Compressed Self-Ignition Engine Control Device Torque Limit Adjustment
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Solution Overview
Problem
Existing control methods for compressed self-ignition engines fail to simultaneously ensure operability and reduce fuel consumption when switching between spark-ignition and compressed self-ignition combustion modes, particularly due to changes in air-fuel ratios caused by environmental and operational variations.
Innovation Solution
A control device for a compressed self-ignition engine that adjusts the upper limit of the compressed self-ignition combustion region based on the air-fuel ratio, using sensors to determine the optimal combustion mode and torque distribution between spark-ignition and compressed self-ignition types, thereby maintaining stable operation and reducing fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the air-fuel ratio is set to be lean in compressed self-ignition type combustion to reduce fuel consumption and NOx emissions, then fuel economy and emission performance are improved, but the engine torque is limited to lower loading and the engine rotational speed is limited to lower rotational speed
Solution Approach 1:
The patent applies dynamics by making the upper limit torque of the compressed self-ignition type combustion region variable rather than fixed. The control device dynamically adjusts the upper limit torque based on the actual air-fuel ratio conditions, allowing the engine to operate at higher torques when the air-fuel ratio is leaner than expected, and at lower torques when the air-fuel ratio is richer, thereby resolving the contradiction between fuel economy and engine torque output.
2Loss of energy
If the air-fuel ratio becomes excessively rich in compressed self-ignition type combustion, then the oxidation reaction of fuel becomes difficult due to decline of oxygen concentration and temperature, but combustion stability declines eventually leading to misfire
Solution Approach 1:
The patent applies feedback by using the air-fuel ratio sensor to detect the actual air-fuel ratio during compressed self-ignition type combustion and feeding this information back to the control device. The control device then adjusts the upper limit torque of the compressed self-ignition type combustion region based on this feedback, preventing misfire by reducing the upper limit torque when the air-fuel ratio becomes excessively rich, thus maintaining combustion stability while pursuing fuel economy.
3Loss of energy
If a large amount of exhaust gas is introduced into the cylinder to achieve compressed self-ignition type combustion, then fuel economy is improved, but the fresh air quantity is limited and the engine torque is limited to lower loading
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the upper limit torque of the compressed self-ignition type combustion region based on the actual air-fuel ratio. When the air-fuel ratio is leaner than expected (indicating sufficient fresh air), the system allows higher torque operation, thereby compensating for the limited fresh air quantity caused by exhaust gas introduction while maintaining fuel economy benefits.
4Power
If the upper limit of torque in the compressed self-ignition type combustion region is increased to meet driver torque demand, then engine torque is improved, but the air-fuel ratio becomes excessively rich leading to misfire
Solution Approach 1:
The patent applies dynamics by making the upper limit torque variable based on actual air-fuel ratio conditions. The control device continuously monitors the air-fuel ratio and adjusts the upper limit torque accordingly, allowing the engine to operate at higher torques when conditions permit (lean air-fuel ratio) and automatically reducing the upper limit torque when the air-fuel ratio becomes excessively rich, thus preventing misfire while maximizing torque output.
Solution Approach 2:
The patent applies feedback by using the air-fuel ratio sensor to detect the actual air-fuel ratio and feeding this information back to the control device, which then adjusts the upper limit torque of the compressed self-ignition type combustion region. This feedback mechanism ensures that torque increases do not lead to excessively rich air-fuel ratios and subsequent misfire, maintaining combustion stability.
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
The control device effectively suppresses misfires and ensures operability while utilizing the potential for fuel savings in compressed self-ignition combustion, even when air-fuel ratios change, by dynamically adjusting the combustion region and mode switching.
Implementation Method 1
a compressed self-ignition type internal combustion engine having: an injector for directly injecting fuel into a combustion chamber; an ignition device for igniting the fuel injected into the combustion chamber; an intake valve provided in an intake side of a cylinder that makes up a part of the combustion chamber, and of which actuating timing is controllable; an exhaust valve provided in an exhaust side of the cylinder, and of which actuating timing is controllable
Implementation Method 2
the progress of the oxidation reaction of fuel becomes difficult due to a decline of the concentration of oxygen and the temperature of the air-fuel mixture in the cylinder
Data Source
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AI summary
An object is to provide a control device and control method for a compressed self-ignition type internal combustion engine, which can reduce torque variation due to misfire when the air-fuel ratio varies during compressed self-ignition type combustion, and thereby effectively use the potential for reducing fuel consumption. As the combustion mode, a spark-ignition type combustion mode by use of an ignition plug and a compressed self-ignition type combustion mode which utilizes a pressure increase in a combustion chamber in association with upward movement of piston are selectively set depending on an operational state of the engine, and when the air-fuel ratio in the compressed self-ignition type combustion mode is rich, a regional upper limit of the compressed self-ignition type combustion region is changed toward the lower engine torque side, and when the air-fuel ratio is lean, the regional upper limit is changed toward the higher engine torque side.