Gearboxes for aircraft gas turbine engines
AssigneeROLLS-ROYCE plc
InventorMark Spruce
Life of this patent
Estimating the term…
Abstract
Gearboxes for aircraft gas turbine engines, in particular arrangements for journal bearings such gearboxes, and related methods of operating such gearboxes and gas turbine engines. A gearbox for an aircraft gas turbine engine includes: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin.
Claims20
A gas turbine engine for an aircraft, comprising:
- an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor;
- a fan located upstream of the engine core, the fan comprising a plurality of fan blades;
- and
- a gearbox configured to receive an input from the core shaft and provide an output drive to the fan so as to drive the fan at a lower rotational speed than the core shaft, the gearbox comprising:
- a sun gear;
- a plurality of planet gears surrounding and engaged with the sun gear;
- and
- a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin, wherein:
- the gearbox has a gear ratio in the range 3.2 to 4.5;
- wherein the gas turbine engine is configured such that during operation a maximum specific load of each journal bearing is in the range of 5 MPa to 25 MPa.
A gas turbine engine for an aircraft, comprising:
- an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor;
- a fan located upstream of the engine core, the fan comprising a plurality of fan blades;
- and
- a gearbox configured to receive an input from the core shaft and provide an output drive to the fan so as to drive the fan at a lower rotational speed than the core shaft, the gearbox comprising:
- a sun gear;
- a plurality of planet gears surrounding and engaged with the sun gear;
- and
- a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin, wherein:
- an inefficiency of each journal bearing, defined as a percentage power loss with the aircraft gas turbine engine operating at maximum take-off conditions is less than 0.225%;
- and
- the gas turbine engine is configured such that during operation both of the following are true:
- 1) a maximum operating sliding speed of each journal bearing is in the range 30 m/s to 50 m/s;
- and 2) a maximum specific load of each journal bearing is in the range 5 MPa to 25 MPa.
Dependencies are inferred from the claim text.