Homokinetic Motorcycle Transmission via Offset Joint
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Solution Overview
Problem
Current motorcycle transmission systems face challenges such as the need for continuous maintenance of chain transmissions and the non-instantaneous homokinetic nature of cardan joint transmissions, which also impose geometric constraints and increase costs/weights, limiting comfort and dynamic behavior.
Innovation Solution
A motorcycle transmission system utilizing a homokinetic joint offset from the swingarm's hinging end, combined with a geared coupling, allowing instantaneously constant transmission ratio and oscillation, eliminating the need for a cardan joint and enabling flexible squat angle adjustment without excessive weight or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a chain transmission is used, then the transmission is lightweight and inexpensive, but it requires continuous maintenance and has limited durability
Solution Approach 1:
The patent replaces the chain-pinion-crown mechanical transmission system with a cardan joint-based mechanical system. This substitution eliminates the need for chain lubrication and adjustment, providing maintenance-free operation while maintaining lightweight characteristics. The cardan joint universal coupling mechanism transmits power from the crankshaft to the rear wheel without requiring continuous maintenance like chain transmissions.
Solution Approach 2:
The patent modifies the transmission ratio characteristics by using a cardan joint system that can achieve different angular relationships between input and output shafts. By changing the geometric parameters of the cardan joint and its mounting position, the system achieves instantaneous homokinetic transmission while maintaining lightweight construction, thereby improving reliability without sacrificing the weight advantage.
2Reliability
If a cardan joint transmission is used, then maintenance is minimized, but the transmission is heavier and more expensive
Solution Approach 1:
The patent uses a simplified cardan joint mechanism instead of heavier universal joint assemblies with multiple bearings and housings. By substituting the complex universal joint system with a streamlined cardan joint that directly couples the crankshaft and rear wheel, the maintenance-free operation is achieved while significantly reducing the transmission weight and cost.
3Device complexity
If a cardan joint transmission is used, then the structure is simplified, but the transmission ratio varies sinusoidally over time reducing comfort
Solution Approach 1:
The patent employs asymmetric mounting of the cardan joint where the input and output shafts are positioned at specific non-symmetric angles. This asymmetric configuration, with the cardan joint axis oriented perpendicular to the plane containing both shafts, creates instantaneous homokinetic transmission characteristics that eliminate sinusoidal variations in transmission ratio, thereby improving rider comfort while maintaining structural simplicity.
Data Source
AI summary
A motorcycle transmission (4) comprising a swingarm (8) which extends from one hinging end (12) to a motorcycle chassis, defining an oscillation axis (X-X), at one connection end (16) to a wheel (20), a homokinetic joint (36) arranged on the side of the hinging end (12), and a a geared coupling (40) positioned on the side of the connection end (16), wherein the homokinetic joint (36) kinematically reciprocally connects a first end (44) of an input shaft (48), connected to a power take-off, and a second end (52) of an output shaft (56) mechanically connected to the geared coupling (40), and wherein the geared coupling (40) transmits the motion to the wheel (20). The homokinetic joint (36) performs an instantaneously constant transmission ratio between the first and the second end (44, 52), the homokinetic joint (36) is offset to the hinging end (12) of the swingarm (8), in a vertical direction (Y-Y) perpendicular to the support surface (P) of the wheel (20) and permits an oscillation of the output shaft (56) between a stroke start and a stroke end, parallel to the oscillation axis (X-X).