Oldham Coupling Asymmetric Fitting for Phase Alignment
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Solution Overview
Problem
Oldham couplings used in synchronous electric motors can lead to erroneous rotational angular position detection due to the potential for one coupling part to be rotated by 180 degrees relative to the other, resulting in inappropriate phase supply of electric current to windings, necessitating additional adjustment processes.
Innovation Solution
Incorporating fitting indication portions on the coupling parts and intermediate part of the Oldham coupling, such as protrusions, recesses, or magnetic features, to ensure accurate positional relationship determination between the coupling parts about a rotational axis, preventing unintentional 180-degree rotation and facilitating precise phase alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fitting portions are made with symmetric shape extending through the center of the intermediate part, then the coupling parts can be mechanically fitted to each other with allowance for 180-degree rotation, but this causes erroneous rotational angular position detection by 180 degrees in synchronous electric motors
Solution Approach 1:
The patent applies asymmetry by providing fitting indication portions (protrusions or recesses) at specific angular positions on the coupling parts and intermediate part. These asymmetric features prevent 180-degree rotation by ensuring that the coupling parts can only be assembled in the correct angular orientation, where the fitting indication portions align properly. This resolves the contradiction by maintaining ease of assembly through simple mechanical fitting while eliminating erroneous position detection through asymmetric positioning features.
2Measurement precision
If additional processes are implemented to check and adjust phases of the electric motor and detector, then rotational angular position detection accuracy is improved, but the device complexity and manufacturing time increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring the fitting indication portions on the coupling parts and intermediate part during manufacturing. These asymmetric features are built into the structure beforehand, so that when assembly occurs, the correct angular alignment is automatically achieved without requiring subsequent phase checking or adjustment processes. This eliminates the need for additional complex adjustment steps while ensuring accurate rotational angular position detection.
3Device complexity
If the Oldham coupling is used in synchronous electric motors without fitting indication portions, then the structural simplicity is maintained, but phase alignment between the electric motor and detector cannot be ensured
Solution Approach 1:
The patent applies local quality by adding fitting indication portions only at specific critical locations on the coupling parts and intermediate part, rather than fundamentally changing the overall simple Oldham coupling structure. These localized asymmetric features (protrusions or recesses at specific angular positions) provide the necessary phase alignment functionality while maintaining the structural simplicity and ease of manufacture of the original Oldham coupling design.
Data Source
AI summary
An Oldham coupling includes a first coupling part, a second coupling part and an intermediate part. The first coupling part and the second coupling part are coupled to each other with the intermediate part provided therebetween. The first coupling part and the second coupling part are fitted on fitting portions of the intermediate part extending perpendicular to each other. The first coupling part, the second coupling part and the intermediate part have fitting indication portions. The fitting indication portions allow a positional relationship between the first coupling part and the second coupling part about a rotational axis to be determined.