Pressure-Regulating Valve Diagnosis in Fuel Injection Systems

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Solution Overview

Problem

Conventional methods for diagnosing the operating state and maintenance of pressure-regulating valves in fuel injection systems of internal combustion engines face inaccuracies due to unwanted pressure drops caused by leaks in the high-pressure connection of the feed device during the overrun mode, which cannot be clearly distinguished from pressure drops due to the pressure-regulating valve.

Innovation Solution

Setting a non-zero delivery quantity of fuel to the pressure reservoir during the overrun mode prevents dynamic pressure effects and leaks, allowing for accurate determination of the fuel pressure and operating state of the pressure-regulating valve by ensuring that pressure changes are attributed primarily to the valve's operation rather than leaks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If no fuel is delivered to the pressure reservoir during overrun mode (conventional method), then fuel consumption is reduced, but pressure drops occur due to leaks in the high-pressure connection that cannot be distinguished from pressure-regulating valve effects

Engineering Contradiction:

Improvefuel consumptionVSAvoiddetermination accuracy of pressure-regulating valve operating state

Core Design Contradiction:

Loss of energyVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by delivering a predefined minimum quantity of fuel to the pressure reservoir before diagnosing the pressure-regulating valve during overrun mode. This preliminary fuel delivery compensates for potential leaks in the high-pressure connection, ensuring that pressure changes during diagnosis are solely due to the pressure-regulating valve operation, not confounding leak effects.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a non-zero delivery quantity is set during overrun mode, then pressure drops due to leaks are prevented, but this deviates from conventional overrun mode operation where no fuel delivery occurs

Engineering Contradiction:

Improvesystem leak-free operationVSAvoidoverrun mode operation flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the delivery quantity adaptive rather than fixed. During normal overrun mode, no fuel is delivered. However, when diagnosis of the pressure-regulating valve is required, the system dynamically switches to delivering a predefined minimum quantity of fuel. This dynamic adjustment maintains conventional operation during normal overrun while enabling reliable diagnosis when needed.

Inventive Principle:

Principle #15Dynamics

3Stress or pressure

If fuel injections occur during overrun mode, then fuel pressure can be maintained, but unnecessary effects on fuel pressure in the pressure reservoir occur that interfere with accurate diagnosis

Engineering Contradiction:

Improvefuel pressure maintenanceVSAvoidfuel pressure measurement accuracy for valve diagnosis

Core Design Contradiction:

Stress or pressureVSMeasurement precision

Solution Approach 1:

The patent applies the taking out principle by extracting and isolating the pressure-regulating valve diagnosis from the complex fuel injection process. During diagnosis, the system prevents fuel injections to injectors while maintaining a simplified fuel delivery through the feed device. This extraction of the diagnostic function from normal injection operations eliminates confounding pressure effects and enables accurate determination of pressure-regulating valve operating state.

Inventive Principle:

Principle #2Taking out (Extraction)

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 enables a highly accurate assessment of the pressure-regulating valve's state by maintaining a substantially leak-free system, excluding errors from dynamic pressure effects and allowing for precise derivation of operational information and maintenance status.

Implementation Method 1

a feed device for delivering fuel to the pressure reservoir... a high-pressure pump for delivering fuel to the common rail

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

a pressure-regulating valve for reducing the fuel pressure in the pressure reservoir to a lower fuel pressure

Methodology Applied

Scientific EffectPressure drop: Pressure Drop

Data Source

PatentUS9140205B2Method and device for operating a pressure-regulating valve

Publication Date: 2015.09.22 ROBERT BOSCH GMBH

AI summary

A method for operating a pressure-regulating valve of a fuel injection system of an internal combustion engine of, in particular, a motor vehicle; the fuel injection system including a pressure reservoir for storing pressurized fuel, as well as a feed device for delivering fuel to the pressure reservoir; and fuel being removable from the pressure reservoir via the pressure-regulating valve. In an overrun mode of the internal combustion engine, a delivery quantity of fuel delivered to the pressure reservoir by the feed device is set to a value greater than zero, and that a fuel pressure in the pressure reservoir is ascertained.