Oldham Coupling Encoder Mounting for Axial Displacement
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Solution Overview
Problem
Existing rotating electric machines with leaf spring couplings face challenges in axial displacement absorption, particularly with large-diameter shafts and significant dimensional tolerances, leading to potential axial displacement exceeding the allowed amount by the coupling, which can affect the accuracy of rotation detection.
Innovation Solution
The implementation of an Oldham coupling that allows relative displacement in a direction intersecting the axial direction, combined with a washer for establishing concentricity between the rotation input pin and the shaft, facilitates easy attachment and detachment of the encoder while maintaining accurate rotation detection, even with large shaft diameters and varying axial positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a leaf spring coupling is used to absorb axial displacement between the shaft and rotation input pin, then axial displacement can be absorbed, but the axial displacement may exceed the allowed amount particularly with large-diameter shafts and significant dimensional tolerances
Solution Approach 1:
The patent introduces an Oldham coupling as an intermediary mechanism between the shaft and rotation input pin. This coupling includes two hubs connected by perpendicular arms that allow axial displacement while maintaining rotational synchronization. The intermediary structure absorbs axial movement without compromising the accuracy of rotation detection, resolving the contradiction between adaptability and measurement precision.
2Reliability
If the rotation detector is firmly attached to the shaft with fastening members, then the attachment is secure, but the attachment and detachment process becomes complex and time-consuming
Solution Approach 1:
The patent segments the attachment system into two independent parts: the Oldham coupling that provides mechanical connection and the washer that provides positioning and attachment functionality. This segmentation allows the rotation detector to be firmly secured through the washer while simplifying the overall attachment process by eliminating the need for multiple fastening members, thus improving both reliability and ease of manufacture.
3Device complexity
If conventional coupling methods are used, then the structure is simple, but axial displacements and vibrations affect the accuracy of rotation detection
Solution Approach 1:
The patent applies dynamics by designing the Oldham coupling with movable arms that can dynamically adjust to axial displacements and vibrations. The perpendicular arms of the coupling move independently to accommodate axial movement while maintaining rotational connection, allowing the system to adapt to dynamic conditions without compromising detection accuracy, thus resolving the contradiction between structural simplicity and measurement precision.
Data Source
AI summary
A rotating electric machine according to the embodiments includes a rotating-electric-machine unit, a rotation detector, an Oldham coupling, and a washer. The rotating-electric-machine unit includes a shaft. The rotation detector includes a body and a rotation input pin that is rotatably provided on the body. The Oldham coupling couples the rotation input pin of the rotation detector and the shaft to each other while allowing any relative displacement in a direction intersecting an axial direction. The washer is provided on the rotating-electric-machine unit while being positioned with respect to the shaft. The washer includes an attaching portion at which the body of the rotation detector is attached to the washer.