Variable Speed Direct Drive Transmission for Scooters
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Solution Overview
Problem
Existing transmission systems for scooters, go-carts, and motorcycles lack the ability to efficiently vary speed and torque without adding weight, complexity, or cost, and often compromise stability due to the need for multiple moving parts and axial movement of the drive unit, which can lead to instability and maintenance issues.
Innovation Solution
A direct drive transmission system utilizing a friction element guided along the primary axis of the motor drive shaft, with a roll bearing and spring mechanism, allowing for stepped or continuous variable transmission without axial movement of the motor or coupling mechanism, and featuring a conical transition zone for easy operation and reduced inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a basic throttle mechanism is used to control motor speed, then the vehicle structure remains simple and inexpensive, but the capability to adjust vehicle speed is limited
Solution Approach 1:
The drive shaft is segmented into multiple functional zones (first friction engagement zone, second friction engagement zone, third friction engagement zone) with different diameters, allowing each zone to engage the drive wheel at different positions to provide variable speed ratios without requiring a complex multi-gear transmission system
Solution Approach 2:
The system changes the effective radius parameter of the drive shaft by engaging different friction zones at different positions along the axial direction, thereby varying the transmission ratio and achieving speed adjustment without complex mechanical transmissions
2Adaptability or versatility
If multiple moving parts are used in the transmission system, then speed variation capability is improved, but vehicle stability deteriorates due to increased inertia
Solution Approach 1:
The drive shaft is divided into multiple friction engagement zones with different diameters positioned along its length, allowing speed variation by engaging different zones without requiring multiple separate moving components, thus maintaining vehicle stability
Solution Approach 2:
The friction element can dynamically shift its engagement position along the axial direction of the drive shaft, allowing continuous or stepped variation of the transmission ratio while maintaining a simple overall structure with minimal moving parts
3Adaptability or versatility
If axial movement of the drive unit is used for shifting, then speed variation is achieved, but ride stability deteriorates due to movement during operation
Solution Approach 1:
The friction element can shift between different engagement zones along the axial direction of the drive shaft during operation, enabling speed variation while the drive unit remains in a fixed position, thus maintaining ride stability
Solution Approach 2:
The shifting function is extracted from the drive unit as a whole and implemented instead by the friction element's ability to engage different zones of the drive shaft, eliminating the need for axial movement of the entire drive unit
4Adaptability or versatility
If conventional transmission systems are installed, then speed control capability is improved, but vehicle weight increases
Solution Approach 1:
The transmission function is merged into the drive shaft itself by creating multiple friction engagement zones with different diameters along its length, eliminating the need for separate transmission components and reducing overall vehicle weight
Solution Approach 2:
The drive shaft serves multiple functions: it transmits torque and simultaneously provides variable speed ratios through its different diameter zones, eliminating the need for dedicated transmission components and reducing vehicle weight
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides a user-friendly, lightweight, and low-maintenance solution that allows for variable speed transmission without disrupting the ride, minimizing instability and maintenance needs, while occupying minimal space between the drive wheel and propulsion system.
Implementation Method 1
a friction element which is movable in the direction of the primary axis of the motor drive shaft and which acts as a shift that changes the torque applied to the periphery of a wheel
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A direct drive transmission system suitable for use with scooters, go-carts or motorcycles is disclosed. The transmission system comprises a drive shaft coupled to a motor shaft and a friction element which is guided longitudinally on said drive shaft, rotating with the rotation of the drive shaft. The system further comprises a roll bearing fixedly attached around at least part of the periphery of its inner ring to an end of the friction element and a stopper which is fixedly attached to the outer ring of said roll bearing. The stopper is adapted to affix a wire, which when pulled, moves longitudinally said friction element towards the inner end of the drive shaft so as to allow engagement of said friction element onto a traction surface of the drive wheel.