CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. § 371 filing of International Application No. PCT/FR2018/050897 filed Apr. 10, 2018, which claims the benefit of priority to French Patent Application No. 1753296 filed Apr. 14, 2017, each of which is incorporated herein by reference in its entirety.

The field of the present invention is that of turbomachinery and more particularly epicycloidal gear trains and among epicycloidal gear trains more specifically epicycloidal reducers and differential transmissions.

Typically, an epicycloidal gear train consists of a planetary or central pinion, a planetary or outer crown and satellite pinions that are in engagement with the planetary pinion and the crown, the support of one of these three components being locked in rotation for the operation of the gear train. When the satellite carrier is fixed in rotation, the central pinion and crown are driving and driven, respectively, or vice versa. The lubrication and cooling of the gears and axes of the satellite pinions is then not a problem and is ensured by nozzles that are fixed in rotation and can project oil permanently on the meshing areas of the satellite pinions with the central pinion and with the crown and on the satellite pinion axes.

However, in the most frequent case, the outer crown is fixed in rotation and the central pinion and the satellite carrier are driving and driven, respectively. This type of arrangement is preferred in cases where a reduction ratio of more than three is desired since it is less cumbersome. Lubrication of the meshing zones and satellite pinion shafts is then a problem that is solved in current technology by complex networks of pressurized oil routing pipes, using dynamic seals or rotating joints that are subject to wear and which must be checked and replaced regularly.

Thus, the applicant proposed in her application WOA12010092263 a lubrication device in which a fixed injector sprays oil into an annular cup fixed to a satellite carrier, the oil being recovered by centrifugation and then directed to means for lubricating the pinions. This device avoids the use of dynamic or rotating seals, which improves the reliability of the reducer lubrication system and its maintenance.

In a second known configuration, the nozzle can be carried by the shaft carrying the central pinion so that its oil jet is directed towards the cup.

However, in either of the two above-mentioned configurations, at low rotation speed, the oil flow from the nozzles may be too high in relation to the rotation speed of the satellite carrier so that oil accumulates in the annular cup, leading to parasitic oil spills. In addition, excess oil can circulate inside the satellite pinion axes, leading to excessive heating of the oil, which should be cooled later.

The purpose of the invention is in particular to provide a simple, effective and economical solution to the problems of the prior art described above.

To this end, the present invention offers an epicycloidal gear train comprising a central pinion, an outer crown and satellite pinions in engagement with the central pinion and the outer crown and each mounted freely rotatable on a satellite carrier, the gear train comprising a first lubrication oil circuit for the contact areas of the satellite pinion teeth with the central pinion and a second lubrication oil circuit for the satellite pinion axes, an annular cup being integral with the satellite carrier and open radially inward, characterized in that the cup is divided into a circumferential succession of first basins of the first oil circuit and second basins of the second oil circuit, the first basins being fluidly separated from the second basins and in that the cup comprises two axially opposite annular walls whose annular wall furthest from a median transverse plane of the gear train comprises openings leading to the second basins.

According to the invention, the openings made in the portions of the wall delimiting the second basins laterally allow the excess oil to escape through the openings.

Preferably, openings are only made in the portions of the wall delimiting the second basins, while the first basins that provide an oil supply to the contact areas of the satellite pinion teeth with the central pinion do not include an opening to avoid reducing the pressure in the first circuit.

According to the invention, the openings are formed circumferentially in the annular wall furthest from the transverse plane, at the level of the parts delimiting the second basins.

According to another characteristic of the invention, the openings include notches delimiting a part of the radially inner annular edge of said annular wall so that said annular edge is notched. The notches can have a depth, in radial direction, of about 20 to 50% of the depth of the first basins.

In a particular embodiment of the invention, the notches extend over the entire angular distance of a second basin.

The invention is particularly interesting when the first basins are connected to first oil supply lines in the contact area between the gear teeth of the satellite pinions and the central pinion teeth, and the second basins are connected to second oil supply lines of the satellite pinion axes.

The invention also concerns a turbomachine comprising a gear train as described above, the central pinion of which surrounds and is rotationally fixed to a shaft of the turbomachine, and oil spraying means arranged radially outside the shaft and having at least one oil nozzle spraying oil towards the annular cup.

Said nozzle can be carried by the outer surface of the shaft and positioned so that its oil jet is directed towards the cup.

The gear train is, advantageously, a reducer and is mounted in an annular chamber formed radially inside a low-pressure compressor, the satellite carrier being connected to an upstream fan wheel and the shaft being a shaft of the low-pressure compressor.

In a particular assembly configuration, the gear unit is axially interposed between an upstream and a downstream bearing supported by a stator structure of the low-pressure compressor, the upstream bearing guiding in rotation a connecting shaft from the fan wheel to the satellite carrier and the downstream bearing guiding in rotation the shaft of the low-pressure compressor.

Also, the first fixed oil spraying means can be integrated into an oil circuit further comprising second oil spraying means on the upstream and downstream bearings and a pump for simultaneous feeding the first and second oil spraying means. This makes it possible to simplify the design of the oil supply to the turbomachine.

The invention is, for example, applicable to a gear train, such as a gear train in which the outer crown is fixed. In this case, the gear train can be called a reducer since the output speed, i. e. that of the satellite carrier, is lower than the input speed, i. e. that of the rotating drive shaft of the central pinion. The invention also relates to a differential transmission gear train, in which the satellite carrier and the outer crown are movable in rotation in opposite directions, the satellite carrier preferably driving a first upstream fan wheel and the outer crown preferably driving a second downstream fan wheel. With such an arrangement, a double counter rotating fan wheel assembly is obtained.

