Aircraft Fuel Valve Unit with Pressure-Stable Pilot Fuel Control
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Solution Overview
Problem
Existing valve units for gas turbine fuel supply systems experience unpredictable operation due to pressure fluctuations between the pilot and main chambers, leading to metastable positions and intermittent fuel supply to the pilot stage, which impedes smooth, low-emission combustion.
Innovation Solution
A valve unit design with a second chamber featuring a further inlet and outlet, along with pressure regulating means, ensures stable fuel supply by maintaining a higher pressure in the pilot chamber, preventing sudden pressure changes and ensuring reliable operation through fail-safe configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second outlet is closed by the actuating body to prevent fuel flow to the pilot stage, then fuel supply control is improved, but pressure fluctuations cause the actuating body to reciprocate and repeatedly open the outlet, leading to unstable operation
Solution Approach 1:
A cushioning chamber is introduced as an intermediary between the second chamber and the second outlet. This cushioning chamber absorbs pressure fluctuations and prevents them from directly acting on the actuating body, thereby eliminating the reciprocating motion and stabilizing the outlet closure.
Solution Approach 2:
The cushioning chamber is pre-filled with fuel that acts as a cushioning medium. When pressure fluctuations occur in the second chamber, this pre-positioned cushioning fuel absorbs the pressure variations before they can cause the actuating body to move, preventing premature opening of the closed outlet.
2Stability of the object's composition
If pressure regulating means are added to maintain stable pressure in the second chamber, then operation stability is improved, but device complexity increases
Solution Approach 1:
The cushioning chamber is designed to automatically compensate for pressure fluctuations using the compressibility of the fuel it contains. The system self-regulates pressure without requiring external pressure regulating means, thereby maintaining stability while avoiding additional complex components.
Solution Approach 2:
The invention utilizes the hydraulic properties of fuel, specifically its compressibility, to create a cushioning effect. The cushioning chamber filled with fuel acts as a hydraulic buffer that absorbs pressure variations, providing stable operation through fluid mechanics rather than mechanical pressure regulation devices.
3Productivity
If the actuating body is positioned to close the second outlet, then pilot stage fuel supply is stopped, but pressure differences cause unpredictable positioning and intermittent fuel flow
Solution Approach 1:
The cushioning chamber serves as a mediator that decouples the pressure fluctuations in the second chamber from the actuating body positioning. By absorbing these fluctuations, it ensures the actuating body remains steadily positioned, guaranteeing predictable and reliable operation of the fuel supply system.
Solution Approach 2:
The cushioning chamber is pre-configured with fuel to absorb pressure variations before they can affect the actuating body position. This beforehand cushioning prevents unpredictable positioning and ensures consistent, reliable operation of the fuel supply 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
The design stabilizes fuel supply, ensuring smooth, low-emission, and predictable operation of the combustion chamber by preventing pressure fluctuations and maintaining fuel flow during normal and failure conditions.
Implementation Method 1
an elastic return element arranged in one of the chambers, in particular in the second chamber, and coupled to the actuating body in a force-transmitting manner, in particular a spring arrangement
Implementation Method 2
a spring arrangement, and the valve unit is designed such that an actuating force for positioning the actuating body within the valve chamber is generated by an interaction of a restoring force of the restoring element
Implementation Method 3
an actuating force for positioning the actuating body within the valve chamber is generated by an interaction of a restoring force of the restoring element with a pressure difference existing between the chambers, wherein the pressure difference between the fuel pressures within the chambers results
Data Source
Figure 1a~1c
Figure 2A~2B
Figure 3a~3c
AI summary
The invention relates to a valve unit (100) with a valve chamber (10), in particular a cylindrical one, which is arranged in a housing (101), and which is divided by means of an adjusting body (11) arranged in the valve chamber (10) in a fluid-tight manner into two fluid-tightly separated chambers through which fuel can flow or through which fuel flows, a first chamber (10a) and a second chamber (10b), wherein - the valve chamber (10) has a first inlet (8) for supplying a first fuel portion, in particular main fuel, and a second inlet (9) for supplying a second fuel portion, in particular pilot fuel, - the valve chamber (10) has a first outlet (5), in particular for supplying fuel to an engine main stage, and a second outlet (6), in particular for supplying fuel to an engine pilot stage, - the valve unit (100) has a valve chamber (100) arranged in one of the chambers (10a, 10b), in particular in the second chamber (10b),arranged and coupled to the actuating body (10) in a force-transmitting manner, elastic return element (12), in particular a spring arrangement, and - the valve unit (100) is designed such that an actuating force for positioning the actuating body (11) within the valve chamber (10) is generated by the interaction of a return force of the return element (12) with a pressure difference existing between the chambers (10a, 10b), which results between the fuel pressures within the chambers (10a, 10b), whereby the actuating body (11) can be adjusted into a closed position blocking the second outlet (6). For reliable operation, it is provided that the second chamber (106) is provided with a further inlet (23) for supplying a further fuel portion and a further outlet (24) via which fuel can be discharged from the second chamber (106) and which remains open,when the actuator (11) is in the closed position of the second outlet (6) (Fig. 3A).