CVT Belt Flutter Prevention via Throttle-Triggered Flange Tensioning

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Solution Overview

Problem

In electronically-controlled belt-type continuously variable transmissions, the belt tends to flutter at startup due to lack of initial belt pressing force, causing rider discomfort and noise, unlike mechanical systems where centrifugal force ensures a constant belt tension.

Innovation Solution

A controller and actuator system that detects throttle opening and vehicle speed, moving the movable flange of the primary sheave to decrease its groove width at startup, applying tension to the belt and preventing fluttering, similar to mechanical systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the movable flange is held at the low position with maximum groove width until vehicle speed exceeds a specified value, then the electric motor does not work and energy consumption is reduced, but the belt becomes slack and flutters causing vibration and noise

Engineering Contradiction:

Improveelectric motor energy consumptionVSAvoidbelt fluttering, vibration, and noise

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The controller performs preliminary action by detecting when the throttle opening degree switches from closed to open state, and proactively moves the movable flange to apply belt pressing force before the vehicle starts moving. This preliminary tensioning prevents belt fluttering during acceleration without requiring continuous motor operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies belt pressing force periodically rather than continuously - specifically when the throttle transitions from closed to open state. The controller monitors throttle position and applies tension only during startup acceleration phases, reducing overall energy consumption while preventing fluttering when needed

Inventive Principle:

Principle #19Periodic action

2Object-affected harmful factors

If the movable flange is moved to decrease groove width at startup to apply belt pressing force, then belt fluttering is prevented, but the electric motor must work continuously increasing energy consumption

Engineering Contradiction:

Improvebelt fluttering preventionVSAvoidelectric motor energy consumption

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The system applies belt pressing force preliminarily at startup when the throttle opens, ensuring the belt is tensioned before fluttering can occur. After this preliminary action, the motor stops working until vehicle speed exceeds the specified value, minimizing energy consumption while maintaining belt stability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller applies preliminary anti-action by detecting throttle opening and moving the movable flange to create belt pressing force that counteracts the potential fluttering motion before it can occur during acceleration

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If the movable flange remains fixed at low position during startup, then the transmission structure is simple and reliable, but the belt cannot follow slackening motion and fluttering occurs

Engineering Contradiction:

Improvetransmission system simplicity and reliabilityVSAvoidbelt fluttering due to inability to follow slackening motion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system transitions from a static fixed position to a dynamic adjustable position. The movable flange is held at the low position during normal operation for simplicity, but becomes dynamically adjustable when the throttle opens, allowing it to move and apply belt pressing force only when needed to prevent fluttering

Inventive Principle:

Principle #15Dynamics

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

Prevents belt fluttering at startup by applying a load to the belt, reducing vibrations and noise, ensuring smooth vehicle acceleration.

Implementation Method 1

the actuator regulates a groove width of the primary sheave by controlling motion of the movable flange

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

A throttle opening degree sensor detects an opening degree of a throttle, and outputs to the controller a signal produced at least when the throttle opening degree is switched from a closed state to an open state

Methodology Applied

Scientific EffectSensor detection:

Implementation Method 3

A V-belt is routed around the primary and secondary sheaves and continuously changes a transmission ratio

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8439797B2Continuously variable transmission

Publication Date: 2013.05.14 YAMAHA MOTOR CO LTD

AI summary

A straddle-type vehicle that prevents belt fluttering motion when the vehicle starts. A throttle opening degree sensor that detects an opening degree of a throttle is connected to and outputs to a controller a signal produced when the throttle opening degree switches from a closed state to an open state. When the vehicle starts from a standing state, the controller controls an actuator, according to the signal produced when the throttle opening degree switches from the closed state to the open state, to move a movable flange from a normal position in the standing state in a direction to narrow the groove width of a primary sheave.