Relative Angle Detection Device Torque Range Expansion
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Solution Overview
Problem
Conventional torque detection systems, such as those using multipolar ring magnets and magnetic sensors, are limited to a linear portion of the helix angle, restricting the usable torque detection range and accuracy.
Innovation Solution
A relative angle detection device comprising multipolar ring magnets with alternately distributed magnetic poles and rotation angle sensors that calculate sin and cos signals, allowing for the calculation of relative angles and torque values beyond the linear portion through arctan(sin Δθ/cos Δθ), expanding the torque detection range and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only sin Δθ (square value addition value Z) is calculated and a linear portion thereof is used as a torque value, then the calculation is simple, but the torque detection range is limited to the linear portion
Solution Approach 1:
The patent changes the calculation parameter from only sin Δθ to both sin Δθ and cos Δθ, enabling the use of arctan function to calculate the actual helix angle Δθ. This parameter change allows the torque detection to extend beyond the limited linear portion of sin Δθ to the full range of the arctan function, resolving the contradiction between calculation simplicity and detection range.
2Adaptability or versatility
If the helix angle region exceeds the linear portion of sin Δθ, then more torque range is covered, but the helix angle cannot be uniquely calculated
Solution Approach 1:
The patent combines two calculation methods into a composite approach: using sin Δθ for calculations and cos Δθ for quadrant determination. This composite method ensures unique helix angle calculation across the full torque detection range by resolving the ambiguity that occurs when using sin Δθ alone beyond the linear portion.
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
Enables wider torque detection ranges and more accurate torque calculations by utilizing the full range of sin Δθ information, improving the resolution and accuracy of detected torque values.
Implementation Method 1
a first rotation angle sensor configured to detect a magnetic flux in accordance with a rotation angle θ1 of the first multipolar ring magnet and output the first sin signal representing sin θ1 and the first cos signal representing cos θ1
Data Source
AI summary
There are provided a relative angle detection device suitable for expanding a torque detection range, and a torque sensor, an electric power steering device and a vehicle including the relative angle detection device. Based on a first sine signal representing sin(θos+Δθ) and a first cosine signal representing cos(θos+Δθ) in accordance with a rotation angle(θis) of a first multipolar ring magnet that synchronously rotates with an input shaft from between the coaxially arranged input shaft and an output shaft, and based on a second sine signal representing sin θos and a second cosine signal representing cos θos in accordance with a rotation angle(θos) of a second multipolar ring magnet that synchronously rotates with the output shaft, sin Δθ and cos Δθ are calculated in accordance with a relative angle(Δθ) between the input shaft and the output shaft, and from Δθ=arctan(sin Δθ/cos Δθ), the relative angle(Δθ) is calculated.