EV Drive Unit Layout With Partition Opening for Equal Shaft Lengths
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Solution Overview
Problem
Existing vehicle drive devices with rotary electric machines and differential devices are bulky, leading to uneven drive shaft lengths and reduced vehicle drivability, which necessitates additional components to adjust lengths, thereby increasing costs.
Innovation Solution
A vehicle drive device configuration that includes a rotary electric machine, a power transmission mechanism, a differential device, and a case with a partition wall having an opening at the shortest distance between the stator core and the differential device, allowing for closer proximity without axial shifting, thus enabling downsizing without increased costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotary electric machine and differential device are disposed widely in the axial direction to avoid interference, then the stator and differential device do not interfere with each other, but the drive shaft lengths become uneven on the right and left sides, deteriorating vehicle drivability
Solution Approach 1:
The patent transitions from axial direction arrangement to radial direction arrangement. By bringing the first axis (rotary electric machine) and third axis (differential device) closer in the radial direction rather than maintaining wide separation in the axial direction, the invention achieves both compact overall size and equal drive shaft lengths, resolving the contradiction between axial length and drivability
Solution Approach 2:
The patent employs asymmetric positioning of the rotary electric machine and differential device. The first axis and third axis are positioned at different radial distances from the case center, with the rotary electric machine closer to the center and the differential device farther out. This asymmetric arrangement allows the drive shafts to have equal lengths while avoiding interference between the stator and differential device
2Volume of stationary object
If the first axis and third axis are brought closer to each other to downsize the case, then the overall size is reduced, but additional output shafts are needed to adjust drive shaft lengths, increasing costs
Solution Approach 1:
The patent uses asymmetric positioning where the first axis and third axis are at different radial distances from the case center. This asymmetric arrangement naturally equalizes the drive shaft lengths, eliminating the need for additional output shafts or length-adjustment mechanisms, thus downsizing the case without increasing device complexity or costs
Solution Approach 2:
The patent changes the spatial parameters of the axis positions. By optimizing the radial distances of the first and third axes from the case center, the invention achieves equal drive shaft lengths and compact case size simultaneously, avoiding the need for additional components
Data Source
AI summary
A vehicle drive device includes a rotary electric machine including a stator and a rotor, a power transmission mechanism drivingly connected to the rotor, a differential device including a differential ring gear, a differential case, and a differential mechanism, and a case. The case includes a partition wall disposed between the rotary electric machine and the differential device. The partition wall has an opening at a portion where a distance between a stator core and the differential device is shortest so that part of the stator core is exposed on a differential device side.