JP6759705B2 - How to manufacture the rotor - Google Patents

Description

The present invention relates to a rotor manufacturing how.

Conventionally, as a rotor of a motor, there is one provided with a rotating shaft, a rotor core externally fitted and fixed to the rotating shaft, and a plurality of permanent magnets provided on the outer surface side of the rotor core in the circumferential direction. As such a rotor, the permanent magnets have a curved shape in which the central portion in the circumferential direction on the outer surface thereof is farther from the center of the axial direction than both ends in the circumferential direction, and each permanent magnet has a curved shape. Some are covered and held by a tubular non-magnetic cover (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2015-231254

However, in the rotor described above, the inner surface of the non-magnetic cover is shown in a perfect circular shape in contact with only the central portion in the circumferential direction on the outer surface of the permanent magnet, and the configuration for firmly holding the permanent magnet is not disclosed. .. Therefore, a rotor capable of easily and firmly holding a permanent magnet and a method for manufacturing the same are desired.

The present invention was made to solve the above problems, and an object thereof is to provide a manufacturing how the rotor can be firmly held easily permanent magnets.

In a method for manufacturing a rotor that solves the above problems, a plurality of rotor cores are provided in the circumferential direction in contact with the rotor core and the outer surface of the rotor core, and when viewed from the axial direction, the central portion in the circumferential direction on the outer surface is larger than both ends in the circumferential direction. A method for manufacturing a rotor including a curved permanent magnet that is far from the center of the shaft and a tubular non-magnetic cover that covers the outer surface of each permanent magnet. The large diameter portion having a large inner diameter and the inner diameter A non-magnetic cover molding step of molding the non-magnetic cover in which small small-diameter portions are arranged side by side in the axial direction, and an inner surface of the large-diameter portion and a state in which the permanent magnet is brought into contact with the outer surface of the rotor core. The cover press-fitting step of press-fitting the non-magnetic cover molded in the non-magnetic cover molding step so that the inner surface of the small diameter portion is in contact with the outer surface of the permanent magnet is provided . The rotor core is formed by press-fitting from the large-diameter portion of the cover and having a high-hardness portion having a high hardness and a low-hardness portion having a low hardness arranged side by side in the axial direction. In the press-fitting step, the non-magnetic cover is press-fitted from the high hardness portion side .

According to this method, in the molding step, a non-magnetic cover in which a large diameter portion having a large inner diameter and a small diameter portion having a small inner diameter are arranged side by side in the axial direction is molded. Then, in the cover press-fitting step, the non-magnetic cover is molded so that the inner surface of the large-diameter portion and the inner surface of the small-diameter portion both come into contact with the outer surface of the permanent magnet while the permanent magnet is in contact with the outer surface of the rotor core. The non-magnetic cover formed in the process is press-fitted. In this way, the permanent magnet is firmly held by the small diameter portion. Further, the large diameter portion suppresses the pressure input during the cover press-fitting process from becoming too strong, and prevents the non-magnetic cover from buckling. In addition, since the inner surface of the large diameter part abuts on the outer surface of the permanent magnet, it is possible to prevent the large diameter part from increasing the maximum outer diameter of the entire rotor, and the large diameter part is a stator facing the rotor. It is possible to prevent the gap from becoming large.

According to this method, in the cover press-fitting step, the non-magnetic cover is press-fitted from the large diameter portion side, so that the press-fitting is easier than the method of press-fitting from the small diameter portion side.
According to this method, the rotor core is configured by arranging a high-hardness portion having a high hardness and a low-hardness portion having a low hardness side by side in the axial direction. Since it is press-fitted, deformation of the rotor core can be suppressed as compared with the case where it is press-fitted from the low hardness portion side.

In the non-magnetic cover molding step of the rotor manufacturing method, it is preferable to mold a reduced diameter portion whose inner diameter gradually decreases between the large diameter portion and the small diameter portion.
According to the same method, in the non-magnetic cover molding step, a reduced diameter portion whose inner diameter gradually decreases is formed between the large diameter portion and the small diameter portion. Therefore, in the cover press-fitting step, the large diameter portion to the small diameter portion is formed. It is press-fitted smoothly and becomes easy to press-fit.

In the production how the rotor of the present invention, it is possible to firmly hold the easily permanent magnets.

The schematic cross-sectional view which shows the schematic structure of the motor in one Embodiment. An exploded perspective view of the motor in one embodiment. (A) is a side view of the motor in one embodiment, and (b) is a sectional view taken along line bb. FIG. 5 is a cross-sectional view showing a stator core and a rotor according to an embodiment. Explanatory drawing for demonstrating the manufacturing method of the motor in one Embodiment. Explanatory drawing for demonstrating the manufacturing method of a rotor in one Embodiment. (A) and (b) are partially enlarged cross-sectional views of the rotor in one embodiment.

Hereinafter, one embodiment will be described with reference to FIGS. 1 to 7.
As shown in FIG. 1, the motor 10 rotates an annular stator 13 by a first end frame (hereinafter referred to as a first frame 11) and a second end frame (hereinafter referred to as a second frame 12). It is configured to be sandwiched in the direction. The first frame 11 and the second frame 12 are fixed to each other by a plurality of (two in this embodiment) through bolts 14 arranged on the outer periphery of the stator 13. Further, the rotor 15 is rotatably arranged inside the stator 13. In the present embodiment, the end frame that holds the stator 13 on the axially counter-output side (upper side in FIG. 1) of the motor 10 is the first frame 11, and the end frame that holds the stator 13 on the axial output side is the first frame. It is set to 2 frames 12.

As shown in FIGS. 1 and 2, the stator 13 has an annular stator core 16 and a coil 17 wound around the stator core 16. As shown in FIG. 3B, the stator core 16 includes an annular portion 16a forming an annular shape, a plurality of teeth 16b extending radially inward from the annular portion 16a and arranging in the circumferential direction (60 in the present embodiment). It is composed of four core outer peripheral protrusions 16c that protrude outward in the radial direction from the outer peripheral surface of the annular portion 16a and extend along the axial direction. The outer peripheral surface of the annular portion 16a has a cylindrical shape, and both end surfaces of the annular portion 16a in the axial direction have a planar shape orthogonal to the axial direction. Further, the coil 17 is wound so as to straddle the plurality of teeth 16b.

As shown in FIGS. 3A and 3B, the core outer peripheral protrusions 16c are provided at four locations having equal intervals (90 ° intervals in the present embodiment) in the circumferential direction on the outer peripheral surface of the annular portion 16a. It is provided in. Each core outer peripheral protrusion 16c forms a ridge extending along the axial direction from one end to the other end of the annular portion 16a in the axial direction, and the shape seen from the axial direction becomes circumferential as it goes from the base end to the tip end. It has a substantially trapezoidal shape with a narrow width. Further, each core outer peripheral protrusion 16c is formed with an arc recess 16d recessed from the tip end (radial outer end) of each core outer peripheral protrusion 16c toward the base end. The arcuate recess 16d has an arcuate shape when viewed from the axial direction, and has a groove shape that penetrates the core outer peripheral protrusion 16c in the axial direction. The radius of curvature of the arc recess 16d is slightly larger than the radius of the male screw-shaped portion of the through bolt 14. Then, of the four core outer peripheral protrusions 16c, two core outer peripheral protrusions 16c provided at two locations at 180 ° intervals in the circumferential direction (two core outer peripheral protrusions 16c provided on the left and right in FIG. 3B). In the arc recess 16d of 16c), a through bolt 14 having a substantially cylindrical shape extending in the axial direction is arranged. These two core outer peripheral protrusions 16c surround about half of the outer circumference of the through bolt 14 when viewed from the axial direction.

As shown in FIG. 1, the stator core 16 is formed by laminating a plurality of stator core sheets 18 formed by punching an electromagnetic steel plate material by press working in the axial direction and caulking them together. L-shaped cores 66 having an L-shaped cross section are attached to both ends of the stator core 16 in the axial direction, which are provided with rotor facing portions 65 extending in the radial direction and outward in the axial direction.

Therefore, while keeping the stacking thickness of the stator core 16 (the thickness of the laminated stator core sheet 18 and the entire L-shaped core 66) small, the axial length of the radial inner end surface 16e (opposing surface to the rotor 15) of the teeth 16b. It is possible to secure. In FIG. 3A, the stator core sheet 18 is omitted to simplify the stator core 16.

As shown in FIGS. 1 and 2, the first frame 11 and the second frame 12 arranged on both sides of the stator core 16 in the axial direction are made of a metal material and are formed by casting. The first and second frames 11 and 12 have a substantially disk-shaped first and second main body portions 21 and 31, and a cylindrical first body extending axially from the first and second main body portions 21 and 31. The second stator holding portions 22 and 32 are provided, respectively. Further, a plurality of first and second frames 11 and 12 are integrally provided on the outer peripheral surfaces of the first and second stator holding portions 22 and 32 and the first and second main body portions 21 and 31 (in the present embodiment). It is provided with first and second bolt fastening portions 23 and 33 (two each). The first and second bolt fastening portions 23 and 33 are provided at equal angular intervals (180 ° intervals in this embodiment) in the circumferential direction. Further, each first bolt fastening portion 23 is formed with a first fastening hole 23a (see FIG. 2) into which the through bolt 14 is inserted, and each second bolt fastening portion 33 is screwed with the through bolt 14. A female screw-shaped second fastening hole 33a (see FIG. 3B) to be combined is formed. In the first frame 11 and the second frame 12, the first and second bolt fastening portions 23 and 33 are connected to each other by a through bolt 14 that penetrates the first fastening hole 23a and is screwed into the second fastening hole 33a. Are fixed and integrated with each other. Further, the second frame 12 has a fixing portion 34 for fixing the motor 10 to an external fixing place with a screw (not shown). The fixing portion 34 extends radially outward from two positions deviated in the circumferential direction from the two second bolt fastening portions 33 in the second main body portion 31. The motor 10 is fixed at a fixed place so that the second frame 12 is located below the first frame 11, for example.

As shown in FIGS. 2 and 3A, one end portion in the axial direction (the upper end portion in FIG. 3A) of the stator core 16 is fitted inward in the radial direction at the tip end portion of the first stator holding portion 22. The formed first fitting portion 25 is formed. Similarly, at the tip of the second stator holding portion 32, a second fitting portion 35 in which the other end portion (lower end portion in FIG. 3A) in the axial direction of the stator core 16 is fitted radially inward is provided. It is formed.

The first fitting portion 25 is composed of a plurality of (four in the present embodiment) first fitting walls 25a arranged apart from each other in the circumferential direction. The four first fitting walls 25a are provided at equal angular intervals (90 ° intervals in the present embodiment) in the circumferential direction. Further, the four first fitting walls 25a are arranged one by one between the core outer peripheral protrusions 16c adjacent to each other in the circumferential direction. That is, the core outer peripheral protrusion 16c is located between the first fitting walls 25a adjacent to each other in the circumferential direction and overlaps the first fitting wall 25a in the circumferential direction. The core outer peripheral protrusion 16c does not overlap with the first fitting wall 25a in the radial direction. Further, the second fitting portion 35 is composed of a plurality of (eight in this embodiment) second fitting walls 35a arranged apart from each other in the circumferential direction. The second fitting wall 35a is arranged on both sides of each core outer peripheral protrusion 16c in the circumferential direction (that is, two each between the core outer peripheral protrusions 16c adjacent to each other in the circumferential direction). That is, the core outer peripheral protrusion 16c is located between the second fitting walls 35a adjacent to each other in the circumferential direction and overlaps the second fitting wall 35a in the circumferential direction. The core outer peripheral protrusion 16c does not overlap with the second fitting wall 35a in the radial direction.

The first and second fitting portions 25, 35 (first and second fitting walls 25a, 35a) are radially thicker than the proximal end side portions of the first and second stator holding portions 22, 32. Is thinly formed. Further, the first and second fitting walls 25a and 35a extend in parallel with the axial direction and form an arc shape along the circumferential direction when viewed from the axial direction. Further, the width of each of the first and second fitting walls 25a and 35a in the circumferential direction becomes narrower from the base end toward the tip end (the tip end side ends of the first and second stator holding portions 22 and 35). ..

As shown in FIG. 1, the inner peripheral surfaces of the first and second fitting portions 25 and 35, that is, the radial inner side surfaces of the first and second fitting walls 25a and 35a, respectively, are the first and second frames. The first and second centering surfaces 25b and 35b for centering the 11 and 12 and the stator core 16 are provided.

Further, the first and second frames 11 and 12 are adjacent to the base end portions of the first and second fitting portions 25 and 35 in a direction orthogonal to the central axes of the first and second stator holding portions 22 and 32. It has first and second contact surfaces 26, 36. An axial end surface (upper end surface in FIG. 1) of the annular portion 16a fitted into the first fitting portion 25 is in axial contact with the first contact surface 26. Further, the other end surface (lower end surface in FIG. 1) of the annular portion 16a fitted in the second fitting portion 35 in the axial direction is in axial contact with the second contact surface 36. In this state, the first frame 11 and the second frame 12 are fixed to each other by the through bolt 14 while sandwiching the stator 13 between the first and second stator holding portions 22 and 32.

In the present embodiment, the first and second fitting portions 25, 35 (first and second fitting walls 25a, 35a) provided at the tip portions of the first and second stator holding portions 22, 32 are , Protrudes in the axial direction from the first and second contact surfaces 26, 36. Therefore, in the first frame 11, the first centering surface 25b and the first contact surface 26 are close to each other at a right angle, and in the second frame 12, the second centering surface 35b and the second contact surface 36 are in contact with each other. They are close at right angles.

A bearing accommodating portion 29 is formed in the central portion of the first main body portion 21 so that the ball bearing B1 can be assembled from the stator 13 side (internal side of the motor 10) in the axial direction. The bearing accommodating portion 29 has a circular shape in the axial direction, and its inner peripheral surface has a cylindrical shape extending in the axial direction. Further, the central axis of the bearing accommodating portion 29 coincides with the central axis of the first stator holding portion 22 (the central axis of the first fitting portion 25). The first frame 11 accommodates and holds the annular ball bearing B1 in the bearing accommodating portion 29. Further, a through hole 29a is formed in the center of the bottom of the bearing accommodating portion 29 so as to penetrate the bottom portion of the bearing accommodating portion 29 in the axial direction. Then, the ball bearing B1 is axially urged toward the stator 13 between the radial outer portion of the through hole 29a at the bottom of the bearing accommodating portion 29 and the ball bearing B1 accommodated in the bearing accommodating portion 29. A wave washer 41 is interposed.

A bearing accommodating portion 40 for accommodating and holding an annular ball bearing B2 is recessed in the central portion of the second main body portion 31. The bearing accommodating portion 40 has a concave shape that is recessed from the axially outer end surface of the second frame 12 to the inner side (stator 13 side) of the motor 10. That is, the bearing accommodating portion 40 is formed so that the ball bearing B2 can be assembled from the outer side (opposite side to the stator 13) of the motor 10. Further, the central axis of the bearing accommodating portion 40 coincides with the central axis of the second stator holding portion 32 (the central axis of the second fitting portion 35). Then, the second frame 12 holds the ball bearing B2 arranged in the bearing accommodating portion 40 so as to be coaxial with the ball bearing B1 held in the first frame 11. Further, the ball bearing B2 is positioned in the axial direction by abutting the bottom portion of the bearing accommodating portion 40 from the axial direction. A through hole 40a is formed in the center of the bottom of the bearing accommodating portion 40 so as to penetrate the bottom portion of the bearing accommodating portion 40 in the axial direction.

The rotor 15 includes a rotating shaft 51 rotatably supported by ball bearings B1 and B2, a cylindrical rotor core 52 rotatably fixed to the rotating shaft 51, and a plurality of rotor cores 52 arranged on the outer surface of the rotor core 52. It includes a permanent magnet 53 and a tubular non-magnetic cover 54 that covers and holds the outer surface of each permanent magnet 53. Each permanent magnet 53 is radially opposed to the inner peripheral surface of the stator core 16 (the radial inner end surface 16e of the teeth 16b) via the non-magnetic cover 54. The tip end portion (lower end portion in FIG. 1) of the rotating shaft 51 penetrates the through hole 40a and protrudes from the ball bearing B2 to the outside of the second frame 12 and to the outside of the motor 10. A joint 55 (see FIG. 2) as a portion is attached. Further, the base end portion (upper end portion in FIG. 1) of the rotating shaft 51 penetrates the through hole 29a and protrudes to the outside of the first frame 11, and the protruding portion has a disk shape via the fixing member 56. The sensor magnet 57 is fixed.

As shown in FIGS. 1 and 2, the control unit 61 is fixed to the outer surface of the first frame 11. The control unit 61 includes a cover 62 fixed to the first frame 11 and a circuit board 63 housed inside the cover 62. Various elements including a magnetic sensor 63a and the like facing the sensor magnet 57 are mounted on the circuit board 63. Further, the end portion of the coil 17 is electrically connected to the circuit board 63. Further, a connector portion 64 to which an external connector (not shown) for supplying power to the motor 10 is connected is fixed to the circuit board 63, and the connector portion 64 is exposed to the outside of the cover 62. Then, the power supplied from the external connector is supplied to the coil 17 via the circuit board 63, so that the rotor 15 rotates.

Here, as shown in FIG. 4, the rotor core 52 of the rotor 15 of the present embodiment is configured by laminating a plurality of rotor core sheets 67. The plate thickness of each rotor core sheet 67 is the same as the plate thickness of the stator core sheet 18. Then, in order to make the outer peripheral surface of the rotor core 52 face the entire inner peripheral surface of the stator core 16 including the L-shaped core 66, the rotor core sheet 67 has the same number of main rotor core sheets 67a as the number of laminated stator core sheets 18 and supplements for the shortage. It is composed of a rotor core sheet 67b.

The main rotor core sheet 67a is formed of an electromagnetic steel plate material common to the stator core sheet 18 by press working. That is, as shown in FIG. 5, the stator core sheet 18 and the main rotor core sheet 67a are formed one by one from the common electromagnetic steel plate material 68 by press working.

The auxiliary rotor core sheet 67b is formed by punching a spcc material (cold rolled steel plate) that is softer (lower hardness) than the electromagnetic steel plate material in a separate process.
In the rotor core 52, a high hardness portion 71 in which the main rotor core sheet 67a is laminated and a low hardness portion 72 in which the auxiliary rotor core sheet 67b is laminated are arranged side by side in the axial direction. It is configured.

Further, as shown in FIGS. 1 and 6, the rotating shaft 51 has a knurled portion 51a (not shown in FIG. 4) in which the rotor core 52 is externally fitted and fixed in the intermediate portion in the longitudinal direction (axial direction) thereof. The knurled portion 51a of the present embodiment is knurled so that a large number of grooves extending along the axial direction are provided in the circumferential direction. Further, the rotating shaft 51 has non-knurled portions 51b and 51c in which the knurled portions 51a are not formed on both end sides thereof, and the lengths of the non-knurled portions 51b and 51c are different from each other. The non-knurled portion 51b on the side where the sensor magnet 57 is fixed is formed longer than the non-knurled portion 51c on the other end side in the axial direction (lower end side in FIG. 1). The rotary shaft 51 is provided with groove portions 51d and 51e having different shapes on one end surface in the axial direction (upper end surface in FIG. 1) and the other end surface in the axial direction (lower end surface in FIG. 1). In the present embodiment, the groove portion 51d on one end surface in the axial direction of the rotating shaft 51 and the groove portion 51e on the other end surface in the axial direction of the rotating shaft 51 are circular groove portions having different diameters when viewed from the axial direction, and are in the axial direction. The groove portion 51d on one end surface is a circular groove portion having a larger diameter than the groove portion 51e on the other end surface in the axial direction. The rotating shaft 51 is arranged so that the longer non-knurled portion 51b (on the one end side in the axial direction and on the side where the groove portion 51d having a large diameter is formed) is arranged on the high hardness portion 71 side of the rotor core 52. The knurled portion 51a is fixed to the rotor core 52 in a state of being press-fitted into the rotor core 52.

Further, as shown in FIG. 3B, a plurality of permanent magnets 53 (10 in this embodiment) are provided in the circumferential direction in contact with the outer surface (outer peripheral surface) of the rotor core 52.
As shown in FIGS. 7 (a) and 7 (b), the permanent magnet 53 has a circumferential central portion on the outer surface (diameter outer surface) of the permanent magnet 53 as compared to both peripheral portions. It has a curved shape that is far from the axis center L1. Specifically, the permanent magnet 53 is arranged so as to be in contact with the outer surface of the rotor core 52, and the distance K1 from the axis center L1 to the circumferential center on the outer surface is the circumferential direction from the axis center L1 to the outer surface. It is formed in a curved shape that is farther (larger) than the distance K2 to the end. Further, as shown in FIG. 7A, the permanent magnet 53 of the present embodiment has a magnetic flux (see arrow A) passing through an orientation point Z on the outer surface thereof which is radially outside the central portion in the circumferential direction. It is magnetized (reversely radial).

Further, the tubular non-magnetic cover 54 covering the outer surface of each permanent magnet 53 has a high-pressure contact portion 54a (see FIG. 7A) and a low-pressure contact portion 54b (see FIG. 7B) in the axial direction thereof. Has. The high-pressure contact portion 54a is arranged on the high-hardness portion 71 side (upper side in FIG. 4) of the rotor core 52, and as shown in FIG. 7A, has a wide range W1 in the circumferential direction and a high pressure on the outer surface of the permanent magnet 53. Press with. Further, the low pressure contact portion 54b is arranged on the low hardness portion 72 side (lower side in FIG. 4) of the rotor core 52, and as shown in FIG. 7 (b), has a narrow range W2 in the circumferential direction on the outer surface of the permanent magnet 53. Pressure contact at low pressure (almost point contact when viewed from the axial direction).

Next, a method for manufacturing the rotor 15 configured as described above and its operation will be described.
The method for manufacturing the rotor 15 of the present embodiment includes a "shaft press-fitting process", a "non-magnetic cover molding process", a "cover press-fitting process" and the like.

As shown in FIG. 6, in the “shaft press-fitting step”, the rotating shaft 51 is inserted from the low hardness portion 72 side, and the knurled portion 51a is press-fitted into the rotor core 52 configured as described above. At this time, the rotating shaft 51 is inserted into the rotor core 52 from the longer non-knurled portion 51b side on which one end side in the axial direction (upper end side in FIG. 6) and in which a circular groove portion 51d having a large diameter is formed. ..

Further, as shown in FIG. 6, in the "non-magnetic cover molding step", as described above, the tubular non-magnetic cover 54 covering the outer surface of each permanent magnet 53 has a large inner diameter (later, a low-pressure contact portion). A non-magnetic cover 54 is formed in which a large-diameter portion 81 (which becomes 54b) and a small-diameter portion 82 (which later becomes a high-pressure contact portion 54a) having a small inner diameter are arranged side by side in the axial direction. Further, in the "non-magnetic cover molding step" of the present embodiment, a reduced diameter portion 83 whose inner diameter gradually decreases is formed between the large diameter portion 81 and the small diameter portion 82. Further, in the "non-magnetic cover molding step" of the present embodiment, the guide diameter-expanded portion 84 whose inner diameter gradually increases is formed on the opening end side of the large-diameter portion 81.

Then, in the subsequent "cover press-fitting step", the inner surface of the large diameter portion 81 and the inner surface of the small diameter portion 82 are both outside the permanent magnet 53 in a state where the permanent magnet 53 is in contact with the outer surface of the rotor core 52. The non-magnetic cover 54 molded in the "non-magnetic cover molding step" is press-fitted so as to come into contact with the surface (a strong pressure is applied so as to cover the non-magnetic cover 54 and the non-magnetic cover is pushed in the axial direction). In the "cover press-fitting step" of the present embodiment, the non-magnetic cover 54 is press-fitted from the large diameter portion 81 side of the non-magnetic cover 54 and from the guide diameter enlarged portion 84 side. Further, in the "cover press-fitting step" of the present embodiment, the non-magnetic cover 54 is press-fitted from the high hardness portion 71 side. In this way, the non-magnetic cover 54 is (lightly) press-fitted so that the large-diameter portion 81 first covers each permanent magnet 53 while being smoothly guided by the guide diameter-expanded portion 84, and is smoothly guided by the diameter-reduced portion 83 in the middle. The small diameter portion 82 is press-fitted so as to cover each permanent magnet 53 while being guided by. Then, the large diameter portion 81 becomes the above-mentioned low-pressure contact portion 54b, and the small-diameter portion 82 is greatly deformed to become the above-mentioned high-pressure contact portion 54a. In this way, the rotor 15 is manufactured.

Next, the characteristic effects of the above embodiment will be described below.
(1) In the "molding step", a non-magnetic cover 54 in which a large diameter portion 81 having a large inner diameter and a small diameter portion 82 having a small inner diameter are arranged side by side in the axial direction is molded. Then, in the "cover press-fitting step", the inner surface of the large diameter portion 81 and the inner surface of the small diameter portion 82 both come into contact with the outer surface of the permanent magnet 53 in a state where the permanent magnet 53 is in contact with the outer surface of the rotor core 52. The non-magnetic cover 54 molded in the "non-magnetic cover molding step" is press-fitted into the. In this way, the permanent magnet 53 is firmly held by the small diameter portion 82 (later, the high-voltage contact portion 54a). Further, the large diameter portion 81 suppresses the pressure input during the "cover press-fitting process" from becoming too strong, and prevents the non-magnetic cover 54 from buckling. Further, since the inner surface of the large diameter portion 81 (later the low pressure contact portion 54b) also comes into contact with the outer surface of the permanent magnet 53, the portion of the large diameter portion 81 (low pressure contact portion 54b) increases the maximum outer diameter of the entire rotor 15. It is possible to prevent the large diameter portion 81 (low pressure contact portion 54b) from increasing the gap between the rotor 15 and the stator 13 facing the rotor 15.

(2) In the "cover press-fitting step", since the non-magnetic cover 54 is press-fitted from the large diameter portion 81 side, it is easier to press-fit than the method of press-fitting from the small diameter portion 82 side.
(3) In the "non-magnetic cover molding step", a reduced diameter portion 83 whose inner diameter gradually decreases is formed between the large diameter portion 81 and the small diameter portion 82. Therefore, in the "cover press-fitting step", the large diameter portion 81 is formed. Is smoothly press-fitted into the small diameter portion 82, which facilitates press-fitting.

(4) The rotor core 52 is composed of a high hardness portion 71 having a high hardness and a low hardness portion 72 having a low hardness arranged side by side in the axial direction. In the “cover press-fitting step”, the non-magnetic cover 54 has a high hardness. Since the press-fitting is performed from the portion 71 side, deformation of the rotor core 52 can be suppressed as compared with the case where the press-fitting is performed from the low hardness portion 72 side.

(5) The non-magnetic cover 54 has a high-pressure contact portion 54a that presses against a wide range W1 in the circumferential direction of the permanent magnet 53 at a high pressure and a low-pressure contact portion 54a that presses against a narrow range W2 in the circumferential direction of the permanent magnet 53 at a low pressure. Since the 54b and the 54b are arranged side by side in the axial direction, the permanent magnet 53 is firmly held by the high-pressure contact portion 54a. Further, the low-pressure contact portion 54b suppresses the pressure input during assembly (cover press-fitting step) from becoming too strong, and prevents the non-magnetic cover 54 from buckling. Further, since the low-pressure contact portion 54b also comes into contact with the outer surface of the permanent magnet 53, it is possible to prevent the portion of the low-pressure contact portion 54b from increasing the maximum outer diameter of the entire rotor 15, and the low-pressure contact portion 54b becomes the rotor 15. It is possible to prevent the gap between the stator 13 and the facing stator 13 from being increased.

The above embodiment may be modified as follows.
-In the "cover press-fitting step" of the above embodiment, the non-magnetic cover 54 is press-fitted from the large diameter portion 81 side, but the present invention is not limited to this, and press-fitting may be performed from the small diameter portion 82 side. In this case, the guide diameter expansion portion 84 is preferably formed at the open end of the small diameter portion 82.

-In the "non-magnetic cover molding step" of the above embodiment, the reduced diameter portion 83 whose inner diameter gradually decreases is formed between the large diameter portion 81 and the small diameter portion 82, but the diameter is not limited to this. It is not necessary to mold the part 83.

-In the above embodiment, the rotor core 52 is configured by having a high hardness portion 71 having a high hardness and a low hardness portion 72 having a low hardness arranged side by side in the axial direction, but the rotor core 52 is not limited to this, for example. A rotor core having a constant hardness in the axial direction may be used.

-In the "cover press-fitting step" of the above embodiment, the non-magnetic cover 54 is press-fitted from the high hardness portion 71 side, but the present invention is not limited to this, and the non-magnetic cover 54 may be press-fitted from the low hardness portion 72 side.

52 ... rotor core, 53 ... permanent magnet, 54 ... non-magnetic cover, 54a ... high pressure contact part, 54b ... low pressure contact part, 71 ... high hardness part, 72 ... low hardness part, 81 ... large diameter part, 82 ... small diameter part, 83 ... Reduced diameter part, L1 ... Axis center.

Claims (2)

With the rotor core
A curved permanent magnet that is provided in contact with the outer surface of the rotor core in the circumferential direction, and the central portion of the outer surface in the circumferential direction is farther from the axial center than both ends in the circumferential direction when viewed from the axial direction.
A method for manufacturing a rotor including a tubular non-magnetic cover that covers the outer surface of each of the permanent magnets.
A non-magnetic cover molding step of molding the non-magnetic cover in which a large-diameter portion having a large inner diameter and a small-diameter portion having a small inner diameter are arranged side by side in the axial direction.
In a state where the permanent magnet is in contact with the outer surface of the rotor core, the inner surface of the large diameter portion and the inner surface of the small diameter portion are both formed in the non-magnetic cover molding step so as to be in contact with the outer surface of the permanent magnet. The cover press-fitting process for press-fitting the non-magnetic cover is provided.
In the cover press-fitting step, the non-magnetic cover is press-fitted from the large diameter side and is press-fitted.
The rotor core is composed of a high hardness portion having a high hardness and a low hardness portion having a low hardness arranged side by side in the axial direction.
A method for manufacturing a rotor, wherein in the cover press-fitting step, the non-magnetic cover is press-fitted from the high hardness portion side. The method for manufacturing a rotor according to claim 1.
A method for manufacturing a rotor, characterized in that, in the non-magnetic cover molding step, a reduced diameter portion whose inner diameter gradually decreases is formed between the large diameter portion and the small diameter portion.

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