Common Rail Injector Opening Degree Measurement
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Solution Overview
Problem
Existing methods for determining the opening degree of injectors in combustion engines are unable to provide precise measurements, leading to potential increased emissions due to noise interference in the fuel pressure system, which can result in either under or over fuel injection.
Innovation Solution
A method involving simultaneous test injections across multiple cylinders to achieve a significant pressure fall beyond noise levels, allowing for precise calculation of each injector's opening degree, enabling accurate adaptation of opening times to maintain low emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If test injection is carried out in a single cylinder to determine injector opening degree, then the measurement process is simple, but the pressure fall is too small and close to noise level resulting in insufficient measurement precision
Solution Approach 1:
The patent combines test injections across multiple cylinders (at least two cylinders) to be performed simultaneously. By merging the fuel injection events from multiple cylinders, the cumulative pressure fall in the common rail becomes sufficiently large to be measured accurately above the noise level, thereby resolving the measurement precision issue without requiring complex individual cylinder isolation mechanisms
2Measurement precision
If fuel supply is interrupted to perform test injection, then the pressure fall can be accurately measured, but the fuel accumulation in common rail cannot be maintained
Solution Approach 1:
The patent performs the test injection while the fuel supply to the common rail is maintained in a ready state. The measurement is conducted during a brief measurement interval where fuel supply is temporarily paused only for the duration of the test injection, rather than interrupting the overall fuel supply sequence. This preliminary preparation ensures that fuel accumulation is preserved while still allowing accurate pressure fall measurement during the test window
3Quantity of substance
If opening time is extended to compensate for reduced opening degree, then the fuel amount can be maintained, but the emissions control precision deteriorates
Solution Approach 1:
The patent establishes a feedback loop where the measured pressure fall from test injections is used to calculate the actual injector opening degree. This measured opening degree information is then fed back to the control unit, which adjusts the opening time parameters accordingly. This closed-loop feedback system enables precise emissions control by continuously adapting the opening time based on actual injector performance rather than using fixed compensation values
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 method ensures precise determination of injector opening degrees, allowing for optimal fuel injection control and minimal emissions by repeating test injections across various combinations of injectors and cylinders, even when the engine is turned off, thereby maintaining low emission levels.
Implementation Method 1
the pressure decrease of the fuel in the fuel accumulator, resulting from the test injection is determined
Data Source
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AI summary
In a method to determine the opening degree of injectors (7) in cylinders in a combustion engine (2) with at least three cylinders, wherein the injectors are connected to a fuel accumulator (8) in a common rail fuel injection system, the fuel supply to the fuel accumulator (8) is interrupted, and subsequently a test injection of fuel is carried out into at least two and at most all except one cylinder at a time, in different combinations, at such a time that the injection does not cause any combustion in the cylinders. The pressure decreases caused in connection with the different test injections are measured, and the pressure decrease which is attributable to at least one specific injector is calculated based thereupon, for use in the determination of the injector's opening degree.