Steering Column Lock Collar Geometry for Key Breakage Prevention
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Solution Overview
Problem
Existing steering column lock mechanisms can be compromised by excessive torque, leading to breakage of the lock key and loss of antitheft functionality.
Innovation Solution
A steering column device with a key lock collar featuring alternating concave and convex parts and a cylindrical portion with adjusted dimensions to generate a uniform frictional force, ensuring the lock key is not broken under strong force while allowing smooth 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 under strong torque, then the lock key durability is improved, but the steering operation becomes interfered with in the unlocked state
Solution Approach 1:
The key lock collar is designed with non-uniform outer diameter along its axial direction, creating different frictional force characteristics in different regions. The first end portion has a larger outer diameter to provide higher frictional force and prevent lock key breakage, while the second end portion has a smaller outer diameter to reduce frictional force and allow smooth steering operation. This local differentiation of geometric properties resolves the contradiction between durability and ease of operation.
2Strength
If the frictional force is set to be insufficient to destroy the lock key in the locked state, then the lock key is protected from breakage, but the antitheft function may be compromised
Solution Approach 1:
The key lock collar employs local quality differentiation through varying outer diameter along its axial length. The first end portion with larger outer diameter generates sufficient frictional force to maintain antitheft functionality by preventing unauthorized rotation, while the second end portion with smaller outer diameter provides reduced frictional force to protect the lock key from breakage during normal operation. This spatial variation in geometric properties allows simultaneous achievement of both objectives.
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 device provides a stable and appropriate frictional force that prevents lock key breakage and maintains steering functionality, enhancing the antitheft mechanism's effectiveness.
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
Figure 1
Figure 2
Figure 3~4
AI summary
A steering shaft 11 is rotatably provided inside an outer column 5 and an inner column 7. A key lock collar 15 is mounted on an outer peripheral surface of the steering shaft 11, the outer peripheral surface facing the outer column 5. The key lock collar 15 includes a key lock collar body 19 and a cylindrical portion 21. Multiple concave parts 19a and convex parts 19b extending in the axial direction are provided on an outer peripheral part of the key lock collar body 19 along the circumferential direction. A lock key 17 is engaged with the concave parts 19a from adjacent to the outer column 5, and thus the rotation of the steering shaft 11 with respect to the outer column 5 is restricted. An outer diameter D1 of the cylindrical portion 21 is smaller than an outer diameter D2 of the convex parts 19b and larger than an outer diameter D3 of the concave parts 19a.