Hydraulic system for lubrication of turbojet engine
阅读说明:本技术 用于涡轮喷气发动机的润滑的液压系统 (Hydraulic system for lubrication of turbojet engine ) 是由 A.科尼特 N.雷马克斯 于 2019-04-18 设计创作,主要内容包括:本发明涉及一种用于飞机的系统,包括:涡轮喷气发动机(2),其配备有液压润滑回路(30);和/或燃料电池(28),其配备有用于达到和维持工作温度的液压回路(40)。本发明的系统的特征在于,至少一个回路(30,40)包括电动循环泵(50),其包括用于加热油的加热元件。加热元件可以特别是泵的热接触油的加热模块或DC供电线圈。本发明还涉及用于这样的系统的空气/油热交换器。该交换器包括通过增材制造生产的基体。(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 an operating temperature. The system of the invention is characterized in that at least one circuit (30, 40) comprises an electric circulation pump (50) comprising a heating element for heating the oil. The heating element may in particular be a heating module of a pump in thermal contact with oil or a DC power supply coil. The invention also relates to an air/oil heat exchanger for such a system. The exchanger includes a substrate produced by additive manufacturing.)
1. A system for an aircraft, the system comprising:
a turbojet engine (2) having a hydraulic lubrication circuit (30); and/or
A fuel cell (28) having a hydraulic circuit (40) for setting and maintaining an operating temperature of the fuel cell;
characterized in that at least one of said circuits (30, 40) comprises an electric pump (50, 150, 250) for conveying oil, said pump having an integrated heating element (51, 56, 57) for heating the oil.
2. The system of claim 1, comprising a turbojet engine (2) and a fuel cell (28), the temperature setting and maintenance circuits (40) of the lubrication circuit (30) and of the fuel cell (28) of the turbojet engine (2) forming a single common circuit (30, 40).
3. System according to claim 1 or 2, characterized in that the electric pump (50, 150, 250) comprises an electric motor (55, 56) provided with a coil (56), and that the coil (56) is supplied with a direct current to heat the coil, the direct current preferably exceeding the rated operating value of the coil.
4. A system according to any one of claims 1 to 3, characterized in that the pump (50, 150, 250) comprises a body (51) and the heating element is an electric resistor (57) embedded in the body (51) of the pump (50, 150, 250) intended to be in direct contact with the oil.
5. System according to any one of claims 1 to 4, characterized in that the pump comprises a body (51) and the heating element is the body (51) of the pump, which is made of a heat conducting material comprising at least one of aluminium, silver, copper, zinc.
6. System according to any one of claims 1 to 5, characterized in that said circuit (30, 40) comprises a pump (50, 150, 250) and also a tank (60) for the oil, the pump (150, 250) being integral with or in direct contact with the tank so that its heating element (51, 56, 57) heats the oil in the tank (60).
7. The system of claim 6, wherein the circuit comprises a lubrication module (350) thermally positioned in contact with the tank (60).
8. System according to claim 6 or 7, characterized in that the tank (60), the pump (50, 150, 250) and the heating element (51, 56, 57) and possibly the lubricating module (350) constitute a modular assembly wrapped in a casing.
9. The system of claim 8, wherein the outer shell is shaped for introduction into a cavity of an aircraft wing.
10. System according to any one of claims 1 to 8, characterized in that at least one of said circuits (30, 40) comprises heating means realized by induction of a cavity containing oil.
11. System according to claims 6 and 10, characterized in that the induction heating means are coils close to and/or surrounding the tank (60), the walls of which are ferromagnetic.
12. A system according to any one of claims 1 to 11, characterized in that the hydraulic lubrication circuit (30) of the turbojet engine (2) comprises a portion forming an exchanger (34) for heat exchange with the air at the exhaust of the turbojet engine for heating the engine oil.
13. A system according to any one of claims 1 to 12, characterized in that the lubricating circuit (30) of the turbojet engine (2) comprises a portion forming an exchanger (34) for heat exchange with ambient air or with turbojet engine bypass air, for cooling said oil.
14. System according to claim 12 or 13, characterized in that said circuit (30, 40) comprises valves and pumps (50, 150, 250) and a system for actuating said valves and pumps to circulate oil in one and/or the other exchanger (34) according to the measured and target oil temperatures.
15. Oil management method in an aircraft system, characterized in that the system is a system according to one of claims 1 to 14 and that the temperature of the oil is measured and the oil is heated if the temperature of the oil is below a first threshold temperature, in particular 20 ℃.
16. Method according to claim 15, characterized in that the energy demand of the aircraft or turbojet is evaluated and the oil is heated only if the energy demand of the aircraft necessitates that the fuel cell fuel (28) be put into operation.
17. Method according to claim 15 or 16, characterized in that the oil is cooled if the temperature of the oil is above a second threshold temperature, in particular 150 ℃.
18. System according to any of claims 15-17, characterized in that the electric pump (50, 150, 250) comprises an electric motor (55, 56) provided with a coil (56), and that the coil (56) is supplied with a direct current to heat the coil, the direct current preferably exceeding the rated operating value of the coil.
19. Method according to claim 18, characterized in that when the oil is below the first threshold value, the coil (56) is supplied with an electric current which is maintained between 110% and 150% of its nominal value.
20. The method of any one of claims 15 to 19, wherein the system includes a power supply circuit for the pump, such that the electric pump (50, 150, 250) is powered only by the fuel cell (28) when the fuel cell (28) is operating.
21. An air/oil heat exchanger for a turbojet engine (2) comprising a base body (130, 230) and a heating element (162), the base body (130, 230) comprising:
a channel (136, 236) for air flow;
a network (134, 244) in which the oil flows and supports at least two sequences of cooling fins (138, 140, 238, 240) along the air flow, the base further comprising a housing (160, 260) for receiving said heating element (162).
22. Exchanger according to claim 21, wherein the fins (138, 140, 238, 240) extend along main directions inclined with respect to each other.
23. An exchanger according to claim 21 or 22, characterised in that the housing (160, 260) comprises a wall which cooperates with the oil in the network (134, 244).
24. The exchanger according to any of claims 21 to 23, wherein the shell (160) is a straight tube or a zigzag tube.
25. Exchanger according to any one of claims 21 to 24, wherein the heating elements (162) are heating rods, resistors and/or heating films.
26. The exchanger of any one of claims 21 to 25, wherein the substrate is manufactured by an additive manufacturing method.
27. A turbomachine (2), in particular a turbojet, comprising a heat exchanger (34) with a base body (130; 230), a bearing (26) and a gearbox (22) driving a fan (16), characterized in that the exchanger (34) is according to any one of claims 21 to 26.
28. System according to any one of claims 12 to 14, wherein the exchanger (34) is according to any one of claims 21 to 26.
Technical Field
The present invention relates to the field of lubrication of turbine engines. More particularly, the present invention relates to the management of oil in aircraft systems.
Background
Some aircraft may include batteries to power certain equipment or to conserve fuel by supplementing the power requirements of the turbojet engine. The fuel cells, which are usually integrated into the fuselage, have their own oil circuit to hold the electrode stack. The oil maintains the fuel cell at an optimum operating temperature, for example, between 20 ℃ and 150 ℃. However, at too low a temperature, the oil freezes and condenses, and the pump is therefore unable to deliver oil, preventing the fuel cell from starting safely. Therefore, some pumps are oversized to force the oil to pump even when frozen. This means that the pump is heavier and the mechanical stresses applied to the components of the hydraulic circuit (pipes, valves, etc.) are greater. Another solution is to provide a dedicated oil heating system for the fuel cell.
On the other hand, certain oils operating at high temperatures (above 200 ℃) give the heat exchanger good performance, so that smaller heat exchangers can be used. These oils contain additives that make them chemically aggressive to the hydraulic system. Therefore, it is difficult to balance the weight of the heating system or the oversized pump by increasing the weight of the heat exchanger.
For turbojet engines of aircraft, it also comprises hydraulic circuits, in particular for lubricating the moving parts to limit wear thereof. In some cases it is used to cool certain mechanical parts, which results in a temperature rise above 200 ℃. Furthermore, when the oil is used to de-ice the nacelle and compressor inlet nozzle, it is exposed to temperatures below-40 ℃, which requires a wide operating temperature range for the oil. Incidentally, this oil can also be used to actuate the cylinder when compressed. Finally, the oil helps to monitor wear, as the oil carries particles released by the moving parts, which can be absorbed by the magnetic element.
Thus, in an aircraft equipped with a turbojet and with a fuel cell, there are two separate hydraulic circuits, each of which is particularly bulky. On the one hand heating oil and on the other hand cooling oil is required. This involves many parts, is sometimes redundant, and results in a hydraulic assembly that is bulky, expensive, and heavy.
Disclosure of Invention
Technical problem
It is an object of the present invention to overcome at least one of the disadvantages of the prior art. More specifically, the invention aims to optimize the lubrication of the aircraft and in particular to solve the problems caused by the oil freezing at low temperatures. The object of the present invention is also to provide a compact solution which is simple, light, economical, reliable, easy to produce and easy to maintain.
Technical scheme
The invention relates to a system for an aircraft, comprising: a turbojet engine provided with a hydraulic lubrication circuit, and/or a fuel cell provided with a hydraulic circuit for setting and maintaining an operating temperature; characterized in that at least one circuit comprises an electric circulation pump with a heating element for heating the oil.
Such a system makes it possible to raise the oil temperature to supply it to the fuel cell without freezing the oil.
The hydraulic lubrication circuit of a turbojet engine lubricates and cools mechanical parts, such as bearings, gearboxes or electrical equipment. The fuel cell is generally designed to be located in the fuselage of the aircraft, thus far from the turbojet engine, and comprises a hydraulic circuit for setting and maintaining its operating temperature.
The heating element of the electric pump may be an element that actively heats the pump, an element that heats due to the proximity of the pump to a thermal element (heat conducting wall), or an element that increases in temperature due to an external energy source (resistor, coil).
The solution of the invention is therefore the integration of several functions (pumping, heat exchange, pressure regulation) to minimize the weight and volume of the whole hydraulic system.
According to a preferred embodiment of the invention, the system may comprise one or more of the following features, taken separately or according to all possible technical combinations:
the system comprises a turbojet and a fuel cell, the lubrication circuit of the turbojet and the circuit for setting and maintaining the temperature of the fuel cell forming a single common oil circuit. Thus, the two circuits may share at least one common tank, and the oil cooled or heated in the turbojet may be circulated in contact with the fuel cell to cool or reheat the temperature;
-the electric pump comprises an electric motor provided with a coil and supplies a direct current to the coil to heat it, the direct current preferably being higher than the nominal operating value of the coil;
the pump comprises a body and the heating element is an electrical resistor embedded in the pump body to be in direct contact with the oil;
-the pump comprises a body and the heating element is the body of the pump made of a heat conductive material and containing at least one of: aluminum, silver, copper, zinc. The body may be composed of an alloy of one or more of these elements. Thus, since the pump is located near the heat source, the oil can be heated by simple conduction through the body of the pump. The heat source may be, for example, an electrical module of the turbojet engine or a mechanical component thereof.
The circuit containing the pump also comprises a tank for the oil, the pump being integrated in the tank or directly in contact with the tank so that its heating element heats the oil in the tank. The tank may be provided with a deaerator to remove air from the oil;
-said circuit comprises a lubricating module in thermal contact with the tank. The lubrication module may include pumps, temperature, pressure or flow sensors, a housing recovery function and associated electronic controls. By "thermal contact" is meant that the lubricating module can be attached to the tank to transfer energy thereto by heat transfer.
The tank, the pump and the heating element and possibly the lubricating module constitute a modular assembly wrapped in a casing. It is therefore possible to completely enclose the tank, the pump and the heating element to have a modular form in which only the inlet and the oil outlet are accessible when assembling the turbojet engine;
the shape of the outer skin is designed to be introduced into a cavity of an aircraft wing. Alternatively, the outer casing of the module may be curved or may form an annular portion to be introduced into the turbojet engine.
At least one of said circuits comprises heating means for heating the cavity containing the oil by induction. The induction heating means may be a coil of a tank adjacent to and/or around the wall of which it is ferromagnetic;
the turbojet lubrication circuit comprises a portion forming an exchanger in heat exchange with the air of the turbojet exhaust gases to heat the oil. This hot air, which can be discharged at the compressor outlet and upstream of the combustion chamber, can indeed heat the oil;
the turbojet lubrication circuit comprises a portion forming an exchanger in heat exchange with ambient air or bypass air of the turbojet to cool the oil;
the circuit comprises valves and pumps and control means for controlling the valves and pumps to circulate the oil in one or the other exchanger, according to the measured oil temperature and the target oil temperature. If the temperature exceeds the optimum range, the oil will be conducted in the bypass cooling exchanger. If the temperature is below the target range, the oil will be conducted in the exhaust air exchanger.
The invention also relates to a method for managing oil in a system as described above.
According to the method, the oil temperature is measured and heated if the temperature of the oil is below a first threshold temperature, in particular 20 ℃.
According to a preferred embodiment of the method, the energy requirement of the aircraft or turbojet is evaluated and the oil is heated only if the energy requirement of the aircraft is such that the fuel cell has to be operated.
According to a preferred embodiment, the oil is cooled if the temperature of the oil is above a second threshold temperature, in particular 150 ℃.
According to a preferred embodiment, the electric pump comprises an electric motor provided with coils, and the coils are supplied with a direct current in order to heat them, the direct current preferably being higher than the rated operating value of the coils.
In a preferred embodiment, the coil is supplied with a direct current that is maintained between 110% and 150% of its nominal value as long as the oil is below the first threshold value. This range of values is used to generate heat without damaging the pump.
According to a preferred embodiment, the system comprises a circuit for powering the pump, such that the electric pump is powered only by the fuel cell when the fuel cell is running. Such circuitry may include a switch that is controlled to select the power supply for the pump. When the fuel cell is switched off, it is naturally necessary to supply the electric pump with power by other auxiliary means.
The problems with freezing and condensing cold oil in the hydraulic circuit can also be solved by a turbine air/oil heat exchanger comprising a base body and a heating element, the base body comprising: a passage for an air flow; a network in which the oil circulates, the network supporting at least two successive cooling fins according to the air flow; the base body further comprises a housing for accommodating said heating element.
In fact, the fact of introducing the heating element directly into the matrix of the heat exchanger is a compact and inexpensive solution, ensuring the correct functioning of the hydraulic circuit when the oil is cold.
According to a preferred embodiment of the invention, the system may comprise one or more of the following features, taken separately or according to all possible technical combinations:
the fins extend in respective main directions inclined with respect to each other;
-the housing comprises a wall cooperating with the oil in the network;
-the shell is straight tubular or serrated;
the heating element is a heating rod, a resistor and/or a heating film;
the invention also relates to a turbomachine, in particular a turbojet, comprising a heat exchanger with a base body, bearings and a gearbox for driving a fan, characterized in that the exchanger is in accordance with one of the above-mentioned embodiments.
According to a particular embodiment, the matrix may comprise one or more of the following features, taken individually or according to all possible technical combinations:
-the main directions of successive fins are inclined at least 10 ° or at least 45 ° with respect to each other;
-air flows through the substrate in a general flow direction;
-between two consecutive fins, the base body comprises channels oriented transversely with respect to said general direction;
-successive fins form successive intersections according to the air flow, said successive intersections being optionally rotated with respect to each other;
the matrix comprises several groups of successive fins arranged in successive planes behind the air flow, said planes possibly being parallel;
-continuous fins extending from the network area, projected on a plane perpendicular to the air flow, intersecting at a distance from the network area;
-successive fins are adjacent or spaced from each other in the direction of air flow;
the network comprises a plurality of pipes possibly parallel to each other;
the cross section of the tube is oval, drop-shaped or diamond-shaped;
the network comprises walls separating air from oil, from which continuous fins extend;
-the network comprises a mesh;
-the grid has a profile cross-section in the direction of the air flow;
the grid defines channels for the air flow, possibly with quadrangular section;
the matrix is adapted to exchange heat between a liquid and a gas (in particular a gas flow through a turbojet engine);
the continuous fin comprises main portions according to which the main directions are arranged, the main directions of the main portions being inclined with respect to each other;
-the main directions are inclined with respect to each other by at least 5 °, or at least 20 °, or 90 °;
the continuous fins comprise nodes on the network which are laterally offset with respect to the air flow;
the tube forms at least one alignment or at least two alignments, in particular transversely with respect to the air flow;
two consecutive fins connecting adjacent tubes, possibly intersecting in the space between said tubes;
-each fin is solid (not hollow) and/or forms a flat sheet (wafer);
-each fin comprises two opposite ends, both connected to the network;
-the thickness of the continuous fins is between 0.10 and 0.50 mm; or between 0.30 mm and 0.40 mm; or less than the wall thickness;
the continuous fins describe at least one intersection, preferably several intersections;
-the crossings are separated from each other according to the air flow or have material continuity;
-spacing the tubes according to and/or transverse to the air flow;
the grid extends over the entire length and/or the entire width and/or height of the base body;
the network comprises internal protuberances in contact with the oil;
the matrix comprises helical channels formed between the fins, possibly a plurality of coaxial helical channels formed between the fins. Optionally, the coaxial helical channels have the same pitch and/or the same radius.
According to a preferred embodiment of the invention, the heat exchanger has a substantially arcuate shape; the pipe elements may be radially oriented.
The invention also relates to a method for producing a heat exchanger matrix for heat exchange between air and oil, the matrix comprising: a passage for an air flow; a network extending in the channel, in which oil flows; the method comprises the following steps: (a) designing a heat exchanger having a base thereof; (b) manufacturing a substrate by additive manufacturing in a printing direction; wherein step (b) comprises creating fins extending in a main direction inclined with respect to the printing direction.
According to a preferred embodiment of the invention, the fins are arranged in a plane inclined at an angle β of between 20 ° and 60 °, optionally between 30 ° and 50 °, with respect to the printing direction.
According to a preferred embodiment of the invention, step (b) comprises producing a tube inclined at an angle of between 20 ° and 60 °, possibly between 30 ° and 50 °, with respect to the printing direction.
According to a preferred embodiment of the invention, step (b) comprises producing a housing having a wall cooperating with the inner space of the tube.
In general, the preferred embodiments of each object of the present invention are also applicable to other objects of the present invention. Each object of the invention can be combined with other objects and the objects of the invention can also be combined with the embodiments of the description, which can also be combined with each other according to all possible technical combinations, unless otherwise stated. In particular, the heating or cooling of the oil may be multiplexed and independently controllable. For this purpose, the oil circuit is branched or led to the oil channel by means of valves and control means provided for this purpose. Depending on the difference between the measured temperature and the target temperature, some heating or cooling modes may be more efficient than others.
Technical effects
Integrating the heating element into the pump makes it possible to reduce the volume and space occupied by the hydraulic system. Depending on the operating conditions of the fuel cell, it may be necessary to cool or heat the oil, which may conveniently be done by air (cold) or turbine engine components (hot). No heating elements dedicated to the fuel cell are required.
Drawings
FIG. 1 illustrates a system according to the present invention;
FIG. 2 shows a box for a system according to the invention;
FIG. 3 shows an electric pump for use in a system according to the invention;
FIG. 4 shows a front view of a heat exchanger according to the present invention;
fig. 5 shows a front view of a base body of a heat exchanger according to a first embodiment of the invention;
FIG. 6 is an isometric view of a heat exchanger according to the present invention;
FIG. 7 is a cross-section of the substrate taken along line 7-7 shown in FIG. 5;
FIG. 8 shows a front view of a heat exchanger matrix according to a second embodiment of the invention;
FIG. 9 illustrates an enlarged view of the exemplary channel of FIG. 8;
FIG. 10 is a cross-section of the base of the second embodiment taken along line 10-10 shown in FIG. 8;
fig. 11 is a schematic view of a process for producing a heat exchanger according to the present invention.
Detailed Description
In the following description, the terms "inner" and "outer" refer to the positioning relative to the axis of rotation of an axial turbomachine. The axial direction corresponds to a direction along the axis of rotation of the turbine. The radial direction is perpendicular to the axis of rotation. Upstream and downstream refer to the main flow direction of the flow in the turbine.
Fig. 1 is a simplified schematic diagram of an axial turbomachine 2. This is a dual flow turbojet. Turbojet 2 comprises a first compression stage, called low-pressure compressor 4, a second compression stage, called high-
A
A reduction device such as a
The rotor 12 includes a
Fig. 1 also shows a
The two
It is implied that the circuit comprises all the means that can control the temperature, pressure and flow in order to obtain the optimum operation of the
The
To prevent the oil from freezing due to low temperatures, the
The heating element of the
Fig. 2 shows a subassembly of the hydraulic circuit. Two pumps 150, 250 are shown as examples of possible locations for the pumps. The
The subassembly may also contain a
Fig. 3 shows a schematic example of the
The pump may have a
The
The oil may also contact the coils of the
The
Fig. 4 shows a plan view of the
Fig. 5 shows a front view of the
The
The
The intersections 142 of
Fig. 5 also shows the
The base body is manufactured by additive manufacturing, and the tubular shape of the
Fig. 6 is a schematic isometric view of a portion of
Fig. 7 is a cross-section along line 7-7 shown in fig. 5. Due to this cross-section, only half of the
Along the
The
The
Two exemplary embodiments of the
Fig. 8 shows a
The
Three exemplary embodiments of the
They may be linear or zigzag as shown in fig. 7. The
Fig. 9 shows an enlarged schematic view of the
The
Fig. 10 is a partial cross-section taken along line 10-10 shown in fig. 8. Three
The
The angle of inclination β between the
Fig. 11 is a view showing a method of producing a heat exchanger base body. The produced substrate may correspond to the substrate described with reference to fig. 3 to 10.
The method may comprise the following steps, possibly performed in the following order:
(a) design 200 of the base of the exchanger, which comprises a one-piece body with continuous fins;
(b) the substrate 202 is manufactured by additive manufacturing in a printing direction which is inclined relative to the main direction of the or each fin. The angle of inclination may be between 30 ° and 50 °.
The printing direction may be inclined at an angle of between 30 ° and 50 ° with respect to the tube. The printing direction may also be substantially parallel to the channel, or inclined at an angle of less than 10 ° or less than 4 °.
Additive manufacturing may be made from powders, optionally powders of titanium or aluminium. The thickness of the additive manufacturing layer may be between 20 and 50 microns, which makes it possible to achieve a fin thickness on the order of 0.35 mm and a spacer/wall of 0.60 mm.
The collector may be made of mechanically welded sheet material and then welded to the end of the base to form the collector.
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