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A pressure-balancing device for balancing pressure in at least one bearing enclosure of a turbojet, the enclosure including a mechanism feeding the bearing with lubricating liquid, an air intake, at least one sealing system placed between the stator and the rotor in front of and/or behind the bearin

A pressure-balancing device for balancing pressure in at least one bearing enclosure of a turbojet, the enclosure including a mechanism feeding the bearing with lubricating liquid, an air intake, at least one sealing system placed between the stator and the rotor in front of and/or behind the bearing, a recovery mechanism recovering the lubricating liquid, and a removal mechanism removing the mixture of air and of traces of lubricating liquid towards a venting circuit. Downstream from the bearing enclosure and in the venting circuit, the balancing device includes a regulator system regulating the air removal flow rate, thereby enabling the flow rate to be variable as a function of the speed of the engine, to remain non-zero, and, at high speeds, to be lower than when the regulator system is not included.

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1. A pressure-balancing device for balancing pressure in at least one bearing enclosure of a turbojet, said enclosure being defined between a rotor mounted to rotate about an axis and a stator including a bearing support on which a bearing is mounted that bears against said rotor, said enclosure inc

1. A pressure-balancing device for balancing pressure in at least one bearing enclosure of a turbojet, said enclosure being defined between a rotor mounted to rotate about an axis and a stator including a bearing support on which a bearing is mounted that bears against said rotor, said enclosure including a device for feeding said bearing with lubricating liquid, an air intake bringing into the enclosure pressurized air coming from a pressurization circuit, at least one sealing system placed between the stator and the rotor in front of and/or behind said bearing, a recovery system for recovering the lubricating liquid and a removal system for removing the air towards a venting circuit, wherein downstream from the bearing enclosure and in a duct of the venting circuit, said device comprises: a regulator system for regulating the flow rate of air removal that, as a function of engine speed, changes the flow section of the duct between a non-zero minimum flow section and a maximum flow section thus enabling said flow rate to be variable as a function of engine speed, to remain non-zero, and, at high speeds, to be lower than when the regulator system is absent, andwherein said regulator system includes a shut-off member mounted to move between a closed position in which said shut-off member occupies a large fraction of the section of the duct that then has a minimum flow section and an open position in which said shut-off member occupies a small fraction of the section of the duct that then has a maximum flow section, it being possible for said shut-off member to take up any intermediate position between said closed position and said open position, andwherein the air removal flow rate is at a non-zero minimum value for low engine speed and is variable, increasing with increasing engine speed up to a maximum air removal flow rate. 2. A device according to claim 1, wherein the duct is stationary, and wherein said shut-off member is connected to a controller external to the duct and suitable for controlling the position of the shut-off member in the duct as a function of the engine speed. 3. A device according to claim 2, wherein the shut-off member is a plate mounted to pivot about an axis that is perpendicular to the main direction of the duct, the main plane of said plate being disposed transversely in the duct in the closed position in which there remains said minimum non-zero flow section between the plate and the wall of the duct for passing the minimum air flow rate, and the main plane of said plate being disposed parallel to the main direction of the duct in the open position. 4. A device according to claim 3, wherein the shut-off member is a circular plate provided with a through hole and having an outside diameter that is substantially equal to the inside diameter of the duct. 5. A turbojet comprising: at least a front enclosure and/or a rear enclosure, downstream from which, and downstream from a de-oiler, the venting circuit includes a duct mounted to rotate and a duct mounted to be stationary, wherein it includes a device according to claim 1, for which the regulator system is mounted downstream from the de-oiler. 6. A turbojet according to claim 5, wherein the de-oiler is mounted in an equipment support. 7. A pressure-balancing device for balancing pressure in at least one bearing enclosure of a turbojet, said enclosure being defined between a rotor mounted to rotate about an axis and a stator including a bearing support on which a bearing is mounted that bears against said rotor, said enclosure including a device for feeding said bearing with lubricating liquid, an air intake bringing into the enclosure pressurized air coming from a pressurization circuit, at least one sealing system placed between the stator and the rotor in front of and/or behind said bearing, a recovery system for recovering the lubricating liquid and a removal system for removing the air towards a venting circuit, wherein downstream from the bearing enclosure and in a duct of the venting circuit, said device comprises: a regulator system for regulating the flow rate of air removal that, as a function of engine speed, changes the flow section of the duct between a non-zero minimum flow section and a maximum flow section thus enabling said flow rate to be variable as a function of engine speed, to remain non-zero, and, at high speeds, to be lower than when the regulator system is absent, andwherein said regulator system includes a shut-off member mounted to move between a closed position in which said shut-off member occupies a large fraction of the section of the duct that then has a minimum flow section and an open position in which said shut-off member occupies a small fraction of the section of the duct that then has a maximum flow section, it being possible for said shut-off member to take up any intermediate position between said closed position and said open position, wherein the duct is mounted to rotate by the fact that it is fastened to the rotor and is thus driven in rotation by said rotor, and wherein said shut-off member is connected to a controller incorporated into the duct and changing the position of said shut-off member as a function of the speed of rotation of the rotor that varies with varying engine speed. 8. A device according to claim 7, wherein the shut-off member is a plate mounted to pivot about an axis that is perpendicular to the main direction of the duct, the main plane of said plate being disposed transversely in the duct in the closed position in which there remains said minimum non-zero flow section between the plate and the wall of the duct for passing the minimum air flow rate, and the main plane of said plate being disposed parallel to the main direction of the duct in the open position and wherein the control means comprise a control rod having one of its ends connected via a ball joint to said plate, a flyweight connected via a ball joint to the other of the ends of the control rod and provided with a through hole, and a drive rod fastened to said duct while being disposed in a direction that slants relative to a plane transverse to said duct, said flyweight being mounted to slide about said drive rod. 9. A device according to claim 7, wherein said shut-off member has two flaps mounted to pivot about a common shut-off member pin disposed perpendicularly to the main direction of the duct, and wherein, for each flap, the controller comprise a spring mounted between the flap and a support, so that the flaps open under the effect of the centrifugal force while the rotor is rotating, said springs urging the flaps back into the closed position. 10. A device according to claim 9, wherein it further includes a flyweight mounted on each flap or branch of the shut-off member. 11. A device according to claim 7, wherein said shut-off member has two branches mounted around a common shut-off member pin disposed perpendicularly to the main direction of the duct, said branches being made of an elastic material, so that the branches open under the effect of the centrifugal force while the rotor is rotating, and return to the closed position when the speed of rotation of the rotor decreases. 12. A turbojet comprising: at least a front enclosure and/or a rear enclosure including a venting circuit that, downstream from a de-oiler, includes a duct inside the low-pressure rotor, wherein it includes a pressure-balancing device for balancing pressure in at least one bearing enclosure of said turbojet, said enclosure being defined between a rotor mounted to rotate about an axis and a stator including a bearing support on which a bearing is mounted that bears against said rotor, said enclosure including a device for feeding said bearing with lubricating liquid, an air intake bringing into the enclosure pressurized air coming from a pressurization circuit, at least one sealing system placed between the stator and the rotor in front of and/or behind said bearing, a recovery system for recovering the lubricating liquid and a removal system for removing the air towards a venting circuit,wherein downstream from the bearing enclosure and in a duct of the venting circuit, said pressure-balancing device includes a regulator system for regulating the flow rate of air removal that, as a function of engine speed, changes the flow section of the duct between a non-zero minimum flow section and a maximum flow section thus enabling said flow rate to be variable as a function of engine speed, to remain non-zero, and, at high speeds, to be lower than when the regulator system is absent, andwherein said regulator system includes a shut-off member mounted to move between a closed position in which said shut-off member occupies a large fraction of the section of the duct that then has a minimum flow section and an open position in which said shut-off member occupies a small fraction of the section of the duct that then has a maximum flow section, it being possible for said shut-off member to take up any intermediate position between said closed position and said open position, wherein the duct is mounted to rotate by the fact that it is fastened to the rotor and is thus driven in rotation by said rotor, andwherein said shut-off member is connected to a controller incorporated into the duct and changing the position of said shut-off member as a function of the speed of rotation of the rotor that varies with varying engine speed, for which pressure-balancing device the regulator system is mounted in the low-pressure rotor. 13. A turbojet comprising: at least a front enclosure and/or a rear enclosure including a venting circuit that, downstream from the low-pressure rotor, includes a stationary duct, wherein it includes a pressure-balancing device for balancing pressure in at least one bearing enclosure of said turbojet, said enclosure being defined between a rotor mounted to rotate about an axis and a stator including a bearing support on which a bearing is mounted that bears against said rotor, said enclosure including a device for feeding said bearing with lubricating liquid, an air intake bringing into the enclosure pressurized air coming from a pressurization circuit, at least one sealing system placed between the stator and the rotor in front of and/or behind said bearing, a recovery system for recovering the lubricating liquid and a removal system for removing the air towards a venting circuit,wherein downstream from the bearing enclosure and in a duct of the venting circuit, said pressure-balancing device includes a regulator system for regulating the flow rate of air removal that, as a function of engine speed, changes the flow section of the duct between a non-zero minimum flow section and a maximum flow section thus enabling said flow rate to be variable as a function of engine speed, to remain non-zero, and, at high speeds, to be lower than when the regulator system is absent, andwherein said regulator system includes a shut-off member mounted to move between a closed position in which said shut-off member occupies a large fraction of the section of the duct that then has a minimum flow section and an open position in which said shut-off member occupies a small fraction of the section of the duct that then has a maximum flow section, it being possible for said shut-off member to take up any intermediate position between said closed position and said open position, for which pressure-balancing device the regulator system is mounted in said stationary duct, andwherein the air removal flow rate is at a non-zero minimum value for low engine speed and is available, increasing with increasing engine speed up to a maximum air removal flow rate. 14. A method of balancing pressure in at least one bearing enclosure of a turbojet, said enclosure being defined between a rotor mounted to rotate about an axis and a stator including a bearing support on which a bearing is mounted that bears against said rotor, said enclosure including a device for feeding said bearing with lubricating liquid, an air intake bringing into the enclosure pressurized air coming from a pressurization circuit, at least one sealing system placed between the stator and the rotor in front of and/or behind said bearing, a recovery system for recovering the lubricating liquid and a removal system for removing the air towards a venting circuit, the method comprising: regulating, as a function of engine speed, the air removal flow rate downstream from the bearing enclosure, in a duct of the venting circuit; andchanging as a function of engine speed, the flow section of the duct between a minimum flow section that is not zero and a maximum flow, by which said air flow rate is variable as a function of the speed of the engine, non-zero, and, at high speeds, lower than when the flow rate of air is not regulated, andwherein said flow rate is regulated by a shut-off member mounted to move between a closed position in which said shut-off member occupies a large fraction of the section of the duct that then has a minimum flow section and an open position in which said shut-off member occupies a small fraction of the section of the duct that then has a maximum flow section, it being possible for said shut-off member to take up any intermediate position between said closed position and said open position, and wherein the air removal flow rate is at a non-zero minimum value for low engine speed and is variable, increasing with increasing engine speed up to a maximum air removal flow rate. 15. A turbojet comprising: at least a front enclosure and/or a rear enclosure, downstream from which, and downstream from a de-oiler, the venting circuit includes a duct mounted to rotate and a duct mounted to be stationary, wherein it includes a device according to claim 7, for which the regulator system is mounted downstream from the de-oiler.