Variable Valve Mechanism Cam Sprocket Link Member Phase Control

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Solution Overview

Problem

The existing variable valve mechanism for automatic two-wheeled vehicles requires complex fine adjustments due to high resistance from centrifugal weights, making it difficult to smoothly change the phase of the camshaft in response to engine rotation speed.

Innovation Solution

A variable valve mechanism that includes a cam sprocket, a camshaft integrated with intake or exhaust cams, and a link member that engages with the cam sprocket to transmit rotation, allowing the camshaft to rotate relative to the sprocket, thereby reducing operational resistance and enabling smoother phase changes without the need for complex adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a centrifugal weight is sandwiched between the first driven member and the second driven member to change the cam shaft phase, then the valve timing can be adjusted in response to engine speed, but the resistance generated by the centrifugal weight operation becomes large, requiring complex fine adjustment of the urging force

Engineering Contradiction:

Improvevalve timing adjustment capabilityVSAvoidadjustment mechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention extracts the centrifugal weight from the sandwiched position between driven members and relocates it to the cam shaft itself. This eliminates the need for complex urging force adjustments while maintaining the ability to change cam shaft phase in response to engine speed, as the centrifugal weight directly rotates with the cam shaft rather than being compressed between components.

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If a centrifugal weight is sandwiched between driven members to achieve phase change, then valve timing control is possible, but the operational resistance becomes large, making smooth phase change difficult

Engineering Contradiction:

Improvephase change capabilityVSAvoidsmoothness of phase change

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

By extracting the centrifugal weight from the sandwiched configuration and attaching it directly to the cam shaft, the invention eliminates the resistance generated by compression between driven members. This allows the cam shaft phase to change smoothly in response to engine speed variations without the mechanical binding caused by the previous arrangement.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using the centrifugal weight to push against driven members to achieve phase change, the invention inverts the approach by having the centrifugal weight rotate with the cam shaft and use its radial position to directly control the phase. This inversion eliminates the resistance problem while maintaining the adaptive phase control function.

Inventive Principle:

Principle #13The other way round (Inversion)

3Speed

If the second driven member is displaced relatively to the first driven member by centrifugal force, then the cam shaft phase can be changed, but complex fine adjustment of urging force is required to overcome the resistance

Engineering Contradiction:

Improvecam shaft phase response speedVSAvoidurging force adjustment complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The invention removes the need for complex urging force adjustment mechanisms by extracting the centrifugal weight from the driven member interface. The cam shaft phase response to engine speed changes is achieved directly through the centrifugal weight's rotation, eliminating the intermediate urging force adjustment system while maintaining rapid response capability.

Inventive Principle:

Principle #2Taking out (Extraction)

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 allows for stable and easy phase changes of the camshaft with reduced operational resistance, simplifying the adjustment process and improving responsiveness to engine rotation speed without requiring a special control mechanism.

Implementation Method 1

the link member swings in response to a change in rotation speed of the cam sprocket so as to rotate the cam shaft relatively to the cam sprocket

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentUS10364709B2Variable valve mechanism, engine, and automatic two-wheeled vehicle

Publication Date: 2019.07.30 SUZUKI MOTOR CORP

AI summary

The present invention is capable of more smoothly changing a phase of a cam shaft in a rotation direction. A variable valve mechanism changes an opening/closing timing of an intake valve or an exhaust valve in response to an engine rotation speed. The variable valve mechanism includes: a cam sprocket which rotates in response to a rotation of a crank shaft; an intake cam shaft which is integrated with an intake cam and is provided to be rotatable relatively to the cam sprocket; and a link member that transmits a rotation from the cam sprocket to the intake cam shaft. The link member is supported by the cam sprocket to be swingable and swings in response to a change in rotation speed of the cam sprocket to rotate the intake cam shaft relatively to the cam sprocket.