Variable Speed Fuel Pump Motor Control for Gas Turbine
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Solution Overview
Problem
Gas turbine engine fuel systems are inefficient due to oversized fuel pumps that result in excess flow and heating during operational speed, leading to increased cost, size, and weight, as well as unwanted fuel recirculation.
Innovation Solution
A fuel control system utilizing a variable speed pump motor controlled by a closed-loop electronic feedback system that adjusts fuel pump speed to match the engine's desired flow schedule, eliminating the need for oversized pumps and reducing recirculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a fuel pump is sized to provide sufficient fuel flow during engine start-up (5-15% of operational speed), then the pump can deliver required fuel quantity during light-off window, but the pump becomes oversized at operational speed, resulting in three or four times larger size than needed and excess fuel flow
Solution Approach 1:
The patent applies a variable speed drive system that dynamically adjusts the fuel pump's rotational speed based on real-time engine conditions. The controller receives engine operating parameters and modulates the pump motor speed to match actual fuel demand, allowing a smaller pump to deliver variable flow rates from start-up conditions through operational phases without being oversized.
Solution Approach 2:
The system changes the operational parameters of the fuel pump by varying its rotational speed rather than maintaining constant speed. The variable speed drive enables the pump to operate at different speeds corresponding to different engine phases (start-up, acceleration, steady-state), allowing optimal fuel delivery across all conditions with a appropriately sized pump.
2Productivity
If the fuel pump operates at high speed to deliver sufficient fuel during start-up, then fuel flow requirement is met, but the pump develops excess flow at operational speed causing fuel recirculation through the relief valve and unwanted heating of the fuel
Solution Approach 1:
The variable speed drive dynamically adjusts pump speed to match actual fuel demand, preventing excess flow generation. By reducing pump speed when engine fuel requirements decrease, the system eliminates the need for fuel recirculation through relief valves, thereby preventing unwanted fuel heating while maintaining adequate delivery rates during all operational phases.
Solution Approach 2:
The control system implements feedback by monitoring engine operating conditions and adjusting pump speed accordingly. The controller receives real-time data about engine load and speed, then modulates the variable speed drive to maintain optimal fuel flow, preventing both excess flow and the resulting fuel heating that would occur with fixed-speed operation.
3Power
If a gearbox driven fuel pump is used to couple the engine to the pump, then the pump receives mechanical power, but the system contributes to excess cost, size and weight of the fuel system
Solution Approach 1:
The patent replaces the mechanical gearbox transmission system with an electrical variable speed drive system. Instead of using mechanical gears to reduce engine speed and drive the pump, the system uses an electric motor with electronic speed control, eliminating the gearbox and its associated weight, complexity, and cost while providing more precise speed control capability.
4Ease of operation
If a servo-control valve is used to control fuel flow, then fuel flow can be regulated, but the system contributes to device complexity and does not eliminate the need for oversized pump
Solution Approach 1:
The system replaces mechanical flow control valves with electronic speed control of the pump motor. Instead of using servo-control valves to restrict flow from an oversized pump, the invention uses electronic modulation of motor speed to precisely control fuel delivery, simplifying the overall system by eliminating complex valve mechanisms while maintaining accurate flow regulation.
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 ensures precise fuel delivery, minimizing excess flow and heating, thereby reducing the size, weight, and cost of the fuel system while maintaining efficient operation.
Implementation Method 1
a motor controller that powers the pump motor, compares the speed of the pump motor to a motor speed command signal that represents a desired fuel flow for the pump, senses any variation of the speed of the motor from the motor speed command signal and uses the resulting difference to modulate the power that it sends to the pump motor
Data Source
AI summary
A fuel control system uses a fuel pump powered by a variable speed pump motor controlled by a closed loop electronic feedback system that tracks motor speed and corrects fuel pump motor speed so that the fuel pump delivers flow according to a desired flow schedule based on the pressure feedback from the manifold.