Steering Rack Elastic Member Groove Design
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Solution Overview
Problem
The existing shock absorbing devices for rack and pinion type steering systems face limitations in increasing shock absorbing capability due to the potential for buckling when the elastic member is compressed, as its axial length cannot be significantly increased without compromising its structural integrity and noise reduction.
Innovation Solution
A shock absorbing device with a cylindrical elastic member featuring alternating grooves on its outer and inner surfaces, which allows for bending deformation instead of compressive deformation, preventing buckling and enhancing energy absorption, and is positioned within an enlarged diameter portion of the rack housing to prevent radial deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the axial length of the elastic member is increased to increase the deformation stroke, then the shock absorbing capability is improved, but the elastic member becomes prone to buckling under compressive load
Solution Approach 1:
The elastic member is segmented by forming grooves on its outer and inner circumferential surfaces. These grooves divide the continuous elastic structure into multiple segments that can bend independently, allowing the member to achieve greater deformation stroke through sequential bending of segments rather than uniform compression, thereby preventing buckling
Solution Approach 2:
The invention transitions the deformation mechanism from one-dimensional compressive deformation to multi-dimensional bending deformation. By forming grooves that enable the elastic member to bend in multiple directions along its length, the deformation stroke is increased without requiring a longer axial length, thus maintaining buckling resistance while achieving greater shock absorption
2Force
If the cross sectional area of the elastic member is increased to increase the spring constant, then the shock absorbing capability is improved, but the elastic member cannot fit within the limited space of the rack housing
Solution Approach 1:
Instead of uniformly increasing the cross-sectional area of the entire elastic member, the invention applies local quality by forming grooves only in specific regions of the elastic member. This allows certain segments to have enhanced bending capability where needed, while maintaining a compact overall cross-section that fits within the rack housing constraints
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 effectively increases the shock absorbing capability of the device while minimizing the tendency to buckle, thereby improving the overall energy absorption and maintaining structural integrity.
Implementation Method 1
the part of the elastic member adjacent to each groove is caused to undergo a bending deformation so as to fill the groove before undergoing a compressive deformation
Implementation Method 2
the deformation stroke by which the elastic member is allowed to deform without incurring the buckling of the elastic member is increased, and this amounts to increasing the amount of the energy that can be absorbed by the elastic member
Data Source
AI summary
A shock absorbing device for a rack and pinion type steering device includes a rack shaft, a rack housing, a stopper portion formed in an end part of the rack shaft, a stopper engaging portion provided on the rack housing to define a stroke end position for the rack shaft by engaging the stopper portion, a stepped portion formed on the rack shaft, a shoulder portion formed in an enlarged diameter portion of the rack housing, and a cylindrical elastic member fitted on the rack shaft such that the elastic member is pressed in the axial direction of the rack shaft by the stepped portion and the shoulder portion. The elastic member is formed with grooves on each of an outer circumferential surface and an inner circumferential surface thereof. Such shock absorbing device for a rack and pinion type steering device has a high shock absorbing capability.