Ball-Cam Friction Clutch for Low-Resistance Back Torque Cutoff
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Solution Overview
Problem
Existing friction clutches with back torque limiter mechanisms experience high working resistance due to surface contact, making it difficult to cut off back torque effectively, especially in high engine speed conditions, leading to unstable motorcycle performance.
Innovation Solution
A friction clutch with a ball cam working mechanism that includes driving and driven side cam grooves with varying inclination angles, allowing a ball to roll and move the first rotor apart from the second rotor, reducing torque transmission and cutting off back torque with lower resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If surface contact is used for torque transmission between rings, then structural simplicity is maintained, but working resistance increases and back torque cutoff capability deteriorates
Solution Approach 1:
The patent replaces surface contact with point contact by introducing cam surfaces with curved profiles and cam followers. The cam surfaces have specific curvature radii that enable smooth rolling motion, converting the sliding friction of surface contact into rolling friction of point contact, thereby reducing working resistance while maintaining structural compactness.
Solution Approach 2:
The patent introduces cam followers as intermediary elements between the first and second rings. These cam followers transmit torque through point contact with the cam surfaces, acting as mediators that reduce direct surface contact between rings. The cam followers enable efficient torque transmission with minimal working resistance while maintaining the back torque limiter function.
2Ease of operation
If half-clutch operation is used to control engine brake, then engine speed increase is relaxed, but driver burden increases during severe operations
Solution Approach 1:
The patent implements a self-regulating back torque limiter mechanism that automatically activates when back torque exceeds a predetermined threshold. The cam mechanism automatically reduces torque transmission from the output shaft to the engine without requiring driver intervention, enabling the system to self-manage engine brake control during severe operations and maintain stability.
Solution Approach 2:
The cam mechanism provides automatic feedback control by sensing the back torque level through the engagement of cam surfaces. When back torque exceeds the threshold, the cam geometry automatically adjusts torque transmission, creating a closed-loop control system that maintains motorcycle stability without driver input during critical situations.
3Reliability
If back torque limiter cuts off torque at high regulation value, then working resistance decreases, but engine brake becomes too strong causing slip and hopping
Solution Approach 1:
The patent precisely controls the back torque cutoff regulation value by optimizing cam surface geometry parameters, including curvature radii, profile angles, and follower positioning. These parameter changes enable the system to cut off back torque at optimally low values that prevent engine brake overload, avoiding slip and hopping while maintaining adequate torque transmission for normal operation.
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 ball cam mechanism reduces working resistance, enabling the friction clutch to maintain a half-clutch state and effectively cut off smaller back torque values, improving motorcycle stability and reducing driver burden during severe operations.
Implementation Method 1
a ball cam working mechanism, allowing a ball to roll and move the first rotor apart from the second rotor
Implementation Method 2
The ball cam mechanism reduces working resistance
Data Source
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AI summary
A friction clutch (1) includes an input member (2), a friction clutch mechanism (7), a first rotor (21), a back torque limiter mechanism (25), and a second rotor (23). The friction clutch mechanism (7) includes a plurality of friction discs (8, 11), and a pressure plate (12) that presses the friction discs (8, 11). The back torque limiter mechanism (25) includes cam grooves (44) on the first rotor (21) side, cam grooves (45) on the second rotor (23) side, and balls (41) between the cam grooves (44, 45). The cam grooves (44, 45) include hemispherical fitting portions (47, 51) and inclined cam portions (48, 52). The balls (41) move from the fitting portions (47, 51) to the inclined cam portions (48, 52), and an end (61) of the first rotor (21) presses the pressure plate (12) in a direction opposite to the friction discs (8, 11).