Power Unit Gear Layout for Reduced EV Chain Line Protrusion
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Solution Overview
Problem
Existing electric vehicle power units are large due to the protrusion of the drive chain line in the vehicle width direction, which increases the overall size of both the vehicle and the power unit.
Innovation Solution
A power unit design where the gear case is positioned on one side of the motor case with the drive sprocket positioned inward of the output gear, allowing the power transmission mechanism to be compactly formed and preventing the drive sprocket from protruding outward, thus reducing the chain line's protrusion and overall size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the drive sprocket is positioned outward in the vehicle width direction, then the power transmission is simplified, but the vehicle size and power unit size increase
Solution Approach 1:
The patent combines the drive sprocket and output gear into a single integrated component that rotates together on the same shaft. This merging allows the drive sprocket to be positioned inward (inside the vehicle width direction) while maintaining both the driving function (via the sprocket) and the gear transmission function (via the output gear), thereby reducing vehicle width without complicating the power transmission mechanism.
Solution Approach 2:
The integrated drive sprocket-output gear assembly serves multiple functions simultaneously: it acts as both the drive sprocket for the drive chain and the output gear for the reduction gear train. This multi-functionality eliminates the need for separate components positioned outward, reducing the overall vehicle size while maintaining effective power transmission.
2Volume of moving object
If the drive sprocket is positioned inward in the vehicle width direction, then the vehicle size is reduced, but the power transmission mechanism becomes more complex
Solution Approach 1:
The patent resolves the complexity issue by merging the drive sprocket and output gear into a single integrated component. This integration simplifies the overall structure compared to having separate components, as it reduces the number of parts and mounting requirements while enabling the drive sprocket to be positioned inward for compact vehicle design.
3Ease of manufacture
If the chain line protrudes outward, then the drive chain can be easily routed, but the power unit size increases
Solution Approach 1:
By integrating the drive sprocket with the output gear, the patent enables the drive chain to be routed through the gear case cover along a more compact path. The merged component allows the chain line to remain accessible for easy routing while being positioned inward, thus reducing the power unit size without sacrificing manufacturing ease.
Data Source
AI summary
A power unit in which a gear case is provided on one side, in a vehicle width direction, of a motor case. An opening of the gear case is covered with a gear case cover from an outside in the vehicle width direction. The power unit includes a motor shaft protruding toward the gear case from a motor case side, a drive shaft protruding outward in the vehicle width direction from the gear case cover, and a power transmission mechanism configured to transmit, to the drive shaft, power from the motor shaft. An output gear is fixed to the motor shaft, inside the gear case cover. A drive sprocket is fixed to the drive shaft, outside the gear case cover. The drive sprocket is positioned inward, in the vehicle width direction, of the output gear.