RTX Corporation
Roller bearings for high ratio geared turbofan engine

Abstract:

A gear system for a geared turbofan engine is disclosed. The gear system includes a sun gear driven by a low spool shaft. The sun gear defines a sun gear diameter. A rotating carrier drives a fan. The carrier defines an outer carrier diameter and an inner carrier diameter. A non-rotating ring gear is also included. The ring gear defines a ring gear diameter and the ring gear diameter is smaller than the outer carrier diameter. A set of planet gears are mounted on corresponding rolling element bearing assemblies. Each roller element bearing assembly is supported within the carrier within a space defined between the carrier outer diameter and the carrier inner diameter. Each of the sun gear, ring gear and planet gears are substantially centered along a gearbox centerline transverse to an engine longitudinal axis and the gear system provides a speed reduction ratio between an input to the sun gear and an output from the carrier between 3:1 and 5:1. A method of creating a gear system for a geared turbofan engine and a geared turbofan system are also disclosed.