Plastic-Fixed Rotor Magnet Pockets for a Homogeneous Air Gap
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Solution Overview
Problem
Electric machines in hybrid or fully electric vehicles face challenges in achieving high power density while minimizing noise and vibration, which are often trade-offs in existing designs.
Innovation Solution
A rotor design featuring a laminated rotor core with pockets for rotor magnets fixed by injected plastic, ensuring precise roundness and a homogeneous air gap between the rotor and stator, reducing undesirable vibrations and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rotor magnets are fixed in pockets using conventional methods, then manufacturing is simpler, but the roundness of the rotor body and homogeneity of the air gap deteriorate, leading to increased vibrations and noise
Solution Approach 1:
The invention merges the rotor magnet fixation function with the air gap homogenization function by integrating plastic injection into the rotor body pockets. The plastic serves dual purposes: securing the rotor magnets in place and simultaneously compensating for contour deviations to maintain a homogeneous air gap, thereby resolving the contradiction between manufacturing precision and device complexity.
Solution Approach 2:
The invention uses composite construction by combining the rotor core, rotor magnets, and plastic material into an integrated structure. The plastic acts as a composite material that fills the gaps between the rotor magnets and the rotor body, creating a unified structure that improves both fixation stability and air gap homogeneity without requiring separate components.
2Power
If high electromagnetic excitation is used to increase power density, then power output improves, but acoustic vibrations in structural components increase, leading to higher noise levels
Solution Approach 1:
The invention applies beforehand cushioning by pre-installing plastic material in the rotor body pockets before the rotor operates at high power. This plastic cushioning compensates for contour deviations and provides vibration damping, allowing the rotor to withstand high electromagnetic excitation forces without generating excessive acoustic vibrations, thus enabling high power density while controlling noise.
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 achieves improved power density and reduced noise by maintaining a precise air gap, enhancing operational efficiency and comfort in electric vehicles.
Implementation Method 1
the rotor magnets being fixed in the pockets of the first group by an injected plastic
Implementation Method 2
The plastic is introduced into the pockets of the rotor body using a transfer molding process
Data Source
AI summary
The invention relates to a rotor (1) for an electric machine (2), said rotor comprising a cylindrical rotor body (4) formed from a laminated rotor core (3) and having a plurality of pockets (5) for receiving rotor magnets (6), at least a first group (7) of pockets (5) extending in a substantially tangential direction, and the rotor magnets (6) being fixed in the pockets (5) of the first group (7) by an injected plastic (8), the pockets (5) of the first group (7) having a radially outer contour (9) which substantially corresponds to the radially outer arcuate contour of the cylindrical rotor body (4) in each case radially above the pockets (5) of the first group (7), plastic (8) being provided in each case between the radially outer contour (9) of one of the pockets (5) of the first group (7) and the rotor magnet (6) fixed in the pocket (5).