Steering Column Clamp Load Assembly With Cam Assist Locking
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Solution Overview
Problem
Existing manual rake and telescope column designs fail to provide simultaneous holding loads, face limitations in locking positions, and require excessive lever effort or wear due to inadequate clamp mechanisms.
Innovation Solution
A lever assembly with a rotatable lock lever, a bolt, and a clamp load assembly featuring an assist cam, follower, and a linear assist spring, which provides increased clamp load without increasing lever effort by tuning assist torque and maintaining ergonomic feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the clamp mechanism is set tighter at assembly to increase friction, then the clamp load is increased, but the lever effort is exceeded or wear is observed in the clamp mechanism
Solution Approach 1:
The clamp load assembly transitions from a static pre-set friction mechanism to a dynamic system where the cam profile actively modulates the normal force applied by the clamp mechanism during lever rotation, allowing the clamp load to vary optimally throughout the locking cycle rather than remaining constant
Solution Approach 2:
The cam profile changes the geometric parameters of the clamp mechanism during operation, converting rotational lever motion into varied normal force application on the clamp surfaces, thereby optimizing both clamp load and lever effort throughout the locking sequence
2Force
If a torsion spring is used to provide torsional assist, then the clamp mechanism can be set higher without increasing lever locking load, but packaging space is required and tuning and timing of the assist is limited
Solution Approach 1:
The solution transitions from a torsional spring providing assist in the rotational dimension to a cam profile that provides assist through axial dimension changes, converting the spring's rotational assist into linear axial motion that drives the clamp mechanism, thereby reducing packaging space requirements
Solution Approach 2:
The torsion spring mechanism is replaced with a cam-profile-based mechanical system that achieves the same assist function through geometric transformation rather than elastic storage, eliminating the need for spring packaging space while maintaining the assist function
3Reliability
If saw teeth are used to engage when the lever is locked, then positive lock is achieved, but the same device cannot provide both rake and telescope holding load and there are multiple positions where the lever cannot be locked
Solution Approach 1:
The cam profile-based clamp load assembly serves multiple functions simultaneously: it provides positive locking through cam follower engagement, maintains holding load through continuous normal force application, and enables locking at any lever position through its geometric design, replacing the need for separate mechanisms for different functions
Solution Approach 2:
The system transitions from static saw tooth engagement at fixed positions to dynamic cam profile engagement that adapts to any lever position, allowing the clamp mechanism to provide positive lock and holding load regardless of the specific rake or telescope angle
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 achieves higher clamp loads for both rake and telescope adjustments, ensures locking in any position, reduces lever effort, and eliminates 'lever slap' through optimized assist timing and packaging efficiency.
Implementation Method 1
an assist spring biased the assist follower onto the assist cam
Implementation Method 2
an assist cam having a cam profile defined by at least one ramp. The clamp load assembly also includes an assist follower having a follower profile in contact with the cam profile
Data Source
AI summary
A lever assembly for a steering column includes a rotatable lock lever. The lever assembly also includes a bolt operatively coupled to the rotatable lock lever and rotated therewith. The lever assembly further includes a clamp load assembly operatively coupled to the bolt. The clamp load assembly includes an assist cam having a cam profile defined by at least one ramp. The clamp load assembly also includes an assist follower having a follower profile in contact with the cam profile. The clamp load assembly further includes an assist spring disposed between the assist follower and a column structure, the assist spring biasing the assist follower into contact with the assist cam.