Patent Description:
A gas turbine engine may include a shaft rotatably mounted to a housing by a bushing. The shaft may rotate within the bushing such that the shaft and the bushing form a journal bearing. Various types and configurations of journal bearing bushings are known in the art. While these known journal bearing bushings have various benefits, there is still room in the art for improvement. There is a need in the art therefore for an improved bushing for rotatably mounting a rotating structure such as a shaft to a stationary structure such as a housing.

<CIT> discloses a turbocharger for an internal combustion engine.

<CIT> discloses a turbocharger impeller.

<CIT> discloses a turbocharger impeller screwed onto a shaft with an arrangement for accommodating thermal dilatation.

<CIT> discloses a face seal assembly for a variable turbine geometry turbocharger.

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

Optionally, and in accordance with any of the above, the stationary structure material may be or otherwise include aluminum.

Optionally, and in accordance with any of the above, the stationary structure material may be or otherwise include magnesium.

Optionally, and in accordance with any of the above, the stainless steel may be or otherwise include <NUM> series stainless steel.

Optionally, and in accordance with any of the above, the stainless steel may be or otherwise include one of: <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; or <NUM> stainless steel.

Optionally, and in accordance with any of the above, the stainless steel may be or otherwise include one of: <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; or <NUM> stainless steel.

Optionally, and in accordance with any of the above, the bearing material may be configured from or otherwise include bronze, where the bronze includes the copper.

Optionally, and in accordance with any of the above, the bronze may be or otherwise include leaded bronze.

Optionally, and in accordance with any of the above, the bearing material may contact the mount material.

Optionally, and in accordance with any of the above, the bushing may also include a sleeve radially between the mount and the bearing. The sleeve may be configured from or otherwise include sleeve material with a coefficient of thermal expansion between <NUM>µin/in-°F (<NUM>/m-°C) and <NUM>µin/in-°F (<NUM>/m-°C). The sleeve material may contact the mount material and the bearing material.

Optionally, and in accordance with any of the above, the mount may include a base and a flange. The base may be disposed within an aperture of the stationary structure and may radially contact the stationary structure. The flange may project radially out from the base and may axially engage the stationary structure.

Optionally, and in accordance with any of the above, the rotating structure may be configured as or otherwise include a shaft.

Optionally, and in accordance with any of the above, the rotating structure may be configured as or otherwise include a gear.

<FIG> illustrates an assembly <NUM> for a gas turbine engine. This gas turbine engine may be included within an aircraft propulsion system. The gas turbine engine, for example, may be configured as a turbofan gas turbine engine, a turboshaft gas turbine engine, a turboprop gas turbine engine or a turboshaft gas turbine engine. The gas turbine engine may alternatively be included within a power generation system. The gas turbine engine, for example, may be configured as an auxiliary power unit (APU) or an industrial gas turbine engine. The engine assembly <NUM> of the present disclosure, however, is not limited to any particular gas turbine engine type or configuration.

The engine assembly <NUM> of <FIG> includes a rotating structure <NUM> and a stationary structure <NUM>. This engine assembly <NUM> also includes a multi-section / multi-material bushing <NUM> (e.g., a journal bearing bushing) rotatably mounting the rotating structure <NUM> to the stationary structure <NUM>.

The rotating structure <NUM> extends axially along an axial centerline <NUM> to an axial end <NUM> of the rotating structure <NUM>. The rotating structure <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>. The rotating structure <NUM> extends radially outward (e.g., away from the axial centerline <NUM>) to a radial outer side <NUM> of the rotating structure <NUM>.

The rotating structure <NUM> is rotatable about the axial centerline <NUM>; e.g., a rotational axis. This rotating structure <NUM> may be configured as a rotor for an apparatus within the gas turbine engine such as a geartrain <NUM>. The rotating structure <NUM> of <FIG>, for example, includes a shaft <NUM> and another rotating element <NUM> such as a gear. The rotating element <NUM> is connected to (e.g., formed integral with or otherwise attached to) and rotatable with the shaft <NUM>. The shaft <NUM> of <FIG> projects axially out from and/or away from the rotating element <NUM> along the axial centerline <NUM> to the rotating structure end <NUM>. The shaft <NUM> of <FIG> also projects radially out to the rotating structure outer side <NUM>. The present disclosure, however, is not limited to such an exemplary rotating structure configuration. The rotating structure <NUM>, for example, may alternatively be configured as or otherwise include a sleeve or another component mounted on or otherwise connected to the shaft <NUM> and/or the rotating element <NUM>. Furthermore, the present disclosure is not limited to geartrain applications. The rotating structure <NUM>, for example, may also or alternatively include or be rotatably coupled to various other rotating components within the gas turbine engine besides a gear; e.g., a bladed rotor, etc..

The rotating structure <NUM> is constructed from or otherwise includes rotating structure material. This rotating structure material is a metal such as a high strength, low alloy steel; e.g., AISI <NUM>, AISI <NUM> and AISI <NUM>-22A. The rotating structure material may be selected to have a coefficient of thermal expansion between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C); e.g., <NUM>µin/in-°F (~<NUM>/m-°C) for AISI <NUM>, <NUM>µin/in-°F (~<NUM>/m-°C) for AISI <NUM>, or <NUM>µin/in-°F (~<NUM>/m-°C) for AISI <NUM>-22A. The coefficient of thermal expansion may be measured at <NUM>°F (<NUM>).

The stationary structure <NUM> extends axially along the axial centerline <NUM> between and to an axial first side <NUM> of the stationary structure <NUM> and an axial second side <NUM> of the stationary structure <NUM>. The stationary structure <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>. The stationary structure <NUM> extends radially inwards (e.g., towards the axial centerline <NUM>) to a radial inner side <NUM> of the stationary structure <NUM>. This stationary structure inner side <NUM> forms an aperture <NUM> (e.g., a bore) within the stationary structure <NUM>. The stationary structure aperture <NUM> of <FIG> extends axially through the stationary structure <NUM> between the stationary structure first side <NUM> and the stationary structure second side <NUM>. This stationary structure aperture <NUM> receives the rotating structure <NUM>. The rotating structure <NUM> of <FIG> and its shaft <NUM>, for example, project axially along the axial centerline <NUM> into (e.g., through) the stationary structure aperture <NUM>. The stationary structure <NUM> of <FIG> may thereby circumscribe the rotating structure <NUM> and its shaft <NUM>.

The stationary structure <NUM> is configured as a support for the rotating structure <NUM> and the bushing <NUM>. The stationary structure <NUM> may also be configured as a housing for the rotating structure <NUM> and/or one or more the other components of the engine assembly <NUM>. The stationary structure <NUM>, for example, may be configured as a geartrain housing with a leg or wall that supports the rotating structure <NUM> through the bushing <NUM> as described below. The present disclosure, however, is not limited to such an exemplary stationary structure configuration.

The stationary structure <NUM> is constructed from or otherwise includes stationary structure material. This stationary structure material is a high thermal expansion and/or lightweight metal such as aluminum (Al), magnesium (Mg), and/or an alloy thereof. The stationary structure material is selected to have a coefficient of thermal expansion between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C); e.g., between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C), between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C), between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C), etc. For example, the aluminum stationary structure material may be cast C355/<NUM> (<NUM>µin/in-°F (~<NUM>/m-°C)), A357/F357 (<NUM>µin/in-°F (<NUM>/m-°C)) or A356/<NUM> (<NUM>µin/in-°F (<NUM>/m-°C). The magnesium stationary structure material may be cast ZE41A (<NUM>µin/in-°F (<NUM>/m-°C)), WE43A (<NUM>µin/in-°F (<NUM>/m-°C)) or EV31A (<NUM>µin/in-°F (<NUM>/m-°C)). The coefficient of thermal expansion is measured at <NUM>°F (<NUM>).

Referring to <FIG>, the bushing <NUM> extends axially along the axial centerline <NUM> between and to an axial first side <NUM> of the bushing <NUM> and an axial second side <NUM> of the bushing <NUM>. The bushing <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>; e.g., providing the bushing <NUM> with an annular body. The bushing <NUM> extends radially between and to a radial inner side <NUM> of the bushing <NUM> and a radial outer side <NUM> of the bushing <NUM>. The bushing <NUM> of <FIG> includes a bushing mount <NUM> and a bushing bearing <NUM>.

The mount <NUM> of <FIG> includes a mount base <NUM> and a mount flange <NUM>; e.g., an annular rim. The base <NUM> extends axially along the axial centerline <NUM> between and to an axial first side <NUM> of the base <NUM> and the bushing second side <NUM>, where the base first side <NUM> may be recessed axially inward from the bushing first side <NUM>. The base <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>. The base <NUM> extends radially between and to a radial inner side <NUM> of the mount <NUM> and a radial outer side <NUM> of the base <NUM>. The flange <NUM> is connected to (e.g., formed integral with or otherwise attached to) the base <NUM> at (e.g., on, adjacent or proximate) the bushing first side <NUM>. The flange <NUM> of <FIG> projects radially out from the base <NUM> and its base outer side <NUM> to a radial distal end <NUM> of the flange <NUM>; here, the bushing outer side <NUM>. The flange <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>. The flange <NUM> extends axially along the axial centerline <NUM> and the base <NUM> between and to the bushing first side <NUM> and an axial second side <NUM> of the flange <NUM>, where the flange second side <NUM> is recessed axially inward from the bushing second side <NUM>.

The base <NUM> and the flange <NUM> of <FIG> are configured to provide the mount <NUM> with a receptacle <NUM>; e.g., an annular notch or groove. This receptacle <NUM> projects axially into the bushing <NUM> from the bushing second side <NUM> to the flange second side <NUM>. The receptacle <NUM> projects radially inward into the bushing <NUM> from the bushing outer side <NUM> to the base outer side <NUM>. The receptacle <NUM> also extends circumferentially about (e.g., completely around) the axial centerline <NUM>.

The mount <NUM> is constructed from or otherwise includes mount material. This mount material is stainless steel (ss) - a high thermal expansion metal. This stainless steel may be <NUM> series stainless steel such as, but not limited to: <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; or <NUM> stainless steel. The stainless steel may alternatively be <NUM> stainless steel such as, but not limited to: <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; <NUM> stainless steel; or <NUM> stainless steel. The mount material is selected to have a coefficient of thermal expansion between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C); e.g., between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C), between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C), etc. The coefficient of thermal expansion is measured at <NUM>°F (<NUM>).

The bearing <NUM> extends axially along the axial centerline <NUM> between and to an axial first side <NUM> of the bearing <NUM> and the bushing second side <NUM>, where the bearing first side <NUM> may be recessed axially inward from the bushing first side <NUM> and/or axially aligned with the base first side <NUM>. The bearing <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>. The bearing <NUM> extends radially between and to the bushing inner side <NUM> and a radial outer side <NUM> of the bearing <NUM>.

The bearing <NUM> is constructed from or otherwise includes bearing material. This bearing material is a high strength, low friction metal that includes copper; e.g., a copper alloy. The bearing material, for example, may be bronze such as, but not limited to, leaded bronze. The bearing material may have a coefficient of thermal expansion between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C); e.g., <NUM>µin/in-°F (~<NUM>/m-°C). The coefficient of thermal expansion may be measured at <NUM>°F (<NUM>).

The bearing <NUM> is disposed within an aperture <NUM> (e.g., a bore) of the mount <NUM> and its base <NUM>. The bearing <NUM> of <FIG>, for example, axially and/or circumferentially overlaps (e.g., covers, coats, etc.) and is attached (e.g., bonded, etc.) to an (e.g., cylindrical) inner surface of the mount <NUM> at the base inner side <NUM>. The bushing <NUM> is disposed within the stationary structure aperture <NUM>. The base <NUM> of <FIG>, for example, is received within (e.g., projects axially into) the stationary structure aperture <NUM>. The flange <NUM> is connected (e.g., fastened via one or more fasteners) to the stationary structure <NUM> to fix the bushing <NUM> and its mount <NUM> to the stationary structure <NUM>. The base <NUM> and its outer side <NUM> are abutted radially against the stationary structure <NUM> and its inner side <NUM>. The flange <NUM> and its second side <NUM> are abutted axially against the stationary structure <NUM> and its first side <NUM>. The mount <NUM> and its mount material may thereby radially and/or axially contact the stationary structure <NUM> and its stationary structure material. With this arrangement, the mount material provides a material bridge / buffer between the bearing material and the stationary structure material. The mount material, for example, is configured to accommodate / bridge the different material properties (e.g., coefficients of thermal expansion, bonding properties, etc.) of the bearing material and the stationary structure material.

In addition to providing a material property bridge, the mount material may be selected such that the bearing material may be bonded (e.g., applied) to the mount material without degrading material properties of the mount material. For example, the mount material may be a non-hardenable stainless steel (e.g., the above disclosed <NUM> or <NUM> series stainless steels) such that heat used during the bonding and/or application of the bearing material to the mount material will not degrade or undo previous hardening of the mount material. More particularly, the mount material may be selected such that the mount material does not need to be hardened via heat treatment prior to receiving the bearing material.

The bushing <NUM> extends circumferentially about (e.g., completely around) the rotating structure <NUM> and its shaft <NUM>; see also <FIG>. More particularly, the bearing <NUM> circumscribes the rotating structure <NUM> and its shaft <NUM>. An (e.g., cylindrical) inner surface of the bearing <NUM> at the bushing inner side <NUM> faces, radially abuts and radially engages (e.g., through an oil film and/or contacts) an (e.g., cylindrical) outer surface of the shaft <NUM> at the rotating structural outer side <NUM>. The bushing <NUM> and its bearing <NUM> may thereby rotatably support the rotating structure <NUM> and its shaft <NUM> within / relative to the stationary structure <NUM>.

In some embodiments, referring to <FIG>, the bushing <NUM> may include one or more intermediate elements between the mount <NUM> and the bearing <NUM>. The bushing <NUM> of <FIG>, for example, also includes an intermediate sleeve <NUM> radially between the base <NUM> and the bearing <NUM>. This sleeve <NUM> extends radially between and to a radial inner side <NUM> of the sleeve <NUM> and a radial outer side <NUM> of the sleeve <NUM>. The sleeve outer side <NUM> may radially abut against the mount inner side <NUM>. The sleeve inner side <NUM> may radially abut against the bearing outer side <NUM>. Thus, material forming the sleeve <NUM> may radially contact the mount material and/or the bearing material.

The sleeve material is selected to provide an additional material property bridge between the bearing material and the mount material. The sleeve material, for example, may be a low thermal expansion metal such as, but not limited to, plain carbon steel. The sleeve material is selected to have a coefficient of thermal expansion between <NUM>µin/in-°F (~<NUM>/m-°C) and <NUM>µin/in-°F (~<NUM>/m-°C). Inclusion of such a sleeve may be particularly useful where, for example, the mount material is a hardened stainless steel such as, but not limited to, hardened <NUM> stainless steel. The bearing material, for example, may be bonded and/or otherwise applied to the sleeve material. This coated sleeve may then be mounted (e.g., press fit or otherwise attached) to the mount <NUM> and its base <NUM> without, for example, affecting a hardness of the mount material.

<FIG> illustrates an example of the gas turbine engine with which the engine assembly <NUM> may be configured. This gas turbine engine is configured as a turboprop gas turbine engine <NUM>. This gas turbine engine <NUM> of <FIG> extends axially along a rotational axis <NUM> of the gas turbine engine <NUM> between a forward end <NUM> of the gas turbine engine <NUM> and an aft end <NUM> of the gas turbine engine <NUM>; which rotational axis <NUM> may be the same or different than the axial centerline <NUM>; see <FIG>. The gas turbine engine <NUM> of <FIG> includes an airflow inlet <NUM>, a combustion product exhaust <NUM>, a propulsor (e.g., a propeller) section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>.

The airflow inlet <NUM> is towards the engine aft end <NUM>, and aft of the turbine engine sections <NUM>-<NUM>. The exhaust <NUM> is located towards the engine forward end <NUM>, and axially between propulsor section <NUM> and the turbine engine sections <NUM>-<NUM>.

The propulsor section <NUM> includes a propulsor rotor <NUM>; e.g., a propeller. The compressor section <NUM> includes a compressor rotor <NUM>. The turbine section <NUM> includes a high pressure turbine (HPT) rotor <NUM> and a low pressure turbine (LPT) rotor <NUM>, where the LPT rotor <NUM> may be referred to as a power turbine rotor and/or a free turbine rotor. Each of these turbine engine rotors <NUM>, <NUM>, <NUM> and <NUM> includes a plurality of rotor blades arranged circumferentially about and connected to one or more respective rotor disks or hubs.

The propulsor rotor <NUM> of <FIG> is connected to the LPT rotor <NUM> sequentially through a propulsor shaft <NUM>, an epicyclic geartrain <NUM> (e.g., the geartrain <NUM>) and a low speed shaft <NUM>. The compressor rotor <NUM> is connected to the HPT rotor <NUM> through a high speed shaft <NUM>.

During gas turbine engine operation, air enters the gas turbine engine <NUM> through the airflow inlet <NUM>. This air is directed into a core flowpath which extends sequentially through the engine sections <NUM>-<NUM> (e.g., an engine core) to the exhaust <NUM>. The air within this core flowpath may be referred to as "core air".

The core air is compressed by the compressor rotor <NUM> and directed into a combustion chamber of a combustor <NUM> in the combustor section <NUM>. Fuel is injected into the combustion chamber and mixed with the compressed core air to provide a fuel-air mixture. This fuel-air mixture is ignited and combustion products thereof flow through and sequentially cause the HPT rotor <NUM> and the LPT rotor <NUM> to rotate. The rotation of the HPT rotor <NUM> drives rotation of the compressor rotor <NUM> and, thus, compression of air received from the airflow inlet <NUM>. The rotation of the LPT rotor <NUM> drives rotation of the propulsor rotor <NUM>, which propels air outside of the gas turbine engine <NUM> in an aft direction to provide forward thrust. The present disclosure, however, is not limited to any particular types or configurations of gas turbine engines as stated above.

Claim 1:
An assembly (<NUM>) for a gas turbine engine (<NUM>), comprising:
a rotating structure (<NUM>) extending axially along and rotatable about a centerline (<NUM>);
a stationary structure (<NUM>) extending circumferentially about the rotating structure (<NUM>), the stationary structure (<NUM>) comprising stationary structure material; and
a bushing (<NUM>) radially between the rotating structure (<NUM>) and the stationary structure (<NUM>), the bushing (<NUM>) including a mount (<NUM>) and a bearing (<NUM>) within the mount (<NUM>), the mount (<NUM>) comprising mount material, the mount material contacting the stationary structure material, the bearing (<NUM>) comprising bearing material engaged with and rotatably supporting the rotating structure (<NUM>), and the bearing material comprising copper,
characterised in that:
the stationary structure material has a coefficient of thermal expansion, measured at <NUM>, between <NUM>/m-°C and <NUM>/m-°C;
the mount material has a coefficient of thermal expansion, measured at <NUM>, between <NUM>/m-°C and <NUM>/m-°C; and
the mount material comprises stainless steel.