Absolute Encoder Worm Gear Thermal Expansion Backlash
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Solution Overview
Problem
Absolute encoders face reliability issues in high-temperature environments due to thermal expansion, which can lead to backlash and reduced detection accuracy, especially when motor speed increases, necessitating a solution to maintain precision and reliability.
Innovation Solution
The absolute encoder design incorporates a first drive gear and a first driven gear made of different materials, with a specific configuration of worm gears and layshaft gears, along with a leaf spring for preloading, to reduce backlash and enhance reliability by managing thermal expansion and increasing the distance between permanent magnets to minimize magnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gears are made of the same material, then manufacturing is simpler, but thermal expansion causes backlash and reduces detection accuracy in high-temperature environments
Solution Approach 1:
The drive gear is made of a first material and the driven gear is made of a second material different from the first material. This composite material approach allows different thermal expansion characteristics between mating gears, preventing backlash elimination due to thermal expansion in high-temperature environments while maintaining manufacturing feasibility.
2Productivity
If motor rotation speed is increased, then productivity improves, but detection accuracy decreases due to gear engagement issues
Solution Approach 1:
By using different materials for drive and driven gears, the invention reduces backlash and improves meshing stability at high speeds, thereby maintaining detection accuracy even when motor rotation speed is increased for higher productivity.
Solution Approach 2:
The invention changes material parameters (selecting different materials with appropriate thermal and mechanical properties) to optimize gear performance at high rotation speeds, preventing detection accuracy degradation while maintaining high productivity.
3Volume of moving object
If permanent magnets are placed closer together, then device size is reduced, but magnetic interference increases
Solution Approach 1:
A magnetic shielding plate is introduced as an intermediary element between permanent magnets to block magnetic flux interference. This allows the permanent magnets to be positioned closer together, reducing encoder size, while the shielding plate prevents harmful magnetic interference between them.
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
This configuration effectively prevents backlash and tooth clogging in high-temperature environments, maintains detection accuracy at increased motor speeds, and extends the life of the encoder by reducing wear and adhesion between gears.
Implementation Method 1
When the absolute encoder described in Patent Document 1 operates in a poor environment such as a high-temperature environment, backlash may be eliminated due to thermal expansion
Implementation Method 2
a magnetic sensor that detects a rotation angle based on magnetic flux that is generated through the permanent magnet
Data Source
AI summary
An absolute encoder preferable in being made compact is provided.The absolute encoder includes a worm gear (101c) that rotates in accordance with rotation of a main spindle, and a worm wheel (102a) of which a central axis is perpendicular to a central axis of the worm gear (101c), the worm wheel engaging with the worm gear (101c). The worm gear (101c) is formed using a first material, and the worm wheel (102a) is formed using a second material different from the first material.