Stator of rotary electric machine and method for making the same

This is a Division of application Ser. No. 09/549,027 filed Apr. 13, 2000 now U.S. Pat. No. 6,400,056. The entire disclosure of the prior application(s) is hereby incorporated by reference herein in its entirety.

This application is based on Japanese Patent Application No. Hei 11-106914 filed on Apr. 14, 1999, the contents of which is incorporated herein by reference.

1. Field of the Invention

The present invention relates to a stator of a rotary electric machine having an improved dielectric strength at an edge of an axial inlet of a slot and a manufacturing method of the same.

2. Description of Related Art

It is known that a construction is disclosed in JP 58-157349A for improving a dielectric strength at an edge of a slot formed on a stator of rotary electric machine. In this prior art, wavy creases are previously formed on a portion of an insulating member where the insulating member contacts an edge of a slot. After that, an end portion of the insulating member extended from the slot is heated and expanded. As a result, easiness for inserting a conductor into the slot is improved, and insulation is maintained by inserting the insulating member to separate the conductor and the edge.

However, in the prior art, a heating and forming die is pressed on the stator core when the end portion is heated and expanded. The insulator is pressed on the edge of the slot, and a thickness is decreased. Therefore, there is a possibility of insulation failure if the conductor is compressed between the die and the edge of the slot and is deformed.

The present invention addresses these drawbacks by providing an improved stator arrangement.

It is therefore an object of this invention to provide a stator having improved dielectric strength at the edge of the slot and a manufacturing method.

According to the present invention, an expanded end is formed on an insulating member. The insulating member is moved toward a side of the expanded end before a conductor is inserted from the expanded end.

Therefore, an easiness to insert the conductor is improved due to the expanded end. An additional damage on the deformation mark is prevented when the conductor is inserted. Therefore, an insulation failure at a deformation mark is prevented.

It is preferred that the deformation mark is positioned in the out of the slot after a conductor is inserted. In this construction of the stator, an additional damage on the deformation mark is prevented during the conductor is inserted. A thickness of the insulating member positioned between an edge of a slot and the conductor is maintained thicker than the thinned deformation mark.

Other features and advantages of the present invention will be appreciated, as well as methods of operation and the function of the related parts, from a study of the following detailed description, the appended claims, and the drawings, all of which form a part of this application. In the drawings:

FIG. 1 is a perspective view showing a stator core and an insulating member of an embodiment of the present invention;

FIG. 2 is a perspective view showing a shape of a conductor inserted in to the stator core;

FIG. 3 is a side view showing an expanding process of the insulating member;

FIG. 4 is a side view showing an expanding process of the insulating member;

FIG. 5 is a side view showing an expanding process of the insulating member;

FIG. 6 is a side view showing an expanding process of the insulating member;

FIG. 7 is a side view showing an expanding process of the insulating member;

FIG. 8 is a side view showing a pushing up process of the conductor;

FIG. 9 is a side view showing a pushing up process of the conductor;

FIG. 10 is a side view showing an inserting process of the conductor;

FIG. 11 is a side view showing an inserting process of the conductor;

FIG. 12 is a side view showing a form after the insertion of the conductor is completed;

FIG. 13 is a sectional view in the circumferential direction of the stator core showing the insulating member and the stator core; and

FIG. 14 is a sectional view in the circumferential direction of the stator core showing the insulating member and the stator core.

An embodiment of the invention will be described with reference to the drawings.

A stator has a cylindrical stator core 1 , a plurality of insulating members 2 and a plurality of conductors 3 . Each insulating member 2 is made of a sheet material. Each conductor 3 is shaped as a U-shape. The stator core 1 is formed by laminating thin silicon steel sheets. A plurality of slots 4 are formed on the stator core 1 at even intervals. Each slot 4 has an opening 4 a at an inside of the stator core 1 and openings at both of axial sides. The stator core 1 is formed to accommodate a three-phase stator coil. The insulating member 2 may be made of, for instance, an insulating paper or a nonwoven fabric sheet.

As shown in FIG. 2, the U-shaped conductor 3 is a copper wire having a rectangular cross section corresponding to the slot 4 . The conductor 3 has accommodated portions 3 a to be accommodated into the slots 4 , a turn portion 3 b connecting the accommodated portions 3 a and connecting ends 3 c to be connected to the other conductor. The two accommodated portions 3 a are respectively inserted into the slots 4 spaced apart a predetermined pitch. After that, the two connecting ends 3 c of the U-shaped conductor 3 are respectively twisted in a predetermined direction for a predetermined pitch. After that, one of the connecting ends 3 c is connected to another one of the connecting ends 3 c . Then, the stator coil is produced. In this construction, one of the accommodated portions 3 a and the turn portion 3 b are connected via a bent portion 3 d.

Next, the inserting process and the expanding process of the insulating member 2 will be described with reference to FIGS. 3 through 7.

At first, longitudinal side edges of the sheet-shaped insulating member 2 are overlapped with each other by rounding the sheet-shaped insulating member 2 into cylindrical shape. Then, an overlapping portion 2 a is formed. The cylindrical insulating member 2 is inserted into the slot 4 from one axial end of the slot 4 so that the overlapping portion 2 a is positioned to oppose an inner surface of the slot 4 . In this embodiment, the overlapping portion 2 a is positioned in a radial outside. Each of the insulating members 2 provides an inner cavity for receiving and accommodating a conductor. Therefore, as shown in FIG. 3, the cylindrical-shaped insulating members 2 are disposed in the slots 4 to form a line.

Next, a former 5 heated to a predetermined temperature is pressed on ends of the insulating members 2 protruding from the slots 4 . The former 5 has a plurality of former dies 5 a integrally connected in a raw. Each of the former dies 5 a has a conical shape. In this embodiment, each of the former dies 5 a is shaped as a quadrangular pyramid. A tip 5 b of the die 5 a has a shape corresponding to a shape of the slot 4 to be able to be inserted into the slot. The former dies 5 a are located so that the former dies 5 a are inserted into alternate slots 4 simultaneously. The former dies 5 a may be arranged to insert every third slots or the like.

As shown in FIG. 4, the former 5 in which the former dies 5 a are heated to the predetermined temperature is moved by a driving device which is not shown so that the former dies 5 a are contacted with the ends of the insulating members 2 . As shown in FIG. 5, each of the insulating members 2 protruding from the slots 4 is compressed between the former die 5 a and an edge formed along an axial opening of the slot 4 . Each of the ends of the insulating members 2 is expanded as a funnel shape. Therefore, expanded ends 2 b are formed.

In the above-described process, the insulating member 2 is pressed on the edge 4 b formed between the axial end surface of the stator core 1 and the inner surface of the slot 4 . Therefore, a deformation mark 2 c , being thinner than the other portion, is formed on a portion where the insulating member 2 is compressed between the former die 5 a and the edge 4 b . The driving device moves the former 5 upwardly after the ends of the insulating members 2 are expanded as shown in FIG. 6 . The former 5 is moved for a slot in the circumferential direction of the stator core so that the former 5 is positioned above the insulating members 2 in which the ends are still not processed. After that, the former 5 is moved downwardly again, and is pressed on the insulating members 2 to process them as shown in FIG. 7 . Therefore, the ends of the insulating members 2 are processed at an above-described expanding process. As a result, the stator core 1 equipped with the insulating members 2 having the expanded ends is obtained as shown in FIG. 1 .

Next, a pushing-up process of the insulating member 2 and an inserting process of the conductors into the slots 4 will be described with reference to FIGS. 8 through 12.

At first, the insulating members 2 are moved for a predetermined distance by being pushed from the other ends of the insulating members 2 , that is, from the ends which are not processed by the heating and forming process as shown in FIGS. 8 and 9. The pushing-up process of the insulating members 2 is carried out by using a support plate 6 and a driving motor which is not shown. The process includes a step for bringing the support plate 6 to contact with the other ends of the insulating members 2 , and a step for pushing the support plate 6 by the driving motor to push all of the insulating members up simultaneously.

A plurality of U-shaped conductors 3 are inserted into bores defined by the insulating members 2 in the slots 4 . The conductors 3 are inserted from the expanded ends of the insulating members 2 after the pushing-up process of the insulating member 2 is completed as shown in FIG. 10 . At this time, the two accommodated portions 3 a of the U-shaped conductor 3 are accommodated into the slots 4 spaced apart a predetermined magnetic pole pitch respectively. The support plate 6 supports the other ends of the insulating members 2 even when the conductors 3 are inserted into the slots 4 . The process of inserting the conductors 3 into the slots 4 is progressed until the ends of the conductors 3 contact with the support plate 6 .

After the ends of the conductors 3 contact with the support plate 6 , the conductors 3 are moreover inserted with releasing a support by the support plate 6 . In this embodiment, the support is released by moving the support plate 6 back synchronously with an insertion of the conductor. The conductors 3 are inserted until the bent portions 3 d of the conductors 3 are rested on the edges 4 b of the slots 4 .

An appearance shown in FIG. 12 is obtained after the inserting process of the conductors 3 is completed. The deformation marks 2 c are placed on an out of the slots 4 when the insertion of the conductor 3 is completed.

The connecting ends 3 c of one conductor 3 are bent in an opposite circumferential directions to respectively make an electric conduction with the other conductor 3 spaced apart the predetermined magnetic pole pitch. The two connecting ends 3 c of different conductors 3 are joined. As a result, the conductors 3 construct the stator coil.

As shown in FIG. 13, the portion of the insulating member 2 opposing to the edge 4 b of the slot 4 is thinned as the deformation mark 2 c , because it is compressed between the edge 4 b and the former 5 . This thinned deformation mark 2 c is moved to the out of the slot 4 at the pushing-up process of the insulating member 2 . In the inserting process of the conductor 3 , the conductor 3 is inserted until the bent portion 3 d contacts with the edge 4 b of the slot 4 . Therefore, the insulating member 2 is pressed on the edge 4 b of the slot 4 by the bent portion 3 d of the conductor 3 .

However, the deformation mark 2 c has been pushed out to the out of the slot 4 . Therefore, a portion pressed on the edge 4 b by the conductor 3 is different from the portion of the thinned deformation mark 2 c . As a result, an insulation failure between the conductor 3 and the stator core 1 at the portion of the deformation mark 2 c is prevented.

In this embodiment, the support plate 6 supports the insulating members 2 at the ends not expanded. Therefore, it is prevented that the deformation mark 2 c is pushed back to the edge 4 b of the slot 4 again. This is effective to maintain the insulation.

In this embodiment, the forming dies 5 a each shaped into the quadrangular pyramid expand the ends of the insulating members 2 . Accordingly, the ends of the insulating members 2 can be easily expanded only by pressing the heated former die 5 a . Further, it is possible to improve easiness to insert the conductors 3 into the slots 4 by expanding the ends of the insulating members 2 .

In this embodiment, the former 5 has the plurality of former dies 5 a which are integrally connected in a line. The former 5 is constructed to be able to provide the heating and forming process to the plurality of insulating members 2 simultaneously. Therefore, it is possible to shorten a man-hour for the manufacturing process.

In this embodiment, the former 5 can be inserted into the slots 4 alternately. Therefore, the expanding process is easily carried out without a collision of adjacent former dies 5 a , even when the expanding process is carried out on the stator core 1 having a large number of slots provided at narrower intervals therebetween.

In this embodiment, the overlapping portion 2 a is formed by overlapping the ends of the sheet-shaped insulating member 2 formed into the cylindrical shape. The insulating member 2 covers and fills the inside opening 4 a of the slot 4 . The overlapping portion 2 a is positioned to oppose to the radial outside wall in the slot 4 and is sandwiched between the conductor 3 and the inner surface of the slot 4 . Therefore, it is possible to maintain the insulation certainly even under a strong vibration of the vehicular AC generator.

In this embodiment, the expanding portion 2 b is formed as the funnel shape. Alternatively, a shape having steps, a shape having a flange, a shape having expanded pleats or the like can be used as an alternative to provide similar functions and effects described above.

Although the present invention has been described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the present invention as defined in the appended claims.