Pneumatic Pressure Valve Sense Line Flow Restriction
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Solution Overview
Problem
Pneumatic pressure regulation valves in aerospace applications, such as hot air-based de-icing systems for gas turbine engines, face instability issues due to large volumes of connecting tubes or pipes in the sense line, leading to high-frequency oscillations of the valve piston and accelerated wear of seals and piston bore.
Innovation Solution
A flow restriction is introduced upstream of the relief valve to decouple the large volume of the sense line from the regulation chamber, ensuring that piston movement results in a greater pressure variation, thereby enhancing damping capability and maintaining stability without interfering with pressure regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sense line volume is large to accommodate remote control elements, then the control range is extended, but the valve stability deteriorates due to high-frequency oscillations
Solution Approach 1:
The sense line is segmented into two separate volumes by the flow restriction: a first volume between the inlet and the flow restriction, and a second volume between the flow restriction and the relief valve. This segmentation isolates the regulation chamber from the large remote sense line volume, preventing oscillations while maintaining remote control capability.
Solution Approach 2:
A flow restriction is introduced as an intermediary element in the sense line. This flow restriction acts as a buffer that decouples the regulation chamber from the large-volume remote sense line, allowing remote control elements to be positioned far from the valve without causing instability.
2Stability of the object's composition
If the flow restriction is small to decouple the sense line volume, then the valve stability is improved, but the pressure regulation may be interfered with
Solution Approach 1:
The flow restriction is positioned at a specific location in the sense line (between the inlet and the relief valve) rather than uniformly throughout. This localized placement ensures that the restriction only affects the coupling between the regulation chamber and the remote sense line, while leaving the pressure regulation function between the regulation chamber and relief valve intact.
3Ease of operation
If the sense line volume is large for remote positioning, then the installation flexibility is increased, but the seal and piston bore wear accelerates due to oscillations
Solution Approach 1:
By segmenting the sense line volume into two separate volumes with the flow restriction, the patent eliminates the harmful oscillations that cause wear while preserving the ability to position control elements remotely, thus maintaining installation flexibility without the detrimental effects.
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 flow restriction stabilizes the valve operation by reducing oscillations and preventing excessive wear, ensuring reliable and efficient pneumatic pressure regulation, even in systems with remote control elements and multiple valves in series.
Implementation Method 1
piston movement results in a greater pressure variation, thereby enhancing damping capability and maintaining stability
Implementation Method 2
enhancing damping capability and maintaining stability without interfering with pressure regulation
Data Source
Figure 1~2a
Figure 2b~3
Figure 4~5
AI summary
A pneumatic pressure regulation valve comprising: a valve inlet; a valve outlet; a piston arranged to control gas flow from the inlet to the outlet; a sense line fluidly connecting the inlet to a pressure regulation chamber and with a pressure relief valve connected thereto to limit the pressure in the pressure regulation chamber; wherein the piston is arranged between the pressure regulation chamber and the valve outlet such that the position of the piston is determined by the relative pressures in the regulation chamber and the valve outlet and the position of the piston controls the flow from the valve inlet to the valve outlet; wherein the sense line comprises a flow restriction upstream of the pressure relief valve . The flow restriction addresses instability that can arise from large volumes of connecting tubes or pipes in the sense line. When the volume of the sense line pipework is large relative to the regulation chamber volume, instability can arise in the feedback loop that regulates the output pressure. The resultant high frequency oscillations accelerate wear of the seals and bore. Large sense line volumes may arise where control elements are remote from the valve, e.g. in hot air based de-icing systems for an aircraft engine. The flow restriction decouples the large volume of the sense line from the main volume of the regulation chamber, thus avoiding instability. As the flow restriction is upstream of the relief valve it does not interfere with the pressure communication between the regulation chamber and the relief valve and therefore does not interfere with the pressure regulation which could result in a reduction in the expected output pressure of the regulation valve.