Rear Swing Arm Transmission Layout for Compact Electric Two-Wheelers
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Solution Overview
Problem
The challenge in electric vehicle design is to achieve compact, cost-effective, and efficient packaging of the prime mover and transmission system in limited space, particularly in two-wheeler vehicles, while maintaining aesthetics and ensuring balanced weight distribution for improved handling and stability.
Innovation Solution
The solution involves a closely coupled electric motor and transmission system integrated within the rear wheel dimensions, where the transmission casing acts as a swing arm and rear suspension member, reducing the need for separate suspension components and optimizing weight distribution by positioning the battery centrally for balanced weight distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the battery is placed at the central lower position for better balance and handling, then the vehicle's weight distribution is improved, but the overall longitudinal length of the vehicle increases
Solution Approach 1:
The transmission system is nested within the swing arm structure, with the transmission casing forming part of the rear suspension system. This nesting allows the transmission components to be housed within the existing structural envelope of the swing arm, avoiding additional longitudinal space requirements while maintaining central lower battery placement for optimal weight distribution.
Solution Approach 2:
The swing arm is designed to serve multiple functions: it acts as both the rear suspension component and the transmission system housing. The transmission casing is integrated into the swing arm structure, allowing the same structural element to perform both suspension and power transmission functions, thereby eliminating the need for separate transmission mounting space that would increase vehicle length.
2Volume of moving object
If the electric motor and transmission system are packaged in limited space, then the vehicle size is reduced, but the packaging complexity increases
Solution Approach 1:
The transmission system is merged with the swing arm structure by making the transmission casing form an integral part of the rear suspension system. This consolidation combines two previously separate systems (transmission and suspension) into a single integrated structure, reducing overall packaging space while actually simplifying the design by eliminating separate mounting requirements and reducing the number of components.
Solution Approach 2:
The swing arm structure is designed to perform multiple functions simultaneously: it provides rear suspension functionality while also housing the transmission system. This multi-functionality allows the transmission components to be accommodated within the existing structural envelope of the swing arm, reducing packaging space requirements without adding significant design complexity.
3Device complexity
If the transmission system is integrated into the swing arm structure, then the number of separate components is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The integrated swing arm-transmission structure is designed as a modular assembly where the transmission casing forms a distinct but integrated portion of the swing arm. This segmentation approach allows for separate manufacturing of the transmission components and swing arm structure, which can then be precision-assembled using standardized mounting interfaces, thereby reducing the overall manufacturing precision requirements compared to a fully monolithic design.
Data Source
AI summary
An electric vehicle (10) comprising: a frame (11); an electric battery module (24) comprising at least one battery connected to the frame; an electric motor (20) receiving power from the battery module (24); a transmission system (80) provided with a transmission casing (208B); said electric motor (20) is closely coupled to the transmission system (80) and is mounted on the transmission casing (208B); and a rear wheel (84) receiving power from the electric motor (20) through the transmission system (80) and said rear wheel (84) is connected to the frame using a rear suspension system; wherein the rear wheel (84) is connected to the frame (11) using said casing (208B) forming a part of the rear suspension system.