Burner Control Using Existing Lambda Sensors
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Solution Overview
Problem
Existing methods for controlling burners in exhaust systems of internal combustion engines are economically disadvantageous due to the need for additional lambda sensors, which increase costs without providing optimal thermal power and air/fuel ratio control.
Innovation Solution
A method using an electronic control unit to control the burner by introducing exhaust gases upstream of existing lambda sensors, allowing the control system to manage air and fuel flow based on sensor data from these sensors, thereby eliminating the need for additional sensors and optimizing thermal power and air/fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a further lambda sensor is added to detect the air/fuel ratio of exhaust gases exiting the burner, then the control precision of the burner is improved, but the device complexity and cost increase
Solution Approach 1:
The existing lambda sensors in the exhaust system are made to serve dual functions: detecting exhaust gases from the engine and detecting exhaust gases from the burner. By strategically positioning the burner between the first and second lambda sensors, the system reuses existing sensors for burner control, eliminating the need for additional sensors while maintaining measurement capability
Solution Approach 2:
The existing lambda sensors and control unit are made to serve the additional function of burner control. The control unit, already present for engine management, is extended to also control the burner based on lambda sensor readings, making the system self-sufficient without requiring additional dedicated components
2Ease of manufacture
If the burner is positioned to introduce exhaust gases between the first and second lambda sensors, then the control cost is reduced by eliminating additional sensors, but the measurement accuracy for burner exhaust gases may be affected
Solution Approach 1:
The burner operates in periodic cycles, injecting fuel and generating exhaust gases at specific intervals. The control system is configured to read lambda sensor data and adjust burner operation in periodic cycles, allowing the system to maintain measurement accuracy while using existing sensors for dual purposes
Solution Approach 2:
The control unit continuously monitors lambda sensor readings and adjusts the burner operation in real-time based on feedback from the sensors. This closed-loop control ensures that the burner maintains the desired air/fuel ratio despite using shared sensors, compensating for any measurement interference
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 reduces costs by eliminating the need for extra sensors while effectively controlling the burner to achieve optimal thermal power and air/fuel ratio, enhancing the efficiency of the exhaust system.
Implementation Method 1
A combustion chamber is defined inside the burner, the chamber receives fresh air and receives fuel from an injector, which is designed to cyclically inject fuel inside the combustion chamber. In addition, a spark plug is coupled to the burner to determine the ignition of the mixture present inside the combustion chamber.
Data Source
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AI summary
A method to control an internal combustion engine (1) provided with an exhaust system (2) for the exhaust gases of a vehicle having an exhaust duct (10) and an exhaust gas after-treatment system (14) comprising at least one catalytic converter (15, 17) arranged along the exhaust duct (10); a burner (21) suited to introduce the exhaust gases into the exhaust duct (10) to speed up the heating of said at least one catalytic converter (15, 17), wherein a combustion chamber (22) is defined inside the burner (21) which receives fuel from an injector (27), designed to inject the fuel inside the combustion chamber (22) and the fresh air by means of an air feeding circuit (23) provided with a pumping device (24) that feeds the air, a shut-off valve (26) arranged upstream of the burner (21) and a mass air flow sensor (9; 39) interposed between the pumping device (24) and the shut-off valve (26); the method provides the following steps: calculating the thermal power (POBJ) required to reach the nominal operating temperature of said at least one catalytic converter (15, 17); determining the objective air flow rate (ṁA_OBJ) to be fed to the burner (21) to obtain said thermal power (POBJ) required to reach the nominal operating temperature of said at least one catalytic converter (15, 17); determining the nominal number (NNOM) of revolutions with which to operate the pumping device (24) by means of a map depending on the objective air flow rate (ṁA_OBJ), on the ambient pressure (PATM), on the ambient temperature (TATM) and on the pressure (PA) of the air entering the burner (21); determining a closed-loop contribution (NCL) of the number of revolutions with which to operate the pumping device (24) by means of a PID controller which tries to zero a difference between the objective air flow rate (ṁA_OBJ) and the air flow rate (ṁA) detected by the mass air flow sensor (9; 39); determining a further contribution (NADAT) of the number of revolutions with which to operate the pumping device (24) depending on the integral action of the PID controller under stationary conditions; and determining the actual number (N) of revolutions with which to operate the pumping device (24) by the sum of the nominal number (NNOM) of revolutions, the closed-loop contribution (NCL) of the number of revolutions with which to operate the pumping device (24) and the further contribution (NADAT) of the number of revolutions with which to operate the pumping device (24).