Engine Control Device Dynamic Threshold for Boost Diagnosis
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Solution Overview
Problem
Conventional engine devices face erroneous diagnoses in abnormality diagnosis of the relationship between intake air amount and supercharging pressure due to the use of a constant threshold, regardless of boost control status, leading to potential misinterpretations.
Innovation Solution
The engine device incorporates a control system that adjusts the threshold for abnormality diagnosis based on whether boost control is performed, setting a lower permissible upper limit during boost control and refraining from diagnosis until a predetermined time has elapsed to avoid erroneous readings, and considers engine rotational speed to accurately assess intake air amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant threshold is used for abnormality diagnosis regardless of boost control status, then the diagnosis system is simple to implement, but erroneous diagnoses occur due to incorrect threshold values during boost control
Solution Approach 1:
The threshold value is made dynamic by adjusting it based on the boost control status. When boost control is detected, the threshold is increased to account for the intentional deviation between intake air amount and supercharging pressure relationship. This resolves the contradiction by making the diagnosis system adaptive rather than static, preventing erroneous diagnoses during boost control while maintaining simplicity.
Solution Approach 2:
The threshold parameter is changed based on the operating condition (boost control status). The control device detects whether boost control is being performed and selects an appropriate threshold value accordingly. This parameter change allows the same diagnosis system to accurately diagnose abnormalities both during and outside boost control without increasing structural complexity.
2Measurement precision
If the permissible upper limit is reduced during boost control to avoid erroneous diagnosis, then diagnosis accuracy improves, but the system may miss actual abnormalities due to overly restrictive thresholds
Solution Approach 1:
The permissible upper limit is made dynamic based on boost control status. During boost control, the limit is increased to accommodate the intentional changes in the intake air amount-supercharging pressure relationship. Outside boost control, the normal limit applies. This dynamic adjustment ensures that actual abnormalities are not missed while preventing false positives during boost control.
Solution Approach 2:
The system uses feedback from the boost control status detection to adjust the permissible upper limit. By continuously monitoring whether boost control is active and adjusting the threshold accordingly, the system maintains high detection reliability without sacrificing diagnosis accuracy. The feedback mechanism ensures the threshold adapts to current operating conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces erroneous diagnoses by dynamically adjusting thresholds and timing, ensuring accurate abnormality diagnosis and preventing misinterpretations during boost control operations.
Implementation Method 1
a turbine 41 that is arranged in an exhaust pipe 35 of the engine 12, a compressor 42 that is arranged in an intake pipe 23 of the engine 12 and that is driven by the turbine 41
Data Source
AI summary
An engine device is equipped with an engine, a supercharger having a turbine, a compressor and a waste gate valve, and a control device that controls the engine and the supercharger, and that performs an abnormality diagnosis of a relationship between an intake air amount of the engine and a supercharging pressure as a pressure downstream of the compressor in the intake pipe. The control device performs boost control for controlling the waste gate valve such that the supercharging pressure becomes higher when a predetermined condition is fulfilled than when the predetermined condition is not fulfilled. The control device further sets a threshold for use in the abnormality diagnosis, based on whether or not the boost control is performed.