Motor manufacturing method

Abstract

The present invention improves the inner-diameter precision of a stator core to be inserted into a frame. The disclosed motor manufacturing method comprises: an assembly step for assembling a plurality of split cores with respective teeth sections to form an annular stator core (31); an insertion step for inserting the stator core (31) into a frame (40) by shrink fitting or press fitting; and a push-out step for pushing and spreading out the stator core (31) by pressing the inner circumferential surfaces of the teeth sections with a cylindrical jig (50) after the insertion step.

Description

Motor manufacturing method

[0001] The present disclosure relates to a method for manufacturing a motor.

[0002] A conventional motor manufacturing method includes a step of assembling a plurality of split cores to form an annular stator core (see, for example, Patent Document 1). In the motor manufacturing method of Patent Document 1, after the annular stator core is formed, the stator core is expanded with a jig to improve the inner diameter accuracy of the stator core.

[0003] Japanese Patent Application Laid-Open No. 2002-199666

[0004] However, when a stator core is inserted into a frame, the force generated when inserting the stator core into the frame may impair the accuracy of the inner diameter of the stator core. The motor manufacturing method of Patent Document 1 cannot address such a situation. In light of this situation, one of the objects of the present disclosure is to improve the accuracy of the inner diameter of a stator core inserted into a frame.

[0005] One aspect of the present disclosure relates to a motor manufacturing method, the manufacturing method including: an assembly step of assembling a plurality of split cores, each having teeth, to form an annular stator core; an insertion step of inserting the stator core into a frame by shrink fitting or press fitting; and, after the insertion step, an expansion step of expanding the stator core by pressing inner circumferential surfaces of the teeth with a cylindrical jig.

[0006] According to the motor manufacturing method of the present disclosure, it is possible to improve the inner diameter accuracy of the stator core that is inserted into the frame.

[0007] 1 is a perspective view illustrating an assembly process and an insertion process according to an embodiment of the present disclosure, and is a schematic diagram of a state in which an assembled stator core is inserted into a frame, a perspective view of a split core used in a stator core according to an embodiment of the present disclosure, and a cross-sectional view illustrating a pushing-out process according to an embodiment of the present disclosure.

[0008] An embodiment of a motor manufacturing method according to the present disclosure will be described below using examples. However, the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be used as examples, but other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained. Among the steps in the motor manufacturing method according to the present disclosure, steps that are not essential to the motor manufacturing method according to the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the actual shapes and numbers of components.

[0009] The manufacturing method of the motor of this embodiment includes an assembly process, an insertion process, and a spreading process. Each process will be described below with reference to Figures 1A, 1B, and 2 as needed.

[0010] Fig. 1A is a perspective view for explaining an assembly process and an insertion process according to the present embodiment, and is a schematic diagram of a state in which an assembled stator core 31 is inserted into a frame 40. Fig. 1B is a perspective view of a split core 32 used in the stator core 31 according to the present embodiment. Fig. 2 is a cross-sectional view for explaining a pushing-out process according to an embodiment of the present disclosure.

[0011] (Assembly Process) In the assembly process, a plurality of split cores 32 (see FIG. 1B), each having a yoke portion 32a and teeth portions 32b, are assembled to form an annular stator core 31 (see FIG. 1A). Note that the plurality of split cores 32 are each fitted with an insulator 33 and insulating paper (not shown), and are then wound with a coil 34, and then assembled to form the stator core 31. In this embodiment, the split cores 32 are made of a plurality of laminated steel plates, but the present invention is not limited to this.

[0012] Each split core 32 may have one tooth portion 32b. Each split core 32 may be formed by laminating a plurality of generally T-shaped electromagnetic steel plates.

[0013] 1A, in the insertion process, the stator core 31 is inserted into the frame 40 by shrink fitting. In this embodiment, the frame 40 is made of an aluminum alloy, but is not limited to this. The hardness of the frame 40 made of an aluminum alloy is lower than the hardness of the stator core 31 made of an electromagnetic steel plate. Note that the stator core 31 may also be inserted into the frame 40 by press fitting.

[0014] The frame 40 may be made of aluminum or an iron-based metal other than an aluminum alloy. Shrink fitting is particularly suitable when the frame 40 is made of aluminum or an aluminum alloy, and press fitting is particularly suitable when the frame 40 is made of an iron-based metal.

[0015] (Expansion Process) As shown in Figure 2, in the expansion process, after the insertion process, the inner peripheral surface 32c of each tooth portion 32b is pressed with a cylindrical jig 50 to expand the stator core 31. At this time, the outer peripheral surface 31a of the expanded stator core 31 neatly conforms to (or is in close contact with) the inner peripheral surface 40a of the frame 40. This improves the inner diameter accuracy of the stator core 31. In other words, the expansion process ensures that the inner peripheral surfaces 32c of each tooth portion 32b are neatly aligned along the cylindrical surface. Because this expansion process is performed after the stator core 31 is inserted into the frame 40, there are no subsequent processes that could impair the inner diameter accuracy of the stator core 31, and high inner diameter accuracy is maintained in the finished motor.

[0016] It is preferable that the expansion process be performed within a predetermined time after the completion of the insertion process. In particular, it is preferable that the insertion process be performed by shrink fitting, and that the expansion process be performed within a predetermined time after the completion of the insertion process. Here, the predetermined time is, for example, the time from immediately after the stator core 31 is inserted into the frame 40 heated for shrink fitting until the frame 40 reaches approximately room temperature (or reaches thermal equilibrium with the surrounding environment). By performing the expansion process shortly after shrink fitting, i.e., when the temperature of the frame 40 is high and its inner diameter is large, the stator core 31 can be expanded with a relatively small force. For example, it is preferable to expand the stator core 31 when the frame 40 is not completely cooled and there is a gap between the outer circumferential surface 31 a of the stator core 31 and the inner circumferential surface 40 a of the frame 40.

[0017] The outer periphery of the jig 50 may be made of an elastic body 52. ​​In other words, the portion of the jig 50 that contacts the inner periphery 32c of the teeth 32b may be made of the elastic body 52. ​​With this configuration, even if the outer diameter accuracy of the jig 50 is somewhat low, pressure can be applied evenly to the inner periphery 32c of each tooth 32b. The elastic body 52 may be made of, for example, silicone rubber or fluororubber. The jig 50 may be made, for example, by fitting a rubber tubular member onto an expandable metallic cylindrical member. The outer periphery of the jig 50 may be made of metal.

[0018] The remaining portion (or the main body) of the jig 50 may be configured as a metal cylinder 51 having a plurality of slits (not shown) formed therein and capable of expanding in diameter. The outer peripheral surface 51a of the cylinder 51 is cylindrical, while the inner peripheral surface 51b of the cylinder 51 is tapered. For example, by pushing a predetermined member into the jig 50 from above in FIG. 2 , the jig 50 may expand in diameter, applying pressure to the inner peripheral surfaces 32c of the teeth 32b. To prevent damage to the frame 40, the pressure applied at this time is preferably within the elastic range of the frame 40 and sufficient to expand the stator core.

[0019] The hardness of the frame 40 may be lower than that of the stator core 31. Such a low-hardness frame 40 is often made of a material with excellent thermal conductivity, such as aluminum or an aluminum alloy. This improves the heat dissipation performance of the motor. However, if the frame 40 has low hardness, there is a risk that the stator core 31 may come into contact with the frame 40 during insertion, resulting in damage to the frame 40. In contrast, in the motor manufacturing method according to the present disclosure, the stator core 31 is not yet expanded during the insertion process. This makes it easy to maintain a gap between the inner circumferential surface 40a of the frame 40 and the outer circumferential surface 31a of the stator core 31, making such damage to the frame 40 less likely. The hardness may be, for example, Vickers hardness measured using a measurement method specified in JIS Z 2244.

[0020] As described above, according to the present disclosure, by performing the pushing-out process after the insertion process, it is possible to improve the inner diameter accuracy of the stator core 31 inserted into the frame 40. Furthermore, according to the present disclosure, by providing the stator core 31 with high inner diameter accuracy, it is possible to suppress the cogging torque of the motor.

[0021] <<Notes>> The above description of the embodiment discloses the following techniques.

[0022] (Technology 1) A method for manufacturing a motor, comprising: an assembly process for assembling a plurality of split cores, each having teeth, to form an annular stator core; an insertion process for inserting the stator core into a frame by shrink fitting or press fitting; and, after the insertion process, a pushing-out process for pushing the inner circumferential surfaces of the teeth with a cylindrical jig to push out the stator core.

[0023] (Technology 2) The motor manufacturing method according to Technology 1, wherein the inserting step is performed by shrink fitting, and the expanding step is performed within a predetermined time after the insertion step is completed.

[0024] (Technology 3) The motor manufacturing method according to Technology 1 or 2, wherein the outer periphery of the jig is made of an elastic body.

[0025] (Technology 4) The method of manufacturing a motor according to any one of Technologies 1 to 3, wherein the frame has a hardness lower than that of the stator core.

[0026] The motor manufacturing method of the present disclosure can suppress the cogging torque of the motor, and is thus industrially useful.

[0027] 31: Stator core 31a: Outer peripheral surface 32: Split core 32a: Yoke portion 32b: Teeth portion 32c: Inner peripheral surface 33: Insulator 34: Coil 40: Frame 40a: Inner peripheral surface 50: Jig 51: Cylindrical body 51a: Outer peripheral surface 51b: Inner peripheral surface 52: Elastic body

Claims

1. A method for manufacturing a motor, comprising: an assembly process for assembling a number of split cores, each having teeth, to form a ring-shaped stator core; an insertion process for inserting the stator core into a frame by shrink fitting or press fitting; and, after the insertion process, a pushing and expanding process for pushing and expanding the stator core by pressing the inner surfaces of the teeth with a cylindrical jig.

2. The method of manufacturing a motor according to claim 1, wherein the inserting step is performed by shrink fitting, and the expanding step is performed within a predetermined time after the completion of the inserting step.

3. The method of manufacturing a motor according to claim 1 or 2, wherein the outer periphery of the jig is made of an elastic material.

4. The method for manufacturing a motor according to claim 1 or 2, wherein the hardness of the frame is lower than the hardness of the stator core.

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