Transmission device

Patent metadata

Field	Value
Publication number	US-11649882-B2
Application number	US-201917634113-A
Country	US
Kind code	B2
Filing date	Sep 11, 2019
Priority date	Sep 11, 2019
Publication date	May 16, 2023
Grant date	May 16, 2023

Abstract

A transmission device is formed by combining a planetary gear-type reduction gear and a differential device, wherein at least one of first and second planetary gear portions in a two-stage planetary gear has gear teeth that receive a thrust load due to meshing with opposing gear, a power-transmission case formed by joining a carrier to a differential case is rotatably supported on a transmission case. A pivot shaft of the planetary gear has one end thereof on the first planetary gear portion side supported on the power-transmission case via a first bearing and the other end on the second planetary gear portion side supported on the power-transmission case via a second bearing, and the thrust loads on one side and on the other side in an axial direction are supported only by the first bearing among the first and second bearings. Thus, a wall portion of the power-transmission case pivotably supporting the second planetary gear portion is reduced in size in the radial direction, contributing to a reduction in size of the transmission case in the radial direction.

First claim

The invention claimed is:

1. A transmission device comprising
a reduction gear having a sun gear, a ring gear that is disposed concentrically with the sun gear and is fixed to a transmission case, a plurality of planetary gears that mesh with the sun gear and the ring gear, and a carrier that rotatably supports the plurality of planetary gears via respective pivot shafts, and
a differential device having a differential case that receives rotational power from the reduction gear and a differential mechanism that is disposed within the differential case and distributes the rotational power between a pair of output shafts while allowing differential rotation,
the planetary gear being a two-stage planetary gear integrally having a first planetary gear portion meshing with the sun gear and a second planetary gear portion formed so as to have a smaller diameter than a diameter of the first planetary gear portion and meshing with the ring gear, at least one of the first and second planetary gear portions having gear teeth that receive a thrust load due to meshing with the opposing gear, and
a power-transmission case formed by joining the carrier to the differential case being rotatably supported on the transmission case,
wherein the pivot shaft has one end part thereof on the first planetary gear portion side supported on the power-transmission case via a first bearing and an other end part on the second planetary gear portion side supported on the power-transmission case via a second bearing, and the thrust loads on one side and on an other side in an axial direction are supported only by the first bearing among the first and second bearings.

2. The transmission device according to claim 1 , wherein the second planetary gear portion and the differential mechanism are disposed in the power-transmission case so that at least parts thereof overlap one another in the axial direction.

3. The transmission device according to claim 2 , wherein the transmission case is dividedly in the axial direction formed from a transmission case main body that has the ring gear fixed to an inner periphery thereof and a lid body that is detachably joined to the transmission case main body,
the power-transmission case can be inserted into the transmission case main body through mutually opposing faces of the transmission case main body and the lid body, and
an internal diameter of the ring gear is larger than the maximum external diameter of an end wall, supporting the second bearing, of the power-transmission case.

4. The transmission device according to claim 3 , wherein the end wall, close to the second planetary gear portion, of the power-transmission case comprises a plurality of pivot shaft support portions that support said other end of the pivot shaft via the second bearing, a recessed place that is recessed in an outside face of the end wall further inside in a radial direction than the second bearing and has a bottom face thereof positioned further inside in the axial direction than an outer end in the axial direction of the pivot shaft support portion, and a bearing boss portion that protrudes outward in the axial direction from the bottom face of the recessed place and is rotatably fitted onto and supports said one output shaft,
an outer peripheral part of the bearing boss portion is supported via a case support bearing on a support boss portion projectingly provided on an inner face of the transmission case, and
at least part of each of the case support bearing and the support boss portion is disposed within the recessed place.

5. The transmission device according to claim 4 , wherein the end wall, close to the second planetary gear portion, of the power-transmission case comprises a plurality of pivot shaft support portions that are formed so as to extend through the end wall in the axial direction and support the pivot shaft via the second bearing, and the bearing boss portion that is rotatably fitted onto and supports said one output shaft further inside than the second bearing in the radial direction,
a recess portion is formed in an outside face of the end wall further outside than the bearing boss portion in the radial direction and between at least two peripherally adjacent second bearings, and
an oil retaining member covering an outer part in the radial direction of an opening face of the recess portion and an outer part in the radial direction of an outer end in the axial direction of the second bearing is disposed so as to extend in a peripheral direction while straddling the recess portion and the second bearing.

6. The transmission device according to claim 3 , wherein the end wall, close to the second planetary gear portion, of the power-transmission case comprises a plurality of pivot shaft support portions that are formed so as to extend through the end wall in the axial direction and support the pivot shaft via the second bearing, and the bearing boss portion that is rotatably fitted onto and supports said one output shaft further inside than the second bearing in the radial direction,
a recess portion is formed in an outside face of the end wall further outside than the bearing boss portion in the radial direction and between at least two peripherally adjacent second bearings, and
an oil retaining member covering an outer part in the radial direction of an opening face of the recess portion and an outer part in the radial direction of an outer end in the axial direction of the second bearing is disposed so as to extend in a peripheral direction while straddling the recess portion and the second bearing.

7. The transmission device according to claim 2 , wherein the end wall, close to the second planetary gear portion, of the power-transmission case comprises a plurality of pivot shaft support portions that support said other end of the pivot shaft via the second bearing, a recessed place that is recessed in an outside face of the end wall further inside in a radial direction than the second bearing and has a bottom face thereof positioned further inside in the axial direction than an outer end in the axial direction of the pivot shaft support portion, and a bearing boss portion that protrudes outward in the axial direction from the bottom face of the recessed place and is rotatably fitted onto and supports said one output shaft,
an outer peripheral part of the bearing boss portion is supported via a case support bearing on a support boss portion projectingly provided on an inner face of the transmission case, and
at least part of each of the case support bearing and the support boss portion is disposed within the recessed place.

8. The transmission device according to claim 7 , wherein the end wall, close to the second planetary gear portion, of the power-transmission case comprises a plurality of pivot shaft support portions that are formed so as to extend through the end wall in the axial direction and support the pivot shaft via the second bearing, and the bearing boss portion that is rotatably fitted onto and supports said one output shaft further inside than the second bearing in the radial direction,
a recess portion is formed in an outside face of the end wall further outside than the bearing boss portion in the radial direction and between at least two peripherally adjacent second bearings, and
an oil retaining member covering an outer part in the radial direction of an opening face of the recess portion and an outer part in the radial direction of an outer end in the axial direction of the second bearing is disposed so as to extend in a peripheral direction while straddling the recess portion and the second bearing.

9. The transmission device according to claim 2 , wherein the end wall, close to the second planetary gear

Assignees

• Musashi Seimitsu Kogyo Kk

Inventors

• Asai Ryosuke
• Butta Naofumi
• NGUYEN Hoa Binh
• KATO Shiryu

Classifications

• F16H2057/02052

  Axle units; Transfer casings for four wheel drive · CPC title

• F16H57/082

  Planet carriers · CPC title

• F16H37/082 Primary

  and additional planetary reduction gears · CPC title

• B60K17/04

  characterised by arrangement, location or kind of gearing · CPC title

• B60Y2410/1022

  Concentric shaft arrangements · CPC title