Oxygen Storage Measurement Using Discrete Lambda Sensor Correction
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Solution Overview
Problem
Existing methods for determining the oxygen storage capability of emission control systems, such as three-way catalytic converters, face inaccuracies due to the need for complex wideband lambda sensors and potential release of toxic gases, especially when using discrete-level sensors for open-loop control testing.
Innovation Solution
The procedure involves using a simple discrete-level exhaust gas sensor to measure control interventions and correct lambda values during the determination of oxygen storage capability, compensating for pre-control errors and ensuring accurate oxygen storage calculations by averaging control interventions during steady-state engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a wideband lambda sensor is used to measure lambda values in front of the emission control system, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses a discrete-level lambda sensor (simpler device) to measure lambda values and then applies correction factors to compensate for the quantization errors. This creates a functional copy of the wideband sensor's capability through computational correction rather than requiring the complex wideband sensor hardware itself.
Solution Approach 2:
The patent replaces the physical complexity of a wideband lambda sensor with a computational approach using a discrete-level sensor plus correction algorithms. The correction factors substitute for the continuous measurement capability, transforming a hardware problem into a software/mathematical solution.
2Ease of operation
If open-loop control is used during oxygen storage capability determination, then ease of operation is improved, but measurement precision deteriorates due to pre-control errors
Solution Approach 1:
The patent implements feedback by measuring the actual lambda values during open-loop control and using these measurements to calculate correction factors. These correction factors are then applied to compensate for the pre-control errors, creating a feedback loop that improves precision without requiring closed-loop control during the test.
Solution Approach 2:
The patent performs preliminary measurement of lambda values during the open-loop control phase to determine correction factors before the actual oxygen storage capability calculation. This preliminary action allows the system to account for and correct pre-control errors in advance.
3Productivity
If lambda value displacement is used to determine oxygen storage capability, then productivity is improved, but object-generated harmful factors increase due to toxic gas release
Solution Approach 1:
The patent replaces the harmful physical process of large lambda displacements with a computational method using correction factors. Instead of intentionally creating toxic conditions to test the system, the patent uses measured lambda values and mathematical corrections to determine oxygen storage capability, eliminating the need for harmful gas release.
Data Source
AI summary
The invention concerns a procedure to determine the oxygen storage capability of an emission control system with an exhaust gas sensor with discrete-level ability disposed in front of the emission control system.If in a period of time before the determination of the oxygen storage capability, the control intervention of the exhaust gas sensor is ascertained, and if this mean value is taken into consideration when calculating the fuel-delivery control phase during the determination of the oxygen storage capability of the emission control system, or if this mean value is used to correct the lambda value used to calculate the amount of oxygen stored, an improved measuring accuracy can be achieved while using a cost effective discrete level sensor. In that during the rich or lean operation of the cycle to determine the oxygen storage capability, the mean value of the control intervention is used for the calculation, pre-control errors are compensated for, as they can arise, for example, through dispersion of the injection valves or errors in the acquisition of cylinder fill. If the mean value is used to correct the lambda value, the amount of oxygen stored can be more accurately determined as a result of the measured air mass. In the procedure according to the invention, a cost effective step discrete-level sensor can be used in front of the emission control system.