Compression Auto-Ignition Engine Control via Spark-Assisted Combustion
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Solution Overview
Problem
In combustion by compression autoignition, increased fuel supply leads to pressure variations and combustion noise, causing discomfort for occupants.
Innovation Solution
A combustion mode combining Spark Ignition (SI) and Compression Ignition (CI) is introduced, where SI combustion initiates flame propagation and heat generation to enhance temperature, controlling CI combustion through SI combustion, with divided fuel injection and adjusted ignition timing to manage temperature variations and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the amount of fuel supplied into the combustion chamber increases, then combustion efficiency is improved, but pressure variation at ignition increases and combustion noise increases
Solution Approach 1:
The fuel injection is divided into multiple stages: a first injection of pilot fuel before compression top dead center to initiate controlled combustion, and a second injection of main fuel after compression top dead center to complete combustion. This segmentation allows the combustion process to proceed in a controlled manner, maintaining efficiency while reducing pressure variations and combustion noise.
2Loss of energy
If compression autoignition is used, then fuel economy is improved, but combustion noise increases due to uncontrolled autoignition
Solution Approach 1:
A spark plug is introduced as an intermediary device to initiate combustion at a controlled timing before compression top dead center. This allows the combustion process to start in a controlled manner rather than through uncontrolled autoignition, reducing pressure variations and combustion noise while maintaining the fuel economy benefits of compression ignition.
Solution Approach 2:
Pilot fuel is injected before compression top dead center to create a controlled combustion event that raises the temperature of the compressed charge. This preliminary action prepares the combustion chamber for the main fuel injection, enabling efficient combustion while controlling the ignition process to reduce noise.
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 effectively suppresses combustion noise while maintaining efficient combustion, enhancing fuel economy and exhaust gas performance by controlling CI combustion through SI combustion.
Implementation Method 1
a spark plug forcibly ignites air-fuel mixture in a combustion chamber, to combust the air-fuel mixture by flame propagation
Implementation Method 2
combust the air-fuel mixture by flame propagation
Implementation Method 3
heat generation by the SI combustion enhances the temperature in the combustion chamber, to combust unburned air-fuel mixture by autoignition
Implementation Method 4
compression autoignition of air-fuel mixture
Implementation Method 5
The controller controls the injector so that fuel is injected by a plurality of divided injections
Data Source
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AI summary
A control apparatus for a compression autoignition engine (1) controls compression autoignition by ignition. The control apparatus includes an injector (6), a spark plug (25), and a controller (10). The controller (10) controls the injector (6) so that fuel is injected by a plurality of divided injections, and thereafter, outputs a control signal to the spark plug (25) at predetermined ignition timing so that, by ignition, unburned air-fuel mixture combusts by autoignition. Control is performed so that, when load on the engine (1) is high, an amount of fuel injected at later timing among the plurality of injections becomes larger than when the load is low.