Rotor End Plate Radial Stability via Segmented Fastening
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Solution Overview
Problem
Rotors for rotary electric machines experience jolts and abnormal noises due to radial movement of end plates caused by thermal expansion, which existing designs fail to adequately address.
Innovation Solution
A rotor design featuring a rotational shaft with a flange, a magnetic rotor core, non-magnetic end plates, an iron-based fixing plate, and mounting bolts that securely fit and fix the end plates to prevent axial and radial movement through shrink or press fitting, ensuring a sufficient retaining force and eliminating gaps between the shaft and end plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If end plates are made of non-magnetic material with higher linear expansion coefficient than the rotational shaft, then thermal expansion is accommodated, but gaps form between the shaft and end plates causing radial movement
Solution Approach 1:
The end plate assembly is segmented into multiple components: the end plate itself, a retaining ring, and a snap ring. This segmentation allows each component to perform a specific function - the end plate accommodates thermal expansion, while the retaining and snap rings independently provide radial positioning and prevent gaps from causing instability.
Solution Approach 2:
A retaining ring is introduced as an intermediary component between the end plate and the rotational shaft. This retaining ring fits into a groove on the end plate and engages with the shaft, mediating the connection and preventing radial movement while allowing the end plate to expand thermally.
2Stability of the object's composition
If end plates are fitted to rotational shaft by shrink fitting or press fitting, then radial movement is prevented, but assembly complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of fitting the end plate directly onto the shaft through shrink or press fitting, the design inverts the approach by using a retaining ring that fits into a groove on the end plate and then engages with the shaft. This reversal simplifies assembly as the components can be installed in a more straightforward sequence without requiring complex fitting processes.
Solution Approach 2:
The retaining ring is designed to be preliminarily installed into a groove on the end plate before the end plate assembly is mounted on the shaft. This preliminary action ensures proper positioning and simplifies the subsequent assembly process, as the retaining ring is already in place to guide and secure the end plate.
3Stability of the object's composition
If mounting bolts are used to fix the second end plate to the fixing plate, then radial movement is suppressed, but the number of parts and assembly steps increases
Solution Approach 1:
The mounting bolts serve a dual function: they secure the second end plate to the fixing plate and simultaneously act as the fixing tool itself. This merging of functions reduces the need for separate fixing tools and simplifies the overall assembly process while maintaining radial position stability.
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 design effectively suppresses jolts and abnormal noises by preventing radial movement of the end plates, maintaining structural integrity and reducing operational noise, while also downsizing the rotor through depression features in the end plates for mounting bolts.
Implementation Method 1
has an inner diameter set such that the first end plate is fitted to the rotational shaft by shrink fitting or press fitting
Implementation Method 2
has an inner diameter set such that the first end plate is fitted to the rotational shaft by shrink fitting or press fitting
Implementation Method 3
a fixing tool that couples and fixes the second end plate to the fixing plate
Implementation Method 4
the collar and the flange of the rotational shaft to axially tighten and fix the rotor core and the end plates
Implementation Method 5
the collar and the flange of the rotational shaft to axially tighten and fix the rotor core and the end plates
Data Source
AI summary
A rotor for a rotary electric machine includes: a rotational shaft that is made of an iron-based metal, and includes a flange; a cylindrical rotor core that is made of a magnetic material, and includes a slot axially extending through the rotor core; a permanent magnet inserted in the slot; an annular first end plate that is made of a non-magnetic material, is shrink-fitted or press-fitted to the rotational shaft, and closes an opening of the slot; an annular fixing plate that is made of an iron-based metal, is shrink-fitted or press-fitted to the rotational shaft, and is disposed radially innerly with respect to the slot; an annular second end plate that is made of a non-magnetic material, includes a recession containing the fixing plate, and closes an opening of the slot; and a fixing tool coupling the second end plate to the fixing plate.