JP2022052557A - Manufacturing method of rotor for rotary electric machine - Google Patents

Abstract

To use hydroforming to ensure the required tightening allowance between a rotor shaft and a rotor core near an axial end position of the rotor core.SOLUTION: A rotor manufacturing method for a rotary electric machine includes a step of preparing a rotor core and a hollow rotor shaft, an arrangement step of arranging the rotor core and the rotor shaft in a manufacturing device to form a state in which the rotor shaft is located radially inside the rotor core in the manufacturing device, and an integration step of fastening the rotor shaft and rotor core by increasing the internal pressure of the hollow portion of the rotor shaft while supporting the rotor shaft and rotor core by the manufacturing device, and in the integration step, a non-fastening portion axially adjacent to the fastening portion with the rotor core in the rotor shaft is deformed radially outward together with the fastening portion.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to a method for manufacturing a rotor for a rotary electric machine.

A technique of forming a convex portion on an iron pipe member by hydroforming is known.

Japanese Unexamined Patent Publication No. 2009-184573

By the way, in order to secure the necessary tightening allowance between the rotor shaft and the rotor core, press fitting and shrink fitting are used, and a technique using hydroforming is not known. When the internal pressure of the hollow portion of the rotor shaft is increased by hydroforming, the diameter of the center side in the axial direction is more likely to be expanded than that of the end side (that is, the bulge is easily deformed). Therefore, the rotor shaft tends to have a smaller diameter expansion amount on the end side in the axial direction than on the center side in the axial direction. As described above, when hydroforming is used, it is difficult to secure the necessary tightening allowance between the rotor shaft and the rotor core in the vicinity of the axial end position of the rotor core.

It is an object of the present disclosure to utilize hydroforming to ensure the required tightening allowance between the rotor shaft and the rotor core near the axial end position of the rotor core.

On one side, it is a method of manufacturing a rotor for a rotary electric machine.
The process of preparing the rotor core and the hollow rotor shaft,
An arrangement step of arranging the rotor core and the rotor shaft in a manufacturing apparatus and forming a state in which the rotor shaft is positioned radially inside the rotor core in the manufacturing apparatus.
After the arrangement step, the manufacturing apparatus includes an integration step of fastening the rotor shaft and the rotor core by increasing the internal pressure of the hollow portion of the rotor shaft while supporting the rotor shaft and the rotor core. ,
The integration step provides a manufacturing method in which a non-fastening portion axially adjacent to a fastening portion of the rotor shaft with the rotor core is deformed radially outward together with the fastening portion.

On one side, according to the present disclosure, hydroforming can be utilized to ensure the required tightening allowance between the rotor shaft and the rotor core in the vicinity of the axial end position of the rotor core.

It is sectional drawing which shows schematic the sectional structure of the motor by one Example. It is a schematic flowchart which shows the flow of the manufacturing method of a rotor. FIG. 1 is a cross-sectional view (No. 1) schematically showing a product state during manufacturing in the process shown in FIG. FIG. 2 is a cross-sectional view (No. 2) schematically showing a product state during manufacturing in the process shown in FIG. FIG. 3 is a cross-sectional view (No. 3) schematically showing a product state during manufacturing in the process shown in FIG. FIG. 4 is a cross-sectional view (No. 4) schematically showing a product state during manufacturing in the process shown in FIG. FIG. 3 is another cross-sectional view schematically showing the process according to FIG. 3D. FIG. 5 is a cross-sectional view (No. 5) schematically showing a product state during manufacturing in the process shown in FIG. FIG. 6 is a cross-sectional view (No. 6) schematically showing a product state during manufacturing in the process shown in FIG. FIG. 7 is a cross-sectional view (No. 7) schematically showing a product state during manufacturing in the process shown in FIG. It is an enlarged view of the Q1 part of FIG. 3G. It is sectional drawing for demonstrating the bulge deformation of a rotor shaft caused by the increase of internal pressure by hydroforming. It is explanatory drawing of the starting point of the bulge deformation by this Example. It is explanatory drawing of the starting point of the bulge deformation by the comparative example.

Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. The dimensional ratios in the drawings are merely examples and are not limited to these, and the shapes and the like in the drawings may be partially exaggerated for convenience of explanation. For example, a slight gap (for example, a gap for a required clearance) may be formed even between members having no gap in the drawing, and a gap may be formed even between members having a gap in the drawing. It may not be.

FIG. 1 is a cross-sectional view schematically showing a cross-sectional structure of a motor 1 (an example of a rotary electric machine) according to an embodiment.

FIG. 1 shows the rotation axis I of the motor 1. In the following description, the axial direction refers to the direction in which the rotation axis (rotation center) I of the motor 1 extends, and the radial direction refers to the radial direction centered on the rotation axis I. Therefore, the radial outer side refers to the side away from the rotation axis I, and the radial inner side refers to the side toward the rotation axis I. Further, the circumferential direction corresponds to the rotation direction around the rotation axis I.

The motor 1 may be a vehicle driving motor used in, for example, a hybrid vehicle or an electric vehicle. However, the motor 1 may be used for any other purpose.

The motor 1 is an inner rotor type, and the stator 21 is provided so as to surround the radial outer side of the rotor 30. The outer side of the stator 21 is fixed to the motor housing 10. The stator 21 is made of, for example, an annular magnetic laminated steel plate, and a plurality of slots (not shown) around which the coil 22 is wound are formed in the inner peripheral portion of the stator 21.

The rotor 30 is arranged radially inside the stator 21. The rotor 30 includes a rotor core 32 and a rotor shaft 34. The rotor core 32 is fixed to the radial outer side of the rotor shaft 34 and rotates integrally with the rotor shaft 34. The rotor shaft 34 is rotatably supported by the motor housing 10 via bearings 14a and 14b. The rotor shaft 34 defines the rotation axis I of the motor 1. Further, in this embodiment, the rotor shaft 34 has a circular cross-sectional shape, but the cross-sectional shape is arbitrary.

The rotor shaft 34 is connected to a power transmission mechanism 60 that transmits power to the wheels. That is, a power transmission mechanism 60 for transmitting the rotational torque of the motor 1 to the axle (not shown) is connected to the rotor shaft 34. FIG. 1 shows a shaft member 61 forming a part of the power transmission mechanism 60. The power transmission mechanism 60 may include a reduction mechanism, a differential gear mechanism, a clutch, a transmission, and the like. In the example shown in FIG. 1, the shaft member 61 is spline-coupled to the radial outer side of the rotor shaft 34. In this case, the peripheral surface of the end portion of the rotor shaft 34 on the outer side in the radial direction has a power transmission portion 345 forming a spline coupling portion (a gear portion composed of a plurality of axial protrusions). The shaft member 61 may be splined inward in the radial direction of the rotor shaft 34.

The rotor core 32 is made of, for example, an annular magnetic laminated steel plate. A permanent magnet 321 may be embedded inside the rotor core 32. Alternatively, the permanent magnet 321 may be embedded in the outer peripheral surface of the rotor core 32. When the permanent magnets 321 are provided, the arrangement of the permanent magnets 321 and the like is arbitrary.

End plates 35A and 35B are attached to both sides of the rotor core 32 in the axial direction. The end plates 35A and 35B may have a support function for supporting the rotor core 32 and a function for adjusting the imbalance of the rotor 30 (a function for eliminating the imbalance by cutting or the like).

The rotor shaft 34 has a hollow portion 343 as shown in FIG. The hollow portion 343 extends over the entire axial length of the rotor shaft 34.

As shown in FIG. 1, the rotor shaft 34 has a fastening portion 349A of a section SC1 in which a rotor core 32 is provided, a portion of a section SC2 in which bearings 14a and 14b are provided, and a first ejection hole 341 and a first ejection hole 341, which will be described later, in the axial direction. The portion of the section SC3 in which the second ejection hole 342 is provided is included. The section SC2 extends at both ends in the axial direction, and the section SC3 extends between the section SC1 and the section SC2 in the axial direction.

In this embodiment, as an example, the rotor shaft 34 has a shape in which the outer peripheral surface thereof is recessed inward in the radial direction in the section SC2. The rotor shaft 34 includes a large diameter portion 34A and a small diameter portion 34B having a smaller outer diameter than the large diameter portion 34A. As shown in FIG. 1, the small diameter portion 34B is formed on both sides of the large diameter portion 34A in the axial direction. The bearings 14a and 14b are provided on the small diameter portion 34B. The step in the radial direction between the large diameter portion 34A and the small diameter portion 34B may be formed substantially at a right angle to the rotation axis I, or may be formed in a tapered shape. In this embodiment, as an example, the radial step between the large diameter portion 34A and the small diameter portion 34B is formed at one end side (on the right side of the figure) at a substantially right angle to the rotation axis I, and is formed at a substantially right angle to the other end side. (On the right side of the figure), it is formed in a tapered shape.

Further, the rotor shaft 34 has bearing support surfaces 34a and 34b in the axial direction. The axial bearing support surfaces 34a and 34b support the bearings 14a and 14b by axially contacting the axial end surfaces of the inner races of the bearings 14a and 14b. The bearing support surfaces 34a and 34b in the axial direction are formed by denting the outer peripheral surface inward in the radial direction in the small diameter portion 34B of the rotor shaft 34. The bearing support surfaces 34a and 34b in the axial direction may be formed over the entire circumference of the rotor shaft 34 in the circumferential direction.

The rotor shaft 34 has a thick portion 347 in the form of a convex portion that is convex inward in the radial direction along the circumferential direction. The thick portion 347 is formed at a substantially center position in the axial direction of the rotor shaft 34 (a substantially center position in the axial direction in the section SC1). However, in the modified example, the thick portion 347 may or may not be slightly offset in the axial direction with respect to the axial center position of the rotor shaft 34. The thick portion 347 may be formed by, for example, casting, flow forming, friction welding, or the like. The method of forming the thick portion 347 by flow forming will be described later. In the case of friction welding, the rotor shaft 34 may be formed of two pieces that are axially divided at the center position. When the rotor shaft 34 includes the thick portion 347, the rigidity of the central portion of the section SC1 is higher than the rigidity of the end portion.

The rotor shaft 34 has a first ejection hole 341. The first ejection hole 341 penetrates outward from the hollow portion 343 in the radial direction. That is, the first ejection hole 341 has an opening 341a that opens in the hollow portion 343 and an opening 341b that faces the coil end 22A of the coil 22, and extends between the opening 341a and the opening 341b. The opening 341b of the first ejection hole 341 is arranged at a position displaced in the axial direction with respect to the rotor core 32 in a manner facing the coil end 22A of the coil 22. A plurality of first ejection holes 341 may be formed in the circumferential direction.

The rotor shaft 34 further has a second ejection hole 342 at a position in the axial direction different from that of the first ejection hole 341. The second ejection hole 342 penetrates outward from the hollow portion 343 in the radial direction. That is, the second ejection hole 342 has an opening 342a that opens in the hollow portion 343 and an opening 342b that faces the coil end 22B of the coil 22, and extends between the opening 342a and the opening 342b. The opening 342b of the second ejection hole 342 is arranged at a position displaced in the axial direction with respect to the rotor core 32 in a manner facing the coil end 22B of the coil 22. A plurality of second ejection holes 342 may be formed in the circumferential direction.

The inside of the rotor shaft 34 is connected to the oil supply source 90. The oil source 90 may include a pump 94. In this case, the type and driving mode of the pump 94 are arbitrary. For example, the pump 94 may be a gear pump that operates by the rotational torque of the motor 1. Oil is supplied into the rotor shaft 34 from one end (the right end in the figure) side of the rotor shaft 34. The pump 94 may be a housing (not shown) adjacent to the motor housing 10 and may be arranged in the housing accommodating the power transmission mechanism 60.

In FIG. 1, as an example, the oil supply source 90 includes a pipeline member 92 and a pump 94 connected to one end (the right end of the figure) side of the pipeline member 92.

The pipeline member 92 is formed hollow, and the inside defines the oil passage 801. That is, the pipeline member 92 has a hollow portion 92A that functions as an oil passage 801. The hollow portion 92A extends over the entire length of the pipeline member 92 in the axial direction. However, the hollow portion 92A does not open at one end side (the end portion on the left side of the figure and opposite to the pump 94 side). That is, one end (the left end in the figure) of the pipeline member 92 is closed.

The pipeline member 92 extends in the rotor shaft 34 so as to have a radial gap with respect to the inner peripheral surface 340 of the rotor shaft 34. Specifically, the pipeline member 92 has an outer diameter r4. The outer diameter r4 is significantly smaller than the inner diameters r1 and r3 of the inner peripheral surface 340 of the rotor shaft 34 in the sections SC1 and SC3 (note that in FIG. 1, the inner diameters r1 and r3 in the sections SC1 and SC3 are the same. be). The outer diameter r4 is substantially equal to, for example, the inner diameter r2 of the inner peripheral surface 340 of the rotor shaft 34 in the section SC2.

The pipeline member 92 includes a discharge hole 93 that penetrates from the inside to the outside in the radial direction. Discharge holes 93 are provided at an axial position corresponding to a substantially central position in the axial direction of the rotor core 32 and on both sides thereof. The position and number of the discharge holes 93 in the axial direction are arbitrary.

Next, the flow of oil from the oil supply source 90 will be outlined with reference to the arrows R1 to R6 shown in FIG. In FIG. 1, the flow of oil is schematically shown by arrows R1 to R6.

The oil supplied from the oil supply source 90 flows axially through the hollow portion 92A of the pipeline member 92 (see arrow R1), and is discharged radially outward from the discharge hole 93 (see arrow R2). The oil discharged radially outward from the discharge hole 93 hits the inner peripheral surface 340 of the rotor shaft 34, travels along the inner peripheral surface 340 of the rotor shaft 34, and shafts to the first ejection hole 341 and the second ejection hole 342. It flows in the direction (see arrows R3 and R4). In this case, the oil flowing outward in the axial direction along the inner peripheral surface 340 of the rotor shaft 34 can take heat from the radial inside of the rotor core 32 in the section SC1 and can efficiently cool the rotor core 32. ..

Here, in this embodiment, since the thick portion 347 is provided, the oil discharged radially outward from the discharge hole 93 is substantially evenly distributed to each of the first ejection hole 341 and the second ejection hole 342. Will be distributed. As a result, it is possible to equalize the oil distributed and guided to the coil ends 22A and 22B. As a result, the rotor core 32 can be uniformly cooled from the inside in the radial direction along the axial direction, and the coil ends 22A and 22B can be similarly cooled via the first ejection hole 341 and the second ejection hole 342, respectively. However, in the modified example, the oil flowing to each of the first ejection hole 341 and the second ejection hole 342 is provided by providing a deviation between the axial position of the discharge hole 93 and the axial position of the thick portion 347. It is also possible to positively set the difference (ie, the difference with respect to the amount of distribution) between the flow rates of.

Further, in the present embodiment, since the thick portion 347 is provided, the oil discharged from the discharge hole 93 to the outside in the radial direction travels along the inner peripheral surface 340 of the rotor shaft 34 while having a certain thickness. Can be done. That is, the thick portion 347 functions as a weir portion, and oil accumulation on the inner peripheral surface 340 of the rotor shaft 34 is promoted.

The oil that has flowed outward in the axial direction through the inner peripheral surface 340 of the rotor shaft 34 is discharged outward in the radial direction through the first ejection hole 341 due to the action of centrifugal force during rotation of the motor 1. See arrow R5). The opening 341b of the first ejection hole 341 faces the coil end 22A in the radial direction as described above. Therefore, the oil discharged to the outside in the radial direction through the first ejection hole 341 hits the coil end 22A and can efficiently cool the coil end 22A.

Further, the oil flowing outward in the axial direction through the inner peripheral surface 340 of the rotor shaft 34 is discharged outward in the radial direction through the second ejection hole 342 due to the action of centrifugal force during rotation of the motor 1. (See arrow R6). The opening 342b of the second ejection hole 342 faces the coil end 22B in the radial direction as described above. Therefore, the oil discharged to the outside in the radial direction through the second ejection hole 342 hits the coil end 22B and can efficiently cool the coil end 22B.

As described above, in this embodiment, it is possible to promote the flow of oil along the inner peripheral surface 340 of the rotor shaft 34. As a result, the rotor core 32 can be efficiently cooled from the inside in the radial direction by the oil transmitted through the inner peripheral surface 340 of the rotor shaft 34, and the coil ends 22A and 22B are efficiently cooled through the first ejection hole 341 and the second ejection hole 342. Can be cooled.

In particular, in this embodiment, the inner peripheral surface 340 of the rotor shaft 34 has an inner diameter r1 in the section SC1 that is significantly larger than the inner diameter r2 in the section SC2. That is, the inner peripheral surface 340 of the rotor shaft 34 is expanded in diameter in the section SC1 in which the rotor core 32 is provided. As a result, the weight of the rotor shaft 34 can be reduced, and the radial distance between the inner peripheral surface 340 of the rotor shaft 34 and the permanent magnet 321 can be shortened (compared to the case where the inner diameter r1 ≈ inner diameter r2). ), Magnet cooling performance can be effectively improved.

Although the motor 1 having a specific structure is shown in FIG. 1, the structure of the motor 1 is arbitrary as long as the rotor core 32 is fastened to the rotor shaft 34 having the hollow portion 343. Therefore, for example, the pipeline member 92 and the like may be omitted. For example, when the pipeline member 92 is omitted, oil may be supplied from the hollow portion of the shaft member 61. In this case, the shaft member 61 may be fitted inside the rotor shaft 34 in the radial direction.

Further, although a specific cooling method is disclosed in FIG. 1, the cooling method of the motor 1 is arbitrary. Therefore, for example, an oil passage may be formed in the rotor core 32, or oil may be dropped from the outside in the radial direction toward the coil ends 22A and 22B by the oil passage in the motor housing 10. Further, in FIG. 1, the pipeline member 92 of the oil supply source 90 is inserted into the rotor shaft 34 from the side connected to the power transmission mechanism 60 in the axial direction in the motor 1, but in the axial direction in the motor 1. It may be inserted into the rotor shaft 34 from the side opposite to the side connected to the power transmission mechanism 60. Further, in addition to oil cooling, a water cooling method using cooling water may be used.

Next, an example of a method for manufacturing the rotor 30 in the motor 1 of the above-described embodiment will be described with reference to FIGS. 2 and 3A to 3H. In FIG. 3B, the Z1 side and the Z2 side along the Z direction are defined together with the Z direction parallel to the rotation axis I. In the following, for the sake of explanation, as an example, it is assumed that the Z direction corresponds to the vertical direction and the Z2 side is the lower side in the manufacturing process. Further, FIG. 3B and the like show the reference axis I ₀ in the manufacturing apparatus 200. The reference axis I ₀ constitutes a central axis at the time of centering the work and corresponds to the above-mentioned rotation axis I.

FIG. 2 is a schematic flowchart showing the flow of a manufacturing method of the rotor 30, and FIGS. 3A to 3H are cross-sectional views schematically showing the states of the rotor shaft 34 and the rotor core 32 in some steps shown in FIG. be. 3B to 3D, 3F, 3G, and 3H are cross-sectional views when cut in a plane including the reference axis I ₀ , and FIG. 3E is cut in a plane perpendicular to the reference axis I ₀ . It is a cross-sectional view at the time of.

First, the method for manufacturing the rotor 30 includes a preparatory step (step S500) for preparing each of the rotor shaft 34 and the rotor core 32 (in a state where they are not connected to each other) as a work. The thick portion 347 of the rotor shaft 34 may be formed by flow forming processing, spinning processing, or the like.

As shown in FIG. 3A, the inner diameter r1'of the portion corresponding to the section SC1 of the rotor shaft 34 at this stage may be slightly smaller than the inner diameter r1 (see FIG. 1) in the product state. However, in the modified example, the inner diameter r1'may be substantially the same as the inner diameter r1 (see FIG. 1) in the product state. In this case, the fastening step described later is a step for increasing the fastening force between the rotor shaft 34 and the rotor core 32.

Further, similarly to the rotor shaft 34, the outer diameter of the rotor core 32 at this stage may be slightly smaller than the outer diameter in the product state. This is because the rotor core 32 is slightly deformed radially outward as the diameter of the rotor shaft 34 increases in the fastening process described later.

Then, as shown in FIG. 3B, the method for manufacturing the rotor 30 includes a step (step S501) (an example of an arrangement step) of setting the rotor shaft 34 and the rotor core 32 with respect to the manufacturing apparatus 200. The manufacturing apparatus 200 is a form of manufacturing equipment, and includes various jigs and molds described below. In the example shown in FIG. 3B, the manufacturing apparatus 200 includes a fixed mold 201 on the Z2 side, and a portion on the Z2 side of the rotor shaft 34 (ends of the small diameter portion 34B and the large diameter portion 34A) in the hollow portion 2011 of the fixed mold 201. ) Is inserted. At this time, the rotor shaft 34 is supported by the fixed mold 201 by the bearing support surface 34b abutting on the stepped surface 201b of the fixed mold 201 in the axial direction. The stepped surface 201b of the fixed type 201 is perpendicular to the reference axis I ₀ and may be formed around the reference axis I ₀ over the entire circumference. In the modified example, the Z1 side portion of the rotor shaft 34 (the end portion of the small diameter portion 34B and the large diameter portion 34A on the side where the bearing 14a is provided) may be inserted into the hollow portion 2011 of the fixed mold 201.

The fixed type 201 has a support surface 2012 that supports the end surface 32b on the Z2 side of the rotor core 32. The support surface 2012 may support the entire end surface 32b on the Z2 side of the rotor core 32, or may support a part of the end surface 32b.

In this way, when the rotor shaft 34 and the rotor core 32 are set with respect to the fixed mold 201 of the manufacturing apparatus 200, the fixed mold 201 of the manufacturing apparatus 200 simultaneously supports the rotor shaft 34 and the rotor core 32 from the Z2 side. Then, the movement (displacement) of the rotor shaft 34 and the rotor core 32 toward the Z2 side is restrained.

When the rotor shaft 34 and the rotor core 32 are set with respect to the fixed type 201 of the manufacturing apparatus 200, the outer diameter r11 of the rotor shaft 34 is the inner diameter of the rotor core 32 (as shown schematically in FIG. 3B). The diameter of the hole in the axis) is slightly smaller than r12. As a result, the rotor shaft 34 can be easily set inside the rotor core 32 in the radial direction. However, as described above, in the modified example, the outer diameter r11 of the rotor shaft 34 may be substantially the same as the inner diameter (diameter of the hole in the axial center) r12 of the rotor core 32.

Further, the rotor shaft 34 and the rotor core 32 do not necessarily have to be set to the fixed mold 201 of the manufacturing apparatus 200 at the same time, and may be set to the fixed mold 201 of the manufacturing apparatus 200 in order.

Then, as shown in FIG. 3C, the method for manufacturing the rotor 30 includes a step (step S502) of aligning the central axis I ₁ (see FIG. 3A) of the rotor shaft 34 with the reference axis I ₀ . That is, the method for manufacturing the rotor 30 includes a step of centering the rotor shaft 34 with respect to the reference axis I ₀ defined in the manufacturing apparatus 200.

In this embodiment, as shown in FIG. 3C, the centering of the rotor shaft 34 is realized by the seal molds 202 and 203 of the manufacturing apparatus 200 as an example. The seal types 202 and 203 have a configuration on the equipment side that is accurately centered with respect to the reference axis I ₀ .

Specifically, the seal type 202 on the Z2 side moves from the Z2 side to the Z1 side with respect to the rotor shaft 34, and is set with respect to the rotor shaft 34. The seal type 202 has a portion 2021 having an outer diameter corresponding to the inner diameter of the small diameter portion 34B on the Z2 side of the rotor shaft 34 (see the inner diameter r2 in FIG. 1). The central axis of site 2021 exactly coincides with reference axis I ₀ . The outer diameter of the cross section of the portion 2021 when cut in a plane perpendicular to the reference axis I ₀ is circular, and the outer diameter of the circular shape is slightly smaller than the inner diameter of the small diameter portion 34B on the Z2 side of the rotor shaft 34. It can be small. As a result, the rotor shaft 34 is centered from the inside in the radial direction by the portion 2021 of the seal type 202 that is accurately centered with respect to the reference axis _I0 .

As shown in FIG. 3C, the seal type 202 may have a stepped surface 2022 on the Z2 side of the portion 2021 in the radial direction. When the seal type 202 is set with respect to the rotor shaft 34, the stepped surface 2022 of the seal type 202 may face or abut on the end surface 348b on the Z2 side of the rotor shaft 34 in the axial direction.

Further, the seal type 203 on the Z1 side moves from the Z1 side to the Z2 side with respect to the rotor shaft 34, and is set with respect to the rotor shaft 34. The seal type 203 has a portion 2031 having an outer diameter corresponding to the inner diameter of the small diameter portion 34B on the Z1 side of the rotor shaft 34 (see the inner diameter r2 in FIG. 1). The central axis of site 2031 exactly coincides with reference axis I ₀ . The outer diameter of the cross section of the portion 2031 when cut in a plane perpendicular to the reference axis _I0 is circular, and the outer diameter of the circular shape is slightly smaller than the inner diameter of the small diameter portion 34B on the Z1 side of the rotor shaft 34. It can be small. As a result, the rotor shaft 34 is centered from the inside in the radial direction by the portion 2031 of the seal type 203 that is accurately centered with respect to the reference axis _I0 .

As shown in FIG. 3C, the seal type 203 may have a stepped surface 2032 in the radial direction on the Z1 side of the portion 2031. When the seal mold 203 is set with respect to the rotor shaft 34, the stepped surface 2032 of the seal mold 203 may face or abut on the end surface 348a on the Z1 side of the rotor shaft 34 in the axial direction. In this embodiment, as a preferred example, when the seal type 203 is set with respect to the rotor shaft 34, the stepped surface 2032 of the seal type 203 is axially separated from the end surface 348a on the Z1 side of the rotor shaft 34. And face each other.

In this way, the rotor shaft 34 is centered from the inside in the radial direction by the seal molds 202 and 203 accurately centered with respect to the reference shaft _I0 . In this case, if the central axis I ₁ of the rotor shaft 34 is deviated from the reference axis I ₀ , the rotor shaft 34 has the seal types 202 and 203 so that the central axis I ₁ coincides with the reference axis I ₀ . , Position and posture are corrected. As a result, the rotor shaft 34 can be accurately centered from the inside in the radial direction by the seal molds 202 and 203 even when the rotor core 32 is arranged on the outside in the radial direction.

The seal types 202 and 203 may be set with respect to the rotor shaft 34 at the same time, or may be set with a time lag. For example, the seal type 202 may be set on the rotor shaft 34, and then the seal type 203 may be set on the rotor shaft 34. Further, the seal type 202 may be a non-movable type like the fixed type 201. In this case, the seal type 202 may be integrated with the fixed type 201.

Then, as shown in FIG. 3D, the method for manufacturing the rotor 30 includes a step (step S503) of aligning the central axis I ₂ (see FIG. 3A) of the rotor core 32 with the reference axis I ₀ . That is, the method for manufacturing the rotor 30 includes a step of centering the rotor core 32 with respect to the reference axis I ₀ defined in the manufacturing apparatus 200.

In this embodiment, as shown in FIG. 3D, the centering of the rotor core 32 is realized by the centering device 204 of the manufacturing device 200 as an example. As shown in FIGS. 3D and 3E, the centering device 204 is movable in a plane perpendicular to the reference axis I ₀ , and is arranged so as to be able to advance and retreat with respect to the reference axis I ₀ . As shown in FIG. 3E, three or more centering devices 204 are preferably provided. Further, as shown in FIG. 3D, the centering device 204 preferably extends axially over the entire axial direction of the rotor core 32 so as to act over the entire axial direction of the rotor core 32.

In the example shown in FIGS. 3D and 3E, three centering devices 204 are provided around the reference axis I ₀ at a distance of 120 degrees. When the centering device 204 advances toward the reference axis I ₀ (see arrow R300), the tip portion 2041 on the radial inner side of the centering device 204 comes into contact with the outer peripheral surface of the rotor core 32. Each centering device 204 moves toward the reference axis I ₀ until the distance of the tip portion 2041 to the reference axis I ₀ becomes a predetermined radius r30. The predetermined radius r30 may correspond to the regular outer diameter of the rotor core 32 (outer diameter centered on the rotation axis I). As a result, the rotor core 32 can be centered with high accuracy with respect to the reference axis I ₀ .

In this way, the rotor core 32 is centered from the outside in the radial direction by the centering device 204 that advances to the predetermined radius r30 accurately defined toward the reference axis _I0 . In this case, if the central axis I ₂ of the rotor core 32 is deviated from the reference axis I ₀ , the rotor core 32 is positioned by the centering device 204 so that the central axis I ₂ coincides with the reference axis I ₀ . Posture is corrected. As a result, the rotor core 32 can be accurately centered from the radial outside by the centering device 204 even when the rotor shaft 34 is arranged radially inside.

In the examples shown in FIGS. 3D and 3E, the centering device 204 is formed so that the tip portion 2041 makes line contact (line contact in the axial direction) with the outer peripheral surface of the rotor core 32. It may be formed to do so. In this case, the tip 2041 may have a curved surface along the outer peripheral surface of the rotor core 32 when viewed in the direction along the reference axis _I0 .

Then, as shown in FIG. 3F, the method for manufacturing the rotor 30 includes a step (step S504) in which the rotor core 32 is firmly fixed to the manufacturing apparatus 200 in a state of being centered in step S503. In the example shown in FIG. 3F, the manufacturing apparatus 200 includes a movable type 205 on the Z1 side. The movable type 205 can be translated in parallel with the reference axis I ₀ . The movable type 205 moves along the Z direction toward the end face 32a on the Z1 side of the rotor core 32, and abuts on the end face 32a to fix the rotor core 32 to the manufacturing apparatus 200.

Further, in the present embodiment, the movable type 205 has an annular shape in which the inside in the radial direction is the hollow portion 2051, similar to the fixed type 201 described above. In the movable type 205, the Z1 side portion (the end portion of the small diameter portion 34B and the large diameter portion 34A) of the rotor shaft 34 is inserted into the hollow portion 2051 in a state of being in contact with the end surface 32a of the rotor core 32. At this time, the bearing support surface 34a of the rotor shaft 34 abuts in the axial direction on the stepped surface 205a of the movable type 205. In this case, the rotor shaft 34 is constrained to be displaced toward the Z1 side along the Z direction with respect to the movable mold 205 by the bearing support surface 34a and the stepped surface 205a of the movable mold 205. The stepped surface 205a of the movable type 205 is perpendicular to the reference axis I ₀ and may be formed around the reference axis I ₀ over the entire circumference.

In this way, when the rotor shaft 34 and the rotor core 32 are set with respect to the movable mold 205 of the manufacturing apparatus 200, the movable mold 205 of the manufacturing apparatus 200 simultaneously supports the rotor shaft 34 and the rotor core 32 from the Z1 side. Then, the movement (displacement) of the rotor shaft 34 and the rotor core 32 toward the Z1 side is restrained.

Further, in the state where the rotor core 32 is set with respect to the movable type 205 of the manufacturing apparatus 200, the rotor core 32 is sandwiched between the movable type 205 and the fixed type 201 in the axial direction, so that the pressing force in the axial direction causes the rotor core 32 to be sandwiched in the axial direction. Radial displacement is also constrained. Therefore, even if the centering device 204 is subsequently moved (retracted) away from the rotor core 32 (see arrow R401 in FIG. 3F), the centered state of the rotor core 32 is maintained.

Next, although not shown, the method for manufacturing the rotor 30 includes a step (step S505) of sealing the hollow portion 343 of the rotor shaft 34 with respect to the outside of the rotor shaft 34 by the seal molds 202 and 203. For example, the rotor shaft 34 can be sealed by the seal molds 202 and 203 by further moving the seal mold 203 on the Z1 side from the Z1 side to the Z2 side with respect to the rotor shaft 34. In this case, the rotor shaft 34 is firmly fixed to the manufacturing apparatus 200 in the state of being centered in step S502. In this way, the centering of the rotor shaft 34 is realized at a certain level in step S502, and may be realized at a perfect level in this step S505.

Next, as shown in FIG. 3G, the method for manufacturing the rotor 30 includes a fastening step (step S506) (an example of an integration step) of fixing (fastening) the rotor core 32 to the rotor shaft 34 by hydroforming. For example, as schematically shown in FIG. 3G, a fluid is introduced into the hollow portion 343 in a state where the rotor shaft 34 is pressed by the seal molds 202 and 203, and the fluid is pressurized to the inside of the rotor shaft 34. A force (internal pressure) perpendicular to the inner peripheral surface 340 is applied to the peripheral surface 340 (see arrows R31 and R32 in FIG. 3G). As a result, the diameter of the rotor shaft 34 is expanded, and a radial tightening allowance between the rotor shaft 34 and the rotor core 32 is secured (see FIG. 3H). That is, as the inner diameter r1'of the rotor shaft 34 is expanded to the inner diameter r1, the outer diameter r11 is increased by that amount, and the tightening allowance is secured. According to such hydroforming, it is possible to prevent inconveniences (for example, tilting of the rotor core 32 at the time of press fitting) that may occur in the fitting method of the rotor shaft 34 and the rotor core 32 such as press fitting.

Here, in this embodiment, as described above, the rotor core 32 is centered by the centering device 204 before the fastening step of step S506. Therefore, the rotor core 32 and the rotor shaft 34 can be fastened with the rotor core 32 centered. Further, in the present embodiment, in the fastening step of step S506, a state in which axial and radial displacements are constrained between the fixed mold 201 and the movable mold 205 is maintained. Therefore, it is possible to reduce the possibility that the centered state of the rotor core 32 is impaired during the fastening process.

Further, in the present embodiment, as described above, since the rotor shaft 34 is expanded in diameter with the rotor core 32 centered, the expanded rotor shaft 34 is also centered on the outside in the radial direction. It will be centered by the rotor core 32. As a result, the rotor core 32 and the rotor shaft 34 can be fastened in a state of being accurately centered with respect to the reference shaft _I0 .

Next, the method for manufacturing the rotor 30 includes a ejection hole forming step (step S508) for forming holes corresponding to the first ejection hole 341 and the second ejection hole 342 in the rotor shaft 34. The ejection hole forming step may be executed after the rotor shaft 34 is taken out from the manufacturing apparatus 200. When the ejection hole forming step (step S508) is completed, the final rotor shaft 34 is completed.

The method for manufacturing the rotor 30 then includes another finishing step (step S510). Other finishing steps may include a step of fixing the permanent magnet 321, a step of magnetizing, a step of adjusting the rotational balance by the end plates 35A and 35B, and the like.

In this way, according to the method for manufacturing the rotor 30 described with reference to FIGS. 2 and 3A to 3H, the rotor core 32 and the rotor shaft 34 are centered with respect to the reference shaft _I0 of the manufacturing apparatus 200. The rotor core 32 and the rotor shaft 34 can be integrated by hydroforming while forming and maintaining the state. As a result, the rotor 30 with reduced imbalance around the rotation axis I can be manufactured. Further, since the diameter of the rotor shaft 34 can be expanded by hydroforming in the centered state, the tightening allowance related to the fastening between the rotor core 32 and the rotor shaft 34 can be made uniform along the circumferential direction.

Here, the relationship between the movable type 205 and the rotor core 32 and the rotor shaft 34 will be described in detail with reference to FIGS. 4 and later. The relationship between the movable type 205 and the rotor core 32 and the rotor shaft 34 described below may be the same as the relationship between the fixed type 201 and the rotor core 32 and the rotor shaft 34.

FIG. 4 is an enlarged view of the Q1 portion of FIG. 3G. Unless otherwise specified, the relationship between the movable type 205 and the rotor core 32 and the rotor shaft 34 described below is the relationship before the execution of the fastening step (step S506).

When the movable type 205 is divided into three sections in the axial direction, as shown in FIG. 4, the movable type 205 includes a first part 205A, a second part 205B, and a third part 205C.

The first portion 205A overlaps a part of the large diameter portion 34A of the rotor shaft 34 when viewed in the radial direction. Of the large diameter portion 34A of the rotor shaft 34, the portion where the first portion 205A overlaps in the radial direction is axially adjacent to the fastening portion between the rotor core 32 and the rotor shaft 34 from the outside in the axial direction. do. In this embodiment, as an example, the above-mentioned first ejection hole 341 is formed in a portion of the large diameter portion 34A of the rotor shaft 34 where the first portion 205A overlaps in the radial direction.

In this embodiment, as shown in FIG. 4, the first portion 205A is radially separated from the rotor shaft 34. That is, the inner diameter of the first portion 205A is larger than the outer diameter of the large diameter portion 34A of the rotor shaft 34 (however, the outer diameter before hydroforming in the fastening process). In this embodiment, the first portion 205A is radially separated from the rotor shaft 34 over the entire length in the axial direction, but only the portion of the total length in the axial direction on the Z2 side in the axial direction is the rotor shaft. It may be separated from 34 in the radial direction. That is, in the first portion 205A, the end portion on the Z1 side in the axial direction may abut on the rotor shaft 34 in the radial direction.

In this way, the first portion 205A is axially separated from the rotor shaft 34 while abutting on the end surface 32a of the rotor core 32 in the axial direction. The technical significance of the radial gap 70 between the first portion 205A and the rotor shaft 34 formed by such a separation will be described later with reference to FIG.

In this embodiment, the first portion 205A of the movable type 205 abuts on the end surface 32a of the rotor core 32 in the axial direction and is separated from the rotor shaft 34 in the radial direction. Therefore, the first portion 205A fulfills the axial positioning function (axial displacement prevention function) of the rotor core 32.

The second portion 205B overlaps a part or all of the small diameter portion 34B of the rotor shaft 34 when viewed in the radial direction. Of the small diameter portion 34B of the rotor shaft 34 on the Z1 side, the portion where the second portion 205B overlaps in the radial direction is the end portion on the Z1 side of the rotor shaft 34. Of the small diameter portion 34B of the rotor shaft 34 on the Z1 side, the portion where the second portion 205B overlaps in the radial direction may be only the portion outside the bearing support surface 34a in the axial direction, or the bearing support. A portion inside the surface 34a in the axial direction may be included.

Unlike the first portion 205A, the second portion 205B may abut in the radial direction with respect to the rotor shaft 34. Alternatively, the second portion 205B may be closer to the rotor shaft 34 in the radial direction than the first portion 205A. For example, the second portion 205B may be radially separated from the rotor shaft 34 by the minimum clearance in consideration of tolerances and the like.

The third portion 205C is located between the first portion 205A and the second portion 205B and radially faces the transition section between the large diameter portion 34A and the small diameter portion 34B. As shown in FIG. 4, the third portion 205C is radially separated from the rotor shaft 34. For example, the third portion 205C may be radially separated from the rotor shaft 34 by the minimum clearance in consideration of tolerances and the like.

FIG. 5 is a cross-sectional view for explaining the bulge deformation of the rotor shaft 34'due to the increase in internal pressure due to hydroforming. FIG. 6 is an explanatory diagram of the effect (technical significance) relating to the radial gap 70 between the first portion 205A and the rotor shaft 34, and is an explanatory diagram of the starting point of the bulge deformation according to the present embodiment. FIG. 7 is an explanatory diagram of the starting point of the bulge deformation according to the comparative example. 5 to 7 schematically show a cross section on one side in the radial direction with respect to the reference axis I ₀ when cut in a plane including the reference axis I ₀ . Note that FIGS. 6 and 7 show lines L600 and 601 schematically showing the deformation mode of the bulge deformation, and the lines L600 and 601 exaggerate the amount of deformation (diameter expansion amount). , Does not represent the actual amount of deformation.

By the way, when the diameter of a hollow member such as the rotor shaft 34 is expanded by the hydroforming pressure (internal pressure), bulge deformation is likely to occur. Specifically, as schematically shown in FIG. 5, when the diameter of the rotor shaft 34'is expanded due to the hydroforming pressure (internal pressure), it is shown by the change from the state S400 to the state S401 in FIG. In addition, the method of deforming the rotor shaft 34'outward in the radial direction (diameter expansion amount) is not uniform along the axial direction. More specifically, barrel-shaped bulge deformation in which the inner diameter r40 in the central portion is larger than the inner diameter r41 in the end portion is likely to occur. When such barrel-shaped bulge deformation occurs, the tightening allowance tends to fluctuate depending on the position in the axial direction, and the tightening allowance at the axial end portion of the rotor core 32 tends to be insufficient. In addition, in FIG. 5, in the state S401, the warp is schematically expressed for the rotor shaft 34'which has a shape different from that of the rotor shaft 34, but the rotor shaft 34 can also have substantially the same deformation mode. In this embodiment, since the rotor shaft 34 has a thick portion 347, barrel-shaped bulge deformation can be reduced as compared with the above-mentioned rotor shaft 34', and a tightening margin at the axial end portion of the rotor core 32 is secured. It will be easier to do.

Here, the comparative example shown in FIG. 7 is different from the present embodiment in that it does not have the above-mentioned gap 70 (the radial gap 70 between the rotor shaft 34 and the movable type 205 and the fixed type 201). .. That is, in the comparative example, the movable type 205'contacts the outer peripheral surface of the rotor core 32 at the position P70 axially adjacent to the axial end portion of the rotor core 32. In this case, since the movable type 205'contacts the outer peripheral surface of the rotor core 32 at the position P70 axially adjacent to the axial end portion of the rotor core 32, the rotor core 32 is radially outer due to the movable type 205'. Hard to transform into. This also applies to the fixed type 201'side. That is, since the fixed mold 201 ′ comes into contact with the outer peripheral surface of the rotor core 32 at the position P71 axially adjacent to the axial end portion of the rotor core 32, the rotor core 32 is radially outward due to the fixed mold 201 ′. Hard to deform. As a result, the rotor shaft 34 tends to be bulge-deformed starting from the positions P70 and P71 at both ends in the axial direction of the rotor core 32 (see L601 in FIG. 7). Since the amount of deformation is relatively small near the starting point of bulge deformation, the tightening allowance tends to be insufficient. Therefore, in the comparative example, it is difficult to secure a tightening margin at the axial end portion of the rotor core 32.

On the other hand, in this embodiment, as shown in FIG. 6, the rotor shaft 34 has the above-mentioned gap 70 (the radial gap 70 between the rotor shaft 34 and the movable type 205 and the fixed type 201). Can be deformed radially outward by the amount of the gap 70. That is, unlike the comparative example, the movable type 205 and the fixed type 201 do not prevent the rotor shaft 34 from deforming outward in the radial direction (diameter expansion). In other words, the gap 70 is formed so that the movable mold 205 and the fixed mold 201 do not substantially hinder the radial outward deformation (diameter expansion) of the rotor shaft 34 in the fastening step (step S506). As a result, in this embodiment, the rotor shaft 34 is likely to be bulge-deformed starting from the positions P60 and P61 axially outside the starting point position of the bulge deformation in the comparative example (see L600 in FIG. 6). That is, the starting point positions P60 and P61 of the bulge deformation in the case of this embodiment are axially outside the positions P70 and P71 at both ends in the axial direction of the rotor core 32. Therefore, according to this embodiment, the tightening allowance between the rotor shaft 34 and the rotor core 32 can be increased in the vicinity of the axial end position of the rotor core 32 as compared with the comparative example shown in FIG.

In particular, in this embodiment, the above-mentioned gap 70 (diametrical gap 70 between the rotor shaft 34 and the movable type 205 and the fixed type 201) extends to the axial end portion of the large diameter portion 34A. That is, the first portion 205A is radially separated from the rotor shaft 34 over the entire axial direction. In this embodiment, since the gap 70 extends in the axial direction to both ends in the axial direction of the large diameter portion 34A, the rotor shaft 34 is likely to be bulge-deformed starting from the positions P60 and P61 at both ends of the large diameter portion 34A. See L600 in FIG. 6). As a result, the tightening allowance between the rotor shaft 34 and the rotor core 32 can be effectively increased in the vicinity of the axial end position of the rotor core 32.

As described above, the radial gap 70 between the first portion 205A of the movable type 205 and the rotor shaft 34 is the amount of expansion of the rotor shaft 34 in the fastening step (step S506), and is formed in the first portion 205A. It functions to increase the amount of diameter expansion of the portions of the rotor shafts 34 facing each other in the radial direction as compared with the comparative example. With this function, of the large diameter portion 34A of the rotor shaft 34, the non-fastening portion 349B adjacent to the fastening portion 349A from the outside in the axial direction is the fastening step by a maximum corresponding to the radial dimension of the gap 70. The diameter can be increased by (step S506). Therefore, by appropriately setting the radial dimension of the gap 70, as a result of the fastening process, the tightening allowance between the rotor shaft 34 and the rotor core 32 can be appropriately set in the vicinity of the axial end position of the rotor core 32. Can be secured.

In this embodiment, the dimension of the radial gap 70 between the first portion 205A and the rotor shaft 34 may be constant or slightly different along the axial direction. For example, the dimension of the radial gap 70 between the first portion 205A and the rotor shaft 34 may change in a manner that decreases toward the Z1 side along the axial direction. In this case, the dimension of the gap 70 becomes maximum at a position adjacent to the rotor core 32 in the axial direction. This makes it easier to secure a tightening allowance between the rotor shaft 34 and the rotor core 32 in the vicinity of the axial end position of the rotor core 32.

Further, in the present embodiment, the first portion 205A is preferably radially separated from the rotor shaft 34 over the entire circumference around the reference axis _I0 . In this case, it is the diameter expansion amount of the rotor shaft 34 in the fastening step (step S506), and the diameter expansion amount of the portion of the rotor shaft 34 that faces the first portion 205A in the radial direction is set to the entire circumference around the reference axis _I0 . Can be increased over.

Although each embodiment has been described in detail above, the present invention is not limited to a specific embodiment, and various modifications and changes can be made within the scope of the claims. It is also possible to combine all or a plurality of the components of the above-described embodiment. Further, among the effects of each embodiment, the effect related to the dependent term is an additional effect distinct from the superordinate concept (independent term).

For example, in the above-described embodiment, the gap 70 is formed on both axial sides of the rotor core 32 (that is, in each of the movable type 205 and the fixed type 201), but may be formed only on one side in the axial direction of the rotor core 32. good.

Further, in the above-described embodiment, the gap 70 is formed by the components (movable type 205 and fixed type 201) of the manufacturing apparatus 200, but is not limited thereto. For example, the fastening process may be realized with the end plates 35A and 35B set on both sides of the rotor core 32 in the axial direction. In this case, the inside of the end plates 35A and 35B may be radially separated from the rotor shaft 34 to form a part or all of the above-mentioned gap 70.

1 ... Motor (rotary machine), 32 ... Rotor core, 34 ... Rotor shaft, 34A ... Large diameter part, 34B ... Small diameter part, 349A ... Fastening part, 349B ... Non Fastening site, 200 ... Manufacturing equipment

Claims (4)

It is a method of manufacturing rotors for rotary electric machines.
The process of preparing the rotor core and the hollow rotor shaft,
An arrangement step of arranging the rotor core and the rotor shaft in a manufacturing apparatus and forming a state in which the rotor shaft is positioned radially inside the rotor core in the manufacturing apparatus.
After the arrangement step, the manufacturing apparatus includes an integration step of fastening the rotor shaft and the rotor core by increasing the internal pressure of the hollow portion of the rotor shaft while supporting the rotor shaft and the rotor core. ,
The integration step is a manufacturing method in which a non-fastening portion axially adjacent to a fastening portion with the rotor core in the rotor shaft is deformed radially outward together with the fastening portion. The manufacturing method according to claim 1, wherein in the integration step, the manufacturing apparatus is axially separated from the non-fastened portion while abutting on the rotor core in the axial direction. The rotor shaft has a large diameter portion having a relatively large outer diameter and a small diameter portion having a relatively small outer diameter.
The manufacturing method according to claim 2, wherein the non-fastening portion is provided in the large diameter portion. The manufacturing method according to claim 3, wherein the radial gap between the manufacturing apparatus and the rotor shaft formed in the integration step extends to the axial end portion of the large diameter portion.

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