Variable Compression Ratio Engine Control for Fuel Injection Timing
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Solution Overview
Problem
In high load regions of internal combustion engines, existing direct injection systems face challenges in maintaining a long fuel injection period without excessive retarding of the end timing, leading to smoke generation and decreased measurement accuracy due to fuel collision and adhesion on the piston, especially when using high injection rates.
Innovation Solution
A control device with a variable compression ratio mechanism, such as a multi-link piston crank mechanism, sets the fuel injection start timing before the exhaust upper dead center, allowing a longer injection period while suppressing smoke generation by maintaining a low compression ratio and reducing the relative speed of the piston, thus enabling the use of a fuel injection valve with a small injection rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the fuel injection start timing is set closer to the exhaust upper dead center, then the injection period becomes longer, but smoke is increased by the collision and adhesion of the fuel on the piston
Solution Approach 1:
The patent applies a variable compression ratio mechanism that dynamically changes the piston position and movement characteristics. By varying the compression ratio, the piston rising speed near the upper dead center is reduced, which decreases the collision and adhesion of injected fuel on the piston surface, thereby suppressing smoke generation even when the injection period is extended.
Solution Approach 2:
The patent changes the compression ratio parameter to optimize fuel injection characteristics. By controlling the compression ratio to a low value in the high load region, the system enables longer injection periods without the harmful effects of fuel adhesion on the piston, as the altered piston motion parameters reduce the intensity of fuel-piston interaction.
2Reliability
If the injection rate of the fuel injection valve is increased, then the fuel evaporation and mixture are improved, but the injection period becomes excessively short when the fuel injection amount is small, decreasing measurement accuracy
Solution Approach 1:
The variable compression ratio mechanism creates favorable piston motion dynamics that enhance fuel evaporation and mixture quality even with lower injection rates. The reduced piston rising speed near the upper dead center increases the residence time of fuel in the combustion chamber, improving evaporation and mixing without requiring high injection rates, thereby maintaining measurement accuracy.
3Duration of action of moving object
If the fuel injection end timing is excessively retarded at the high load, then the injection period becomes longer, but it is not possible to ensure the time necessary for the mixture and evaporation of the fuel spraying, deteriorating the combustion
Solution Approach 1:
The variable compression ratio mechanism optimizes the piston motion dynamics during the injection period. By reducing the piston rising speed near the upper dead center, the system extends the effective time for fuel evaporation and mixture formation without excessively retarding the injection end timing, thereby maintaining combustion quality while achieving a longer injection period.
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 allows for a longer injection period without deteriorating combustion, reduces smoke generation, and improves measurement accuracy by using a fuel injection valve with a small injection rate, while maintaining efficient fuel evaporation and mixture formation.
Implementation Method 1
a variable compression ratio mechanism arranged to vary a relative position relationship between a piston and a cylinder, and thereby to vary a mechanical compression ratio
Implementation Method 2
a fuel injection valve arranged to directly inject a fuel within a combustion chamber
Implementation Method 3
the evaporation and the mixture of the fuel is deteriorated
Implementation Method 4
the evaporation and the mixture of the fuel is deteriorated
Implementation Method 5
to ignite a generated mixture air by an ignition plug
Data Source
AI summary
A control device for an internal combustion engine including a variable compression ratio mechanism arranged to vary a relative position relationship between a piston and a cylinder, and thereby to vary a mechanical compression ratio, and a fuel injection valve arranged to directly inject a fuel within a combustion chamber, the control device includes: at least in an engine high load region including a full open, the compression ratio at an exhaust upper dead center being controlled to a low compression ratio, a fuel injection start timing of the fuel in which an air-fuel mixture is formed within the combustion chamber, and which is ignited by an ignition plug being set before an exhaust upper dead center so that a fuel injection period crosses an upper dead center.