Fuel Pressure Sensor Diagnosis Using Feedback Control
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Solution Overview
Problem
Conventional fuel pressure sensor abnormality diagnosis apparatuses fail to diagnose fuel pressure sensor abnormalities when the fuel discharge amount reaches its maximum and the detected value is less than the target value, preventing formal diagnosis and potentially leading to incorrect assessments.
Innovation Solution
The apparatus includes a fuel pressure sensor abnormality diagnosis unit that, through feedback control, increases the fuel discharge amount when the detected value is less than the target value, and diagnoses sensor abnormalities even when the fuel discharge amount is at its maximum, by monitoring changes in the detected value over predetermined periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fuel discharge amount is increased to make the detected value coincide with the target value, then the fuel pressure control accuracy is improved, but when the fuel discharge amount reaches its maximum, the system loses the ability to perform further adjustment and cannot diagnose sensor abnormalities
Solution Approach 1:
The system performs preliminary abnormality diagnosis checks before the fuel discharge amount reaches its maximum limit. By monitoring the relationship between the detected value and target value during the feedback control process, the system can identify sensor abnormalities while adjustment capacity is still available, preventing the situation where diagnosis becomes impossible due to maximum discharge being reached.
2Speed
If the fuel discharge amount is feedback controlled to make the detected value coincide with the target value, then the fuel pressure control responsiveness is improved, but the diagnostic capability is lost when the discharge amount reaches maximum and can no longer be increased
Solution Approach 1:
The system utilizes the existing feedback control mechanism not only for pressure regulation but also for abnormality diagnosis. By continuously monitoring whether the detected value appropriately responds to changes in the target value during feedback control, the system can detect sensor abnormalities while maintaining responsive fuel pressure control, without requiring additional adjustment capacity beyond the maximum discharge limit.
3Measurement precision
If the system waits for the fuel discharge amount to reach maximum before diagnosing abnormalities, then the diagnosis accuracy is improved, but the response time is increased and the system cannot diagnose when maximum is already reached
Solution Approach 1:
The system performs abnormality diagnosis checks preliminarily during the feedback control process before the fuel discharge amount reaches its maximum. This allows the system to maintain high diagnosis accuracy by checking while adjustment capacity is available, while simultaneously reducing diagnosis time by not waiting for maximum discharge to be reached.
Data Source
AI summary
The fuel pressure sensor abnormality diagnosis apparatus diagnoses that a fuel pressure sensor is abnormal in the case where, because a state where a detected value of the fuel pressure sensor is less than a target value occurs, a fuel discharge amount of a fuel pump is increased, and as a result, the fuel discharge amount reaches its maximum amount, and even if a predetermined period has elapsed since the fuel discharge amount reaches its maximum amount, the detected value is less than the target value.