Electric Drive Axle Layout With Rotor-Mounted Input Gears
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Solution Overview
Problem
The independent bearing systems for the input gear shaft and rotor shaft in electric drive axles lead to misalignment, reducing efficiency and increasing wear, thereby shortening the useful life and increasing costs due to premature component replacement.
Innovation Solution
An electric drive assembly with a rotor shaft supported by two bearings, where the input gears are mounted directly on the rotor shaft, eliminating the need for a dedicated input shaft, and a multi-piece housing that allows for efficient assembly and cooling jacket formation, reducing the size and weight of the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated input shaft with independent bearings is used, then the gearbox structure is complete and functional, but misalignment develops between the input gear shaft and rotor shaft, reducing efficiency and increasing wear
Solution Approach 1:
The patent merges the input shaft and rotor shaft into a single common shaft structure. The input gears are mounted directly on the rotor shaft, eliminating the need for a separate dedicated input shaft. This integration ensures that the input gears and rotor are always aligned since they share the same rotational axis, preventing misalignment issues while reducing the number of components and assembly complexity.
2Productivity
If a dedicated input shaft with independent bearings is used, then the gearbox can function properly, but the size and weight of the electric drive assembly increase
Solution Approach 1:
The patent combines the input shaft and rotor shaft into one common shaft, eliminating redundant components. By mounting input gears directly on the rotor shaft, the design removes the dedicated input shaft and its independent bearing set, thereby reducing overall assembly weight while maintaining proper gear engagement and power transmission functionality.
Solution Approach 2:
The patent extracts and removes the dedicated input shaft from the system. Instead of including a separate input shaft with its own bearings, the design uses only the rotor shaft to support both the rotor and input gears, eliminating unnecessary weight while preserving the gearbox's operational capabilities.
3Ease of manufacture
If a multi-piece housing with overlapping sections is used, then assembly time is reduced and manufacturing efficiency increases, but the housing structure becomes more complex
Solution Approach 1:
The patent divides the housing into multiple separate pieces that can be manufactured independently and then assembled together. The housing includes a first housing section that receives the motor and a second housing section that receives the gearbox, allowing each section to be produced separately using optimized manufacturing processes and then joined through overlapping connections.
Solution Approach 2:
The patent uses a nested housing structure where the first and second housing sections overlap and interlock. The housing sections are designed to fit together in a nested arrangement, with one section partially receiving the other, creating a compact integrated structure that simplifies assembly while maintaining structural integrity.
Data Source
AI summary
Systems are provided for increasing an efficiency of an electric drive axle, and reducing a number of components and weight of the axle. In one example, an electric drive assembly comprises an electric motor having a rotor shaft supported by a first rotor shaft bearing and a second rotor shaft bearing; a gearbox having a layshaft layout, where at least one input gear of the gearbox is mounted on the rotor shaft; and a multi-piece housing, the multi-piece housing including a first housing section supporting the first rotor shaft bearing and a stator of the electric motor; the first housing section defining an inner boundary of a motor cooling jacket; and a second housing section partially overlapping with the first housing section, the second housing section partially enclosing the gearbox and partially enclosing the electric motor; the second housing section defining an outer boundary of the motor cooling jacket.