Steering Column Lock Mechanism with Pawl Actuator
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Solution Overview
Problem
Existing adjustable steering column assemblies face a conflict between adjustment mechanisms and safety release mechanisms, leading to inconsistent collapse loads during collisions, and there is a need for a cost-effective solution to axially constrain inner and outer steering column jackets while allowing necessary adjustments during normal operation.
Innovation Solution
An adjustable steering column assembly featuring a pivot pin with a pawl and actuator system that selectively engages and disengages the inner and outer jackets for telescoping movement, allowing for controlled collapse and adjustment, using a locking device with a pawl and actuator mechanism to manage the telescoping and raking movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking device is added to constrain the steering column jackets during collapse, then the collapse load curve repeatability is improved, but the device complexity increases
Solution Approach 1:
The locking device merges the pivot pin rotation function with the telescoping constraint function. The pivot pin serves dual purposes: enabling rake adjustment through rotation and, when locked, preventing telescoping movement during collapse. This integration eliminates the need for a completely separate locking mechanism, reducing overall device complexity while improving collapse reliability.
Solution Approach 2:
The actuator serves as an intermediary mechanism that translates pilot pin rotation into pawl engagement/disengagement. This intermediary component allows the system to switch between locked and unlocked states without requiring complex direct locking mechanisms, simplifying the overall design while ensuring reliable collapse constraint.
2Reliability
If the pivot pin is locked to prevent telescoping movement during collapse, then the safety performance is improved, but the adjustment capability during normal operation is reduced
Solution Approach 1:
The system dynamically transitions between two states: unlocked during normal operation allowing telescoping adjustment, and locked during collapse preventing telescoping movement. The actuator-enabled pawl mechanism provides this dynamic state change, ensuring the pivot pin can both enable adjustment when needed and constrain movement during collision for safety.
Solution Approach 2:
The system changes the constraint parameter of the pivot pin based on operating conditions. During normal operation, the pivot pin allows rotational movement for rake adjustment. During collapse, the locking device changes the parameter to prevent telescoping movement, ensuring safety while maintaining adjustment capability when required.
3Measurement precision
If a pawl and actuator mechanism is implemented for selective locking, then the control precision is improved, but the manufacturing cost increases
Solution Approach 1:
The pawl mechanism is designed to self-engage with the rack teeth through spring pressure, eliminating the need for complex actuation systems. The spring automatically pushes the pawl into engagement with the rack, providing precise locking control without requiring additional actuators or complex control mechanisms, thereby reducing manufacturing costs while maintaining control precision.
Data Source
AI summary
An adjustable steering column assembly for a vehicle having an outer jacket and an inner jacket slideably disposed within the outer jacket along a longitudinal axis for telescoping movement. A pivot pin is coupled to the outer jacket and defines a pin axis. A pawl is disposed about the pivot pin and is rotatable about the pin axis between and engaged position engaging the inner jacket for preventing the telescoping movement and a disengaged position disengaging the inner jacket for allowing the telescoping movement. An actuator is mounted to the pivot pin for concurrent rotation with the pivot pin about the pin axis and is coupled to the pawl for moving the pawl between the engaged and disengaged positions in an opposing rotational direction from the concurrent rotation of the pivot pin and the actuator.