Patent Description:
Gas turbine engines are known and typically include a fan delivering air into a bypass duct as bypass air and into a compressor as core air. The air is compressed and delivered into a combustor section where it is mixed with fuel and ignited. Products of the combustion pass downstream over turbine rotors, driving them to rotate. The gas turbine engines include multiple bearing compartments to house bearings that support rotating engine components. Additionally, the gas turbine engine includes a plurality of case portions that enclose the compressor, turbine, and combustor sections of the engine.

The bearing compartments and case portions typically include a plurality of axially aligned flanges that are fastened together. In one known configuration, a seal housing support flange and a carbon seal housing flange are bolted to a mid-turbine frame flange and bearing support housing. The seal housing support flange, the carbon seal housing flange, and mid-turbine frame flange have to be able to be disassembled from the bearing support housing. A first set of holes are formed in the seal housing support flange to receive jack screws that can separate the seal housing support flange from the carbon seal housing flange. A second set of holes are formed in the mid-turbine frame flange to receive jack screws that can separate the carbon seal housing flange and mid-turbine frame flange from the bearing support housing. The first and second sets of holes are circumferentially offset from each other. The first and second sets of holes are also circumferentially offset from alignment holes, clearance cut-outs for other components, and fastener holes that receive the fasteners to attach the flanges to each other.

All of these different holes and cut-outs that are formed on the flanges take up a significant amount of the flange face area, leaving limited radial and circumferential space to accommodate the disassembly features, e.g. jack screw holes. As engine sizes become more compact, real estate for packaging all of the critical design features becomes even more limited. Thus, it is challenging to provide disassembly solutions in the limited available space.

<CIT> discloses a case assembly comprising a first flange and a spot face in the first flange.

<CIT> discloses a method and system for use in facilitating relative movement between first and second components.

According to a first aspect of the invention, there is provided a gas turbine engine component as recited in claim <NUM>.

Further, optional, features are recited in each of claims <NUM> to <NUM>.

According to an aspect of the present invention, there is provided a gas turbine engine as recited in claim <NUM>.

According to an aspect of the present invention, there is provided a method as recited in claim <NUM>.

Further, optional, features are recited in each of claims, <NUM> and <NUM>.

The low speed spool <NUM> generally includes an inner shaft <NUM> that interconnects a first (or low) pressure compressor <NUM> and a first (or low) pressure turbine <NUM>. The inner shaft <NUM> is connected to a fan <NUM> through a speed change mechanism, which in exemplary gas turbine engine <NUM> is illustrated as a geared architecture <NUM> to drive the fan <NUM> at a lower speed than the low speed spool <NUM>.

Optionally, the engine could comprise a turbine engine that does not include a bypass.

The subject invention provides a simple and effective method of flange disassembly at various locations within the engine <NUM>. <FIG> shows flange assemblies <NUM> for a plurality of bearing compartments 38a, 38b, 38c, 38d that are located at various positions within the engine <NUM>. The case structure also include a plurality of flange assemblies <NUM> along the length of the engine <NUM>. Each of these flange assemblies <NUM>, <NUM> require disassembly features that allow the flanges to be easily separated from each other for maintenance and/or repair purposes. The subject invention provides a method and apparatus with disassembly features that provide for an inexpensive and simple disassembly process.

<FIG> shows one example where a first flange <NUM> is fixed to a second flange <NUM>. The first <NUM> and second <NUM> flanges are attached to a third flange <NUM>. The first <NUM>, second <NUM>, and third <NUM> flanges extend around the engine center axis A, and the first <NUM>, second <NUM>, and third <NUM> flanges are directly axially adjacent to each other in a direction along the engine center axis A. A plurality of first fastener holes <NUM> are formed in the first flange <NUM>, a plurality of second fastener holes <NUM> (<FIG>) are formed in the second flange <NUM>, and a plurality of third fastener holes <NUM> are formed in the third flange <NUM>. The first <NUM>, second <NUM>, and third <NUM> holes are concentric and axially aligned with each other such that fasteners <NUM> can be inserted through the aligned holes <NUM>, <NUM>, <NUM> to connect the first <NUM>, second <NUM>, and third <NUM> flanges together as shown in <FIG>.

<FIG> also shows that the first flange <NUM> includes a plurality of by-pass holes <NUM>, at least one locating pin P, and a plurality of clearance cut-outs <NUM> that are formed along an outer peripheral edge <NUM> of the first flange <NUM>. The by-pass holes <NUM> can be used as flow passages or as passages through which other components can be inserted. The clearance cut-outs <NUM> can be used for jumper tubes <NUM> or other components as known. The cut-outs <NUM> also provide for one or more locations for fasteners 76a that do not pass through the first flange <NUM>. Instead, these cut-outs <NUM> expose a portion of the second flange <NUM> such that the fasteners 76a only pass through the second <NUM> and third <NUM> fastener holes. Thus, the fasteners 76a do not pass through the first flange <NUM> and are only used to connect the second flange <NUM> to the third <NUM> flange.

The first fastener holes <NUM>, by-pass holes <NUM>, locating pin P, and cut-outs <NUM> are all circumferentially spaced apart from each other about the engine center axis A. As can be seen from <FIG>, there is very little circumferential and radial space to include disassembly features that can be used to disassemble the first <NUM> and second <NUM> flanges from the third flange <NUM>. The subject invention provides a disassembly feature that is efficiently packaged within the limited remaining circumferential and radial space. In the example shown, the first flange <NUM> comprises an intershaft seal support flange, the second flange <NUM> comprises a centering spring flange, and the third flange <NUM> comprises a bearing support flange; however, it should be understood that this is merely one example configuration and that other flange assemblies including more or less flanges could also utilize the subject invention.

In the example shown in <FIG>, the first flange <NUM> includes a plurality of first jack screw holes <NUM> (<FIG> and <FIG>) and the second flange <NUM> includes a plurality of second jack screw holes <NUM> (<FIG>) that are concentric with the plurality of first jack screw holes <NUM>. The first jack screw holes <NUM> are circumferentially spaced apart from each other about the engine center axis A. The first <NUM> and second <NUM> jack screw holes are circumferentially offset from the aligned first <NUM>, second <NUM>, and third <NUM> fastener holes. Each first jack screw hole <NUM> has a first center axis C1 (<FIG>). The second jack screw holes <NUM> are circumferentially spaced apart from each other about the engine center axis A. Each second jack screw hole <NUM> has a second center axis C2 (<FIG>). Each first jack screw hole <NUM> is axially aligned with one second jack screw hole <NUM> such that the first C1 and second C2 center axes are concentric as shown in <FIG>.

In one example, each first jack screw hole <NUM> has a first diameter D1 and each second jack screw hole <NUM> has a second diameter D2 that is greater than the first diameter D1 (<FIG>). The first <NUM> and second <NUM> jack screw holes are threaded holes. A first jack screw <NUM> threadably engages the first jack screw hole <NUM> and passes through a respective second jack screw hole <NUM> that is concentric with the first jack screw hole <NUM> to remove the first flange <NUM> from the second flange <NUM> (<FIG>). A distal end <NUM> of the first jack screw <NUM> reacts against the third flange <NUM> as the first jack screw <NUM> is screwed into the first jack screw hole <NUM> such that the first flange <NUM> can be axially pulled away from the second flange <NUM>.

Once the first flange <NUM> has been removed, a second jack screw <NUM> threadably engages the second jack screw hole <NUM> to remove the second flange <NUM> from the third flange <NUM> (<FIG>). A distal end <NUM> of the second jack screw <NUM> reacts against the third flange <NUM> as the second jack screw <NUM> is screwed into the second jack screw hole <NUM> such that the second flange <NUM> can be axially pulled away from the third flange <NUM>.

The first jack screw <NUM> has a first diameter S1 (<FIG>) and the second jack screw <NUM> has a second diameter S2 (<FIG>). In one example, the second jack screw <NUM> has a larger diameter S2 than the diameter S1 of the first jack screw <NUM>. This allows the smaller first jack screw <NUM> to pass through the larger diameter D2 of the second jack screw hole <NUM> unimpeded such that the distal end <NUM> of the first jack screw <NUM> can react against the third flange <NUM> without engaging the threads of the second jack screw hole <NUM>. Optionally, the reverse configuration could also be used where the first jack screw holes have a larger diameter than the second jack screw holes, which would also require the first jack screw to have a larger diameter than the second jack screw. In this configuration, a distal end of the larger first jack screw would react against a surface area that surrounds the smaller diameter second jack screw hole in the second flange.

A method of disassembling the flange assemblies <NUM>, <NUM> includes the following steps described below. As discussed above, the flange assemblies <NUM>, <NUM> include at least two flanges, and in the example shown include at least the first flange <NUM>, the second flange <NUM>, and the third flange <NUM> that are assembled together with the plurality of fasteners <NUM>. The first flange <NUM> has the first jack screw holes <NUM> and the second flange <NUM> has the second jack screw holes <NUM> that are concentric with the first jack screw holes <NUM>. In the example shown, there are six first <NUM> and second <NUM> concentric jack screw holes (<FIG>); however, it should be understood that there could be fewer or additional holes as needed. To disassemble the flange assemblies <NUM>, <NUM>, the fasteners <NUM> are removed. In the example shown, there are eight fasteners <NUM>; however, there could be fewer or additional fasteners <NUM> as needed.

Once the fasteners are removed, the first jack screws <NUM> are inserted into the first jack screw holes <NUM> to remove the first flange <NUM> from the second <NUM> and third <NUM> flanges. Once the first flange <NUM> has been removed, the second, larger jack screws <NUM> are inserted into the second jack screw holes <NUM> to remove the second flange <NUM> from the third flange <NUM>. Each first jack screw <NUM> hole has a smaller diameter S1 than the diameter S2 of the second jack screw <NUM> such that as the first jack screw <NUM> is threaded into the first jack screw hole <NUM>, the distal end <NUM> of the first jack screw <NUM> passes through the second jack screw hole <NUM> to react against the third flange <NUM> to remove the first flange <NUM> from the second flange <NUM> as the first jack screws <NUM> are threaded through the first jack screw holes <NUM>. The first jack screw hole <NUM> has a first screw diameter D1 that threadably matches the diameter S1 of the first jack screw <NUM>. The second jack screw <NUM> has a second screw diameter S2 that threadably matches the diameter D2 of the second jack screw hole <NUM>. The second diameter D2 is greater than the first diameter D1 such that as the second jack screw <NUM> is threaded into the second jack screw hole <NUM>, the distal end <NUM> of the second jack screw <NUM> reacts against the third flange <NUM> to remove the second flange <NUM> from the third flange <NUM> as the second jack screws <NUM> are threaded through the second jack screw holes <NUM>.

In one example, there may be a concern that when the first flange <NUM> is removed, the second flange <NUM>, which is tightly fit to the first flange <NUM>, may also come off with the first flange <NUM>. In order to address this potential issue, in one alternate embodiment one or more of the fasteners 76a are located in the cut-out <NUM> along the outer peripheral edge <NUM> of the first flange <NUM> such that these fasteners 76a do not pass through the first flange <NUM> and are only used to connect the second flange <NUM> to the third flange <NUM>. In this example configuration, all fasteners that extend through all three flanges <NUM>, <NUM>, <NUM> are first removed. This leaves one or more of the fasteners 76a to positively retain the second flange <NUM> to the third flange <NUM> as the first flange <NUM> is removed from the flange assembly <NUM>, <NUM>.

Once the main set of fasteners <NUM> are removed, the first jack screws <NUM> are then inserted into the first jack screw holes <NUM> and are rotated to pull the first flange <NUM> away from the second flange <NUM> as described above. The positive retention of the one or more fasteners 76a connecting only the second flange <NUM> to the third flange <NUM> ensures that the first flange <NUM> is removed without simultaneously removing the second flange <NUM> from the third flange <NUM>. Then, subsequent to removing the first flange <NUM> from the second flange <NUM>, the one or more fasteners 76a are removed from the second <NUM> and third <NUM> flanges. Then the second jack screws <NUM> are inserted into the second jack screw holes <NUM> to remove the second flange <NUM> from the third flange <NUM>.

The subject invention ensures a simple and effective method of flange disassembly that can be packaged and utilized on and within a set of flanges with limited space for disassembly features. The subject invention concentrically locates two sets of jack screw holes within axially adjacent flanges, which minimizes real estate consumed within each flange by disassembly features, e.g. jack screw holes. The concentrically located jack screw holes allow a first jack screw of a small diameter to pass through a larger diameter jack screw hole in a second flange located between a first flange with a threaded hole for the first jack screw and a retaining housing flange. Once the first flange has been removed using the smaller jack screws, the second flange can be removed from the retaining housing using larger diameter jack screws that are threaded into the larger sized jack screw holes in the second flange. Thus, the subject invention effectively stacks disassembly features on top of each other to allow for additional space within and through the flanges for other critical design features.

Claim 1:
A gas turbine engine component comprising:
a first flange (<NUM>);
a second flange (<NUM>) attached to the first flange (<NUM>);
a third flange (<NUM>) attached to the first and second flanges (<NUM>, <NUM>);
characterised by the first flange (<NUM>) including a plurality of first jack screw holes (<NUM>), the second flange (<NUM>) including a plurality of second jack screw holes (<NUM>) that are concentric with the plurality of first jack screw holes (<NUM>), wherein each first jack screw hole (<NUM>) has a first diameter and each second jack screw hole (<NUM>) has a second diameter that is different than the first diameter, the gas turbine engine component further comprising:
a first jack screw (<NUM>) configured to threadably engage one first jack screw hole (<NUM>) and to pass through a respective second jack screw hole (<NUM>) that is concentric with the one first jack screw hole (<NUM>) to remove the first flange (<NUM>) from the second flange (<NUM>); and
a second jack screw (<NUM>) configured to threadably engage one second jack screw hole (<NUM>) to remove the second flange (<NUM>) from the third flange (<NUM>),
wherein the second diameter is greater than the first diameter, and wherein the second jack screw (<NUM>) has a larger diameter than the first jack screw (<NUM>).