In-wheel motor

Abstract

To downsize an in-wheel motor.SOLUTION: An in-wheel motor includes a fixation member fixed to a vehicle body, a rotary member, a motor, and a planetary gear reduction unit. One of a planetary carrier and a ring gear composes part of the rotary member. Each of planetary gears includes: a small-diameter gear part engaged with the ring gear; and a large-diameter gear part engaged with a sun gear and provided at a position shifted from the small-diameter gear part in a shaft direction. In a diameter direction of a shaft, the large-diameter gear part further projects to an outer peripheral side than the ring gear does. A bearing supporting the rotary member so as to be rotatable around the fixation member is disposed in an outer peripheral region superimposed on the ring gear when seen along the diameter direction, located on an outer peripheral side of the ring gear and also located on an inner peripheral side of an outer peripheral edge of the large-diameter gear part in the diameter direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to an in-wheel motor.

[0002] The in-wheel motor disclosed in Patent Document 1 has a fixed member fixed to the body of a vehicle and a rotating member that rotates together with the tire. The in-wheel motor also has a motor and a planetary gear reduction mechanism. The planetary gear reduction mechanism transmits the rotation of the motor shaft to the rotating member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-194857 A Summary of the Invention [Problem to be solved by the invention]

[0004] The in-wheel motor of Patent Document 1 has a bearing that rotatably supports a rotating member relative to a fixed member. The bearing is disposed on an extension of the central axis of the planetary gear of the planetary gear mechanism. Therefore, this in-wheel motor has a large dimension in the axial direction (i.e., the direction parallel to the central axis of the motor shaft). This specification proposes a technique for miniaturizing the in-wheel motor. [Means for solving the problem]

[0005] The in-wheel motor disclosed in this specification includes a fixed member fixed to a vehicle body, a rotating member rotating together with a tire, a motor having a shaft rotating relative to the fixed member, and a planetary gear reducer transmitting rotation of the shaft to the rotating member. The planetary gear reducer includes a sun gear fixed to the shaft, a ring gear, a plurality of planetary gears arranged between the sun gear and the ring gear, and a planetary carrier rotatably supporting each of the planetary gears. One of the planetary carrier and the ring gear constitutes a part of the rotating member. Each of the planetary gears includes a small diameter gear portion engaging with the ring gear, and a large diameter gear portion that is shifted from the small diameter gear portion in the axial direction of the shaft and engages with the sun gear. In the radial direction of the shaft, the large diameter gear portion protrudes outward from the ring gear. A bearing that rotatably supports the rotating member relative to the fixed member is arranged in an outer peripheral region that overlaps with the ring gear when viewed along the radial direction, is located outer than the ring gear in the radial direction, and is located inner than the outer circumferential end of the large diameter gear portion in the radial direction.

[0006] In this in-wheel motor, bearings are arranged in an outer peripheral area located on the outer periphery of the ring gear. This allows the axial dimension of the in-wheel motor to be reduced. The outer peripheral area is an area that is generated when a large diameter gear portion and a small diameter gear portion are provided in a planetary gear, and by arranging the bearings in this area, the in-wheel motor can be made smaller. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view of the in-wheel motor of the first embodiment. [Diagram 2] FIG. 11 is a cross-sectional view of an in-wheel motor according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An in-wheel motor 10 according to a first embodiment shown in FIG. 1 is mounted on an electric vehicle and drives a wheel of the electric vehicle. The in-wheel motor 10 has a housing 12 and a wheel 90. The housing 12 is a member fixed to the body of the electric vehicle. The wheel 90 has a cylindrical shape, and a tire 92 is attached to its outer circumferential surface. The wheel 90 rotates together with the tire 92. The in-wheel motor 10 rotates the wheel 90 relative to the housing 12.

[0009] The in-wheel motor 10 has a motor 20 and a planetary gear reducer 30. The motor 20 has a stator 22 and a rotor 24. The stator 22 is fixed to the housing 12. The rotor 24 has a rotor core 24a and a rotor shaft 24b. The rotor core 24a is disposed around the stator 22. The rotor core 24a is fixed to the rotor shaft 24b. The rotor shaft 24b is rotatably supported by a bearing 26 provided in the housing 12. When power is supplied to the stator 22, the rotor 24 rotates around the central axis of the rotor shaft 24b.

[0010] The planetary gear reducer 30 has a sun gear 40, a ring gear 50, a plurality of planetary gears 60, and a planetary carrier 70. In the first embodiment, the planetary gear reducer 30 has four planetary gears 60, but the number of planetary gears 60 may be three or less, or five or more.

[0011] The sun gear 40 has a cylindrical shape and has gear teeth on its outer circumferential surface. The sun gear 40 is fixed to the rotor shaft 24b on the outer side of the rotor core 24a in the vehicle width direction. The sun gear 40 rotates together with the rotor shaft 24b.

[0012] The ring gear 50 has a cylindrical shape and has gear teeth on its inner peripheral surface. The rotor shaft 24b is inserted into a central hole of the ring gear 50. The ring gear 50 is disposed concentrically with the rotor shaft 24b. The ring gear 50 is fixed to the housing 12. The ring gear 50 is part of a fixed member that is fixed to the body of the electric vehicle.

[0013] The planetary carrier 70 has a plurality of shafts 70a and a connection portion 70b. Each shaft 70a is arranged in parallel with the rotor shaft 24b. The plurality of shafts 70a are arranged at equal intervals around the rotor shaft 24b. The connection portion 70b connects the plurality of shafts 70a to each other. A through hole is provided at the center of the connection portion 70b, and the rotor shaft 24b is inserted into the through hole. The connection portion 70b is supported by a bearing 72 in a state in which it can rotate relatively to the rotor shaft 24b. That is, the planetary carrier 70 can rotate relatively to the rotor shaft 24b around the rotor shaft 24b. The planetary carrier 70 is fixed to a wheel 90. Therefore, the planetary carrier 70 rotates together with the wheel 90. The planetary carrier 70 is a part of a rotating member that rotates together with a tire 92.

[0014] Each planetary gear 60 has a cylindrical shape. Each planetary gear 60 is disposed between the rotor shaft 24b and the ring gear 50. Each planetary gear 60 is disposed at equal intervals around the rotor shaft 24b. A corresponding shaft 70a of the planetary carrier 70 is inserted into the center hole of each planetary gear 60. Each planetary gear 60 can rotate about the shaft 70a inserted into the center hole. That is, the planetary carrier 70 supports each planetary gear 60 so that it can rotate. As described above, the planetary carrier 70 can rotate about the rotor shaft 24b. When the planetary carrier 70 rotates about the rotor shaft 24b, each planetary gear 60 revolves around the rotor shaft 24b. Each planetary gear 60 has a large diameter gear portion 60a and a small diameter gear portion 60b. The large diameter gear portion 60a and the small diameter gear portion 60b have a cylindrical shape. The diameter of the outer peripheral surface of the large diameter gear portion 60a is larger than the diameter of the outer peripheral surface of the small diameter gear portion 60b. The large diameter gear portion 60a is disposed at a position shifted in the axial direction along the central axis of the rotor shaft 24b with respect to the small diameter gear portion 60b. The large diameter gear portion 60a is disposed on the outer side in the vehicle width direction with respect to the small diameter gear portion 60b. The large diameter gear portion 60a and the small diameter gear portion 60b are fixed to each other. The gear teeth provided on the outer peripheral surface of the large diameter gear portion 60a are engaged with the gear teeth provided on the outer peripheral surface of the sun gear 40. The gear teeth provided on the outer peripheral surface of the small diameter gear portion 60b are engaged with the gear teeth provided on the inner peripheral surface of the ring gear 50. In the radial direction of the rotor shaft 24b, the outer peripheral end 60x of each large diameter gear portion 60a protrudes outward from the ring gear 50.

[0015] A space 82 is provided between the ring gear 50 and the wheel 90 in the radial direction of the rotor shaft 24b. As described above, the outer peripheral end 60x of the large diameter gear portion 60a protrudes more radially outward than the ring gear 50. The large diameter gear portion 60a revolves around the rotor shaft 24b. Therefore, the outer peripheral portion of the wheel 90 is disposed more radially outward than the outer peripheral end 60x of the large diameter gear portion 60a so as not to come into contact with the large diameter gear portion 60a. Therefore, a space 82 exists between the ring gear 50 and the wheel 90. Therefore, the space 82 includes an outer peripheral region 84. The outer peripheral region 84 is a region that overlaps with the ring gear 50 when viewed along the radial direction of the rotor shaft 24b (i.e., a region that exists in the same range as the ring gear 50 in the axial direction of the rotor shaft 24b), and is a region that is located more radially outward than the ring gear 50 and more radially inward than the outer peripheral end 60x of the large diameter gear portion 60a. A bearing 80 is provided in a space 82 including the outer circumferential region 84. The bearing 80 supports a wheel 90 (i.e., a rotating member) rotatably relative to the housing 12 (i.e., a fixed member).

[0016] When the rotor shaft 24b rotates, the sun gear 40 rotates. Since the large diameter gear portion 60a is engaged with the sun gear 40, when the sun gear 40 rotates, each planetary gear 60 rotates on its axis. Since the small diameter gear portion 60b is engaged with the ring gear 50, each planetary gear 60 revolves around the rotor shaft 24b as each planetary gear 60 rotates on its axis. Since each planetary gear 60 revolves around the rotor shaft 24b, the planetary carrier 70 rotates coaxially with the rotor shaft 24b. The rotation of the planetary carrier 70 rotates the wheel 90 and the tire 92 fixed to the planetary carrier 70. In this way, the planetary gear reducer 30 transmits the rotation of the rotor shaft 24b to the wheel 90. The planetary gear reducer 30 rotates the wheel 90 at a slower rotational speed than the rotor shaft 24b. Each planetary gear 60 has a large diameter gear portion 60a and a small diameter gear portion 60b, so that the reduction ratio can be increased.

[0017] In the in-wheel motor 10 of the first embodiment, a bearing 80 that rotatably supports a wheel 90 relative to a housing 12 is disposed in an outer circumferential region 84. The outer circumferential region 84 is a region that is generated when a planetary gear 60 having a large diameter gear portion 60a and a small diameter gear portion 60b is used. By providing the bearing 80 in the outer circumferential region 84, the space within the wheel 90 can be effectively utilized, and the in-wheel motor 10 can be made smaller in size.

[0018] In the above-described first embodiment, the ring gear 50 is fixed to the housing 12, and the planetary carrier 70 is fixed to the wheel 90. However, as shown in FIG. 2, the ring gear 50 may be fixed to the wheel 90, and the planetary carrier 70 may be fixed to the housing 12. That is, the ring gear 50 may constitute a part of the rotating member, and the planetary carrier 70 may constitute a part of the fixed member. Even in this configuration, the wheel 90 can be rotated at a slower speed than the rotor shaft 24b by the planetary gear reducer 30. Even in this case, the in-wheel motor can be made smaller by providing the bearing 80 in the outer circumferential area 84 between the ring gear 50 and the wheel 90.

[0019] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and achieving one of the objectives itself has technical utility. [Explanation of symbols]

[0020] 10: In-wheel motor 12: Housing 24b: Rotor shaft 30: Planetary gear reducer 40: Sun gear 50: Ring gear 60: Planetary gear 60a: Large diameter gear section 60b: Small diameter gear section 70: Planet carrier 80: Bearing 84:Outer area 90: Wheel 92: Tires

Claims

[Claim 1] An in-wheel motor, A fixing member fixed to a body of a vehicle; A rotating member that rotates together with the tire; a motor having a shaft that rotates relative to the fixed member; a planetary gear reducer that transmits rotation of the shaft to the rotating member; having The planetary gear reducer is A sun gear fixed to the shaft; A ring gear; a plurality of planetary gears disposed between the sun gear and the ring gear; a planetary carrier that rotatably supports each of the planetary gears; having One of the planetary carrier and the ring gear constitutes a part of the rotating member, Each of the planetary gears has a small diameter gear portion that engages with the ring gear, and a large diameter gear portion that is shifted from the small diameter gear portion in the axial direction of the shaft and engages with the sun gear, In a radial direction of the shaft, the large diameter gear portion protrudes outward from the ring gear, a bearing that rotatably supports the rotating member relative to the fixed member is disposed in an outer peripheral region that overlaps with the ring gear when viewed along the radial direction, is located on the outer peripheral side of the ring gear in the radial direction, and is located on the inner peripheral side of the outer peripheral end of the large diameter gear portion in the radial direction; In-wheel motor.

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