Dispensing Valve Preload Profile for Reliable Fuel Shut-Off
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Solution Overview
Problem
Existing dispensing valves face issues with uncontrolled fuel leakage during full-hose operation due to manufacturing tolerances and high testing requirements, especially when the pressure in the fuel hose does not drop below the minimum required for automatic shut-off, and the sealing capacity is reduced.
Innovation Solution
The dispensing valve features a pre-tensioning device that generates a discontinuous opening characteristic, reducing the closing force in a first opening cross-sectional area and ensuring the main valve assembly opens easily with low pressure, while requiring a higher pressure differential to further increase the opening cross-section, thus enhancing the reliability of the automatic shut-off mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main valve is forced into the closed position at an angle to reduce sealing capacity, then pressure can dissipate in a controlled manner during full-hose operation, but the components require tight manufacturing tolerances and high level of testing
Solution Approach 1:
The patent applies the dynamics principle by making the closing force of the pre-tensioning device variable rather than constant. The closing force adapts dynamically based on the opening cross-sectional area: it is reduced in the first opening range to allow controlled pressure dissipation, and increased in the second opening range to ensure reliable shut-off. This dynamic adjustment eliminates the need for tight manufacturing tolerances while maintaining reliability.
Solution Approach 2:
The patent changes the parameter of closing force according to the opening state of the valve. By varying the closing force in different opening ranges (reduced force in the first range, increased force in the second range), the system achieves both controlled pressure dissipation and reliable shut-off without requiring precise manufacturing tolerances.
2Ease of operation
If the main valve assembly opens easily with low pressure, then controlled pressure reduction is achieved during full-hose operation, but a higher pressure differential is required to maintain the open state
Solution Approach 1:
The pre-tensioning device dynamically adjusts its closing force based on the valve's opening position. In the first opening range, the reduced closing force allows the valve to open easily with low pressure. In the second opening range, the increased closing force ensures that sufficient pressure differential is required to maintain the open state, preventing uncontrolled leakage.
Solution Approach 2:
The patent applies partial action by reducing the closing force only in the first opening range where controlled pressure dissipation is needed, while maintaining or increasing the closing force in the second opening range where reliable shut-off is required. This selective adjustment of closing force achieves both ease of opening and pressure control.
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 allows for controlled pressure reduction and reliable shut-off, even during full-hose operation, by ensuring the main valve assembly opens with low pressure and requires a higher pressure to maintain the open state, thereby preventing uncontrolled fuel leakage.
Implementation Method 1
The pre-tensioning device generates an increased back pressure upstream of the main valve in the known dispensing nozzle during fluid delivery. This pressure dissipates after the fuel pump is switched off. The pre-tensioning device thus contributes to generating a sufficient pressure differential, which can be utilized in a known manner within the automatic shut-off device to ensure reliable shutdown.
Implementation Method 2
an automatic safety shut-off designed to move the main valve assembly to a closed position, regardless of the position of the control lever, when the fluid pressure at the inlet falls below a minimum value
Data Source
Figure 1
Figure 2~3B
Figure 4~7A
AI summary
Filling nozzle for delivering a fluid, comprising an inlet (13) for connection of a fluid feed line, an outlet (14), a main conduit (15) connecting the inlet to the outlet, a main valve device (16) for controlling a flow of fluid through the main conduit (15), a control lever (17) for actuating the main valve device (16), an automatic safety shut-off designed to move the main valve device (16) to a closed position independently of a position of the control lever (17) when a fluid pressure at the inlet (13) falls below a minimum value, and comprising a preloading device (18) which preloads the main valve device (16) into the closed position and effects a variable opening cross-section of the main valve device (16) depending on a fluid pressure at the inlet. According to the invention, the preloading device (18) is designed to produce a discontinuous opening characteristic of the main valve device (16) in such a way that a closing force acting on a valve body (20, 20', 20", 22) of the main valve device is reduced in a first opening cross-section range extending from the closed position of the main valve device (16) to a limit opening cross-section.