Mass Airflow Sensor Signal Processing for Emission Compliance
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Solution Overview
Problem
Aftermarket performance intake systems face challenges in meeting stringent emission standards due to differences in airflow profiles, making it difficult to accurately measure mass airflow and maintain compliance with EPA requirements.
Innovation Solution
A system comprising a mass airflow sensor, microcontroller, analog-to-digital converter, and digital-to-analog converter, which processes signals to replicate the OEM mass airflow transfer function, allowing for accurate mass airflow measurement and compliance with emission standards by using lookup tables to convert performance and stock mass airflow transfer functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If aftermarket intake systems use larger diameter tubing and higher flowing air filters to improve engine performance, then engine power and efficiency are increased, but the mass airflow sensor output becomes inaccurate due to different airflow profiles
Solution Approach 1:
The patent applies parameter changes by implementing a dual transfer function approach. Instead of using a single fixed transfer function, the system dynamically selects between a first transfer function (for stock-style airflow) and a second transfer function (for performance-style airflow) based on detected airflow characteristics. This allows the mass airflow sensor to accurately measure both stock and performance intake systems without requiring different hardware, resolving the contradiction between improved engine performance and maintained measurement accuracy.
2Measurement precision
If the mass airflow sensor is calibrated for stock intake systems, then it provides accurate readings for OEM vehicles, but it produces inaccurate measurements when installed in performance intake systems
Solution Approach 1:
The patent implements universality by creating a mass airflow sensor system that can accurately serve multiple functions: it works with both stock intake systems and performance intake systems. The dual transfer function methodology allows the same sensor hardware to adapt to different airflow profiles by selecting the appropriate calibration curve, making the sensor universally compatible across different intake system types without requiring separate calibration for each application.
Solution Approach 2:
The system applies dynamics by making the transfer function selection dynamic rather than static. The ECU monitors airflow characteristics and automatically switches between the first and second transfer functions based on which profile better matches the current operating conditions. This dynamic adaptation allows the sensor to maintain accuracy whether the vehicle is using stock or performance intake components.
3Reliability
If oxygen sensor feedback and fuel trims are used to correct transfer function errors, then air/fuel ratio is maintained, but other critical functions like ignition timing and emission calculations remain inaccurate
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing multiple transfer functions that account for different intake system configurations. Rather than waiting for oxygen sensor feedback to correct errors, the system proactively selects the appropriate transfer function before emission-critical calculations are performed. This preliminary selection ensures that mass airflow measurements used for ignition timing, fuel injection, and emission control are already accurate, eliminating the need for post-hoc corrections.
Data Source
AI summary
A system, method and device for mass airflow sensor signal processing includes a microcontroller, a mass airflow sensor and an engine PCM. An analog-to-digital converter (ADC) converts a first output signal from the mass airflow sensor to a first VDC value. A digital-to-analog converter (DAC) converts a second VDC value to a second output signal associated with the mass airflow sensor. Transfer functions are obtained from a flow bench using the mass airflow sensor, performance air intake components, and stock air intake components. The microcontroller determines, from the first VDC value, a corresponding actual flow rate. From the actual flow rate, a corresponding stock VDC value is determined. The stock VDC value is then output to the DAC for conversion to the output second signal associated with the mass airflow sensor for communication to the engine PCM.