Common-Rail Injection Controller Test Injection Pressure Drop
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Solution Overview
Problem
In common-rail injection systems, precise fuel dosage is challenging due to production-related component variances and aging phenomena, leading to deviations in injected fuel quantity, which existing methods struggle to accurately detect and compensate for.
Innovation Solution
A controller that performs test injections to determine the actual fuel quantity by evaluating pressure drops in the common fuel supply line, using a determination unit to form differences between reference and test measurement signals, allowing for higher flexibility and accuracy in adapting fuel injector actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel injections during normal operation are used to determine actually injected fuel quantity, then the system can maintain continuous operation, but the accuracy and flexibility of fuel quantity determination is limited
Solution Approach 1:
The system performs test injections before the actual fuel injection to establish a reference state. By conducting the test injection in advance and measuring the pressure drop, the system can determine the actual fuel quantity with higher accuracy without interfering with the main injection process. This preliminary measurement allows for more precise calibration of the fuel injection system.
2Measurement precision
If test injections are performed to determine actual fuel quantity, then measurement precision and adaptability improve, but the system complexity increases
Solution Approach 1:
The controller is designed to perform multiple functions: it controls the normal fuel injection process and also conducts test injections to measure pressure drops for determining actual fuel quantity. By making the controller multi-functional, the system avoids adding separate dedicated measurement devices, thus improving measurement precision while limiting the increase in overall system complexity.
3Measurement precision
If reference measurement signal is obtained without test injection and test measurement signal is obtained with test injection, then measurement precision considerably increases, but the time required for measurement increases
Solution Approach 1:
The system periodically intersperses test injections among the normal fuel injection cycles. The test injection is performed at a specific point in the engine cycle when the fuel injection system is in a stable state, allowing for accurate pressure drop measurement. By making the measurement process periodic rather than continuous, the system achieves high measurement precision while minimizing the time loss, as the test injection only occupies a brief window within the larger engine operation cycle.
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 more precise and accurate compensation for deviations in fuel injection, improving engine performance and reducing emissions by using test injections to enhance the accuracy of fuel quantity determination and adaptation.
Implementation Method 1
the pressure drop caused by the injections in the common fuel supply line of the common-rail injection system is evaluated and the fuel quantity actually injected during the injections is determined therefrom
Data Source
AI summary
A controller for a common-rail injection system includes a plurality of fuel injectors, a common fuel supply line for the fuel injectors, a high-pressure pump for supplying the common fuel supply line with fuel, and a pressure sensor for determining the pressure in the common fuel supply line. A determination unit evaluates data of the pressure sensor and, from the pressure drop caused by an injection in the common fuel supply line, determines the fuel quantity actually injected during this injection or a value derived therefrom. An adaption unit uses the results of the determination unit in order to adapt the actuation of the fuel injectors. The determination unit carries out at least one test injection, and the actually injected fuel quantity or a value derived therefrom is effected by way of the test injection or injections.