SPCCI Engine Combustion Control for Noise and Efficiency
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Solution Overview
Problem
In engines that perform compression autoignition, pressure variations during ignition can lead to increased combustion noise, and as engine speed increases, the ignition timing of compression ignition combustion tends to be delayed, reducing efficiency and output torque.
Innovation Solution
A combustion mode called SPCCI (Spark Controlled Compression Ignition) is introduced, where Spark Ignition (SI) combustion and Compression Ignition (CI) combustion are combined. SI combustion forcibly ignites the air-fuel mixture, increasing chamber temperature for autoignition, and the state quantity setting device adjusts the temperature by controlling fresh air, burned gas, and residual gas to maintain optimal conditions, ensuring timely autoignition and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If compression autoignition is performed to improve fuel economy, then fuel economy is improved, but combustion noise increases due to pressure variation at ignition
Solution Approach 1:
The patent combines Spark Ignition (SI) and Compression Ignition (CI) into a hybrid combustion mode called SPCCI. The spark plug initiates combustion to control pressure rise rate and reduce noise, while compression heating enables autoignition for fuel economy. This merging allows the system to achieve both low noise and high efficiency by utilizing the advantages of both combustion modes simultaneously.
Solution Approach 2:
The patent controls combustion parameters by adjusting ignition timing of the spark plug and managing in-cylinder temperature and pressure conditions. By optimizing these parameters, the system achieves controlled combustion that reduces pressure variation noise while maintaining the efficiency benefits of compression ignition.
2Productivity
If engine speed is increased to improve productivity, then output increases, but ignition timing of compression ignition is delayed reducing efficiency
Solution Approach 1:
The patent uses the spark plug to perform preliminary ignition action before compression autoignition would naturally occur. This advance ignition ensures that combustion starts at the optimal timing regardless of engine speed, preventing delay and maintaining efficiency even at high rotational speeds where compression heating alone would be insufficient.
Solution Approach 2:
The patent dynamically adjusts the combustion mode based on engine operating conditions. At higher engine speeds where compression ignition timing would be delayed, the system relies more on spark ignition to maintain proper timing, while at lower speeds compression ignition plays a larger role, creating a dynamic adaptation to engine speed variations.
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
SPCCI combustion effectively reduces combustion noise and improves fuel economy by controlling ignition timing and maintaining a high-temperature environment for autoignition, ensuring efficient engine operation across varying engine speeds.
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
heat generation by the SI combustion increases the temperature in the combustion chamber, to combust unburned air-fuel mixture by autoignition
Data Source
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AI summary
A control apparatus for an engine includes an engine (1), a state quantity setting device (23, 24, 43, 48, 54, 551, 552, 56), a spark plug (25), and a controller (ECU 10). After the spark plug ignites air-fuel mixture to start combustion, combustion of unburned air-fuel mixture is caused by autoignition. The controller outputs a control signal to the state quantity setting device such that, when a number of revolutions of the engine is high, a temperature in a combustion chamber before start of compression is higher than that when the number of revolutions of the engine is low.