Fuel Injection Valve Common Orifice Pressure Pulsation
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Solution Overview
Problem
Conventional fuel injection valves experience pressure pulsation in the control chamber during nozzle opening, causing the needle to resonate and resulting in a non-linear relationship between drive pulse duration and fuel injection quantity.
Innovation Solution
A fuel injection valve design featuring a common orifice in the communication passage between the control and valve chambers, which restricts flow and reduces pressure pulsation, allowing independent setting of nozzle opening and closing speeds through separate orifices for high and low-pressure fuel passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high pressure fuel is introduced into the control chamber through the communication passage during valve opening, then the valve opening speed can be controlled independently, but pressure pulsation is generated in the control chamber causing needle resonance and non-linear injection characteristics
Solution Approach 1:
The communication passage is segmented into two separate passages: a first communication passage for introducing high-pressure fuel during valve closing, and a second communication passage for discharging fuel during valve opening. This segmentation prevents pressure pulsation from affecting the needle while maintaining independent control of valve speeds through separate orifice control.
Solution Approach 2:
The harmful pressure pulsation effect is extracted and isolated by separating the fuel introduction and discharge paths. The first communication passage extracts the high-pressure fuel introduction function, while the second communication passage extracts the fuel discharge function, preventing their harmful interaction during valve opening.
2Speed
If the communication passage allows free flow between control chamber and high-pressure fuel passage, then rapid valve opening is achieved, but pressure pulsation causes needle oscillation and lift amount deviation
Solution Approach 1:
Different local qualities are applied to different passages: the first communication passage has a first orifice with specific flow characteristics for controlled high-pressure fuel introduction, while the second communication passage has a second orifice with different flow characteristics for controlled fuel discharge. This local differentiation enables both rapid response and precise control.
Solution Approach 2:
The communication passages with controlled orifices act as intermediaries between the high-pressure fuel passage and the control chamber. These intermediaries buffer and regulate the pressure transmission, preventing direct pressure pulsation from reaching the needle while still enabling controlled valve speed adjustment.
3Adaptability or versatility
If separate orifices are used for controlling valve opening and closing speeds, then independent speed setting is achieved, but device complexity increases
Solution Approach 1:
The communication passages serve multiple functions: they control valve opening speed through the second orifice, control valve closing speed through the first orifice, and isolate pressure pulsation from the needle. This multi-functionality reduces the need for additional separate components, offsetting the complexity of having separate passages.
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 ensures the needle lift is proportional to the drive pulse duration, achieving a linear characteristic curve for fuel injection quantity versus drive pulse duration, while maintaining high flexibility in setting valve speeds.
Implementation Method 1
pressure pulsation is generated in the control chamber at a time of a valve opening of the nozzle
Implementation Method 2
The communication passage has a common orifice
Implementation Method 3
the needle is biased in a valve closing direction for closing the injection orifice by pressure of fuel in the control chamber
Implementation Method 4
High pressure fuel in the high-pressure fuel passage is introduced into the control chamber only through the communication passage
Data Source
AI summary
A fuel injection valve includes a valve chamber, a control valve, an actuator, a control chamber, and a nozzle. The control valve is provided in the valve chamber. The actuator actuates the control valve. The control chamber is always communicated with the valve chamber through a communication passage. The nozzle has a needle for opening and closing an injection orifice, wherein the needle is biased in a valve closing direction for closing the injection orifice by pressure of fuel in the control chamber. High pressure fuel in a high-pressure fuel passage is introduced into the control chamber only through the communication passage in a state, where communication between the valve chamber and the high-pressure fuel passage is allowed by the control valve. The communication passage has a common orifice.