Multi-Step Fuel Pressurizing Valve for Low-Speed Actuation
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Solution Overview
Problem
Conventional fuel systems for turbine engines require high minimum pressure differentials to regulate actuator flow, making ground maintenance and low-speed actuation difficult due to large pump sizes and sensitivity to pressure variations.
Innovation Solution
The fuel system eliminates the inlet pressurizing valve, providing high pressure fuel directly to the bypass valve, allowing actuator control at a lower pressure differential (as low as 90 psid) and pressurizing in steps for low-speed movement, with a flow sense valve controlling downstream actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an inlet pressurizing valve is used to regulate fuel flow to actuators, then the system can control actuator flow, but a high minimum pressure differential (350 psid) is required making ground maintenance and low-speed actuation difficult
Solution Approach 1:
The fuel system is divided into multiple pressurization stages: a low-pressure stage (90 psid) for ground maintenance and low-speed actuation, and a high-pressure stage for high-speed engine operation. This segmentation allows the system to operate at different pressure levels depending on the operational phase, eliminating the need for continuously high pressure differential.
Solution Approach 2:
The system dynamically switches between different pressurization modes based on operational requirements. The multi-step pressurizing valve system adjusts pressure differential in real-time, providing low pressure (90 psid) when actuators need to move at low speeds or during ground maintenance, and high pressure during high-speed engine operation.
2Productivity
If a high pressure differential (350 psid) is maintained to enable actuator flow, then actuator control is achieved, but pump size must be relatively large due to leakage being proportional to the square root of pressure differential
Solution Approach 1:
The system dynamically adjusts pressure differential based on operational phase. During ground maintenance and low-speed actuation, pressure is reduced to 90 psid, significantly reducing leakage and allowing for a smaller pump. During high-speed engine operation, pressure increases to maintain required actuator flow control.
Solution Approach 2:
The system changes the pressure differential parameter from a fixed high value (350 psid) to a variable value that can be as low as 90 psid during low-speed operation. This parameter change directly reduces leakage (proportional to square root of pressure differential) and allows for smaller pump sizing.
3Productivity
If pump speed is increased to at least 15% to provide high enough pressure for IPV valve member positioning, then fuel flow to regulating valve is enabled, but actuator movement for ground maintenance functions is not allowed
Solution Approach 1:
The system uses dynamic pressure control with a multi-step pressurizing valve that can operate at reduced pump speeds (corresponding to 90 psid differential) while still enabling sufficient fuel flow to the regulating valve for ground maintenance functions. This eliminates the requirement for minimum 15% pump speed.
4Stress or pressure
If the inlet pressurizing valve is eliminated and high pressure fuel is provided directly to the bypass valve, then the system can operate at lower pressure differential (90 psid), but system complexity must be managed
Solution Approach 1:
The inlet pressurizing valve and bypass valve functions are merged into a single multi-step pressurizing valve system. This integrated valve performs both pressurization and bypass functions, reducing the total number of separate components while achieving the desired low pressure differential operation (90 psid).
Data Source
AI summary
Embodiments of a fuel system are disclosed. The fuel system includes a bypass valve (BPV), a fuel metering valve (FMV), a flow sense valve (FSV), and an actuator regulating valve (ARV). The BPV includes a BPV valve member that regulates fuel flow from a BPV inlet to a BPV outlet. The position of the BPV valve member is controlled by pressures at an inlet and an outlet of the FMV. The FSV includes an FSV valve member that regulates fuel flow from an FSV inlet to an FSV outlet. The ARV includes an ARV inlet that is in fluid communication with the FSV outlet, and fuel flow through an ARV outlet regulates downstream actuators. The position of the FSV valve member to produce fuel flow through the FSV outlet to the ARV inlet is controlled at least in part by a pressure at the BPV outlet.