Nozzle Vane Opening Degree Map Creation for Air-Fuel Ratio Sensor Accuracy
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Solution Overview
Problem
Existing methods for creating opening degree maps for nozzle vanes in internal combustion engines do not consider the exhaust gas blow on the air-fuel ratio sensor, leading to varying detection accuracy across cylinders.
Innovation Solution
A method that involves performing an imbalance operation under specific engine states to calculate air-fuel ratio fluctuation amounts, determining optimal nozzle vane opening degrees that meet specific conditions to minimize variation in exhaust gas blow on the air-fuel ratio sensor, and storing these as an opening degree map.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the opening degree map of nozzle vanes is created without considering exhaust gas blow on the air-fuel ratio sensor, then the map creation process is simple, but the detection accuracy of the air-fuel ratio sensor varies across cylinders
Solution Approach 1:
The patent performs preliminary imbalance operations and air-fuel ratio measurements during the map creation phase to pre-determine the optimal opening degree that ensures sufficient exhaust gas blow on the sensor. By conducting these measurements in advance during map creation rather than during normal operation, the system establishes accurate opening degree settings before actual engine use, ensuring consistent detection accuracy without adding complexity to the operational control system.
Solution Approach 2:
The patent uses feedback from air-fuel ratio sensor measurements during the map creation process to determine the optimal opening degree. The controller measures air-fuel ratios at different nozzle vane opening degrees and uses this feedback information to identify the opening degree that provides sufficient and consistent exhaust gas blow on the sensor across all cylinders, thereby ensuring accurate detection while systematically resolving the trade-off between accuracy and complexity.
2Reliability
If the opening degree of nozzle vanes is not optimized for exhaust gas blow, then the actuator load is reduced, but the air-fuel ratio detection accuracy varies
Solution Approach 1:
The patent determines the optimal nozzle vane opening degree in advance during the map creation phase by performing imbalance operations and measuring air-fuel ratios. This preliminary determination ensures that the opening degree is set to provide sufficient exhaust gas blow on the air-fuel ratio sensor for reliable detection, while the actuator only needs to position the vanes at this predetermined optimal degree during normal operation, balancing detection reliability with actuator energy consumption.
3Measurement precision
If imbalance operations are performed to determine optimal opening degree, then detection accuracy is improved, but the time required for map creation increases
Solution Approach 1:
The patent performs the time-consuming imbalance operations and air-fuel ratio measurements during the map creation phase rather than during normal engine operation. By conducting these measurements in advance when the engine is being tested and calibrated, the system captures the necessary data to determine optimal opening degrees without impacting real-time operational performance. The results are then stored in the opening degree map for use during normal operation, effectively transferring the time cost from operational loss to initial setup investment.
Data Source
AI summary
A map creating method for nozzle vanes includes performing an imbalance operation as many times as the number of the cylinders while changing the specific cylinder, creating air-fuel ratio data indicating changes in the air-fuel ratio during the imbalance operation, calculating an air-fuel ratio fluctuation amount for each of pieces of the air-fuel ratio data, determining whether a specific condition is met, the specific condition being that a minimum value among the air-fuel ratio fluctuation amounts is greater than or equal to a first determination value and a difference between the minimum value and a maximum value among the air-fuel ratio fluctuation amounts is less than or equal to a second determination value, and storing, as an opening degree map, the opening degree of the nozzle vanes meeting the specific condition in association with the engine operating state.