Single-Piece Fuel Flow Limiting Valve Piston Design
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Solution Overview
Problem
Existing fuel flow limiting valves for large internal combustion engines, particularly in common rail injection systems, face challenges such as high production costs, reduced reliability due to complex machining requirements, and significant pressure drop, which affect the dynamic behavior and efficiency of fuel injection.
Innovation Solution
A fuel flow limiting valve design featuring a single-piece construction with a valve housing and piston, incorporating a helical spring and integrated sealing surfaces, reduces the number of components and machining operations, enhancing the sealing efficiency and reducing inertia and pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-component piston with separate closing element is used, then the sealing function is achieved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the piston body and closing element into a single integral component. The piston features a unified structure where the closing surface is formed as part of the piston body itself, eliminating the need for separate closing elements and reducing assembly complexity while maintaining sealing functionality.
Solution Approach 2:
The single-piece piston performs multiple functions simultaneously: it acts as both the moving component that responds to pressure differential and the sealing element that closes the orifice. The integral design combines flow control and sealing functions in one component, reducing the overall device complexity.
2Reliability
If precision machining operations are performed to ensure coaxiality of seats and guide surface, then the sealing is improved, but the production cost and manufacturing time increase
Solution Approach 1:
By combining all sealing surfaces and guide surfaces into a single piston component, the patent reduces the number of precision machining operations required. The unified structure allows for more straightforward machining processes compared to coordinating multiple separate components, thereby reducing production costs while maintaining sealing efficiency.
3Productivity
If the piston mass is reduced, then the pressure drop required to accelerate the piston decreases, but the structural integrity and sealing capability may be compromised
Solution Approach 1:
The piston is designed with an optimized geometry that segments the material distribution to minimize mass while maintaining structural integrity. The streamlined shape and integrated design reduce unnecessary material while preserving the strength required for reliable operation and sealing capability.
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 design decreases production costs, increases operational reliability, and improves the dynamic behavior by reducing the pressure drop required to accelerate the piston, enabling higher pressure injections and preventing excessive fuel discharge.
Implementation Method 1
A helical spring in compression pushes the valve piston towards the inlet channel of the fuel flow
Implementation Method 2
The pressure drop between the upstream and downstream chambers of the piston is such so that it balances, in each position and instant, the spring force and the inertia of the piston itself
Implementation Method 3
The valve piston carries a closing element in pin-form, elongated in the longitudinal direction and having sealing surfaces at its opposite ends, which cooperate with the inlet valve seat and the outlet valve seat, respectively
Data Source
AI summary
A fuel flow limiting valve for large internal combustion engines, comprising: - a valve housing (12) including an inner cylindrical surface (24) surrounding a valve chamber (14), an inlet channel (28) with an inlet valve seat (30), an outlet channel (38) with an outlet valve seat (40), - a valve piston (42) housed in said valve chamber (14) and having a base wall (44) and a cylindrical wall (46), which is guided in a longitudinal direction (A) from said inner cylindrical surface (24) of the valve housing (12), the valve piston (42) having a first sealing surface (52) cooperating with the inlet valve seat (30) and a second sealing surface (54) cooperating with the outlet valve seat (40), the valve piston (42) being movable in said longitudinal direction (A) between a first position in which the first sealing surface (52) closes the inlet valve seat (30) and a second position in which the second sealing surface (54) closes the outlet valve seat (40), and - an elastic element (58) arranged between the housing (12) and the valve piston (42) and tending to push the valve piston (42) towards said first position, wherein the first and the second sealing surfaces (52, 54) are machined directly onto said base wall (44) of the valve piston (42) and wherein the valve housing (12) comprises a pin formation (34), which extends in the longitudinal direction within said valve chamber (14).