Fuel Rail Relief Valve Detection Without Pump Feedback Control
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Solution Overview
Problem
Existing relief valve determination methods in high-pressure fuel supply systems are ineffective in determining the open status of a relief valve when the discharge amount of the high-pressure pump is not feedback-controlled, as they rely on feedback control to assess system abnormalities.
Innovation Solution
A relief valve determination device that estimates fuel pressure based on fuel injection amount and determines the open status of the relief valve by comparing the estimated pressure with the detected pressure, regardless of the feedback control status of the high-pressure pump, using an estimation unit and a determination unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If relief valve determination relies on feedback control of high-pressure pump discharge amount, then determination accuracy is improved, but system applicability deteriorates because it cannot be used when feedback control is not implemented
Solution Approach 1:
The patent introduces an estimation unit as an intermediary that calculates estimated fuel pressure based on fuel injection amount and system parameters. This intermediary estimation mechanism allows the determination device to function independently of feedback control, bridging the gap between measured and actual pressure while maintaining determination accuracy across different system configurations
Solution Approach 2:
The patent changes the determination approach from relying on feedback control parameters to using fundamental system parameters (fuel injection amount, rail volume, bulk modulus) that remain valid regardless of feedback control implementation. This parameter transformation enables universal applicability while preserving determination capability
2Reliability
If fuel pressure variations are not suppressed, then real pressure conditions are reflected, but determination reliability deteriorates due to pressure fluctuations affecting judgment accuracy
Solution Approach 1:
The patent applies beforehand cushioning by comparing estimated pressure (which smooths variations) with actual detected pressure. The estimation unit calculates pressure based on fundamental parameters that inherently filter out transient fluctuations, providing a stable reference that cushions the determination process against pressure variations while still reflecting genuine pressure conditions
Data Source
AI summary
An estimation unit estimates a fuel pressure on a discharge side of a high-pressure pump based on an amount of fuel injection with a fuel injection valve from a time point at which a detected fuel pressure changes from a higher status than a first pressure to a lower status, assuming that the fuel has not been discharged with the high-pressure pump. The determination unit determines that a relief valve is in an open status based on a dropping mode of the estimated fuel pressure and a dropping mode of the detected fuel pressure.