CN-121993554-A - Power transmission device

Abstract

The invention provides a power transmission device. The power transmission device is provided with a sun gear fixed to a rotatable shaft, a ring gear coaxially arranged with the sun gear and fixed to a housing accommodating a planetary gear mechanism, a planetary gear meshing with the sun gear and the ring gear, and a carrier rotatably supporting the planetary gear, coaxially arranged with the sun gear, and rotatably supported by the housing, wherein the sun gear and the ring gear are bevel gears, respectively, the torsion angle of the teeth of the sun gear and the torsion angle of the teeth of the ring gear are set so that the axial thrust force acting on the sun gear is opposite to the axial thrust force acting on the ring gear, and a load transmission path for transmitting the axial thrust force acting on the sun gear and the axial thrust force acting on the ring gear is further provided between the sun gear and the ring gear, and the load transmission path includes at least a part of the carrier.

Inventors

• Kyoguchi Masato

Assignees

• 丰田自动车株式会社

Dates

Publication Date

20260508

Application Date

20251106

Priority Date

20241107

Claims (7)

1. 1. A power transmission device is provided with a planetary gear mechanism and a housing accommodating the planetary gear mechanism, The planetary gear mechanism includes: A sun gear fixed to a rotatable shaft; A ring gear coaxially arranged with the sun gear and fixed to the housing; a planetary gear meshed with the sun gear and the ring gear, and A carrier rotatably supporting the planetary gear, disposed coaxially with the sun gear, and rotatably supported by the housing, The sun gear and the gear ring are respectively helical gears, The torsion angle of the teeth of the sun gear and the torsion angle of the teeth of the ring gear are set so that the axial thrust force acting on the sun gear is opposite to the direction of the axial thrust force acting on the ring gear, The power transmission device further includes a load transmission path between the sun gear and the ring gear, the load transmission path transmitting an axial thrust force acting on the sun gear and an axial thrust force acting on the ring gear, The load transmission path is configured to include at least a part of the carrier.
2. 2. The power transmission device according to claim 1, wherein, The load transmission path includes: a first bearing provided in a path between the sun gear and the carrier, and And the second bearing is arranged on a path between the gear ring and the planetary carrier.
3. 3. The power transmission device according to claim 2, wherein, The carrier is coupled to a differential case accommodating a differential device, The first bearing is sandwiched by the sun gear and the differential case.
4. 4. The power transmission device according to claim 2, wherein, The load transmission path includes a structure extending from the ring gear, The second bearing is sandwiched by the structural body and the carrier.
5. 5. The power transmission device according to claim 4, wherein, The structure is integrally formed with the ring gear.
6. 6. The power transmission device according to claim 1, wherein, The planetary gear is a stepped pinion having a large-diameter pinion meshing with the sun gear on one side in an axial direction parallel to the shaft and a small-diameter pinion meshing with the ring gear on the other side in the axial direction, The load transmission path is provided on the other side of the large-diameter pinion gear in the axial direction.
7. 7. The power transmission device according to claim 1, wherein, The torsion angle of the teeth of the sun gear and the torsion angle of the teeth of the ring gear are set so that the magnitude of the axial thrust force acting on the sun gear is equal to the magnitude of the axial thrust force acting on the ring gear.

Description

Power transmission device Technical Field The technology disclosed in the present specification relates to a power transmission device provided with a planetary gear mechanism and a housing accommodating the planetary gear mechanism. Background As one of the power transmission devices, patent document 1 discloses a transaxle that transmits power of an electric motor to an axle via a planetary gear reducer and a differential device. According to patent document 1, a planetary gear reducer is a planetary gear mechanism having a sun gear formed on an output shaft of an electric motor as an input element, a ring gear fixed to a housing accommodating the planetary gear reducer as a reaction force element, and a carrier as an output element. The carrier supports a stepped pinion having a large diameter pinion engaged with the sun gear and a small diameter pinion engaged with the ring gear so as to be rotatable and revolvable. Further, patent document 1 discloses a case where each gear constituting the planetary gear reducer is a bevel (helical gear). Prior art literature Patent literature Patent document 1 Japanese patent laid-open publication No. 2021-110374 Disclosure of Invention Problems to be solved by the invention In the planetary gear mechanism described above, axial thrust force acts on the ring gear in association with the case where the ring gear is a helical gear. The housing fixing the ring gear receives an axial thrust force acting on the ring gear. Therefore, in the case, strength needs to be ensured in order to receive the axial thrust force acting on the ring gear, and there is a problem that the case is made thick, and the case is made large. Means for solving the problems Disclosed is a power transmission device provided with a planetary gear mechanism and a housing that houses the planetary gear mechanism. The planetary gear mechanism includes a sun gear fixed to a rotatable shaft, a ring gear coaxially arranged with the sun gear and fixed to the housing, a planetary gear meshing with the sun gear and the ring gear, and a carrier rotatably supporting the planetary gear, coaxially arranged with the sun gear, and rotatably supported by the housing. The sun gear and the gear ring are respectively helical gears. The torsion angle of the teeth of the sun gear and the torsion angle of the teeth of the ring gear are set so that the axial thrust force acting on the sun gear is opposite to the direction of the axial thrust force acting on the ring gear. The power transmission device further includes a load transmission path between the sun gear and the ring gear, the load transmission path transmitting an axial thrust force acting on the sun gear and an axial thrust force acting on the ring gear, the load transmission path including at least a part of the carrier. According to the above configuration, the axial thrust force acting on the ring gear and the force opposite to the axial thrust force acting on the ring gear, that is, the axial thrust force acting on the sun gear are transmitted to the load transmission path. Therefore, at least a part of the axial thrust force acting on the ring gear is offset by the axial thrust force acting on the sun gear. Thus, the strength required for the housing is reduced to receive the axial thrust force acting on the ring gear, and the housing can be prevented from being enlarged. Further, since the load transmission path is configured to include at least a part of the carrier, an increase in the number of components can be suppressed when the load transmission path is provided. Drawings Fig. 1 is a diagram simply showing the structure of a power transmission device. Fig. 2 is a perspective view schematically showing the appearance of the case and the contents in the case. Fig. 3 is a partial cross-sectional view mainly showing the planetary gear mechanism in the housing. Fig. 4 is a view schematically showing a vehicle equipped with a power transmission device from the side. Description of the reference numerals 10, Power transmission device 11, motor 20, stator 21, rotor 22, rotor shaft 23, planetary gear mechanism 30, sun gear 31, 32, ring gear 33, planetary gear 33a, large-diameter pinion 33b, small-diameter pinion 34, carrier 35, differential case 40, load transmission path 41, first part 42, second part 43, structure 48, first bearing 49, second bearing 50, differential device, ax, shaft Detailed Description Hereinafter, the main features of the embodiments to be described are listed. The load transmission path may include a first bearing on a path between the sun gear and the carrier, and a second bearing on a path between the ring gear and the carrier. According to the above configuration, the first bearing and the second bearing are used each time the load transmission path is formed, so that the smooth rotation of the sun gear and the carrier can be ensured, and the load transmission path can be formed while suppressing an increase in the number of compo