Dual-Needle Shut-Off Valve for High-Pressure Fuel Cell Tanks
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Solution Overview
Problem
High-pressure gas tank shut-off valves in fuel cell systems require high opening forces due to the high-pressure differential, making them difficult to miniaturize and increasing wear.
Innovation Solution
A shut-off valve design with a servo valve needle and a main valve needle, both actuated by the same coil, allows for reliable opening at both low and high pressure levels, using a pressure gradient to reduce the required opening force and enable a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-powered closed solenoid design is used with high-pressure preloading, then the valve can maintain reliable sealing at high pressure, but the opening force required becomes very high making miniaturization difficult
Solution Approach 1:
The valve is divided into two independent sealing elements (first sealing element and second sealing element) that can be opened sequentially. The first sealing element seals the high-pressure side, while the second sealing element seals the low-pressure side. This segmentation allows the high opening force to be distributed across two separate sealing events rather than one, enabling miniaturization while maintaining reliable sealing.
Solution Approach 2:
The valve stem includes a through-hole that connects the secondary chamber to the inlet, allowing pressure to be applied to the second sealing element in advance. This preliminary pressure application creates an opening force on the second sealing element that acts in the opposite direction to the closing force on the first sealing element, reducing the total opening force required from the coil.
2Strength
If the valve is designed to withstand high pressure differentials, then it can operate in high-pressure tank applications, but the valve size increases making miniaturization difficult
Solution Approach 1:
The valve separates the high-pressure sealing function (first sealing element) from the low-pressure sealing function (second sealing element). This allows each sealing element to be optimized for its specific pressure level, enabling the use of smaller, more compact components rather than requiring a single large valve designed for the full pressure differential.
Solution Approach 2:
The valve changes the pressure parameter applied to different sealing elements at different times during operation. The first sealing element handles high-pressure sealing, while the second sealing element handles low-pressure sealing. This parameter change allows the valve to withstand high pressure differentials while maintaining a compact size suitable for miniaturization.
3Device complexity
If a single sealing element is used to seal both high-pressure and low-pressure sides, then the valve structure is simpler, but the opening force required is very high due to the full pressure differential
Solution Approach 1:
Instead of using a single sealing element, the valve employs two separate sealing elements (first and second sealing elements) positioned at different pressure levels. This segmentation reduces the pressure differential that each sealing element must overcome individually, thereby reducing the opening force required from the coil while only moderately increasing structural complexity.
Solution Approach 2:
The valve stem acts as an intermediary structure that connects both sealing elements and transmits the coil's magnetic force to both elements simultaneously. The through-hole in the valve stem serves as a mediator to apply pressure to the second sealing element, creating an opening force that counteracts the closing force on the first sealing element, thereby reducing the total opening force required.
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 achieves reliable fuel supply with reduced wear by minimizing the force needed to open the valve, allowing for a compact and efficient shut-off valve that can withstand large pressure differentials.
Implementation Method 1
an electrical coil which is accommodated in the partition and surrounds the guide hole, and a servo valve needle which is arranged in the control chamber, is preloaded along the longitudinal axis into a closed position... and can be moved, by means of a magnetic field which can be generated by the coil
Implementation Method 2
a valve needle is preloaded against a sealing seat by a spring
Implementation Method 3
The valve stem comprises a first opening which forms a fluidic connection between the inlet and a high-pressure side of the first sealing element. A closing force is thereby applied to the first sealing element as a result of the pressure that is applied to the inlet.
Data Source
AI summary
The invention relates to a shut-off valve comprising: a housing which has an inlet opening, an outlet opening and a control opening, wherein the housing defines an inner space extending along a longitudinal axis and has a partition which divides the inner space into an outlet chamber and a control chamber and has a guide hole which extends between the outlet chamber and the control chamber; an electrical coil which is accommodated in the partition and surrounds the guide hole; a servo valve needle which is arranged in the control chamber, is preloaded along the longitudinal axis into a closed position in which it seals the control opening, and can be moved, by means of a magnetic field which can be generated by the coil, into an open position in which it exposes the control opening and abuts the partition, wherein the servo valve needle has a connecting channel which connects the control chamber to the guide hole in the open position of the servo valve needle; and a main valve needle which is movably guided in the guide hole along the longitudinal axis, is preloaded along the longitudinal axis into a closed position in which it seals the outlet opening, and, when the servo valve needle is arranged in its open position, can be moved, by means of the magnetic field which can be generated by the coil, into an open position in which it exposes the outlet opening.