Oxygen Sensor Calibration via Fuel Cut Averaging
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Solution Overview
Problem
The existing method for calibrating oxygen sensors in internal combustion engines faces challenges in accurately calculating correction coefficients due to output pulsation and noise during fuel cut operations, making it difficult to maintain consistent detection accuracy over time.
Innovation Solution
An oxygen sensor control apparatus that calculates a correction coefficient by averaging multiple output values during fuel cut operations, using a plural-time average to mitigate noise and pulsation, and determining stability based on air supply amounts to ensure accurate calibration of oxygen sensor outputs with exhaust gas concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single output value of the oxygen sensor is compared with the reference output value to calculate the correction coefficient during fuel cut period, then the calculation process is simple, but the accuracy of the correction coefficient is low due to output pulsation and noise
Solution Approach 1:
The patent combines multiple output values obtained during the fuel cut period into a single averaged value. This merging approach eliminates the impact of momentary pulsations and noise by distributing the measurement across multiple data points, thereby improving correction coefficient accuracy without requiring complex additional hardware
Solution Approach 2:
The patent implements periodic fuel cut operations to collect multiple output values at regular intervals. By performing the fuel cut operation repeatedly and collecting output values during each period, the system accumulates sufficient data for accurate averaging while maintaining a structured and manageable calculation process
2Measurement precision
If multiple output values are averaged to calculate the correction coefficient, then the accuracy improves, but the calculation time and processing complexity increase
Solution Approach 1:
The patent applies partial averaging by selecting a predetermined number of output values (e.g., 10-20 values) rather than averaging all possible measurements. This partial action approach provides sufficient accuracy improvement while limiting the calculation time and processing load to manageable levels
Solution Approach 2:
The patent performs the averaging calculation during the fuel cut period itself, before the engine resumes normal operation. This preliminary action ensures that the correction coefficient is ready in advance, avoiding additional time loss after the fuel cut period ends and minimizing the impact on overall system response time
Data Source
AI summary
In an oxygen sensor control apparatus, a CPU obtains a correction coefficient for calibrating the relation between output value of an oxygen sensor and oxygen concentration when a fuel cut operation is performed. When the amount of scavenging air (total supply amount of air) becomes equal to or greater than a predetermined amount in each fuel cut period, the CPU calculates an average output value Ipav from a plurality of output values (concentration corresponding values) Ipr of the oxygen sensor, from which values deviating from a predetermined range R1 have been removed. Subsequently, the CPU averages the values obtained in a plurality of fuel cut periods to thereby obtain a plural-time average output value Ipavf. The CPU obtains a correction coefficient for correcting the actual output value Ip of the oxygen sensor 20 on the basis of the Ipavf value and a previously set reference output value.