Pump sleeve for integrated drive generator

A pump sleeve for an inversion pump in an integrated drive generator has a pump sleeve body extending between a first end and a second end, the first end being at a location adjacent an enlarged endplate. The body extends to the second end with a generally cylindrical body portion having a bore of an inner diameter from the first end to the second end, and between the first and second ends for a distance. A ratio of the first distance to the inner diameter being is 1.8 and 2.0. In addition, an integrated drive generator is disclosed as is a method of replacing an accessory drive gear in an integrated drive generator.

BACKGROUND

This application relates to a pump sleeve for an inversion pump for use in an integrated drive generator.

Integrated drive generators are known and often utilized in aircraft. As known, a gas turbine engine on the aircraft provides a drive input into a generator input shaft. The generator typically includes a disconnect shaft that can transmit the input into a gear differential. The gear differential selectively drives a main generator to provide electric power for various uses on the aircraft.

It is desirable that the generated power be of a desired constant frequency. However, the speed from the input shaft will vary during operation of the gas turbine engine. This would result in variable frequency.

Integrated drive generators are provided with speed trimming hydraulic units. Gears associated with the differential and, in particular, a ring gear portion, provide rotation from the differential back into the trimming unit. A carrier also rotates another portion of the trimming unit. The trimming unit is operable to result in the output speed of the differential being effectively constant, such that electric power of a desirable frequency is generated.

The generator is mounted between two housing portions and a seal plate is mounted between the two housing portions.

In addition, various accessory systems, such as various pumps, are driven by the carrier of the differential through an accessory drive gear.

In addition, various accessory systems, such as various pumps, are driven by differential output ring gear through an accessory drive gear.

One of the pumps is an inversion pump and a pump sleeve for the inversion pump raises design challenges.

SUMMARY

A pump sleeve for an inversion pump in an integrated drive generator has a pump sleeve body extending between a first end and a second end, the first end being at a location adjacent an enlarged endplate. The body extends to the second end with a generally cylindrical body portion having a bore of an inner diameter from the first end to the second end, and extending between the first and second ends for a distance. A ratio of the first distance to the inner diameter is between 1.8 and 2.0.

In addition, an integrated drive generator is disclosed as is a method of replacing an accessory drive gear in an integrated drive generator.

DETAILED DESCRIPTION

FIG. 1shows an integrated drive generator20. As shown, housing portions18and19surround the integrated drive generator and a seal plate17sits between the housing portions18and19.

A gas turbine engine22may drive an input shaft23which selectively drives a disconnect assembly26. The disconnect assembly26, in turn, drives a carrier shaft28, which drives a carrier in a gear differential30.

As the carrier shaft28rotates, planet gears36and38are caused to rotate. Gears38have a gear interface42with a first ring gear portion40. Gears36have a gear interface48with a second ring gear portion46.

Ring gear portion40has a gear interface50with a main generator drive gear52. When drive gear52is driven to rotate, it rotates a rotor56associated with a stator58of the main generator as well as an exciter rotor60. Electric power is generated for a use62, as known.

It is desirable that the frequency of the generated electric power be at a desired frequency. This requires the input speed to gear52to be relatively constant and at the desired speed. As such, the speed of the input shaft23is added to the speed of the speed trimmer66to result in a constant input speed to gear52.

A gear15that is part of the carrier has a gear interface16with a gear13driving a shaft14also within the speed trimmer.

As known, the speed trimmer66includes a variable unit72and a fixed unit76. The units72and76may each be provided with a plurality of pistons and a swash plate arrangement. If the input speed of the gear13is too high, the speed of the gear52will also be too high, and hence, the speed trimmer66acts to lower the speed of the trim gear46which will drop the speed of gear52. On the other hand, if the input speed is too low, the speed trimmer will increase the trim gear speed and the speed seen by gear52will increase.

In essence, the variable unit72receives an input through gear13that is proportional to the speed of the input shaft23. The variable unit72also receives a control input from a control monitoring the speed of the generator rotor56. The position of the swash plate in the variable unit72is changed to in turn change the speed and direction of the fixed unit76. The fixed unit76can change the speed, and direction of rotation of the shaft70, and this then provides control back through the trim ring gear46to change the speed reaching the generator. In this manner, the speed trimmer66results in the frequency generated by the generator being closer to constant, and at the desired frequency.

A permanent magnet generator32rotates with the ring gear40.

An accessory drive shaft29rotates with the ring gear40and drives a plurality of accessory gears31.

The operation of the integrated drive generator20is generally as known in the art. A worker of ordinary skill would recognize that the desired frequency and speed at use62would dictate a number of design functions.

FIG. 2shows the accessory drive gear29. The accessory drive gear29drives a pair of driven gears99. These driven gears were shown schematically as gear31inFIG. 1. One gear99drives a second gear102which, in turn, drives a governor104. The gear99also drives an inversion pump100through a shaft101. The second gear99drives a deaerator through gear108, as well as a charge pump110and a scavenge pump112.

The inversion pump100is illustrated inFIG. 3A. A pump shaft202is driven by gear99, and carries a plurality of vanes204. The vanes rotate within a cam206having an inner cam surface208. An outer pump sleeve210is also illustrated.

As shown in the exploded view ofFIG. 3B, the pump100includes the pump shaft202, the vanes204, the cam206and the sleeve210. As can be seen, the sleeve210has opposed windows216and218which provide inlet and outlet ports into the pump200. The cam206has mating windows316and318. Bearings220and226are positioned at each end of the cam.

A plurality of Belleville spring washers,222, provides a bias force. As shown, the cam206includes a keyway224and the sleeve210includes a mating keyway240(not shown). The key228locks the two together to prevent rotation.

The pump sleeve210is illustrated inFIG. 4A. The windows216and218are shown. Window216extends between circumferential ends211and213. In one embodiment, the window extended for 100 degrees. In embodiments, the window212may extend over between 90 and 110 degrees.

The window214extends between ends215and217. In one embodiment, the window extended for 109 degrees. In embodiments, the window may extend between 99 and 119 degrees.

FIG. 4Bshows another view of the pump sleeve210. An enlarged endplate230is formed at one end. A cylindrical portion236extends from an end232immediately after, or adjacent the endplate230to the end234. The cylindrical portion236extends for a distance d1between first and second ends232and234. The windows216and218are shown to extend for an axial distance d2measured parallel to central axis C of the sleeve.

In one embodiment, a diameter D is an inner diameter of a bore240as can be seen inFIG. 4C.

The distance d1, in one embodiment, was 2.605 inches (6.617 centimeters). The distance d2, in one embodiment, was 0.832 inch (2.113 centimeters). The diameter, in one embodiment, was 1.3754 inches (3.493 centimeters). These dimensions can be taken as being within +/−0.010 inch (0.025 cm).

In embodiments, a ratio of the distance d2to the diameter D is between 0.5 and 0.7. A ratio of the distance d1to D is between 1.8 and 2.0. A ratio of d2to d1is between 0.25 and 0.39.

A method of replacing a pump sleeve for an inversion pump in an integrated drive generator includes the steps of removing an existing pump sleeve from an inversion pump in an integrated drive generator. The integrated drive generator has an input shaft and a gear differential including a carrier shaft to be driven by the input shaft and a ring gear for driving a generator. The ring gear is also connected to drive an accessory drive gear. The accessory drive gear is connected to drive at least the inversion pump, which includes a driven shaft driven by the accessory drive gear, a plurality of vanes, a cam and the existing pump sleeve. The existing pump sleeve is replaced with a replacement pump sleeve including a pump sleeve body extending between a first end and a second end, the first end being at a location adjacent an enlarged endplate. The body extends to the second end with a generally cylindrical body portion having a bore with an inner diameter from the first end to the second end, and extends between the first and second ends for a distance. A ratio of the first distance to the inner diameter being between 1.8 and 2.0.