Turbocharger Speed Sensor Closed Loop Observer for Charge Air Mass Flow
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Solution Overview
Problem
Existing methods for determining the charge air mass flow rate in internal combustion engines with turbochargers, such as using mass air flow sensors, suffer from accuracy degradation due to contamination, especially in urban environments, leading to unreliable fuel injection and emission control.
Innovation Solution
A method that calculates a closed loop air mass flow rate by modeling the turbocharger revolution rate using a characteristic field stored in the engine controller, combining measured compressor pressure ratio and turbocharger speed, and adjusting with an offset value to improve measurement accuracy without relying on mass air flow sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass air flow sensors such as hot wire sensors are used to monitor air mass flow rate, then air mass flow rate can be measured, but measurement accuracy decreases over operational time due to deposits from contaminants
Solution Approach 1:
The patent extracts the air mass flow rate measurement function from the physical sensor and implements it through a computational model that calculates mass flow rate based on turbocharger revolution rate and compressor pressure ratio. This removes the dependency on physical sensors that are susceptible to contamination and degradation.
Solution Approach 2:
The patent replaces the mechanical/physical hot wire sensor with an electronic computational model. Instead of using a physical sensor that directly measures air mass flow, the system uses a controller to calculate mass flow rate from other measurable parameters (turbocharger speed and pressure ratio), substituting mechanical measurement with electronic computation.
2Reliability
If open loop air mass flow rate is determined from characteristic field using measured compressor pressure ratio and turbocharger revolution rate, then measurement can be obtained without sensor, but initial accuracy is limited compared to closed loop correction
Solution Approach 1:
The patent implements a feedback mechanism where the calculated air mass flow rate is used to update the modeled turbocharger revolution rate, which then feeds back into the mass flow rate calculation. This closed-loop feedback process continuously refines the measurement accuracy by correcting errors in the open-loop initial value.
Data Source
AI summary
A method for determining charge air mass flow rate comprises a turbocharger speed sensor with a closed loop observer that is based on a modeled turbocharger revolution rate. An open loop charge air mass flow rate is determined in a characteristic field stored in an engine controller and is corrected by the scaled difference between the measured and modeled turbocharger revolution rates. The corrected closed loop charge air mass flow is fed back to model the subsequent turbocharger revolution rate and to update the open loop charge air mass flow rate in the characteristic field.