Intake Air Flow Rate Correction Using Coefficient of Variation
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Solution Overview
Problem
The fluctuation of intake air flow rate due to pulsation in the intake passage leads to significant fluctuations in the output signal of the air flow sensor, resulting in decreased calculation accuracy of the intake air flow rate and subsequently affecting the control accuracy of the air-fuel ratio.
Innovation Solution
A vehicle control apparatus that includes an air flow sensor and a control system. The control system reads the output signal from the air flow sensor, calculates the coefficient of variation of the data, subjects it to a smoothing process, and corrects the data based on the coefficient of variation to enhance the accuracy of the intake air flow rate calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a heat wire air flow sensor or Karman vortex air flow sensor is used to detect intake air flow rate, then the air flow rate can be measured, but the output signal fluctuates greatly due to pulsation in the intake passage
Solution Approach 1:
The control system performs preliminary actions by calculating the coefficient of variation from historical flow rate data before using it to correct current measurements. This preliminary statistical analysis prepares correction factors that compensate for pulsation effects in advance, allowing the system to maintain measurement accuracy despite signal fluctuations.
Solution Approach 2:
The system implements feedback by continuously monitoring the output signal from the air flow sensor, calculating the coefficient of variation from the data, and using this information to correct subsequent flow rate measurements. This closed-loop approach adjusts the measurement based on observed fluctuations, restoring accuracy to the intake air flow rate calculation.
2Speed
If the output signal from the air flow sensor is used directly for control, then the response is fast, but the calculation accuracy of intake air flow rate decreases
Solution Approach 1:
The control system performs preliminary calculations of the coefficient of variation using historical flow rate data before applying corrections to current measurements. This preliminary statistical processing enables the system to maintain fast response while improving accuracy through pre-computed correction factors that account for pulsation effects.
Solution Approach 2:
The system changes the parameter of flow rate data by applying correction factors derived from the coefficient of variation. Instead of using raw sensor output directly, the system transforms the data by adjusting it based on the calculated statistical parameters, thereby improving calculation accuracy while preserving response speed.
3Measurement precision
If smoothing process is applied to the flow rate data, then the calculation accuracy improves, but the response time increases
Solution Approach 1:
The system changes the approach by using the coefficient of variation as a correction parameter rather than applying traditional time-based smoothing. This parameter transformation allows the system to correct accuracy issues through statistical adjustment rather than temporal averaging, thereby improving measurement precision without the time delay associated with conventional smoothing methods.
Solution Approach 2:
The feedback mechanism uses the coefficient of variation calculated from historical data to correct current measurements instantly, rather than relying on time-delayed smoothing processes. This feedback-based correction approach maintains measurement accuracy while preserving real-time response capability, avoiding the time loss inherent in traditional smoothing techniques.
Data Source
AI summary
A vehicle control apparatus includes an air flow sensor provided in an intake passage of an engine. The vehicle control apparatus includes a control system configured to read an output signal from the air flow sensor as first flow rate data. The control system is configured to calculate a coefficient of variation of the first flow rate data, and subject the first flow rate data to a smoothing process to calculate second flow rate data. The control system is configured to correct the second flow rate data based on the coefficient of variation, to calculate corrected flow rate data indicating the intake air flow rate in the intake passage.