Automatic Transmission Thrust Load Routing
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Solution Overview
Problem
Helical gears in automatic transmissions generate thrust loads that increase friction in thrust bearings, impairing the efficiency of multi-speed and wide-range transmissions due to the axial direction thrust load from meshing reaction forces.
Innovation Solution
The automatic transmission design minimizes friction by transmitting thrust loads directly from planetary gear mechanisms to the transmission case using specific clutch and brake configurations, including thrust bearings between key components, and optimizing the transmission route to avoid passing through multiple bearings, thereby reducing friction loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple thrust bearings are disposed between multiple rotating members to support thrust loads from helical gears, then the thrust loads can be supported, but friction loss increases and transmission efficiency decreases
Solution Approach 1:
The invention extracts the thrust bearing from the transmission path between the planetary gear mechanism and the input shaft. Specifically, the thrust bearing is removed from the connection path between the ring gear and the input shaft, allowing the thrust load to be directly transmitted to the transmission case without passing through the bearing, thereby reducing friction loss while maintaining thrust load support capability
Solution Approach 2:
The invention introduces the transmission case as an intermediary to directly receive and support the thrust load from the planetary gear mechanism. By making the transmission case the direct load-bearing component, the thrust load is transmitted outside the rotating member connection path, avoiding friction in the thrust bearing while still achieving effective thrust load support
2Strength
If thrust loads are transmitted through multiple bearings and rotating members, then the load can be distributed, but friction loss increases
Solution Approach 1:
The invention extracts the thrust bearing from the load transmission path between the planetary gear mechanism and the input shaft. The thrust bearing is removed from the connection path involving the ring gear, allowing thrust load to be directly transmitted to the transmission case without passing through the bearing, thereby reducing friction loss while maintaining thrust load support capability
Solution Approach 2:
The transmission case serves as an intermediary that directly receives the thrust load from the planetary gear mechanism. This intermediary structure allows the thrust load to be transmitted outside the rotating member connection path, avoiding friction in the thrust bearing while achieving effective load distribution and support
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces friction in thrust bearings, enhancing the efficiency and performance of the automatic transmission by minimizing the transmission of thrust loads through multiple parts, thus maintaining the advantages of multi-speed and wide-range capabilities.
Implementation Method 1
friction of each thrust bearing supporting the thrust load increases and may impair advantages of a multi-speed and wide-range automatic transmission
Data Source
AI summary
An automatic transmission includes a thrust bearing α disposed between a third sun gear of a third planetary gear mechanism and a second sun gear of a second planetary gear mechanism. Accordingly, transmitting a thrust load acting on the second sun gear of the second planetary gear mechanism from the thrust bearing to an input shaft via the third sun gear of the third planetary gear mechanism can avoid, as much as possible, a case where the thrust load is transmitted from the third planetary gear mechanism to the input shaft via a fourth planetary gear mechanism, and reduce friction loss of multiple thrust bearings interposed among elements or the like of the third planetary gear mechanism and the fourth planetary gear mechanism.