Common-Rail Injector Control Valve Seat Geometry
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Solution Overview
Problem
Common-rail diesel engine injectors face challenges in reducing fuel leakage and improving energy efficiency due to the inverse proportionality of displacement and force in piezo actuators, leading to increased driving force for nozzle closing and reduced controllability of fuel injection.
Innovation Solution
A three-way valve structure with a slide pin member and throttle portion is used to reduce the driving force for closing the high-pressure side seat by utilizing the control chamber pressure as an assistance force, allowing for a larger high-pressure side seat diameter and improved nozzle closing speed, while minimizing fuel leakage and enhancing energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the high-pressure side seat opening area is increased to increase nozzle closing speed, then nozzle closing speed is improved, but the closing driving force becomes greater reducing energy efficiency
Solution Approach 1:
The invention applies counterpressure from the control chamber to offset the closing driving force on the high-pressure side seat. The control chamber receives pressure from the low-pressure channel that acts in the opening direction, counterbalancing the closing force and reducing the net driving force required, thereby improving energy efficiency while maintaining adequate closing speed.
Solution Approach 2:
The control chamber serves as an intermediary mechanism between the low-pressure channel and the high-pressure side seat. It transmits and modulates the pressure from the low-pressure channel to apply a counteracting force on the high-pressure side seat, enabling indirect control of the closing force and improving overall system efficiency.
2Productivity
If a pressure balance valve is used to operate the system efficiently, then system efficiency is improved, but fuel leakage occurs through the sliding portion increasing fuel temperature and deterioration
Solution Approach 1:
The invention extracts and eliminates the pressure balance valve component that causes fuel leakage. By removing this sliding portion entirely and replacing it with a valve element that directly communicates between channels without sliding seals, the source of fuel leakage is eliminated while maintaining system efficiency through direct pressure control.
Solution Approach 2:
The invention replaces the pressure balance valve with a simpler valve element structure that sacrifices the sliding mechanism (which causes leakage) in exchange for a more reliable, maintenance-free design. The new structure accepts some functional limitations but eliminates the harmful leakage effect completely.
3Adaptability or versatility
If a spherical valve element is used with separate high-pressure and low-pressure side seat members, then the valve can accommodate positional shifts, but leakage occurs due to positional shifts of the two members
Solution Approach 1:
The invention merges the high-pressure side seat and low-pressure side seat into a single integrated seat structure. This eliminates the interface between two separate members where leakage occurs, while the spherical valve element can still accommodate positional shifts of the entire integrated seat assembly, maintaining both adaptability and sealing reliability.
Solution Approach 2:
The invention converts the potential harm of positional shifts into a benefit by designing a spherical valve element that intentionally accommodates these shifts. Instead of trying to prevent positional shifts, the design accepts them and uses the spherical geometry to maintain sealing contact, transforming a source of leakage into a feature that enhances adaptability.
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 configuration decreases the nozzle opening speed, increases nozzle closing speed, and improves injection controllability and energy efficiency with a simple design, effectively addressing the limitations of existing technologies.
Implementation Method 1
a piezo actuator is used as the actuator. When electrically energized, the piezo actuator extends to release the valve element from the low-pressure side seat
Implementation Method 2
the pressure of the control chamber in communication with the valve chamber is exerted as an assistance force so that a high-pressure side seat closing load becomes less than or equal to the opening load of the low-pressure side seat
Implementation Method 3
A space formed around the pin-shaped extremity, between a sliding portion of the slide pin member and the low-pressure side seat, is connected to a low-pressure channel through a throttle portion
Data Source
AI summary
A common rail injector for injecting fuel through a high-pressure channel includes a control chamber, a control valve, and a drive unit. The control chamber applies pressure to a nozzle needle. The control valve switches communication of the control chamber between the high-pressure channel and a low-pressure channel. The drive unit selectively sets a valve element of the control valve on a low-pressure side seat or a high-pressure side seat. The drive unit has an actuator and a slide pin member. The slide pin member slides inside a slide hole to transmit a force to the valve element. A diameter of the low-pressure side seat is less than or equal to a diameter of the high-pressure side seat. The pressure in the control chamber is exerted as an assistance force, so that a high-pressure side seat closing load becomes less than or equal to a low-pressure side seat opening load.