High-Pressure Bore Segmentation for Fuel Injector Pressure Peak Reduction
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Solution Overview
Problem
In large internal combustion engines with modular common rail systems, the first pressure peak occurring when the injection nozzle closes leads to significant pressure fluctuations and wear, which existing resonator systems are unable to effectively reduce.
Innovation Solution
The high-pressure bore is designed with a first section adjoining the high-pressure accumulator and a second section connecting to the injection nozzle, where the first section has a larger flow cross-section than the second, reducing the liquid column and corresponding pressure peak by optimizing the length and cross-sectional ratio of these sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a resonator line is provided to reduce pressure pulsations, then pressure oscillations are reduced, but the first pressure peak occurring immediately when the injection nozzle closes cannot be reduced
Solution Approach 1:
The high-pressure bore is segmented into two sections with different flow cross-sections: a first section with a larger flow cross-section and a second section with a smaller flow cross-section. This segmentation allows the liquid column to be reduced more effectively, thereby lowering the first pressure peak that occurs immediately when the injection nozzle closes.
Solution Approach 2:
Different sections of the high-pressure bore are given different flow cross-sectional properties. The first section has a larger flow cross-section to reduce the liquid column and first pressure peak, while the second section has a smaller flow cross-section. This local differentiation of properties enables the system to address multiple pressure-related issues simultaneously.
2Device complexity
If the high-pressure bore has a uniform cross-section, then the structure is simple, but the first pressure peak is significant causing wear and injection rate fluctuations
Solution Approach 1:
The high-pressure bore transitions from a uniform cross-section design to a non-uniform design with different sections having different flow cross-sections. The first section has a larger flow cross-section while the second section has a smaller flow cross-section, creating local quality variations that reduce the liquid column and first pressure peak without significantly increasing overall structural complexity.
Solution Approach 2:
The flow cross-section parameter of the high-pressure bore is changed along its length, transitioning from a constant value to a variable value. The first section has a larger flow cross-section parameter while the second section has a smaller flow cross-section parameter, which changes the hydraulic characteristics and reduces pressure peaks.
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 design effectively lowers the first pressure peak and minimizes pressure fluctuations, reducing wear and maintaining consistent injection rates across varying operating states.
Implementation Method 1
a resonator bore (20) connected parallel to the high-pressure bore (8) between the injection nozzle (2) and the high-pressure accumulator (6), which is connected to the high-pressure accumulator via a resonator throttle (21)
Implementation Method 2
When the injection nozzle closes, the fuel runs against a closed end of the line, with the pressure in front of the injection nozzle increasing significantly due to the inertia of the fuel
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a device for injecting fuel into the combustion chamber of an internal combustion engine, comprising at least one injector (1) that has: a high-pressure accumulator (6), which is integrated into the injector body, an injection nozzle (2) that has a nozzle needle (15) which is guided in an axially movable manner and which is surrounded by a nozzle chamber (19), a high-pressure bore (8) that connects the high-pressure accumulator (6) to the injection nozzle (2), and a resonator bore (20), connected in parallel to the high-pressure line (8), that is connected to the injection nozzle (2) and opens into the high-pressure accumulator (6) via a resonator throttle (21). The high-pressure bore (8) comprises a first section (8') adjoining the high-pressure accumulator (6) and a second section (8'') opening into the injection nozzle (2), the first section (8') having a greater flow cross-section than the second section (8'').