Engine Combustion Control for Torque Shock Reduction
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Solution Overview
Problem
Engine systems with main and subchambers face torque shocks when transitioning from compression self-ignition to flame propagation combustion due to delayed air-fuel ratio reduction, leading to inadequate flame propagation and decreased engine torque.
Innovation Solution
An engine system with a control device that manages the ignition and air-fuel ratio by suspending main ignition and subignition in a high air-fuel ratio range, then controlling the subspark plug and main spark plug to initiate subignition first and synchronize or delay main ignition, ensuring flame propagation from the subchamber to the main chamber, thereby stabilizing combustion and reducing torque shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If compression self-ignition combustion is used to improve fuel efficiency, then fuel efficiency is improved, but torque shock occurs when transitioning to flame propagation combustion
Solution Approach 1:
The patent dynamically switches between compression self-ignition combustion and flame propagation combustion modes based on operating conditions. The control device selects the appropriate combustion mode according to engine load and speed, enabling adaptive optimization of fuel efficiency while managing torque characteristics through mode transition rather than fixed operation
Solution Approach 2:
The patent changes combustion parameters (ignition method, air-fuel ratio, injection timing) to transition between combustion modes. By adjusting these parameters, the system achieves compression self-ignition for fuel efficiency improvement while controlling the transition process to minimize torque shock through coordinated parameter modification
2Speed
If jump spark ignition is performed immediately after transition to reduce air-fuel ratio, then flame propagation combustion should be achieved, but torque decreases due to delayed air-fuel ratio reduction
Solution Approach 1:
The patent performs preliminary action by pre-adjusting the air-fuel ratio before transition to flame propagation combustion. The control device modifies intake air amount or fuel injection quantity in advance to ensure the air-fuel ratio is reduced to the appropriate level before ignition occurs, preventing torque decrease caused by delayed ratio adjustment
Solution Approach 2:
The patent uses feedback control to monitor actual air-fuel ratio and combustion characteristics, then adjusts ignition timing and air-fuel ratio accordingly. The control device receives feedback from sensors and modifies combustion parameters to maintain optimal torque output during the transition from compression self-ignition to flame propagation combustion
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 by maintaining flame propagation in the main chamber, even with high initial air-fuel ratios, and prevents torque decreases by ensuring consistent combustion after transitioning to a lower air-fuel ratio range.
Implementation Method 1
a subspark plug that performs a subignition for the igniting mixture gas inside the subchamber, a main spark plug that performs a main ignition for igniting mixture gas inside the main combustion chamber
Implementation Method 2
suspend the main ignition and the subignition to carry out compression self-ignition combustion of the mixture gas inside the main combustion chamber
Implementation Method 3
an injector that injects fuel into the main combustion chamber
Implementation Method 4
flame generated in the subchamber is blown off to the main combustion chamber, the combustion speed in the main combustion chamber can be increased
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, and a subspark plug that ignites the mixture gas inside the subchamber, an throttle valve, and a control device. In a first range, compression self-ignition combustion of the mixture gas inside the main combustion chamber is performed. In a second range, flame propagation combustion is performed while setting an air-fuel ratio of the mixture gas lower than that in the first range. Immediately after the transition from the first range to the second range, only the subignition is performed, or the subignition and the main ignition are performed while setting a timing of the main ignition to a timing same as or retarded from the subignition.