Steering Column Rake Lock Cam Mechanism for Impact Stability
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Solution Overview
Problem
Traditional steering column locks face challenges in providing adequate load handling and maintaining rake position stability during vehicle collisions, with interlocking teeth limiting adjustment positions and friction locks being unreliable.
Innovation Solution
A position lock mechanism featuring an outer cam, inner cam with a slotted aperture, and a tooth lock that rotates between locked and unlocked positions, allowing for fine adjustments and secure engagement with a rake lock tooth wall, while maintaining stability during impact events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If interlocking teeth are used to provide vertical stability and prevent upward steering column displacements, then load handling capability is improved, but the number of available adjustment positions is limited to a predefined finite set
Solution Approach 1:
The steering column is divided into modular components including a telescoping assembly with separate shaft and jacket portions, and a rake adjustment assembly with distinct locking and adjustment mechanisms. This segmentation allows independent optimization of each component for both strength and adjustability.
Solution Approach 2:
The locking mechanism transitions from static interlocking teeth to a dynamic cam-based system with movable locking members that can engage at multiple positions along the rake adjustment range, providing continuous adjustment capability while maintaining secure locking.
2Measurement precision
If the size of interlocking teeth is decreased to provide finer adjustments, then adjustment precision is improved, but position assurance and tactile sensation are decreased
Solution Approach 1:
A cam surface acts as an intermediary between the locking member and the steering column shaft, translating small rotational movements into precise linear positioning while maintaining large contact areas for secure engagement and tactile feedback.
Solution Approach 2:
The cam surface employs curved geometry to provide smooth, continuous adjustment motion while maintaining consistent contact pressure and engagement force throughout the adjustment range, ensuring both precision and reliability.
3Measurement precision
If friction locks are used to provide fine adjustments, then adjustment precision is improved, but reliability is sacrificed due to susceptibility to unintended releases
Solution Approach 1:
The mechanism merges positive mechanical locking through cam surface engagement with friction-based holding, combining the reliability of interlocking mechanisms with the precision of friction locks while eliminating the susceptibility to unintended releases through proper geometric design.
Solution Approach 2:
The locking mechanism uses composite structural design combining rigid cam surfaces for positive engagement with friction surfaces optimized for precise positioning, creating a hybrid system that achieves both reliability and precision.
4Loss of energy
If the steering column is designed to disengage the shaft and jacket assembly from the column mounting bracket during collapse, then energy absorption capability is improved, but rake lock stability may be compromised
Solution Approach 1:
The locking mechanism is pre-configured with independent support structures and energy absorption pathways that allow the shaft and jacket to disengage from the mounting bracket while the rake lock remains engaged through alternative support paths, maintaining stability during collapse.
Solution Approach 2:
The steering column is segmented into independent functional zones: the rake adjustment assembly with its own support structure that remains stable during collapse, and the telescoping assembly that disengages for energy absorption, allowing simultaneous operation of both functions.
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 improved reliability and security in adjusting and locking the steering column's rake position, enabling controlled energy absorption and maintaining stability during vehicle impacts.
Implementation Method 1
The position lock includes an outer cam and an inner cam
Implementation Method 2
Other proposed solutions involve the use of frictions locks
Data Source
AI summary
A position lock for a steering column assembly is provided. The position lock includes an outer cam. Also included is an inner cam defining a slotted aperture to receive a rake bolt operatively coupled to the outer cam, the slotted aperture facilitating shuttling movement of the rake bolt therein. Further included is a tooth lock operatively coupled to the inner cam, the tooth lock rotatable between an unlocked position and a locked position. Yet further included is a pin extending through the inner cam and operatively coupled to the outer cam, and rotation of the outer cam facilitates movement of the tooth lock out of engagement with the rake lock tooth wall when rotating between the locked position and the unlocked position.