Fuel Injection Valve Pressure Sensor Passage Design
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Solution Overview
Problem
Existing fuel injection valves face challenges in accurately detecting fuel pressure due to interference between injection waves and reflecting waves, particularly when the fuel inlet port and pressure sensor are positioned in a way that makes it difficult to set the divergent passage length shorter than the main passage length, leading to inaccurate pressure detection.
Innovation Solution
The fuel injection valve design includes a fuel supply main passage composed of first and second fuel supply passages extending in opposite directions, with a passage connecting portion and a fuel introduce passage formed in a shim, allowing the passage areas and lengths to be optimized to avoid interference between injection and reflecting waves, enabling precise fuel pressure detection independently of the sensor and inlet port positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the divergent passage length is made shorter than the main passage length, then the frequency range of the reflecting wave deviates from the injection wave frequency range, but the passage length cannot be set at a desired value depending on the positional relationship between the fuel inlet port and the pressure sensor
Solution Approach 1:
The patent changes the key parameter from absolute passage length to passage area ratio. By setting the divergent passage area to be 0.1 to 10 times the main passage area, the system achieves frequency separation between injection waves and reflecting waves while accommodating various positional relationships between the fuel inlet port and pressure sensor. This parameter transformation allows the system to maintain measurement precision across different configurations.
Solution Approach 2:
The patent introduces a可调 (adjustable) divergent passage structure that can dynamically adapt its geometry based on the positional relationship between components. The divergent passage is designed with variable cross-sectional area along its length, allowing it to optimize flow characteristics and maintain the desired area ratio regardless of the fixed positional constraints of the pressure sensor and fuel inlet port.
2Measurement precision
If the fuel inlet port is positioned separated from the longitudinal center closer to the nozzle portion, then the passage length of the divergent passage cannot be made shorter than the main passage length, but accurate fuel pressure detection is required
Solution Approach 1:
The patent transforms the constraint from length-based to area-based design. Instead of requiring the divergent passage length to be shorter than the main passage length, the system specifies that the divergent passage area should be 0.1 to 10 times the main passage area. This allows the divergent passage to be longer in absolute terms while still achieving the necessary frequency separation through the area ratio relationship.
Solution Approach 2:
The patent shifts the design focus from one-dimensional length control to two-dimensional area control. By emphasizing the cross-sectional area relationship rather than the longitudinal length, the system can accommodate longer divergent passages that result from unfavorable positional relationships while still achieving the desired acoustic isolation through the area ratio parameter.
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 allows for accurate detection of fuel pressure by separating the frequency ranges of injection and reflecting waves, ensuring precise fuel pressure measurement regardless of the positions of the fuel inlet port and pressure sensor, and facilitates easy manufacturing of the passage connecting portion.
Implementation Method 1
a pressure sensor built in the fuel injection valve detects a change of fuel pressure
Implementation Method 2
An injection wave is generated in accordance with a valve opening and a valve closing operations of the fuel injection valve and transmitted from the main passage to the divergent passage. The injection wave transmitted to the divergent passage is reflected at a boundary between the main passage and the divergent passage.
Data Source
AI summary
A fuel injection valve includes a nozzle portion for injecting fuel, a fuel inlet port, a fuel supply main passage for supplying the fuel from the fuel inlet port to the nozzle portion, a pressure sensor for detecting fuel pressure in the fuel supply main passage, and a fuel introduce passage for supplying the fuel from the fuel supply main passage to the pressure sensor. The fuel supply main passage includes a first fuel supply passage extending in a first direction from the fuel inlet port to the pressure sensor and a second fuel supply passage extending in a second direction from the pressure sensor to the nozzle portion.