Fail-Safe Controller for Direct Injection Engine Fuel Pressure
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Solution Overview
Problem
Conventional high-pressure fuel supply systems for direct injection engines lack the ability to distinguish between malfunctions in fuel pressure sensors and high-pressure pumps, leading to inadequate fail-safe controls that do not account for the specific faulty component or the timing of the malfunction.
Innovation Solution
A fail-safe controller that compares fuel pressure with first and second thresholds to differentiate between malfunctions in fuel pressure sensors and high-pressure pumps, executing appropriate fail-safe controls to maintain engine operation or shut it down accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined fail-safe control is executed without distinguishing the faulty portion, then the control logic is simple, but the reliability of the fail-safe control is insufficient
Solution Approach 1:
The malfunction detection is segmented into multiple independent detection processes: fuel pressure sensor malfunction detection and high-pressure pump malfunction detection. Each detection process uses specific threshold comparisons (first threshold for sensor, second threshold for pump) to identify the faulty component, enabling differentiated fail-safe controls for each scenario without requiring complex unified logic.
2Duration of action of moving object
If the same fail-safe control is executed for all malfunctions, then the control strategy is simple, but the duration of engine operation is reduced
Solution Approach 1:
Different fail-safe controls are applied to different malfunction scenarios based on local characteristics: when the fuel pressure sensor malfunctions, the engine continues operating with feed pump pressure; when the high-pressure pump malfunctions, the engine shuts down immediately. This localized differentiation maximizes operational duration for each specific failure mode while maintaining overall control simplicity.
3Measurement precision
If no differentiation is made between sensor and pump malfunctions, then the detection system is simple, but the precision of malfunction identification is insufficient
Solution Approach 1:
The detection system uses different threshold parameters to identify different malfunction types: the first threshold (lower) detects fuel pressure sensor failures, while the second threshold (higher) detects high-pressure pump failures. This parameter differentiation enables precise malfunction identification using a simple single-sensor system, avoiding the need for complex multi-sensor detection arrangements.
Data Source
AI summary
A fuel pressure varies according to whether a fuel pressure sensor and a high-pressure pump have a malfunction or not. In view of this, a first threshold Perr1 is defined for determining whether the fuel pressure sensor has a malfunction and a second threshold Perr2 is defined for determining whether the high-pressure pump has a malfunction. The second threshold Perr2 is greater than the first threshold Perr1. By comparing a detection value of the fuel pressure sensor with the first and the second threshold, a malfunction in the fuel pressure sensor and a malfunction in the high-pressure pump are distinguished from each other. A first fail-safe control or a second fail-safe control is executed according to a portion having a malfunction.