Integrated Oil Pump Heating for Aircraft Lubrication Circuits
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Solution Overview
Problem
Aircraft turbomachines face challenges with bulky, heavy, and expensive hydraulic systems due to separate circuits for oil heating and cooling, which are redundant and inefficient, particularly in managing oil temperature for fuel cells and turbojet engines, leading to mechanical stress and weight issues.
Innovation Solution
Integration of an electric oil circulation pump with a heating element into the hydraulic lubrication circuit, allowing for temperature regulation and sharing of oil between the turbojet and fuel cell circuits, minimizing system bulk and weight by incorporating pumping, heat exchange, and pressure regulation functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate hydraulic circuits are used for turbojet lubrication and fuel cell heating, then each circuit can be optimized for its specific function, but the overall system becomes bulky, heavy, and expensive with redundant components
Solution Approach 1:
The patent combines the turbojet lubrication circuit and fuel cell heating circuit into a single integrated hydraulic system. The same oil circuit serves dual purposes: lubricating turbojet components and heating fuel cell oil. This merging eliminates redundant components, reduces overall system weight, and decreases component count while maintaining functional optimization for both applications
Solution Approach 2:
The hydraulic system is designed with multi-functionality, where a single oil circuit performs multiple functions simultaneously. The oil serves as both lubricant for the turbojet and heat transfer medium for the fuel cell. This universal approach allows one system to fulfill roles that previously required separate dedicated circuits
2Reliability
If oil heating systems are added to prevent oil solidification at low temperatures, then the fuel cell can start safely, but the system becomes heavier and more complex
Solution Approach 1:
The heating function is merged into the existing hydraulic system rather than being added as a separate dedicated system. The same oil circuit that provides lubrication also serves as the heat transfer medium for preventing oil solidification. Heating elements are integrated into the pump or heat exchanger components that already exist in the system
Solution Approach 2:
The hydraulic system serves itself by using the oil circulation already required for lubrication to also perform the heating function. The pump that circulates oil for lubrication simultaneously moves oil through heating pathways, eliminating the need for separate pumping systems dedicated solely to heating
3Reliability
If oversized pumps are used to force circulation of solidified oil, then the fuel cell can start, but the pump weight increases and mechanical stress on hydraulic components increases
Solution Approach 1:
Heating elements are activated before the pump starts circulating oil to prevent solidification. This preliminary heating action ensures the oil remains in a liquid, pumpable state before circulation begins, eliminating the need for oversized pumps designed to handle solidified oil
Solution Approach 2:
The system provides protective heating ahead of time to cushion against the harmful effect of oil solidification. By maintaining oil temperature above freezing point through integrated heating elements, the system prevents the adverse condition that would require oversized pumps and creates excessive mechanical stress
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 enables efficient temperature management of oil, preventing freezing and overheating, reducing the size and weight of the hydraulic assembly, and eliminating the need for dedicated heating systems, while maintaining optimal operation of both the turbojet and fuel cell.
Implementation Method 1
an electric oil circulation pump incorporating a heating element for heating the oil
Implementation Method 2
the heating element is an electrical resistor embedded in the pump body to be in direct contact with the oil
Implementation Method 3
The turbojet lubrication circuit includes a section that forms a heat exchanger with the turbojet bleed air to heat the oil
Implementation Method 4
The turbojet lubrication circuit also includes a section that forms a heat exchanger with ambient air or the turbojet bypass air to cool the oil
Implementation Method 5
At least one of the circuits includes a device for inductively heating a cavity containing oil
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a system for an aircraft, comprising: a turbojet engine (2) equipped with a hydraulic lubrication circuit (30); and/or a fuel cell (28) equipped with a hydraulic circuit (40) for reaching and maintaining the operating temperature. The system of the invention is characterised in that at least one of the circuits (30, 40) comprises an electric circulation pump (50) incorporating a heating element for heating the oil. The heating element can in particular be a heating module or the DC-powered coil of the pump, in thermal contact with the oil. The invention also relates to an air/oil heat exchanger for such a system. The exchanger comprises a matrix produced by means of additive manufacturing.