Device, arrangement and method for cleaning a jet engine

Abstract

The invention relates to a device (30) which can be used for cleaning a jet engine (1) and to an arrangement (10) and method for cleaning a jet engine. The device (30) is used to reduce the proportion of foreign liquid in the engine oil that enters the engine oil system (2) of the jet engine (1) during the cleaning process of the jet engine (1) and comprises supply and discharge lines (31, 32) for the transparent serial intermediate connection of the device (30) into the oil circuit of the engine oil system (2), and a treatment unit (33), which can thus be temporarily integrated into the oil circuit of the engine oil system (2) in order to reduce the foreign liquid content in the engine oil flowing through the treatment unit (33). The arrangement (10) comprises a unit (20) for introducing a liquid cleaning medium into the jet engine (1) and a device (30) according to the invention. The method relates to the operation of the arrangement (10) for cleaning a jet engine (1).

Description

[0001] Device, arrangement and method for cleaning a jet engine

[0002]

[0001] The invention relates to a device which can be used for cleaning a jet engine, as well as to an arrangement and method for cleaning a jet engine.

[0003]

[0002] Jet engines, as is known, have one or more compressor stages, a combustion chamber, and one or more turbine stages. In the turbine stages, the hot combustion gases from the combustion chamber release part of their thermal and mechanical energy, which is used to drive the compressor stages. Bypass jet engines are particularly well known from subsonic commercial aircraft. These engines have an additional airflow around the actual jet engine (also called the "core engine"), which is accelerated by a fan driven by the core engine to generate a large part of the jet engine's propulsion.

[0004]

[0003] Aircraft jet engines become dirty during operation, with the components located upstream of the combustion chamber in the direction of flow becoming dirty by particles in the intake air, while components located downstream of the combustion chamber in the direction of flow can also be contaminated by combustion residues. Any contamination of an aircraft jet engine can lead to a reduction in efficiency, which results in increased fuel consumption and thus increased environmental pollution. This is particularly true if the contamination forms a coating on the parts of an aircraft engine through which air flows, thereby impairing the surface quality.

[0004] It is known in the prior art to clean aircraft jet engines at regular intervals or depending on the individual degree of contamination.In a known cleaning process, the jet engine is rotated, for example, by the starter motor or an external drive, without burning fuel in the combustion chamber (also called "dry cranking"), while liquid cleaning agent is usually injected under high pressure into the jet engine, and in particular the core engine.

[0005]

[0005] During dry rotation, the engine oil system is operated, pumping engine oil through a dedicated oil circuit to lubricate the rotating parts of the jet engine. The engine oil is pumped either by an electrically driven pump or by a pump mechanically coupled to the rotational movement of the jet engine.

[0006]

[0006] During the cleaning process, a portion of the cleaning medium enters the engine oil through gaps inside the jet engine and is distributed throughout the oil circuit due to the pumping of the engine oil. The cleaning medium, especially if it is water-based, can reduce the lubricity of the engine oil, cause corrosion, and accelerate the aging of the engine oil.

[0007]

[0007] To avoid these effects, it is prescribed that, essentially immediately after cleaning a jet engine, the jet engine be operated at least at idle for a prescribed period, so that, in particular, the operating temperature of the jet engine is reached and maintained for a certain period. At operating temperature, all components in the engine oil system for cleaning and dewatering the engine oil become active, so that the cleaning medium that previously penetrated the engine oil is removed from the engine oil.

[0008]

[0008] The disadvantages of this approach are the required expenditure of man-hours and kerosene, as well as the inevitable additional downtime for the jet engine or the aircraft to which the jet engine is attached. The resulting noise and exhaust emissions are also detrimental.

[0009]

[0009] The object of the present invention is to provide a device, an arrangement and a method with which the disadvantages known from the prior art no longer occur or only occur to a reduced extent.

[0010]

[0010] This object is achieved by a device according to claim 1, an arrangement according to claim 8 and a method according to claim 9. Advantageous further developments are the subject of the dependent claims.

[0011]

[0011] Accordingly, the invention relates to a device for reducing the proportion of foreign fluid in the engine oil that enters the engine oil system of the jet engine during the cleaning process, comprising supply and discharge lines provided for the transparent interposition of the device in the oil circuit of the engine oil system and a treatment unit that can thus be temporarily integrated into the oil circuit of the engine oil system for reducing the foreign fluid content in the engine oil flowing through the treatment unit.

[0012]

[0012] Furthermore, the invention relates to an arrangement for cleaning a jet engine, comprising a device for introducing a liquid cleaning medium into the jet engine and a device according to the invention for reducing the proportion of the cleaning medium in the engine oil that enters the engine oil system of the jet engine during the cleaning process.

[0013]

[0013] Furthermore, the invention relates to a method for cleaning a jet engine, in particular the core engine of a jet engine using a device according to the invention or an arrangement according to the invention, comprising the steps of:

[0014] - Interposition of a device according to the invention in the oil circuit of the engine oil system;

[0015] - Dry running of the jet engine;

[0016] - Introduction of liquid cleaning medium; and

[0017] - Operating the intermediate device to reduce the proportion of cleaning agent in the engine oil.

[0018]

[0014] First, some terms used in connection with the invention will be explained.

[0019]

[0015] An interposition of a device in an existing system is considered "transparent" if the generally only temporary interposition of the device does not fundamentally change the functioning of the system and, in particular, does not have to be adapted with regard to the interposed device. If the system is actively operated with an interposed device, the term "transparent" preferably also means that the interposed device is not recognized by any control system and / or cannot be read from measured values ​​recorded during operation. From the perspective of the system, the interposed device is therefore "invisible" - although it is present and in operation.

[0020]

[0016] The invention has recognized that, if the proportion of foreign fluid entering the engine oil during a jet engine cleaning process is sufficiently reduced, idle operation of the jet engine following the cleaning process is no longer necessary. Aside from the fact that this avoids noise and exhaust emissions, the jet engine is ready for use again immediately after cleaning, i.e., there is no additional downtime for idle operation of the jet engine, as required in the prior art.

[0021]

[0017] The invention has recognized that penetration of cleaning fluid as a foreign fluid into the engine oil during cleaning cannot be avoided, which is why the device according to the invention is aimed at directly reducing the proportion of foreign fluid that occurs.

[0022]

[0018] The device according to the invention is designed in such a way that it can be inserted into the oil circuit of the engine oil system in a way that is transparent to the systems of the jet engine. For the systems of the jet engine, it is therefore irrelevant whether the device according to the invention is connected or not. In particular, no adaptation of the jet engine is necessary for the use of the device: the device has at least one, usually exactly one, supply line and at least one, usually exactly one discharge line, with which the device can be easily inserted into the oil circuit. For this purpose, the oil circuit must be opened at a suitable point and connected to the supply and discharge lines of the device in such a way that the device is integrated into the oil circuit or is interposed therein.

[0023]

[0019] As a rule, engine oil systems also have valves, in particular three-way valves, which are provided for filling and / or emptying the engine oil system. Depending on the arrangement and design of these valves, the device according to the invention can also be connected to these valves. The supply and discharge lines of the device according to the invention can also be designed such that they can be used to temporarily replace a fundamentally replaceable component in the engine oil system in order to enable the desired interposition. If, for example, a replaceable oil filter with an inlet and an outlet is provided, the supply and discharge lines of the device according to the invention can be designed such that, after removal of the oil filter, they can be connected to the inlet and outlet provided for the oil filter.Alternatively, it is also possible to temporarily remove a line section or a component of the engine oil system and to interpose the device according to the invention in its place.

[0024]

[0020] Via the supply and discharge lines of the device according to the invention, the treatment unit of the device can be temporarily integrated into the oil circuit of the engine oil system of a jet engine by appropriately connecting it to the engine oil system. Integrating the treatment unit into the oil circuit directly results in engine oil flowing to the treatment unit via the supply line(s) and from there back into the oil circuit via the discharge line(s).

[0025]

[0021] The treatment unit is designed to reduce any foreign fluid present in the engine oil flowing through the treatment unit, and thus the foreign fluid content in the engine oil. The fact that the foreign fluid is at least partially removed from the engine oil as it flows through contributes to transparency when the treatment unit is interposed: the oil withdrawn from the oil circuit of the engine oil system through a supply line is then immediately added back to the oil circuit, so that from the perspective of the engine oil system (apart from a possible reduction in the oil level), no apparent difference can be determined during operation whether the device according to the invention is interposed or not.

[0026]

[0022] The device is preferably serially connected to the oil circuit of the engine oil system. This ensures that the engine oil flowing through the oil circuit of the engine oil system is completely passed through the device and treated there with regard to the foreign fluid content. If the device is integrated into the oil circuit of the engine oil system in parallel with one or more components present there, it must be ensured that a sufficient proportion of the engine oil is passed through the device.

[0027]

[0023] The treatment unit can in principle be designed in any way to reduce the foreign fluid content in the engine oil flowing through it. However, it is preferred if the treatment unit comprises a heating element for heating the engine oil flowing through the treatment unit to a temperature greater than the evaporation temperature of the foreign fluid. By heating the engine oil flowing through the treatment unit to a temperature above the evaporation temperature of the foreign fluid, the foreign fluid evaporates and can escape in gaseous form from the engine oil, which at corresponding temperatures is basically still liquid. The engine oil is heated by the treatment unit, but the resulting temperatures are generally well below those that occur during operation of the jet engine.Of course, when using the treatment unit, care should be taken not to exceed the maximum permissible temperature for the engine oil. Since cleaning agents used as external fluids are often water-based, it is preferable if the temperature to which the engine oil flowing through the treatment unit is heated exceeds 100°C. This temperature is usually sufficient to evaporate a water-based cleaning agent contained in the engine oil.

[0028]

[0024] The foreign fluid converted into the vapor or gas phase by the increase in temperature can escape from the oil circuit through outlets provided for gas in the oil circuit of the engine oil system. However, it is also possible for the treatment unit itself to have an outlet for removing foreign fluid from the engine oil. It is possible for the foreign fluid to exit directly as vapor through the outlet of the treatment unit. However, it is also possible for the outlet to comprise a condenser unit with which the foreign fluid vapor escaped from the engine oil is returned to the liquid phase and then exits the treatment unit as liquid. In particular, heat generated during the condensation of the foreign fluid can be returned and used to heat the engine oil in the treatment unit.

[0029]

[0025] Alternatively or additionally, the treatment unit may comprise a separator, in particular a coalescence separator and / or a vortex separator, with which at least foreign fluids, such as cleaning agents, can be separated from the engine oil flowing through the treatment unit. These separators are also suitable for continuous operation and thus for the transparent interposition of the device according to the invention into the oil circuit of the engine oil system. With such a separator, foreign particles that enter the engine oil during the cleaning process can generally also be separated from the engine oil.

[0030]

[0026] In addition to the design of the treatment unit for reducing the foreign fluid content, the device can also comprise at least one filter for the engine oil. With such a filter, for example, foreign particles that enter the engine oil during the cleaning process or any suspended matter that may remain after the foreign fluid has been heated and evaporated can be filtered out. A corresponding filter can be arranged on the supply or discharge side of the treatment unit. Because the treatment unit comprises a filter with which foreign particles that arise in the engine oil, in particular during the cleaning process, can be filtered out, these particles do not have to be filtered out by the other filters generally provided in the engine oil system, which can have a positive effect on their service life.For this purpose, the device according to the invention only needs to be interposed in the flow direction upstream of the filters of the engine oil system.

[0031]

[0027] Even if the device according to the invention, and in particular the treatment unit, is already fundamentally designed for transparent serial interposition in the oil circuit of the engine oil system, the device may nevertheless exhibit an undesirable increased flow resistance. To compensate for this, the device may comprise an auxiliary pump for transparently conveying the engine oil through the treatment unit. This auxiliary pump promotes the flow of the engine oil through the device in such a way that, from the perspective of the engine oil system, the flow resistance between the connection points of the supply and discharge lines remains virtually unchanged due to the interposition of the device.

[0032]

[0028] The device is preferably part of an arrangement which, in addition to the device according to the invention itself, also includes a device for introducing a liquid cleaning medium into the jet engine. Corresponding devices for introducing a liquid cleaning medium are known from the prior art, for example from EP 1 970 133 A1. In the arrangement according to the invention, the device according to the invention is intended to be able to at least partially remove from the engine oil any cleaning agent introduced by the said device and which may enter the engine oil. As a result, if the proportion of foreign fluid in the engine oil is sufficiently reduced, despite the cleaning of a jet engine with liquid cleaning medium, subsequent start-up of the engine and operation at idle can be dispensed with.

[0033]

[0029] The method according to the invention relates precisely to this: Before the jet engine is cleaned in a known manner with a liquid, in particular and preferably water-based, cleaning medium during dry running, a device according to the invention is interposed at a suitable point in the oil circuit of the engine oil system in order to then be operated during the cleaning process and / or after its completion. Any cleaning medium that may enter the engine oil can then be immediately at least partially removed from the engine oil by the device according to the invention. If the reduction of the foreign liquid content in the engine oil is sufficient, the start-up of the jet turbine engine, which is customary in the prior art and currently still partly prescribed, can be dispensed with.

[0034]

[0030] The invention will now be described by way of example using an advantageous embodiment with reference to the accompanying drawings. They show:

[0035] Figure 1: a schematic representation of an embodiment of an arrangement according to the invention comprising a device according to the invention.

[0036]

[0031] Figure 1 schematically shows an arrangement 10 according to the invention using a device 20 according to the invention, and thus the implementation of the method according to the invention for cleaning a jet engine 1.

[0037]

[0032] In this case, only some of the components of the engine oil system 2 of the jet engine 1 are sketched, apart from the outline. Engine oil is pumped from an oil tank 3 by means of a pressure pump 4. The pressure pump 4 is mechanically coupled to the jet engine 1 in such a way that rotation of the shaft of the jet engine 1 directly causes it to be pumped by the pressure pump 4. The oil pumped in this way is first fed into one or more cooler elements 5, in which the oil can be cooled by means of heat exchange with air and / or fuel supplied to the jet engine 1, at least during operation of the jet engine 1, before it is then fed under pressure via the interface 6 to the various components of the jet engine 1 that are to be lubricated and are not shown for reasons of clarity, such as bearings.

[0038]

[0033] After the engine oil has passed through the components to be lubricated, it returns via the interface 7 to the part of the engine oil system 2 shown in Figure 1, where it first enters the return oil pump 8, which, during normal operation, pumps the engine oil through the filter 9 back into the oil tank 3. The return oil pump 8, like the pressure pump 4, can also be mechanically coupled to the jet engine 1.

[0039]

[0034] The described engine oil system 2 is a conventional design for a jet engine 1.

[0040]

[0035] Also known in principle from the prior art is the device 20 for introducing a liquid cleaning medium into the jet engine 1. The device 20 comprises a cleaning agent tank 21, from which the cleaning agent is conveyed by a pump 22 to a nozzle arrangement 23, with which the liquid cleaning medium is generally introduced at high pressure into the jet engine 1. The nozzle arrangement 33 shown in Figure 1 is for illustration purposes only. Any other nozzle arrangements are also conceivable, in particular those which are attached to the jet engine 1 itself. Examples of such nozzle arrangements can be found, for example, in US Pat. Nos. 5,868,860, WO 2005 / 120953 A1, or EP 1 970 133 A1.

[0041]

[0036] The device 20 is part of the arrangement 10, which also includes the device 30.

[0042]

[0037] The device 30 serves to reduce the proportion of foreign liquid in the engine oil that enters the engine oil system 2 of the jet engine 1 during the cleaning process with liquid cleaning agent, namely the liquid cleaning medium itself. During the cleaning of the jet engine 1, the liquid cleaning medium enters the engine oil system 2 via gaps etc., particularly in the area of ​​the bearings in the jet engine 1. The jet engine 1 is rotated dry during cleaning - that is, without injection and combustion of fuel - and due to the mechanical coupling of pressure pump 4 and return oil pump 8, the engine oil is pumped through the oil circuit of the engine oil system 2. As a result, the foreign liquid that enters at various points is distributed in the engine oil.

[0043]

[0038] In order to reduce the proportion of foreign fluid or cleaning agent in the engine oil, the device 30 has an inlet connection 31 and an outlet connection 32, with which the device 30 can be interposed in the oil circuit of the engine oil system 2. The interposition is transparent to the engine oil system 2.

[0044]

[0039] In the illustrated embodiment, the filter 9 of the engine oil system 2 is bridged by the supply and discharge lines 31, 32 of the device 30, so that the engine oil flows exclusively through the device 30 instead of through the filter 9. Alternatively, the device 30 can also be connected between the return oil pump 8 and the filter 9, as indicated by the dashed line for the discharge line 32'. In this case, too, the engine oil flows completely through the device 30, before subsequently also flowing through the filter 9. In both cases, the device 30 is therefore serially interposed in the oil circuit of the engine oil system 2.

[0045]

[0040] In both cases, engine oil pumped through the oil circuit by means of pumps 4 and 8 flows through the device 30. It is drained from the oil circuit via the supply line 31 and fed back through the discharge line 32.

[0046]

[0041] The device 30 further comprises a treatment unit 33, with which foreign fluid can ultimately be removed from the engine oil flowing through the device 30. The treatment unit 33 comprises a heating element 34 for heating the engine oil flowing through the treatment unit to a temperature greater than the evaporation temperature of the foreign fluid. Since in the present embodiment the cleaning medium is water-based and has an approximate vapor temperature of 100°C, the heating element 34 is designed such that engine oil flowing through it is heated to approximately 120°C. As a result, the cleaning agent evaporates and is discharged from the device 30 via the outlet 35 either directly in vapor form and / or in liquid form after condensation.The engine oil returned from the device 30 into the engine oil system 2 consequently has at least a lower proportion of foreign fluid.

[0047]

[0042] Filters may be provided at the outlet 35, if necessary, to clean the escaping steam. It is also possible for the steam to be collected and recondensed into a liquid, which can then be disposed of in the usual way.

[0048]

[0043] The device 30 further comprises a filter 36, with which the engine oil supplied to the treatment unit 33 is filtered. This filter 36, which can be finer than the filter 9 provided in the engine oil system 2, filters out solids that enter the engine oil system 2 together with the cleaning medium.

[0049]

[0044] In order to nevertheless ensure that the device 30 is completely transparent for the engine oil system 2 and that the return oil pump 8 does not issue a warning due to increased pumping resistance, which can arise, among other things, from the filter 36, but also from the line resistances of the supply and discharge lines 31, 32, the device 30 further comprises an auxiliary pump 37. The auxiliary pump 37 is designed and controlled in such a way that for the engine oil system 2 between the connection points of the supply and discharge lines 31, 32, neither an increased flow resistance is noticeable, nor can a higher pressure loss be detected than when the engine oil system 2 is operated without an intermediate device 30.

[0050]

[0045] The method for cleaning the jet engine 1 follows directly from the above: After the arrangement 10, as shown in Figure 1, has been arranged and connected, liquid cleaning agent is introduced into the jet engine 1 by the device 20 while the latter is being rotated dry. In parallel, the device 30 is operated, with which liquid cleaning agent which almost inevitably gets into the engine oil is almost immediately removed from the engine oil or at least its content is greatly reduced. By using the device 30, it is ideally possible to dispense with the otherwise necessary operation of the jet engine 1 at idle after engine cleaning in order to free the engine oil of foreign liquids.

Claims

Patent claims 1. Device (30) for reducing the proportion of foreign liquid in the engine oil which enters the engine oil system (2) of the jet engine (1) during the cleaning process of a jet engine (1), comprising supply and discharge lines (31, 32) provided for the transparent interposition of the device (30) in the oil circuit of the engine oil system (2) and a treatment unit (33) which can thus be temporarily integrated into the oil circuit of the engine oil system (2) for reducing the foreign liquid content in the engine oil flowing through the treatment unit (33).

2. Device according to claim 1, characterized in that the intermediate circuit of the device is a serial intermediate circuit.

3. Device according to one of the preceding claims, characterized in that the treatment unit (33) has a heating element (34) for heating the engine oil flowing through the treatment unit (33) to a temperature greater than the evaporation temperature of the foreign liquid, preferably greater than 100°C.

4. Device according to claim 3, characterized in that the treatment unit (33) comprises an outlet (35) for removing foreign fluid from the engine oil.

5. Device according to one of the preceding claims, characterized in that the treatment unit (33) comprises a separator, preferably a coalescence separator and / or a vortex separator for separating at least the foreign fluid from the engine oil.

6. Device according to one of the preceding claims, characterized in that the device (30) comprises at least one filter (36) for the supplied and / or discharged engine oil.

7. Device according to one of the preceding claims, characterized in that the device (30) comprises an auxiliary pump (37) for conveying the engine oil through the device (30) in a manner transparent to the engine oil system (2).

8. Arrangement (10) for cleaning a jet engine (1), comprising a device (20) for introducing a liquid cleaning medium into the jet engine (1) and a device (30) according to one of claims 1 to 7 for reducing the proportion of the cleaning medium in the engine oil that enters the engine oil system (2) of the jet engine (1) during the cleaning process.

9. Method for cleaning a jet engine (1), in particular the core engine of a jet engine (1) using a device (30) according to one of claims 1 to 7 or an arrangement according to claim 8, comprising the steps: Interposing a device (30) according to one of claims 1 to 7 in the oil circuit of the engine oil system (2); Dry running of the jet engine (1); - Introduction of liquid cleaning medium; and - Operating the intermediate device (30) to reduce the proportion of cleaning medium in the engine oil that has entered it.

10. The method according to claim 9, characterized in that the cleaning medium is water-based.

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