Virtual Mass Flow Sensor for Engine Air and EGR Measurement
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Solution Overview
Problem
Existing engine systems face challenges in accurately and reliably measuring fresh air mass flow and exhaust gas recirculation (EGR) mass flow due to high costs and reliability issues with physical sensors, especially on the exhaust side, where harsh conditions prevail.
Innovation Solution
A virtual mass flow sensor system calculates these flows using readily measurable intake side pressures, temperatures, and oxygen content, leveraging mathematical models and existing sensors to improve accuracy and reduce sensor costs, with a lambda sensor used to correct estimates and account for offset delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical flow sensors (hot-film sensors, Venturi tube sensors) are used to measure mass flows, then measurement accuracy is improved, but device cost and complexity increase significantly
Solution Approach 1:
The patent creates a virtual copy of the physical flow sensor by using mathematical models that replicate the measurement function. Instead of deploying expensive physical sensors in harsh exhaust environments, the system creates virtual sensors through software-based mass flow calculations using readily available sensor data from intake side pressure, temperature, and oxygen content measurements.
Solution Approach 2:
The patent replaces mechanical/physical sensing systems with a computational approach. Rather than using physical hot-film sensors or Venturi tube sensors that require complex hardware installation and calibration, the system substitutes these with mathematical models and algorithms that calculate mass flows from electrical sensor signals, eliminating the need for complex mechanical measurement devices.
2Measurement precision
If physical flow sensors are installed on the exhaust side to measure EGR mass flow, then measurement capability is improved, but reliability deteriorates due to harsh conditions (high temperature, pressure pulsations, combustion products)
Solution Approach 1:
The patent introduces intermediary measurements on the intake side (pressure, temperature, oxygen content) that indirectly provide information about exhaust side conditions. By measuring parameters in the less harsh intake environment and using mass conservation principles, the system obtains EGR mass flow data without placing sensors directly in the harsh exhaust environment where reliability would be compromised.
Solution Approach 2:
The system creates virtual sensors that replicate the measurement capability of physical exhaust side sensors without actually placing sensors in the harsh environment. The virtual mass flow sensors compute EGR mass flow and fresh air mass flow from intake side measurements, providing the same measurement capability while avoiding the reliability issues of physical sensors in high-temperature, high-pressure pulsation environments.
3Ease of manufacture
If inexpensive lambda sensors are used instead of expensive physical flow sensors, then device cost is reduced, but measurement speed and responsiveness worsen
Solution Approach 1:
The patent merges the data from multiple inexpensive sensors (intake side pressure sensor, temperature sensor, and lambda sensor) with mathematical models to create a comprehensive mass flow measurement system. By combining these lower-cost sensor inputs with computational processing, the system achieves measurement capability comparable to expensive fast-responding flow sensors while maintaining the cost benefits of using cheaper individual sensor components.
Solution Approach 2:
The system performs preliminary measurements on the intake side where conditions are more favorable and sensors can respond more quickly. By measuring pressure, temperature, and oxygen content upstream before the harsh exhaust environment, the system obtains data that can be processed into mass flow information faster than waiting for slow-responding lambda sensors to equilibrate in the exhaust stream, while still using inexpensive sensor hardware.
Data Source
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AI summary
A system and an approach for determining various flows in an internal combustion engine, such as an amount of recirculation exhaust gas flow through a controlled valve and a fresh air mass flow to an intake of an engine. Also, among the sensors accommodated in the system, is an inexpensive but slow-responding lambda sensor in the exhaust stream.