Compact Drivetrain via Intermediate Shaft for SSV
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Solution Overview
Problem
Conventional small-sized vehicles with direct transmission to rear-wheel differential units face the challenge of increased vertical size due to the need for larger gears, leading to a larger differential unit in the vertical direction.
Innovation Solution
Incorporating an intermediate shaft portion that transmits the engine's driving force to the rear-wheel differential unit, which includes an intermediate gear to prevent the gear for rotation from becoming large, allowing the differential unit to be positioned either above or below the rear output shaft, thereby reducing the overall height and maintaining a compact profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a differential part is driven directly by a transmission gear mechanism, then the transmission is simplified, but the diameter of the input gear becomes large causing the differential part to become large in vertical direction
Solution Approach 1:
An intermediate shaft is introduced between the transmission gear mechanism and the differential unit. This intermediate shaft carries an input gear that meshes with the output gear of the transmission, allowing the differential unit to be driven without requiring a large-diameter input gear. The intermediate shaft acts as a mediator that transfers rotational motion while enabling a more compact vertical configuration.
Solution Approach 2:
The intermediate shaft is arranged to extend in the vehicle width direction (lateral dimension) rather than vertically. By orienting the intermediate shaft laterally and positioning the differential unit above or below it, the design transfers the gear transmission function to a different spatial dimension, thereby reducing the vertical size of the differential unit.
2Adaptability or versatility
If the rear output shaft is inclined to accommodate vehicle design requirements, then the vehicle layout is optimized, but the differential unit position becomes constrained (too high or too low)
Solution Approach 1:
The system allows the differential unit to be positioned dynamically relative to the intermediate shaft - either above or below it - depending on the inclination of the rear output shaft and vehicle design requirements. This dynamic positioning capability enables the vehicle layout to be optimized without constraining the differential unit to a fixed vertical position.
Solution Approach 2:
The drivetrain is segmented into distinct components: the rear output shaft, the intermediate shaft, and the differential unit. This segmentation allows each component to be independently positioned and optimized. The intermediate shaft serves as a separate element that decouples the vertical positioning constraints between the rear output shaft and the differential unit.
Data Source
AI summary
A small-sized vehicle (SSV) capable of inhibiting a differential unit from becoming large in a vertical direction includes an engine, a rear output shaft portion arranged to extend rearwardly of the engine and serving to transmit a driving force of the engine rearward, an intermediate shaft portion rotated by the rear output shaft portion and extended in a vehicle width direction, a rear-wheel differential unit rotated by the intermediate shaft portion and serving for differential movements of a pair of rear-wheel axle shafts connected to a pair of rear wheels.