Oil Passage Structure for Lightweight Shaft Support Rigidity
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Solution Overview
Problem
Reducing the weight of a cover member in an automatic transmission while maintaining the support rigidity of the shaft, as simply reducing the outer diameter of the support wall portion can compromise the shaft's rigidity due to the presence of an oil passage along the rotation axis.
Innovation Solution
Incorporating a support wall portion surrounding an insertion hole, a first tubular member externally fitting on the support wall portion, and a second tubular member internally fitting in the support wall portion, with an oil passage located between the support wall portion and the tubular members, allowing for reduced weight without compromising support rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the outer diameter of the support wall portion is reduced to reduce weight, then the weight of the cover member is reduced, but the support rigidity of the shaft deteriorates due to the presence of an oil passage
Solution Approach 1:
The support wall portion is divided into multiple segments: the main support wall, an outer tubular member, and an inner tubular member. This segmentation allows the oil passage to be positioned in the gaps between segments rather than cutting through the entire wall thickness, thereby maintaining structural integrity while enabling weight reduction through optimized material distribution.
Solution Approach 2:
The inner tubular member is nested within the outer tubular member, both fitting within the support wall portion. This nested configuration creates multiple concentric layers that provide structural reinforcement while allowing the oil passage to flow through the annular spaces between layers, effectively solving the contradiction between weight reduction and rigidity maintenance.
2Weight of moving object
If the outer diameter of the support wall portion is reduced, then weight is reduced, but the structural integrity and support function deteriorate
Solution Approach 1:
By segmenting the support wall into multiple functional layers (main wall, outer tube, inner tube), each layer can be optimized for specific functions: the main wall provides overall structural support, while the nested tubular members provide localized reinforcement at critical areas, thereby maintaining reliability with reduced overall diameter.
Solution Approach 2:
The support wall portion employs a composite structure combining the main support wall material with tubular member materials, creating a multi-material system that achieves superior strength-to-weight ratio compared to a single-material wall, thus maintaining support function while reducing weight.
Data Source
AI summary
An oil passage structure, includes a first tubular member configured to externally fit on a support wall portion and a second tubular member configured to internally fit in the support wall portion and supports an outer periphery of the shaft. An oil passage along a rotation axis direction of the shaft is provided at at least one of a location between the support wall portion and the first tubular member and a location between the support wall portion and the second tubular member.