Steering Column Lock Collar Geometry for Torque-Safe Key Locking
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Solution Overview
Problem
Existing steering column devices with lock mechanisms face issues where excessive torque can break the lock key, rendering the antitheft function ineffective.
Innovation Solution
A steering column device with a key lock collar featuring concave and convex parts, and a cylindrical portion with adjustable outer diameter, ensures an appropriate frictional force is maintained between the steering shaft and the key lock collar, preventing lock key breakage while allowing necessary steering operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the frictional force between the steering shaft and key lock collar is increased to prevent lock key breakage, then the reliability of the lock mechanism is improved, but the ease of operation for steering is worsened
Solution Approach 1:
The key lock collar is designed with non-uniform outer diameter along its axial direction, creating different frictional characteristics in different regions. The first portion (with larger outer diameter) provides higher friction to prevent lock key breakage, while the second portion (with smaller outer diameter) provides lower friction to ensure smooth steering operation. This local differentiation of frictional properties resolves the contradiction between reliability and ease of operation.
Solution Approach 2:
The invention changes the geometric parameter (outer diameter) of the key lock collar along its axial direction to control the frictional force. By varying the outer diameter between the first and second portions, the frictional characteristics are adjusted to achieve both high reliability (preventing lock key breakage) and ease of operation (smooth steering).
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 solution provides a stable and appropriate frictional force, preventing lock key breakage under excessive torque while ensuring smooth steering operation, thus enhancing the antitheft functionality of the steering column device.
Implementation Method 1
a frictional force generated between the outer peripheral surface of the steering shaft and the inner peripheral surface of the key lock collar
Data Source
AI summary
A steering shaft is rotatably provided inside an outer column and an inner column. A key lock collar is mounted on an outer peripheral surface of the steering shaft, the outer peripheral surface facing the outer column. The key lock collar includes a key lock collar body and a cylindrical portion. Multiple concave parts and convex parts extending in the axial direction are provided on an outer peripheral part of the key lock collar body along the circumferential direction. A lock key is engaged with the concave parts from adjacent to the outer column, and thus the rotation of the steering shaft with respect to the outer column is restricted. An outer diameter of the cylindrical portion is smaller than an outer diameter of the convex parts and larger than an outer diameter of the concave parts.