Adjustable CVT Flyweights for Low- and High-RPM Torque Tuning
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Solution Overview
Problem
CVT clutch systems with turbocharged engines face a tradeoff between higher horsepower output at low RPMs and mid-to-high RPM ranges due to the traditional method of tuning flyweights, which affects torque distribution and gear shifting efficiency.
Innovation Solution
The design of flyweights with a first coupler for selectively adding mass distal from the cam surface and a second coupler for adding mass proximal to the cam surface, allowing for the adjustment of the center of mass to optimize torque distribution and engagement characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If mass is added to the flyweight to increase centrifugal force at high RPM, then force output at high RPM is improved, but torque output at low RPM deteriorates
Solution Approach 1:
The flyweight mass is segmented into two distinct components: a base mass integrated into the flyweight body and an adjustable mass that can be selectively added or removed. This segmentation allows independent optimization of low RPM torque (base mass) and high RPM force (adjustable mass), resolving the contradiction between force output at high RPM and torque output at low RPM.
Solution Approach 2:
The flyweight system transitions from a static mass configuration to a dynamic, adjustable mass configuration. The adjustable mass can be repositioned or removed based on operating conditions, enabling the system to adapt between prioritizing low RPM torque and high RPM force output, thus resolving the performance tradeoff.
2Productivity
If flyweight mass is increased to improve high RPM engagement, then gear shifting efficiency at high RPM is improved, but acceleration performance at low RPM deteriorates
Solution Approach 1:
By segmenting the mass into base and adjustable components, the system can optimize acceleration performance at low RPM using only the necessary base mass, while reserving the adjustable mass to enhance gear shifting efficiency at high RPM without compromising low RPM performance.
Solution Approach 2:
The system changes the mass parameter dynamically by adding or removing the adjustable mass component. This allows optimization of acceleration performance (lower effective mass at low RPM) and gear shifting efficiency (higher effective mass at high RPM) at different operating conditions, resolving the contradiction between these two performance metrics.
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
This configuration enables fine-tuning of the flyweight's mass and center of mass location, improving torque output and gear shifting efficiency across various RPM ranges, particularly enhancing engine performance in turbocharged engines.
Implementation Method 1
the centrifugal force (i.e., inertia) acting on the flyweights 22 may be sufficient to apply a force to the spider assembly 18 via the interface between the cam surface 26 and the rollers 28 to overcome the biasing force of the spring 20
Implementation Method 2
a spring 20 is positioned on the output shaft 14 to provide a biasing force on the movable sheave 16 away from the stationary sheave 12
Data Source
AI summary
A flyweight comprises a body. The body of the flyweight comprises a pivot, a cam surface, and a first coupler. The first coupler is configured to selectively couple at least one first weight to the body distal from the cam surface. A flyweight comprises a body having at least 20% of its mass positioned to contribute negative torque about a pivot related to an acceleration of a CVT clutch from an idling condition. A method of tuning a flyweight comprises attaching at least one first weight to a first coupler of a body of the flyweight distal from a cam surface of the body. A CVT clutch comprises at least one flyweight with a first coupler configured to selectively couple at least one first weight to a body of the flyweight distal from a cam surface.