Steering Apparatus With Arm Stopper And Worm Damper
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Solution Overview
Problem
The existing motor-driven power steering apparatuses for ATV's face issues with excessive bending loads on the output shaft due to the arm stopper mechanism's design, leading to increased loads on bearings and housing, and inadequate backlash between worm and worm wheel, resulting in poor handling and noise.
Innovation Solution
The proposed steering apparatus features a modified arm stopper mechanism where the angle between the stopper's contact surfaces is greater than the steering arm's striking surfaces, allowing the input and striking load vectors to cancel each other, reducing bending loads, and incorporates a worm damper for adjustable backlash between worm and worm wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the arm stopper mechanism is configured with contact surfaces at 90 degrees to restrict steering arm turning angle, then the steering angle is effectively limited to prevent vehicle rollover, but a large bending load is applied to the output shaft due to the angle between input load vector and striking load vector
Solution Approach 1:
The patent changes the geometric parameter of the stopper contact surfaces from 90 degrees to an obtuse angle (greater than 90 degrees). This parameter change modifies the direction of the striking load vector, increasing the angle between the input load vector and striking load vector, thereby reducing the bending load on the output shaft while maintaining the steering angle restriction function.
Solution Approach 2:
Instead of making the contact surfaces perpendicular (90 degrees) to the steering arm, the patent inverts the approach by making them obtuse angles, which fundamentally changes the load vector direction and reduces the harmful bending component on the output shaft.
2Manufacturing precision
If the worm and worm wheel are fixed with rigid mounting to ensure precise meshing, then positioning accuracy is improved, but backlash cannot be adjusted leading to poor handling and noise
Solution Approach 1:
The patent introduces a damper component that allows the worm to move axially dynamically. This transforms the rigid fixed mounting into a dynamic system where the worm can adjust its position through axial movement, enabling backlash adjustment while maintaining precise meshing, thus improving handlebar controllability and reducing noise.
Solution Approach 2:
The damper acts as an intermediary component between the worm and its mounting structure. It mediates the position adjustment of the worm through axial movement, allowing controlled backlash variation while maintaining engagement with the worm wheel, thereby resolving the contradiction between fixed precision and adjustable controllability.
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 reduces bending loads on the output shaft, decreases loads on bearings and housing, improves handlebar controllability, and minimizes noise by allowing the worm to move axially, maintaining appropriate backlash.
Implementation Method 1
a ring-shaped elastic body 730 that can be elastically deformed
Data Source
AI summary
A steering apparatus includes: an output shaft that outputs a steering force to wheels of a vehicle; a steering arm which turns about the output shaft, and to which two tie rods, to which the wheels are respectively connected, are attached; a stopper which is provided in a vicinity of the output shaft, and restricts an angle of the turning of the steering arm; a worm wheel that is fixed to the output shaft; a worm that is driven by a motor, and meshes with the worm wheel; a bearing that rotatably support the worm; a housing that holds the bearing; and a worm damper that is provided at an axial inner side or an axial outer side of the bearing in an axial direction of the worm, and is elastically deformable so as to move the worm in the axial direction, as defined herein.