Dual Ignition Engine Combustion Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Engines with a main combustion chamber and a subchamber face challenges in fuel efficiency and emission performance, particularly in low-speed high-load and high-speed high-load operating ranges, due to insufficient flame supply and potential knocking, when the fuel injection device is only disposed in the main combustion chamber.
Innovation Solution
An engine system with a cylinder block, cylinder head, piston, main combustion chamber, subchamber, fuel injector, main spark plug, subspark plug, and a controller that adjusts ignition timings and phases to ensure proper fuel injection and combustion in both chambers, particularly by performing main ignition followed by subignition in low-speed high-load conditions and preceding subignition in high-speed high-load conditions to prevent knocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the fuel injection device is disposed only at the main combustion chamber to simplify the structure, then the device complexity is reduced, but the combustion performance in high-load ranges deteriorates due to insufficient flame supply and potential knocking
Solution Approach 1:
The combustion chamber is segmented into a main combustion chamber and a subchamber separated by a partition with communicating holes. The subchamber contains a sub-spark plug while the main chamber has the fuel injector and main spark plug. This segmentation allows independent ignition control in each chamber, enabling the subchamber to provide additional flame sources for improved combustion reliability in high-load conditions while maintaining a relatively simple overall structure.
Solution Approach 2:
The sub-spark plug performs preliminary ignition in the subchamber before the main combustion occurs in the main chamber. By igniting the air-fuel mixture in the subchamber first, flame is generated and then transferred to the main combustion chamber through the communicating holes, providing an early flame source that improves combustion stability and prevents knocking during high-load operation.
2Productivity
If the subignition is performed after the main ignition in low-speed high-load range, then the combustion speed in subchamber is improved by overlapping combustion pressure with piston pushing force, but the ignition timing control complexity increases
Solution Approach 1:
The ignition timing control system dynamically adjusts the timing of main ignition and subignition based on engine operating conditions. In low-speed high-load range, the controller sets subignition to occur after main ignition to utilize combustion pressure overlap with piston pushing force for enhanced flame propagation. In high-speed ranges, the control strategy changes to prevent knocking. This dynamic adaptation optimizes combustion speed across different operating conditions.
Solution Approach 2:
The controller changes the ignition timing parameters based on engine speed and load conditions. For low-speed high-load operation, the subignition timing is set subsequent to main ignition timing to maximize combustion speed through pressure overlap. For high-speed operation, the timing parameters are adjusted differently to suppress knocking. This parameter adjustment strategy resolves the contradiction between combustion speed and control complexity.
3Object-affected harmful factors
If the subignition is performed before or simultaneously with main ignition in high-speed high-load range, then knocking is suppressed by earlier combustion, but the flame blow-off intensity from subchamber may be insufficient
Solution Approach 1:
The system dynamically adjusts ignition timing strategy based on engine speed. In high-speed high-load ranges where knocking is a concern, the controller advances the subignition timing to occur before or simultaneously with main ignition, ensuring earlier combustion starts that suppress knocking. The communicating holes between chambers facilitate flame transfer, and the partition design maintains sufficient flame blow-off intensity even with advanced timing.
Solution Approach 2:
The sub-spark plug performs preliminary ignition in the subchamber before the main combustion event. This preliminary action generates flame in the subchamber that then transfers to the main combustion chamber through communicating holes, providing an early combustion start that suppresses knocking while maintaining adequate flame intensity through the chamber communication design.
4Loss of energy
If the main ignition and subignition are both performed to combust unburnt mixture gas, then the fuel efficiency and emission performance are improved, but the device complexity increases due to additional spark plug and control system
Solution Approach 1:
The ignition system is segmented into two independent but coordinated systems: a main spark plug for primary combustion and a sub-spark plug for secondary combustion in the subchamber. This segmentation allows the subchamber to capture and combust unburnt mixture gas that escapes from the main chamber, improving fuel efficiency and reducing emissions. The modular design adds functionality while keeping each ignition unit relatively simple.
Solution Approach 2:
The dual ignition system ensures continuous useful combustion action. The main spark plug initiates primary combustion, and the sub-spark plug continues the combustion process by igniting any unburnt mixture in the subchamber. This continuous action ensures complete fuel combustion across different operating conditions, improving fuel efficiency and emission performance without requiring overly complex control mechanisms.
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 configuration enhances fuel efficiency and emission performance by ensuring adequate combustion in both chambers, reducing unburnt mixture gas and suppressing knocking, while optimizing fuel injection and ignition timings based on engine speed and load.
Implementation Method 1
a subspark plug that performs subignition for igniting the mixture gas inside the subchamber
Implementation Method 2
a main spark plug that performs main ignition for igniting a mixture gas inside the main combustion chamber
Implementation Method 3
an injector that injects fuel into the main combustion chamber
Implementation Method 4
the force of pushing the mixture gas into the subchamber becomes weaker because the piston moves slowly
Implementation Method 5
combusting the mixture gas inside the subchamber to blow off flame inside the subchamber to the main combustion chamber
Data Source
AI summary
An engine system is provided, which includes a cylinder block, a cylinder head, a piston, a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, a subspark plug that ignites the mixture gas inside the subchamber, and a controller electrically connected to the injector, the main spark plug and the subspark plug. When an engine load is above a given reference load, the controller controls, in a low-speed range below a given reference engine speed, the ignition devices so that the subignition is performed after the main ignition, and the controller controls, in a high-speed range exceeding the reference engine speed, the ignition devices so that only the subignition is performed, or so that the main ignition is performed at the same timing as or after the subignition.