Fuel Pump Epicyclic Drive With Reversible Power Transfer
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Solution Overview
Problem
The existing fuel supply system in turbomachines delivers excess fuel flow rate, leading to inefficient power collection and increased thermal dissipation, which negatively impacts performance, size, and mass, particularly due to the need for heat exchangers to dissipate excess mechanical power in the recirculation loop.
Innovation Solution
A transmission device with an epicyclic gear reducer and reversible electrical power transfer between motors adjusts the pump speed to match fuel flow requirements, minimizing power collection and potentially eliminating the recirculation loop by optimizing power transfer and reducing the size of the fuel circuit components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump displacement is dimensioned to ensure enough flow rate at low speed ignition, then the fuel flow rate requirement is met at ignition, but the pump delivers excess fuel flow rate during cruise flight, leading to power collection inefficiency and thermal dissipation
Solution Approach 1:
The patent applies a variable displacement pump mechanism that allows the pump displacement to be dynamically adjusted based on operating conditions. The pump displacement can vary between a first value at low speed ignition to ensure sufficient fuel flow, and a second lower value during cruise flight to match the reduced fuel requirement, thereby eliminating excess fuel delivery and improving power collection efficiency
Solution Approach 2:
The invention changes the physical parameter of pump displacement from a fixed value to a variable parameter. By adjusting the displacement parameter according to the operating regime (ignition vs. cruise flight), the system optimizes fuel flow delivery to match actual requirements, preventing energy loss from recirculating excess fuel
2Reliability
If the pump displacement is dimensioned for high speed take-off, then the fuel flow rate requirement is met at take-off, but the pump delivers insufficient fuel flow rate at low speed ignition
Solution Approach 1:
The variable displacement mechanism enables the pump to adapt its displacement to different speed regimes. At high speed take-off, the displacement is set to a value that delivers sufficient fuel flow, while at low speed ignition, the displacement is increased to compensate for the lower rotational speed, ensuring adequate fuel delivery across all operating conditions
Solution Approach 2:
The system adjusts the displacement parameter inversely to the rotational speed parameter. When speed decreases at ignition, displacement increases to maintain fuel flow; when speed increases at take-off, displacement decreases to prevent excess fuel delivery
3Reliability
If a recirculation loop is used to return excess fuel to the pump, then the fuel flow rate is adjusted to match requirements, but the excess mechanical power is transformed into high thermal power that must be evacuated, increasing system size and mass
Solution Approach 1:
The invention extracts and eliminates the recirculation loop from the fuel system by using variable displacement control. Instead of recirculating excess fuel through a complex loop with heat exchangers, the system adjusts pump displacement to prevent excess fuel generation in the first place, removing the need for thermal management infrastructure and reducing system mass
Solution Approach 2:
Rather than managing the harmful effect of excess fuel through recirculation and heat exchangers, the invention converts the problem into a benefit by using the variable displacement mechanism to precisely match fuel delivery to demand, turning what would be wasted energy into useful work without thermal dissipation
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 ensures the fuel pump delivers the correct fuel flow rate across operating points, reduces power collection inefficiencies, and simplifies the fuel system by minimizing the size and mass of the fuel circuit, eliminating the need for external power and reducing thermal dissipation.
Implementation Method 1
an epicyclic gear reducer comprising three elements, a central sun gear, an outer ring gear and a planet carrier, the planets of which engage with the sun gear and the ring gear
Implementation Method 2
first electrical means arranged so as to rotatably drive the third of said elements of the reducer... and second electrical means coupled to the first or the second of said elements of the reducer, the first and second electrical means being arranged so as to transfer electrical power reversibly from one to the other
Data Source
AI summary
A transmission device drives a fuel pump for a turbomachine using a drive shaft of said turbomachine. The transmission includes a planet reduction gearing with three elements: a central planet gear, an outer ring gear and a planet carrier. A first of the three elements connects to the drive shaft and a second of the three elements couples to a shaft of the pump. The three elements can be rotated about a shaft of the reduction gearing. First electrical means rotatably drive the third element to modify a rotational speed ratio between the first and second elements. Second electrical means are coupled to the first or the second element. The first and second electrical means are arranged to transfer electrical power reversibly from one to the other.