Steering Column Locking Mechanism Reducing Handle Rotation Force
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Solution Overview
Problem
Existing adjustable steering column assemblies require excessive force to rotate the handle for simultaneous telescoping and raking movements, and during collisions, the inner jacket slides within the outer jacket, compromising safety.
Innovation Solution
An adjustable steering column assembly with a locking device featuring a pivot pin, pawl, lever, and extension that reduces the force needed to rotate the handle and prevents the inner jacket from sliding within the outer jacket by using a cam surface mechanism to disengage the pawl from the inner jacket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking device is used to prevent telescoping movement, then safety is improved, but the force required to rotate the handle increases
Solution Approach 1:
The locking device is segmented into multiple independent components: a first locking mechanism with a first pawl and first locking surface for telescoping movement, and a second locking mechanism with a second pawl and second locking surface for raking movement. This segmentation allows the mechanisms to operate independently, reducing the force required to rotate the handle while maintaining safety through multiple locking points.
Solution Approach 2:
A cam mechanism acts as an intermediary between the handle rotation and the pawl disengagement. The cam surface converts rotational motion into the necessary force to disengage the pawls from their locking surfaces, reducing the direct force requirement on the handle while maintaining effective locking during normal operation.
2Reliability
If a locking device prevents telescoping movement, then safety is improved, but the complexity of the device increases
Solution Approach 1:
The first and second locking mechanisms are merged into a single integrated locking device that operates through one handle rotation. The shared cam mechanism simultaneously controls both pawls, reducing overall device complexity while maintaining dual-function safety locking for both telescoping and raking movements.
Solution Approach 2:
The locking device is designed with multi-functionality, where a single handle rotation controls both the first pawl for telescoping movement and the second pawl for raking movement. This universal design reduces the number of separate mechanisms needed while maintaining comprehensive safety coverage.
3Ease of operation
If the inner jacket is allowed to slide in the outer jacket for adjustment, then ease of operation is improved, but safety during collision deteriorates
Solution Approach 1:
The locking mechanism transitions between dynamic states: during normal operation, the first and second pawls are disengaged, allowing free telescoping and raking movement for ease of adjustment. During collision, the cam mechanism engages the pawls with the locking surfaces, providing dynamic safety locking that activates only when needed.
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 reduces the force required to adjust the steering wheel position and prevents the inner jacket from sliding during collisions, enhancing user comfort and safety by allowing easier handle rotation and maintaining the jacket's position.
Implementation Method 1
The locking device further includes a lever coupled to the pawl with the lever having a cam surface. The extension movable between a first position engaging a first portion of the cam surface and a second position engaging a second portion of the cam surface for moving the lever away from the inner jacket and causing the pawl to rotate about the pin axis to disengage the pawl from the inner jacket.
Data Source
AI summary
An adjustable steering column assembly having an outer jacket and an inner jacket slidably disposed in the outer jacket for telescoping movement is disclosed. The assembly includes a locking device having a pivot pin coupled to the outer jacket and defining a pin axis. A pawl is coupled to the pivot pin and a lever having a cam surface is coupled to the pawl. The pawl rotates about the pin axis between an engaged position engaging the inner jacket and a disengaged position disengaging the inner jacket for preventing and allowing the telescoping movement, respectively. An extension is movable between a first position engaging a first portion of the cam surface and a second position engaging a second portion of the cam surface for moving the lever away from the inner jacket and causing the pawl to rotate about the pin axis to disengage the pawl from the inner jacket.