Motorcycle Clutch Bell Profile for Reverse Engagement
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Solution Overview
Problem
Current transmission systems with automatic speed variation, such as CVTs, in vehicles like motorcycles and scooters, cannot reverse the vehicle with the engine off or start the engine by pushing when it's idling or has a flat battery, due to the clutch mechanism's inability to engage or disengage effectively in reverse rotation.
Innovation Solution
A clutch assembly with a bell and engagement profile that allows alternative engagement and disengagement by rotating transmission components, utilizing a cylindrical portion with specific depressions and pawls that switch between engagement and disengagement positions based on rotation direction, enabling the vehicle to be reversed and started with the engine off by exploiting opposite rotation directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional clutch mechanism is used in CVT systems, then the clutch can engage and disengage effectively in forward rotation, but it cannot engage or disengage effectively in reverse rotation, preventing vehicle reversal with engine off or push-starting
Solution Approach 1:
The clutch bell is designed with an asymmetric engagement profile where the engagement surface has a specific geometric configuration that allows engagement when rotation direction is reversed. The profile includes a ramp surface that engages the pawl in reverse rotation, enabling the clutch to function in both forward and reverse directions differently from traditional symmetric clutch designs
Solution Approach 2:
The engagement profile of the clutch bell is intentionally made asymmetric with respect to rotation direction. The profile geometry differs for clockwise and counter-clockwise rotation, allowing the clutch to engage through different mechanisms depending on rotation direction, thereby enabling reverse operation capability
2Reliability
If the clutch is designed to engage only in forward rotation, then the structure can be simple and reliable, but the vehicle cannot be reversed with engine off or started by pushing
Solution Approach 1:
The clutch mechanism dynamically adapts its engagement behavior based on rotation direction. The asymmetric profile causes the clutch to engage through different geometric features depending on whether rotation is forward or reverse, allowing the same structure to provide reliable engagement in both operational modes without requiring separate clutch mechanisms
3Ease of operation
If a complex clutch mechanism is designed to handle both forward and reverse rotation, then reverse operation becomes possible, but the device complexity and cost increase
Solution Approach 1:
The clutch bell's engagement profile is designed to perform multiple functions with a single structure. The same asymmetric profile enables both forward rotation engagement and reverse rotation engagement, as well as allowing the clutch to remain disengaged when stationary. This multi-functionality eliminates the need for separate engagement mechanisms for different rotation directions, maintaining simplicity while enabling reverse 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
Enables vehicle reversal and push-starting with the engine off, using a minimal number of simple, cost-effective components, while maintaining normal operation by automatically engaging and disengaging the clutch based on rotation direction.
Implementation Method 1
the outward translation (away from the shaft 11) of rollers 18 occurs by virtue of the action of the centrifugal force which acts on them when a predetermined rotation speed of the shaft 11 (and therefore of the pulley 12) is reached
Data Source
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AI summary
A clutch, in particular for motorcycles, said clutch comprising a bell (102) adapted to be alternatively engaged and disengaged by a rotating transmission component (107), wherein the mutual engagement of said bell (102) and said rotating transmission component (107) by means of a first engagement means results in said bell (102) dragged in rotation by said transmission component (107) in a first rotation direction (A), wherein said bell (102) defines an engagement profile formed so as to be alternatively engaged and disengaged by second engagement means (120) dragged in rotation by said transmission component (107), and wherein the mutual engagement of said second engagement means (120) and said engagement profile arises as a result of both the rotation of said transmission component (107) in a second rotation direction, opposite to said first rotation direction (A), and the rotation of said bell (102) in said first rotation direction (A), whereas the mutual disengagement of said engagement means (120) and said engagement profile arises as a result of both the rotation of said transmission component (107) in said first rotation direction (A) opposite to said second rotation direction, and the rotation of said bell (102) in said second rotation direction.