Device for controlling an airflow guidance system, in particular in an aircraft turbomachine

Abstract

The invention relates to a control device (30) for controlling an airflow guiding system (20), comprising: - at least one vane (21) that is rotatable on a shaft (21a) of the vane between a first angle and a second angle; - an actuator (31) comprising a body (32) inside which a piston (32a) is translatably mounted, the piston being rigidly connected to a drive rod (33); - a control rod (34) comprising a downstream end (34a) that is connected to the shaft (21a) of the vane, the actuator (31) being configured to drive the piston (32a) between a first end position (P1') and a second end position (P2') of a nominal operating range and the downstream end (34a) of the control rod (34) between a first end position (P1) and a second end position (P2) of a nominal operating range in which the vane (21) is movable between a first angle and a second angle, the device being characterised in that it comprises a drive mechanism (40) that connects an upstream end (33a) of the drive rod (33) to an upstream end (34b) of the control rod (34), which is opposite the downstream end (34a), and in that the drive mechanism (40) is configured so that, in the event of the control device failing, it places the downstream end (34a) of the control rod (34) in a safety position (PS) located between the first end position (P1) and a second end position (P2) of the nominal operating range and in which the vane (21) is oriented at a safety pitch angle between the first angle and the second angle.

Description

Technical field of the invention

[0001] The present invention relates to the field of aircraft, and in particular to a device for controlling an airflow guidance system, an aircraft turbomachine comprising such a device and a single-engine helicopter comprising such a turbomachine.

[0002] More particularly, the invention relates to controlling the position of air flow guide elements. State of the prior art

[0003] Generally speaking, a turbomachine comprises a compressor, a combustion chamber located at the outlet of said compressor, a high-pressure turbine intended to drive the compressor in rotation and a low-pressure turbine intended to drive the blades of the aircraft in rotation.

[0004] The turbomachine further comprises an airflow guidance system, called "inlet guide vanes", with the acronym "IGV" in English terms, comprising a plurality of variable-pitch inlet guide vanes or blades, positioned upstream of the compressor and making it possible to improve the efficiency of the compressor, and thus the thermodynamic cycle of the engine in cruising mode. Such a system contributes to reducing the aircraft's fuel consumption.

[0005] By "variable timing" we mean the synchronization of the angular position of all the blades of the same stage by means of a control ring or crown secured to all the blades. Each blade is connected to the control ring by a control rod.

[0006] It is known to control the position of the blades by a cylinder system fixed on a casing and comprising a piston movable in a cylinder chamber between two extreme positions of a nominal operating range of the engine, the piston being connected to the control ring by a control rod. During the movement of the piston between the first extreme position and the second extreme position, the blades are continuously movable between a first angle and a second angle.

[0007] The piston movement control is generally carried out by a fluid distributor, for example oil in the case of hydraulic control.

[0008] Document FR 3 051 830 discloses a device for controlling an air flow guidance system comprising at least one blade that can rotate about an axis of the blade between a first angle and a second angle, an actuator comprising a body inside which a piston is mounted in translation, and a control rod comprising a downstream end connected to a control ring, the actuator being configured to drive the piston in movement between a first extreme position and a second extreme position of a nominal operating range and the downstream end of the control rod between a first extreme position and a second extreme position of a nominal operating range in which the blade is movable between a first angle and a second angle.

[0009] US 3,334,521 discloses a control mechanism comprising a lever which is moved in a cam by a piston rod of a hydraulic actuator, providing movement of variable pitch vanes against aerodynamic loads between a normal operating position (vanes open) and an emergency non-operating position (vanes closed).

[0010] Document WO2022 / 101260 (prior art referred to in Art. 54(3) EPC) discloses a device for controlling an air flow guidance system comprising an actuator configured to drive a control rod in translation between a first and a second extreme position of a nominal operating range in which a blade of the flow guidance system is movable between a first and a second angle, the control rod being connected to the blade by a control lever comprising a first control rod and a second control rod articulated relative to each other. The actuator is configured to bring the control rod into a safety position located beyond the second extreme position of the nominal operating range and orient the blade by a safety pitch angle between the first angle and the second angle.

[0011] If a component of the blade control kinematics fails, the position of the piston and thus the blade pitch angle may no longer be known.

[0012] Patent application FR2011526 of November 10, 2020 proposes to modify the kinematics of the blade control in order to reach a safety position located beyond an extreme position of the nominal operating range and to orient the blade at a safe pitch angle located within the nominal operating range.

[0013] However, if the blade control system required maintenance, it would be necessary to return the entire engine for maintenance, which would greatly increase the cost per flight hour of the engine.

[0014] There is a need to know the position of the piston and thus the pitch angle of the blades, at any time, and in a reliable manner, without impacting the maintenance cost of the engine. Statement of the invention

[0015] The present invention therefore aims to overcome the drawbacks of the control devices of the aforementioned air flow guidance systems.

[0016] The aim of the invention is to improve safety in the event of failure of an element of the blade control kinematics and to reduce maintenance costs in the event of failure of the control device.

[0017] The subject of the invention is a device for controlling an air flow guidance system according to claim 1. This control device comprises: at least one blade mobile in rotation around an axis of the blade between a first angle and a second angle, an actuator comprising a body inside which is mounted in translation a piston secured to an actuating rod, and a control rod mounted in translation in the actuating rod and comprising a downstream end connected to the axis of the blade.

[0018] The actuator is configured to move the piston between a first extreme position and a second extreme position of a nominal operating range in which the blade is movable between a first angle and a second angle.

[0019] The actuator is also configured to cause the downstream end of the control rod to move between a first extreme position and a second extreme position of the nominal operating range.

[0020] The control device comprises a drive mechanism connecting an upstream end of the actuating rod to an upstream end of the control rod, opposite the downstream end.

[0021] The drive mechanism is configured to, in the event of a failure of the control device, bring the downstream end of the control rod into a safety position located between the first extreme position and a second extreme position of the nominal operating range and in which the blade is oriented at a safe setting angle between the first angle and the second angle. In the event of a failure of the control device, the actuator is configured to overtravel the piston into a safety position located beyond said second extreme position of the piston in which the blade is oriented at a safe setting angle between the first angle and the second angle.

[0022] The overtravel of the piston ensures that the downstream end of the control rod moves to a safety position.

[0023] The drive mechanism is thus integrated directly between the connection of the control rod and the actuating rod, which improves its accessibility in the event of maintenance.

[0024] Advantageously, the drive mechanism comprises a first connecting member comprising a first end secured to the upstream end of the actuating rod and a second end connected to the control rod via a second connecting member.

[0025] For example, the second connecting member comprises a first end articulated relative to the second upstream free end of the control rod, and a second end articulated relative to the second end of the first connecting member.

[0026] The drive mechanism may further comprise a guide casing fixed to the body of the jack and comprising at least one guide rail cooperating with at least one guide pin carried by the second connecting member.

[0027] Alternatively, two guide rails could be provided cooperating with one or two guide pins carried by the second connecting member.

[0028] Advantageously, the guide rail comprises a rectilinear main portion, substantially parallel to the axis of the turbomachine and a curved end portion, said guide pin being in a collection position inside said end portion in the safety position of the control rod.

[0029] Thus, during normal operation of the compressor, the cylinder rod and thus the control rod is movable in translation in the cylinder chamber between the two extreme positions of the nominal operating range of the turbomachine.

[0030] According to one embodiment, the guide casing comprises two opposite guide rails each cooperating with a bearing carried by the second connecting member.

[0031] The use of bearings makes it possible to improve reliability, and in particular to limit wear and tear in the movement of said second connecting member.

[0032] According to one embodiment, the second end of the control rod articulated relative to the first end of the second connecting member is located upstream of the end of the actuating rod secured to the first connecting member.

[0033] In other words, the attachment of the first connecting member to the actuating rod is located downstream of the upstream end of the control rod.

[0034] According to one embodiment, the second upstream end of the control rod articulated relative to the first end of the second connecting member is located downstream of the upstream end of the actuating rod secured to the first connecting member.

[0035] In other words, the attachment of the first connecting member to the actuating rod is located upstream of the upstream end of the control rod.

[0036] For example, the actuating rod is tubular and is axially traversed by the control rod, the latter being configured to be able to move inside the actuating rod.

[0037] According to another aspect, the invention relates to an aircraft turbomachine comprising, from upstream to downstream in the direction of flow of the air flow, an inlet sleeve receiving air, a centrifugal compressor, an annular combustion chamber, located downstream of the compressor, a high-pressure power turbine intended to rotate the compressor, an outlet turbine intended to rotate an output shaft, an air flow guidance system positioned upstream of the compressor and a device for controlling said air flow guidance system as described previously.

[0038] According to another aspect, the invention relates to a single-engine helicopter comprising a turbomachine as defined above. Brief description of the drawings

[0039] Other objects, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the indexed drawings in which: Other objects, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the indexed drawings in which: [ Fig 1 ] very schematically illustrates a sectional view of an aircraft turbomachine comprising a device for controlling an air flow guidance system according to the invention; [ Fig 2 ] represents the control device of the figure 1 ; [ Fig 3A ], [ Fig 3B ], [ Fig 3C ] schematically represent three positions of the control device and the main vane of the flow guidance system of the figure 2 ; [ Fig 4A ], [ Fig 4B ], [ Fig 4C] schematically represent three positions of a control device according to another embodiment of the invention; and [ Fig 5 ] represents the control device according to another embodiment of the invention. Detailed description of at least one embodiment

[0040] In the remainder of the description, the terms “upstream” and “downstream” are defined in relation to the direction of air flow in the turbomachine.

[0041] On the figure 1 is shown very schematically an axial section of a turbomachine 10, with central axis XX' which corresponds to the axis of a power shaft (or low pressure shaft) of the turbomachine. The turbomachine can equip, by way of non-limiting example, single-engine helicopters.

[0042] The turbomachine 10 comprises, from upstream to downstream in the direction of flow of the air flow, an inlet sleeve 11 receiving air, a centrifugal compressor 12, for example with one or two stages, configured to suck in the air flow F. The turbomachine 10 further comprises an annular combustion chamber 13, for example with reverse flow, located downstream of the compressor 12, a high-pressure power turbine 14 intended to rotate the compressor 12 by a high-pressure shaft 15 and an outlet turbine 16, for example, with a single stage, intended to rotate an outlet shaft 17 by means of a low-pressure shaft 18, coaxial with the high-pressure shaft 15, and a reduction system 19.

[0043] The output shaft 17 is connected to the blades of the aircraft.

[0044] The turbomachine 10 further comprises an air flow guidance system 20, called “inlet guide vanes”, with the acronym “IGV” in English terms, comprising a plurality of variable-pitch guide vanes or blades 21, positioned upstream of the compressor 12.

[0045] In a known manner, for example using a synchronization ring connected to levers for controlling the pitch of all the blades 21, the plurality of variable-pitch blades 21 comprises a main blade controlled in rotation around its axis 21a, and a plurality of secondary blades whose movement is synchronized with the movement of the main blade.

[0046] The blading consisting of the blades 21 is called “stator”, that is to say that each blade is mobile in rotation around its own axis of rotation.

[0047] The axis of rotation 21a of each blade 21 is here perpendicular to the central axis XX' of the turbomachine 10.

[0048] The turbomachine 10 further comprises a device 30 for controlling the air flow guidance system 20.

[0049] The control device 30 of the airflow system 20 comprises an actuator 31 and a control rod 34 connected by its first end 34a to a control lever 35 of a main blade of the plurality of variable-pitch blades 21.

[0050] By "variable pitch" blades we mean the synchronization of the position of all the secondary blades relative to a main blade.

[0051] The control rod 34 is driven in translation by said actuator 31 via a drive mechanism 40.

[0052] The actuator 31 may be, in a non-limiting manner, a jack comprising a body 32 fixed to a casing (not referenced) and delimiting a cylindrical chamber 32a inside which is mounted in translation a piston 32a secured to a tubular jack rod 33 or actuating rod.

[0053] The tubular cylinder rod 33 comprises an upstream end 33a connected to a second upstream end 34b of the control rod 34, opposite the first downstream end 34a connected to the blade 21, via the drive mechanism 40.

[0054] The control rod 34 is mounted in translation in the tubular cylinder rod 33.

[0055] The control rod 34 is connected to the axis of the main blade 21 by the control lever 35 articulated relative to the first free end 34a of the control rod 34 opposite the end 34b connected to the actuator 31. The control lever 35 will not be described further in the remainder of the description.

[0056] The body 32 of the cylinder may comprise two orifices (not shown) opening into the chamber for the entry and exit of a fluid, intended to slide the piston inside said cylinder body along an axis of movement substantially parallel to the central axis XX' of the turbomachine 10.

[0057] For example, the cylinder chamber is supplied with fluid, for example oil, by an external energy source conveying the fluid into the cylinder chamber via the first port. Under the effect of the pressure exerted by the fluid on the rear face of the piston, the latter moves axially along the displacement axis X-X', together with the control rod 34.

[0058] The external energy source can be a hydraulic control system including a distributor or servo valve configured to distribute the fluid in the cylinder chamber. Depending on the servo valve, it is possible to know the piston stroke.

[0059] The piston of the cylinder 32a, and thus the control rod 34, is movable in translation in the chamber of the cylinder between two extreme positions P1', P2'; P1, P2 of a nominal operating range of the turbomachine. During the movement of the cylinder rod 33 between the first extreme position P1' and the second extreme position P2', the main blade 21 is movable continuously between a first angle and a second angle defined respectively between the main blade 21 and the horizontal axis parallel to the axis of movement X-X'.

[0060] The control device 30 is configured to guide the piston 33, and thus the control rod 34, to a safety position PS', PS in which the stroke of the piston is known, and thus the opening angle of the blades 21.

[0061] The safety position PS', PS corresponds to an opening position of the blades in which the turbomachine can operate safely. The main blade 21a is moved to a safe angle between the first and second angles of nominal operation.

[0062] The safety position P'S of the cylinder rod 33 is far from one of the positions P1' , P2' of the nominal operating range.

[0063] The cylinder rod 33 is configured to perform an overtravel beyond one of its extreme positions P2'.

[0064] As illustrated on the figure 2 , the drive mechanism 40 comprises a first connecting member 42 comprising a first end 42a secured to the upstream end 33a of the tubular cylinder rod 33 and a second end 42b connected to the control rod 34 via a second connecting member 44.

[0065] The second connecting member 44 or connecting rod comprises a first end 44a articulated relative to the second free end 34b of the control rod 34, and a second end 44b articulated relative to the second end 42b of the first connecting member 42.

[0066] The first and second connecting members 42, 44 are two separate parts connected to each other by a pivot connection.

[0067] As illustrated on the figure 2 , the second end 34b of the control rod 34 articulated relative to the first end 44a of the second connecting member 44 is located upstream of the end 33a of the tubular cylinder rod 33 secured to the first connecting member 42. In other words, the attachment of the first connecting member 42 to the tubular cylinder rod 33 is located downstream of the upstream end 34b of the control rod 34.

[0068] As illustrated on the figure 2, the drive mechanism 40 further comprises a guide casing 46 fixed to the body 32 of the jack and comprising a guide rail 47 cooperating with a guide pin 44c carried by the second guide member 44. As a variant, two guide rails could be provided cooperating with one or two guide pins carried by the second connecting member 44.

[0069] The guide rail 47 comprises a rectilinear main portion 47a, substantially parallel to the axis XX' of the turbomachine and an end portion 47b at one end of said rail.

[0070] The end portion 47b here has a curved shape.

[0071] Thus, during normal operation of the compressor, the cylinder rod 33 and thus the control rod 34 is movable in translation in the cylinder chamber between the two extreme positions P1', P2'; P1, P2 of the nominal operating range of the turbomachine.

[0072] The extreme position P1', P2' of the cylinder rod 33 is defined by the cylinder. Indeed, in a manner known per se, any cylinder has internal stops which define the stroke of the piston in the body of the cylinder. Thus, the end portion 47b does not serve as a stop before a stop of the cylinder, at the risk of damaging an element of the drive mechanism 40.

[0073] The drive mechanism 40 is configured to bring the control rod 34 into a safety position PS in the event of a failure of the control device 30. The safety position PS of the control rod 34 is located between the two extreme positions P1, P2 of the control rod 34 in nominal operation. The guide pin 44c is in a collection position inside said end portion 47b in the safety position PS of the control rod 34.

[0074] The drive mechanism 40 is integrated directly between the control rod connection and the cylinder rod, which improves its accessibility in the event of maintenance.

[0075] The control rod 34 is configured to move in translation along the axis of movement XX' and along an axis perpendicular to said axis of movement XX' during the movement of the cylinder rod 33. Thus, the control rod 34 has two degrees of freedom.

[0076] The movement of the control rod 34 is illustrated in the Figures 3A, 3B and 3C .

[0077] There Figure 3Arepresents the first extreme position P1 of the free end of the control rod 34 when the cylinder rod 33 is in the first extreme position P1' of the nominal operating range of the turbomachine 10. In the first extreme position P1 of the control rod 34, the main blade 21 is open by a first angle (not shown), for example between 45° and 75°, for example greater than or equal to 60°.

[0078] There Figure 3B represents the second extreme position P2 of the free end of the control rod 34 when the cylinder rod 33 is in the second extreme position P2' of the nominal operating range of the turbomachine 10.

[0079] When moving the cylinder rod 33 from the first extreme position P1' to the second extreme position P2' of the nominal operating range, the drive mechanism 40 is guided in translation in the guide rail 47, in particular on its main portion 47a.

[0080] When moving the control rod 34 from the first extreme position P1 to the second extreme position P2, the main blade 21 is progressively movable from the first angle to a second angle (not shown) for example equal to 0°. The flow rate is maximum in this second extreme position P2.

[0081] There Figure 3C represents the safety position PS of the free end of the control rod 34 when the cylinder rod 33 overtravels or extends beyond the second extreme position P2 of the nominal operating range of the turbomachine 10.

[0082] When the cylinder rod 33 moves from the first extreme position P1' to the second extreme position P2' of the nominal operating range, the drive mechanism 40 is guided in translation in the guide rail 47 towards the end portion 47b. The second connecting member 44 then performs a rotational movement around its second end 44a articulated relative to the upstream end 34b of the control rod 34. It is the overtravel of the cylinder 32a which ensures the movement of the control rod 34 into the safety position.

[0083] When moving the control rod 34 from the second extreme position P2 to the safety position PS, the main blade 21 is progressively movable from the second angle to a safety setting angle between the first and second end angles of the nominal operating range, for example between 5° and 15°, for example equal to 8°. The safety setting angle is linked to the safety position PS' defined by the overtravel of the cylinder rod 33. For example, by means of an extension of the end portion 47b of the guide rail 47 to allow an additional movement of the guide pin 44c and therefore an additional pivoting of the second connecting member 44, an additional overtravel of the cylinder rod 33 would also allow an overtravel of the control rod 34 in the opposite direction so as to move the safety position PS.This would bring the safe setting angle back to a value closer to the first end angle of the nominal operating range.

[0084] Thus, in the event of a failure of an element of the blade control kinematics, bringing the actuator rod 33 into a known safety position, and thus tilting the blades at a known safety angle, makes it possible to know at any time the position of the control rod 34 and therefore the inclination (the pitch angle) of the blades 21, and this reliably without impacting the maintenance cost of the engine. Furthermore, the safety position makes it possible to ensure the operation of the turbomachine, even in the event of a failure of an element of the blade control kinematics.

[0085] The embodiment illustrated on the Figures 4A, 4B and 4C in which the same elements bear the same references, differs from the embodiment illustrated on the figures 2 , 3A, B, 3C only by the fact that the attachment of the first connecting member 42 to the tubular cylinder rod 33 is located upstream of the upstream end 34b of the control rod 34.

[0086] In other words, the second upstream end 34b of the control rod 34 articulated relative to the first end 44a of the second connecting member 44 is located downstream of the upstream end 33a of the tubular cylinder rod 33 secured to the first connecting member 42.

[0087] In the embodiment illustrated in the Figure 5 , in which the same elements bear the same references, the movement of the second connecting member 44 in the nominal operating range is ensured by bearings 50 guided by rails 47, 48 arranged on either side of a double slide.

[0088] The use of bearings makes it possible to improve reliability, and in particular to limit wear of the movement of said second connecting member 44.

[0089] Generally, the use of the control device 30 is not limited to a turbomachine and can be used to ensure the movement of the control rod and thus the orientation of vanes mounted upstream of a steerable wheel towards a safety position in the event of failure of an element of said control device. The safe setting angle of the vanes is included in the setting angle range useful for the nominal operation of the steerable wheel. This safe setting angle is reached during an overtravel of an actuator rod or cylinder of the control device.

[0090] Thanks to the invention, it is possible to bring the control rod and thus the blade pitch angle to a reliable safety position, while facilitating maintenance in the event of failure of the drive mechanism. Indeed, the drive mechanism 40 is integrated directly between the connection of the control rod and the cylinder rod, which improves its accessibility in the event of maintenance.

Claims

1. Device (30) for controlling an air flow guide system (20) comprising: - at least one vane (21) movable in rotation about an axis (21a) of the vane between a first angle and a second angle, - an actuator (31) comprising a body (32) inside which a piston (32a) secured to an actuation rod (33) is translationally mounted, - a control rod (34) translationally mounted in the actuation rod (33) and comprising a downstream end (34a) connected to the axis (21a) of the vane, the actuator (31) being configured to movably drive the piston (32a) between a first end position (P1') and a second end position (P2') of a nominal operating range and the downstream end (34a) of the control rod (34) between a first end position (P1) and a second end position (P2) of a nominal operating range in which the vane (21) is movable between a first angle and a second angle, the device comprising a drive mechanism (40) connecting an upstream end (33a) of the actuation rod (33) to an upstream end (34b) of the control rod (34), opposite to the downstream end (34a), the actuator (31) being configured, in the event of failure of the control device, to overtravel the piston (32a) in a safe position (PS') located beyond the second end position (P2') of the piston and, during the overtravel of the piston (32a) in the safe position (PS'), the drive mechanism (40) being configured to bring the downstream end (34a) of the control rod (34) into a safe position (PS) located between the first end position (P1) and a second end position (P2) of the nominal operating range and in which the vane (21) is oriented at a safe pitch angle between the first angle and second angle.

2. Device (30) according to claim 1, wherein the drive mechanism (40) comprises a first connecting member (42) comprising a first end (42a) integral with the upstream end (33a) of the actuation rod (33) and a second end (42b) connected to the control rod (34) via a second connecting member (44).

3. Device (30) according to claim 2, wherein the second connecting member (44) comprises a first end (44a) hinged relative to the second upstream free end (34b) of the control rod (34), and a second end (44b) hinged relative to the second end (42b) of the first connecting member (42).

4. Device (30) according to claim 2 or 3, wherein the drive mechanism (40) further comprises a guide casing (46) fastened to the body (32) of the ram and comprising at least one guide rail (47) cooperating with at least one guide pin (44c) carried by the second guide member (44).

5. Device (30) according to claim 4, wherein the guide rail (47) comprises a rectilinear main portion (47a), substantially parallel to the axis (X-X') of the turbomachine and a curve-shaped end portion (47b), said guide pin (44c) being located in a collection position inside said end portion (47b) in the safe position (PS) of the control rod (34).

6. Device (30) according to claim 4 or 5, wherein the guide casing (46) comprises two opposite guide rails (47, 48) each cooperating with a bearing (50) carried by the second connecting member (44).

7. Device (30) according to any one of claims 2 to 6, wherein the second end (34b) of the control rod (34) hinged relative to the first end (44a) of the second connecting member (44) is located upstream of the upstream end (33a) of the actuation rod (33) integral with the first connecting member (42).

8. Device (30) according to any one of claims 2 to 6, wherein the second upstream end (34b) of the control rod (34) hinged relative to the first end (44a) of the second connecting member (44) is located downstream of the upstream end (33a) of the actuation rod (33) integral with the first connecting member (42).

9. Device (30) according to any one of the preceding claims, wherein the actuation rod (33) is tubular and is axially crossed by the control rod (34), the latter being configured to be able to move inside the actuation rod (33).

10. Aircraft turbomachine (10) comprising, upstream to downstream in the flow direction of the air flow, an intake duct (11) receiving air, a centrifugal compressor (12), an annular combustion chamber (13), located downstream of the compressor (12), a high-pressure power turbine (14) intended to drive the compressor (12) in rotation, an output turbine (16) intended to drive an output shaft (17) in rotation, an air flow guide system (20) positioned upstream of the compressor (12) and a device (30) for controlling said air flow guide system (20) according to any one of the preceding claims.

11. Single-engine helicopter comprising a turbomachine (10) according to claim 10.

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