Aircraft with hovering capability and method for lubricating a module of a transmission unit of said aircraft

Abstract

An aircraft (1) is described, comprising a transmission unit (9) having a first module (11, 13, 15) and a lubrication system (25, 25'); the first module (11, 13, 15) comprising a housing (20) and movable components (17, 18, 19); the lubrication system (25, 25') comprising a manifold (26), nozzles (27, 28) supplied with lubrication fluid and designed to supply the lubrication fluid to the interior of the housing (20) of the first module (11, 13, 15), a collection tank (30, 100') for the lubrication fluid sprayed by the nozzles (27, 28) and a lubrication system (25, 25') designed to A recirculation device (35) is designed to recirculate lubricating fluid from a collection tank (30, 100') to a supply manifold (26); a first module (11, 13, 15) comprises a valve (60, 60') which can be used in a first configuration when the pressure of the lubricating fluid in the manifold (26) is greater than a threshold value and in a second configuration when the pressure of the lubricating fluid in the manifold (26) is less than the threshold value, wherein in the first configuration, the valve enables the lubricating fluid to flow out of the module (11) to the recirculation device (35); and in the second configuration, the valve fluidically isolates the module (11) from the recirculation device (35).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority from European Patent Application No. 19219920.6 filed on December 27, 2019, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The invention relates to an aircraft with hovering capability, in particular to a thrust-reversing aircraft or a helicopter.

[0004] The invention also relates to a method for lubricating a module of a transmission unit of an aircraft having hovering capabilities. Background Art

[0005] As is known, helicopters are usually equipped with a transmission unit designed to transmit the driving force from one or more turbines to the main rotor and / or the tail rotor and / or from the turbines to a plurality of auxiliary devices, i.e. for example for providing the power required for operating the flight instruments.

[0006] The transmission unit in turn includes a plurality of movable members coupled to one another, including a plurality of gears.

[0007] In a known manner, a lubricating fluid, typically oil, circulates inside the transmission unit both for lubricating and for cooling the movable components of the transmission unit.

[0008] The transmission unit includes:

[0009] - multiple successive phases; and

[0010] - A lubrication system designed to lubricate the movable components and certain areas to be lubricated of the above-mentioned modules.

[0011] In more detail, each pair of gear wheels forms a corresponding stage of the transmission unit.

[0012] The transmission unit also includes:

[0013] - a housing defining a containment housing; and

[0014] - One or more stages housed in a housing.

[0015] According to a first solution, known as "splash lubrication", the module is filled to a certain level with lubricating oil. The lubricating oil partially covers the gears. Thus, the movement of the gears sprays the lubricating oil towards the area of ​​the module to be lubricated.

[0016] According to another solution, known as “forced oil lubrication”, the lubrication system comprises a recirculation circuit that delivers lubricating oil to and from the casing of each module.

[0017] The recirculation loop includes:

[0018] - Collection header for lubricating oil;

[0019] a plurality of nozzles supplied with lubricating oil by a pump and designed to inject the lubricating oil under pressure into the area to be lubricated of the module; and

[0020] - A delivery pump which sucks in the lubricating oil sprayed by the nozzles, pressurizes it and recirculates it to the nozzles.

[0021] The "forced oil lubrication" solution can be either a wet sump type or a dry sump type.

[0022] In the wet tank solution, the housing of the module defines a corresponding collection tank for the lubricating oil injected by the nozzle. A delivery pump draws this lubricating oil from the tank of the housing.

[0023] In the dry sump solution, the lubrication system consists of:

[0024] - another pump, denoted as recovery pump common to all modules; and

[0025] - a tank common to all modules, separate from the housings of the modules and fluidically connected to said housings.

[0026] A recovery pump draws the lubricating oil from the casing and makes it available in a common tank.

[0027] The transfer pump draws the lubricating oil from this common tank, which is separate from the casing, and delivers it to the common header.

[0028] In both scenarios described above, there is a risk that the lubrication oil pressure drops below a threshold level, for example in the event of a malfunction in the lubrication system.

[0029] In this case, there is a risk of preventing the transmission unit from functioning correctly and deteriorating the helicopter's operational capabilities.

[0030] Therefore, the industry recognizes the need to maintain a certain level of operation of the modules of the transmission unit even in the event of a failure of the lubrication system.

[0031] The industry also recognizes the need to quickly identify and signal fault conditions in lubrication systems.

[0032] EP-A-0068677 discloses a helicopter transmission system having a gearbox, the gearbox comprising a transmission box having a hollow stub shaft, through which the operating load is transmitted from the main support rotor to the fuselage structure. One or more input reduction gear trains are individually supported in a hollow cam portion supported from the shaft, the cam portion or each cam portion having a separate lubricating oil groove and a circulation device, the circulation device being suitable for circulating the lubricating oil to the corresponding gear train. Preferably, an interconnection device is provided to connect the individual oil grooves, and the valve device is suitable for maintaining the flow of lubricating oil in the event of a loss of oil from one of the oil grooves. US2018 / 106360 discloses an aircraft having hovering capability. Summary of the invention

[0033] The object of the present invention is the production of an aircraft capable of hovering that satisfies at least one of the above-mentioned needs in a simple and inexpensive manner.

[0034] The present invention achieves the above-mentioned objectives because it relates to an aircraft with hovering capability, the aircraft comprising:

[0035] - a motion transmission unit consisting of at least one first module; and

[0036] - a lubrication system designed to lubricate the motion transmission unit;

[0037] The first modules include:

[0038] - housing; and

[0039] - one or more movable members housed within said housing;

[0040] The lubrication system comprises:

[0041] - lubrication fluid supply manifold;

[0042] - at least one nozzle, to which said lubricating fluid from said supply manifold can be fluidly supplied and which is designed to supply said lubricating fluid to the interior of said housing of said first module so as to be able to lubricate said associated movable member;

[0043] - a collecting tank for the lubricating fluid sprayed by the nozzle; and

[0044] - a recirculation device designed to recirculate said lubricating fluid from said collection tank to said supply manifold;

[0045] characterised in that at least the first module comprises a valve which can be used in a first configuration when the pressure of the lubricating fluid in the supply manifold is greater than a threshold value, in which first configuration the lubricating fluid is enabled to flow out of the first module to the recirculation device;

[0046] The valve is operable in a second configuration when the pressure of the lubrication fluid within the supply manifold is less than the threshold value, in which the valve fluidly isolates the first module from the recirculation device and is capable of retaining the lubrication fluid within the housing.

[0047] The present invention also relates to an aircraft with hovering capability, the aircraft comprising:

[0048] - a motion transmission unit consisting of at least one first module; and

[0049] - a lubrication system designed to lubricate the motion transmission unit;

[0050] The first module further comprises:

[0051] - housing; and

[0052] - one or more movable members housed within said housing;

[0053] The lubrication system comprises:

[0054] - lubrication fluid supply manifold;

[0055] - at least one nozzle, to which said lubricating fluid from said supply manifold can be fluidly supplied and which is designed to supply said lubricating fluid to the interior of said housing of said first module so as to be able to lubricate said associated movable member;

[0056] - a collecting tank for the lubricating fluid sprayed by the nozzle; and

[0057] - a recirculation device designed to recirculate said lubricating fluid from said collection tank to said supply manifold;

[0058] at least the first module comprises a valve operable in a first configuration when the pressure of the lubricating fluid in the supply manifold is greater than a threshold value, in which first configuration the lubricating fluid is enabled to flow out of the first module to the recirculation device;

[0059] the valve being operable in a second configuration when the pressure of the lubrication fluid within the supply manifold is less than the threshold value, in which second configuration the valve fluidically isolates the first module from the recirculation device;

[0060] The aircraft also includes:

[0061] a recovery pump having an inlet and an outlet fluidly connected to the housing; the collection tank being fluidly isolated from the housing; and

[0062] - a fluid line extending between the valve and the housing;

[0063] The recirculation device includes a transfer pump having an inlet fluidly connected to the collection tank and a discharge port fluidly connected to the supply header;

[0064] The valve is inserted between the discharge port of the recovery pump and the collection tank;

[0065] the valve fluidly connects the discharge port of the recovery pump to the collection tank and fluidly isolates the discharge port of the recovery pump from the fluid line when disposed in the first configuration;

[0066] the valve fluidly connects the exhaust port to the fluid line and fluidly isolates the exhaust port from the collection tank when disposed in the second configuration;

[0067] Characterized in that the fluid pipeline is directly inserted between the valve and the nozzle of the first module;

[0068] the valve is automatic and movement of the valve between the first configuration and the second configuration is automatically determined by the value of the pressure within the supply manifold;

[0069] The valve further comprises:

[0070] -case;

[0071] - a plunger which slides within the housing between a first position and a second position corresponding to the first configuration and the second configuration, respectively;

[0072] - elastic means, interposed between the housing and the plunger and designed to elastically push the plunger towards the second position; and

[0073] - a chamber defined between said housing and said plunger, fluidly connected to said supply manifold and configured to exert an action on said plunger opposite to that exerted by said elastic means and directed, in use, towards said first position;

[0074] The valve further comprises:

[0075] - a first opening fluidly connected to said fluid line;

[0076] - a second opening fluidly connected to the discharge port of the recovery pump; and

[0077] - a third opening fluidly connected to the collection tank;

[0078] When the plunger is disposed in the first position and the valve is disposed in the first configuration, the plunger blocks the first opening and places the second opening and the third opening in fluid communication with each other;

[0079] When the plunger is disposed in the second position and the valve is disposed in the second configuration, the plunger blocks the third opening and places the first opening and the second opening in fluid communication with each other;

[0080] The aircraft further includes a sensor designed to provide an indication associated with whether the valve is in the first configuration or the second configuration;

[0081] The sensor is a pressure sensor or a pressure switch and is configured to provide a signal associated with the pressure of the supply manifold when the valve is in the first configuration;

[0082] The housing includes a fourth opening operatively connected to the sensor;

[0083] The sensor is configured to detect pressure within the fourth opening;

[0084] the plunger obstructing the fourth opening in use when the valve is in the first configuration or the second configuration;

[0085] The plunger opens the fourth opening and places the fourth opening in fluid communication with the supply manifold when the valve is in the other of the first configuration and the second configuration.

[0086] The present invention also relates to a method for lubricating modules of a transmission unit of an aircraft having hovering capability, in which method, each of the modules comprises: a housing; and a movable member housed in the housing. The method comprises the following steps:

[0087] i) collecting the lubrication fluid in a supply header;

[0088] ii) supplying the lubricating fluid contained in the supply manifold into the housing to enable lubrication of the movable components of the module; and

[0089] iii) recirculating the lubrication fluid delivered into the housing to the supply header;

[0090] It is characterized in that it comprises the following steps:

[0091] iv) when the pressure of the lubrication fluid within the supply manifold is greater than a threshold, setting a valve of the module to a first configuration in which the valve allows recirculation of the lubrication fluid to the supply manifold; and

[0092] v) when the pressure of the lubrication fluid within the supply manifold is less than a threshold value, placing the valve into a second configuration in which the valve prevents the recirculation and retains the lubrication fluid within the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] For a better understanding of the invention, two preferred embodiments are described below by way of non-limiting examples only and with reference to the accompanying drawings, in which:

[0094] - Figure 1 is a perspective view of an aircraft having hovering capability manufactured in accordance with the requirements of the present invention, with portions removed for clarity;

[0095] - Figure 2 is combined with Figure 1 Functional diagram of a first embodiment of a lubrication system in a transmission unit of a helicopter;

[0096] - Figure 3 and Figure 4 Shows Figure 2 a section of a lubrication system valve in a corresponding operating configuration, with parts removed for clarity;

[0097] - Figure 5 is combined with Figure 1 A functional diagram of a second embodiment of a lubrication system in a helicopter; and

[0098] - Figure 6 and Figure 7 yes Figure 5 0014 FIG. 1 is a longitudinal section through a valve of a lubrication system with parts removed for clarity. DETAILED DESCRIPTION

[0099] Reference Figure 1 , reference numeral 1 denotes a helicopter, which basically comprises:

[0100] - fuselage 2;

[0101] - one or more turbines 5 equipped with corresponding output shafts 10;

[0102] - a main rotor 3 located on top of the fuselage 2 and rotatable about an axis A; and

[0103] An anti-torque rotor 4 located at the rear end of the fuselage 2 and rotatable about its axis B, which is transverse to the axis A.

[0104] Each rotor 3, 4 comprises a corresponding main shaft 6a, 6b, and a corresponding blade 7, 8 is hinged on the main shaft 6a, 6b.

[0105] The helicopter 1 also comprises a transmission unit 9 known per se, which transmits the power coming from the turbine 5 to the main shafts 6a, 6b to allow the respective rotors 3, 4 to operate.

[0106] The transmission unit 9 in turn comprises a plurality of movable components, in particular gear wheels, interposed between the turbine 5 and the main shafts 6a, 6b.

[0107] The transmission unit 9 also comprises a plurality of stages, each stage being formed by an associated pair of the above-mentioned gears meshing with each other.

[0108] The transmission unit 9 also includes:

[0109] a pair of input gears 17 which transmit the motion from the respective output shaft 10 to the respective intermediate shaft 12 ; and

[0110] A main gear train 18 which transmits the movement from the intermediate shaft 12 to the main shaft 6a.

[0111] The transmission unit 9 also includes:

[0112] - an intermediate shaft 14 driven by a gear train 18; and

[0113] A pair of gears 19 which transmit the movement from the intermediate shaft 14 to the main shaft 6 b of the rotor 4 .

[0114] A plurality of pairs of gears 17 , 19 meshing with one another and a gear train 18 form respective stages of the transmission unit 9 .

[0115] The transmission unit 9 further comprises a plurality of modules 11 , 13 , 15 .

[0116] Each module 11, 13, 15 basically includes ( Figure 2 ):

[0117] - one or more pairs of corresponding gears 17, 19 and gear trains 18 meshing with each other;

[0118] - a housing 20 (shown only schematically) for housing the associated pair of gears 17, 19 and the gear train 18.

[0119] Reference Figure 2 The helicopter 1 further comprises a lubrication system 25 designed to deliver lubricating oil to certain areas of the transmission unit 9 .

[0120] exist Figure 2 In the case shown, the lubrication system 25 is of the wet sump forced recirculation type.

[0121] The lubrication system 25 basically comprises:

[0122] - a supply manifold 26 for lubricating oil;

[0123] a plurality of nozzles 27, 28, which are fluidically connected to the manifold 26 and are designed to spray lubricating oil into the areas to be lubricated of the respective modules 11, 13, 15 and into the interior of the respective housing 20; and

[0124] A collecting sump 30 for the lubricating oil sprayed from the nozzles 27 , 28 into the interior of the respective module 11 , 13 , 15 .

[0125] The header 26 and the oil sump 30 are common to the modules 11 , 13 , 15 .

[0126] The oil sump 30 is also integral with the housing 20 of the module 11 , 13 , 15 .

[0127] The lubrication system 25 also includes a recirculation circuit 35 for delivering lubrication oil from the sump 30 to the header 26 .

[0128] The recirculation loop 35 in turn comprises:

[0129] a pair of pumps 36 having respective inlet ports 37 fluidly connected to the oil sump 30;

[0130] a pair of non-return valves 38 fluidly connected to respective discharge ports 39 of respective pumps 36;

[0131] - one or more discharge valves 40 connected to the check valve 38 and the manifold 26;

[0132] - a filter 42 connected to the drain valve 40; and

[0133] A cooler 43 inserted between the filter 42 and the header 26 .

[0134] The recirculation loop 35 also includes:

[0135] a bypass valve 49 fluidly interposed between the drain valve 40 and the cooler 43 , the bypass valve 49 bypassing the filter 42 ; and

[0136] A thermostatic bypass valve 50 is inserted between the filter 42 and the manifold 26 , which bypasses the cooler 43 .

[0137] Since the modules 11 are identical to one another, only one module 11 will be mentioned hereinafter.

[0138] Advantageously, the module 11 comprises a valve 60:

[0139] - The valve 60 can be in a first configuration ( Figure 3) is used, in which first configuration the valve 60 allows the lubricating oil to flow from the module 11 to the recirculation circuit 35; and

[0140] - The valve 60 can be in the second configuration ( Figure 4 ) is used, in this second configuration, the valve 60 fluidly isolates the module 11 from the recirculation circuit 35 and allows the lubrication fluid to be retained within the housing 20.

[0141] In more detail, lubrication oil is typically present within the manifold 26 at a pressure above a threshold to maintain the valve 60 in the first configuration.

[0142] Conversely, when the pressure of the lubrication fluid drops below a threshold value, for example in the event of a malfunction in the lubrication system 25 , the valve 60 moves from the first configuration to the second configuration.

[0143] When the valve 60 is set to the second configuration ( Figure 4 ), the housing 20 of the module 11 becomes substantially sealed and the lubricating oil level within the housing 20 remains substantially constant, thereby maintaining lubrication of the module 11 due to the fact that the lubricating oil is sprayed to the area to be lubricated of the gear 17 contained in the module 11.

[0144] In other words, in the event of a malfunction of the lubrication system 25 , the arrangement of the valve 60 in the second configuration results in a transition from forced oil lubrication of the housing 20 to splash lubrication of the housing 20 .

[0145] In the embodiment shown, the valve 60 is of the automatic type, ie it has no external control members.

[0146] More specifically, the valve 60 automatically moves from the first configuration to the second configuration based on the pressure within the manifold 26 .

[0147] Reference Figure 3 and Figure 4 , the housing 20 comprises:

[0148] a lower part 61 in which the lubricating oil sprayed by the nozzle 27 is collected and which houses the valve 60 ; and

[0149] - opening 62, which is connected to the oil groove 30 (not shown in Figure 3 ) and the lower portion 61 are fluidly connected.

[0150] In the case shown, the opening 62 is circular.

[0151] The valve 60 basically comprises:

[0152] - a housing 65 fixed to the lower part 61 of the housing 20;

[0153] - a plunger 66 which is in a first position ( Figure 3 ) and the second position ( Figure 4 ) and

[0154] A spring 69 , which is inserted between the housing 65 and the plunger 66 and is designed to elastically push the plunger 66 towards the second position.

[0155] In the case shown, the spring 69 is of the helical type.

[0156] The plunger 66 includes respective axial end portions 67 , 68 opposed to each other and a rod 70 axially inserted between the end portions 67 , 68 .

[0157] The end portion 68 is shaped like a flange that projects radially from the stem 70 in a cantilevered manner, with a diameter greater than the diameter of the stem 70 and corresponding to the diameter of the opening 62 .

[0158] The plunger 66 also includes a flange 77 adjacent the end 67 and having a larger diameter than the stem 70 .

[0159] The valve 60 also includes:

[0160] - Chamber 74, which is bounded by housing 65 and connected by fluid line 85 ( Figure 2 ) is fluidly connected to the header 26; and

[0161] A chamber 75 which is fluidically connected to the chamber 74 via a plurality of openings 76 .

[0162] The chamber 75 is delimited by the housing 65 and the flange 77 of the plunger 66 and therefore has a variable volume depending on the position of the plunger 66 along the axis E.

[0163] In the case shown, the openings 76 are axially and angularly equidistant about the axis E.

[0164] The valve 60 also includes a plurality of openings 72 formed in the housing 65 .

[0165] The openings 72 are angularly equidistant about the axis E.

[0166] End 67 contacts spring 69 and end 68 is received in lower portion 61 .

[0167] The plunger 66 is subject to opposing forces generated by the spring 69 acting on the end 67 and the pressure of the lubricating oil in the chamber 75 on the flange 77. This pressure is equal to the pressure in the manifold 26.

[0168] The valve 60 is configured such that:

[0169] - When the pressure is above the threshold, the effect of the pressure of the lubricating oil on the flange 77 overcomes the elastic effect of the spring 69, thereby moving the valve 60 to the first configuration and the plunger 66 to the first position ( Figure 3 );as well as

[0170] - When the pressure is below the threshold, the effect of the pressure of the lubricating oil on the end 67 is not sufficient to overcome the elastic effect of the spring 69, so that the valve 60 moves to the second configuration and the plunger 66 moves to the second position ( Figure 4 ).

[0171] In particular, when the plunger 66 is in the first position, the end 68 is spaced apart from the opening 62 and lubricating oil continues to flow from the housing 20 to the oil sump 30 through the opening 62 .

[0172] When the plunger 66 is in the second position, the end 68 abuts against and seals the opening 62 , thereby preventing the flow of lubricating oil through the opening 62 .

[0173] When the plunger 66 is in the first position and the valve 60 is in the first configuration ( Figure 3 ), the opening 72 is inserted between the flange 77 and the chamber 74 along the axis E. In this way, the chamber 75 is in fluid communication with the opening 72.

[0174] Conversely, when the plunger 66 is in the second position and the valve 60 is in the second configuration ( Figure 4 ), the flange 77 is inserted along the axis E between the opening 72 and the chambers 74, 75.

[0175] In this way, chamber 75 is fluidly isolated from opening 72 .

[0176] When the plunger 66 is in Figure 3 In the first position, chamber 75 has a larger volume, while plunger 66 is in Figure 4 In the second position, chamber 75 has a smaller volume.

[0177] The housing 65 also includes a chamber 90 that houses the spring 69 and is in fluid communication with the lower portion 61 of the shell 20 through a plurality of openings 91 formed in the housing 65 .

[0178] Thus, the lubricating oil in chamber 90 is at the same pressure as the lubricating oil in lower portion 61 of housing 20. Therefore, the resultant force 90 on plunger 66 from the pressure of the lubricating oil contained in chamber 90 and acting on end 68 is zero.

[0179] When the plunger 66 is in Figure 4 In the second position shown, the chamber 90 is in fluid communication with the opening 72 .

[0180] The lubrication system 25 comprises a pressure sensor 150 which is designed to detect the pressure in the opening 72 of the housing 65 .

[0181] When the valve 60 is set in the second configuration and the plunger 66 is in the second position ( Figure 4 ), the opening 72 is fluidly isolated from the chamber 75 and fluidly connected to the housing 20.

[0182] The pressure sensor 150 detects a pressure value of the lubricating oil which is lower than a threshold value and equal to the pressure of the lubricating oil in the housing 20 and is therefore substantially zero.

[0183] In contrast, when the valve 60 is set in the first configuration and the plunger 66 is in the first position ( Figure 3 ), the opening 72 is fluidically connected to the chamber 75. Thus, the pressure sensor 150 detects a pressure value that is higher than the threshold and equal to the pressure value in the chamber 75 and therefore equal to the pressure value in the manifold 26.

[0184] In this manner, the pressure readings provided by pressure sensor 150 clearly indicate:

[0185] - valve 60 is in the second configuration and therefore recommends a rapid landing of helicopter 1 ; or

[0186] The valve 60 is in the first configuration and the lubrication system 15 operates normally.

[0187] In the case shown, the module 13 does not comprise a valve 60 .

[0188] In use, the turbine 5 drives the main shaft 6 a , 6 b of the respective rotor 3 , 4 in rotation via the transmission unit 9 .

[0189] In more detail, gear 17 of module 11 transmits movement from output shaft 10 of corresponding turbine 5 to intermediate shaft 12, gear 18 of main module 13 transmits movement from intermediate shaft 12 to main shaft 6a, and gear 19 of module 15 transmits movement from intermediate shaft 14 to main shaft 6b.

[0190] The lubrication system 25 ensures proper lubrication of the modules 11 , 13 , 15 and the corresponding gears or gear trains 17 , 18 , 19 .

[0191] In more detail, the lubricating oil contained in the header 26 is delivered to the nozzles 27 , 28 and sprayed through these nozzles to the areas to be lubricated of the modules 11 , 13 and 15 and the interior of the corresponding housing 20 .

[0192] Additionally, lubrication oil flows from the manifold 26 to the chambers 74 , 75 of the valve 60 through the fluid line 85 .

[0193] The lubricating oil is then collected in the oil sump 30 and delivered again to the header 26 via the recirculation loop 35 .

[0194] More specifically, the pump 36 draws lubricating oil from the oil sump 30 and pumps it to the check valve 38 , the drain valve 40 , the filter 42 , and the cooler 43 .

[0195] The operation of the lubrication system 25 is described below only for the module 11 and starting from the case where the pressure of the lubrication oil is greater than a threshold value.

[0196] This situation substantially corresponds to a situation of normal and correct operation of the lubrication system 25 .

[0197] In this case, the valve 60 is in the first configuration and the plunger 66 is in the first position ( Figure 3 ). Manifold 26 is also fluidly connected to chamber 74 and to chamber 75 through opening 76 .

[0198] In this case, the pressure exerted by the lubricating oil in the chamber 75 acts on the flange 77 of the plunger 66 and overcomes the action of the spring 69 on the end 67.

[0199] Furthermore, the opening 72 is interposed between the flange 77 and the chambers 74 , 75 along the axis E. The opening 72 is thus fluidically connected with the chambers 74 , 75 .

[0200] The plunger 66 thus opens the opening 62 , allowing the lubricating oil to flow from the housing 20 to the oil sump 30 .

[0201] In the event that the lubricating oil pressure in the manifold 26 and chamber 75 drops below a threshold, for example due to a malfunction of the lubrication system 25, the valve 60 automatically moves to the second configuration and the plunger 66 automatically moves to the second position ( Figure 4 ), in which position it closes and seals the opening 62.

[0202] This occurs because the spring force of spring 69 on end 67 exceeds the force exerted by the pressure of the lubricating oil in chamber 75 on flange 77 of plunger 66, pushing plunger 66 to the second position.

[0203] In this case, the flange 77 is interposed axially between the opening 72 and the chambers 74 , 75 along the axis E. The opening 72 is thus fluidically isolated from the chamber 74 .

[0204] At this point, the lubricating oil remains trapped within the housing 20 of the module 11 and defines an oil bath in which the gear 17 is at least partially immersed.

[0205] The operation of the gear 17 sprays the lubricating oil toward the area to be lubricated of the module 11, effectively achieving splash lubrication.

[0206] The pressure sensor 150 detects the pressure at the opening 72 and can continuously monitor whether the valve 60 is in the first configuration or the second configuration.

[0207] Reference Figures 5 to 7 , reference numeral 25 ′ denotes a lubrication system 25 according to another embodiment of the present invention.

[0208] The lubrication system 25 ′ is similar to the lubrication system 25 and only the differences will be described below; where possible, identical or equivalent parts of the lubrication systems 25 , 25 ′ will be indicated by the same reference numerals.

[0209] In particular, lubrication system 25' differs from lubrication system 25 in that it is a dry-sump, forced recirculation lubrication system.

[0210] The lubrication system 25' is also different from the lubrication system 25 in that it comprises:

[0211] a tank 100 ′ common to the modules 11 , 13 , 15 , fluidically isolated from the casings 20 of these modules 11 , 13 , 15 and fluidly interposed between the aforementioned casing 20 and the pump 36 ;

[0212] a plurality of recovery pumps 101 ′ associated with respective stages 11 , 13 , 15 and having respective inlet openings 102 ′ fluidly connected to respective housings 20 and a plurality of discharge openings 103 ′ fluidly connected to tank 100 ′; and

[0213] A fluid line 104 ′ is inserted between the valve 60 ′ of the module 11 and the nozzle 155 ′ of the module 11 .

[0214] In the case shown, the tank 100 ′ is fluidically separated from the housing 20 , in particular arranged outside the housing 20 .

[0215] Alternatively, the tank 100' may be disposed within the housing 20, yet remain fluidly distinct therefrom.

[0216] The lubrication system 25' differs from the lubrication system 25 in that:

[0217] - the valve 60 ′ associated with the module 11 is arranged outside the housing 20 ; and

[0218] The valve 60 ′ of a module 11 is a three-way valve fluidically connected to the exhaust port 103 ′ associated with the same module 11 , to the tank 100 ′ and to the housing 20 .

[0219] In more detail, when it is set to the first configuration ( Figure 6), the valve 60' fluidically connects the discharge port 103' of the recovery pump 101' of the module 11 with the tank 100', and fluidically isolates the discharge port 103' of the module 11 from the fluid pipeline 104'.

[0220] On the contrary, when it is set to the second configuration ( Figure 7 ), the valve 60 ′ fluidly isolates the discharge port 103 ′ of the recovery pump 101 ′ from the tank 100 ′ and fluidly connects the discharge port 103 ′ to the fluid line 104 ′ and thus to the housing 20 .

[0221] Reference Figure 6 and Figure 7 , the valve 60' comprises:

[0222] - housing 110';

[0223] - a plunger 111 ', which is in a first position ( Figure 6 ) and the second position ( Figure 7 ) and

[0224] A spring 112 ′, which is inserted between the housing 110 ′ and the plunger 111 ′ and is designed to elastically push the plunger 111 ′ towards the first position.

[0225] In the case shown, the spring 112 ′ is of the helical type.

[0226] The plunger 111' comprises:

[0227] - two enlarged portions 113 ′, 114 ′ which are axially opposite each other and slide in a sealed manner inside the housing 110 ′; and

[0228] A rod 115 ′ axially connecting the enlargements 113 ′, 114 ′ and having a smaller diameter than the housing 110 ′.

[0229] In particular, the enlarged portion 113' contacts the spring 112'. The enlarged portion 114' and the housing 110' define a chamber 116'. The chamber 116' opens axially on the opposite side of the enlarged portion 114' and is fluidly connected to the manifold 26.

[0230] Therefore, the expanded portion 114 ′ is subjected to the pressure of the lubricating oil in the header 26 .

[0231] The pressure pushes the plunger 111' to the first position ( Figure 6 ).

[0232] In particular, Figure 6 The first position of the plunger 111' causes the spring 112' to be compressed. Figure 7The second position of the middle plunger 111 ′ causes the spring 112 ′ to extend.

[0233] The housing 110 ′ comprises three openings 125 ′, 126 ′, 127 ′ which are through-openings in a radial direction of the axis F and are axially staggered with respect to one another.

[0234] More specifically, opening 125 ′ is fluidly connected to tank 100 ′, opening 126 ′ is fluidly connected to recovery pump 101 ′ and opening 127 ′ is fluidly connected to fluid line 104 ′.

[0235] In the case shown, the opening 126 ′ is diametrically opposed to the openings 125 ′, 127 ′.

[0236] Thus, the plunger 111 ′ is subjected to opposing forces generated by the spring 112 ′ and the lubricating oil pressure in the manifold 26 .

[0237] The dimensions of the valve 60' are such that when the pressure is greater than the threshold value, the force generated on the expansion portion 114 overcomes the elastic effect of the spring 112'. In this case, the expansion portion 114' blocks the opening 127' and the plunger 111' opens the openings 125', 126' ( Figure 6 In this case, the valve 60' is set in the first configuration and the plunger 111' is set in the first position ( Figure 6 ).

[0238] On the contrary, when the pressure of the lubricating oil is less than the threshold value, the elastic effect of the spring 112' exceeds the effect of the lubricating oil pressure on the expansion part 114'. In this case, the expansion part 113' blocks the opening 125' and the plunger 111' opens the openings 126' and 127' ( Figure 7 ). Thus, the valve 60' is set in the second configuration and the plunger 111' is set in the second position ( Figure 7 ).

[0239] In a similar manner to the lubrication system 25 , the lubrication system 25 ′ comprises a pressure sensor 150 ′ designed to detect the pressure within the opening 151 ′ of the housing 110 ′.

[0240] In more detail, the opening 151 ′ is a through opening in a radial direction of the axis F and is axially staggered relative to the openings 125 ′, 126 ′, 127 ′.

[0241] When the valve 60' is set in the second configuration and the plunger 111' is in the second position ( Figure 7 ), the enlarged portion 114 ′ blocks the opening 151 ′.

[0242] Therefore, the pressure sensor 150' detects a pressure value of substantially zero.

[0243] In contrast, when the valve 60' is set in the first configuration and the plunger 111' is in the first position ( Figure 6 ), the enlarged portion 114 ′ opens the opening 127 ′, which is in fluid communication with the chamber 116 ′ and thus with the manifold 26 .

[0244] Therefore, the pressure sensor 150 ′ detects a pressure value substantially equal to the pressure value of the lubricating oil in the header 26 .

[0245] Thus, the pressure readings provided by pressure sensor 150' clearly indicate:

[0246] - the valve 60 ′ is in the second configuration and therefore proposes a rapid landing of the helicopter 1 ; or

[0247] The valve 60 ′ is in the first configuration and the lubrication system 15 operates normally.

[0248] In the case shown, the modules 13 , 15 do not comprise a valve 60 ′.

[0249] The operation of the lubrication system 25 ′ differs from that of the lubrication system 25 in that, when the pressure of the lubrication oil is greater than a threshold value, the recovery pump 101 ′ draws the lubrication oil from the housing 20 and delivers it to the tank 100 ′.

[0250] In this case, the valve 60 ′ is arranged in a first configuration in which it fluidly connects the recovery pump 101 ′ with the tank 100 ′ and fluidly isolates the recovery pump 101 ′ from the fluid line 104 ′.

[0251] More specifically ( Figure 6 ), the pressure of the lubricating oil on the enlarged portion 114' overcomes the elastic effect of the spring 112'.

[0252] Thus, the enlarged portion 114' blocks the opening 127' and the plunger 111' leaves the openings 125', 126' open ( Figure 6 ).

[0253] Conversely, when the pressure of the lubricating oil in the manifold 26 is less than a threshold value, for example due to a malfunction in the lubrication system 25', the valve 60' automatically moves to the second configuration. Figure 7 ), valve 60' fluidly connects recovery pump 101' to fluid line 104' and fluidly isolates recovery pump 101' from tank 100'.

[0254] Therefore, the lubricating oil reaches the nozzle 155', which then sprays it again into the interior of the housing 20, thereby ensuring lubrication of the module 11 even when the pressure of the lubricating oil is less than the threshold value.

[0255] In more detail ( Figure 7 ), the elastic action of the spring 112' overcomes the action of the pressure of the lubricating oil on the expansion part 114'. In this case, the expansion part 113' blocks the opening 125' and the plunger 111' opens the openings 126', 127'.

[0256] The pressure sensor 150 ′ detects the pressure at the opening 151 ′ and is able to continuously monitor whether the valve 60 ′ is in the first configuration or the second configuration.

[0257] From an examination of the characteristics of the helicopter 1 and the lubrication method according to the invention, the advantages that can be obtained thereby are apparent.

[0258] In particular, when the pressure of the lubricating oil in the manifold 26 is greater than / less than a threshold value, the valves 60, 60' of the module 11 are set to the first / second configuration ( Figure 3 , Figure 4 , Figure 6 and Figure 7 ).

[0259] Thus, in the event of a malfunction in the lubrication system 25 , 25 ′ resulting in a drop in lubrication oil pressure, the valves 60 , 60 ′ prevent the lubrication oil from returning to the pump 36 and retain the lubrication oil within the housing 20 .

[0260] In this way, in the event of a malfunction of the lubrication system 25 , 25 ′, the gears 17 contained in the module 11 remain immersed in a bath of lubricating oil and, due to their movement, spray this lubricating oil towards the area to be lubricated.

[0261] In other words, the movement of the valves 60 , 60 ′ to the respective second configuration “seals” the module 11 , preventing the lubricating oil from escaping and effectively achieving splash lubrication of the module 11 .

[0262] Since they are automatic, as soon as the pressure value in the manifold 26 drops below a threshold value, the valves 60 , 60 ′ are moved to the associated second configuration in a repeatable and effective manner and without the need for expensive dedicated controls.

[0263] The sensor 150 is operably connected to the openings 72 and detects pressure values ​​at these openings 72 and provides a signal indicating whether the valve 60 is in the first configuration or the second configuration.

[0264] Similarly, pressure sensor 150' is operably connected to opening 155' of valve 60' and provides a signal indicating whether valve 60' is in the first configuration or the second configuration.

[0265] Thus, when the valve 60, 60' is in the second configuration, the pressure sensor 150, 150' provides a reading that clearly indicates a drop in lubrication oil pressure and a consequent malfunction of the lubrication system 25, 25'.

[0266] This warns the pilot to land quickly.

[0267] In contrast, when the valve 60 ′ is in the first configuration, the pressure sensor 150 ′ provides readings that indicate the pressure within the manifold 26 and that the lubrication system 25 ′ is operating properly.

[0268] Finally, it is obvious that modifications and variations may be made to the helicopter 1 and to the lubrication method described and illustrated herein without departing from the scope defined in the claims.

[0269] In particular, the aircraft 1 ′ may be a thrust-reversed aircraft instead of a helicopter.

[0270] The modules 13, 15 may also comprise valves 60, 60'.

[0271] Finally, the pressure sensors 150, 150' may be replaced by pressure switches designed to generate a first signal upon detecting a pressure greater than a threshold value and a second signal upon detecting a pressure less than the threshold value.

Claims

1. An aircraft with hovering capability, comprising: - a motion transmission unit, which is composed of at least one first module; as well as - a lubrication system designed to lubricate the motion transmission unit; The first modules include: - housing; and - one or more movable members housed within said housing; The lubrication system comprises: - lubrication fluid supply manifold; - at least one nozzle, to which said lubricating fluid from said supply manifold can be fluidly supplied and which is designed to supply said lubricating fluid to the interior of said housing of said first module so as to be able to lubricate said associated movable member; - a collecting tank for the lubricating fluid sprayed by the nozzle; and - a recirculation device designed to recirculate said lubricating fluid from said collection tank to said supply manifold; characterised in that at least the first module comprises a valve which can be used in a first configuration when the pressure of the lubricating fluid in the supply manifold is greater than a threshold value, in which first configuration the lubricating fluid is enabled to flow out of the first module to the recirculation device; The valve is operable in a second configuration when the pressure of the lubrication fluid within the supply manifold is less than the threshold value, in which the valve fluidly isolates the first module from the recirculation device and is capable of retaining the lubrication fluid within the housing.

2. The aircraft according to claim 1, characterized in that The valve is automatic and movement of the valve between the first configuration and the second configuration is automatically determined by the value of the pressure within the supply manifold.

3. The aircraft according to claim 2, characterized in that The valve further comprises: - a housing, which is fixed relative to the casing; - a plunger which slides within the housing between a first position and a second position corresponding to the first configuration and the second configuration, respectively; - elastic means, interposed between said housing and said plunger and designed to elastically urge said plunger towards said second position; and - a chamber defined between the housing and the plunger, fluidly connected to the supply manifold and configured to exert an action on the plunger opposite to the action exerted by the elastic means and directed, in use, to the first position.

4. The aircraft according to claim 3, characterized in that The motion transmission unit includes at least one second module; The supply header is common to the first module and the second module; The collection tank is an oil sump shared between the first module and the second module, the oil sump being defined by the housing of at least one of the first module and the second module and being designed to be filled with the lubricating fluid.

5. The aircraft according to claim 4, characterized in that The housing includes a region for accommodating the valve and a fluid passage fluidly interposed between the region and the collection tank; the at least one nozzle being configured to supply the lubricating fluid in the region; the plunger, when disposed in the first position, causes the fluid passage to be open and allows the lubricating fluid to flow from the housing to the collection tank; The plunger blocks the fluid passage when disposed in the second position and retains the lubricating fluid in the housing during use.

6. The aircraft according to claim 3, characterized in that It comprises a sensor designed to provide an indication associated with whether the valve is in the first configuration or the second configuration.

7. The aircraft according to claim 6, characterized in that The sensor is a pressure sensor or a pressure switch and is configured to provide a signal associated with the pressure of the supply manifold when the valve is in the first configuration.

8. The aircraft according to claim 7, characterized in that The housing includes a first opening operatively connected to the sensor; The sensor is configured to detect pressure within the first opening.

9. The aircraft according to claim 8, characterized in that The first opening is fluidly connected with the chamber when the plunger is in the first position, and the first opening is fluidly connected with the housing when the plunger is in the second position.

10. An aircraft according to any one of claims 1 to 9, characterized in that It includes: - at least one propulsion unit with corresponding output member; as well as - at least one rotor operatively connected to said output member; The rotor includes a main shaft; The motion transmission unit comprises: - a pair of first gearwheels interposed between said output member and at least one intermediate shaft; - at least one pair of second gearwheels interposed between said intermediate shaft and said main shaft; The first module includes the corresponding first gear; The motion transmission unit further comprises a second module accommodating the at least one pair of second gears; The supply header is common to the first module and the second module; and / or Characterized in that it is a helicopter or a thrust-reversed aircraft.

11. A method of lubricating a module of a transmission unit of an aircraft having hovering capabilities, The modules include: -shell; as well as - a movable member housed within said housing; The method comprises the following steps: i) collecting the lubrication fluid in a supply header; ii) supplying the lubricating fluid contained in the supply manifold into the housing to enable lubrication of the movable components of the module; and iii) recirculating the lubrication fluid delivered into the housing to the supply header; It is characterized in that it comprises the following steps: iv) when the pressure of the lubrication fluid within the supply manifold is greater than a threshold, setting a valve of the module to a first configuration in which the valve allows recirculation of the lubrication fluid to the supply manifold; and v) when the pressure of the lubrication fluid within the supply manifold is less than a threshold value, placing the valve into a second configuration in which the valve prevents the recirculation and retains the lubrication fluid within the housing.

12. An aircraft having a hovering capability, comprising: - a motion transmission unit, which is composed of at least one first module; as well as - a lubrication system designed to lubricate the motion transmission unit; The first module further comprises: - housing; and - one or more movable members housed within said housing; The lubrication system comprises: - lubrication fluid supply manifold; - at least one nozzle, to which said lubricating fluid from said supply manifold can be fluidly supplied and which is designed to supply said lubricating fluid to the interior of said housing of said first module so as to be able to lubricate said associated movable member; - a collecting tank for the lubricating fluid sprayed by the nozzle; and - a recirculation device designed to recirculate said lubricating fluid from said collection tank to said supply manifold; at least the first module comprises a valve operable in a first configuration when the pressure of the lubricating fluid in the supply manifold is greater than a threshold value, in which first configuration the lubricating fluid is enabled to flow out of the first module to the recirculation device; the valve being operable in a second configuration when the pressure of the lubrication fluid within the supply manifold is less than the threshold value, in which second configuration the valve fluidically isolates the first module from the recirculation device; The aircraft also includes: a recovery pump having an inlet and an outlet fluidly connected to the housing; the collection tank being fluidly isolated from the housing; and - a fluid line extending between the valve and the housing; The recirculation device includes a transfer pump having an inlet fluidly connected to the collection tank and a discharge port fluidly connected to the supply header; The valve is inserted between the discharge port of the recovery pump and the collection tank; the valve fluidly connects the discharge port of the recovery pump to the collection tank and fluidly isolates the discharge port of the recovery pump from the fluid line when disposed in the first configuration; the valve fluidly connects the exhaust port to the fluid line and fluidly isolates the exhaust port from the collection tank when disposed in the second configuration; Characterized in that the fluid pipeline is directly inserted between the valve and the nozzle of the first module; the valve is automatic and movement of the valve between the first configuration and the second configuration is automatically determined by the value of the pressure within the supply manifold; The valve further comprises: -case; - a plunger which slides within the housing between a first position and a second position corresponding to the first configuration and the second configuration, respectively; - elastic means, interposed between the housing and the plunger and designed to elastically push the plunger towards the second position; and - a chamber defined between said housing and said plunger, fluidly connected to said supply manifold and configured to exert an action on said plunger opposite to that exerted by said elastic means and directed, in use, towards said first position; The valve further comprises: - a first opening fluidly connected to said fluid line; - a second opening fluidly connected to the discharge port of the recovery pump; and - a third opening fluidly connected to the collection tank; When the plunger is disposed in the first position and the valve is disposed in the first configuration, the plunger blocks the first opening and places the second opening and the third opening in fluid communication with each other; When the plunger is disposed in the second position and the valve is disposed in the second configuration, the plunger blocks the third opening and places the first opening and the second opening in fluid communication with each other; The aircraft further includes a sensor designed to provide an indication associated with whether the valve is in the first configuration or the second configuration; The sensor is a pressure sensor or a pressure switch and is configured to provide a signal associated with the pressure of the supply manifold when the valve is in the first configuration; The housing includes a fourth opening operatively connected to the sensor; The sensor is configured to detect pressure within the fourth opening; the plunger obstructing the fourth opening in use when the valve is in the first configuration or the second configuration; The plunger opens the fourth opening and places the fourth opening in fluid communication with the supply manifold when the valve is in the other of the first configuration and the second configuration.

13. The aircraft according to claim 12, characterized in that The valve is disposed outside the first module.

14. An aircraft according to any one of claims 12 and 13, characterized in that It includes: - at least one propulsion unit with corresponding output member; as well as - at least one rotor operatively connected to said output member; The rotor includes a main shaft; The motion transmission unit comprises: - a pair of first gearwheels interposed between said output member and at least one intermediate shaft; - at least one pair of second gearwheels interposed between said intermediate shaft and said main shaft; The first module includes the corresponding first gear; The motion transmission unit further comprises a second module accommodating the at least one pair of second gears; The supply header is common to the first module and the second module; and / or Characterized in that it is a helicopter or a thrust-reversed aircraft.

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