Rotation Angle Detection Device Using Differential Gear Speeds
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Solution Overview
Problem
Conventional rotation angle detection devices require a large installation space, which poses challenges for mounting on vehicles and are costly due to the arrangement of gears around the shaft's periphery.
Innovation Solution
A rotation angle detection device with a reduced installation space, utilizing a target that rotates in unison with the shaft, a rotating member with a different speed, a first sensor with a changing output signal, and a computing section to calculate the absolute angle based on the output signal and rotation angle of the rotating member, where the output signal changes at a different period than the rotation period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gears are arranged around the outer periphery of the shaft to detect absolute angle over multiple revolutions, then the detection capability is improved, but the installation space increases
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of gears around the shaft periphery to a three-dimensional configuration where gears are positioned within the shaft's cross-sectional area. This dimensional change allows the detection mechanism to be compacted inward rather than extending outward, significantly reducing the radial installation space while preserving the multi-revolution absolute angle detection capability through the same gear ratio principles.
2Measurement precision
If multiple gears with different pitch circle diameters and tooth counts are used to detect multi-rotation angle, then the detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple detection functions into a single integrated gear-magnet assembly. Instead of using separate gears and magnets for each detection point, the invention uses one gear with multiple magnets attached at different radial positions, where each magnet interacts with corresponding sensors. This merging reduces the number of discrete components while maintaining the ability to detect absolute angles over multiple revolutions through the differential rotation speeds of the gear components.
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 reduces the installation space and cost of the rotation angle detection device while maintaining effective detection capabilities, allowing for precise calculation of the absolute angle of the shaft over multiple revolutions.
Implementation Method 1
a first sensor whose output signal changes when the target is approached
Implementation Method 2
a second sensor that detects a rotation angle of the rotating member within one rotation
Data Source
AI summary
A rotation angle detection device includes at least one target rotating in unison with a shaft, a rotating member for rotating at a different rotation speed from the shaft as the shaft rotates, a first sensor whose output signal changes when the target is approached, a second sensor that detects the rotation angle of the rotating member within one rotation, and a computing section that calculates the absolute angle of the shaft based on the output signal of the first sensor and the rotation angle of the rotating member detected by the second sensor. The output signal of the first sensor changes at a period different from the rotation period of the rotating member when the shaft rotates, and the computing section detects the absolute angle of the shaft at that time from the rotation angle of the rotating member when the output signal of the first sensor changes.