US 12,297,745 B2
Gearboxes for aircraft gas turbine engines
Mark Spruce, Derby (GB)
Assigned to ROLLS-ROYCE plc, London (GB)
Filed by ROLLS-ROYCE plc, London (GB)
Filed on Feb. 27, 2024, as Appl. No. 18/588,409.
Application 18/588,409 is a continuation of application No. 18/219,967, filed on Jul. 10, 2023, granted, now 11,946,382.
Application 18/219,967 is a continuation of application No. 17/863,836, filed on Jul. 13, 2022, granted, now 11,739,660.
Application 17/863,836 is a continuation of application No. 17/205,870, filed on Mar. 18, 2021, granted, now 11,421,552, issued on Aug. 23, 2022.
Application 17/205,870 is a continuation of application No. 16/990,302, filed on Aug. 11, 2020, granted, now 10,982,563, issued on Apr. 20, 2021.
Claims priority of application No. 2005025 (GB), filed on Apr. 6, 2020.
Prior Publication US 2024/0200467 A1, Jun. 20, 2024
Int. Cl. F01D 25/18 (2006.01); F01D 25/16 (2006.01); F02C 3/113 (2006.01); F02C 7/06 (2006.01); F02C 7/36 (2006.01); F02K 3/06 (2006.01); F16H 57/04 (2010.01); F16H 57/08 (2006.01)
CPC F01D 25/18 (2013.01) [F01D 25/166 (2013.01); F02C 3/113 (2013.01); F02C 7/06 (2013.01); F02C 7/36 (2013.01); F02K 3/06 (2013.01); F16H 57/0469 (2013.01); F16H 57/0479 (2013.01); F05D 2220/323 (2013.01); F05D 2220/36 (2013.01); F05D 2260/40311 (2013.01); F16H 2057/085 (2013.01)] 20 Claims
OG exemplary drawing
 
1. 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:
a ratio of a length, L, of the internal and external sliding surfaces to a diameter, D, of each journal bearing is greater than 0.5;
a pitch circle diameter of the ring gear is no greater than 1200 mm; and
a diametral clearance of each journal bearing, defined by the difference between the diameter of the internal sliding on the planet gear and the diameter of the external sliding surface on the pin, is between 120 um and 600 um.