Fuel Injection Valve Collar Gap Throttle Design
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Solution Overview
Problem
High-pressure fuel injection in internal combustion engines leads to increased hydraulic forces making it difficult to control the valve needle, resulting in leakage and increased fuel consumption, and existing throttle solutions are difficult to manufacture and sensitive to tolerance deviations.
Innovation Solution
A fuel injection valve with a collar on the valve needle featuring a rounded or conical inlet-side surface and a conical or rounded outlet-side surface, along with a cylindrical section, which forms a gap throttle that is easy to manufacture and insensitive to tolerance deviations, ensuring stable flow separation and adjustable throttling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a low-pressure stage is provided to achieve rapid valve needle closing, then the closing force is improved, but fuel leakage increases and fuel consumption increases
Solution Approach 1:
The patent removes the low-pressure stage from the fuel injection valve system. Instead of using a low-pressure control chamber to generate closing force, the invention relies on the direct action of the valve spring and the hydraulic balance between fuel pressure and spring force, thereby eliminating the source of fuel leakage while maintaining rapid closing capability
Solution Approach 2:
The patent changes the pressure parameters in the control chamber by eliminating the low-pressure stage. The control chamber now operates at high pressure directly from the fuel rail, and the closing force is generated through the balanced interaction between this high pressure and the valve spring, rather than through a pressure differential created by a low-pressure stage
2Force
If a throttle collar with sharp edge is used to reduce hydraulic force, then the closing force is improved, but manufacturing difficulty increases and tolerance sensitivity increases
Solution Approach 1:
The patent replaces the sharp-edged throttle collar with a collar featuring a rounded edge. This curvature modification eliminates the manufacturing complexity and tolerance sensitivity associated with sharp edges, while still achieving the desired flow separation and pressure differential effect to control the hydraulic force on the valve needle
Solution Approach 2:
The patent applies a localized geometric modification (rounded edge) specifically at the throttle collar position where flow separation occurs. This local quality change optimizes the flow characteristics and pressure distribution without affecting the overall structure, making the component easier to manufacture with standard tolerances
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
The solution allows for efficient and rapid closure of the valve needle, reducing leakage and fuel consumption while being robust to manufacturing variations and fuel properties, maintaining effective throttling independent of Reynolds number and temperature.
Implementation Method 1
a surface designed in this way is stable against flow detachments, so that no cavitation phenomena occur that influence the flow resistance at the gap throttle
Implementation Method 2
no cavitation phenomena occur that influence the flow resistance at the gap throttle
Implementation Method 3
When the injection valve is open, ie when the valve needle has lifted off the valve seat, this results in a pressure loss, so that the pressure downstream of this throttle gap is lower than upstream
Data Source
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AI summary
Fuel injection valve for internal combustion engines having a valve body (1), in which a pressure chamber (5) is formed, in which a valve needle (3) is arranged such that it can be displaced longitudinally, which valve needle (3) interacts by way of a valve sealing surface (11) which is formed on the valve needle (3) with a valve seat (9) which delimits the pressure chamber (5). As a result of the interaction of the valve needle (3) with the valve seat (9), a fuel flow to at least one injection opening (7) is made possible or interrupted, wherein the fuel flow flows through between the valve needle (3) and the wall of the pressure chamber (5) to the injection openings (7). A collar (17) is formed on the valve needle (3), with the result that a gap throttle (15) is formed between the wall of the pressure chamber (5) and the collar (17), wherein the collar (17) has an inlet-side surface (20) and an outlet-side surface (24), wherein the inlet-side surface (20) is of rounded or conical configuration.