Steering Lock Slip Ring Torque Stabilization
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Solution Overview
Problem
Conventional steering lock mechanisms face high machining costs due to strict dimensional accuracy requirements and sensitivity to fastening margin changes, leading to increased costs and residual stress issues.
Innovation Solution
A steering apparatus with a key lock collar and a cylindrical slip ring, where the key lock collar abuts the slip ring at multiple points axially and forms clearances for deformation, reducing load displacement and stabilizing slip torque, while the slip ring includes protruded portions for radial deformation and the key lock collar has varying diameters for stable rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the key lock collar is press-fitted on the steering shaft with strict dimensional accuracy management, then the slip torque is stabilized, but the machining cost rises
Solution Approach 1:
A slip ring is introduced as an intermediary component between the key lock collar and the steering shaft. The slip ring absorbs dimensional variations and fastening margin changes through its elastic deformation, thereby stabilizing the slip torque without requiring strict dimensional accuracy in the press-fit portions. This mediator eliminates the need for costly tight tolerance machining while maintaining reliable slip torque characteristics.
Solution Approach 2:
The slip ring's elastic properties are utilized to change the mechanical parameters of the system. By allowing radial deformation of the slip ring within its elastic limit, the system accommodates dimensional variations in the press-fit interface. The slip ring transforms rigid dimensional requirements into flexible elastic deformation, enabling stable slip torque with relaxed machining tolerances.
2Reliability
If the slip ring is made with high spring constant to ensure slip torque, then the slip torque is maintained, but the dimensional accuracy and fastening margin management become more difficult
Solution Approach 1:
The slip ring is designed with optimized elastic properties that balance spring constant and deformation capacity. Rather than using a high spring constant that would require precise fastening margin control, the slip ring uses moderate elasticity to absorb dimensional variations. This parameter optimization allows the slip ring to maintain slip torque while being tolerant of manufacturing variations in the press-fit interface.
3Reliability
If the fastening margin is reduced to minimize gap between shaft and collar, then the slip torque is stabilized, but the slip ring becomes sensitive to residual stress and requires additional processing steps
Solution Approach 1:
Instead of minimizing the fastening margin to zero or near-zero values, the invention uses a moderate fastening margin that is sufficient to maintain slip torque stability. This partial action approach avoids the need for additional stress-relief processing steps like annealing, while still achieving reliable slip torque characteristics. The slip ring's elastic deformation compensates for the moderate gap without requiring excessive fastening precision.
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 stabilizes slip torque, enlarges the dimensional allowance range, and reduces machining costs by allowing for more flexible assembly and reduced dimensional accuracy management.
Implementation Method 1
a cylindrical slip ring being interposed between the steering shaft and the key lock collar in radial directions, wherein the key lock collar has a shape that reduces a change in load against displacement (a quantity of deformation in radial directions) of the slip ring
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A steering apparatus (1) is provided, which includes: a key lock collar (5) being fitted on a steering shaft (2) and restricted from rotating by a steering lock mechanism when performing a steering lock; and a slip ring (8) being interposed between the steering shaft (2) and the key lock collar (5) in radial directions, wherein the slip ring (8) includes a plurality of protruded portions (9) protruding outwardly or inwardly in the radial directions and being provided in a circumferential direction, and an inner peripheral portion of the key lock collar (5) covering the slip ring (8) is formed with large-diameter portions (7a) and small-diameter portions (7b) in the axial direction, thereby further stabilizing slip torque of the key lock and enlarging a range of dimensional allowance.