Torque Sensor Radial Yoke Design for Axial Position Tolerance
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Solution Overview
Problem
Existing torque sensors in power steering systems face challenges in accurate torque detection due to variations in the relative axial direction position between the magnetic member and yoke members, leading to inconsistent output characteristics.
Innovation Solution
A torque sensor design featuring a magnetic member with alternately arranged magnetic poles, paired with first and second yoke members having concentrically arranged nail portions and ring portions, and a Hall device to detect changes in the magnetic field caused by torsion deformation, ensuring accurate torque detection regardless of the relative axial position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the nail portions of the first yoke member and the nail portions of the second yoke member are set at different axial direction positions, then the magnetic flux concentration is improved, but the output characteristics vary greatly when the relative axial direction position changes
Solution Approach 1:
The patent transitions from a one-dimensional axial arrangement to a two-dimensional radial arrangement by positioning the nail portions concentrically in the radial direction. This dimensional change allows the magnetic flux concentrators to effectively concentrate magnetic flux while maintaining consistent output characteristics regardless of axial position variations.
Solution Approach 2:
The patent changes the geometric parameters of the yoke members by introducing ring portions that connect the nail portions concentrically. This parameter modification creates a new structural configuration where the nail portions are arranged in the radial direction rather than axially, resolving the contradiction between flux concentration and output consistency.
2Adaptability or versatility
If the relative axial direction position between the magnetic member and the yoke members changes, then the assembly flexibility is improved, but the air gap variation causes inaccurate torque detection
Solution Approach 1:
By arranging the nail portions concentrically in the radial direction and connecting them with ring portions, the patent creates a structure that is insensitive to axial position changes. This radial configuration ensures that the air gap between the magnetic member and yoke members remains consistent even when axial positions vary, maintaining torque detection accuracy while allowing assembly flexibility.
Solution Approach 2:
The ring portions serve multiple functions: they connect the nail portions concentrically, maintain the radial arrangement geometry, and provide structural support. This multi-functional design allows the yoke members to accommodate axial position variations while maintaining consistent magnetic flux concentration and torque detection accuracy.
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
The solution enables precise torque detection and minimizes output variations, maintaining accuracy even with shifts in the relative axial position, thus enhancing the reliability of the power steering system.
Implementation Method 1
a magnetic sensor having a Hall device that detects a change of magnetic field between the first ring portion and the second ring portion
Implementation Method 2
a magnetic member provided at the first shaft member so as to rotate integrally with the first shaft member and having different magnetic poles that are alternately arranged in a circumferential direction
Data Source
AI summary
Torque sensor detects torque of steering shaft formed by first and second shafts which are connected through torsion bar. Torque sensor has: a magnetic member provided at the first shaft and having magnetic poles alternately arranged in circumferential direction concentrically with rotation axis; a first yoke member provided at the second shaft and having (a) first nail portions arranged concentrically with the rotation axis and facing the magnetic member in radial direction and (b) a first ring portion; a second yoke member provided at the second shaft and having (c) second nail portions arranged concentrically with the rotation axis so that the first and second nail portions are alternately arranged in the circumferential direction and the second nail portions face the magnetic member in the radial direction and (d) a second ring portion arranged to be separated from and face the first ring portion; and a magnetic sensor.