Patent Application
20110302769
The disclosure of Japanese Patent Application No. 2010-136034 filed on Jun. 15, 2010 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The present invention relates to a method of manufacturing a stator in which a coil conductor is arranged in slots of a stator core.
To manufacture a stator for a rotary electric machine that is used in a hybrid vehicle, an electric vehicle, or the like, a coil conductor is formed of a rectangular wire whose cross-section is generally rectangular-shaped in order to increase the area of the slot of a stator core occupied by the coil conductor. In this case, the coil conductor formed of the rectangular wire cannot be inserted into the slots in the annular stator core. A plurality of segment cores is thus formed by dividing the stator core at a formation position of every other slot.
The plurality of segment cores is then assembled to the coil conductor that is formed into a shape to be arranged in the slots. Further, for example, an outer peripheral ring is shrink-fit to an outer periphery of the plurality of segment cores (the outer peripheral ring is heated and expanded to be fit to the segment cores).
For example, in a method of manufacturing a rotary electric machine described in Japanese Patent Application Publication No. JP-A-2009-106137, a tightening member is attached to an outer periphery of a segment stator core, and presses each segment stator core radially inward so as to displace each segment stator core in order to secure an inner diameter circularity of a stator.
In addition, for example, Japanese Patent Application Publication No. JP-A-2001-218429 describes that, in an electric motor, a stator is manufactured by assembling a stator core in which a yoke portion is divided into a plurality of parts in a circumferential direction, and installing a metal mold on teeth tip end portions of the stator core so as to radially apply stress to the stator core in a uniform state in a circumferential direction.
However, it has been found that, when the coil conductor formed of the rectangular wire is assembled in a plurality of slots in the stator core in a bridged and distributed winding manner, the circularity of the stator is reduced after the outer peripheral ring is attached to the plurality of segment cores by shrink fitting. This reduction in the circularity is due to the following. That is, a dimensional error may occur between the slots and the coil conductor due to, for example, a variation in dimensional accuracy that occurs when the rectangular wire is processed by bending. This results in considerable deformation of the coil conductor arranged in the slots. Therefore, when all the segment cores are assembled to the coil conductor, a force that causes the deformed coil conductor to regain its original shape presses the plurality of segment cores toward an outer peripheral side, resulting in a reduction in circularity of the stator.
It should be noted that, in Patent Documents 1 and 2, there are no devices described for suppressing a reduction in the circularity after the above shrink-fitting.
The present invention has been devised in consideration of the foregoing problem with related art, and it is an object of the present invention to provide a method of manufacturing a stator that is capable of effectively suppressing a reduction in the circularity of the stator after a heated outer peripheral ring is fit to an outer periphery of a plurality of segment cores.
A first aspect of the present invention provides a method of manufacturing a stator, the method being characterized by including: a stator formation process of forming a stator by assembling a plurality of segment cores, which is formed by dividing a stator core in a circumferential direction at a formation position of a slot of the stator core, to a coil conductor that is formed of a rectangular wire bent to include linear portions arranged in the slot and bridge portions that alternately connects the linear portions on one end and the other end of the coil conductor such that the linear portions can be arranged side by side on an imaginary circumference, and fitting a heated outer peripheral ring to an outer periphery of the plurality of segment cores; and a correction process of reheating the stator at a predetermined temperature in a state where a circularity of the stator is corrected by restraining the outer peripheral ring in the stator so as to improve the circularity of the stator.
The stator manufactured according to the first aspect of the present invention is formed by assembling the coil conductor formed of the rectangular wire to the plurality of slots in the stator core in a bridged and distributed winding manner.
In the method of manufacturing a stator according to the first aspect of the present invention, the stator is formed in the stator formation process in which the plurality of segment cores is assembled to the coil conductor formed by bending the rectangular wire, and the heated outer peripheral ring is fit to the outer periphery of the plurality of segment cores. Then, in the correction process, the stator is reheated at the predetermined temperature in the state where the circularity of the stator is corrected by restraining the outer peripheral ring in the stator.
This reheating makes it possible to reduce a force that causes the coil conductor deformed when arranged in the slots to regain its original shape. Consequently, it is possible to suppress the force that causes the deformed coil conductor to regain its original shape from serving as a residual stress that presses and expands the segment cores.
Therefore, according to the method of manufacturing a stator of the first aspect of the present invention, it is possible to effectively suppress a reduction in the circularity of the stator after the heated outer peripheral ring is fit to the outer periphery of the plurality of segment cores.
An embodiment of a method of manufacturing a stator according to the present invention above will be described.
In a correction process according to the present invention, a predetermined temperature at which the stator is reheated may be set to equal to or lower than a heat-resistant temperature of an insulation layer that covers a rectangular wire forming a coil conductor. This predetermined temperature at which the stator is reheated may be set such that, for example, the temperature of the coil conductor becomes 100° C. to 200° C.
Further, in the correction process, a correction jig arranged on an outer peripheral side of an outer peripheral ring may be used to partially press the outer peripheral ring in the circumferential direction. The correction jig may include a body portion arranged on the outer peripheral side of the outer peripheral ring, and an adjustment portion whose radial position is adjusted with respect to the body portion and that presses a corresponding segment core from the outer peripheral side. In this case, it is possible to easily correct the circularity of the stator by attaching the correction jig to the stator to which the outer peripheral ring is shrink-fit and adjusting the adjustment portion.
Further, the body portion may be formed of an annular ring member, and the ring member may be formed with screw holes at positions facing an outer peripheral side of the plurality of segment cores. The adjustment portion may be an adjustment bolt that is screwed into each of the screw holes, and a tip end of the adjustment bolt may press the outer periphery of the corresponding segment core so as to improve the circularity of the stator.
In this case, it is possible to easily adjust a force that presses each of the segment cores by tightening the adjustment bolt, whereby the circularity of the stator is further improved.
Further, the correction process may be performed in a varnish impregnation process of impregnating varnish in a gap between the coil conductor and the slots, and the predetermined temperature at which the stator is reheated may be a heating temperature to harden the varnish.
In this case, it possible to reheat the stator utilizing the heating temperature when impregnating the varnish, whereby the time required for the correction process can be reduced and the equipment can be simplified.
Further, in the correction process, a radius from a center of the stator to teeth inner peripheral surfaces of each of the plurality of segment cores may be measured using a measuring device, and the segment core with the measured radius larger than that of the other segment cores may be pressed toward an inner peripheral side so as to improve the circularity of the stator.
In this case, it is possible to directly press toward the inner peripheral side the segment cores that should be corrected to ensure the circularity, whereby the circularity of the stator can be further improved.
An embodiment of a method of manufacturing a stator according to the present invention will be hereinafter described with reference to the drawings.
In a method of manufacturing a stator 1 according to the present embodiment, the stator 1 for a rotary electric machine is manufactured by performing a stator formation process and a correction process to be described next.
In the stator formation process, as shown in
In the correction process, as shown in
The method of manufacturing the stator 1 according to the present embodiment will be hereinafter described in detail with reference to
The stator 1 of the present embodiment is used for a three-phase rotary electric machine, and the three-phase rotary electric machine is configured such that an inner rotor is rotatably arranged on an inner peripheral side of the stator 1.
As shown in
As shown in
As shown in
As shown in
As shown in
In the coil conductor 3 arranged in the stator core 2, most of the linear portions 31 are arranged in the respective slots 23, and the remaining linear portions 31 and the bridge portions 32 are arranged on an outer side of an axial end surface of the stator core 2. The remaining linear portions 31 and the bridge portions 32 together form coil end portions 35 of the stator 1.
In the stator formation process of the present embodiment, after forming a segment core assembly 11 by assembling all the segment cores 25 to all the coil conductors 3 of the three phases, a shrink fit device 4 is used to shrink-fit the outer peripheral ring 26 to the segment core assembly 11 as shown in
The core holding portion 43 includes an inner peripheral side holding portion 431 that holds an inner peripheral side of the segment core assembly 11 on an inner peripheral side and an outer peripheral side holding portion 432 that holds an outer peripheral side of the segment core assembly 11. The ring holding portion 41 of the present embodiment is fixed to a base 45. The moving unit 44 is configured to move the core holding portion 43, and includes a movement base 441 that fixes the inner peripheral side holding portion 431 and fixes the outer peripheral side holding portion 432 via a cushion 433, and posts 442 that guide the movement of the movement base 441. The movement base 441 is configured to move by a power source (not shown) or a manually operated drive source.
As shown in
In the correction process of the present embodiment, as shown in
As shown in
Further, the correction process is performed in a varnish impregnation process in which gaps between the coil conductor 3 and the slots 23 are impregnated with varnish.
In the varnish impregnation process, as shown in
In the present embodiment, after the stator formation process described above is performed, the correction process is performed at the same time as the varnish impregnation process. In other words, after the outer peripheral ring 26 is shrink-fit to the segment core assembly 11 as shown in
Next, as shown in
It should be noted that heating of the stator 1 in the varnish impregnation process can be performed by using various heating methods, such as induction heating, heating with hot air, and heating by energizing the coil conductor 3.
There is a dimensional error between the slots 23 and the coil conductor 3 due to a variation in dimensional accuracy when the rectangular wire 301 is processed by bending. Therefore, the coil conductor 3 arranged in the respective slots 23 deforms considerably. Due to this deformation, when all the segment cores 25 are assembled to the coil conductor 3, the plurality of segment cores 25 is pressed toward the outer peripheral side by the force that causes the deformed coil conductor 3 to regain its original shape. If the force that presses the segment cores 25 toward the outer peripheral side becomes uneven, the circularity of the stator 1 is reduced.
Meanwhile, in the method of manufacturing the stator 1 according to the present embodiment, in the varnish impregnation process (correction process), the stator 1 is reheated at the predetermined temperature in the state where the circularity of the stator 1 is corrected by the correction jig 5. This reheating reduces the force that causes the coil conductor 3 deformed when arranged in the slots 23 to regain its original shape. Consequently, it is possible to suppress the force that causes the deformed coil conductor 3 to regain its original shape from serving as a residual stress that presses and expands the segment cores 25.
Accordingly, in the method of manufacturing the stator 1 of the present embodiment, it is possible to effectively suppress a reduction in the circularity of the stator 1 after the heated outer peripheral ring 26 is fit to the outer periphery of the plurality of segment cores 25.
Note that, as a method of suppressing a reduction in the circularity of the stator 1, a method may be employed to increase the thickness of the outer peripheral ring 26, or reduce the ratio of the slot 23 of the stator core 2 occupied by the coil conductor 3. However, such method may lower the performance of the rotary electric machine formed with the stator 1, and are therefore not adequate. On the contrary, by correcting the circularity of the stator 1 in the correction process as described above, it is possible to prevent the performance of the rotary electric machine from deteriorating.
Further, in the correction process described above, as shown in
Further, besides the reheating performed in the varnish impregnation process described above, reheating of the stator 1 in the correction process described above may also be performed by heating with hot air the stator 1 corrected using the correction jig 5. This heating with hot air can be performed, as shown in
Alternatively, reheating of the stator 1 in the correction process described above may be performed by induction heating of the stator 1 using an induction heating coil 83 arranged on the inner peripheral side of the stator 1, as shown in
Moreover, although not shown in the drawings, when heating the stator 1 with hot air or by induction heating, the stator 1 may be heated by energizing the coil conductor 3.
For this confirmation test, a test was conducted to confirm the effect achieved by performing the above correction process on the stator 1.
More specifically, the radius of the inner peripheral surfaces 221 on the teeth portions 22 in the stator 1 was measured by a measuring device at each of the following stages: before each segment core 25 in the stator 1 was corrected by the correction jig 5 (i.e., before performing the correction process); after each segment core 25 in the stator 1 was corrected by the correction jig 5 (after correction by jig); after each segment core 25 in the stator 1 was corrected by the correction jig 5 and reheated at the predetermined temperature (after heating); and after each segment core 25 in the stator 1 was corrected by the correction jig 5 and reheated at the predetermined temperature, and the correction jig 5 was detached (after jig detachment).
In the drawings, a 66-mm radius of the inner peripheral surfaces 221 on the teeth portions 22 is a center O of the graph circle, and a 67.8-mm radius of the inner peripheral surfaces 221 on the teeth portions 22 is a contour G of the graph circle. Lines H that radially extend indicate the formation positions of the slots 23.
As shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-136034 | Jun 2010 | JP | national |
