INSULATION OF A HEAT EXCHANGER OF A TURBINE DRIVE IN THE CASE OF A LEAK AT AN ELECTRICAL AND MECHANICAL HYDRAULIC CONTROL VALVE

Description

TECHNICAL FIELD

[0001] The invention relates to the general technical field of aircraft turbomachinery such as turbojets and turboprops. More specifically, it concerns the isolation of a heat exchanger located in a turbomachine stator blade in the event of a leak. PREVIOUS STATE OF THE ART

[0002] Some turbomachines include air / oil heat exchangers to cool the oil through contact with ambient air. These exchangers operate only during certain turbomachine operating modes, to prevent excessive oil cooling in cold flight conditions or to avoid oil retention in turbomachine lubrication chambers during turbomachine cruise.

[0003] Some lubrication systems include a thermostatic valve with low-temperature solid wax to divert lubricant when its temperature drops below a threshold. However, these thermostatic valves cannot completely shut off the oil supply to the heat exchanger, nor can they withstand a high number of open / close cycles.

[0004] Lubrication circuits include a hydraulic valve configured to open when the lubricant pressure differential exceeds a second threshold value, and to divert the lubricant when the lubricant temperature falls below a first threshold value. The circulation of cold lubricant results in greater pressure losses in the hydraulic circuit. However, these hydraulic valves cannot completely shut off the oil supply to the heat exchanger. Furthermore, the operation of these hydraulic valves is unstable, making their use in a lubrication circuit impractical.

[0005] Some of these air / oil heat exchangers are located in stator blade sectors and are arranged in parallel. The oil circulating in each exchanger is cooled by air that comes into contact with the stator blade sector of the turbomachine.

[0006] Such a turbomachine is for example known from application WO 2016 / 156743 of the company Snecma.

[0007] However, the blades of a stator blade sector can be damaged, for example, by impact with a foreign object on the turbomachine, which can lead to relatively significant oil leaks in the heat exchangers housed within these blades. If these leaks continue, the amount of oil escaping from the turbomachine's lubrication circuit can become so great that the insufficient remaining oil supply causes the turbomachine to shut down in flight. Application FR3001253A1 discloses a prior art turbomachine fluid circuit assembly. DESCRIPTION OF THE INVENTION

[0008] The invention aims to solve at least partially the problems encountered in prior art solutions.

[0009] In this regard, the invention relates to a turbomachine fluid circuit assembly. The assembly comprises a main branch which includes a heat exchanger.

[0010] According to the invention, the assembly includes a fluid distributor to the heat exchanger. The fluid distributor comprises a fluid inlet, a main fluid outlet, a fluid bypass outlet, a shutter, an elastic means for actuation of the shutter, and an electrical control means for the shutter.

[0011] The main fluid outlet is fluid-connected to the main branch. The bypass fluid outlet is fluid-connected to a bypass branch arranged parallel to the main branch. The valve is movable between a main open position, in which it closes the bypass outlet and allows fluid to flow in the main branch, and a bypass position, in which it closes the main outlet and allows fluid to flow in the bypass branch.

[0012] The elastic means for actuation of the shutter is configured to move the shutter so that it closes the main outlet when a fluid pressure value is below a first threshold value. The electrical control means for the shutter is configured to move the shutter to the main opening position or the bypass position.

[0013] Thanks to the fluid distributor of the assembly according to the invention, the flow and cooling of the fluid are able to be controlled and adapted according to the operating conditions of the turbomachine, while limiting the impact of leaks in the main branch and facilitating the detection of leaks in the main branch.

[0014] The shutter moves automatically to the bypass position by hydromechanical control, which limits the intervention of a digital turbomachine control system to isolate the heat exchanger in case of heat exchanger leakage.

[0015] Specifically, the fluid pressure in the main branch upstream of the heat exchanger is compared to the first threshold value. This is, for example, the fluid pressure at the inlet of the fluid distributor.

[0016] The invention may optionally include one or more of the following features, combined or not.

[0017] The assembly includes, in particular, a bladed stator section, with the heat exchanger located in the bladed stator section.

[0018] According to one embodiment, the electrical control means of the shutter includes a first electrical control element of the shutter which is configured to move the shutter towards the main opening position, in particular when the fluid pressure value is less than the first threshold value.

[0019] In particular, the first electrical control unit supplies the exchanger with fluid when the turbomachine starts up.

[0020] According to another embodiment, the electrical control means for the shutter includes a second electrical control element for the shutter which is configured to drive the shutter towards the bypass position, particularly when the fluid temperature is below a second threshold value.

[0021] The second electrical control element of the shutter is, for example, configured to stop the fluid supply to the heat exchanger when the fluid pressure exceeds the first threshold value, or when the fluid temperature is abnormally low. Such a situation can occur during the turbomachine's cruising operation.

[0022] According to one embodiment, the fluid distributor comprises a first chamber and a second chamber separated from each other by a valve. The fluid distributor includes a pressurization inlet for supplying fluid to the first chamber. The elastic force-response means includes a return spring configured to force the valve to move to the bypass position against the pressure of the fluid in the first chamber.

[0023] This return spring can be a tension spring located in the first chamber or a compression spring located in the second chamber.

[0024] According to another embodiment, the main branch includes a non-return device which is configured to limit / prevent fluid flow to the heat exchanger when the shutter is in the bypass position.

[0025] Preferably, the non-return device includes a non-return valve.

[0026] According to a particular embodiment, the bypass branch includes a hydraulic resistive element which is designed so that a hydraulic resistance value in the bypass branch is substantially equal to a hydraulic resistance value in the main branch.

[0027] Preferably, the hydraulic resistive element includes a diaphragm.

[0028] According to another embodiment, the fluid distributor shutter is in the main open position when a fluid temperature is above the second threshold value, when a turbomachine shaft rotation value is above a third threshold value, and no fluid leakage is detected in the main branch.

[0029] The rotation value of the turbomachine shaft can determine the fluid pressure of the assembly and be measured independently of the assembly.

[0030] According to another embodiment, the fluid distributor's obturator is in the bypass position when the fluid temperature is strictly below the second threshold value, or when the rotation value of a turbomachine shaft is strictly below the third threshold value, or when a fluid leak is detected in the main branch.

[0031] According to a particular embodiment, the position of the fluid distributor's obturator is controlled by an electrical control in the transient regime of the fluid distributor.

[0032] According to a particular embodiment, the position of the fluid distributor's obturator is controlled by a hydromechanical control in stable regime of the fluid distributor.

[0033] Electrical control of the shutter position helps to limit shutter position instabilities during transient positions of the fluid distributor's shutter. Furthermore, the digital control system is only likely to be activated during normal turbomachine operation to control shutter movement, and only for a short period.

[0034] The hydromechanical control of the shutter position is passive, meaning that it operates automatically without the intervention of an electronic control unit or a digital regulation system.

[0035] According to another embodiment, the fluid distributor includes a safety position in which the shutter is in the bypass position, the shutter being locked in the safety position when the shutter has moved from the main opening position to the bypass position by a hydromechanical control of the shutter.

[0036] According to one embodiment, the assembly includes a leak detector configured to detect a leak in the main branch when the fluid distributor's obturator moves from the main opening position to the bypass position and in the absence of electrical command to move the obturator to the bypass position.

[0037] According to another particular design feature, the assembly includes a bladed stator sector, with the heat exchanger located in the bladed stator sector.

[0038] Preferably, the bladed stator sector includes rectifier blades for a secondary turbomachine flow.

[0039] Preferably, the bladed sector comprises a radially internal platform, a radially external platform and at least one blade that extends between the radially internal platform and the radially external platform.

[0040] The distributor then makes it possible to limit a leak when an external body impacts the turbine blade and when the heat exchanger inside the blade is damaged.

[0041] The invention also relates to a fluid circuit for a turbomachine. The fluid circuit comprises a first turbomachine assembly as defined above and a second assembly as defined above, which is arranged fluidly in parallel with the first assembly.

[0042] According to a particular embodiment, the fluid is a lubricant. The fluid circuit includes a lubricant supply pump and a turbomachine lubrication chamber, each heat transfer unit being fluidly located between the lubricant supply pump and the lubrication chamber.

[0043] The invention also relates to a turbomachine comprising an assembly as defined above or a fluid circuit as defined above. The turbomachine is, in particular, an aircraft turbomachine. The turbomachine is preferably a turbofan engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention will be better understood upon reading the description of exemplary embodiments, given purely for illustrative purposes and in no way limiting, with reference to the attached drawings in which: there figure 1is a partial schematic representation in longitudinal section of an aircraft turbomachine, according to a first preferred embodiment; the figure 2 is a partial schematic representation of a lubrication circuit for the turbomachine according to the first embodiment, at turbomachine start-up; the figure 3 is a partial schematic representation of the lubrication circuit for the turbomachine according to the first embodiment, in a turbomachine lubricant cooling regime; the figure 4a is a partial schematic representation of a heat exchange system in the lubrication circuit during an initial transient regime at turbomachine start-up; the figure 4b is a partial schematic representation of a heat exchange assembly in the lubrication circuit after the turbomachine has started; the figure 4cis a partial schematic representation of a heat exchange system in the lubrication circuit during a second transient regime of the heat exchange system; the figure 4d is a partial schematic representation of a heat exchange assembly in the lubrication circuit during the turbomachine's cruising regime; the figure 4e is a partial schematic representation of a heat exchange assembly of the lubrication circuit during a third transient regime of the heat exchange assembly; the figure 4f is a partial schematic representation of a heat exchange assembly in the lubrication circuit under abnormal pressure drop conditions in the heat exchange assembly; the figure 5is a partial schematic representation of the lubrication circuit for the turbomachine according to the first embodiment, in a regime of abnormal pressure drop in one of the heat exchange units of the lubrication circuit; the figure 6 illustrates a method for controlling the position of the shutter of a fluid distributor in the lubrication circuit based on turbomachine parameters; the figure 7 illustrates a method of controlling the position of the shutter of a fluid distributor in the lubrication circuit from the position of the shutter and a shutter position control. DETAILED DESCRIPTION OF SPECIFIC METHODS OF IMPLEMENTATION

[0045] Identical, similar or equivalent parts of the different figures carry the same numerical references in order to facilitate the transition from one figure to another.

[0046] There figure 1represents a twin-spool, twin-flow turbomachine 1. The turbomachine 1 is a turbojet engine that has a shape of revolution around a longitudinal axis AX.

[0047] The turbomachine 1 includes, in the path of a primary flow 16, an air inlet sleeve 2, a blower 3, a low pressure compressor 4, a high pressure compressor 6, a combustion chamber 7, a high pressure turbine 8 and a low pressure turbine 10.

[0048] A radial direction is a direction orthogonal to the longitudinal axis AX and intersecting with this axis. A circumferential direction is defined as a direction locally orthogonal to a radial direction and to the direction of the longitudinal axis AX.

[0049] In general, the term "air" refers to any gas that can serve as an oxidizer in the turbomachine 1.

[0050] The low pressure compressor 4, the high pressure compressor 6, the high pressure turbine 8 and the low pressure turbine 10 define a secondary flow channel 17 of a secondary flow which bypasses them.

[0051] The high-pressure compressor 6 and the high-pressure turbine 8 are mechanically connected by a drive shaft of the high-pressure compressor 6, so as to form a high-pressure body of the turbomachine 1. Similarly, the low-pressure compressor 4 and the low-pressure turbine 10 are mechanically connected by a shaft of the turbomachine 1, so as to form a low-pressure body of the turbomachine 1.

[0052] The low-pressure compressor 4, the high-pressure compressor 6, the combustion chamber 7, the high-pressure turbine 8 and the low-pressure turbine 10 are surrounded by an internal shroud 9 which extends from the inlet sleeve 2 to the low-pressure turbine 10.

[0053] This internal fairing 9 is surrounded by an external casing 11 which radially delimits the turbomachine outwards with respect to the longitudinal axis AX. The external casing 11 radially delimits outwards the secondary flow 17, particularly at the level of the fan 3.

[0054] The turbomachine 1 comprises at least a first bladed sector 12 and a second bladed sector 12, each extending between the inner shroud 9 and the outer casing 11. The bladed sectors 12 are stator bladed sectors.

[0055] The bladed sectors 12 each comprise a radially internal platform 13, a radially external platform 15 and at least one blade 14 between the radially internal platform 13 and the radially external platform 15.

[0056] The radially internal platform 13 of each bladed sector 12 is rigidly attached to the internal fairing 9. It is radially delimited outwards by a first aerodynamic surface which is in contact with the air of the secondary duct 17.

[0057] The radially external platform 15 of each bladed sector 12 is rigidly attached to the external casing 11. It is radially delimited inwards by a second aerodynamic surface which is in contact with the air of the secondary duct 17.

[0058] The blades 14 of each bladed sector 12 extend radially from the radially internal platform 13 to the radially external platform 15. These blades 14 are spaced from each other in a circumferential direction of the bladed sector 12. In the embodiment shown, each of the blades 14 is a secondary flow straightening blade of the turbomachine.

[0059] A first blade 14 of the first bladed sector 12 houses a first heat exchanger 20a. In the embodiment shown, this first blade 14 also houses a first hydraulic distributor 70a and a first non-return device 30a.

[0060] A second blade 14 of the second bladed sector 12 houses a second heat exchanger 20b. In the embodiment shown, this second blade 14 also houses a second hydraulic distributor 70b and a second non-return device 30b.

[0061] A third blade 14 of one of the bladed sectors 12 houses a third heat exchanger 20c. In the embodiment shown, this third blade 14 also houses a third hydraulic distributor 70c and a third non-return device 30c.

[0062] With reference to the figure 2 and to the figure 3The turbomachine 1 includes a fluid circuit 40. In the embodiment shown, the fluid is a lubricant, typically oil. The fluid circuit 40 is therefore a lubrication circuit.

[0063] The lubrication circuit 40 includes a reservoir 41, a lubricant supply circuit 50, at least one lubrication chamber 43, and a lubricant return circuit 80. The lubrication circuit 40 is configured to circulate lubricant in a closed loop between the supply circuit 50 and the return circuit 80.

[0064] The lubrication chamber 43 is an enclosure within which lubricant is used to lubricate and / or cool components (not shown) of the turbomachine 1, such as shafts and / or bearings. The lubrication chamber 43 is typically a bearing lubrication chamber of the turbomachine 1.

[0065] The lubricant return circuit 80 is configured to circulate lubricant from each lubrication chamber 43 to the reservoir 41. It includes a return pump 82 and a return line 81.

[0066] The return pump 82 is for example a positive displacement or centrifugal pump which is configured to deliver lubricant from the lubrication chamber 43 to the reservoir 41, through the return line 81.

[0067] The lubricant supply circuit 50 comprises, from upstream to downstream, an upstream conduit 51, a supply pump 52, a cooling circuit 54, and a distribution conduit 57.

[0068] In general, upstream and downstream directions are used in this document with reference to the overall overall flow direction of the fluid in the fluid circuit 40.

[0069] The supply pump 52 is for example a positive displacement or centrifugal pump which is configured to deliver lubricant from the reservoir 41 to the lubrication chamber 43, through the upstream conduit 51.

[0070] The upstream conduit 51 comprises one or more conduits. It fluidly connects the reservoir 41 to the cooling circuit 54.

[0071] The distribution conduit 57 comprises one or more conduits. It fluidly connects the cooling circuit 54 to the lubrication chamber 43.

[0072] The cooling circuit 54 comprises a first thermal assembly 60a, a second thermal assembly 60b and at least a third thermal assembly 60c which are arranged in pairs in parallel.

[0073] The first thermal assembly 60a is fluidically connected via a first inlet node A to the upstream conduit 51 and via a first outlet node B to the distribution conduit 57. The second thermal assembly 60b is fluidly connected via a second inlet node C to the upstream conduit 51 and via a second outlet node D to the distribution conduit 57. The third thermal assembly 60c is fluidly connected via a third inlet node F to the upstream conduit 51 and via a third outlet node G to the distribution conduit 57.

[0074] In the embodiment shown, the input nodes A, C, F are substantially coincident and the output nodes B, D, G are substantially coincident.

[0075] In this presentation, the heat exchange assemblies 60 are each of identical structure. Their constituent elements have the same numerical references, with the additional letter a referring specifically to the first heat exchange assembly 60a, with the additional letter b referring specifically to the second heat exchange assembly 60b, and with the additional letter c referring specifically to the third heat exchange assembly 60c.

[0076] Each thermal assembly 60 includes an inlet duct 65, a main branch 62, a bypass branch 64, a hydraulic distributor 70, and an outlet duct 67.

[0077] The inlet duct 65 of each of the thermal units 60 is connected to the upstream duct 51 via its inlet node. The outlet duct 67 of each of the thermal units 60 is connected to the distribution duct 57 via its outlet node. The main branch 62 and the branch 64 are arranged in parallel, each connected to the inlet duct 65 and the outlet duct 67.

[0078] The main branch 62 of each of the thermal assemblies 60 comprises from upstream to downstream one of the heat exchangers 20 and a non-return device 30 which are fluidically connected by a main conduit 61.

[0079] Each of the heat exchangers 20 is configured to cool the lubricant of the main branch 62 by contact with the air which circulates around the stator blades 14 in the secondary vein 17.

[0080] Each check valve 30 includes a check valve in the embodiment shown. The check valve 30 is configured to limit / prevent fluid flow through the heat exchanger 20 when the valve 79 of the hydraulic distributor 70 is in the bypass position to direct the lubricant to the bypass branch 64.

[0081] The branch branch 64 of each of the thermal assemblies 60 comprises a hydraulic resistive element 66 and a branch conduit 63.

[0082] In general, the hydraulic resistive element 66 is designed so that a hydraulic resistance value in the bypass branch 64 is substantially equal to a hydraulic resistance value in the main branch 62.

[0083] In this discussion, the hydraulic resistance of a lubrication circuit element 40 is defined, by analogy with the field of electricity, as the ratio of the pressure drop across that element to the lubricant flow rate through it. By metonymy, and again by analogy with the field of electricity, a hydraulic resistance, or hydraulic resistive element, corresponds to an element of the lubrication circuit 40 characterized by the value of its hydraulic resistance.

[0084] In the embodiment shown, the hydraulic resistive element 66 includes a diaphragm. The lubrication circuit 40 includes a first diaphragm 66a, a second diaphragm 66b, and a third diaphragm 66c.

[0085] Each hydraulic distributor 70 is also referred to as a fluid distributor 70 in this description. It comprises a main lubricant inlet 71, a pressurization inlet 77, a shut-off valve 79, a shut-off control means, a main outlet 73, and a bypass outlet 75.

[0086] The lubricant distributor 70 comprises a first chamber and a second chamber separated from each other by the obturator 79, which is a spool in the illustrated embodiment. The control means includes, in particular, a return spring, which may be a tension spring located in the first chamber and / or a compression spring located in the second chamber, to move the obturator 79 against the pressure of the lubricant in the first chamber.

[0087] The obturator 79 is movable between a main opening position and a bypass position. In the embodiment shown, each hydraulic distributor 70 is bistable. The main opening position is a first stable opening position of the obturator 79, and the bypass position is a second stable opening position of the obturator 79.

[0088] In the main open position, the obturator 79 closes the bypass outlet 75 and allows fluid to flow in the main branch 62 through the main outlet 73. In the bypass position, the obturator 79 closes the main outlet 73 and allows fluid to flow in the bypass branch 64 through the bypass outlet 75.

[0089] The lubricant distributor 70 includes a safety position in which the obturator 79 is locked, when the obturator 79 has moved from the main opening position to the bypass position by a hydromechanical control of the obturator 79. The safety position of the obturator 79 is the bypass position.

[0090] The main inlet 71 of each hydraulic distributor is fluidly connected to the inlet conduit 65 of the corresponding heat exchange assembly 60.

[0091] With joint reference to figures 2 to 5The pressurization inlet 77 is fluidly connected via a pressurization line 69 to the inlet line 65 of the heat exchanger assembly 60. The pressurization inlet 77 is designed to supply fluid to the first chamber of the hydraulic distributor 70. The pressurization line 69 is designed to provide a pressure tap for the lubricant. The lubricant pressure at the pressurization inlet 77 is substantially the same as that at the main inlet 71.

[0092] The main fluid outlet 73 is fluidly connected to the main branch 62 upstream of the heat exchanger 20 and the non-return device 30.

[0093] The bypass outlet 75 of fluid is fluidly connected to the bypass branch 64 upstream of the hydraulic resistive element 66.

[0094] With joint reference to figures 2 to 5, the control means of each shutter 79 includes an electrical control means 72, 74 of the shutter, an elastic stress means 78 of the shutter, and a hydraulic control means 76 of the shutter.

[0095] The elastic means of stressing the obturator 78 and the hydraulic control means of the obturator 76 control the movement of the obturator 79 in stable regime of the hydraulic distributor 70.

[0096] The elastic force-retaining means 78 for the obturator includes the return spring, which is configured to force the obturator 79 to move to the bypass position against the lubricant pressure in the first chamber. It is configured to force the obturator 79 to move to the bypass position when the lubricant pressure at the main inlet 71 is below a first threshold value. In particular, the lubricant pressure is a value corresponding to the fluid pressure in the main branch 62 upstream of the heat exchanger 20.

[0097] The hydraulic control means 76 of the shutter includes the pressurization inlet 77 and the pressurization conduit 69. It is configured to induce the movement of the shutter 79 towards the main opening position when the lubricant pressure at the main inlet 71 is greater than the first threshold value.

[0098] The elastic means of stressing the obturator 78 and the hydraulic control means 76 serve in particular to automatically control the movement of the obturator by a hydromechanical control towards the bypass position in the event of an abnormal drop in pressure in the main branch 62 during the flight of the turbomachine 1.

[0099] The electrical control means 72, 74 of the shutter is configured to control the movement of the shutter 79 to the main opening position or the bypass position. It is configured to control the movement of the shutter 79 in the transient state of the hydraulic distributor 70.

[0100] The transient operating mode of the hydraulic distributor 70 refers to a transient operating phase of the hydraulic distributor 70. In other words, it is an operating phase during which the position of the valve 79 of the hydraulic distributor 70 is not the same as it would be in a steady-state operating mode of the turbomachine. The stable operating mode of the hydraulic distributor 70 refers to a substantially steady-state operating phase of the hydraulic distributor 70. In other words, it is an operating mode of the hydraulic distributor 70 during which the position of the valve 79 of the hydraulic distributor 70 corresponds to the position it would have in a steady-state operating mode of the turbomachine.

[0101] The electrical control means 72, 74 of the shutter comprises a first electrical control element 72 of the shutter and a second electrical control element 74 of the shutter.

[0102] The first electrical control element 72 of the shutter is configured to control the movement of the shutter 79 towards the main opening position against the control of the shutter 79 by the elastic means of stressing the shutter 78, in particular when the lubricant pressure is below the first threshold value.

[0103] The first electrical control element 72 of the shutter is specifically configured to move the shutter 79 towards the main opening position when the lubricant temperature is above a second threshold value and the lubricant pressure is likely to be below the first threshold value.

[0104] The first electrical control element 72 of the shutter is used for example to move the shutter 79 towards the main opening position in a first transient regime 201 of starting the turbomachine 1 or in a third transient regime of conveying the lubricant to the corresponding heat exchanger 20.

[0105] The second electrical control element 74 of the shutter is configured to control the movement of the shutter 79 towards the bypass position against the control of the hydraulic control means 76, in particular when the lubricant temperature is below a second threshold value.

[0106] The second electrical control element 74 of the shutter is configured to stop the lubricant supply to the main branch 62 when the lubricant pressure exceeds the first threshold value and the lubricant temperature falls below the second threshold value. Such a situation can occur during the cruising operation of the turbomachine 1.

[0107] There figure 6 represents a control method 300 of the position of the shutter 79 of each hydraulic distributor 70 from operating parameters of the turbomachine.

[0108] In the embodiment, the lubricant pressure at the main inlet 71 of each hydraulic distributor 70 is greater than the first threshold value when the rotation value XN of a turbomachine shaft is greater than a third threshold value.

[0109] The input parameters 301 taken into account for the control of each hydraulic distributor 70 by the corresponding control means include the temperature T of the lubricant, the rotation value XN of a shaft of the high-pressure body of the turbomachine 1, and the position of the shutter 79 of the hydraulic distributor between its main opening position and its bypass position.

[0110] The control method 300 for the position of the shutter 79 takes into account the absence of leak detection 317 in the main branch 62 of the heat exchange assembly 60, or the detection of a leak 319 in the main branch 62 of the heat exchange assembly 60.

[0111] The control means of each shutter 79 controls the position of the shutter 79 so that it is in the main open position at step 302, when the temperature T of the lubricant is greater than the second threshold value at step 307, and the rotation value XN of the turbomachine shaft is greater than the third threshold value at step 309, and in the absence of leak detection 317 in the main branch 62.

[0112] The control means of each obturator 79 controls the position of each obturator 79 so that it is in the bypass position at step 304, when the temperature T of the lubricant is strictly less than the second threshold value at step 313, or when the value of rotation of the turbomachine shaft is strictly less than the third threshold value 315, or when a lubricant leak is detected in the main branch 62 at the leak detection step 319.

[0113] The method of controlling each shutter 79 of the hydraulic distributor 70 from the operation of the turbomachine 1 is now described with reference to figures 4a to 4f .

[0114] At turbomachine start-up, each hydraulic distributor 70 is in an initial transient start-up regime 201, in which the lubricant pressure at the main inlet 71 is below the first threshold value and the lubricant temperature is above the second threshold value. The lubricant pressure in the supply circuit 50 increases as the rotational speed of the high-pressure body shaft increases. The first electrical control element 72 commands the movement of the obturator 79 from the bypass position to the main open position against the obturator's elastic force-carrying means 78. The electrical control of the obturator 79's position towards the main open position, as indicated by arrow 91, is maintained by the first electrical control element 72 as long as the lubricant pressure is not stably above the first threshold value.

[0115] In a first flight regime with turbomachine cooling, each hydraulic distributor 70 is in a first stable cooling regime 203, in which the lubricant pressure at the main inlet 71 is above the first threshold value and the lubricant temperature is above the second threshold value. The position of the obturator 79 is hydromechanically controlled by the hydraulic control means 76 and the elastic obturator tensioning means 78, as indicated by arrow 93. The obturator 79 is in the main open position, and the lubricant flows through the main branch 62, being cooled in the heat exchanger 20.

[0116] When the turbomachine 1 is at altitude and the lubricant temperature becomes too low to cool the lubricant in the heat exchangers 20, each hydraulic distributor 70 enters a second transient bypass regime 205, in which the lubricant temperature falls below the second threshold value. The second electrical control element 74 commands the movement of the shutter 79 from the main open position to the bypass position against the hydraulic control means 76 of the shutter 79. The electrical control of the shutter 79's position in the bypass position, as indicated by arrow 94, is maintained by the second electrical control element 74 as long as the lubricant pressure is not stably below the first threshold value.

[0117] In a first flight regime with turbomachine cooling, each hydraulic distributor 70 is in a second stable lubricant diversion regime 207, in which the lubricant pressure at the main inlet 71 is below the first threshold value and the lubricant temperature is below the second threshold value. The position of the obturator 79 is controlled hydromechanically, as indicated by arrow 95, by the hydraulic control means 76 and by the elastic obturator tensioning means 78. The obturator 79 is in the bypass position and the lubricant flows in the bypass branch 64 without being cooled in the heat exchanger 20.

[0118] When the turbomachine 1 descends in altitude and the lubricant needs to be cooled in the heat exchangers 20, each hydraulic distributor 70 enters a third transient regime 209 for supplying lubricant to the main branch 62, in which the lubricant temperature rises above the second threshold value. The first electrical control element 72 moves the shutter 79 from the bypass position to the main open position against the elastic tensioning means 78 of the shutter. The electrical control of the shutter 79's position in the main open position, as indicated by arrow 97, is maintained by the first electrical control element 72 as long as the lubricant pressure is not consistently above the first threshold value.

[0119] With more specific reference to the figure 4f and to the figure 5When a leak occurs in the main branch 62 of one of the defective heat exchanger assemblies 60 during steady operation of the turbomachine, and when the obturator 79 is in the main open position, the hydraulic distributor 70 of the defective heat exchanger assembly 60 switches to an emergency bypass mode 211. As the lubricant pressure rapidly drops below the first threshold value, the elastic force-extracting means 78 of the obturator controls the movement of the obturator 79 from the main open position to the bypass position against the hydraulic control means 76, as indicated by arrow 99. The obturator 79 of this hydraulic distributor 70 is then locked in the bypass position, which is the safety position of the obturator 79 until the end of the turbomachine flight 1.The lubricant of this heat exchange assembly 60 circulates entirely in the bypass branch 64 of the heat exchange assembly 60.

[0120] Due to the diaphragm 66 of the bypass branch 64, the pressure and lubricant flow remain unchanged in the heat exchange assemblies which are arranged in parallel with the defective heat exchange assembly 60.

[0121] The leak detection method 400 for each hydraulic distributor 70 valve 79 is now described with joint reference to the figure 2 and to the figure 7 .

[0122] The turbomachine 1 includes a system for controlling the position of each shutter and for leak detection. This system for controlling the position of each shutter 79 comprises sensors 92 and the turbomachine's digital control system 90.

[0123] Sensors 92a, 92b, and 92c are configured to perform a measurement that allows the digital control system 90 to determine the position of each hydraulic distributor valve 79. Each sensor 92a, 92b, and 92c includes, for example, a linear position sensor for each valve, known as the "LVDT" sensor.

[0124] The turbomachine digital control system 90 is also known as "FADEC". It comprises a redundant, fully authority, two-channel digital computer. It is configured to determine the position of each shutter 79 from measurements taken by sensors 92 and to implement the leak detection method 400.

[0125] The leak detection process 400 includes determining the position of each shutter 79 in step 401, in particular by the digital control system 90 from the measurements taken by the sensors 92a, 92b, 92c.

[0126] The leak detection method 400 includes a step 403 of verifying the presence of an electrical command to move each shutter 79 to its bypass position, by the second electrical control element 74 of the shutter.

[0127] The leak detection method 400 includes verifying a position displacement of each shutter 79 from its main opening position to its bypass position, in step 405.

[0128] When a shutter 79 has moved from its main opening position to its bypass position following an electrical command to move the shutter 79 to its bypass position, the leak detection method 400 detects an absence of leakage in the main branch 62 of the corresponding heat exchange assembly 60, at step 402.

[0129] When a shutter 79 has moved from its main opening position to its bypass position in the absence of electrical command to move the shutter 79 to its bypass position, the leak detection method 400 detects a leak in the main branch 62 of the corresponding heat exchange assembly 60, at step 404.

[0130] Thanks to the hydraulic distributor 70 of each thermal assembly 60 according to the invention, the flow and cooling of the lubricant are able to be controlled and adapted according to the operating conditions of the turbomachine 1, while limiting the impact of leaks in the main branch 62 and facilitating the detection of leaks in the main branch 62.

[0131] The obturator 79 of each hydraulic distributor 70 moves in particular automatically to the bypass position by a hydromechanical control, which limits the intervention of the digital control system 90 of turbomachine to isolate the heat exchanger 20 in case of leakage of the heat exchanger 20.

[0132] Of course, various modifications can be made by a person skilled in the art to the invention just described without going out of scope of the disclosure of the invention.

[0133] Alternatively, turbomachine 1 is a turbomotor or a turboprop.

[0134] Alternatively, the fluid is fuel. The fluid circuit 40 is then a fuel circuit for turbomachine 1.

[0135] Each of the main branches 62 and each of the branch branches 64 has a variable structure. In particular, the arrangement, number and nature of the hydraulic resistive elements in the lubrication circuit 40 can vary.

[0136] The structure of each of the hydraulic resistive elements 66 of the lubrication system may vary. For example, each of these hydraulic resistive elements 66 may include a heat exchanger, a filter, a shut-off valve and / or a flow meter.

[0137] The number of heat exchangers 20 in each main branch 62 may vary. Each main branch 62 may include at least one filter or other type of hydraulic resistive element.

[0138] Each branch branch 64 may include at least one heat exchanger.

[0139] Alternatively, the supply circuit 50 may include at least two sets of heat exchangers 60 which are arranged in series.

[0140] The structure of each hydraulic distributor 70 may vary, in particular as long as each hydraulic distributor 70 allows lubricant to flow in the main branch 62 at least for certain operating regimes of the turbomachine 1, and directs the lubricant to the bypass branch 64 in other operating regimes of the turbomachine 1 and in case of leakage.

[0141] Alternatively, at least one of the hydraulic distributors 70 is pneumatically controlled at least in stable operating conditions of the turbomachine.

[0142] Alternatively, at least one of the hydraulic distributors 70 includes at least one stable opening position between the main opening position and the bypass position, in which the shutter 79 of the hydraulic distributor partially supplies the corresponding main branch 62 and partially the corresponding bypass branch 64.

[0143] At least one of the hydraulic distributors 70 may include a plurality of stable opening positions between the main opening position and the bypass position, for example a continuity of stable opening positions or a sequence of discrete stable opening positions.

[0144] More generally, each hydraulic distributor 70 can be a different type of distributor than a three-way, two-position hydraulic distributor.

[0145] Alternatively, the obturator 79 of each hydraulic distributor may include a valve instead of a spool.

[0146] Hydraulic distributors 70 can have different structures from each other.

[0147] According to one embodiment, the position monitoring device of each shutter is configured, for example, to determine a lubricant pressure in the main branch 62, for example by means of a first pressure sensor 92, and to determine a lubricant pressure in the bypass branch 64, for example by means of a second pressure sensor 92. The monitoring device can monitor the position of the shutter 79 by comparing the lubricant pressure value in the main branch 62 and the lubricant pressure value in the bypass branch 64.

Claims

1. An assembly (60) for a fluid circuit (40) of a turbine engine (1), comprising: a main branch (62) comprising a heat exchanger (20), a bypass branch (64) which is arranged parallel to the main branch (62), a control valve (70) of fluid to the heat exchanger (20), the fluid control valve (70) comprising: a fluid inlet (71), a main fluid outlet (73) which is fluidly connected to the main branch (62), a fluid bypass outlet (75) which is fluidly connected to the bypass branch (64), a shutter (79) which is movable between a main open position in which it closes the bypass outlet (75) and it allows circulating the fluid in the main branch (62), and a bypass position in which it closes the main outlet (73) and it allows circulating the fluid in the bypass branch (64), the assembly being characterized in that the control valve (70) comprises : resilient means (78) for biasing the shutter which is configured to bias the displacement of the shutter (79) so that it closes the main outlet (73) when a fluid pressure value is lower than a first threshold value, and means (72, 74) for electrically controlling the shutter configured to bias the displacement of the shutter (79) to the main open position or the bypass position.

2. The assembly (60) for a turbine engine (1) according to the preceding claim, wherein the means (72, 74) for electrically controlling the shutter comprises a first member (72) for electrically controlling the shutter which is configured to bias the shutter (79) to the main open position, in particular when the pressure value of the fluid is lower than the first threshold value.

3. The assembly (60) for a turbine engine (1) according to any one of the preceding claims, wherein the means (72, 74) for electrically controlling the shutter comprises a second member (74) for electrically controlling the shutter which is configured to bias the shutter (79) towards the bypass position, in particular when the fluid temperature is lower than a second threshold value.

4. The assembly (60) for a turbine engine (1) according to any one of the preceding claims, wherein the fluid control valve (70) comprises a first chamber and a second chamber which are separated from each other by the shutter (79), the fluid control valve (70) comprising a pressurisation inlet (77) for bringing the fluid into the first chamber, the resilient biasing means (78) comprising a return spring which is configured to bias the displacement of the shutter (79) to the bypass position against the pressure of the fluid in the first chamber.

5. The assembly (60) for a turbine engine (1) according to any one of the preceding claims, wherein the main branch (62) comprises a check device (30) which is configured to limit / prevent the circulation of fluid to the heat exchanger (20) when the shutter (79) is in the bypass position, the check device (30) preferably comprising a check valve.

6. The assembly (60) for a turbine engine (1) according to any one of the preceding claims, wherein the bypass branch (64) comprises a hydraulic resistive element (66) which is designed so that a hydraulic resistance value in the bypass branch (64) is substantially equal to a hydraulic resistance value in the main branch (62), the hydraulic resistive element (66) preferably comprising a diaphragm.

7. The assembly (60) for a turbine engine (1) according to any one of the claims 3-6, wherein the shutter (79) of the fluid control valve is in the main open position when a temperature of the fluid is greater than the second threshold value, when a value of rotation of a turbine engine shaft is greater than a third threshold value, and no fluid leak is detected in the main branch (62), and / or wherein the shutter (79) of the fluid control valve is in the bypass position when the temperature of the fluid is strictly lower than the second threshold value, or when the value of rotation of a turbine engine shaft is strictly lower than the third threshold value, or when a fluid leak is detected in the main branch (62).

8. The assembly (60) for a turbine engine (1) according to any one of the preceding claims, wherein the position of the shutter (79) of the fluid control valve is controlled by an electrical control in transient state of the fluid control valve (70), the position of the shutter (79) of the fluid control valve being in particular controlled by a mechanical hydraulic control in steady state of the fluid control valve (70).

9. The assembly (60) for a turbine engine (1) according to any one of the preceding claims, wherein the fluid control valve (70) comprises a safety position in which the shutter (79) is in the bypass position, the shutter (79) being blocked in the safety position when the shutter (79) is displaced from the main open position to the bypass position by a mechanical hydraulic control of the shutter (79).

10. The assembly (60) for a turbine engine (1) according to any one of the preceding claims, comprising a leak detector (90) configured to detect a leak in the main branch (62) when the shutter (79) of the fluid control valve has been displaced from the main open position to the bypass position in the absence of electrical control of displacement of the shutter (79) to the bypass position.

11. The assembly (60) for a turbine engine (1) according to any one of the preceding claims, comprising a bladed stator sector (12), the heat exchanger (20) being located in the bladed stator sector (12), the bladed stator sector (12) preferably including blades (14) for straightening a secondary flow of a turbine engine (1), the bladed sector (12) preferably comprising a radially inner platform (13), a radially outer platform (15) and at least one vane which extends between the radially inner platform (13) and the radially outer platform (15).

12. A fluid circuit (40) for a turbine engine (1), comprising a first assembly (60a) according to any one of the preceding claims and a second assembly (60b) according to any one of the preceding claims, wherein the second assembly (60b) is arranged fluidly in parallel with the first assembly (60a).