Steering Angle Sensor Intermediate Gear Roundness Error Compensation
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Solution Overview
Problem
Conventional steering angle sensors face challenges in ensuring high roundness of the annular drive gear, leading to errors in angle-of-rotation information due to molding characteristics like sink marks and shrinkage, which are exacerbated by the complex shape and large openings required for the steering shaft, causing discrepancies in the rotation angles of the driven gears.
Innovation Solution
The introduction of an intermediate gear that meshes with the annular drive gear and the driven gears, allowing for higher roundness and reduced error in angle-of-rotation information, achieved by supporting the intermediate gear on the annular drive gear and driven gears without the need for large openings or engagement portions, and using a resin or metal material to minimize molding defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the annular drive gear is molded using resin material with a complex shape and large openings for the steering shaft, then the ease of manufacture is improved, but the manufacturing precision deteriorates due to sink marks and shrinkage
Solution Approach 1:
An intermediate gear is introduced between the annular drive gear and the driven gears. This intermediate gear serves as a mediator that receives rotation from the annular drive gear and transmits it to the driven gears. The intermediate gear is designed with a simple circular shape without large openings, allowing it to be molded with high roundness using resin material, thereby compensating for the poor roundness of the annular drive gear.
2Ease of manufacture
If the annular drive gear has low roundness due to molding characteristics, then the ease of manufacture is improved, but the measurement precision deteriorates in angle-of-rotation information
Solution Approach 1:
The intermediate gear acts as a precision transmission element that isolates the measurement system from the low-roundness annular drive gear. By meshing with both the annular drive gear and the driven gears, it filters out roundness errors and provides accurate rotational transmission, ensuring high precision in angle-of-rotation information despite the poor roundness of the drive gear.
3Adaptability or versatility
If the annular drive gear has a complex shape with large openings and engagement portions, then the adaptability is improved for steering shaft insertion, but the manufacturing precision deteriorates due to molding defects
Solution Approach 1:
The gear transmission system is segmented into three independent components: the annular drive gear (optimized for steering shaft insertion with its complex shape and large openings), the intermediate gear (optimized for high roundness with its simple circular shape), and the driven gears (optimized for angle detection). This segmentation allows each component to be optimized for its specific function without compromising the others.
Solution Approach 2:
The intermediate gear serves as a mediator that decouples the functional requirements of the annular drive gear (adaptability for steering shaft) from the precision requirements of the angle measurement system. Its simple circular geometry enables high manufacturing precision while still transmitting rotation accurately from the complex-shaped drive gear.
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 precision of angle-of-rotation information generation by reducing errors caused by gear roundness, maintaining accurate computation without altering processing content, and allowing for a more compact and robust sensor design.
Implementation Method 1
the intermediate gear that meshes with the annular drive gear, the first driven gear, and the second driven gear is interposed between the annular drive gear and the first driven gear and the second driven gear
Implementation Method 2
Magnets 104 and 106 are integrally disposed in the first driven gear 103 and the second driven gear 105, respectively
Implementation Method 3
elements 111 and 113 that detect changes in magnetic fields based on the rotation of the magnets 104 and 106 are mounted on the circuit board 110
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
There is provided a steering angle sensor in which the effect of errors in angles of rotation arising in a first driven gear and a second driven gear because of the roundness of an annular drive gear is reduced and which can generate angle-of-rotation information of a steering wheel with good precision. A steering angle sensor is equipped with an annular drive gear, which rotates in accompaniment with the rotation of a steering wheel, and a first driven gear and a second driven gear, which have magnets disposed in them and rotate in a driven manner in accordance with the rotation of the annular drive gear, the steering angle sensor being for generating angle-of-rotation information of the steering wheel utilizing changes in magnetic fields based on the rotation of the first driven gear and the second driven gear, wherein an intermediate gear that meshes with the annular drive gear, the first driven gear, and the second driven gear is interposed between the annular drive gear and the first driven gear and the second driven gear.