Variable Valve Timing Eccentric Cam Mechanism

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Solution Overview

Problem

Current variable valve timing systems for internal combustion engines are either complex and expensive or not well-suited for small engines, such as those in lawn mowers and other appliances, lacking a simple and cost-effective solution for adjusting valve timing.

Innovation Solution

A variable valve timing apparatus that includes a timing shaft with eccentrics, timing control members, and arms cooperating with the camshaft to adjust the timing of cylinder valves by rotating the timing shaft, allowing for angular movement of follower portions to alter valve timing relative to a reference timing, thereby enabling adjustable valve timing without the need for complex mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If independent lifter control by electrical solenoids or rocker arm pivot point changing is used, then valve timing adjustment capability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvevalve timing adjustment capabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple valve timing control functions into a single integrated cam mechanism. The cam profile directly controls the follower to adjust valve timing, eliminating the need for separate electrical solenoids for each cylinder and simplifying the overall control system architecture.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces complex electrical solenoid-based mechanical control systems with a purely mechanical cam-follower mechanism. The cam profile geometry directly translates rotational position into valve timing adjustment, eliminating electrical components and reducing system complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If complex variable valve timing systems are implemented, then valve timing control precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improvevalve timing control precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent achieves valve timing precision by varying the cam profile geometry parameters. Different cam profiles with specific radii, angles, and curvature characteristics directly control the follower motion, providing precise timing adjustment without complex manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The cam mechanism is designed with separable components including the cam body, follower, and adjustable elements that can be manufactured independently using standard machining processes, then assembled to achieve the desired timing precision.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If traditional variable valve timing mechanisms are used, then valve timing adjustability is improved, but suitability for small engines deteriorates

Engineering Contradiction:

Improvevalve timing adjustabilityVSAvoidmechanism size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The cam mechanism is designed to fit within the existing engine structure, with the follower and cam components nested within the valve train housing. The compact arrangement allows the timing adjustment mechanism to be integrated into the limited space available in small engine designs.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The cam-follower mechanism serves multiple functions: it provides valve timing adjustment, maintains valve train geometry, and can be adapted to different valve configurations. This multi-functionality reduces the need for additional components in small engine applications.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The solution provides a simple, cost-effective means to adjust valve timing, improving fuel efficiency, reducing emissions, and optimizing engine torque by allowing for advanced or retarded valve timing based on engine speed and load conditions, thus enhancing engine performance across various operating conditions.

Implementation Method 1

a timing shaft rotatable about a timing shaft axis and comprising a first eccentric

Methodology Applied

Scientific EffectEccentric: Eccentric

Data Source

PatentUS9133735B2Variable valve timing apparatus and internal combustion engine incorporating the same

Publication Date: 2015.09.15 DISCOVERY ENERGY LLC

AI summary

A variable valve timing apparatus, and internal combustion engine incorporating the same, that allows the timing of the opening and/or closing of intake and/or exhaust cylinder valves to be altered relative to a reference timing. As a result, the timing of the valve event can be adjusted relative to a phase of the crankshaft and/or the cycle of the pistons.