Self-aligning Detent Spring Assembly for Automatic Transmission
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Solution Overview
Problem
Conventional detent spring assemblies in automatic transmission park systems face challenges with positional variance and interference issues within the transmission case, particularly due to tolerance and space allocation concerns, leading to unwanted contact with the oil pan during vehicle operation.
Innovation Solution
A self-aligning detent spring assembly featuring a cage portion with opposing side walls and a deformable post, which retains a roller assembly coaxially aligned with the detent teeth, minimizing positional variance and optimizing alignment by orienting the roller assembly perpendicularly to the detent teeth, and a flat spring surface resting on the transmission housing to provide biasing and reaction forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional detent spring assembly is used with external positioning, then the spring can be easily installed, but it causes interference with the oil pan and has poor alignment between the detent roller and detent teeth
Solution Approach 1:
The cage portion integrates multiple functions: it positions the detent spring, orients the detent roller perpendicular to the detent teeth, and provides structural support. This merging of positioning and support functions into a single integrated component resolves the alignment issues while maintaining ease of installation as a unified assembly.
Solution Approach 2:
The cage portion acts as an intermediary component between the detent spring and the detent lever. It mediates the connection by providing a structured interface that ensures proper orientation and positioning, eliminating the interference problems that occur with direct external positioning methods.
2Ease of manufacture
If the detent spring is positioned externally to the transmission case, then installation is simpler, but tolerance issues cause interference within the crowded transmission housing
Solution Approach 1:
The detent spring assembly is nested within the transmission case housing, with the cage portion fitting into a designated space. This nested configuration eliminates interference with the oil pan and other components while maintaining a compact arrangement that is still easy to install as an integrated unit.
Solution Approach 2:
The cage portion extends in multiple dimensions to provide proper positioning and orientation. By utilizing three-dimensional space efficiently within the transmission case, the design accommodates the detent spring assembly without interfering with other components like the oil pan.
3Device complexity
If a conventional detent spring configuration is used, then the structure is simpler, but it does not optimize the alignment or minimize positional variance of the detent roller and detent teeth
Solution Approach 1:
The cage portion is pre-configured with specific geometric features (sides extending perpendicular to each other) that automatically establish the correct orientation and position of the detent roller relative to the detent teeth during assembly. This preliminary structuring eliminates the need for complex adjustment procedures while ensuring precise alignment.
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
The solution effectively reduces relative positional variance between the detent roller and detent lever, enhancing alignment and reducing interference within the transmission housing, thereby improving the assembly's operational reliability and reducing unwanted contact with the oil pan.
Implementation Method 1
the detent spring being connected to a roller on one end. The roller in turn rolls along in contact with the contours or side surfaces of the various detent teeth of the detent lever in response to rotation and/or vertical motion of the detent lever, with the detent spring in turn flexing or deflecting as needed to properly bias the roller
Implementation Method 2
The roller assembly is configured for rolling contact with a surface of one of the detent teeth in response to rotation of the detent lever
Data Source
AI summary
An automatic transmission has a park system with a shaft and a parking pawl. The shaft rotates in response to a gear shift lever, and a detent lever positions the parking pawl in response to rotation of the shaft. A detent spring assembly biases the detent lever and has a detent spring, cage, and roller assembly. The cage aligns the roller assembly, while the detent spring is connected to the cage at one end and has a flat reaction surface formed at a second end. A cage notch portion aligns the cage with the detent lever, and the roller assembly into a perpendicular orientation with detent lever teeth. The notch portion engages either a detent tooth or a stationary portion of an internal mode switch (IMS). A shaft inserts into a roller through a side hole in the cage to retain the roller assembly therewithin.