Steering Shaft Stopper Elastic Structure for Finer Load Absorption
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Solution Overview
Problem
The existing vehicular steering devices have two-stage load absorbing characteristics which are not sufficient to enhance the steering feeling, and there is a need for further fine load absorbing capabilities.
Innovation Solution
A vehicular steering device with an elastic body that includes an annular first elastic portion and an annular second elastic portion, where the second clearance is larger than the first clearance, allowing for optimized load absorbing characteristics by designing appropriate clearances between the housing and the elastic body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the elastic body uses a two-stage structure with low-spring-rate and high-spring-rate portions arranged side by side, then the load absorbing characteristics are improved, but the steering feeling cannot be sufficiently enhanced due to coarse two-stage characteristics
Solution Approach 1:
The elastic body is divided into multiple elastic portions (first, second, and third elastic portions) with different spring rates arranged in series along the compression direction. Each portion has a different thickness and material hardness, creating multiple distinct compression stages that provide finer load absorbing characteristics compared to the conventional two-stage structure, thereby enhancing steering feeling while maintaining reliability.
Solution Approach 2:
Different regions of the elastic body are assigned different local properties: the first elastic portion has a larger thickness and lower spring rate for initial compression, the second elastic portion has intermediate properties, and the third elastic portion has smaller thickness and higher spring rate for final compression. This local differentiation creates a multi-stage compression characteristic that refines the load absorbing behavior.
2Ease of manufacture
If the elastic body is designed with uniform structure, then the manufacturing is simple, but the load absorbing characteristics are coarse and cannot provide fine steering feedback
Solution Approach 1:
The elastic body is segmented into multiple distinct elastic portions with different geometric and material properties. This segmentation enables precise control over the compression characteristics at different stages, achieving fine load absorbing characteristics while still allowing for integrated molding that maintains manufacturing simplicity.
Solution Approach 2:
The patent varies key parameters including thickness, material hardness, and cross-sectional area across different elastic portions. The first elastic portion has greater thickness and lower hardness, the second has intermediate values, and the third has lesser thickness and higher hardness. These parameter changes create distinct compression stages that provide fine load absorbing characteristics.
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 optimized elastic body design provides further fine load absorbing characteristics, enhancing the steering feeling by effectively attenuating both normal steering loads and shock loads.
Implementation Method 1
an elastic body which is formed of an annular integral molding component with elasticity... When the elastic body receives small abutment load by a normal steering operation, the low-spring-rate portion is deformed and absorbs such load. When the elastic body receives large shock load, the low-spring-rate portion and the high-spring-rate portion are deformed, and absorb such load.
Data Source
AI summary
A vehicular steering device includes a turning shaft, a housing storing therein the turning shaft, a stopper provided at a shaft end of the turning shaft, and an annular elastic body. An opening of the housing is formed in a U-shaped cross-sectional shape and in an annular shape opened toward the stopper by an external cylinder portion and an internal cylinder portion. The elastic body includes a first elastic portion and a second elastic portion. The first elastic portion is supported by an inner circumferential surface of the external cylinder portion and the bottom surface, and is provided with a first clearance from an outer circumferential surface of the internal cylinder portion. The second elastic portion extends toward the stopper from the first elastic portion, and is provided with a second clearance larger than the first clearance from the inner circumferential surface of the external cylinder portion.