초록 ▼

A gas turbine engine has a casing component, such as a mid turbine frame system, which includes an outer case surrounding a spoke or strut casing. Load transfer spokes of the spoke casing are detachably connected to the outer case and radially extend between the outer case and an inner case of the s

A gas turbine engine has a casing component, such as a mid turbine frame system, which includes an outer case surrounding a spoke or strut casing. Load transfer spokes of the spoke casing are detachably connected to the outer case and radially extend between the outer case and an inner case of the spoke casing. A bearing housing is supported by the inner case of the spoke casing. An arrangement for radially centring the bearing within the outer case is provided, the arrangement including at least three radial locators mounted to the outer case.

대표청구항 ▼

1. A method of assembly for a mid turbine frame of a gas turbine engine, the method comprising the steps of: a) assembling a sub-assembly including an annular bearing housing, an annular spoke casing and an annular interturbine duct, at least three spokes of the spoke casing radially outwardly exten

1. A method of assembly for a mid turbine frame of a gas turbine engine, the method comprising the steps of: a) assembling a sub-assembly including an annular bearing housing, an annular spoke casing and an annular interturbine duct, at least three spokes of the spoke casing radially outwardly extending through respective hollow struts of the annular interturbine duct and radially projecting from the annular interturbine duct;b) inserting the sub-assembly within an outer case; andc) adjusting at least three radial locators in respective radial positions relative to the outer case, the radial locators being adjustably attached to the outer case and circumferentially aligned with respective spokes, the respective radial locators having an end in contact with an end surface of the respective spokes, the end surface being substantially normal to a radial axis of the respective spokes, the radial locators adjusted to adjust a radial gap between the end surfaces of the spokes and the outer case to thereby center the annular bearing housing within the outer case. 2. The assembly method as defined in claim 1 further comprising a step of securing the spokes to the outer case using a plurality of fasteners after the annular bearing housing is centered within the outer case. 3. The assembly method as defined in claim 1 further comprising a step of locking the respective radial locators in position after the annular bearing housing is centered within the outer case. 4. The assembly method as defined in claim 1 wherein the adjustment of the respective radial locators is conducted by selectively rotating the respective radial locators through threaded holes defined in the outer case to change a radial length protrusion of the respective radial locators into the outer case. 5. The assembly method as defined in claim 1 further comprising a step of circumferentially aligning the outer ends of the spokes with the respective radial locators prior to step (c). 6. The assembly method as defined in claim 1 further comprising a step of using a fixture to centre the bearing housing of the sub-assembly relative to the outer case prior to the step of adjusting the radial locators. 7. A method of assembly for a mid turbine frame of a gas turbine engine, the method comprising the steps of: a) providing a mid turbine frame sub-assembly, the sub-assembly including at least an inner annular casing supporting at least one bearing and having at least three struts extending radially outwardly therefrom, the sub-assembly defining a portion of an engine gas path, the struts extending across the gas path;b) inserting the sub-assembly within an outer annular case of the mid turbine frame, a radial gap provided between an outer periphery of the sub-assembly and the outer case, the outer case having at least three radial locators threaded through the engine case and disposed around a circumference of the outer case, the radial locators having a terminal end extending radially inwardly of the outer case; andc) threadingly adjusting the radial locators relative to the outer annular case until each terminal end abuts the outer periphery of the sub-assembly, the respective terminal ends being in contact with an end surface of the respective struts, the end surface being substantially normal to a radial axis of the respective struts, the radial locators individually adjusted to adjust the radial gap between the sub-assembly and the outer case to centre the at least one bearing relative to the outer case. 8. The assembly method as defined in claim 7 further comprising a step of securing the sub-assembly to the outer case by inserting a plurality of fasteners through the outer case to engage the sub-assembly and secure it in place after the sub-assembly is centred within the outer case. 9. The assembly method as defined in claim 7 further comprising a step of locking the respective radial locators in position after the sub-assembly is centred within the outer case. 10. The assembly method as defined in claim 7 wherein the adjustment of the respective radial locators is conducted by selectively rotating the respective radial locators through threaded holes defined in the outer case to change a radial length the respective terminal ends of the radial locators protrude radially into the outer case. 11. The assembly method as defined in claim 7 further comprising a step of circumferentially aligning the sub-assembly with the outer case so that outer ends of the struts, which extend radially and outwardly from the sub-assembly, are aligned with respective radial locators prior to step (c), the radial locators thereby abutting the struts. 12. The assembly method as defined in claim 11 wherein the outer periphery defined by the struts is substantially normal to the radial locator central axis. 13. The assembly method as defined in claim 7 further comprising a step of mounting the sub-assembly and the outer case in a fixture, the fixture positioning the sub-assembly so that the at least one bearing is centred relative to the outer case, and wherein said step is performed prior to the step of threadingly adjusting. 14. A gas turbine engine having a mid turbine frame, the mid turbine frame comprising: an annular outer case connected to and forming a portion of an engine casing;a spoke casing including an annular inner case disposed within the outer case, the spoke casing having at least three load transfer spokes affixed to the inner case and extending radially outwardly therefrom, an outer end of the respective load transfer spokes being detachably secured to the outer case, a radial gap provided between the outer ends of the load transfer spokes and the outer case, the inner case supporting at least one bearing disposed around an engine main shaft; anda radial locator radially adjustably attached to the outer case and having an end in contact with an end surface of at least three of the at least three load transfer spokes, the end surface being substantially normal to a radial axis of the respective load transfer spokes, a radial inward extent of the locator being adjustable relative to the outer case to vary a radial position of an outward extent of the corresponding spoke for radially positioning the spoke casing within the outer case. 15. The gas turbine engine as defined in claim 14 wherein the end surface of each load transfer spoke is substantially normal to a respective radial locator axis. 16. The engine as defined in claim 14 wherein the respective load transfer spokes are connected to the outer case by a plurality of fasteners having central axes parallel to the radial locator. 17. The engine as defined in claim 14 wherein the outer case comprises a plurality of support bosses for receiving spokes, each of the support bosses having a base substantially normal to the radial axis of the respective load transfer spoke. 18. The engine as defined in claim 17 wherein each of the radial locators comprises a threaded stem received through a threaded opening defined in the outer case. 19. The engine as defined in claim 17 wherein each of the radial locators further comprises a locking device for locking the radial locator in a selected radial position with respect to the outer case. 20. The engine as defined in claim 14 wherein at least one of the radial locators defines a radial passage extending therethrough and aligning with a radial opening defined in the respective load transfer spokes, said radial passage extending through the respective load transfer spoke to the inner case.