Compression Ignition Engine Control System for Torque Stability
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Solution Overview
Problem
Existing compression ignition engine technologies face challenges in maintaining stable combustion and maximizing thermal efficiency, especially when transitioning between different engine modes, leading to degradation in emission performance and torque stability due to changes in air-fuel ratios.
Innovation Solution
A control system that adjusts fuel and air delivery during mode changes to maintain a stoichiometric air-fuel ratio, using a changing module to increase fuel injection in response to air amount increases and retarding ignition timing to reduce torque spikes, ensuring constant engine torque and minimizing NOx generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the air-fuel ratio of the mixture gas is made leaner than the stoichiometric air-fuel ratio to achieve high thermal efficiency and reduce NOx generation, then thermal efficiency is improved, but flame propagation stability deteriorates when engine water temperature or intake air temperature is low
Solution Approach 1:
The control system dynamically adjusts the air-fuel ratio based on operating conditions. When engine water temperature or intake air temperature is low, the system temporarily switches to a stoichiometric air-fuel ratio to ensure stable flame propagation, then transitions to a lean air-fuel ratio when temperatures are sufficient, achieving both reliability and efficiency through dynamic adaptation
Solution Approach 2:
The system changes the air-fuel ratio parameter from stoichiometric to lean based on temperature conditions. By monitoring engine water temperature and intake air temperature, the control system adjusts the air-fuel ratio parameter to maintain optimal combustion stability while maximizing thermal efficiency when conditions permit
2Use of energy by moving object
If the air amount is increased to achieve a lean air-fuel ratio for high thermal efficiency, then thermal efficiency is improved, but emission performance deteriorates during mode change due to temporary rich mixture conditions
Solution Approach 1:
The control system performs preliminary actions by increasing fuel injection amount before the air amount is fully increased during mode changes. This anticipatory fuel adjustment ensures the air-fuel ratio remains at or near stoichiometric during the transition, preventing temporary rich conditions that would degrade emission performance while still enabling the eventual switch to lean operation for improved thermal efficiency
Solution Approach 2:
The system uses feedback control by monitoring the air-fuel ratio during mode changes and adjusting fuel injection accordingly. When the air amount is increased to achieve lean operation, the system simultaneously adjusts fuel injection to maintain the air-fuel ratio within the stoichiometric window, ensuring emission performance is preserved while thermal efficiency is improved
3Object-generated harmful factors
If the fuel amount is increased to maintain stoichiometric air-fuel ratio during mode change, then emission performance is maintained, but engine torque increases causing torque shocks
Solution Approach 1:
The control system performs preliminary torque compensation by retarding ignition timing before and during the fuel injection increase. This anticipatory timing adjustment offsets the torque increase that would result from the fuel amount increase, maintaining emission performance while preventing torque shocks through proactive timing management
Solution Approach 2:
The system applies preliminary anti-action by retarding ignition timing to counteract the torque increase caused by increased fuel injection. This counterbalancing action prevents the harmful effect (torque shock) before it occurs, allowing the fuel amount to be increased for emission control without causing unacceptable torque 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
This approach prevents emission performance degradation and torque shocks during mode changes, maintaining engine efficiency and reducing NOx emissions by maintaining a stoichiometric air-fuel ratio and optimizing fuel delivery and ignition timing.
Implementation Method 1
combustion by compressed self-ignition in which a mixture gas combusts at once without flame propagation being intervened maximizes fuel efficiency
Implementation Method 2
a pressure buildup caused by the generation of heat and flame propagation of SI combustion
Implementation Method 3
a pressure buildup by a compression work of a piston during a compression stroke
Data Source
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AI summary
A control system for a compression ignition engine is provided, which includes a combustion chamber, a throttle valve, an injector, an ignition plug, a sensor, and a controller. A changing module outputs a signal to the throttle valve so that an air amount increases more than before the change demand, outputs to the injector a signal to increase the fuel amount according to the increase in the air amount so that an air-fuel ratio of the mixture gas becomes a stoichiometric air-fuel ratio or a substantially stoichiometric air-fuel ratio, and performs a torque adjustment so that an increase of the engine torque caused by the increase in the fuel amount is reduced. When the air amount is determined to have reached a given amount, the changing module ends the increasing of the fuel amount and the torque adjustment, and permits that a second mode module starts the second mode.