Aircraft Fuel Pump Actuation With Dahlander Speed Matching
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Solution Overview
Problem
Existing fuel pump actuation devices for aircraft engines are inefficient as they require oversized pumps to meet fuel flow demands across varying engine speeds, leading to excess fuel flow and the need for recirculation, which results in heat dissipation and negatively impacts the oil circuit's exchangers.
Innovation Solution
An actuation device featuring an asynchronous rotating electric driving machine with Dahlander coupling and an electrical connection member that adjusts the connection of windings in series or parallel based on engine speed, allowing for optimized pump sizing and reduced fuel recirculation by matching fuel flow to engine requirements across different operating points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump is sized to meet the fuel flow demand at low engine speeds, then the fuel flow requirement is satisfied across all operating points, but the pump delivers excess fuel flow at high engine speeds requiring recirculation
Solution Approach 1:
The patent applies Dahlander coupling to the electrical connection member, enabling dynamic reconfiguration of motor winding connections between series and parallel arrangements. This allows the motor's speed-torque characteristics to change dynamically with engine operating conditions, matching pump output to actual fuel demand across the full engine speed range without excessive recirculation
Solution Approach 2:
The electrical connection member changes the electrical parameters of the motor by reconfiguring winding connections. At low engine speeds, windings are connected in series to provide higher torque at lower speeds; at high engine speeds, windings are connected in parallel to allow higher rotational speeds, thereby adjusting the pump's fuel delivery characteristic to match engine requirements
2Reliability
If a fuel recirculation device is installed to handle excess fuel flow, then the fuel flow mismatch is managed, but mechanical power is drawn from the gearbox and dissipated as heat
Solution Approach 1:
The patent eliminates the harmful recirculation loop by preventing the creation of excess fuel flow in the first place. Through Dahlander coupling, the motor-pump system adapts its characteristics to match engine demand, converting what would have been a harmful waste problem into a benefit of precise flow matching without requiring recirculation or heat dissipation
3Quantity of substance
If the pump displacement is increased to satisfy fuel flow at the lowest operating point, then fuel supply is adequate at all speeds, but the gap between required and supplied fuel flow increases at higher speeds
Solution Approach 1:
Instead of using a fixed large-displacement pump, the system employs a motor with variable characteristics through Dahlander coupling. The motor dynamically adjusts its speed-torque curve to match the engine's fuel demand characteristics, allowing a smaller pump to deliver the appropriate fuel flow at each operating point without the need for oversized capacity
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
This solution reduces the difference between required and supplied fuel flow, minimizing the need for fuel recirculation and associated heat dissipation, thereby improving the efficiency and performance of the fuel pumping system.
Implementation Method 1
an asynchronous rotating electrical driving machine with Dahlander coupling comprising a first rotor, intended to be mechanically coupled to each pump for its actuation
Implementation Method 2
a rotating electrical generating machine comprising a second rotor, intended to be mechanically coupled to a shaft of the motor forming a drive shaft
Data Source
Figure 1~3
Figure 2
AI summary
The invention relates to an actuating device (12) of a fuel pump (20) for an aircraft engine (18), the actuating device (12) comprising a motor (24), a generator (26) and an electrical connection member (27), the motor (24) being an asynchronous machine with Dahlander coupling comprising a first rotor (32) coupled to the pump (20) for its actuation, and a first stator (34) comprising at least one input phase (36), each input phase comprising two windings (39), the generator (26) comprising a second rotor (32) mechanically coupled to a shaft (37) of the engine (18), and a second stator (40) comprising at least one output phase (42), the electrical connection member (27) being configured so as to connect each output phase (42) to an input phase (36), and to connect the windings (39) of each input phase (36) in series or in parallel according to an engine speed (18).