Engine Subchamber Ignition Timing Control Under High EGR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine systems with main and subchambers face challenges in achieving optimal fuel efficiency and emission performance due to complications in fuel injection and combustion timing, especially under high EGR conditions.
Innovation Solution
The engine system incorporates a control device that adjusts the ignition timing of the subspark plug relative to the main spark plug, increasing the ignition phase difference under high EGR conditions, and utilizes an EGR device to recirculate exhaust gases, ensuring appropriate combustion in both the main and subchambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fuel is injected only to the main combustion chamber, then the structure is simplified and cost is reduced, but the fuel may not be fully introduced into the subchamber and combustion in the subchamber may be insufficient
Solution Approach 1:
The combustion chamber is segmented into a main combustion chamber and a subchamber separated by a partition with communication holes. This segmentation allows the fuel injected into the main combustion chamber to be distributed to both chambers through controlled communication, ensuring reliable combustion in the subchamber while maintaining a simplified single-injector structure.
Solution Approach 2:
The partition with communication holes acts as an intermediary structure between the main combustion chamber and the subchamber. It controls the flow of fuel-air mixture from the main chamber to the subchamber, enabling reliable subchamber combustion without requiring a separate fuel injection system for the subchamber.
2Device complexity
If the ignition timing of the subspark plug is the same as the main spark plug, then the combustion process is simplified, but under high EGR conditions the mixture gas may not be sufficiently pushed into the subchamber for appropriate combustion
Solution Approach 1:
The ignition timing of the subspark plug is made dynamic and adjustable relative to the main spark plug. Under high EGR conditions, the subignition timing is retarded (set later) to allow sufficient time for the pressure increase in the main combustion chamber to push the fuel-air mixture into the subchamber through the communication holes, ensuring reliable combustion.
Solution Approach 2:
The ignition timing parameter of the subspark plug is changed based on EGR conditions. By retarding the subignition timing under high EGR conditions, the system adapts to the reduced mixture flow into the subchamber, maintaining reliable combustion performance across varying operating conditions.
3Reliability
If the ignition phase difference is increased under high EGR conditions, then combustion in the subchamber is improved, but the control system becomes more complex
Solution Approach 1:
The control device monitors EGR conditions and adjusts the ignition phase difference between the main and subspark plugs accordingly. This feedback mechanism automatically increases the ignition phase difference under high EGR conditions to ensure proper subchamber combustion, while maintaining simpler timing under normal conditions, thus balancing reliability and control complexity.
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 proper combustion in the subchamber, even under high EGR conditions, by leveraging the pressure increase in the main combustion chamber to push mixture gas into the subchamber.
Implementation Method 1
an injector that injects fuel into the main combustion chamber
Implementation Method 2
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
Implementation Method 3
an exhaust gas recirculation (EGR) device that recirculates part of exhaust gas discharged from the cylinder to an intake passage through which intake air introduced into the cylinder circulates
Implementation Method 4
the mixture gas, which is formed inside the main combustion chamber, and is comprised of fuel injected from the main fuel injection valve, and air, is first ignited by the main chamber spark plug
Implementation Method 5
by leveraging the pressure increase in the main combustion chamber to push mixture gas into the subchamber
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An engine system is provided, which includes 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, an exhaust gas recirculation (EGR) device and a control device. In a specific range where EGR is performed, the ignition devices are controlled so that a subignition timing is retarded from a main ignition timing, and an ignition phase difference that is a retard amount of the subignition timing from the main ignition timing becomes larger under a high EGR condition than a low EGR condition, the EGR conditions being conditions in the specific range where engine speeds are the same and EGR rates are different, and the high EGR condition being larger in the EGR rate than the low EGR condition.