (10) after insertion into the core (3), said chevron-shaped coil comprising slot coil portions (12) positioned at the diameter of said slots (2) and having substantially the same configuration as said slots (2), front coil end portions (11) positioned within the inner diameter of said core (3) so as not to interfere with the pole teeth (8) during insertion of said slot coil portions (12), rear coil end portions (13) positioned between said slot coil portions (12), and transition coil portions (14) positioned between said front coil end portions (11) and said slot coil portions (12); and after inserting said coil (10) deforming said front coil end portions (11) toward the outside of the inner diameter of said core (3).

Inventors: TAJI RYOICHI, TAKIZAWA TAKUSHI, TAJI, RYOICHI, TAKIZAWA, TAKUSHI, TAJI, RYOICHI, C/O MITSUBISHI DENKI K.K., TAKIZAWA, TAKUSHI C/O MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1991
Main classification: H02K15
IPC codes: H02K15