Electric Drive Axle Gear Train Layout for Compact Precision Grinding
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Solution Overview
Problem
Previous electric drive axle gearboxes face challenges in achieving precise gear grinding while maintaining a compact design, leading to inefficiencies in packaging and increased noise, vibration, and harshness (NVH).
Innovation Solution
The gear train design includes an intermediate shaft with gears of different sizes, where a larger gear is positioned between two smaller gears, allowing for precise cutting and grinding, and a park gear is compactly arranged to enhance space efficiency and reduce NVH. The manufacturing method involves forming a first gear on the outer surface of the intermediate shaft, press-fitting a second gear, and installing a third gear onto an axial section, ensuring high accuracy and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional gear manufacturing techniques are used to achieve precise gear grinding, then gear precision is improved, but the packaging space efficiency deteriorates
Solution Approach 1:
The patent implements nesting by placing the second gear inside the axial extension of the third gear, where the interior surface of the second gear circumferentially surrounds the outer surface of the third gear's axial extension. This nested arrangement allows multiple gears to occupy overlapping radial spaces, achieving compact packaging while maintaining precise gear grinding through conventional manufacturing techniques.
Solution Approach 2:
The patent utilizes the axial dimension by extending the third gear axially and positioning the second gear in the radial direction around this extension. This three-dimensional arrangement transforms a traditionally two-dimensional gear layout into a compact three-dimensional configuration, enabling precise gear manufacturing without compromising packaging space efficiency.
2Volume of moving object
If gears are arranged in a compact configuration, then space efficiency is improved, but gear manufacturing precision deteriorates
Solution Approach 1:
The nested gear arrangement with the second gear surrounding the axial extension of the third gear enables compact packaging while maintaining manufacturing precision. The concentric nesting geometry provides stable reference surfaces for precision gear grinding, as the inner and outer surfaces can be machined with high accuracy using conventional techniques.
Solution Approach 2:
The axial extension of the third gear is formed as a preliminary structural feature that serves as a mounting surface for the second gear. This preliminary action of creating the axial extension with precise dimensions enables subsequent precision gear grinding of both gears while maintaining their compact nested relationship.
3Ease of manufacture
If conventional gear arrangements are used, then ease of manufacture is improved, but noise, vibration, and harshness increase
Solution Approach 1:
The nested gear configuration reduces NVH by minimizing the radial footprint and enabling better alignment between meshing gears. The concentric arrangement of the second gear around the third gear's axial extension provides stable mounting and reduced vibration, while still using conventional manufacturing processes to maintain ease of manufacture.
Solution Approach 2:
By transitioning to a three-dimensional nested gear arrangement, the patent achieves improved NVH characteristics through better gear mesh alignment and reduced radial forces, while maintaining ease of manufacture through conventional machining processes applied to the axially extended gear structure.
Data Source
AI summary
Methods and systems for an electric drive axle of a vehicle are provided. A gear train in an electric drive axle system includes, in one example, an input shaft configured to rotationally couple to an electric motor-generator and including a first gear and an intermediate shaft including a second gear rotationally coupled to the first gear and a third gear and a fourth gear each configured to rotationally couple to a separate gear on an output shaft. In this example, the second gear, the third gear, and the fourth gear have different sizes, the third gear includes an axial extension having at outer surface, and an interior surface of the second gear circumferentially surrounds at least a portion of the outer surface of the axial extension.