SPCCI Engine Control Combustion Noise and Fuel Economy
Solution Overview
Problem
Existing engine technologies face challenges in controlling compression autoignition timing and thermal efficiency, leading to suboptimal fuel economy and increased combustion noise.
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, allowing the spark plug to forcibly ignite the air-fuel mixture, followed by autoignition, with the heat generation from SI combustion controlling the autoignition timing and adjusting the heat amount ratio to optimize fuel economy and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If compression autoignition is used to improve fuel economy, then thermal efficiency is improved, but autoignition timing cannot be controlled precisely and combustion noise increases
Solution Approach 1:
The combustion process is divided into two distinct phases: SI combustion phase where the spark plug ignites the air-fuel mixture and CI combustion phase where compression autoignition occurs. This segmentation allows independent control of each phase, with SI combustion providing controllable flame propagation and CI combustion providing fuel economy benefits through uncontrolled autoignition of remaining mixture.
Solution Approach 2:
The spark plug acts as an intermediary that initiates SI combustion, which then serves as a controlled mechanism to manage the overall combustion process. The SI combustion creates a transition state that enables subsequent CI combustion, mediating between the need for controllable ignition and fuel-efficient autoignition.
2Loss of time
If spark plug ignition timing is advanced to promote autoignition, then combustion timing is improved, but thermal efficiency deteriorates due to excessive flame propagation
Solution Approach 1:
Instead of relying entirely on SI combustion through advanced spark timing, the system uses partial SI combustion to initiate the process and allows the remaining air-fuel mixture to undergo CI combustion. This partial action approach achieves timely combustion start while avoiding the excessive flame propagation that would reduce thermal efficiency.
3Use of energy by moving object
If compression autoignition is used to shorten combustion period for fuel economy, then thermal efficiency is improved, but combustion noise increases due to uncontrolled combustion rate
Solution Approach 1:
The combustion process is divided into two distinct phases: SI combustion phase where the spark plug ignites the air-fuel mixture and CI combustion phase where compression autoignition occurs. This segmentation allows independent control of each phase, with SI combustion providing controllable flame propagation and CI combustion providing fuel economy benefits through uncontrolled autoignition of remaining mixture.
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 precise control of autoignition timing, improving fuel economy while suppressing combustion noise by adjusting the ignition timing and heat generation, ensuring efficient combustion across varying engine loads and temperatures.
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 enhances the temperature in the combustion chamber, to combust unburned air-fuel mixture by autoignition
Implementation Method 3
The CI combustion starts by compression autoignition of air-fuel mixture in a combustion chamber
Data Source
Figure 1
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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), a spark plug (25), and a controller (ECU 10). The spark plug ignites air-fuel mixture at predetermined ignition timing so that unburned air-fuel mixture combusts by autoignition after start of combustion of the air-fuel mixture by the ignition, and the controller adjusts a heat amount ratio in accordance with an operation state of the engine through change of the ignition timing, the heat amount ratio representing an index associated with a ratio of an amount of heat generated when the air-fuel mixture combusts by flame propagation with respect to a total amount of heat generated when the air-fuel mixture combusts in the combustion chamber (17).