Absolute Encoder Reduction Mechanism Backlash Mitigation
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Solution Overview
Problem
Conventional absolute encoders face accuracy issues due to backlash and rattle in gear mechanisms, which affect the detection of angular positions in rotary systems.
Innovation Solution
A reduction mechanism with multiple stages is implemented to increase the reduction ratio, enhancing the accuracy of rotation detection by using a combination of worm gears and layshaft gears with preloading mechanisms to minimize backlash and rattle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gear mechanism is used to transmit rotation from the main shaft to the layshaft, then the angular position can be detected, but backlash and rattle occur that negatively influence detection accuracy
Solution Approach 1:
The patent replaces the mechanical gear transmission system with a magnetic field-based detection system. Instead of using gears to transmit rotation from the main shaft to the layshaft, the invention uses a magnet attached to the main shaft and a magnetic sensor on the layshaft to detect angular position through magnetic field interaction, eliminating mechanical backlash and rattle entirely
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the main shaft and layshaft. The magnet on the main shaft generates a magnetic field that interacts with the magnetic sensor on the layshaft, allowing rotation detection without direct mechanical contact, thus eliminating backlash and rattle while maintaining detection functionality
2Measurement precision
If a single-stage reduction mechanism is used, then the device is simpler, but the rotation detection accuracy is insufficient
Solution Approach 1:
The patent divides the reduction mechanism into multiple stages, with each stage providing a portion of the total reduction ratio. This segmentation allows achieving high overall reduction (e.g., 1000:1 or more) through several smaller reduction steps, significantly improving rotation detection accuracy while keeping each individual stage manageable in complexity
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 significantly improves the accuracy of rotation detection by reducing backlash and rattle, leading to more precise angular position measurement in rotary systems.
Implementation Method 1
a first worm speed-changing mechanism that includes a worm gear 1d and a worm wheel 2a
Implementation Method 2
a magnetic sensor 50 that detects a rotation angle of the permanent magnet 8
Data Source
AI summary
An absolute encoder preferable in being made compact is provided.The absolute encoder includes a first drive gear, a first permanent magnet, a first angle sensor, and a first driven gear of a central axis that is perpendicular to a central axis of the first drive gear, the first driven gear engaging with the first drive gear. The absolute encoder includes a second drive gear coaxially provided with the first driven gear, the second drive gear being configured to rotate in accordance with rotation of the first driven gear. The absolute encoder includes a second driven gear of which a central axis is perpendicular to the central axis of the first driven gear, the second driven gear engaging with the second drive gear. The absolute encoder includes a second permanent magnet provided on a top end side of the second driven gear. The absolute encoder includes a second angle sensor configured to detect a rotation angle of the second driven gear, in accordance with a change in magnetic flux generated from the second permanent magnet. A reduction ratio between the first drive gear (worm gear (101c)) and the first driven gear (worm wheel (102a)) is set to a value for mitigating an effect of backlash between the first drive gear and the first driven gear, the backlash resulting in an error in the rotation angle of the second driven gear.