Exhaust Gas Probe Lambda Correction for Catalytic Diagnosis
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Solution Overview
Problem
Internal combustion engines face challenges in maintaining low pollutant emissions due to changes in the response behavior of exhaust gas probes, leading to inefficient pollutant conversion and potential exceedance of maximum emissions limits, especially during catalytic converter diagnosis.
Innovation Solution
A device with a lambda controller and trim controller that uses a first exhaust gas probe upstream and a second probe downstream of the catalytic converter, along with a control signal unit to adjust fuel apportionment based on lambda correction and proportionate corrective factors, and a low-pass filter to decouple diagnosis from trim control, ensuring precise fuel adjustment and reduced emissions during diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a binary lambda probe is used upstream of the catalytic converter for lambda control, then the air-to-fuel ratio can be controlled to maintain stoichiometric conditions, but the response behavior of the probe changes as the air-to-fuel ratio varies, leading to inaccurate pollutant conversion control
Solution Approach 1:
The patent implements a feedback mechanism by using the second exhaust gas probe downstream of the catalytic converter to monitor the actual air-to-fuel ratio after conversion. This feedback signal is fed back to the control unit, which adjusts the lambda control accordingly to compensate for changes in the probe's response behavior, thereby maintaining accurate pollutant conversion control throughout the operating range.
Solution Approach 2:
The patent introduces a trim controller as an intermediary between the lambda controller and the fuel injection system. The trim controller receives the measurement signals from both probes and adjusts the fuel apportionment to compensate for probe response changes, acting as a mediator that maintains stable pollutant conversion despite varying operating conditions.
2Object-generated harmful factors
If exhaust gas probes are used to monitor air-to-fuel ratio changes, then pollutant emissions can be controlled, but the probes exhibit asymmetric response changes when transitioning between rich and lean values, reducing control precision
Solution Approach 1:
The patent uses the downstream exhaust gas probe to provide feedback on the actual air-to-fuel ratio after catalytic conversion. This feedback loop allows the control system to detect and compensate for asymmetric probe response changes, maintaining precise control over pollutant emissions regardless of whether the mixture is rich or lean.
Solution Approach 2:
The patent dynamically adjusts control parameters based on the operating mode (rich or lean) and the measured air-to-fuel ratio. The control unit modifies the lambda control and fuel injection parameters in response to probe signal changes, adapting the control strategy to compensate for asymmetric probe behavior at different operating points.
3Reliability
If diagnosis of the catalytic converter is performed using lambda control, then component performance can be evaluated, but the diagnosis process affects normal operation and may exceed emission limits
Solution Approach 1:
The patent segments the control functions into separate diagnostic mode and normal operation mode. During diagnosis, the system uses specific diagnostic parameters and control strategies that are distinct from normal lambda control. This segmentation allows accurate catalytic converter diagnosis while minimizing the impact on emission levels, as the diagnostic procedure can be isolated from continuous emission control.
Solution Approach 2:
The patent performs preliminary actions by establishing baseline emission levels and diagnostic parameters before actual diagnosis begins. The control unit pre-configures diagnostic sequences and emission compensation strategies, allowing diagnosis to be conducted in a controlled manner that prevents excessive emission spikes while maintaining diagnostic accuracy.
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 solution allows for precise diagnosis and significant reduction in pollutant emissions during catalytic converter diagnosis, ensuring compliance with emission regulations and maintaining low pollutant levels.
Implementation Method 1
exhaust gas catalytic converters, which convert the pollutant emissions which are generated during the combustion process of the air-to-fuel mixture in the relevant cylinders, into harmless substances
Implementation Method 2
on emptying, the oxidation is supported
Implementation Method 3
On storing the oxygen, especially the nitrogen oxides are reduced
Implementation Method 4
a first exhaust gas probe (42) upstream of the exhaust gas catalytic converter (21) and a second exhaust gas probe (43) downstream of the exhaust gas catalytic converter (21)
Implementation Method 5
the combustion of the air-to-fuel mixture in the cylinders
Data Source
AI summary
Disclosed is an internal combustion engine comprising at least one cylinder and an exhaust manifold in which a catalytic converter, a first exhaust gas probe, and a second exhaust gas probe are disposed. The first exhaust probe is located upstream from the catalytic converter while the second exhaust gas probe is arranged downstream therefrom. A lambda Controller is provided which is configured so as to determine a lambda correction factor in accordance with a first test signal that is assigned to the first exhaust gas probe. A trim controller is provided to which a setpoint value and an actual value of a second test signal allocated to the second exhaust gas probe are fed as a control difference. The trim controller is configured so as to determine a proportionate corrective factor. A control signal unit is embodied so as to determine a control signal for apportioning fuel into the cylinder in accordance with the lambda correction factor and additionally determine the control signal for apportioning fuel into the cylinder according to the proportionate corrective factor in a diagnostic mode of a component associated with the exhaust manifold.