Dual-Fuel Injector Control Valve Sealing With a Flexible Disc-Flange
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Solution Overview
Problem
Diesel fuel injectors experience imperfect sealing due to biased contact areas and high pressures resulting from dimensional tolerances, leading to potential damage.
Innovation Solution
A control valve with a spool assembly featuring an annular groove and disc-flange design, allowing for slight deflection and improved sealing contact, is integrated into the dual-fuel injector to manage the injection of diesel fuel and compressed natural gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dimensional tolerances are maintained within standard limits, then manufacturing cost is reduced, but sealing performance deteriorates due to biased contact areas
Solution Approach 1:
The spool is designed with a thin disc-flange at its upper end that acts as a flexible element. This thin flange can deflect and adapt to surface irregularities, ensuring uniform sealing contact even when dimensional tolerances cause misalignment between the spool and complementary face. The flexibility compensates for manufacturing variations without requiring tighter tolerances.
Solution Approach 2:
The invention changes the physical state of the spool's upper end region by making it thin and flexible rather than rigid. This parameter change allows the sealing surface to adapt dynamically, transforming the sealing mechanism from one dependent on precise dimensional control to one that tolerates variations through elastic deflection.
2Speed
If contact area is reduced to a small region, then sealing responsiveness is improved, but contacting pressure increases excessively causing damage
Solution Approach 1:
The thin disc-flange distributes the contact pressure across its entire perimeter rather than concentrating it at a single point or small area. The flexible nature of this thin element allows it to conform to the mating surface while spreading the load, reducing peak pressures from 900 MPa to below 400 MPa while maintaining effective sealing.
Solution Approach 2:
The upper end region of the spool serves multiple functions: it provides the sealing surface, distributes pressure, and compensates for misalignment through deflection. This multi-functional design eliminates the need for separate alignment features or pressure-distributing elements.
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 enhances sealing performance by distributing contact pressure evenly across the edge area, reducing peak pressure from 900 MPa to less than 400 MPa and ensuring consistent sealing contact, thus preventing damage and improving injector efficiency.
Implementation Method 1
a disc-flange comprising the peripheral edge area of the upper end face may be defined between said upper end face and said groove, said disc-flange being adapted to allow a slight deflection when said upper end face is pressed in sealing contact against said complementary face
Data Source
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AI summary
A control valve (34) adapted to be arranged in a fuel injector having a body (94) defining a hydraulic bore (112) in which is axially guided an armature- and-spool assembly (98) opens in said upper end face (86), the spool (108) of said assembly having an upper end region (124) defining an upper end face adapted to be pressed in sealing contact against a complementary face. The upper end region (124) is further provided with an annular groove arranged in close vicinity to said upper end face.