Valve Lift Control for Engine Startability

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Solution Overview

Problem

Internal combustion engines face challenges in efficiently managing valve lift modes to optimize fuel vaporization and prevent pre-ignition, engine flare, and noise, especially during temperature variations, as existing systems lack adaptive control mechanisms to adjust compression ratios based on engine temperature.

Innovation Solution

An engine control system that selectively operates intake valves in low lift mode at lower engine temperatures and high lift mode at higher temperatures, using distinct sets of cam lobes to adjust effective compression ratios, thereby enhancing fuel vaporization and minimizing engine issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the engine operates with a high compression ratio at low temperatures, then fuel vaporization is improved, but pre-ignition and engine flare occur at high temperatures

Engineering Contradiction:

Improvefuel vaporizationVSAvoidpre-ignition and engine flare

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The valve lift system dynamically switches between low lift mode (higher compression ratio) and high lift mode (lower compression ratio) based on engine temperature conditions, allowing the compression ratio to adapt to thermal conditions and prevent pre-ignition while maintaining fuel vaporization efficiency

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the valve lift parameter to alter the effective compression ratio, using low lift mode for higher compression at low temperatures and high lift mode for lower compression at high temperatures, thereby controlling combustion characteristics across different thermal states

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the engine uses a fixed compression ratio, then the system structure is simple, but it cannot adapt to temperature variations for optimal performance

Engineering Contradiction:

Improvesystem structureVSAvoidtemperature adaptation

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The camshaft is segmented into multiple cam lobes with different geometric profiles (first set for low lift mode, second set for high lift mode), allowing the valve lift mechanism to select between different compression ratios based on temperature conditions without requiring a completely complex variable geometry system

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The single camshaft serves multiple functions by incorporating different cam lobe profiles that provide both low lift mode operation (for cold conditions requiring higher compression) and high lift mode operation (for hot conditions requiring lower compression), eliminating the need for separate camshafts for different operating conditions

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9488078B2Valve lift control systems and methods for engine startability

Publication Date: 2016.11.08 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A startup/shutdown control module selectively generates an engine startup command when an engine of the vehicle is off. A starter control module applies power to a starter motor when the engine startup command is generated. A valve control module, in response to the generation of the engine startup command: operates intake valves of cylinders of the engine in a low lift mode when an engine temperature is less than a predetermined temperature; and operates the intake valves of the cylinders of the engine in a high lift mode when the engine temperature is greater than the predetermined temperature.