EGR Valve Control for CNG Engine Exhaust Temperature
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Solution Overview
Problem
CNG engines face increased costs and complexity in maintaining exhaust gas temperature due to the need for additional sensors and complex configurations in EGR systems, which are not effectively addressed by existing control methods.
Innovation Solution
An engine system with an EGR valve control unit that measures exhaust gas temperature and adjusts the EGR valve opening degree based on engine operating conditions, increasing the opening when the temperature exceeds a reference value and decreasing it when it returns to or drops below that value, without requiring additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a UEGO sensor is added to the intake line for closed-loop EGR valve control, then exhaust gas temperature can be maintained at a reference value or lower, but manufacturing cost increases due to the expensive sensor
Solution Approach 1:
The patent extracts the temperature measurement function from the UEGO sensor location and relocates it to the exhaust line where exhaust gas temperature can be directly measured. This eliminates the need for the expensive UEGO sensor while maintaining the ability to control exhaust gas temperature through EGR valve regulation
Solution Approach 2:
The patent replaces the expensive UEGO sensor with a more economical temperature sensor positioned in the exhaust line. This substitution maintains functional effectiveness for temperature monitoring while significantly reducing manufacturing cost
2Temperature
If a UEGO sensor is added for closed-loop EGR control, then exhaust gas temperature can be controlled, but device complexity increases
Solution Approach 1:
The patent removes the UEGO sensor from the intake line configuration and extracts the temperature measurement function to a dedicated temperature sensor in the exhaust line. This simplifies the overall system by eliminating the complex closed-loop control architecture while maintaining temperature control capability
Solution Approach 2:
The patent employs a self-service control approach where the EGR valve is regulated based on direct temperature feedback from the exhaust line. This eliminates the need for additional UEGO sensors and complex closed-loop control systems, reducing device complexity while maintaining effective temperature control
3Temperature
If the EGR valve opening degree is increased to maintain exhaust gas temperature at reference value or lower, then exhaust gas temperature control is achieved, but the amount of exhaust gas recirculated increases
Solution Approach 1:
The patent implements dynamic adjustment of the EGR valve opening degree based on real-time exhaust gas temperature measurements. The valve opening is continuously optimized to maintain temperature at or below the reference value while minimizing unnecessary exhaust gas recirculation, adapting to varying operating conditions
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 allows for effective control of exhaust gas temperature without additional sensors, reducing manufacturing costs and simplifying the engine system while maintaining the temperature at or below a reference value.
Implementation Method 1
an exhaust gas recirculation (EGR) system decreases a combustion temperature of an engine by re-circulating part of exhaust gas, discharged from the engine, to a combustion chamber of the engine, thereby reducing the amount of nitrogen oxide NOx to be generated
Implementation Method 2
an exhaust gas temperature measuring device configured to measure a temperature of the exhaust gas discharged from the combustion chamber
Implementation Method 3
an exhaust gas recirculation (EGR) valve configured to regulate the amount of exhaust gas passing through the recirculation line
Data Source
AI summary
The present invention relates to control of an opening degree of an exhaust gas recirculation (EGR) valve which is provided in an engine which uses compressed natural gas as fuel. A method for controlling an EGR valve of an engine according to the present invention includes: calculating the amount of exhaust gas to be transferred from an exhaust line to an intake line according to engine operating conditions; regulating an opening degree of an EGR valve based on the calculated amount of exhaust gas; measuring a temperature of exhaust gas discharged from a combustion chamber; and increasing the opening degree of the EGR valve by a preset increment when the temperature of the exhaust gas discharged from the combustion chamber exceeds a preset reference temperature.