Diagnostic Device Variable Mask Period Fuel Injection
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Solution Overview
Problem
Conventional diagnostic techniques for fuel injection systems in engines face challenges in accurately determining failures due to temporary fluctuations in air-fuel ratios during mode changes, leading to erroneous failure determinations and delayed discovery of actual failures, which affects the stability and reliability of engine control, especially at higher engine speeds.
Innovation Solution
A diagnostic device with a processor and memory that calculates a corrected fuel injection amount and sets a variable mask period for suspending failure diagnosis upon mode changes, using the difference between target and measured air-fuel ratios, thereby preventing misdiagnosis and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a failure determination is prohibited without exception when the fuel injection mode is changed, then erroneous failure determination is prevented, but discovery of actual failures is delayed and diagnosis accuracy lowers
Solution Approach 1:
The mask period is made variable rather than fixed, allowing the diagnostic suspension period to be dynamically adjusted based on the corrected fuel injection amount. This enables the system to adapt the diagnosis prohibition duration to actual engine operating conditions, preventing unnecessary prolonged suspension while avoiding erroneous diagnoses during transient fluctuations.
Solution Approach 2:
The invention changes the parameter of mask period from a fixed time value to a variable value determined by the corrected fuel injection amount. By calculating the corrected value based on air-fuel ratio deviations and using it to set the mask period duration, the system optimizes the balance between preventing misdiagnosis and enabling timely failure detection.
2Reliability
If the mask period is extended to prevent misdiagnosis during mode changes, then erroneous failure determination is reduced, but actual failures occurring within the extended period cannot be detected
Solution Approach 1:
The mask period duration is dynamically adjusted based on the magnitude of corrected fuel injection amount. When the corrected value is small (indicating minor transient fluctuations), the mask period is shortened or eliminated, allowing immediate failure detection. When the corrected value is large (indicating significant mode transition effects), the mask period is extended to prevent misdiagnosis.
Solution Approach 2:
The system changes the mask period parameter from a conservative fixed value to an optimized variable value. By using the corrected fuel injection amount as the basis for setting the mask period, the system achieves the minimum necessary suspension duration to prevent erroneous diagnoses while maximizing the window for timely failure detection.
3Ease of operation
If a fixed mask period is used to simplify control logic, then implementation is easier, but it cannot adapt to different engine operation states and speeds
Solution Approach 1:
The invention introduces a calculated parameter (corrected fuel injection amount) that automatically reflects engine operation state. By using this parameter to determine the mask period, the system adapts to different engine speeds and operating conditions without requiring complex conditional logic or multiple fixed period settings.
Solution Approach 2:
The system uses its own calculated corrected fuel injection amount to automatically determine the appropriate mask period duration. This self-service approach eliminates the need for external input or complex control logic, as the system inherently adapts to operating conditions through its existing feedback control calculations.
Data Source
AI summary
A diagnostic device incorporates a processor and a memory and diagnoses a failure related to a fuel injection system for an engine whose air-fuel ratio of is feedback-controlled. The diagnostic device includes a calculation unit which calculates a corrected value of a fuel injection amount according to a difference between a target value and a measured value of the air-fuel ratio. The diagnostic device includes a setting unit which sets a mask period in which a failure diagnosis is suspended, according to the corrected value upon switchover of a fuel injection mode. The diagnostic device includes a diagnostic unit which does not carry out the diagnosis in the mask period and carries out the diagnosis outside the mask period.