Steering Apparatus Cam Mechanism Reduces Lever Operating Force
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Solution Overview
Problem
Conventional steering apparatuses with cam mechanisms face challenges in reducing lever operation load while maintaining operability, often resulting in high operating forces and quick return of the operating lever during locking and unlocking operations.
Innovation Solution
The steering apparatus incorporates a primary and secondary cam with inclined surface portions, featuring a low gradually inclined surface, a middle sharply inclined surface, and a high gradually inclined surface, arranged in a specific order to reduce the operating force and prevent quick return of the lever, by allowing smooth transitions and controlled movements during locking and unlocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a cam surface with a single inclined line is used, then the structure is simple, but the operating force of the operating lever is large in the rear region of the stroke
Solution Approach 1:
The cam surface is divided into multiple inclined portions (first, second, and third inclined portions) with different inclination angles. Each portion corresponds to a different region of the operating lever stroke, allowing the operating force to be optimized for each specific region rather than using a single uniform inclination angle throughout.
Solution Approach 2:
Different regions of the cam surface are given different local properties through varying inclination angles. The first inclined portion has a larger inclination angle for the front region, the second inclined portion has a smaller inclination angle for the rear region where operating torque tends to be large, and the third inclined portion has a medium inclination angle for the intermediate region.
2Force
If the inclination angle of the cam surface is reduced in the rear region of the stroke, then the operating force is reduced, but the operation angle of the operating lever increases
Solution Approach 1:
The cam surface is segmented into multiple inclined portions, each optimized for a specific region of the operating lever stroke. This allows the rear region to have a smaller inclination angle for reduced operating force while the front and intermediate regions maintain appropriate inclination angles to control the overall operation angle.
Solution Approach 2:
The inclination angle parameter of the cam surface is changed across different regions rather than maintaining a constant value. By varying this parameter (larger angle in front region, smaller angle in rear region, medium angle in intermediate region), the patent achieves reduced operating force in critical areas without proportionally increasing the total operation angle.
3Force
If multiple inclined portions with different inclination angles are provided on the cam surface, then the operating force is reduced in specific regions, but the cam surface structure becomes more complex
Solution Approach 1:
The cam surface is divided into three distinct inclined portions, each with a specific inclination angle optimized for its corresponding region of the operating lever stroke. This segmentation allows targeted optimization of operating force in different regions while maintaining a systematic and organized structure.
Solution Approach 2:
Each region of the cam surface is given a specific local quality (inclination angle) appropriate for its function. The first inclined portion has a larger angle for the front region, the second has a smaller angle for the rear region where operating torque is naturally larger, and the third has a medium angle for the intermediate region, creating a balanced overall structure.
4Speed
If the cam follower moves quickly from the second inclined portion to the first inclined portion during unlocking, then the unlocking speed is fast, but the operating lever returns extremely quickly causing poor operability
Solution Approach 1:
The transition path from the second inclined portion to the first inclined portion is segmented by introducing the third inclined portion with a medium inclination angle. This intermediate portion acts as a buffer zone that slows down the cam follower's movement during the transition, preventing the operating lever from returning too quickly while still maintaining efficient unlocking performance.
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 enhances the operation feeling and reduces the lever operation load without increasing the operation angle, providing improved operability and ensuring complete fastening is realized by the operator.
Implementation Method 1
Japanese Patent Application Laid-open No. 2002-59851 discloses a steering apparatus equipped with a cam mechanism
Implementation Method 2
the cam surface 28 includes a first inclined portion 29 having a relatively large inclination angle and a second inclined portion 30 having a relatively small inclination angle
Data Source
AI summary
A steering apparatus includes a fixed bracket, a fastener, a primary cam that rotates with a rotation operation of the fastener, and a secondary cam that is non-rotatably attached to a fixed side portion and is in contact with the primary cam. Cam operating portions each including an inclined surface portion, a high level surface, and a contact protrusion are formed at regular intervals along a circumferential direction on a base flat surface of each of the primary cam and the secondary cam, and the inclined surface portion is constituted by a low gradually inclined surface, a middle sharply inclined surface, and a high gradually inclined surface arranged in this order from the base flat surface toward the high level surface.