Intake Valve Timing Control for Otto Engine Transient Load

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Solution Overview

Problem

Internal combustion engines, particularly Otto engines, face challenges in thermodynamic efficiency, high fuel consumption, and pollutant emissions during transient operation from part-load to full-load, with conventional methods offering unsatisfactory load absorption and efficiency.

Innovation Solution

The method involves temporarily shifting the intake valve closure time towards the piston's bottom dead center during transient operation, increasing air intake and turbocharger output, while maintaining low fuel consumption and reducing pollutant emissions by adjusting intake valve timing and exhaust gas recirculation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the intake valve is closed very early or very late in Miller mode to increase compression ratio and thermodynamic efficiency, then fuel consumption improves, but the power output and load absorption during transient operation deteriorate

Engineering Contradiction:

Improvefuel consumptionVSAvoidpower output during transient operation

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The valve train system is made dynamically adjustable with at least one intake valve that can be independently controlled to have different closure timings. During transient operation, the intake valve closes at a conventional time to maintain power output, while during steady-state operation it closes early or late to achieve Miller mode efficiency improvements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The valve train is segmented into at least one adjustable intake valve and other fixed valves. This segmentation allows selective adjustment of only the necessary valve(s) to achieve the desired compromise between efficiency and power, while other valves maintain conventional timing for stability.

Inventive Principle:

Principle #1Segmentation

2Temperature

If the fuel-air mixture is enriched in full-load operation to reduce thermal loads on pistons and exhaust parts, then thermal load decreases, but fuel consumption and pollutant emissions increase

Engineering Contradiction:

Improvethermal load on pistons and exhaust partsVSAvoidfuel consumption

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

Instead of changing the fuel-air mixture composition (enrichment), the invention changes the valve timing parameters to control thermal loads. By adjusting when the intake valve closes, the effective compression ratio and cylinder filling are controlled, which manages thermal loads without requiring fuel enrichment.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If the compression ratio is increased in Miller mode to improve thermodynamic efficiency, then fuel economy improves, but the knocking tendency increases

Engineering Contradiction:

Improvethermodynamic efficiencyVSAvoidknocking tendency

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The compression ratio is made dynamically adjustable through variable valve timing. During transient operation when knocking is less of a concern, conventional valve timing is used. During steady-state operation, the intake valve closes early to increase the effective compression ratio for improved efficiency, while the early closure also reduces the temperature and pressure conditions that cause knocking.

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

This approach enables rapid power increase during transient operation with reduced fuel consumption and emissions, improving the engine's efficiency and performance compared to conventional methods.

Implementation Method 1

an exhaust gas turbocharger (2) downstream of the internal combustion engine

Methodology Applied

Scientific EffectTurbine: Turbine

Implementation Method 2

the air charge in the internal combustion engine is compressed with the aid of the exhaust gas turbocharger (2)

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

a partial flow of discharged exhaust gas can be supplied to the combustion air flow as exhaust gas recirculation

Methodology Applied

Scientific EffectExhaust gas recirculation: Convection

Data Source

PatentEP2898207B1Method for controlling the timing of an intake valve of an internal combustion engine

Publication Date: 2016.03.30 MERCEDES BENZ GROUP AG

Figure 1~2

AI summary

The invention relates to a method for operating an internal combustion engine (1), in particular an Otto engine, having at least one inlet valve (11), in which - a charged air stream fed to the internal combustion engine is compressed using a turbocharger (2), - the at least one inlet valve (11) of the internal combustion engine (1) is closed at a very early first time (t1) or at a very late second time (t2) in part-load operation, - the at least one inlet valve (11) is closed at an early third time (t3) or at a late fourth time (t4) during transition from the part-load operation to full-load operation, the third time (t3) succeeding the first time (t1) and the fourth time (t4) preceding the second time (t2).