Steering Wheel Vibration Reduction via Segmented Elastic Support
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Solution Overview
Problem
Conventional steering wheel designs face challenges in achieving a balance between effective vibration reduction and horn switch operability due to the conflicting requirements of spring constants for the dynamic damper and horn switch, leading to potential malfunctions.
Innovation Solution
A vibration reducing structure for the steering wheel is proposed, utilizing a mass supported by both a first elastic body for axial movement and a second elastic body for perpendicular movement, allowing the mass to function as a dynamic damper without affecting the horn switch's operation, with the second elastic body having different spring constants in up-and-down and lateral directions to tune vibration absorption characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common coil spring is used for both horn switch and dynamic damper, then the device complexity is reduced, but the horn switch may malfunction due to vibration or the dynamic damper cannot effectively fulfill its function
Solution Approach 1:
The patent divides the single coil spring into two separate elastic bodies: a first elastic body (coil spring) for supporting the horn switch in the axial direction, and a second elastic body for supporting the mass in the radial direction. This segmentation allows each elastic body to be independently optimized for its specific function, preventing vibration from affecting the horn switch while enabling effective vibration reduction through the dynamic damper.
Solution Approach 2:
The patent extracts the radial vibration support function from the axial coil spring and assigns it to a separate second elastic body. This extraction resolves the conflict between the axial stiffness requirements for the horn switch and the radial stiffness requirements for the dynamic damper, as each elastic body can now have independently optimized spring constants.
2Reliability
If a stiffer coil spring is employed to prevent horn switch malfunction, then the horn switch operability is improved, but the spring constant in the perpendicular direction becomes higher than needed for effective dynamic damper function
Solution Approach 1:
The patent applies local quality by giving different stiffness characteristics to different parts of the support system. The first elastic body has high axial stiffness to ensure reliable horn switch operation, while the second elastic body has optimized radial stiffness to effectively reduce vibrations. Each elastic body is locally optimized for its specific directional requirement rather than using a uniform spring constant in all directions.
3Object-affected harmful factors
If a soft coil spring is employed to allow dynamic damper function, then the spring constant in the perpendicular direction is reduced, but the horn switch may malfunction due to vibration
Solution Approach 1:
By segmenting the support system into two separate elastic bodies with independent spring constants, the patent allows the second elastic body to be optimized for vibration reduction with lower radial stiffness, while the first elastic body maintains high axial stiffness to prevent horn switch malfunction. This segmentation eliminates the trade-off that exists when using a single coil spring for 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
This configuration effectively reduces steering wheel vibrations in the perpendicular direction while maintaining the operability of the horn switch, allowing for independent tuning of vibration absorption characteristics and reducing the number of components, weight, and cost by using an air bag module as the dynamic damper.
Implementation Method 1
a slider is supported on a fixed portion of the steering wheel via the first elastic body so as to be movable in the direction of the axis
Implementation Method 2
the mass is supported on the slider via the second elastic body so as to be movable in the direction perpendicular to the axis
Implementation Method 3
the mass is allowed to vibrate in the direction perpendicular to the axis so as to function as a dynamic damper
Data Source
AI summary
A slider 24 is supported on a holder 19 of a steering wheel 11 via a coil spring 25 so as to be movable in a direction of an axis while an air bag module 20 is supported on a slider 24 via a damper spring 26 so as to be movable in a direction perpendicular to the axis. Since the coil spring 25 does not affect vibration of the air bag module 20 in the direction perpendicular to the axis, it is possible to set a spring constant of the coil spring 25 at a value appropriate for the operation of a horn switch 37, and to set a spring constant of the damper spring 26 at a value appropriate for the operation of the dynamic damper. As a result, it is possible to effectively reduce the vibration of the steering wheel 11 in the direction perpendicular to the axis with the dynamic damper without affecting the operability of the horn switch 37.