Compact Motorcycle Engine Unit with Overlapping Clutch Configuration
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Solution Overview
Problem
Conventional motorcycles face challenges in mounting multi-speed transmissions with multiple clutches due to limited space, requiring a compact design that maintains weight balance and reduces shaft-to-shaft distance without increasing the vehicle's width, while accommodating the weight and size of clutches.
Innovation Solution
The engine unit incorporates a crankshaft, output shaft, main shaft, transmission shaft, propeller shaft, and a drive unit case with a transmission gear mechanism, where the main shaft projects beyond the output shaft, and the clutch is positioned to overlap with an intermediate gear, allowing for a compact configuration with multiple clutches that maintain lateral balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple clutches are arranged on both left and right sides of the vehicle body to maintain lateral balance, then weight balance is improved, but the transmission size and shaft-to-shaft distance increase
Solution Approach 1:
The patent positions clutches at different axial locations along the main shaft rather than symmetrically on left and right sides. Specifically, the first clutch is positioned near one end of the main shaft while the second clutch is positioned near the other end, utilizing the axial dimension to achieve weight balance without increasing lateral width or transmission volume.
Solution Approach 2:
The transmission system is segmented into distinct clutch positions along the main shaft, with each clutch independently positioned to optimize space utilization. This segmentation allows clutches to be distributed along the axial length of the main shaft, reducing the need for lateral spacing and minimizing overall transmission size.
2Stability of the object's composition
If clutches are positioned away from each other to maintain lateral balance, then weight distribution is improved, but the device complexity increases
Solution Approach 1:
The main shaft serves multiple functions: it supports the crankshaft, transmits power to the counter shaft, and provides mounting positions for multiple clutches at different axial locations. This multi-functionality reduces the need for additional support structures and simplifies the overall transmission architecture while maintaining weight balance.
3Area of stationary object
If the transmission is made compact to fit limited mounting space, then mounting space requirement is reduced, but the ease of operation for gear changes deteriorates
Solution Approach 1:
The clutches are pre-positioned at optimal locations along the main shaft during manufacturing, with the first clutch near one end and the second clutch near the other end. This preliminary positioning ensures that gear change operations can be performed efficiently without requiring complex adjustments or repositioning during operation, maintaining ease of operation despite the compact design.
Data Source
AI summary
In an engine unit, a drive unit case includes a crank shaft disposed in a left-right direction of a vehicle, a drive shaft and a second main shaft. A transmission shaft is parallel or substantially parallel to the drive shaft and transmits rotational power, which has been transmitted via a middle gear, to a propeller shaft. A second clutch, which transmits rotational power from the crank shaft to the second main shaft, is freely detachably connected to an end of one side of the second main shaft which protrudes from a drive unit case more than the end of one side of the drive shaft, at a position that overlaps with at least one section of the middle gear on the side of the shaft direction of the drive shaft.