Motor unit

Abstract

One embodiment of the motor unit of the present invention includes: a motor having a rotor, a hollow shaft, and a stator, wherein the rotor rotates around the motor axis, the hollow shaft is connected to the rotor and rotates around the motor axis, and the stator and the rotor are radially opposite; and a gear unit having a plurality of gears and an output shaft, wherein the output shaft is connected to the hollow shaft via the gears and rotates around the motor axis. The hollow shaft allows at least a portion of the output shaft to pass through the inside. An internal bearing is arranged between the inner circumference of the hollow shaft and the outer circumference of the output shaft.

Description

Technical Field

[0001] The invention relates to a motor unit.

[0002] This application claims priority based on Japanese Patent Application No. 2020-044473 filed on March 13, 2020, the contents of which are incorporated herein by reference. Background Art

[0003] In recent years, the development of drive devices installed in electric vehicles has been actively carried out. Patent Document 1 describes a motor-type power device (motor unit) which is miniaturized by passing an output shaft through the inside of a hollow rotor shaft.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-121552 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] In the conventional structure, the output shaft is supported at the portions exposed from both axial sides of the hollow rotor shaft. Therefore, the supporting points at both ends of the output shaft are separated, and the output shaft is prone to bending. Therefore, in order to prevent the output shaft from interfering with the rotor shaft, the outer diameter of the output shaft needs to be increased, resulting in a problem of enlarging the motor unit in the radial direction.

[0009] One object of one embodiment of the present invention is to provide a motor unit capable of suppressing deflection of an output shaft.

[0010] Technical solutions adopted to solve technical problems

[0011] One aspect of the motor unit of the present invention includes: a motor having a rotor, a hollow shaft, and a stator, wherein the rotor rotates around a motor axis, the hollow shaft is connected to the rotor and rotates around the motor axis, and the stator and the rotor are radially opposite; and a gear unit having a plurality of gears and an output shaft, wherein the output shaft is connected to the hollow shaft via the gears and rotates around the motor axis. The hollow shaft allows at least a portion of the output shaft to pass through the inside. An internal bearing is arranged between the inner circumference of the hollow shaft and the outer circumference of the output shaft.

[0012] Effects of the Invention

[0013] According to one aspect of the present invention, it is possible to provide a motor unit capable of suppressing deflection of an output shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a conceptual diagram of the motor unit according to the first embodiment.

[0015] Figure 2 This is a conceptual diagram of a motor unit according to the second embodiment. DETAILED DESCRIPTION

[0016] Hereinafter, a motor unit 10 according to an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, the scope of the present invention is not limited to the following embodiments, but can be arbitrarily changed within the scope of the technical concept of the present invention. In addition, in the following drawings, in order to facilitate the understanding of each structure, the scale, number, etc. of each structure may be different from the actual structure.

[0017] <First embodiment>

[0018] Figure 1 This is a conceptual diagram of the motor unit 10 according to the first embodiment.

[0019] In the following description, the direction of gravity is defined based on the positional relationship when the motor unit 10 is installed in a vehicle located on a horizontal road surface. In addition, the Y-axis is shown in the accompanying drawings. The Y-axis direction is a direction parallel to the motor axis J1 of the motor 1. In addition, the Y-axis direction represents the width direction (left-right direction) of the vehicle. In the following description, unless otherwise specified, the direction parallel to the motor axis J1 of the motor 1 (Y-axis direction) is referred to as "axial direction". In addition, the direction axially and on the +Y side is referred to as one axial side, and the -Y side is referred to as the other axial side. In addition, the radial direction centered on the motor axis J1 is referred to as "radial direction", and the circumferential direction centered on the motor axis J1, that is, the direction of the axis around the motor axis J1, is referred to as "circumferential direction".

[0020] In addition, the motor axis J1 and the auxiliary shaft axis J3 described later are virtual axes that do not actually exist.

[0021] The motor unit 10 is mounted on the vehicle and moves the vehicle forward or backward by rotating the wheels H. The motor unit 10 is mounted on an electric vehicle (EV), for example. In addition, the motor unit 10 can be mounted on any vehicle that uses a motor as a power source, such as a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHV).

[0022] like Figure 1 As shown, the motor unit 10 includes a motor 1, a gear part 5, an inverter 8, a housing 6 for accommodating the motor 1, the gear part 5 and the inverter 8, a shaft retaining part 80 for retaining the shaft in the housing 6, a stator retaining frame 40 for retaining the stator 35 of the motor 1 in the housing 6, and oil O.

[0023] (shell)

[0024] The housing 6 is made of, for example, aluminum die casting. The housing 6 includes: a housing body 60; a blocking member 67 located on one axial side (+Y side) of the housing body 60; an inverter cover 68 located on the upper side of the housing body 60; and a bottom cover member 69 located on the lower side of the housing body 60. The housing 6 is formed by fastening the housing body 60, the blocking member 67, the inverter cover 68, and the bottom cover member 69 to each other.

[0025] A driver housing space 61, an inverter housing space 62, and an oil storage space 63 are provided in the housing body 60. The inverter housing space 62 is arranged above the driver housing space 61, and the oil storage space 63 is arranged below.

[0026] The drive body storage space 61 is a space that is connected to each other and stores the motor 1, the gear part 5, the shaft holding part 80, the stator holder 40, and the oil O. In addition, the inverter storage space 62 is a space that stores the inverter 8. The oil storage space 63 is a space that stores the oil O that circulates in the drive body storage space 61. In this way, the housing body 60 stores the motor 1, the gear part 5, the shaft holding part 80, the stator holder 40, the inverter 8, and the oil O in each space.

[0027] A communication hole 65 connected to the oil storage space 63 is provided on the lower wall surface of the driving body storage space 61. The oil O in the lower region of the driving body storage space 61 flows into the oil storage space 63 from the communication hole 65. The oil O is stored in the lower region of the driving body storage space 61 and the oil storage space 63.

[0028] The oil O circulates in the oil passage 90 provided in the housing 6. The oil O functions as lubricating oil for lubricating the gear portion 5, and also functions as cooling oil for cooling the motor 1. That is, the oil O is contained in the housing 6 and lubricates the gear portion 5. As the oil O, it is preferable to use the same oil as the automatic transmission lubricating oil (ATF: Automatic Transmission Fluid) having a low viscosity.

[0029] A portion of the gear ring 51 described later of the gear unit 5 is immersed in the oil O accumulated in the lower area of ​​the driver housing space 61. The oil O is lifted by the action of the gear ring 51 and diffuses into the driver housing space 61. The oil O diffused into the driver housing space 61 is supplied to each gear of the gear unit 5 in the driver housing space 61 and spreads over the tooth surfaces of the gears. The oil O supplied to the gear unit 5 and used for lubrication drips and is recovered in the lower area of ​​the driver housing space 61.

[0030] The housing body 60 has a first opening 61a that exposes the driver housing space 61 on one side (+Y side) in the axial direction, a second opening 62a that exposes the inverter housing space 62 on the upper side, and a third opening 63a that exposes the oil storage space 63 on the lower side. The first opening 61a is covered by a blocking member 67. The second opening 62a is covered by an inverter cover 68. The third opening 63a is covered by a bottom cover member 69.

[0031] The housing body 60 has a cylindrical portion 60a centered on the motor axis J1 and a bottom portion 60b covering the other axial side of the cylindrical portion 60a. The cylindrical portion 60a surrounds the motor 1 from the radially outer side. The bottom portion 60b is located on the other axial side (-Y side) of the motor 1. The bottom portion 60b has a bearing retaining portion 60ba that retains a ball bearing (second external bearing) 71. The bottom portion 60b supports the output shaft 55 via the ball bearing 71. In addition, the bottom portion 60b supports the oil pump 96.

[0032] The closing member 67 covers the first opening 61a and supports the counter shaft 13 described later via a ball bearing 79. The closing member 67 rotatably supports the gear housing 52 and the ring gear 51 described later via a tapered roller bearing 77.

[0033] (Oil circuit)

[0034] The oil passage 90 is a path of the oil O that circulates the oil O in the housing 6. The oil passage 90 is provided in the housing 6. The oil passage 90 is provided with an oil pump 96. The oil passage 90 includes a first flow passage 91 that guides the oil O from the oil storage space 63 to the oil pump 96, and a second flow passage 92 that extends from the oil pump 96 toward the upper side of the motor 1 and supplies the oil O to the motor 1. The oil O reaches the oil pump 96 from the oil storage space 63 via the first flow passage 91, and is supplied from the oil pump 96 to the motor 1 via the second flow passage 92. Further, the oil O drips from the motor 1 and returns to the oil storage space 63.

[0035] The first flow path 91 and the second flow path 92 are provided inside the wall surface of the housing body 60. The first flow path 91 is connected to the oil pump 96 from the oil storage space 63. On the other hand, the second flow path 92 extends upward from the oil pump 96, branches, and opens on the upper side of the stator 35.

[0036] The oil pump 96 is located on the other axial side (-Y side) of the motor 1. The oil pump 96 is a mechanical pump connected to the output shaft 55 and driven by the rotation of the output shaft 55. The oil pump 96 sucks up the oil O from the oil storage space 63 and pumps it into the oil passage 90 under pressure.

[0037] (Inverter)

[0038] The inverter 8 is arranged in the inverter storage space 62. The inverter 8 is fixed to the inverter cover 68. The inverter 8 is connected to the stator 35 of the motor 1 via the bus bar 9. The inverter 8 converts the direct current into the alternating current and supplies it to the motor 1. That is, the inverter 8 controls the current supplied to the motor 1.

[0039] (motor)

[0040] The motor 1 is a motor generator having both the function of an electric motor and the function of a generator. The motor 1 mainly functions as an electric motor to drive the vehicle, and functions as a generator during regeneration. The motor 1 of the present embodiment is a three-phase AC motor.

[0041] The motor 1 is connected to an inverter 8 via a bus bar 9. The inverter 8 converts a direct current supplied from a battery (not shown) into an alternating current and supplies the alternating current to the motor 1. By controlling the inverter 8, each rotation speed of the motor 1 is controlled.

[0042] The motor 1 includes a rotor 31, a stator 35 located radially outside the rotor 31, a hollow shaft 15 located radially inside the rotor 31, a first inner bearing 2, and a second inner bearing 4. The rotor 31 rotates around the motor axis J1. The stator 35 is annular. The stator 35 and the rotor 31 are opposite in the radial direction.

[0043] The rotor 31 has a rotor core 31a and a rotor magnet (not shown) held by the rotor core 31a. The rotor 31 rotates around the motor axis J1. The torque of the rotor 31 is transmitted to the gear part 5 via the hollow shaft 15. A plurality of rotor magnets are fixed to the rotor core 31a. The plurality of rotor magnets are arranged circumferentially in such a way that the magnetic poles are alternated.

[0044] The stator 35 includes: an annular stator core 35a; a coil 35b wound around the stator core 35a; and an insulator (not shown) interposed between the stator core 35a and the coil 35b. The stator core 35a includes a plurality of pole teeth protruding radially inward of the motor axis J1. Coil wires are wound around the pole teeth. The coil wires wound around the pole teeth constitute the coil 35b.

[0045] The hollow shaft 15 extends along the motor axis J1 extending in the width direction of the vehicle. The hollow shaft 15 is connected to the rotor 31. The hollow shaft 15 rotates around the motor axis J1. The hollow shaft 15 has a motor shaft 32 and an input shaft 11 connected to each other in the axial direction. That is, the motor shaft 32 and the input shaft 11 are respectively a part of the hollow shaft 15. As described below, a first inner bearing 2 and a second inner bearing 4 are arranged inside the hollow shaft 15.

[0046] The motor shaft 32 is a hollow shaft that is open to both axial sides of the motor axis J1. That is, the motor shaft 32 has a hollow portion 32h that is open to both axial sides. The motor shaft 32 has a first end portion 32A that is located on one axial side (+Y side) and a second end portion 32B that is located on the other axial side (-Y side).

[0047] The first end 32A of the motor shaft 32 is rotatably supported by the ball bearing 73. The second end 32B of the motor shaft 32 is rotatably supported by the ball bearing 72. A female spline 32b is provided at the opening of the hollow portion 32h of the first end 32A. The motor shaft 32 is connected to the input shaft 11 of the gear unit 5 at the female spline 32b of the first end 32A.

[0048] The input shaft 11 is a hollow shaft that is open on both axial sides of the motor axis J1. That is, the input shaft 11 has a hollow portion 11h that is open on both axial sides.

[0049] The input shaft 11 has a first end portion 11A located at one axial side (+Y side) and a second end portion 11B located at the other axial side (-Y side). The input shaft 11 is rotatably supported by a ball bearing (first external bearing) 74 between the first end portion 11A and the second end portion 11B.

[0050] A male spline 11a is provided on the outer peripheral surface of the second end portion 11B of the input shaft 11. The male spline 11a is engaged with the female spline 32b of the motor shaft 32. Thus, the first end portion 32A of the motor shaft 32 and the second end portion 11B of the input shaft 11 are connected to each other. That is, the input shaft 11 is connected to the end portion of the motor shaft 32 on the gear portion 5 side. In addition, the input shaft 11 rotates around the motor axis J1 together with the motor shaft 32. In addition, the hollow portion 32h of the motor shaft 32 and the hollow portion 11h of the input shaft 11 are connected to each other. The input shaft 11 is rotated by the rotation of the motor 1 being transmitted.

[0051] (Gear Department)

[0052] The gear unit 5 is connected to one axial side (+Y side) of the motor 1. The gear unit 5 transmits the power of the motor 1 and outputs it from the output shaft 55. The gear unit 5 has a plurality of mechanisms built therein for transmitting power between the driving source and the driven device.

[0053] The gear portion 5 includes an input gear 21 , a counter shaft 13 , a counter gear 23 , a drive gear 24 , a ring gear 51 , an output shaft 55 , and a differential device 50 .

[0054] Each gear and each shaft of the gear unit 5 can rotate around either the motor axis J1 or the secondary shaft axis J3. In the present embodiment, the motor axis J1 and the secondary shaft axis J3 extend parallel to each other. In addition, the motor axis J1 and the secondary shaft axis J3 are parallel to the width direction of the vehicle. In the following description, the axial direction refers to the axial direction of the motor axis J1. That is, the axial direction in this specification refers to the direction parallel to the motor axis J1, that is, the width direction of the vehicle.

[0055] The input gear 21 is disposed on the outer circumferential surface of the first end portion 11A of the input shaft 11. The input gear 21 meshes with the countershaft gear 23. The input gear 21 rotates around the motor axis J1 together with the input shaft 11. In the present embodiment, the input gear 21 and the input shaft 11 are a single component. However, the input gear 21 may also be a different component mounted on the outer circumferential surface of the input shaft 11.

[0056] The secondary shaft 13 extends along the secondary shaft axis J3. The secondary shaft 13 rotates around the secondary shaft axis J3. The secondary shaft 13 has a first end 13A located on one axial side (+Y side) and a second end 13B located on the other axial side (-Y side).

[0057] The first end 13A of the countershaft 13 is rotatably supported by a ball bearing 79. The second end 13B of the countershaft 13 is rotatably supported by a ball bearing 78. A countershaft gear 23 and a drive gear 24 are provided on the outer peripheral surface of the countershaft 13 and between the first end 13A and the second end 13B in the axial direction. In the present embodiment, the drive gear 24 is located on one axial side (+Y side) of the countershaft gear.

[0058] The counter gear 23 rotates together with the counter shaft 13 about the counter shaft axis J3 . The counter gear 23 meshes with the input gear 21 .

[0059] The drive gear 24 rotates around the counter shaft axis J3 together with the counter shaft 13 and the counter gear 23 .

[0060] The ring gear 51 is a gear centered on the motor axis J1. The ring gear 51 is fixed to the differential device 50. The ring gear 51 rotates around the motor axis J1. The ring gear 51 meshes with the drive gear 24. The ring gear 51 transmits the power of the motor 1 transmitted via the drive gear 24 to the differential device 50.

[0061] The differential device 50 is arranged with the motor axis J1 as the center. That is, the differential device 50 is arranged on the same axis as the motor 1. The differential device 50 is a device for transmitting the torque output from the motor 1 to the wheels H of the vehicle. The differential device 50 has a function of absorbing the speed difference between the left and right wheels H when the vehicle turns and transmitting the same torque to the output shafts 55 of the left and right wheels.

[0062] The differential device 50 includes a gear housing 52 fixed to the ring gear 51, a pair of pinion gears 53a, a pinion shaft 53b, and a pair of side gears 54. The gear housing 52 rotates together with the ring gear 51 about the motor axis J1.

[0063] The gear housing 52 accommodates a pair of pinion gears 53a, a pinion gear shaft 53b, and a pair of side gears 54. The pair of pinion gears 53a are bevel gears disposed on the same axis and facing each other. The pair of pinion gears 53a are supported by the pinion gear shaft 53b. The pair of side gears 54 are bevel gears meshing with the pair of pinion gears 53a at right angles. The pair of side gears 54 are fixed to the output shaft 55, respectively.

[0064] The gear housing 52 is rotatably supported from both sides in the axial direction by the tapered roller bearings 76 and 77. That is, the ring gear 51 is supported by the tapered roller bearings 76 and 77 via the gear housing 52.

[0065] The output shaft 55 extends along the motor axis J1. The output shaft 55 rotates around the motor axis J1. A pair of output shafts 55 arranged in the axial direction are provided in the motor unit 10. The pair of output shafts 55 are connected to the side gear 54 of the differential device 50 at the end of one side respectively. That is, the output shaft 55 is connected to the ring gear 51 via the differential device 50. The power of the motor 1 is transmitted to the output shaft 55 via each gear. In addition, the pair of output shafts 55 protrude to the outside of the housing 6 at the end of the other side respectively. The wheel H is installed at the other end of the output shaft 55. The output shaft 55 outputs power to the outside (outputs to the road surface via the wheel H).

[0066] In the present embodiment, the output shaft 55 is disposed coaxially with the hollow shaft 15. One of the pair of output shafts 55 disposed on the other axial side (-Y side) passes through the interior of the hollow shaft 15 (ie, the hollow portions 32h, 11h).

[0067] According to the motor unit 10 of this embodiment, a portion of the output shaft 55 is arranged inside the hollow shaft 15, thereby allowing the motor 1 and the differential device 50 to be arranged coaxially when viewed in the axial direction, and the radial dimension of the motor axis J1 of the motor unit 10 can be miniaturized.

[0068] The gear unit 5 constitutes a power transmission path from the motor 1 to the output shaft 55. The gear unit 5 has a plurality of gears (an input gear 21, a countershaft gear 23, a drive gear 24, a ring gear 51, a pinion gear 53a, and a side gear 54). The gear unit 5 transmits power from the hollow shaft 15 to the output shaft 55 through the plurality of gears. The power of the motor 1 is first transmitted from the motor shaft 32 to the input shaft 11, and then transmitted from the input gear 21 to the countershaft gear 23. The countershaft gear 23 is arranged on the same axis as the drive gear 24 and rotates together with the drive gear 24. The power of the motor 1 is transmitted from the drive gear 24 to the ring gear 51, and is transmitted to the output shaft 55 via the differential device 50.

[0069] (Stator cage)

[0070] The stator holder 40 includes a cylindrical portion 41 surrounding the stator 35 from the radially outer side, and a bottom plate portion 42 extending radially inward from an end portion of the cylindrical portion 41 on the other axial side (−Y side).

[0071] The outer peripheral surface of the cylindrical portion 41 is embedded in the inner side surface of the cylindrical portion 60a of the housing body 60. In addition, the stator 35 is embedded in the inner side surface of the cylindrical portion 41. In addition, an embedding portion 41p is provided on the inner peripheral surface of the cylindrical portion 41. The embedding portion 41p is provided at the opening on one axial side (+Y side) of the cylindrical portion 41. The shaft holding portion 80 is embedded in the embedding portion 41p. That is, the stator holder 40 is fixed to the housing body 60, and supports the stator 35 and the shaft holding portion 80.

[0072] A recess 44 is provided on the outer peripheral surface of the cylindrical portion 41. The recess 44 extends over the entire circumference around the motor axis J1. The recess 44 opens radially outward. The opening of the recess 44 is covered by the inner side surface of the housing body 60. The recess 44 functions as a passage portion for the refrigerant W to flow. The refrigerant W flows in the recess 44 along the circumferential direction. The refrigerant W cools the stator 35 via the stator holder 40. The refrigerant W is cooled by passing through a heat exchanger (not shown).

[0073] The bottom plate portion 42 is located on the other axial side (-Y side) relative to the motor 1. The bottom plate portion 42 is in the shape of a plate that is orthogonal to the motor axis J1. A through hole 42a is provided in the center of the bottom plate portion 42. The through hole 42a penetrates the bottom plate portion 42 in the plate thickness direction. The bottom plate portion 42 has a bearing retaining portion 43 that protrudes from the edge of the through hole 42a to one axial side (+Y side). The bottom plate portion 42 retains the ball bearing 72. Therefore, the bottom plate portion 42 can support the motor shaft 32 via the ball bearing 72 so that it can rotate.

[0074] (Shaft holding part)

[0075] The shaft holding portion 80 is disposed in the driving body housing space 61. The shaft holding portion 80 is located between the motor 1 and the gear portion 5. The shaft holding portion 80 includes a first retainer 81, a second retainer 86, ball bearings 73, 74, 75, 78, and a tapered roller bearing 76.

[0076] The first retainer 81 is fixed to the stator holder 40 from one axial side (+Y side). In addition, the second retainer 86 is fixed to the first retainer 81 from one axial side (+Y side). The ball bearings 73, 74, 78 are retained by the first retainer 81. In addition, the ball bearing 75 and the tapered roller bearing 76 are retained by the second retainer 86.

[0077] The first retainer 81 is provided with a first insertion hole 82h and a second insertion hole 83h penetrating in the axial direction.

[0078] The first insertion hole 82h is circular with the motor axis J1 as the center when viewed from the axial direction. Ball bearings 73 and 74 are held on the inner side of the first insertion hole 82h. In addition, the first end 32A of the motor shaft 32, the second end 11B of the input shaft 11, and the output shaft 55 are arranged inside the first insertion hole 82h. The first retainer 81 supports the first end 32A of the motor shaft 32 via the ball bearing 73 so that it can rotate. In addition, the first retainer 81 supports the input shaft 11 via the ball bearing 74 so that it can rotate.

[0079] The second insertion hole 83h is circular with the secondary shaft axis J3 as the center when viewed from the axial direction. The ball bearing 78 is held on the inner side of the second insertion hole 83h. In addition, the second end 13B of the secondary shaft 13 is arranged inside the second insertion hole 8h. The first retainer 81 supports the secondary shaft 13 rotatably via the ball bearing 78.

[0080] The second retainer 86 includes a disk portion 88 a and a surrounding tube portion 88 b extending from the outer edge of the disk portion 88 a toward the other side in the axial direction.

[0081] The disc portion 88a is in the shape of a disc with the motor axis J1 as the center. A third insertion hole 88h is provided in the center of the disc portion 88a and penetrates in the axial direction. The third insertion hole 88h is in the shape of a circle with the motor axis J1 as the center when viewed from the axial direction. The output shaft 55 is arranged inside the third insertion hole 88h. The ball bearing 75 and the tapered roller bearing 76 are retained on the inner side surface of the third insertion hole 88h. The second retainer 86 supports the output shaft 55 via the ball bearing 75 so as to be rotatable. The second retainer 86 supports the gear housing 52 via the tapered roller bearing 76 so as to be rotatable.

[0082] The surrounding cylinder portion 88b is in a cylindrical shape with the motor axis J1 as the center. The surrounding cylinder portion 88b is provided with an opening portion 87 that opens on the other axial side (-Y side). The opening portion 87 connects the inside and outside of the surrounding cylinder portion 88b. As a result, the oil O that is scattered into the driving body storage space 61 due to the lifting of the ring gear 51, etc. can reach the surrounding cylinder portion 88b, and the scattered oil O can be supplied to the inside of the surrounding cylinder portion 88b. In addition, the opening portion 87 of the present embodiment exposes the ball bearings 74 and 75 to the driving body storage space 61. Therefore, according to the present embodiment, the oil O can be supplied to the ball bearings 74 and 75 from the opening portion 87, and the lubricity of the ball bearings 74 and 75 can be improved.

[0083] In this embodiment, the opening 87 opens upward. Therefore, the oil O that reaches the inside of the surrounding tube 88b from the opening 87 can be stored inside the surrounding tube 88b. That is, the surrounding tube 88b has the storage space 64 for storing the oil O.

[0084] The surrounding cylindrical portion 88b of the present embodiment surrounds the first end portion 11A of the input shaft 11. Therefore, the hollow portion 11h of the input shaft 11 opens into the reservoir space 64. That is, the hollow portion of the hollow shaft 15 opens toward the reservoir space 64 at one end.

[0085] When the liquid level of the oil O in the storage space 64 rises, a part of the oil O intrudes into the hollow portion 11h, thereby improving the lubricity between the inner peripheral surface of the input shaft 11 and the output shaft 55. In addition, the lubricity of the second inner bearing 4 disposed in the hollow portion 11h of the input shaft 11 is improved. In addition, the oil O is supplied to the male spline 11a and the female spline 32b of the connection portion between the input shaft 11 and the motor shaft 32, thereby suppressing the wear of the connection portion. The oil O is scattered from the connection portion between the male spline 11a and the female spline 32b and supplied to the ball bearing 73 supporting the motor shaft 32, thereby improving the lubricity of the ball bearing 73. In addition, the oil O flows from the hollow portion 11h of the input shaft 11 to the hollow portion 32h of the motor shaft 32. As a result, the lubricity of the first inner bearing 2 disposed in the hollow portion 32h of the motor shaft 32 is improved.

[0086] In the present embodiment, at least a portion of the input gear 21 provided at the first end portion 11A of the input shaft 11 is located in the reservoir space 64. Therefore, the lower end portion of the input gear 21 is immersed in the oil O accumulated in the reservoir space 64. The oil O is lifted up by the movement of the input gear 21, diffuses into the driving body housing space 61, and spreads over the tooth surfaces of each gear.

[0087] In this embodiment, the meshing portion 14 where the input gear 21 meshes with the counter gear 23 is disposed in the opening 87. Therefore, the shaft holding portion 80 can support the shaft on both axial sides of the input gear 21 and transmit power from the input gear 21 to the counter gear 23.

[0088] (Inner bearing)

[0089] The first inner bearing 2 and the second inner bearing 4 are arranged between the inner circumference of the hollow shaft 15 and the outer circumference of the output shaft 55. The first inner bearing 2 and the second inner bearing 4 are needle bearings. That is, the first inner bearing 2 and the second inner bearing 4 respectively have an inner ring, an outer ring, and a needle-shaped rolling element arranged between the inner ring and the outer ring. The output shaft 55 is embedded in the inner ring of the first inner bearing 2 and the second inner bearing 4. In addition, the outer rings of the first inner bearing 2 and the second inner bearing 4 are embedded in the inner circumference of the hollow shaft 15.

[0090] At least a portion of the output shaft 55 passes through the interior of the hollow shaft 15. In the conventional structure, the output shaft 55 is supported at the axially outer side than the two ends of the hollow shaft 15. Therefore, the two ends of the output shaft 55 are supported at a position farther away than the entire length of the hollow shaft 15, and the output shaft 55 is easily bent.

[0091] According to the present embodiment, the first inner bearing 2 and the second inner bearing 4 are arranged between the inner circumferential surface of the hollow shaft 15 and the outer circumferential surface of the output shaft 55. Therefore, the output shaft 55 can be supported inside the hollow shaft 15, and even when the hollow shaft 15 is elongated, the deflection of the output shaft 55 can be suppressed. Furthermore, the hollow shaft 15 is supported by the output shaft 55 from the radial inner side via the inner bearings 2 and 4, and the deflection of the hollow shaft 15 is suppressed.

[0092] According to the present embodiment, the deflection of the output shaft 55 and the hollow shaft 15 is suppressed, so that the interference between the hollow shaft 15 and the output shaft 55 in the radial direction can be suppressed. Therefore, the gap between the outer peripheral surface of the output shaft 55 and the inner peripheral surface of the hollow shaft 15 can be reduced, and the diameter of the hollow shaft 15 can be reduced. As a result, the radial dimension of the motor unit 10 as a whole can be miniaturized.

[0093] According to the present embodiment, the output shaft 55 is rotatably supported by the ball bearings (second outer bearings) 71, 75. The inner bearings 2, 4 are axially arranged between the ball bearings 71, 75. Therefore, the inner bearings 2, 4 can effectively suppress the deflection of the output shaft 55 generated between the ball bearings 71, 75.

[0094] According to the present embodiment, the inner bearings 2 and 4 are needle bearings with reduced radial dimensions. Therefore, the diameter of the hollow shaft 15 can be reduced, and the radial dimension of the entire motor unit 10 can be reduced.

[0095] The output shaft 55 and the hollow shaft 15 rotate in the same direction with the motor axis J1 as the center. Therefore, the inner ring and the outer ring of the inner bearings 2 and 4 rotate relative to each other according to the reduction ratio of the gear unit 5. The rotation speed of the inner bearings 2 and 4 is lower than the rotation speed of the ball bearings 71 and 75 supporting both ends of the output shaft 55. Therefore, the inner bearings 2 and 4 can support the output shaft 55 while suppressing the amount of wear compared with the ball bearings 71 and 75 supporting both ends of the output shaft 55.

[0096] According to this embodiment, two inner bearings 2 and 4 are arranged axially between the inner circumference of the hollow shaft 15 and the outer circumference of the output shaft 55. Therefore, even if the overall length of the hollow shaft 15 is increased, the bending of the hollow shaft 15 and the output shaft 55 can be effectively suppressed.

[0097] According to the present embodiment, the first inner bearing 2 is arranged in the hollow portion 32h of the motor shaft 32, and the second inner bearing 4 is arranged in the hollow portion 11h of the input shaft 11. That is, the hollow shaft 15 includes: the motor shaft 32 that accommodates the first inner bearing 2; and the input shaft 11 that accommodates the second inner bearing 4. The motor shaft 32 and the input shaft 11 are separable from each other. Therefore, in the assembly process, the two inner bearings 2 and 4 can be easily accommodated inside the hollow shaft 15.

[0098] According to the present embodiment, the rotor 31 is fixed to the outer peripheral surface of the motor shaft 32. The motor shaft 32 is easily bent due to the weight of the rotor 31. According to the present embodiment, the first inner bearing 2 is arranged in the hollow portion 32h of the motor shaft 32, so the bending of the motor shaft 32 can be suppressed. In addition, the axial position of the first inner bearing 2 in the present embodiment overlaps with the axial position of the rotor 31. Therefore, the bending of the motor shaft 32 caused by the weight of the rotor 31 can be effectively suppressed.

[0099] In the hollow shaft 15, the rotation around the motor axis J1 is easily stabilized in the area supported by the inner bearings 2 and 4. According to the present embodiment, the axial position of the second inner bearing 4 overlaps with the axial position of the input gear 21. Therefore, the input gear 21 can stabilize the rotation around the motor axis J1.

[0100] According to the present embodiment, the input shaft 11 is rotatably supported by the ball bearing (first outer bearing) 74 that holds a portion of the outer peripheral surface. That is, the input shaft 11 is cantilever supported by the ball bearing 74. In addition, the ball bearing 74 is arranged at a position different from the second inner bearing 4 in the axial direction. Therefore, the input shaft 11 is supported by the ball bearing 74 and the second inner bearing 4 at both ends of the input shaft 11 in a double-point support structure. As a result, the ball bearing 74 and the second inner bearing 4 can stably support the input shaft 11.

[0101] <Second embodiment>

[0102] Figure 2 1 is a conceptual diagram of a motor unit 110 according to a second embodiment. The motor unit 110 according to the present embodiment is different from the motor unit 10 according to the first embodiment mainly in the structure of a gear portion 105 .

[0103] In addition, about the structural elements of the same form as the above-mentioned embodiment, the same symbols are attached|subjected, and the description is abbreviate|omitted.

[0104] The motor unit 110 includes a motor 1 and a gear unit 105. Although not shown in the figure, the motor unit 110 includes an inverter that supplies electric power to the motor 1 and a housing that accommodates the motor 1 and the gear unit 105.

[0105] Similar to the above-described embodiment, the motor 1 includes a rotor 31, a stator 35, a hollow shaft 15, and a first inner bearing 2. The hollow shaft 15 includes a motor shaft 32 and an input shaft 11 connected to each other in the axial direction.

[0106] The gear unit 105 is connected to one axial side (+Y side) of the motor 1. The gear unit 105 transmits the power of the motor 1 and outputs it from the output shaft 155. The gear unit 105 includes a sun gear 121, an internal gear 122, planetary gears 123, a carrier 125, a differential device 150, and an output shaft 155. The sun gear 121, the internal gear 122, the planetary gears 123, and the carrier 125 constitute a planetary gear mechanism.

[0107] The internal gear 122 has an annular shape centered on the motor axis J1. The internal gear 122 meshes with the small diameter portion 123b of the planetary gear 123. The internal gear 122 is fixed to the inner side surface of a housing (not shown), for example.

[0108] The sun gear 121 is provided on the outer peripheral surface of the input shaft 11. The sun gear 121 rotates around the motor axis J1 together with the input shaft 11.

[0109] For example, a plurality of planetary gears 123 are arranged at equal intervals around the motor axis J1. The planetary gear 123 has a large diameter portion 123a, a small diameter portion 123b, and a sub-axis 123c. The large diameter portion 123a and the small diameter portion 123b rotate around the sub-axis 123c. The large diameter portion 123a and the small diameter portion 123b are stepped gears arranged on the same axis. The large diameter portion 123a meshes with the sun gear 121. On the other hand, the small diameter portion 123b meshes with the internal gear 122. The planetary gear 123 revolves in the circumferential direction of the motor axis J1 as the sun gear 121 rotates.

[0110] The carrier 125 is disposed on both axial sides of the planetary gear 123. The carrier 125 supports the planetary gear 123 so as to be able to revolve around the motor axis J1. The carrier 125 rotates around the motor axis J1 as the planetary gear 123 revolves around the motor axis J1. The carrier 125 is connected to the differential device 150.

[0111] The differential device 150 includes a gear housing 152 fixed to the wheel carrier 125, a pair of pinion gears 53a, a pinion gear shaft 53b, and a pair of side gears 54. The gear housing 152 rotates with the wheel carrier 125 around the motor axis J1. The pair of side gears 54 are respectively fixed to the output shaft 155. Therefore, the wheel carrier 125 is connected to the output shaft 155 via the differential device 150.

[0112] The output shaft 155 extends along the motor axis J1. The output shaft 155 rotates around the motor axis J1. A pair of output shafts 155 arranged in the axial direction are provided in the motor unit 110. The pair of output shafts 155 are connected to the side gear 54 of the differential device 150 at one end. The wheel H is mounted on the other end of the output shaft 155.

[0113] The output shaft 155 is coaxially arranged with the hollow shaft 15. The one of the pair of output shafts 155 arranged on the other axial side (-Y side) passes through the interior of the hollow shaft 15. The first internal bearing 2 is arranged between the outer circumference of the output shaft 155 and the inner circumference of the hollow shaft 15.

[0114] According to the present embodiment, by providing a planetary gear mechanism at the gear portion 105, it is possible to further reduce the radial dimension of the motor unit 10 while ensuring a sufficient reduction ratio. In addition, by arranging an internal bearing 2 between the hollow shaft 15 and the output shaft 155, even when the planetary gear mechanism is eccentric, interference between the hollow shaft 15 and the output shaft 155 can be suppressed.

[0115] The embodiments and their variations of the present invention are described above, but the various structures and combinations thereof in the embodiments and their variations are examples, and additions, omissions, substitutions and other changes to the structures can be made without departing from the spirit of the present invention. Moreover, the present invention is not limited to the embodiments.

[0116] Explanation of symbols

[0117] 1 motor; 2, 4 internal bearing; 5, 105 gear part; 6 housing; 10, 110 motor unit; 11 input shaft; 11h, 32h hollow part; 15 hollow shaft; 21 input gear; 31 rotor; 32 motor shaft; 35 stator; 55, 155 output shaft; 64 storage space; 71, 75 ball bearing (second external bearing); 74 ball bearing (first external bearing); 121 sun gear; 122 internal gear; 123 planetary gear; 125 wheel carrier; J1 motor axis; O oil.

Claims

1. A motor unit, comprising: a motor, the motor comprising a rotor, a hollow shaft and a stator, the rotor rotating around the motor axis, the hollow shaft connected to the rotor and rotating around the motor axis, the stator and the rotor being opposite in radial direction; and a gear unit having a plurality of gears and an output shaft, wherein the output shaft is connected to the hollow shaft via the gears and rotates around the motor axis, The hollow shaft allows at least a portion of the output shaft to pass therethrough. An internal bearing is arranged between the inner peripheral surface of the hollow shaft and the outer peripheral surface of the output shaft. The motor has: a motor shaft, the rotor being fixed to an outer peripheral surface of the motor shaft; and an input shaft, the input shaft being a part of the hollow shaft, connected to the end of the motor shaft on the gear portion side, and rotating around the motor axis together with the motor shaft, The gear portion includes an input gear, which is disposed on the outer peripheral surface of the input shaft and meshes with the gear. The axial position of the inner bearing overlaps with the axial position of the input gear.

2. The motor unit according to claim 1, wherein: The inner bearing is a needle roller bearing.

3. The motor unit according to claim 1 or 2, wherein: The motor has a motor shaft, the motor shaft is a part of the hollow shaft, and the rotor is fixed to the outer peripheral surface of the motor shaft. The axial position of the inner bearing overlaps with the axial position of the rotor.

4. The motor unit according to claim 1 or 2, wherein: The input shaft is rotatably supported by a first outer bearing that holds a portion of the outer peripheral surface. The first outer bearing is arranged at a position different from that of the inner bearing in the axial direction.

5. The motor unit according to claim 3, wherein: The input shaft is rotatably supported by a first outer bearing that holds a portion of the outer peripheral surface, and the first outer bearing is arranged at a position different from that of the inner bearing in the axial direction.

6. The motor unit according to any one of claims 1, 2 and 5, wherein: include: a housing for housing the motor and the gear unit; as well as oil, the oil being contained in the housing and lubricating the gear portion, A storage space for storing the oil is provided in the housing. The hollow portion of the hollow shaft opens toward the storage space at one end.

7. The motor unit according to claim 6, wherein: The output shaft is rotatably supported by a second outer bearing. The inner bearing is arranged between the second outer bearings in the axial direction.

8. The motor unit according to claim 3, wherein: include: a housing for housing the motor and the gear unit; as well as oil, the oil being contained in the housing and lubricating the gear portion, A storage space for storing the oil is provided in the housing. The hollow portion of the hollow shaft opens toward the storage space at one end.

9. The motor unit according to claim 8, wherein: The output shaft is rotatably supported by a second outer bearing. The inner bearing is arranged between the second outer bearings in the axial direction.

10. The motor unit according to claim 4, wherein: include: a housing for housing the motor and the gear unit; as well as oil, the oil being contained in the housing and lubricating the gear portion, A storage space for storing the oil is provided in the housing. The hollow portion of the hollow shaft opens toward the storage space at one end.

11. The motor unit according to claim 10, wherein: The output shaft is rotatably supported by a second outer bearing. The inner bearing is arranged between the second outer bearings in the axial direction.

Images