Steering Lock Camshaft Segmentation for Tamper Resistance
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Solution Overview
Problem
Existing steering lock devices are vulnerable to unauthorized unlocking when tampered with from outside, as they lack effective mechanisms to resist large loads applied to the lock actuation cam, potentially allowing unauthorized access to the steering mechanism.
Innovation Solution
A steering lock device design featuring a camshaft with a low-strength connection between the projection and shaft portion, where the interlock cam is configured to separate from the shaft when a load exceeding a predetermined strength is applied, preventing unauthorized rotation of the camshaft and thus maintaining the locked state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the projection is made exposed from the housing to allow operation, then the ease of operation is improved, but the vulnerability to unauthorized unlocking increases
Solution Approach 1:
The camshaft is designed with a low-strength portion at the connection between the projection and shaft portion that will break under excessive load before the lock bar can be disengaged. This preliminary failure mode prevents unauthorized unlocking by ensuring that any attempt to apply excessive force to operate the projection will result in the projection breaking off, thereby maintaining the locked state.
2Reliability
If the connection between projection and shaft portion is made strong, then the reliability is improved, but the resistance to tampering decreases
Solution Approach 1:
The camshaft exhibits non-uniform strength distribution: the low-strength portion is localized specifically at the connection between the projection and shaft portion, while other parts of the camshaft maintain normal strength. This local weakness ensures that under tampering loads, only the projection connection fails while the rest of the locking mechanism remains intact and functional.
3Object-affected harmful factors
If the projection is designed to separate under load, then the resistance to tampering is improved, but the structural integrity is compromised
Solution Approach 1:
The camshaft is effectively segmented into two parts: the shaft portion and the projection, connected by a low-strength portion. This segmentation allows the projection to separate from the shaft portion under excessive load, providing tamper resistance while the shaft portion and lock mechanism remain structurally intact.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A steering lock device (1) includes a camshaft (24) including a shaft portion (24) having an axis (L1), a lock actuation cam (41) that radially projects from a first position of the shaft portion (24) in an axial direction, and a projection (43) that radially projects from a second position of the shaft portion (24) in the axial direction; a housing (2) rotatably accommodating the camshaft (24); and a lock bar (22) moved by the lock actuation cam (41) in a locking direction or an unlocking direction when the camshaft (24) is rotated about the axis (L1) when a key cylinder (7) is operated by a mechanical key (80).The camshaft (24) is configured so that the projection (43) is separated from the shaft portion (24) if a load exceeding a predetermined strength acts on the projection (43) of the camshaft (24).