SEALING DEVICE FOR AN OUTLET VALVE OF A TURBOMACH

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The field of the invention is that of turbomachine casing relief valves, and in particular turbomachine intermediate casings.

[0002] The present invention relates more particularly to a sealing device for a turbomachine discharge valve, and to a turbomachine valve comprising such a sealing device. TECHNICAL BACKGROUND

[0003] The technical background includes in particular documents EP 0 374 004 A1, FR 3 096 083 A1 and FR 3 089 270 A1.

[0004] In a turbomachine, wastegates, also known by their acronym VDV for Variable Bleed Valve (or VBV for Variable Bleed Valve in English), are generally mounted on the hub of an intermediate casing of a turbomachine with a double-flow, positioned between the low-pressure compressor and the high-pressure compressor. The wastegates are positioned in an annular inter-vein space of the hub of the intermediate casing extending between a main flow vein (primary vein) in which a primary air flow circulates and a secondary flow vein (secondary vein) in which a secondary air flow circulates.

[0005] Their opening and closing then serve to adjust an air leakage flow rate according to the operating conditions of the turbomachine, for example to avoid surge. These discharge valves are regularly distributed on the hub of the intermediate casing around the longitudinal axis of the turbomachine and each comprise a door pivotally mounted around an axis, so as to be angularly movable relative to the intermediate casing, between a closing position in which the door closes an air passage orifice provided in the hub of the intermediate casing and a position in which this orifice is open.

[0006] A control ring is positioned outside the duct between the compressor casing and an external cover of the turbomachine and is used to control the opening and closing of the discharge doors. Rotation of the ring activates lever-operated devices that drive the discharge doors.

[0007] The wastegates ensure the seal between the primary stream and the secondary stream in their closed position and allow the evacuation of a portion of the primary air flow from the primary stream under certain operating conditions in their open position. The portion of the primary air flow taken is either reinjected into the secondary air flow, or used to supply cooling systems or to ventilate components of the turbomachine. To ensure the seal between the primary stream and the secondary stream in the closed position of the wastegates, the wall of the intermediate casing bordering the air passage orifice has a seal, for example made of elastomer, extending around the periphery of the wall bordering the orifice. The seal is intended to bear, in the closed position of the wastegate, against peripheral edges of each door.

[0008] However, in the open position of the discharge door, the seal is no longer in compression against the discharge door. As a result, it extends into the airflow, which can cause a reduction in the passage section of the aerodynamic flow of scooped air.

[0009] One solution to this problem would be to increase the opening of the discharge valve door. However, the opening angle of the door is very limited and does not compensate for this loss in scooped airflow.

[0010] In this context, the invention aims to propose a solution to resolve these drawbacks. SUMMARY OF THE INVENTION

[0011] To this end, the invention relates to a discharge valve for an aircraft turbomachine, comprising a discharge door intended to be pivotally mounted around an axis between a position for closing an air passage orifice and an open position of said orifice, the orifice being arranged in an intermediate casing of the turbomachine, the discharge valve comprising a sealing device comprising: a seal configured to be movably mounted on the intermediate casing, and a movement system configured to move the seal between a first position in which the seal is intended to bear against the discharge door when the door is in the closed position and a second position in which the seal is retracted relative to the air passage orifice when the door is in the open position.

[0012] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, the invention makes it possible to ensure sealing between the intermediate casing and the door of a discharge valve in the closed position while avoiding obstruction of the aerodynamic air flow when the door is in the open position.

[0013] Indeed, thanks to the invention, the seal is thus advantageously retracted or retracted when the discharge door is in the open position, thus avoiding extending into the air flow when the seal is no longer compressed against the door. Thus, the entire passage section of the aerodynamic air flow between the discharge door and the intermediate casing is preserved without being penalized by the volume occupied by the seal.

[0014] The discharge valve according to the invention may also have one or more of the following characteristics, considered individually or in all technically possible combinations: the movement system is controlled, preferably mechanically, by the opening or closing of the discharge door; the movement system comprises a seal support configured to be slidably mounted in a cavity provided in the intermediate casing opening into the air passage orifice and an actuator configured to move the seal from the first position to the second position when it is actuated by the opening of the discharge door and from the second position to the first position when it is actuated by the closing of the discharge door, the seal being housed in the cavity of the intermediate casing in the second position;the movement system comprises a connecting rod configured to be pivotally mounted about an axis in the cavity of the intermediate casing, the connecting rod being articulated at one end on an axis secured to the support of the seal and controlled at the other end by the action of a spring forming an actuator, the spring being configured to return the connecting rod to a position in which the seal is held in the second position when the discharge door is in the open position and to be compressed by the discharge door when it is in the closed position so as to pivot the connecting rod into a position in which the seal is held in the first position; ; the sealing device comprises a stop configured to be fixed to the discharge door so as to compress the spring when the door is in the closed position; the discharge door is configured to project radially towards the inside of the intermediate casing in the open position defining a scooping volume and the stop is intended to be fixed to the discharge door outside said scooping volume.

[0015] Another subject of the invention relates to an intermediate turbomachine casing comprising a plurality of discharge valves according to the invention ensuring sealing at a plurality of air passage orifices.

[0016] The invention further relates to a turbomachine comprising a low-pressure compressor, a high-pressure compressor and an intermediate casing as described previously and positioned longitudinally between the low-pressure compressor and the high-pressure compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description of a non-limiting example which follows, with reference to the appended drawings in which: there figure 1 schematically illustrates, in axial section, a double-flow turbomachine to which the invention applies; the figure 2 is a simplified sectional view of an intermediate casing of the turbomachine of the figure 1 ; there figure 3 is a simplified sectional view of a portion of a turbomachine discharge valve illustrating the behavior of the seal according to the invention in the closed position of the discharge door; and the figure 4 schematically represents in section the portion of the turbomachine discharge valve of the figure 3 illustrating the behavior of the seal according to the invention in the open position of the discharge door.

[0018] In the various figures, similar elements are designated by identical references. Furthermore, the various elements are not necessarily shown to scale in order to present a view that facilitates understanding of the invention. DESCRIPTION OF EMBODIMENTS

[0019] A sealing device to which the invention relates is, for example, installed in an aircraft turbomachine, in particular a dual-flow one, comprising a low-pressure compressor.

[0020] In the present invention, and in general, the terms "upstream", "downstream", "axial" and "axially" are defined in relation to the circulation of gases in the turbomachine and here along the longitudinal axis X (and even from left to right on the figure 1 ). Similarly, the terms "radial", "internal" and "external" are defined with respect to a radial axis Y perpendicular to the longitudinal axis X and with respect to the distance from the longitudinal axis X.

[0021] As illustrated by the figure 1 which is a schematic axial sectional view of a dual-flow or double-spool turbomachine 10, such a turbomachine generally comprises, from upstream to downstream in the direction of gas flow, a low-pressure compressor 12, a high-pressure compressor 14, a combustion chamber 16, a high-pressure turbine 18 and a low-pressure turbine 20, which define a flow path for a primary gas flow F1.

[0022] The high pressure turbine 18 is integral with the high pressure compressor 14 so as to form a high pressure body, while the low pressure turbine 20 is integral with the low pressure compressor 12 so as to form a low pressure body, so that each turbine drives the associated compressor in rotation around the longitudinal axis 24 of the turbomachine under the effect of the thrust of the gases coming from the combustion chamber 16.

[0023] In such a turbomachine 10, an intermediate casing 26 is usually interposed between the low pressure compressor 12, located upstream, and the high pressure compressor 14, located downstream. The intermediate casing 26 has a generally cylindrical or truncated cone shape.

[0024] In the case of dual-flow turbomachines, which comprise a fan 28 shrouded by a nacelle 30 to generate a secondary flow F2, the intermediate casing 26 generally comprises arms 34 crossing the flow path of this secondary flow 32.

[0025] There figure 2 illustrates a simplified view of an intermediate casing 26 on which discharge valves 48 are mounted at the hub 36 of the intermediate casing 26. This hub 36 comprises two coaxial annular shells, respectively internal 38 and external 44, and two radial walls or flanges, respectively upstream 40 and downstream 42, connecting the internal 38 and external 44 shells. The internal shell 38 delimits the external part relative to the axis 24 of the primary flow space, or primary vein, of the primary flow F1 of the turbomachine.

[0026] Furthermore, this hub 36 is equipped with an annular row of discharge valves 48, one of which is visible in section on the figure 2 . This figure shows more specifically the door 50 of the valve 48, which is pivotally mounted around an axis 51, so as to be movable between an open position and a closed position of a corresponding orifice formed in the internal ferrule 38 of the hub 36.

[0027] Each of the discharge air inlet orifices 60, of substantially parallelepiped shape, is associated with a discharge valve 48 intended for regulating the flow rate of the high pressure compressor 14.

[0028] A control device for opening and closing the discharge doors is more visible on the figure 3 and comprises a single-piece circular ring 62 for controlling the opening or closing of the discharge doors depending on the operating conditions of the turbomachine. This ring 62 is centered on the longitudinal axis 24 of the turbomachine and placed in the space surrounding the casing 26. The rotation of the control ring 62 is carried out by actuators which are also located outside the casing 26. The rotation of the control ring 62 actuates lever actuation devices driving the discharge doors 50. Thus, for each discharge door 50, a lever actuation device 64 is fixed by a fastener 66 to the control ring, so as to transform the rotational movement of the ring 62 around the axis 24 of the casing into an opening or closing movement of the door 50. The fastener 66 is arranged to form a suitable connection between the control ring 62 and the elements of the lever device 64.Here, it is a pivot connection around a substantially radial axis between the control ring 62 and a bell crank of the lever device 64. The opening of each valve 48 causes the discharge of an air flow (arrow 52 in dotted lines) into the annular space delimited by the ferrules 38, 44 and the radial walls 40, 42.

[0029] The downstream radial wall 42 delimits, for its part, the internal part with respect to the axis X of the secondary flow space, secondary vein, of the secondary flow F2. It comprises an annular row of orifices 54 for the passage of the discharge air flows 52, towards the downstream. As can be seen in figure 2 , discharge ducts 56 are mounted downstream of the intermediate casing 26 and are each intended to guide an air flow 52 caused by the opening of a discharge valve 48, the air flow being guided from the outlet of the orifices 54 to the flow vein of the secondary flow F2.

[0030] There figure 3 represents more precisely a portion of a discharge valve 48 of an intermediate casing 26 of a turbomachine 10 according to the invention.

[0031] Each discharge door 50 has a substantially parallelepiped shape complementary to that of the corresponding discharge air inlet orifice 60. The function of the door 50 is to ensure a seal between the primary flow F1 and the secondary flow F2 and to authorize a discharge flow rate between the primary flow F1 and the secondary flow F2 according to a control program of the discharge valve 48.

[0032] The discharge door 50 is configured to pivot about a transverse axis 51 which is substantially tangent to the intermediate casing 26 and which extends substantially along the downstream peripheral edge of the door 50 in the examples illustrated in the figures.

[0033] The door 50 is therefore angularly movable by pivoting around the transverse axis 51 between a closed or obturation position and an open position of this orifice 60.

[0034] In the closed position, the inner surface 68 of the door 50 is aligned with the surface of the inner annular ferrule 38 of the intermediate casing 26.

[0035] In the open position, the door 50 is inclined at an angle of approximately 60° towards the inside of the intermediate casing 12 relative to its closed position, as is more clearly visible in the figure 4 . Thus, the discharge door 50 is configured to protrude radially towards the inside of the intermediate casing 26 in the open position defining a scooping volume.

[0036] In order to ensure the sealing of the primary vein in the closed position of the discharge door 50, the latter comprises a sealing device 70 equipped with a seal 72 configured to be mounted movably on the intermediate casing 26 and a movement system 74 configured to move the seal 72 relative to the intermediate casing 26. In particular, the movement system 74 is configured to move the seal 72 between a first position, called extended, in which the seal 72 is in abutment against the discharge door 50 when the door is in the closed position and a second position, called retracted, in which the seal 72 is retracted relative to the air passage orifice 60 when the door 50 is in the open position.

[0037] The seal 72 extends longitudinally in a transverse direction which is substantially tangent to the intermediate casing 26 and which extends substantially along the upstream peripheral edge of the discharge door 50 so as to come to bear against it, in the closed position of the discharge door illustrated in the figure 3 . It has over its entire length a bead or curved part 76 directed towards the inside of the intermediate casing 26 and intended to be compressed by the discharge door 50 when the latter is in the closed position in order to guarantee the sealing of the discharge valve 48.

[0038] The movement system 74 is controlled, preferably mechanically, by the opening or closing of the discharge door 50.

[0039] For this purpose, the displacement system 74 comprises a seal support 78 of a shape adapted to that of the seal 74 in order to support the entire seal. A flat face of the sealing seal opposite the domed portion 76 is held to the support 78 by gluing.

[0040] The support 78 is slidably mounted in a cavity 80 provided in the intermediate casing 26.

[0041] The cavity 80 extends longitudinally in a transverse direction which is substantially tangent to the intermediate casing 26 and extends substantially along the upstream peripheral edge of the air passage orifice 60 and further has a depth in a radial direction. The cavity 80 is thus shaped to house the seal 72 in the second position, i.e. when the door is open. In addition, the cavity 80 is open at one end and opens into the air passage orifice 60 in order to allow the seal 72 to project radially into the passage orifice 60 to bear against an external surface 82 of the door 50 when the latter is in the closed position.

[0042] The movement system 74 comprises a connecting rod 84 configured to be pivotally mounted around a transverse axis 86 substantially tangent to the intermediate casing 26 in the cavity 80. The connecting rod 84 is furthermore articulated at one end on an axis 87 secured to the support 78 of the sealing joint and controlled at the other end by an actuator.

[0043] The actuator is configured to move the seal 72 from the first extended position to the second retracted position when actuated by opening the discharge door 50 and from the second retracted position to the first extended position when actuated by closing the discharge door 50.

[0044] Preferably, the actuator is a spring 89 configured to return the link 84 to a position in which the seal 72 is held in the retracted position. The link 84 is thus articulated at the other end on an axis 88 secured to one end of the spring 89.

[0045] The spring 89 is further configured to be compressed by the discharge door 50 when it is in the closed position so that the link is pivoted into a position in which the seal 72 is held in the first extended position.

[0046] The sealing device 70 advantageously comprises a stop 90 fixed to the discharge door 50 and which extends longitudinally in a radial direction so as to compress the spring 89 when the door is in the closed position. Thus, it is directly the door 50 itself which sets in motion the kinematics of the retractable seal 72. Preferably, the stop 90 is fixed to the discharge door 72 outside the scooping volume in order to maximize the flow of air scooped by the discharge door.

[0047] In operation, when the discharge valve gate 50 is closed, as shown in the figure 3 , the spring 89 is compressed by the discharge door 50, preferably via the stop 90. Thus, the connecting rod 84 is kept pivoted by the spring in a position such that the seal 72 is kept in the first extended position, that is to say projecting radially into the passage orifice 60 and bearing against the external surface 82 of the door 50, its domed part 76 being compressed.

[0048] When the discharge valve gate 50 opens (see figure 4 ), it no longer compresses the spring 89 which relaxes and thus pivots the connecting rod 84 around the transverse axis 86 so as to slide the seal support 78 and thus retract the sealing gasket 72 into the cavity 80 outside the air passage orifice 60.

[0049] Thus, the seal no longer extends into the passage section of the aerodynamic air flow, thus maximizing the air flow scooped by the door.

[0050] The invention as described above provides a compact solution ensuring sealing between the intermediate casing and the door of a discharge valve in the closed position while avoiding obstruction of the aerodynamic air flow when the door is in the open position.

Claims

1. A discharge valve (48) for an aircraft turbomachine (10), comprising a discharge gate (50) intended to be mounted to pivot about an axis (51) between a position for closing an air passage orifice (60) and an open position of said orifice, the orifice being provided in an intermediate casing (26) of the turbomachine, the discharge valve comprising a sealing device (70), the discharge valve being characterized in that the sealing device (70) comprises: - a seal (72) configured to be movably mounted on the intermediate casing (26), and - a movement system (74) configured to move the seal (72) between a first position in which the seal (72) is intended to bear against the discharge gate (50) when the gate is in the closing position and a second position in which the seal (72) is retracted with respect to the air passage orifice (60) when the discharge gate (50) is in the open position.

2. The discharge valve according to claim 1, in which the movement system (74) is controlled by the opening or closing of the discharge gate (50).

3. The discharge valve according to claim 2, wherein the movement system (74) comprises a seal support (78) configured to be slidably mounted in a cavity (80) provided in the intermediate casing (26) opening into the air passage orifice (60) and an actuator configured to move the seal (72) from the first position to the second position when actuated by the opening of the discharge gate (50) and from the second position to the first position when actuated by the closing of the discharge gate, the seal (72) being housed in the cavity (80) of the intermediate casing (26) in the second position.

4. The discharge valve according to claim 3, wherein the movement system (74) comprises a connecting rod (84) configured to be mounted so as to pivot about an axis (86) in the cavity (80) of the intermediate casing (26), the connecting rod (84) being articulated at one end on an axis (87) secured to the support (78) of the seal (72) and controlled at the other end by the action of a spring (89) forming an actuator, the spring (89) being configured to return the connecting rod (84) to a position in which the seal (72) is held in the second position when the discharge gate (50) is in the open position and to be compressed by the discharge gate (50) when it is in the closing position so as to pivot the connecting rod (84) into a position in which the seal (72) is held in the first position.

5. The discharge valve according to claim 4, comprising a stop (90) configured to be fixed to the discharge gate (50) so as to compress the spring (89) when the discharge gate (50) is in the closing position.

6. The discharge valve according to claim 5, wherein the discharge gate (50) is configured to project radially towards the inside of the intermediate casing (26) in the open position defining a scooping volume and the stop (90) is intended to be fixed to the discharge gate outside said scooping volume.

7. A turbomachine intermediate casing (26) comprising a plurality of discharge valves (48) according to any one of the preceding claims ensuring sealing at the level of a plurality of air passage orifices (60).

8. The turbomachine (10) comprising a low-pressure compressor (12), a highpressure compressor (14) and an intermediate casing (26) according to the preceding claim positioned longitudinally between the low-pressure compressor and the highpressure compressor.