Electric motor

Abstract

To suppress vibration transmission to a housing.SOLUTION: An electric motor comprises a housing, a stator stored in the housing, and a rotor provided with a hollow shaft supported by a bearing. The electric motor comprises an attachment member provided with a motor holding part for holding the stator and the rotor, a housing attachment part attached to the housing, and a connection part at which the motor holding part and the housing attachment part are connected with each other. The motor holding part comprises a rotor support part having a support shaft part arranged inside the hollow shaft, and supporting an inner ring of the bearing by the support shaft part. The motor holding part comprises a stator attachment part that extends radially outward from the rotor support part and is attached to the stator.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to electric motors. [Background technology]

[0002] Vehicles such as hybrid vehicles and electric vehicles are equipped with a motor generator, which is an electric motor. The motor generator has a stator fixed to a housing and a rotor rotatably supported by the housing (see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6590733 [Patent Document 2] JP 2018-50439 A [Patent Document 3] Patent No. 3786350 Summary of the Invention [Problem to be solved by the invention]

[0004] When the motor generator is driven, the stator vibrates due to magnetostriction, and the vibration is transmitted from the stator to the housing. Since the transmission of vibration from the stator to the housing increases the noise of the motor generator, there is a need to suppress the transmission of vibration from the stator to the housing. [Means for solving the problem]

[0005] According to the present disclosure, an electric motor includes a housing, a stator accommodated in the housing, and a rotor with a hollow shaft supported by a bearing. The electric motor includes a mounting member including a motor holding portion that holds the stator and the rotor, a housing mounting portion that is attached to the housing, and a connecting portion that connects the motor holding portion and the housing mounting portion to each other. The motor holding portion includes a rotor support portion that includes a support shaft portion that is disposed inside the hollow shaft and supports an inner ring of the bearing by means of the support shaft portion. The motor holding portion includes a stator mounting portion that extends radially outward from the rotor support portion and is attached to the stator. Effect of the Invention

[0006] According to the present disclosure, the transmission of vibration to the housing can be suppressed. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a vehicle equipped with a motor generator according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing an example of an internal structure of a power unit. [Diagram 3] 2 is a cross-sectional view showing a motor generator and its surroundings. [Figure 4] FIG. 2 is a cross-sectional view showing the motor generator in an exploded state. [Diagram 5] 2 is a cross-sectional view showing an exploded state of a motor assembly that constitutes a motor generator. FIG. [Figure 6] 6 is a view showing the mounting member as viewed from the direction of arrow VI in FIG. 5. [Figure 7A] 11A and 11B are diagrams illustrating an example of a deformation state of a mounting member. [Figure 7B] 11A and 11B are diagrams illustrating an example of a deformation state of a mounting member. [Figure 8] FIG. 11 is a cross-sectional view showing a motor generator according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or substantially the same configurations and elements will be denoted by the same reference numerals and repeated description will be omitted.

[0009] First Embodiment <Power unit> FIG. 1 is a diagram showing an example of a vehicle 10 equipped with a motor generator (electric motor) MG2 according to an embodiment of the present disclosure. As shown in FIG. 1, the vehicle 10 has a power unit 12 consisting of an engine 11 and motor generators MG1, MG2. A rear wheel output shaft 13 of the power unit 12 is connected to rear wheels 16 via a propeller shaft 14 and a rear differential mechanism 15. The power unit 12 also has a front differential mechanism 17, which is connected to front wheels 18. The illustrated power unit 12 is an all-wheel drive power unit, but is not limited thereto, and may be a front-wheel drive or rear-wheel drive power unit.

[0010] FIG. 2 is a diagram showing an example of the internal structure of the power unit 12. As shown in FIG. 2, the power unit 12 has a main output shaft 20 penetrating the center of the motor generator MG2 to output engine torque and motor torque to the front and rear wheels 16, 18. The main output shaft 20 is connected to a front wheel output shaft 22 via a gear train 21, and is connected to the rear wheel output shaft 13 via a transfer clutch 23. The main output shaft 20 is also connected to a power split mechanism 25 consisting of a planetary gear train via a gear train 24. The power split mechanism 25 is connected to the motor generator MG1, and is connected to the engine 11 via a gear train 26 and a torque converter 27. The main output shaft 20 is also connected to the motor generator MG2 via a planetary gear train 28. The front wheel output shaft 22 is connected to the front differential mechanism 17 described above.

[0011] <Motor generator MG2> Fig. 3 is a cross-sectional view showing motor generator MG2 and its vicinity. Fig. 4 is a cross-sectional view showing motor generator MG2 in an exploded state, and Fig. 5 is a cross-sectional view showing motor assembly 34 constituting motor generator MG2 in an exploded state. Fig. 6 is a view showing mounting member 70 as viewed from the direction of arrow VI in Fig. 5.

[0012] As shown in Figures 3 and 4, motor generator MG2 has a motor housing (housing) 30 consisting of a housing main body 31 and a partition wall 32. Motor generator MG2 also has a motor assembly 34 that is accommodated in motor housing 30 and fixed to partition wall 32 by mounting bolts 33. As shown in Figure 4, partition wall 32 of motor housing 30 is formed with an opening 35 for inserting main output shaft 20 and with a plurality of through holes 36 for inserting mounting bolts 33. Also, a flange portion 71 of mounting member 70 constituting motor assembly 34 is formed with screw holes (first bolt holes, bolt holes) 72 for inserting mounting bolts 33.

[0013] 3 and 5, the motor assembly 34 includes a stator 40 accommodated in the motor housing 30, a rotor 50 disposed inside the stator 40, and a mounting member 70 that holds the stator 40 and the rotor 50. The mounting member 70 is also called an adapter. The stator 40 of the motor assembly 34 includes a cylindrical stator core 41 made of a plurality of electromagnetic steel plates, and a three-phase stator coil 42 wound around the stator core 41. The stator core 41 is formed with a through hole 44 for inserting a mounting bolt 43.

[0014] The rotor 50 of the motor assembly 34 has a cylindrical rotor core 51 made of a plurality of electromagnetic steel plates, a plurality of permanent magnets 52 embedded in the rotor core 51, and a hollow rotor shaft (hollow shaft) 53 fixed to the center of the rotor core 51. A plurality of spline teeth are formed on the inner peripheral surface of one end 54 of the rotor shaft 53. An outer ring 57o of a bearing (first bearing) 57 is attached to an inner peripheral surface 56 formed on one end (first end) 54 of the rotor shaft 53. An inner ring 60i of a bearing (second bearing) 60 is attached to an outer peripheral surface 59 formed on the other end (second end) 58 of the rotor shaft 53.

[0015] The mounting member 70 of the motor assembly 34 has a motor holding portion 73 that holds the stator 40 and the rotor 50, a flange portion (housing mounting portion) 71 that is attached to the motor housing 30, and a connecting portion 74 that connects the motor holding portion 73 and the flange portion 71 to each other. As shown in Figs. 5 and 6, the motor holding portion 73 of the mounting member 70 has a rotor support portion 80 that rotatably supports the rotor 50, and a stator mounting portion 81 that is attached to the stator 40. The rotor support portion 80 has a support shaft portion 82 that is disposed inside the rotor shaft 53, and an annular wall portion 83 that expands radially outward from the support shaft portion 82. The support shaft portion 82 has an outer peripheral surface 84 for mounting the inner ring 57i of the bearing 57, and the annular wall portion 83 has an inner peripheral surface 85 for mounting the outer ring 60o of the bearing 60. The support shaft portion 82 has a through hole 86 for inserting the main output shaft 20. Furthermore, the stator mounting portion 81 of the mounting member 70 has a plurality of mounting arms 87 extending radially outward from the annular wall portion 83 of the rotor support portion 80. A screw hole (second bolt hole) 88 for inserting a mounting bolt 43 is formed at the tip of each mounting arm 87.

[0016] 3, an annular housing cover 90 is attached to the opening of the housing main body 31, and the sun gear 28s of the planetary gear train 28 is rotatably supported on the inner periphery of the housing cover 90 via a bearing 91. The rotor shaft 53 of the motor generator MG2 and the sun gear 28s of the planetary gear train 28 are connected to each other via an intermediate connecting shaft 92. A large diameter portion 93 of the intermediate connecting shaft 92 is formed with spline teeth 94 that mesh with the spline teeth 55 of the rotor shaft 53, and a small diameter portion 95 of the intermediate connecting shaft 92 is formed with spline teeth 96 that mesh with the spline teeth 29 of the sun gear 28s. In this manner, the intermediate connecting shaft (output shaft) 92 is connected to the rotor shaft 53 of the motor generator MG2 via the spline teeth 55, 94.

[0017] <Vibration suppression> When the motor generator MG2 is driven, vibrations of the stator 40 caused by magnetostriction are transmitted to the motor housing 30, which may result in noise being generated from the motor housing 30. Therefore, in order to suppress the transmission of vibrations to the motor housing 30, the motor generator MG2 does not adopt a structure in which the stator 40 is directly attached to the motor housing 30, but rather adopts a structure in which a mounting member 70 is interposed between the motor housing 30 and the stator 40.

[0018] As shown in FIG. 4, a flange portion 71 is connected to a motor holding portion 73 that holds the stator 40 and the rotor 50 via a connecting portion 74. The flange portion 71 of the mounting member 70 is attached to the partition wall 32 of the motor housing 30 by using a mounting bolt 33. By providing the mounting member 70 between the motor housing 30 and the stator 40 in this manner, the vibration from the stator 40 can be attenuated by the mounting member 70, and the transmission of vibration from the stator 40 to the motor housing 30 can be suppressed. That is, as shown by an arrow α in FIG. 3, the vibration of the stator 40 is transmitted to the partition wall 32 of the motor housing 30 via the mounting arm 87, the annular wall portion 83, the connecting portion 74, and the flange portion 71 that constitute the mounting member 70. That is, the vibration can be attenuated via the mounting arm 87, the annular wall portion 83, the connecting portion 74, and the flange portion 71, and the transmission of vibration from the stator 40 to the motor housing 30 can be suppressed.

[0019] 5, an outer diameter D1 of a connecting portion 74 connecting the motor holding portion 73 and the flange portion 71 is set to be smaller than an outer diameter D2 of the motor holding portion 73. This allows the rigidity of the connecting portion 74 to be set lower than the rigidity of the motor holding portion 73, and vibrations directed from the motor holding portion 73 to the flange portion 71 can be effectively damped in the connecting portion 74. Moreover, since both the stator 40 and the rotor 50 are attached to the motor holding portion 73, relative displacement between the stator 40 and the rotor 50 can be suppressed, and interference between the stator 40 and the rotor 50 can be avoided.

[0020] Here, Fig. 7A and Fig. 7B are diagrams showing an example of the deformation state of the mounting member 70. In Fig. 7A and Fig. 7B, the deformation state of the mounting member 70 is exaggerated in order to make it easier to understand the deformation state of the mounting member 70. As shown in Fig. 7A and Fig. 7B, the vibration from the stator 40 toward the motor housing 30 is attenuated by deforming the low-rigidity connecting portion 74. That is, the motor holding portion 73 of the mounting member 70 that holds the stator 40 vibrates approximately around the connecting portion 74 as shown by the arrow β. At this time, since the motor holding portion 73 holds not only the stator 40 but also the rotor 50, the stator 40 and the rotor 50 can be vibrated together, and interference between the stator 40 and the rotor 50 can be avoided. In addition, since interference between the stator 40 and the rotor 50 can be avoided, the air gap between the stator 40 and the rotor 50 can be narrowed.

[0021] Moreover, rotor support portion 80 supporting rotor 50 supports bearing 57 by support shaft portion 82 arranged inside rotor shaft 53. This makes it possible to reduce the size of mounting member 70 including rotor support portion 80, and to reduce the manufacturing cost of mounting member 70. That is, as shown by arrow X1 in FIG. 3, if a part is extended from mounting member 70 toward one end 54 of rotor shaft 53 and a bearing attached to one end 54 of rotor shaft 53 is supported by this part, mounting member 70 will become larger and more expensive. However, in motor generator MG2 of the present disclosure, by using support shaft portion 82 arranged inside rotor shaft 53, mounting member 70 can be reduced in size and cost.

[0022] 3, the center line C1 of the screw hole 72 formed in the flange portion 71 is located closer to the rotation center Cr of the rotor 50 than the center line C2 of the screw hole 88 formed in the stator mounting portion 81. This allows the vibration transmission portion from the mounting member 70 to the motor housing 30 to be separated from the outer housing main body 31, which is the main noise generating portion. In other words, instead of fixing the mounting member 70 to the housing main body 31, the mounting member 70 is fixed to the partition wall 32 of the motor housing 30. This allows vibration to be transmitted to the partition wall 32 at a portion separated from the housing main body 31, thereby suppressing noise generation from the housing main body 31.

[0023] 3, the connecting portion 74 that connects the motor holding portion 73 and the flange portion 71 is located closer to the rotation center Cr of the rotor 50 than the center line C1 of the screw hole 72 formed in the flange portion 71. By arranging the connecting portion 74 closer to the rotation center Cr in this manner, the vibration transmission path from the stator 40 to the motor housing 30 can be lengthened, and the transmission of vibration from the stator 40 to the motor housing 30 can be suppressed. In other words, as shown by the arrow α, the vibration transmission path can be set to turn back at the connecting portion 74, and the vibration transmission path from the stator 40 to the motor housing 30 can be set to be long.

[0024] <Intermediate connecting shaft> 3, the rotor shaft 53 of the motor generator MG2 and the sun gear 28s of the planetary gear train 28 are connected to each other via an intermediate connecting shaft 92. A large diameter portion 93 of the intermediate connecting shaft 92 is formed with spline teeth 94 that mesh with the spline teeth 55 of the rotor shaft 53, and a small diameter portion 95 of the intermediate connecting shaft 92 is formed with spline teeth 96 that mesh with the spline teeth 29 of the sun gear 28s. In this way, the rotor shaft 53 and the intermediate connecting shaft 92 are connected to each other via the spline teeth 55, 94, and the intermediate connecting shaft 92 and the sun gear 28s are connected to each other via the spline teeth 29, 96. In other words, a predetermined backlash is set between the rotor shaft 53 and the intermediate connecting shaft 92, and a predetermined backlash is set between the intermediate connecting shaft 92 and the sun gear 28s.

[0025] In this way, by providing backlash at the connection portion between the rotor shaft 53, the intermediate connecting shaft 92, and the sun gear 28s, it is possible to tolerate minute vibrations of the motor assembly 34 due to vibrations of the stator 40. That is, as shown in Figs. 7A and 7B, a backlash γ is provided between the rotor shaft 53 and the intermediate connecting shaft 92, so that minute vibrations of the motor assembly 34 can be tolerated without being restricted by the intermediate connecting shaft 92. In this way, since minute vibrations of the motor assembly 34 are permitted, the vibrations can be appropriately damped by the mounting member 70. Note that, in order to prevent minute vibrations of the motor assembly 34 from being restricted by the sun gear 28s, a backlash is also provided between the intermediate connecting shaft 92 and the sun gear 28s, but depending on the magnitude of vibrations that may occur in the motor assembly 34, the backlash between the intermediate connecting shaft 92 and the sun gear 28s may be eliminated.

[0026] <Second embodiment> In the example shown in Fig. 3, the inner ring 57i of the bearing 57 and the outer ring 60o of the bearing 60 are supported by the mounting member 70, but this is not limited thereto, and the inner ring 57i of the bearing 57 and the inner ring 60i of the bearing 60 may be supported by the mounting member 70. Fig. 8 is a cross-sectional view showing a motor-generator MG3 according to another embodiment of the present disclosure. In Fig. 8, parts and members similar to those shown in Fig. 3 are denoted by the same reference numerals and description thereof will be omitted.

[0027] 8, rotor 100 constituting motor generator (electric motor) MG3 has a rotor shaft (hollow shaft) 101 with a hollow structure fixed to the center of rotor core 51. An outer ring 57o of bearing 57 is attached to an inner circumferential surface 103 formed at one end 102 of rotor shaft 101, and an outer ring 106o of bearing 106 is attached to an inner circumferential surface 105 formed at the other end 104 of rotor shaft 101.

[0028] The motor holding portion 111 of the mounting member 110 has a rotor support portion 112 that rotatably supports the rotor 100, and a stator mounting portion 113 that is attached to the stator 40. The rotor support portion 112 has a support shaft portion 114 that is disposed inside the rotor shaft 101, and the stator mounting portion 113 has a plurality of mounting arms 115 that extend radially outward from the support shaft portion 114. The support shaft portion 114 is formed with an outer circumferential surface 116 for mounting the inner ring 57i of the bearing 57, and the support shaft portion 114 is formed with an outer circumferential surface 117 for mounting the inner ring 106i of the bearing 106.

[0029] In this way, even with a structure in which the inner rings 57i, 106i of the bearings 57, 106 are supported by the mounting member 110, it is possible to make it function similarly to the above-mentioned mounting member 70. In other words, by providing the mounting member 110 between the motor housing 30 and the stator 40, the vibration from the stator 40 can be attenuated by the mounting member 110, and the transmission of vibration from the stator 40 to the motor housing 30 can be suppressed. Moreover, the rotor support portion 112 that supports the rotor 100 supports the bearing 57 by the support shaft portion 114 that is disposed inside the rotor shaft 101. This makes it possible to achieve a reduction in the size of the mounting member 110 that includes the rotor support portion 112, and thus reduces the manufacturing cost of the mounting member 110.

[0030] <Other embodiments> The present disclosure is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the gist of the present disclosure. In the illustrated example, the mounting member 70 is incorporated into the motor generator MG2, but the present disclosure is not limited to this, and the mounting member 70 may be incorporated into the motor generator MG1. In the illustrated example, the mounting member 70 is incorporated into the motor generator MG2 constituting the power unit 12, but the present disclosure is not limited to this, and the mounting members 70, 110 may be incorporated into an electric motor constituting an electric axle of an electric vehicle or the like. The electric motor into which the mounting members 70, 110 are incorporated is not limited to an electric motor mounted on a hybrid vehicle, an electric vehicle, or the like, and may be an electric motor used in equipment other than a vehicle.

[0031] 6, the stator mounting portion 81 is formed by four mounting arms 87, but is not limited thereto, and the stator mounting portion 81 may be formed by five or more mounting arms 87, or may be formed by three or less mounting arms 87. Also, as indicated by dashed line X2 in Fig. 6, the stator mounting portion 81 may be formed in a disk shape that spreads outward in the radial direction from the annular wall portion 83 of the rotor support portion 80. Also, as the material of the mounting members 70, 110, a metal material such as aluminum alloy or cast iron, or a resin material such as engineering plastic may be used. [Explanation of symbols]

[0032] 30...motor housing (housing), 40...stator, 50...rotor, 53...rotor shaft (hollow shaft), 54...one end (first end), 55...spline teeth, 57...bearing (first bearing), 57o...outer ring, 58...other end (second end), 60...bearing (second bearing), 60i...inner ring, 70...mounting member, 71...flange portion (housing mounting portion), 72...screw hole (first bolt hole, bolt hole), 73...motor holding portion, 74...connecting portion, 8 0...rotor support portion, 81...stator mounting portion, 82...support shaft portion, 88...screw hole (second bolt hole), 92...intermediate connecting shaft (output shaft), 94...spline teeth, 100...rotor, 101...rotor shaft (hollow shaft), 110...mounting member, 111...motor holding portion, 112...rotor support portion, 113...stator mounting portion, 114...support shaft portion, MG1, MG2, MG3...motor generator (electric motor), C1, C2...center line, Cr...center of rotation

Claims

1. Housing and a stator accommodated in the housing; a rotor disposed inside the stator and having a hollow shaft supported by bearings; an attachment member including a motor holding portion that holds the stator and the rotor, a housing attachment portion that is attached to the housing, and a connecting portion that connects the motor holding portion and the housing attachment portion to each other; having The motor holding portion is a rotor support portion including a support shaft portion disposed inside the hollow shaft and supporting an inner ring of the bearing by the support shaft portion; a stator attachment portion extending radially outward from the rotor support portion and attached to the stator; Equipped with Electric motor.

2. 2. The electric motor according to claim 1, a first bolt hole for inserting a mounting bolt is formed in the housing mounting portion; A second bolt hole into which a mounting bolt is inserted is formed in the stator mounting portion, A center line of the first bolt hole is located closer to the rotation center of the rotor than a center line of the second bolt hole. Electric motor.

3. 2. The electric motor according to claim 1, The housing mounting portion is formed with a bolt hole for inserting a mounting bolt, The connecting portion is located closer to the rotation center of the rotor than the center line of the bolt hole. Electric motor.

4. 2. The electric motor according to claim 1, the bearing is a first bearing having an outer ring attached to a first end of the hollow shaft, In addition to the bearing, a second bearing is provided with an inner ring attached to a second end of the hollow shaft. Electric motor.

5. 2. The electric motor according to claim 1, An output shaft is connected to the hollow shaft via spline teeth. Electric motor.

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