Pre-turbine WRO2 Sensor Signal Filtering for Engine Scavenging
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Solution Overview
Problem
Conventional turbocharged engine control systems face challenges in accurately measuring the fuel/air ratio during scavenging due to excessive variations in the exhaust gas mixture, requiring multiple oxygen sensors which are costly and inefficient.
Innovation Solution
A control system utilizing a single pre-turbine wide-range oxygen (WRO2) sensor that generates an unfiltered signal, which is then engine cycle average filtered to reduce variations, allowing for individual cylinder fuel control and emissions control during scavenging without the need for a post-turbine sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pre-turbine WRO2 sensor is used for individual cylinder fuel control, then cylinder-specific fuel optimization is achieved, but the sensor signal contains excessive variations due to insufficient exhaust gas mixing that degrade emissions control accuracy
Solution Approach 1:
The patent segments the WRO2 signal into two distinct components: an unfiltered signal used for individual cylinder fuel control and a filtered signal used for emissions control. This segmentation allows each control function to receive the appropriately processed signal, resolving the contradiction between measurement precision and emissions control accuracy.
Solution Approach 2:
The patent introduces an intermediary processing stage (signal filtering) between the WRO2 sensor and the emissions control system. This intermediary filter removes excessive variations from the signal, enabling accurate emissions control while preserving the cylinder-specific information in the unfiltered signal for fuel control.
2Reliability
If multiple oxygen sensors are installed (pre-turbine and post-turbine) to address both fuel control and emissions control requirements, then both control functions can operate accurately, but system cost and complexity increase
Solution Approach 1:
The patent makes the single pre-turbine WRO2 sensor multi-functional by processing its signal in two different ways: the unfiltered signal serves individual cylinder fuel control while the filtered signal serves emissions control. This eliminates the need for a separate post-turbine sensor, reducing system complexity while maintaining both control functions.
Solution Approach 2:
The patent merges the functions of multiple sensors into a single sensor by implementing different signal processing paths. Instead of installing separate pre-turbine and post-turbine sensors, the system combines both fuel control and emissions control functions into one sensor location, reducing component count and system complexity.
3Reliability
If the WRO2 signal is filtered to reduce variations for emissions control, then emissions accuracy is improved, but the filtered signal loses cylinder-specific variations needed for individual cylinder fuel control
Solution Approach 1:
The patent segments the signal processing paths so that the unfiltered WRO2 signal is preserved for individual cylinder fuel control while a separate filtered signal is generated for emissions control. This segmentation prevents information loss by ensuring cylinder-specific variations remain available where needed.
Solution Approach 2:
The patent performs preliminary signal filtering to create a smoothed version of the WRO2 signal before using it for emissions control. This preliminary action removes variations that would interfere with emissions accuracy while the original unfiltered signal remains available for fuel control purposes.
Data Source
AI summary
A system and method of utilizing a pre-turbine wide-range oxygen (WRO2) sensor during both individual cylinder fuel control (ICFC) and scavenging of a turbocharged engine involve receiving, by a controller and from the WRO2 sensor arranged in an exhaust system of the engine at a point upstream of a turbine of a turbocharger of the engine, an unfiltered WRO2 signal indicative of a fuel/air (FA) ratio of exhaust gas produced by the engine, performing, by the controller, ICFC by controlling the engine using the unfiltered WRO2 signal, performing, by the controller, engine cycle average filtering of the WRO2 signal to obtain a filtered WRO2 signal, and, while the engine is scavenging, performing, by the controller, engine FA ratio and emissions control using the filtered WRO2 signal.