Integrated drive generator housing

Abstract

A method of assembling an integrated drive generator includes the steps of providing a bore in a center housing portion, pressing a bearing liner into the bore, with a portion of the bearing liner extending proud of a surface of the center plate, and machining the surface around and adjacent to the bearing liner to provide a machined surface parallel to the surface.

Claims

1. A method of assembling an integrated drive generator, comprising steps of: providing a bore in a center housing portion; pressing a bearing liner into the bore, with a portion of the bearing liner extending proud of a first surface of the center housing portion; and machining the first surface around and adjacent to the bearing liner subsequent to performing the pressing step to form a machined surface parallel to the first surface.

2. The method according to claim 1, further comprising the steps of: securing a generator housing portion, the center housing portion and an input housing portions to one another, the center housing portion sealed relative to the generator housing portion and the input housing portions with seal plates; mounting a hydraulic unit to the center housing portion; and wherein the center housing portion includes second surface parallel to the first surface, and the machined surface is parallel to and recessed into the first surface in an area of the hydraulic unit, wherein the hydraulic unit includes a shaft supported by a bearing in the center housing portion, the machined surface surrounding the bearing, wherein the bearing includes the bearing liner extending proud of the machined surface.

3. The method according to claim 2, wherein the bearing is a roller bearing.

4. The method according to claim 1, wherein the bearing liner is in an interference fit in the bore in the center housing portion.

5. The method according to claim 1, wherein the bearing liner includes first and second flanges opposite one another, the second flange engaging the second surface, and the first flange proud of the first surface and engaging the bearing.

6. The method according to claim 1, wherein the machined surface provides a lip circumscribing the bearing liner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

(2) FIG. 1 is a highly schematic view of a generator system.

(3) FIG. 2 is a cross-sectional schematic view of an example integrated drive generator.

(4) FIG. 3 is a schematic perspective view of a generator, a hydraulic unit and a differential assembly of the integrated drive generator shown in FIG. 2.

(5) FIG. 4 is a cross-sectional view through the hydraulic unit.

(6) FIG. 5 is an enlarged cross-sectional view of in an area of a bearing supporting a hydraulic unit shaft relative to a center housing portion.

(7) FIG. 6 is an enlarged cross-sectional view of the hydraulic unit mounted to the center housing portion.

DETAILED DESCRIPTION

(8) An example generator system 10 is schematically illustrated in FIG. 1. The system 10 includes a gas turbine engine 12 that provides rotational drive to an integrated drive generator (IDG) 16 through an accessory drive gearbox 14 mounted on the gas turbine engine 12. The accessory drive gearbox 14 is coupled to a spool of the engine 12, and the speed of the spool varies throughout engine operation.

(9) Referring to FIGS. 2 and 3, an example IDG 16 is illustrated. In the example, the IDG 16 includes a housing 18 having generator, center and input housing portions 20, 22, 24 secured to one another. A generator 40 is arranged in the generator housing portion 20. Seal plates 23 are provided on either side of the center housing 22 to seal the center housing 22 relative to the generator and input housing portions 20, 24.

(10) An input shaft 26 receives rotational drive from the accessory drive gearbox 14. The rotational speed of the input shaft 26 varies depending upon the operation of the engine 12. To this end, as a result, a hydraulic unit 32 cooperates with the differential assembly 28 to convert the variable rotational speed from the input shaft 26 to provide a fixed rotational output speed to the generator 40.

(11) The input shaft 26 rotationally drives a differential input gear 30 that is coupled to a hydraulic input gear 34 of the hydraulic unit 32. The differential input gear 30 is operatively coupled to the input shaft 26 by the disconnect assembly 27. The hydraulic output gear 36 is coupled to a differential speed trim gear 38. The hydraulic unit 32 increases or decreases the rotational speed provided to the differential unit 28 from the hydraulic input gear 34 to provide a fixed rotational output speed, such as a 12,000 rpm speed. The variable rotational speed of the differential input gear 30 combines with the speed of the differential speed trim gear 38 to provide a fixed rotational speed to a gear input shaft 42.

(12) In the example, a gear train 44 cooperates with the generator input shaft 42, which rotates at a constant speed to rotationally drive a charge pump 46, deaerator 48, main scavenge pump 50, inversion pump 52 and generator scavenge pump 54. Thus, these components may be designed efficiently to operate at a fixed speed.

(13) Referring to FIG. 4, the hydraulic unit 32 includes a can 60 that houses and provides structural support for the hydraulic unit components. Fixed and variable speed shafts 62, 64 are arranged coaxially with and nested relative to one another on one side of the hydraulic unit 32. The hydraulic input gear 34 is provided by the variable speed shaft 64, and the hydraulic output gear 36 is provided by the trim speed shaft 62.

(14) A speed change shaft 72 is also arranged within the can 60 and is coaxial with the trim and variable speed shafts 62, 64. A pump plate 66 separates first and second pumping assemblies 68, 70, which each include a wobbler and pistons. The pumping assemblies cooperate with one another to increase or decrease the rotational speed of the trim speed shaft 62.

(15) A first bearing 74 supports the trim speed shaft 62 relative to the can 60, and a second bearing 76 supports the other end of the trim speed shaft 62 relative to the pump plate 66. Another second bearing 76 supports the speed change shaft 72 relative to the pump plate 66, and a third bearing 78 supports the other end of the speed change shaft 72 relative to the center housing 22. A fourth bearing 79 supports the variable speed shaft 64 relative to the input housing 24.

(16) Referring to FIGS. 4 and 5, the center housing portion 22 includes a bore 80 that receives the third bearing 78. A bearing liner 82, which may be steel, is press-fit into the bore 80. The bearing liner 82 includes first and second flanges 84, 86 adjoined by a wall 88 that is received in the bore 80 to provide the press-fit. It is desirable to press-fit the bearing liner 82 into the bore 80 prior to machining, since press-fitting may distort the magnesium center housing portion 22. The center housing portion 22 includes first and second surfaces 98, 100 that are laterally spaced apart from one another. The first and second surfaces 98, 100 may be provided by an initial machining operation that may provide sufficiently flat surfaces for adequate sealing of the seal plates 23. The second flange 86 abuts the second surface 100 to limit the installation depth of the bearing liner 82 during press-fitting.

(17) The first flange 84 extends proud or beyond the first surface 98, which is necessary to accommodate the width of the third bearing 78. The third bearing 78 includes an outer race 90 received by the bearing liner 82 in abutting relationship with the first flange 84. Rollers 92 are spaced circumferentially about an inner race 96, which is provided by the speed change shaft 72, and engage the outer and inner races 90, 96. The circumferential spacing of rollers 92 are maintained by a cage 94.

(18) The center housing portion 22 is machined to a thinner width than provided by the first and second surfaces 98, 100. This may enable a longer hydraulic unit to be accommodated in the same sized housing envelope as previously used IDGs. However, desired flatness of the center housing portion 22 must be maintained to ensure proper sealing of the center housing portion 22 relative to the generator and input housing portions 20, 24. To this end, the first surface 98 is machined, for example, using a milling operation, to provide a machined surface 102 that is parallel with the second surface 100. The bearing liner 82 is installed before machining.

(19) The can 60 includes a flange 106 that is secured to the center housing portion 22. The flange 106 includes holes 108 aligned with holes 110 in the center housing portion 22. Fasteners 112 are received by the holes 108, 110 and secure the flange 106 to the center housing portion 22. A machined surface 114, provided for example using a milling operation, is recessed into the second surface 100 to accommodate the longer hydraulic unit and provide a first lateral thickness T1. The first lateral thickness T1 is provided between the first surface 98 and the machined surface 114, which are parallel to one another. A second lateral thickness T2 is provided between the first and second surfaces 98, 100. The ratio of the second lateral thickness T2 to the first lateral thickness T1 is 1.05.

(20) Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.