Extraction Valve Intermediate Volume Reduces Seat Stress
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Solution Overview
Problem
Existing extraction valves for overpressurized gases, particularly hydrogen, face challenges in achieving long-term reliability and durability due to insufficient sealing and premature damage from high pressure fluctuations and abrasive particles, leading to issues with tightness and valve seat wear.
Innovation Solution
The extraction valve design features an intermediate volume connected between the inflow chamber and the valve seat, reducing mechanical stress on the valve seat by diverting gas flow axially and using an annular intermediate element with bores for uniform gas distribution, along with a sealing lip protected by a protrusion and activation volume for enhanced sealing and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing elements are omitted and the valve body and valve seat are made of single metallic material, then tightness is improved, but the valve seat becomes damaged after a few thousand switching cycles due to high pressure ratios and high flow velocity
Solution Approach 1:
The valve seat region is segmented into a protective coating layer applied on the valve body surface. This coating layer specifically protects the valve seat from wear and damage caused by high flow velocity and pressure fluctuations, while the metallic valve body maintains its tightness. The coating and valve body work together to resolve the contradiction between tightness and durability.
Solution Approach 2:
A composite structure is created by applying a protective coating material on the metallic valve body in the valve seat region. This composite structure combines the advantages of metallic tightness with the wear resistance and durability of specialized coating materials, allowing the valve seat to withstand high pressure ratios and flow velocities for thousands of cycles.
2Device complexity
If the inflow chamber is directly connected to the valve seat region, then the structure is simpler, but the mechanical stress on the valve seat becomes enormous due to sudden pressure relaxation from 70 MPa to 20-40 MPa
Solution Approach 1:
An intermediate element with flow distribution bores is introduced as a mediator between the inflow chamber and the valve seat region. This intermediate element distributes the gas flow through multiple bores, reducing the sudden pressure relaxation and mechanical stress on the valve seat. The intermediate element acts as a buffer that gradually transitions the pressure from 70 MPa to 20-40 MPa, protecting the valve seat while maintaining reasonable structural complexity.
3Device complexity
If the extraction piston is actuated directly by electromagnetic coil, then the actuation system is simpler, but the sealing against hydrogen becomes difficult to maintain with high cycle stability
Solution Approach 1:
A pilot bore system is introduced as an intermediary mechanism between the electromagnetic coil and the extraction piston. The pilot bore uses gas pressure to actuate the extraction piston, providing better control and sealing against hydrogen. This intermediary pressure actuation system maintains high cycle stability and sealing reliability while keeping the overall actuation system relatively simple.
Data Source
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AI summary
The invention concerns an extraction valve (4) for overpressurised gas flowing from a compressed gas reservoir (2), having a valve seat carrier (30), Including a conical valve seat (31) emerging centrally into an outflow chamber (20), having an extraction piston (17), which is mobile in its axial direction (4) at least indirectly via an electromagnetic coil (12), and which includes a valve body (32) cooperating with the valve seat (31), and an inflow chamber (10) for the pressurised gas, The extraction valve according to the invention is characterised in that the inflow chamber (10) is designed totally or partially on the circumference of a central axis (A) of the extraction piston (17) and is connected in the axial direction of the extraction piston (17) against a flow direction (E) of the gas when the extraction piston (17) is in open position, between the valve seat (31 ) and the valve body (32) via an intermediate connection (bores 34) with an intermediate volume (35), which comprises for its own part a connection (opening 38) with the region In which the valve seat (31 ) and the valve body (32) co-operate.