EV Power Unit Layout With Inboard Drive Sprocket
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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 mechanism can be simplified, but the vehicle size and power unit size increase
Solution Approach 1:
The drive sprocket is positioned in the vehicle width direction at a location inward of the output gear, utilizing the spatial dimension within the gear case cover to achieve compact arrangement. This dimensional repositioning allows the drive sprocket to be located at coordinates that reduce the overall vehicle width while maintaining functional requirements.
Solution Approach 2:
The drive sprocket is nested within the spatial envelope defined by the output gear's inward position. By placing the drive sprocket inward of the output gear in the vehicle width direction, the components are arranged in a nested configuration that maximizes space utilization and minimizes the external dimensions of the power unit.
2Ease of manufacture
If the drive sprocket is positioned outward in the vehicle width direction, then the drive chain can be easily routed, but the chain line protrusion increases
Solution Approach 1:
The drive sprocket is repositioned in the vehicle width direction to an inward location relative to the output gear. This dimensional change in positioning reduces the chain line protrusion in the vehicle width direction while the drive chain is routed through the gear case cover to maintain ease of connection and routing.
3Volume of moving object
If the drive sprocket is positioned inward of the output gear, then the vehicle size is reduced, but the power transmission mechanism becomes more complex
Solution Approach 1:
The drive sprocket is nested within the spatial boundaries defined by the output gear's inward position. This nested arrangement allows compact component placement that reduces vehicle size while the complexity is managed through the integrated gear case cover structure that houses and connects all transmission components.
Solution Approach 2:
The gear case cover serves multiple functions: it encloses the gear case, provides mounting for the drive sprocket, and facilitates drive chain routing. By merging these functions into a single integrated component, the design achieves compact size without proportionally increasing mechanism complexity.
Data Source
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AI summary
A power unit (30) in which a gear case (41) is provided on one side, in a vehicle width direction, of a motor case (32, 39). An opening of the gear case (41) is covered with a gear case cover (51) from an outside in the vehicle width direction. The power unit (30) includes a motor shaft (62) protruding toward the gear case (41) from a motor case side, a drive shaft (65) protruding outward from the gear case cover (51), and a power transmission mechanism (70) configured to transmit, to the drive shaft (65), power from the motor shaft (62). An output gear (63) is fixed to the motor shaft (62), inside the gear case cover (51). A drive sprocket (67) is fixed to the drive shaft (65), outside the gear case cover (51). The drive sprocket (67) is positioned inward of the output gear (63).