Engine accessory drives systems and methods
An accessory drive for an engine includes a power takeoff (PTO) configured to couple power from a rotating shaft of the engine and to convey the power through an opening in a housing of the engine. A gearbox is coupled to and configured to be driven by the PTO. The gearbox is disposed external to the housing and includes a planetary gear train. At least one engine accessory is coupled to and configured to be driven by the planetary gear train.
1. An accessory drive for an engine, the accessory drive comprising:
a power takeoff (PTO) configured to couple power from a rotating shaft of the engine and to convey the power through an opening in a housing of the engine;
a gearbox coupled to and configured to be driven by the PTO, the gearbox disposed external to the housing and including a planetary gear train comprising a sun gear, a planet carrier, a planet gear coupled to the planet carrier and disposed in driving engagement with the sun gear, and a ring gear disposed in driving engagement with the planet gear;
a first engine accessory coupled to and configured to be driven by a drive shaft disposed coaxial with the sun gear; and
a second engine accessory coupled to and configured to be driven by the ring gear, wherein the gearbox is configured to vary a first driven speed of the first engine accessory relative to a second driven speed of the second engine accessory in response to a load of at least one of the first engine accessory and/or the second engine accessory.
2. The accessory drive of claim 1 , wherein the engine comprises a turbofan engine.
3. The accessory drive of claim 1 , wherein the rotating shaft of the engine comprises a low pressure (LP) shaft or a high pressure (HP) shaft of the engine.
4. The accessory drive of claim 1 , further comprising a clutch and a brake disposed between the PTO and the rotating shaft.
5. The accessory drive of claim 1 ,
wherein, in response to the load of the first engine accessory, the sun gear is configured to reduce a rotational speed relative to a rotational speed of the ring gear.
6. The accessory drive of claim 1 , wherein the PTO comprises a tower shaft.
7. The accessory drive of claim 6 , wherein the tower shaft comprises an input end having at least one of a bevel gear, a crown gear, or a spur gear disposed thereon.
8. The accessory drive of claim 6 , wherein the tower shaft intersects the rotating shaft of the engine at an angle of about 0 to about 90 degrees.
9. The accessory drive of claim 6 , further comprising an angle shaft disposed between an output end of the tower shaft and an input end of the planetary gear train.
10. The accessory drive of claim 1 , wherein
the planetary gear train comprises a differential.
11. The accessory drive of claim 10 , wherein the differential comprises a bevel gear differential, and wherein at least one of the first engine accessory and/or the second engine accessory comprises an electrical generator, a pump, a compressor, or an engine starter.
12. The accessory drive of claim 11 , wherein the pump comprises a fuel pump, a hydraulic pump, or an oil pump.
13. A method for operating the accessory drive of claim 1 , the method comprising varying a rotational speed and/or a load of at least one engine accessory in response to the load of the at least one engine accessory during operation of the engine.
14. The method of claim 13 , wherein the accessories comprise a variable displacement pump, and wherein the varying comprises varying a position of a swash plate of the pump.
15. A method for driving at least one accessory of an engine, the method comprising:
receiving power from a rotating shaft of the engine and conveying it through an opening of a housing of the engine with a power takeoff (PTO);
driving a gearbox with the PTO, the gearbox disposed external to the housing and including a planetary gear train comprising a sun gear, a planet carrier, a planet gear coupled to the planet carrier and disposed in driving engagement with the sun gear, and a ring gear disposed in driving engagement with the planet gear;
varying a first driven speed of a first engine accessory coupled to and driven by a drive shaft disposed coaxial with the sun gear relative to a second driven speed of a second engine accessory coupled to and driven by the ring gear with the planetary gear train in response to a load of at least one of the first engine accessory and/or the second engine accessory.
16. The method of claim 15 , wherein the receiving of the power comprises:
driving a second gear on an input end of a first shaft with a first gear on the rotating engine shaft; and
extending an output end of the first shaft through the opening in the engine housing.
17. The method of claim 15 , wherein the varying of the first driven speed relative to the second driven speed comprises reducing a rotational speed of the sun gear relative to a rotational speed of the ring gear.
18. The method of claim 15 , wherein the driving of the gearbox comprises driving a fourth gear on an input end of the planetary gear train with a third gear on an output end of a first shaft.
19. The method of claim 18 , wherein the driving of the fourth gear comprises
driving the ring gear with the third gear.
20. The method of claim 19 , wherein the driving of the ring gear comprises:
driving a fifth gear on an input end of a second shaft with the third gear; and
driving the sun gear with a fifth gear on an output end of the second shaft.