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CN-121986225-A - Mechanical reduction gear for an aircraft turbine engine

CN121986225ACN 121986225 ACN121986225 ACN 121986225ACN-121986225-A

Abstract

A mechanical reduction gear (60 ') for a turbine engine (1), in particular for an aircraft, comprising-a sun gear (70), -a ring gear (90), -planet gears (80) carried by a planet carrier (100) and meshing with the sun gear (70) and the ring gear (90), -fluid-dynamic guide bearings (81') for guiding rotation of the planet gears (80), each of the planet gears (80) being guided by two fluid-dynamic bearings (81 '), the two fluid-dynamic bearings being independent of each other and one being located on one side of a plane (H), the two fluid-dynamic guide bearings (81') of each of the planet gears (80) being positioned around a barrel (86) of the planet gears (80) and one being located on one side of a web (88) of the planet gears (80).

Inventors

  • Balint Papp
  • Dave Giribi
  • Guillaume Pierre Morley

Assignees

  • 赛峰传动系统公司

Dates

Publication Date
20260505
Application Date
20241002
Priority Date
20231010

Claims (15)

  1. 1. A mechanical reduction gear (60') for a turbine engine (1), in particular for an aircraft, comprising: a sun gear (70) having an axis of rotation (X), A ring gear (90) extending around the sun gear (70), -Planetary gears (80) carried by a planet carrier (100) and meshing with the sun gear (70) and the ring gear (90), each planetary gear (80) comprising a first tooth (82) for meshing with the sun gear (70) and a second tooth (84) for meshing with the ring gear (90), the first tooth having a first average diameter, the second tooth having a second average diameter different from the first average diameter, the first and second teeth (82, 84) of each planetary gear (80) being symmetrical with respect to a plane (H) perpendicular to the axis (X) and passing substantially through the middle of the planetary gears (80), the first tooth (82) being divided into two by the plane (H) or comprising two series of teeth (82 d1,82d 2) axially arranged on either side of the plane (H), and the second tooth (84) comprising a cylindrical portion (84) extending from the middle of the first tooth (82) and the second tooth (84) of the series (84) to the cylindrical portion (84) of the cylindrical portion (86), and the first tooth (82) or the tooth portion (82 d1,82d 2) of the first tooth (82) is located at the outer periphery of the web (88), Hydrodynamic bearings (81 ') for guiding the rotation of the planetary gears (80), these hydrodynamic bearings (81 ') being configured to be supplied with oil and to form an oil film for guiding the planetary gears (80), each of the planetary gears (80) being guided by two hydrodynamic bearings (81 ') which are independent of each other and are arranged axially on both sides of the plane (H), Characterized in that two hydrodynamic bearings (81') for guiding each of the planetary gears (80) are positioned around a cylindrical portion (86) of the planetary gear (80) and axially on both sides of a web (88) of the planetary gear (80).
  2. 2. The mechanical reduction gear (60 ') according to claim 1, wherein the two hydrodynamic bearings (81') for guiding each of the planetary gears (80) are positioned in radial alignment with the first tooth (82) or the series of teeth (82 d1,82d 2) of the first tooth (82), respectively.
  3. 3. The mechanical reduction gear (60 ') according to claim 1 or 2, wherein each of the two hydrodynamic bearings (81') for guiding each of the planetary gears (80) is axially located between the first tooth (82) or a series of teeth (82 d1,82d 2) of the first tooth (82) and a series of teeth (84 d1,84d 2) of the series of teeth of the second tooth (84).
  4. 4. The mechanical reduction gear (60 ') according to any of the preceding claims, wherein each of the hydrodynamic bearings (81') for guiding each of the planetary gears (80) cooperates with an inner cylindrical surface (92) of a web (88) of the planetary gear (80) and/or an outer cylindrical surface (94) of a cylindrical portion (86) of the planetary gear (80).
  5. 5. The mechanical reduction gear (60') according to claim 4, wherein the inner cylindrical surface (92) and/or the outer cylindrical surface (94) are adapted to form an oil film.
  6. 6. The mechanical reduction gear (60') according to claim 4 or 5, wherein the inner cylindrical surface (92) and the outer cylindrical surface (94) are arranged in radial alignment with each other.
  7. 7. The mechanical reduction gear (60') according to any one of claims 4 to 6, wherein the diameter (D3) of the inner cylindrical surface (92) is greater than the maximum diameter (D4) of the barrel (86).
  8. 8. The mechanical reduction gear (60') according to any one of claims 4 to 7, wherein the inner cylindrical surface (92) extends radially below a series of teeth (82 d1,82d 2) of the series of teeth (82 d1,82d 2) along an axial extent (L3) comprised between 30% and 70% of the axial extent (L1) of the series of teeth (82 d1,82d 2).
  9. 9. The mechanical reduction gear (60') according to any one of claims 4 to 8, wherein the outer cylindrical surface (94) of the barrel (86) is located at a maximum diameter (D4) of the barrel (88).
  10. 10. The mechanical reduction gear (60') according to any one of claims 4 to 9, wherein the outer cylindrical surface (94) of the barrel (86) extends according to an axial extent (L4) radially below one of the series of teeth (82 d1,82d 2) of the first tooth (82) and which is comprised between 100% and 200% of the axial extent (L1) of that series of teeth (82 d1,82d 2).
  11. 11. Mechanical reduction gear (60 ') according to any one of claims 4 to 10, wherein the inner cylindrical surface (92) and/or the outer cylindrical surface (94) is supplied with oil through a lubrication channel (96) formed in the planet carrier (100), preferably through a lubrication channel (96) passing through the two hydrodynamic bearings (81').
  12. 12. The mechanical reduction gear (60 ') according to any one of claims 1 to 11, wherein the two hydrodynamic bearings (81') for guiding each of the planetary gears (80) are integral with the planet carrier (100).
  13. 13. The mechanical reduction gear (60 ') according to any one of claims 1 to 11, wherein the two hydrodynamic bearings (81 ') for guiding each of the planetary gears (80) respectively comprise two cylindrical bodies (81 a ') surrounding a cylindrical portion (86) of the planetary gear (80), axially arranged on both sides of a web (88) of the planetary gear (80), and carried by the planet carrier (100).
  14. 14. Mechanical reduction gear (60') according to any one of the preceding claims, wherein the outer periphery of the web (88) comprises through openings (98) for discharging oil, which are axially located on both sides of the plane (H) and preferably axially between the series of teeth (82 d1,82d 2) of the first tooth (82).
  15. 15. Turbine engine (1), in particular for an aircraft, comprising a mechanical reduction gear (60') according to any one of the preceding claims.

Description

Mechanical reduction gear for an aircraft turbine engine Technical Field The present invention relates to the field of mechanical reduction gears for turbine engines, in particular for aircraft. Background The prior art includes, inter alia, literature WO-A1-2010/092263、FR-A1-2 987 416、FR-A1-3 008 462、FR-A1-3 008 463、FR-A1-3 041 054、FR-A1-3 095 251、FR-A1-3 116 096、EP-A1-4 001 619 and EP-A1-3 726 031. The function of the mechanical reduction gear is to change the speed and torque ratio between the input and output shafts of the mechanical system. New generation dual flow turbine engines (particularly those with high bypass ratios) include mechanical reduction gears to drive the shaft of the fan. The general purpose of a reduction gear is to convert the rotational speed of the shaft of the power turbine (referred to as high speed) into a slower rotational speed of the shaft for driving the fan. Such reduction gears include a sun pinion, known as a sun gear, a ring gear, and pinions, known as planet gears, meshed between the sun gear and the ring gear. The planet gears are held by a frame called a planet carrier. The sun gear, ring gear and planet carrier are planetary gears in that their axes of rotation coincide with the longitudinal axis X of the turbine engine. The planet gears each have a different axis of rotation, the planet gears each being equally distributed about the axis of the planetary gear over the same operating diameter. These axes are parallel to the longitudinal axis X. There are a variety of reduction gear architectures. In the prior art of dual flow turbine engines, the reduction gear is of the planetary or planetary type. In other similar applications, there are architectures known as differential or "compound". In a planetary reduction gear, the planet carrier is fixed and the ring gear is the output shaft of the device, which rotates in the opposite direction to the sun gear. In the planetary reduction gear, the ring gear is fixed and the planet carrier is the output shaft of the device, which rotates in the same direction as the sun gear. On the differential reduction gear no element is attached to rotate. The ring gear rotates in a direction opposite the sun gear and the carrier. The reduction gear may be comprised of one or more meshing stages. The engagement is ensured in different ways, for example by contact, friction or a magnetic field. In the present application, "stage" or "tooth" refers to a series of meshing teeth having a series of complementary teeth. The teeth may be internal or external. The planetary gears may include one or two meshing stages. The single stage planetary gear includes teeth, which may be straight, helical or herringbone, and the teeth are located on the same diameter. The teeth cooperate with the sun gear and the ring gear. The two-stage planetary gear includes two teeth or two series of teeth on different diameters. The first teeth cooperate with the sun gear and the second teeth cooperate with the ring gear. Furthermore, each planetary gear is centered on and guided for rotation about an axis by a bearing carried by the planet carrier. There are a variety of bearing technologies that can be used with the present application, and the present application relates specifically to the use of hydrodynamic bearings in a mechanical reduction gear for guiding a planetary gear. In the present application, "hydrodynamic bearing" refers to a bearing comprising a body that is engaged in a planetary gear and around which an oil film is arranged under pressure. In the prior art, the hydrodynamic bearing of the planetary gear comprises a cylindrical body comprising an outer cylindrical surface which extends into the inner cylindrical surface of the planetary gear. The pressurized oil film is interposed between these surfaces and leaves no contact between these surfaces. One of the drawbacks of this type of reduction gear is the relatively large axial dimension of the planetary gear, which is subjected to large loads due to the transmission of torque at the mesh and, in the case of the planetary reduction gear, the centrifugal effect applied to the planetary gear. Therefore, the bearing that supports the pinion and guides the rotation of the pinion is loaded, and there is little room for integrating the bearing without significantly increasing the overall size of the reduction gear. Rolling bearings with rolling elements can be used as bearings. However, the load capacity of the rolling elements does not allow the rolling elements to be arranged below the teeth of the planetary gears, and therefore the rolling elements must be arranged outside the planetary gears to give the rolling elements a sufficient diameter, which increases the overall size of the reduction gear considerably. Therefore, from the standpoint of overall size, it is preferable to use a sliding bearing or a hydrodynamic bearing having a high load capacity. This enables the bearing to be arranged belo