Synchronized Mixture Ratio Control Using Master-Slave Lambda Sensors
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Solution Overview
Problem
Multi-cylinder internal combustion engines with multiple lambda sensors upstream of a catalytic converter face challenges in achieving synchronized oscillations in mixture ratio controls due to independent control of cylinder groups, leading to mismatched oscillations in exhaust gas mixture ratio, affecting catalytic converter efficiency.
Innovation Solution
A control method where one lambda sensor acts as the 'master' and the others as 'slaves, with the electronic control unit using the master sensor's feedback to calculate and apply correction fuel amounts to slave sensor groups, ensuring phase synchronization of mixture ratio oscillations across all cylinders, utilizing a single PID controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple lambda sensors are used with independent PID controllers for each cylinder group, then the mixture ratio control is more precise for each group, but the oscillations in mixture ratio become unsynchronized and the overall control precision deteriorates
Solution Approach 1:
The patent merges multiple independent PID controllers into a single centralized PID controller that receives feedback from all lambda sensors and coordinates fuel injection across all cylinder groups. This unification ensures that oscillations in mixture ratio are synchronized across all cylinders while maintaining precise control, resolving the contradiction between group-specific precision and overall synchronization precision.
2Device complexity
If a single PID controller is used for all cylinders with one lambda sensor, then the device complexity is reduced, but the mixture ratio control precision for individual cylinder groups deteriorates
Solution Approach 1:
The patent makes a single PID controller universal by enabling it to receive feedback from multiple lambda sensors and control fuel injection for multiple cylinder groups simultaneously. This multi-functional approach maintains low device complexity while achieving high mixture ratio control precision for each individual cylinder group, as the single controller adapts to manage multiple groups based on their respective lambda sensor feedback.
3Adaptability or versatility
If multiple independent mixture ratio controls are used for different cylinder groups, then the adaptability to individual group conditions is improved, but the overall catalytic converter efficiency deteriorates due to unsynchronized oscillations
Solution Approach 1:
The patent implements a coordinated feedback mechanism where a single PID controller receives lambda sensor feedback from all cylinder groups and adjusts fuel injection for each group in a synchronized manner. This ensures that each cylinder group adapts to its specific conditions through dedicated lambda sensor feedback while the oscillations remain synchronized across all groups, thereby maintaining high catalytic converter efficiency.
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 method ensures precise and synchronized oscillations in the mixture ratio of exhaust gas fed to the catalytic converter, enhancing catalytic converter efficiency without requiring additional components or multiple PID controllers, thus providing an economic and straightforward solution.
Implementation Method 1
Measurements of the oxygen content of the exhaust gas, which is provided by a lambda sensor positioned upstream of the catalytic converter, are used to control the mixture ratio.
Implementation Method 2
a single PID controller, which regulates the amount of fuel injected, is used to track an intended value for the mixture ratio
Implementation Method 3
a catalytic converter 5... necessary for the correct functioning of the catalytic converters in the exhaust system
Data Source
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AI summary
Control method for the mixture ratio in a multi-cylinder internal combustion engine (1), the control method providing for the following: reading a first real value of the mixture ratio via a master lambda sensor (7a) associated with a first cylinder group (9a), reading a second real value of the mixture ratio via a slave lambda sensor (7b) associated with a second cylinder group (9b), calculating a first amount of fuel to inject into the cylinders (2) of the first cylinder group (9a) to track a mixture ratio target value by using the first real value of the mixture ratio as a feedback variable, calculating the mean of the second real value of the mixture ratio in the detection window, calculating a correction value for the amount of fuel to inject based on the difference between a target value and the mean of the second real value of the mixture ratio, and calculating a second amount of fuel to inject into the cylinders (2) of the second cylinder group (9b) by applying the correction value to the first amount of fuel to inject into the cylinders (2) of the first cylinder group (9a).