Motorcycle CVT Cam Profile for Adaptive Gear Shift Response
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Solution Overview
Problem
Conventional Continuously Variable Transmission (CVT) systems in motorcycles do not adapt to the driver's acceleration or deceleration requirements, as the gear shift curve is fixed and dependent on engine revolutions, failing to facilitate sudden changes in vehicle speed.
Innovation Solution
A CVT transmission system with a cam system between the fixed and mobile bushings, featuring a pin and cam profile that adjusts the gear shift by altering the approach between pulley active surfaces during acceleration and deceleration, allowing for dynamic adaptation of the gear ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional CVT system with fixed physical and geometrical characteristics is used, then the transmission ratio depends only on engine revolutions, but the system cannot adapt to sudden acceleration or deceleration requests from the driver
Solution Approach 1:
The patent applies the Dynamics principle by introducing a mobile bushing with a cam profile that can dynamically adjust the gear shift curve based on driver requests. The cam profile allows the transmission system to transition from a fixed state to a dynamic state where the effective radius ratio between pulleys can be modified in real-time, enabling adaptation to acceleration or deceleration demands without requiring a completely new control system architecture
Solution Approach 2:
The patent implementsParameter changes by modifying the effective radius of the pulleys through the cam profile mechanism. By changing the geometric parameters of the pulley system (specifically the effective radius ratio) in response to driver input, the transmission can alter its gear shift characteristics. This allows the same physical system to operate with different transmission curves, improving adaptability without adding complex electronic control systems
2Speed
If the gear shift curve is fixed based on engine revolutions, then the transmission system is simple to control, but it fails to facilitate sudden changes in vehicle speed
Solution Approach 1:
The patent uses an intermediary mechanism (the cam profile on the mobile bushing) that translates driver requests into mechanical adjustments of the transmission ratio. This intermediary allows the driver's input to be converted into smooth mechanical motion that adjusts the pulley effective radii, enabling fast speed response while maintaining mechanical simplicity and ease of operation without requiring complex electronic control
3Adaptability or versatility
If a cam system with pin and cam profile is added to adjust gear shift, then the transmission can adapt to acceleration and deceleration requests, but stress concentrations may occur in the cam profile
Solution Approach 1:
The patent applies the Spheroidality (Curvature) principle by designing the cam profile with carefully engineered curved surfaces. The cam profile's geometric shape is optimized to distribute contact stresses evenly across the contact area between the pin and cam surface. This curvature design prevents stress concentrations that would otherwise occur at sharp edges or flat surfaces, maintaining the strength of the cam profile while enabling gear shift adaptability
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 the transmission system to accommodate driver requests for acceleration or deceleration, providing a more responsive and sporting behavior compared to standard CVT systems, with the ability to shape the response to acceleration or deceleration demands and reduce stress concentrations.
Implementation Method 1
a cam system between the fixed and mobile bushings, featuring a pin and cam profile that adjusts the gear shift by altering the approach between pulley active surfaces
Implementation Method 2
the drive pulley comprises a speed regulator made with centrifugal masses, generically referred to as 'rollers', which have the task of realizing the axial drawing together of the respective half-pulleys
Data Source
AI summary
A continuously variable transmission device (1) for a two-wheel, three-wheel or four-wheel motorcycle includes a cam system (20, 22; 32a, 32b) operating between a fixed bushing (11) and a mobile bushing (9). The device is configured to obstruct the approach between the active surfaces (8a, 10a) or to facilitate the approach of the active surfaces.