Electric Machine Transmission Mounting for Minimal Rotor-Stator Air Gap
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Solution Overview
Problem
Electric machines in motor vehicles face challenges in minimizing the air gap between the rotor and stator while maintaining structural integrity due to weight-saving measures that increase rotor elasticity.
Innovation Solution
A method for arranging an electric machine on a transmission involves precise alignment and fixation of the stator housing, use of a centering pin for coaxial orientation, and a pivotally attached bearing device to compensate for tolerances, thereby reducing the air gap between the rotor and stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If weight-saving measures are taken to reduce electric machine weight, then the overall vehicle performance is improved, but the rotor elasticity increases which makes it difficult to minimize the air gap
Solution Approach 1:
A centering pin is introduced as an intermediary component during assembly to precisely align and center the rotor relative to the stator. This mediator compensates for the rotor's elastic deformation by providing a rigid reference axis, enabling accurate air gap control despite the lightweight, elastic rotor construction
Solution Approach 2:
The centering pin is inserted and secured in the stator cavity before the rotor is mounted. This preliminary action establishes the precise geometric relationship between stator and rotor, allowing the air gap to be minimized before the rotor's elastic properties can cause misalignment
2Weight of moving object
If the rotor is designed with higher elasticity for weight savings, then the vehicle performance increases, but the tolerances between transmission input shaft and rotor shaft become more difficult to control
Solution Approach 1:
The centering pin serves as a mediator that transfers the alignment precision from the rigid stator housing to the elastic rotor. By clamping the centering pin in the stator cavity and using it as a reference, the system achieves precise shaft alignment tolerances despite the rotor's high elasticity
Solution Approach 2:
The system changes the physical state of alignment control by introducing a temporary rigid element (centering pin) that constrains the rotor position during assembly. This parameter change allows precise tolerance control during the critical assembly phase before the rotor's elastic properties dominate
3Power
If the air gap between rotor and stator is minimized to increase power density, then the power density increases, but the structural integrity becomes compromised due to rotor elasticity
Solution Approach 1:
The centering pin is installed and the stator housing is aligned on the transmission before the rotor is inserted. This preliminary establishment of the precise geometric framework allows the air gap to be minimized to optimize power density while the centering pin prevents excessive rotor displacement that would compromise structural integrity
Solution Approach 2:
The centering pin acts as a mediator that enables the rotor to operate at minimal air gap distances without compromising structural integrity. The pin provides a rigid reference that prevents the elastic rotor from deflecting beyond safe limits during operation
Data Source
AI summary
A method for arranging an electric machine on a transmission, having the steps of providing a stator housing, inserting a hollow cylindrical stator into the stator housing such that the stator is rotationally fixed in the stator housing, and aligning the stator housing with the transmission. Additional steps include securing the stator housing on the transmission, inserting a rotor having a rotor hollow shaft into the stator, securing the rotor to a transmission input shaft, placing a bearing shield having a bearing pin on a receiving opening of the stator housing such that the bearing pin engages in a rotor cavity of the rotor hollow shaft and in a pivotally attached bearing device arranged in the rotor cavity such that the rotor is mounted so as to be rotatable about the rotor longitudinal axis.