Variable Displacement Fuel Pump Feedback Control for Accurate Metering
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Solution Overview
Problem
Existing variable displacement pumps (VDPs) face challenges in reducing fuel system weight and heat rejection, improving reliability, and increasing fuel flow accuracy for aircraft applications, while conventional control systems are inadequate.
Innovation Solution
A system incorporating a variable displacement pump with an electromechanical actuator, flow sensing valve, and minimum pressure shutoff valve, controlled by a controller that uses sensors for feedback to manage flow and pressure, enabling direct electrical actuation and precise fuel delivery to aircraft engines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional control systems are used for variable displacement pumps, then system simplicity is maintained, but fuel flow accuracy and metering capability are insufficient
Solution Approach 1:
The patent implements a feedback control system where a sensor detects actual fuel flow or pressure and feeds this information back to the controller. The controller compares the feedback signal with the desired setpoint and adjusts the electromechanical actuator accordingly to maintain accurate fuel flow delivery, thereby resolving the contradiction between improved measurement precision and increased device complexity.
Solution Approach 2:
The patent replaces conventional mechanical control systems with an electromechanical actuator controlled by electronic signals from a controller. This substitution enables more precise control and measurement capabilities while maintaining reasonable system complexity through electronic rather than mechanical means.
2Device complexity
If valve count is reduced in the pump system, then device complexity and weight are decreased, but flow control precision and reliability may be compromised
Solution Approach 1:
The patent designs valves and control components to perform multiple functions. For example, the electromechanical actuator serves both as a control mechanism and a position indicator, and the sensor system provides both feedback for control and monitoring functions. This multi-functionality reduces the number of separate components while maintaining or enhancing system reliability.
Solution Approach 2:
The control system is designed to be self-regulating through feedback control, where the system automatically adjusts its own operation without requiring additional manual intervention or complex external control mechanisms. This self-service capability maintains reliability while reducing the number of control valves and components needed.
3Weight of moving object
If weight is reduced in the fuel system, then aircraft fuel capacity and heat rejection capability are improved, but component durability and reliability may be affected
Solution Approach 1:
The patent replaces heavy mechanical control systems with lighter electromechanical actuators and electronic control components. This substitution significantly reduces fuel system weight while maintaining or improving reliability through electronic control precision and the ability to implement sophisticated control algorithms that enhance component performance and durability.
Solution Approach 2:
The patent changes the operating parameters and control methods of pump components to optimize performance at reduced weights. By using variable displacement mechanisms controlled by electronic actuators, the system achieves the required fuel flow accuracy and reliability without the weight penalty of traditional mechanical systems.
4Temperature
If heat rejection capability is increased, then aircraft fuel capacity is improved, but pump system thermal management complexity increases
Solution Approach 1:
The patent designs the pump system with inherent thermal management capabilities where the fuel itself serves as the cooling medium. The variable displacement pump and associated components are configured to utilize fuel flow for heat rejection without requiring separate thermal management systems, thereby increasing heat rejection capability while avoiding additional thermal management complexity.
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 system reduces valve count, enhances fuel flow accuracy, and provides faster metering capabilities, thereby improving the reliability and efficiency of fuel delivery to gas turbine engines.
Implementation Method 1
An electromechanical actuator (EMA) is operatively connected to actuate the variable displacement mechanism
Implementation Method 2
A biasing member biases the valve member in a first direction
Implementation Method 3
Pressure of flow through the FSV from the FSV inlet to the FSV outlet biases the valve member in a second direction opposite the first direction
Implementation Method 4
A solenoid valve (SOL) can be connected in fluid communication with the outlet line and with the MPSOV control line for actuating the MPSOV between first and second states
Data Source
Figure 1
Figure 2
AI summary
A system includes a variable displacement pump (VDP (102)) in fluid communication with an inlet line (104) and with an outlet line (106). The VDP (102) includes a variable displacement mechanism (108) configured to vary pressure to the outlet line (106). An electromechanical actuator (EMA (110)) is operatively connected to actuate the variable displacement mechanism (108). A flow sensing valve (FSV (112)) connected in the outlet line (106). The FSV (112) includes a sensor configured to generate sensor data indicative of flow out of the outlet line (106). A controller (118) is operatively connected to the EMA (110) to control the variable displacement mechanism (108) based on the sensor data to support flow demands from one or more downstream systems.