Electric Motor Output Shaft Layout for Compact E-Axle Assembly
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Solution Overview
Problem
The challenge in electric vehicle technology is to create a compact electric axle configuration that minimizes interference with vehicle features like suspension and braking systems while ensuring easy assembly and maintenance, particularly for heavy-duty vehicles.
Innovation Solution
The electric motor design features a rotor shaft with offset lateral portions and an output shaft secured by interference fit, utilizing rolling bearing assemblies to transmit axial and radial loads, reducing the need for additional bearing assemblies and facilitating easy gear replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the electric motor is positioned directly on the wheel axle (E-axle configuration), then transmission losses are reduced and vehicle performance is improved, but the motor becomes more complex and harder to maintain
Solution Approach 1:
The rotor shaft is segmented into a central portion and two lateral portions, with the output shaft and gear forming a separable assembly. This segmentation allows the gear and output shaft to be replaced independently without replacing the entire motor, reducing maintenance complexity while maintaining the compact E-axle configuration.
2Volume of moving object
If the electric motor is positioned directly on the wheel axle (E-axle configuration), then space for batteries is increased, but assembly and maintenance become more difficult
Solution Approach 1:
The output shaft is designed as a separate component that can be independently assembled to the rotor shaft via interference fit. The gear is integral with the output shaft, forming a pre-assembled unit. This segmentation enables simplified assembly procedures and easier maintenance while preserving the compact E-axle design that maximizes battery space.
3Device complexity
If the output shaft is fixedly secured to the rotor shaft by interference fit, then the number of bearing assemblies is reduced, but assembly precision requirements increase
Solution Approach 1:
The interference fit parameters (dimensions, tolerances, material properties) are specifically designed to achieve the optimal balance between reducing bearing assembly complexity and maintaining manufacturability. By carefully selecting the interference fit parameters, the patent reduces the number of bearing assemblies needed while keeping assembly precision requirements within reasonable limits.
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
This configuration enhances axial compactness, simplifies assembly and maintenance, and improves load bearing efficiency, while maintaining motor performance.
Implementation Method 1
the output shaft being fixedly secured with the second lateral portion of the rotor shaft by interference fit of the inner end with the rotor shaft
Implementation Method 2
a first rolling bearing assembly, the first lateral portion of the rotor shaft being mounted with the housing via the first rolling bearing assembly
Implementation Method 3
One of the first and second rolling bearing assembly is configured to transmit radial loads exerted on the rotor shaft, radially to the main axis, to the housing
Implementation Method 4
the other of the first and second rolling bearing assembly is configured to transmit radial loads exerted on the rotor shaft, radially to the main axis, to the housing and is configured to transmit axial loads exerted on the rotor shaft, along the main axis, to the housing
Data Source
AI summary
An electric motor has a housing, a stator, a rotor with a rotor shaft, an output shaft fixedly secured with the rotor shaft by interference fit and driven in rotation by the rotor shaft, and a gear, integral with the output shaft. The electric motor is configured so that axial loads exerted on the gear are transmitted to the rotor shaft via the output shaft. The rotor shaft is mounted with the housing via a first rolling bearing assembly and a second bearing assembly located on either sides of the stator, among which one transmits radial loads exerted on the rotor shaft to the housing and the other transmits radial loads and axial loads exerted on the rotor shaft to the housing.