Rotational Angle Measurement Device Using Magnetic Coupling
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Solution Overview
Problem
Current methods for measuring the rotation angle of a rotating moving shaft in machine tools, such as those using Hirth couplings and rotary encoders, face challenges including prolonged measurement time, limited accuracy due to transmission errors, and errors caused by initial offset and eccentricity, which complicate precise installation and lead to decreased measurement accuracy.
Innovation Solution
A rotation angle measurement device that incorporates relative angle detection means with a reference support and non-contact angle detection means, allowing for accurate detection of the rotation angle without physical contact, and includes correction mechanisms to address periodic interpolation errors and initial offset errors, thereby improving measurement accuracy and simplifying installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Hirth coupling is used to measure rotation angle, then the measurement can be performed with gear-based indexing, but the measurement time is prolonged due to oscillating motions and transmission errors occur
Solution Approach 1:
The patent replaces the mechanical Hirth coupling system with a magnetic coupling system. The magnetic coupling eliminates the need for mechanical gear engagement and oscillating motions, allowing continuous rotation measurement without the time-consuming back-and-forth indexing movements required by mechanical systems.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the rotating shaft and the measurement system. This magnetic intermediary allows non-contact transmission of rotational information, eliminating mechanical transmission errors and the need for physical gear engagement.
2Measurement precision
If a rotary encoder is used to measure rotation angle, then high accuracy can be achieved by increasing graduation resolution, but initial offset errors and eccentricity errors occur due to installation complexity
Solution Approach 1:
The patent creates a virtual copy of the rotational position information through magnetic field detection. Instead of requiring precise physical alignment of encoder components, the magnetic coupling system captures rotational data through field interaction, eliminating the need for meticulous installation alignment.
Solution Approach 2:
The magnetic field serves as an intermediary that decouples the measurement system from the rotating shaft, eliminating the need for direct mechanical connection and the associated installation precision requirements.
3Measurement precision
If the number of faces of a polygon mirror is increased to achieve finer angle measurement, then measurement resolution improves, but the cost of the polygon mirror increases
Solution Approach 1:
The patent replaces the polygon mirror optical system with a magnetic coupling system. This substitution eliminates the need for expensive multi-faceted mirrors while achieving continuous high-resolution angle measurement through magnetic field detection.
Solution Approach 2:
The patent changes the measurement parameter from optical reflection angles (requiring multiple mirror faces) to magnetic field orientation, allowing continuous measurement resolution without increasing the physical complexity or cost of the sensing component.
Data Source
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AI summary
A rotation angle measurement device includes: relative angle detection means 12 including a reference support 26 whose rotation is regulated in a fixed range in an arbitrary direction of a rotation axis, and a driving rotating body 22 which is coupled to the reference support 26 and is axially supported so as to be all-round rotatable with respect to the reference support 26, the relative angle detection means 12 which detects a relative rotation angle of the rotating body 22 with respect to the reference support 26; and non-contact angle detection means 40 which detects a rotation angle of the reference support 26 with reference to a position that does not contact with the rotating body 22 and the reference support 26. This provides improved accuracy in indexing the rotation angle of a rotating moving shaft and easy installation onto the rotating moving shaft.