JP7053240B2 - Electric motor - Google Patents

Description

The present invention relates to a technical field of a motor comprising a stator and a rotor that is rotated relative to the stator.

The rotor provided in the electric motor has a shaft serving as a rotation fulcrum and a rotor core into which the shaft is inserted and rotated together with the shaft. In an electric motor mounted on a vehicle such as an electric vehicle, there is generally a minute gap between the shaft and the rotor core to allow the shaft to be inserted.

By the way, in order to maintain a stable rotational state of the rotor, it is desirable that the rotation axes of the shaft and the rotor core are coaxial and the rotation phases of the shaft and the rotor core are the same. However, since there is a gap between the shaft and the rotor core, there is a concern that the rotation axis and the rotation phase of the shaft and the rotor core may shift due to this gap.

Therefore, a technique for reducing the influence of the gap existing between the shaft and the rotor core is known. For example, in Patent Document 1, by arranging a spring between the shaft and the rotor core, the deviation of the rotation shaft between the shaft and the rotor core is suppressed. There is also an example in which the rotor core is fixed to the shaft by shrink-fitting the rotor core to the shaft so that the rotation axis and the rotation phase of the rotor core and the shaft match.

Japanese Unexamined Patent Publication No. 6-261476

However, when an intermediate member such as a spring is arranged between the shaft and the rotor core, it is difficult to accurately match the rotational phases of the shaft and the rotor core due to the deformation of the spring. Further, when the shaft and the rotor core are fixed by shrink fitting, there is a problem that the manufacturing cost increases because the equipment for heating the member and the processing of the heated member are required.

Therefore, an object of the present invention is to secure a stable rotational state of the rotor with respect to the stator while suppressing an increase in manufacturing cost.

The electric motor according to the present invention is an electric motor including a stator and a rotor rotated with respect to the stator, and the rotor includes a shaft serving as a rotation fulcrum and a rotor core into which the shaft is inserted. , The rotor core has a plurality of fixing members for fixing the rotor core to the shaft, the rotor core has two first core portions and a second core portion, and the two first core portions. The rotor core is provided as both ends in the axial direction, the second core portion is located between the two first core portions, and the plurality of fixing members are evenly spaced in the circumferential direction of the rotor. The shaft is formed with a plurality of first fixing grooves opened on the rotor core side in a direction orthogonal to the axial direction, and the two first core portions are orthogonal to the axial direction. A plurality of second fixing grooves opened on the shaft side in the direction are formed, and the fixing member is press-fitted between the shaft and one of the first core portions , and the first is in a state of being press -fitted. At least two points are in contact with the first wall surface forming the fixing groove of the above, and at least two points are contacted with the second wall surface forming the second fixing groove, and the shaft is attached to the second core portion. A protruding portion is provided on the side, and an insertion groove into which the protruding portion is inserted is formed in the shaft .

As a result, a plurality of fixing members located at equal intervals in the circumferential direction are press-fitted into contact with the shaft and the rotor core at least two points each, so that the rotor core is fixed in a state of being positioned on the shaft by the fixing member. To.
Further, the protruding portion of the rotor core is inserted into the insertion groove of the shaft, and the rotor core is positioned on the shaft in the circumferential direction.

In the above-mentioned electric motor, the fixing member has a circular cross-sectional shape in a direction orthogonal to the axial direction, and the first wall surface is a pair of the fixing members that move away from each other as they approach the rotor core and come into contact with the fixing member. It is desirable that an inclined surface is formed, and a pair of inclined surfaces are formed on the second wall surface as they approach the shaft and move away from each other so that the fixing member is in contact with the inclined surface.

As a result, the fixing member having a circular cross-sectional shape in the direction orthogonal to the axial direction is press-fitted between the shaft and the rotor core in a state of being in contact with the inclined surface.

In the above-mentioned electric motor, it is desirable that the fixing member is formed in a spherical shape.

As a result, the spherical fixing member is press-fitted between the shaft and the rotor core.

In the above-mentioned motor, it is desirable that two of the fixing members are provided.

As a result, the two fixing members are positioned 180 ° apart in the circumferential direction.

In the above-mentioned electric motor, it is desirable that a pressed surface on which the fixing member is pressed is formed on one of the first core portions in the axial direction.

This allows the fixing member to be inserted between the shaft and the rotor core to a position where it is pressed against the pressed surface.

According to the present invention, since a plurality of fixing members located at equal intervals in the circumferential direction are press-fitted into contact with the shaft and the rotor core at least two points each, the rotor core is positioned on the shaft by the fixing members. It is fixed with. Therefore, the phase shift between the shaft and the rotor core is prevented, the rotation axes of the shaft and the rotor core are aligned so as to be coaxial, and the torque transmission efficiency from the rotor core to the shaft is improved, so that the stator of the rotor is fixed. It is possible to secure a stable rotation state with respect to.

2 to 6 show an embodiment of the motor of the present invention, and this figure is an exploded perspective view of the motor. It is sectional drawing of the 1st core part of a rotor core. It is sectional drawing which shows the rotor by line III-III of FIG. It is sectional drawing of the 2nd core part of a rotor core. This is a modification of the first fixing groove, the second fixing groove, and the fixing member. This is a modification of the fixing member.

<Motor configuration>
Hereinafter, embodiments for carrying out the electric motor of the present invention will be described with reference to the accompanying drawings.

The electric motor 100 is mounted on an electric-powered vehicle such as an electric vehicle or a hybrid electric vehicle, and is used as a drive motor.

The electric motor 100 has a housing 1, a stator 2, a rotor 3 rotated with respect to the stator 2, and a resolver 4 for detecting the rotation angle of the rotor 3 (see FIG. 1).

The housing 1 has a box-shaped case body 5 opened on one side and a cover body 6 that closes the opening 5a of the case body 5. The internal space of the housing 1 is formed as a storage space 1a in which the stator 2, the rotor 3, and the resolver 4 are housed.

The case body 5 is formed with a mounting hole 5b at the center of the end opposite to the opening 5a. A mounting hole 6a is formed in a substantially central portion of the cover body 6 so as to penetrate in the same direction as the mounting hole 5b.

The stator 2 has a cylindrical stator core 2a and a coil (not shown) wound around the stator core 2a. The stator core 2a is formed, for example, by laminating a plurality of electromagnetic steel sheets.

The rotor 3 has a shaft 7 as a rotation fulcrum and a cylindrical rotor core 8 into which the shaft 7 is inserted and rotated together with the shaft 7. The rotor core 8 is formed, for example, by laminating a plurality of electromagnetic steel sheets. Inside the rotor core 8, a magnetic material such as a magnet (not shown) is arranged.

Bearings 9 and 9 are attached to both ends of the shaft 7 in the axial direction, respectively. The bearings 9 and 9 are attached to the case body 5 and the cover body 6 with the outer ring inserted into the mounting hole 5b and the mounting hole 6a, and the inner ring is attached to the shaft 7. Therefore, the shaft 7 is rotatably supported with respect to the housing 1 via the bearings 9 and 9. The bearings 9 and 9 have a function of smoothly rotating the shaft 7 by receiving the load of the shaft 7.

The resolver 4 has a cylindrical resolver stator 4a and a resolver rotor 4b arranged inside the resolver stator 4a. The resolver stator 4a is fixed to the inner surface of the cover body 6, and the resolver rotor 4b is attached to the rotor 3. The resolver rotor 4b is fixed to a part of the shaft 7 and is rotated together with the shaft 7.

<Rotor configuration>
Subsequently, the configuration of the rotor 3 will be described in detail with reference to FIGS. 1 to 3.

First, the configuration of the shaft 7 will be described. The shaft 7 has a main body portion 10 extending in the axial direction of the rotor 3 and a flange portion 11 protruding outward from a portion closer to one end in the axial direction of the main body portion 10 (see FIG. 3). .. One end surface of the flange portion 11 in the axial direction is formed as an abutting surface 11a to which a part of the rotor core 8 is abutted.

The main body portion 10 has small diameter portions 12 and 12 and a large diameter portion 13. The small diameter portions 12 and 12 are provided as both ends of the main body portion 10 in the axial direction. The large diameter portion 13 is located between the small diameter portions 12 and 12. The central axes of the small diameter portions 12 and 12 and the large diameter portion 13 are aligned. A resolver rotor 4b is attached to one of the small diameter portions 12, and the large diameter portion 13 is inserted into the rotor core 8 (see FIG. 1).

First fixing grooves 14, 14 opened on the rotor core 8 side in the radial direction are formed on the outer peripheral side of the large diameter portion 13 (see FIGS. 2 and 3). The first fixing grooves 14 and 14 extend in the axial direction, respectively, and are positioned 180 ° apart in the circumferential direction.

The first fixing groove 14 is formed by the first wall surface 15. The first wall surface 15 is composed of bottom surfaces 15a and 15a, side surfaces 15b and 15b, and inclined surfaces 15c and 15c. The bottom surfaces 15a and 15a face the rotor core 8 side and are positioned apart from each other in the width direction of the first fixing groove 14. The side surfaces 15b and 15b are orthogonal to the bottom surfaces 15a and 15a, one end thereof is continuous with the outer edge of the bottom surfaces 15a and 15a, and the other end is continuous with the outer peripheral surface of the shaft 7. The inclined surfaces 15c and 15c are located between the bottom surfaces 15a and 15a. One end of the inclined surfaces 15c and 15c is continuous with the inner edge of the bottom surfaces 15a and 15a, and the other end is aligned. The inclined surfaces 15c and 15c are inclined so as to move away from each other as they approach the rotor core 8.

Next, the configuration of the rotor core 8 will be described. The rotor core 8 has a first core portion 16, 16 and a second core portion 17. The first core portions 16 and 16 are provided as both end portions of the rotor core 8 in the axial direction. The second core portion 17 is located between the first core portions 16 and 16, and both end faces in the axial direction are in contact with the first core portions 16 and 16, respectively. The central axes of the first core portions 16 and 16 and the second core portion 17 are aligned.

On the inner peripheral side of the first core portions 16 and 16, second fixing grooves 18 and 18 opened on the shaft 7 side in the radial direction and extending in the axial direction are formed. The second fixing grooves 18 and 18 are located 180 ° apart in the circumferential direction.

The second fixing groove 18 is formed by the second wall surface 19. The second wall surface 19 is composed of inclined surfaces 19a and 19a. The inclined surfaces 19a and 19a are inclined so as to move away from each other as they approach the shaft 7. The second fixing grooves 18 and 18 are formed in a wedge shape in a cross-sectional shape orthogonal to the axial direction.

On the inner peripheral side of the second core portion 17, projecting portions 17a and 17a projecting toward the shaft 7 in the radial direction and extending in the axial direction are provided (see FIG. 4). The protrusions 17a and 17a are positioned 180 ° apart in the circumferential direction. The protrusions 17a and 17a have a substantially rectangular cross-sectional shape orthogonal to the axial direction. The protrusions 17a and 17a are provided at the same positions as the second fixing grooves 18 and 18, respectively, in the circumferential direction of the rotor core 8.

<Fixed structure of shaft and rotor core>
The large diameter portion 13 of the shaft 7 is inserted into the rotor core 8. When the shaft 7 is inserted into the rotor core 8, the protrusions 17a and 17a are inserted into the first fixing grooves 14 and 14, respectively, and the shaft 7 is positioned in the circumferential direction with respect to the rotor core 8. When the shaft 7 is inserted into the rotor core 8, one end surface 8a of the rotor core 8 in the axial direction is abutted against the abutting surface 11a of the flange portion 11 (see FIG. 3). By abutting the end surface 8a against the abutting surface 11a, the shaft 7 is positioned in the axial direction with respect to the rotor core 8.

When the shaft 7 is inserted into the rotor core 8, a gap S exists between the outer peripheral surface of the shaft 7 and the inner peripheral surface of the rotor core 8 (see FIGS. 2 and 4). Further, at this time, since the shaft 7 is positioned in the circumferential direction with respect to the rotor core 8 as described above, the first fixing grooves 14 and 14 and the second fixing grooves 18 and 18 are positioned so as to face each other. Has been done.

Fixing members 20 and 20 are press-fitted between the first fixing grooves 14 and 14 and the second fixing grooves 18 and 18 in the first core portion 15 (see FIGS. 2 to 4). The fixing members 20 and 20 are formed in a spherical shape, for example.

The fixing members 20 and 20 are in contact with the inclined surfaces 15c and 15c at the two contact points X and X, and are in contact with the inclined surfaces 19a and 19a at the two contact points Y and Y (see FIG. 2).

The fixing members 20 and 20 are pressed against the inner peripheral portion of one end surface of the second core portion 17 in the axial direction. The inner peripheral portion of the one end surface is formed as the pressed contact surfaces 17b and 17b, and the fixing members 20 and 20 are inserted to the positions where they are pressed against the pressed contact surfaces 17b and 17b (see FIG. 3).

In a state where the fixing members 20 and 20 are inserted between the shaft 7 and the rotor core 8 and press-fitted, the annular fixing ring 21 is externally fitted to the portion of the large diameter portion 13 of the shaft 7 near the other end. The fixing ring 21 has a function of restricting the movement of the rotor core 8 in the axial direction and preventing the fixing members 20 and 20 from falling off.

In the above configuration, the fixing members 20 and 20 are press-fitted between the shaft 7 and the rotor core 8, and the fixing members 20 and 20 are brought into contact with the first wall surface 15 of the first fixing groove 14 at two points X and X. At the same time, they are in contact with the second wall surface 19 of the second fixing groove 18 at two points Y and Y (see FIG. 2).

Therefore, since the plurality of fixing members 20 and 20 located at equal intervals in the circumferential direction are press-fitted in a state of being in contact with each other at two points between the shaft 7 and the rotor core 8, the rotor core 8 is pressed by the fixing members 20 and 20. It is fixed to the shaft 7 in a positioned state. As a result, the rotation phase shift between the shaft 7 and the rotor core 8 is prevented, the rotation axes of the shaft 7 and the rotor core 8 are aligned so as to be coaxial, and the torque transmission efficiency from the rotor core 8 to the shaft 7 is improved. , A stable rotational state of the rotor 3 with respect to the stator 2 can be ensured. By preventing the rotation phase shift between the shaft 7 and the rotor core 8, it is possible to prevent the shift of the current advance control flowing through the stator 2 of the motor 100 and suppress the deterioration of the motor efficiency, and also to suppress the deterioration of the motor efficiency. By aligning the rotating shafts of the rotor core 8 and the rotor core 8 so as to be in phase with each other, it is possible to improve the vibration performance of the motor 100. Further, by preventing the rotation phase shift between the shaft 7 and the rotor core 8, it is possible to improve the detection accuracy of the rotational state of the rotor 3 by the resolver 4.

Further, the fixing members 20 and 20 are formed in a spherical shape. As a result, the spherical fixing members 20 and 20 are press-fitted between the shaft 7 and the rotor core 8. Therefore, the press-fitting work of the fixing members 20 and 20 becomes easy, and the workability at the time of manufacturing the electric motor 100 can be improved.

Further, the electric motor 100 is provided with two fixing members 20 and 20 at equal intervals in the circumferential direction of the rotor 3. As a result, the two fixing members 20, 20 are positioned 180 ° apart in the circumferential direction. Therefore, the minimum number of fixing members 20 makes it possible to suppress the eccentricity of the shaft 7 and the rotor core 8, and it is possible to secure a stable rotational state of the rotor 3 with respect to the stator 2 with a small number of parts.

Furthermore, the second core portion 17 of the rotor core 8 is formed with pressed contact surfaces 17b and 17b to which the fixing members 20 and 20 are pressed at the time of press fitting. As a result, the fixing members 20 and 20 can be inserted between the shaft 7 and the rotor core 8 to a position where the fixing members 20 and 20 are pressed against the pressed contact surfaces 17b and 17b. Therefore, when the fixing members 20 and 20 are pressed against the pressed contact surfaces 17b and 17b, it becomes possible to recognize the completed state of the press-fitting work, and the fixing members 20 and 20 are surely placed between the shaft 7 and the rotor core 8. It can be press-fitted.

In addition, the rotor core 8 is provided with a protruding portion 17a protruding toward the shaft 7, and the protruding portion 17a is inserted into the first fixing groove 14. By inserting the protruding portion 17a of the rotor core 8 into the first fixing groove 14, the shaft 7 is positioned in the circumferential direction with respect to the rotor core 8. Therefore, the positioning of the first fixing groove 14 and the second fixing groove 18 in the circumferential direction can be easily performed.

In the above, an example in which the rotor core 8 has two first core portions 16 and 16 and a second core portion 17 is shown, but the fixing members 20 and 20 are press-fitted into the rotor core 8. It may have only one first core portion 16 and the second core portion 17. In this case, since the number of parts is reduced, the manufacturing cost of the motor 100 can be reduced. However, when the rotor core 8 is composed of the two first core portions 16 and 16 and the second core portion 17, the number of the second wall surface 19 formed on the rotor core 8 increases by that amount. , The rotor core 8 becomes lighter, and the weight of the electric motor 100 can be reduced.

<Modification example>
The above shows an example in which the first wall surface 15 of the first fixing groove 14 is composed of bottom surfaces 15a and 15a, side surfaces 15b and 15b, and inclined surfaces 15c and 15c, but the first wall surface 15 has another configuration. It may have been done.

For example, the first wall surface 15 may be composed of only inclined surfaces 15c and 15c. (See FIG. 5A). One end of the inclined surfaces 15c and 15c is continuous with the outer peripheral surface of the shaft 7, and the other ends coincide with each other. In this case, the cross-sectional shape of the first fixing groove 14 orthogonal to the axial direction is formed in a wedge shape.

Further, the above shows an example in which the fixing member 20 is press-fitted into the shaft 7 and the rotor core 8 in a state where the fixing member 20 is in contact with the shaft 7 and the rotor core 8 at two points each. It may be press-fitted in a state of being in contact with the contact point.

For example, the fixing member 20 may be in contact with the shaft 7 and the rotor core 8 at three points each (see FIG. 5B).

In the first fixing groove 14 shown in FIG. 5B, the first wall surface 15 is composed of a facing surface 15d and inclined surfaces 15e and 15e. The facing surface 15d faces the rotor core 8 side and is located at the center of the first fixing groove 14 in the width direction. One end of the inclined surfaces 15e and 15e is continuous with the outer peripheral surface of the shaft 7, and the other end is continuous with both end edges of the facing surface 15d. In the second fixing groove 18, the second wall surface 19 is composed of a facing surface 19b and an inclined surface 19c, 19c. The facing surface 19b faces the shaft 7 side and is located at the center of the second fixing groove 18 in the width direction. One end of the inclined surfaces 19c and 19c is continuous with the inner peripheral surface of the rotor core 8, and the other end is continuous with both end edges of the facing surface 19b. The fixing member 20 is in contact with the facing surface 15d and the inclined surfaces 15e, 15e at three contact points X, X, X, and at three contact points Y, Y, Y with the facing surface 19b and the inclined surfaces 19c, 19c. Being in contact.

Further, although the example in which the fixing member 20 is formed in a spherical shape is shown above, the fixing member 20 may be formed in a cylindrical shape or a cylindrical shape, for example.

When the fixing member 20 is formed in a columnar or cylindrical shape, the fixing member 20 is press-fitted between the shaft 7 and the rotor core 8 in a state where the axial direction is parallel to the rotation axis of the rotor 3. ..

As described above, when the fixing member 20 is formed in a spherical shape, a columnar shape, or a cylindrical shape, the cross-sectional shape of the fixing member 20 in the direction orthogonal to the axial direction is formed into a circular shape, and the fixing member 20 is the first. The pair of inclined surfaces 15c and 15c of the wall surface 15 and the pair of inclined surfaces 19a and 19a of the second wall surface 19 can be point-contacted. Therefore, the rotor core 8 can be fixed to the shaft 7 in a stable state.

The above shows an example in which the cross-sectional shape of the fixing member 20 is formed into a circular shape, and the fixing member 20 is in contact with the first wall surface 15 and the second wall surface 19 at least two points each. The fixing member 20, the first wall surface 15, and the second wall surface 19 are formed in other shapes as long as the member 20 is in contact with the first wall surface 15 and the second wall surface 19 at least two points each. May be good.

For example, instead of the fixing member 20, a fixing member 20A having an elliptical cross section is used, a pair of inclined surfaces 15c and 15c are formed on the first wall surface 15, and a pair of inclined surfaces are formed on the second wall surface 19. 19a and 19a may be formed (see FIG. 5C). In this case, the fixing member 20A is, for example, in contact with the inclined surfaces 15c and 15c, respectively, and is in contact with the inclined surfaces 19a and 19a at two points, respectively.

In the above, an example in which two fixing members 20 are provided is shown, but the number of the fixing members 20 is not limited to two, and three or more fixing members 20 are provided at equal intervals in the circumferential direction. You may. For example, the four fixing members 20, 20, 20, 20 may be positioned 90 ° apart in the circumferential direction (see FIG. 6). Even when three or more fixing members 20 are positioned at equal intervals in the circumferential direction as described above, the eccentricity of the shaft 7 and the rotor core 8 can be accurately suppressed.

1 ... Housing, 2 ... Stator, 3 ... Rotor, 7 ... Shaft, 8 ... Rotor core, 14 ... First fixing groove, 15 ... First wall part, 15c ... Inclined surface, 16 ... First core part , 17 ... second core portion, 17a ... protrusion, 18 ... second fixing groove, 19 ... second wall surface, 19a ... inclined surface, 20 ... fixing member

Claims (5)

An electric motor including a stator and a rotor that is rotated with respect to the stator.
The rotor has a shaft serving as a rotation fulcrum, a rotor core into which the shaft is inserted, and a plurality of fixing members for fixing the rotor core to the shaft.
The rotor core has two first core portions and a second core portion.
The two first core portions are provided as both ends in the axial direction of the rotor core.
The second core portion is located between the two said first core portions.
The plurality of fixing members are positioned at equal intervals in the circumferential direction of the rotor.
The shaft is formed with a plurality of first fixing grooves opened on the rotor core side in a direction orthogonal to the axial direction.
A plurality of second fixing grooves opened on the shaft side in a direction orthogonal to the axial direction are formed in the two first core portions .
The fixing member is press-fitted between the shaft and one of the first core portions , and is brought into contact with the first wall surface forming the first fixing groove in the press -fitted state at at least two points and said. Contacted at at least two points with the second wall surface forming the second fixing groove ,
The second core portion is provided with a protruding portion protruding toward the shaft side, and the second core portion is provided with a protruding portion.
The shaft is formed with an insertion groove into which the protrusion is inserted.
Electric motor. The fixing member has a circular cross-sectional shape in a direction orthogonal to the axial direction.
A pair of inclined surfaces are formed on the first wall surface as they approach the rotor core and move away from each other so that the fixing members come into contact with each other.
The motor according to claim 1, wherein a pair of inclined surfaces are formed on the second wall surface as they approach the shaft and move away from each other so that the fixing member is in contact with the second wall surface. The motor according to claim 2, wherein the fixing member is formed in a spherical shape. The motor according to claim 1, claim 2 or claim 3, wherein the two fixing members are provided. The motor according to claim 1, claim 2, claim 3 or claim 4, wherein a pressed surface on which the fixing member is pressed is formed on the first core portion .

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