Steering Rack Shock Absorber with Dual Spring Rate Segmentation
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Solution Overview
Problem
In rack-and-pinion steering apparatuses, existing shock absorption methods fail to effectively manage both small and large shocks, leading to direct transmission of large shocks to the rack and pinion teeth, potentially causing damage.
Innovation Solution
A steering apparatus with a shock-absorbing member featuring a low-spring rate portion and a high-spring rate portion, where the low-spring rate portion is compressed first for small shocks and the high-spring rate portion is engaged for larger shocks, preventing direct impact on the rack and pinion teeth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single elastic body is used for shock absorption, then the structure is simple, but it cannot effectively absorb both small and large shocks
Solution Approach 1:
The elastic body is divided into multiple independent cushioning portions with different spring rates. Each portion (first through fourth cushioning portions) has a specific spring rate, creating a segmented structure that can handle different shock magnitudes independently, thus resolving the contradiction between structural simplicity and effective shock absorption.
Solution Approach 2:
Different portions of the elastic body are assigned different local properties (spring rates). The first and second cushioning portions have lower spring rates for small shocks, while the third and fourth cushioning portions have higher spring rates for large shocks. This local differentiation allows the single elastic body to effectively absorb both small and large shocks.
2Reliability
If the steered shaft is allowed to move freely to absorb shock, then the shock is absorbed, but the rack and pinion teeth are damaged by direct impact
Solution Approach 1:
The elastic body is pre-installed between the steered shaft and housing to provide cushioning before shock occurs. The multiple cushioning portions with different spring rates are ready in advance to absorb shocks of various magnitudes, preventing direct impact on the rack and pinion teeth before damage can occur.
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 absorbs and damps both small and large shocks, protecting the rack and pinion teeth from damage and ensuring smooth operation.
Implementation Method 1
the shock absorbing member includes a low-spring rate portion and a high-spring rate portion having a higher spring rate than the low-spring rate portion in the vehicle width direction
Implementation Method 2
a spring rate is a force necessary for compressing the shock absorbing member (elastic body) by a unit length
Implementation Method 3
the low-spring rate portion is chiefly deformed when a shock (load) inputted to the shock absorbing member is small. When a further larger shock is inputted from the steered wheel to the steered shaft, the high-spring rate portion is deformed in addition to the low-spring rate control portion
Data Source
AI summary
A steering apparatus includes a rack shaft moving in a vehicle width direction for steering steered wheels, a rack end in a moving side, which is provided in the rack shaft and integrally moving with the rack shaft, a housing body in a fixed side, which does not move in the vehicle width direction and controls the movement of the rack shaft by collision from the rack end to the housing body and a shock absorbing member provided between the rack end and the housing body to absorb a shock from the rack end to the housing body, in which the shock absorbing member includes a low-spring rate portion and a high-spring rate portion having a higher spring rate than that of the low-spring rate portion in the vehicle width direction.