Transaxle Case Boss Structure for Collision Crack Suppression
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Solution Overview
Problem
Existing transaxles face challenges in conserving space while effectively suppressing cracking of the case due to the presence of ribs that occupy space and concentrate stress during collisions.
Innovation Solution
The transaxle design incorporates boss portions that protrude in a manner to disperse stress, with the first boss portion extending further towards the vehicle member than the second, and optionally includes a tapered or stepped shape or a relieving portion to absorb impact, thereby preventing stress concentration on the lower portion of the second boss portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ribs are provided on the case to suppress cracking during collisions, then the case strength is improved, but the space conservation deteriorates because the ribs occupy additional space
Solution Approach 1:
The case is segmented into multiple boss portions (first boss portion and second boss portion) that are positioned at different heights. This segmentation allows each boss portion to independently absorb and disperse collision forces, achieving crack suppression without requiring additional space-consuming ribs throughout the case structure.
Solution Approach 2:
The solution transitions from a two-dimensional rib structure to a three-dimensional multi-level boss portion configuration. By arranging boss portions at different vertical levels (first boss portion higher than the second), the design utilizes the vertical dimension to分散 collision forces, achieving both space conservation and crack suppression.
2Reliability
If ribs are provided on the case to prevent cracking, then the reliability is improved, but the device complexity increases due to additional structural elements
Solution Approach 1:
The collision prevention function is merged into the existing case structure through the boss portions, which are integrated directly into the case body. This eliminates the need for separate rib structures or additional collision prevention components, maintaining reliability while reducing device complexity.
Solution Approach 2:
The boss portions serve multiple functions: they provide structural support for mounting the rotating electrical machine and gear, and simultaneously act as collision prevention elements that absorb and disperse impact forces. This multi-functionality reduces the need for separate components, simplifying the overall structure.
3Volume of moving object
If the first boss portion protrudes further than the second boss portion, then the space conservation is improved and stress dispersion is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The first boss portion is designed with a larger protrusion height than the second boss portion, creating local quality differences that optimize stress dispersion. The first boss portion (with greater protrusion) is positioned to receive the primary impact force, while the second boss portion provides secondary support, with each having tailored dimensions for its specific functional role.
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 design achieves space conservation and prevents cracking of the case by dispersing stress, eliminating the need for additional collision prevention materials and ensuring structural integrity during collisions.
Implementation Method 1
a relieving portion for relieving impact by being pressed in by the vehicle member when the vehicle member abuts the boss portion
Data Source
AI summary
The transaxle houses at least the rotating electrical machine and the gear in the case. The case of the transaxle includes a first boss portion protruding toward the vehicle member side and provided upward side, and a second boss portion protruding toward the vehicle member side and provided downward side, on a surface on which the vehicle member bent under the collision load abuts, and the vehicle member abuts against the upper portion of the first boss portion or the second boss portion before the lower portion of the second boss portion.