Variable Gear Ratio Rack Bar Segmentation for Steering Precision
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Solution Overview
Problem
Conventional variable gear ratio steering systems face challenges in processing rack-formed parts with different inter-tooth spaces efficiently, leading to precision issues and increased manufacturing costs due to the need for multiple steps and separate molds.
Innovation Solution
A variable gear ratio type rack bar with two or more rack-formed parts having different inter-tooth spaces, where at least one part is formed separately and coupled to the rack bar body, allowing for continuous arrangement and precise tooth shape formation through various processing methods without requiring a separate mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rack-formed parts with different inter-tooth spaces are processed using conventional methods, then multiple separate molds and processing steps are required, but this increases manufacturing complexity and costs
Solution Approach 1:
The rack bar is divided into multiple rack-formed parts (first rack-formed part, second rack-formed part, etc.) with different inter-tooth spaces, where each part can be processed independently using the same mold. This segmentation allows different sections of the rack bar to have different gear ratios while using a single processing tool, thereby reducing mold complexity and processing steps.
2Force
If variable gear ratio is implemented by increasing hydraulic pressure or motor power, then torque applied to pinion is reduced, but this creates inefficiency and limitations
Solution Approach 1:
Different sections of the rack bar are given different inter-tooth spaces to create local variations in gear ratio. The first rack-formed part has a first inter-tooth space while the second rack-formed part has a second inter-tooth space different from the first. This allows the steering system to optimize torque distribution locally without requiring increased hydraulic pressure or motor power, thereby maintaining overall system efficiency.
3Ease of operation
If constant gear ratio is used in rack and pinion, then steering apparatus is simple, but this causes inconvenience during parking or U-turning when large steering angle is required
Solution Approach 1:
The rack bar transitions from a constant gear ratio design to a variable gear ratio design where the inter-tooth space varies along the length of the rack bar. This dynamic variation in gear ratio allows the steering system to adapt to different operating conditions: using one gear ratio for normal steering and another for large-angle maneuvers like parking or U-turns, thereby improving ease of operation without excessive complexity.
Data Source
AI summary
Disclosed are a variable gear ratio type rack bar, and a steering apparatus having the same. According to the present invention, it is not required to fabricate a separate mold for processing rack-formed parts with different inter-tooth spaces, the rack-formed parts can be formed by using various processing methods, and it is possible to obtain precise tooth shapes through one step processing, whereby the number of steps for manufacturing a variable gear ratio type rack bar and its manufacturing cost can be reduced.