Patent Description:
Various seal assemblies are known in the art for gas turbine engine applications. While these known seal assemblies have various advantages, there is still a need in the art for improved seal assemblies as well as new applications to use seal assemblies in gas turbine engines. <CIT> and <CIT> disclose seal assemblies. <CIT> disclose a liftoff seal used on main shafts of gas turbines. <CIT> and <CIT> disclose tower shaft arrangements.

According to the invention there are provided assemblies for turbine engines as defined by the independent claims <NUM> and <NUM>.

<FIG> is a side cutaway illustration of a geared turbine engine <NUM>, which is configured as a turbofan engine for an aircraft propulsion system. This turbine engine <NUM> extends along an axial centerline <NUM> between an upstream airflow inlet <NUM> and a downstream airflow exhaust <NUM>.

The turbine engine <NUM> includes a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. The compressor section <NUM> includes a low pressure compressor (LPC) section 19A and a high pressure compressor (HPC) section 19B. The turbine section <NUM> includes a high pressure turbine (HPT) section 21A and a low pressure turbine (LPT) section 21B.

The engine sections <NUM>-<NUM> are arranged sequentially along the centerline <NUM> within an engine housing <NUM>. This housing <NUM> includes an inner case <NUM> (e.g., a core case) and an outer case <NUM> (e.g., a fan case). The inner case <NUM> may house one or more of the engine sections <NUM>-<NUM>; e.g., an engine core. The outer case <NUM> may house at least the fan section <NUM>.

Each of the engine sections <NUM>, 19A, 19B, 21A and 21B includes a respective bladed rotor <NUM>-<NUM>. Each of these bladed rotors <NUM>-<NUM> includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s).

The fan rotor <NUM> is connected to a gear train <NUM>, for example, through a fan shaft <NUM>. The gear train <NUM> and the LPC rotor <NUM> are connected to and driven by the LPT rotor <NUM> through a low speed shaft <NUM>. The combination of at least the LPC rotor <NUM>, the LPT rotor <NUM> and low speed shaft <NUM> may be referred to as a "low speed spool" or a "low speed rotating assembly". The HPC rotor <NUM> is connected to and driven by the HPT rotor <NUM> through a high speed shaft <NUM>. The combination of at least the HPC rotor <NUM>, the HPT rotor <NUM> and high speed shaft <NUM> may be referred to as a "high speed spool" or a "high speed rotating assembly". The shafts <NUM>-<NUM> are rotatably supported by a plurality of bearings <NUM>; e.g., rolling element and/or thrust bearings. Each of these bearings <NUM> is connected to the engine housing <NUM> by at least one stationary structure such as, for example, an annular support strut.

During operation, air enters the turbine engine <NUM> through the airflow inlet <NUM>. This air is directed through the fan section <NUM> and into a core gas path <NUM> and a bypass gas path <NUM>. The core gas path <NUM> flows sequentially through the engine sections <NUM>-<NUM>. The air within the core gas path <NUM> may be referred to as "core air". The bypass gas path <NUM> flows through a duct between the inner case <NUM> and the outer case <NUM>. The air within the bypass gas path <NUM> may be referred to as "bypass air".

The core air is compressed by the compressor rotors <NUM> and <NUM> and directed into a combustion chamber <NUM> of a combustor <NUM> in the combustor section <NUM>. This fuel air mixture is ignited and combustion products thereof expand and flow through and sequentially cause the turbine rotors <NUM> and <NUM> to rotate. The rotation of the turbine rotors <NUM> and <NUM> respectively drive rotation of the compressor rotors <NUM> and <NUM> and, thus, compression of the air received from an inlet to the core gas path <NUM>. The rotation of the turbine rotor <NUM> also drives rotation of the fan rotor <NUM> through the gear train <NUM>, which propels bypass air through and out of the bypass gas path <NUM>. The turbine engine <NUM> of the present disclosure, however, is not limited to the foregoing exemplary thrust ratio or specific engine configuration.

The turbine engine <NUM> of <FIG> also includes an accessory gearbox <NUM>, one or more gearbox attachments <NUM> and a transmission system <NUM>. The accessory gearbox <NUM> is mounted to the inner case <NUM>. However, in alternative embodiments, the accessory gearbox <NUM> may be mounted elsewhere with the turbine engine <NUM>; e.g., to the outer case <NUM>. The accessory gearbox <NUM> is configured to transfer rotational energy (e.g., torque) between the transmission system <NUM> and the one or more gearbox attachments <NUM>. An example of an accessory gearbox is disclosed in <CIT>.

Examples of a gearbox attachment may include an air turbine starter, a deoiler, a hydraulic pump, an oil pump, an integrated drive generator, a permanent magnet alternator and a fuel pump module. Of course, the present disclosure is not limited to including the foregoing exemplary types or configurations of the accessory gearbox <NUM> or the gearbox attachments <NUM>.

The transmission system <NUM> is configured to mechanically couple and thereby transfer rotational energy (e.g., torque) between a rotating assembly (or component) of the turbine engine <NUM> and the accessory gearbox <NUM>. In particular, the transmission system <NUM> of <FIG> mechanically couples one of the spools of the turbine engine <NUM> (e.g., the high speed spool) with the accessory gearbox <NUM>. This transmission system <NUM> includes the high speed shaft <NUM>, a tower shaft <NUM> and a coupling assembly such as a geared system <NUM>. Referring to <FIG>, the geared system <NUM> includes a first gear <NUM> and a second gear <NUM>.

The first gear <NUM> of <FIG> is configured as a bull gear such as, for example, a bevel bull gear. This first gear <NUM> is mounted to the high speed shaft <NUM>, for example, by a spline interface / connection <NUM> (e.g., see <FIG>). The first gear <NUM> has a first rotational axis <NUM>, which is coaxial with a rotational axis <NUM> of the low speed shaft <NUM>; e.g., the centerline <NUM>. The first gear <NUM> includes a plurality of first gear teeth <NUM>. These first gear teeth <NUM> are arranged in a circumferential array, which extends circumferentially around the first rotational axis <NUM>.

The second gear <NUM> of <FIG> is configured as a pinion gear such as, for example, a bevel pinion gear. This second gear <NUM> is mounted to the tower shaft <NUM>, for example, by a spline interface. The second gear <NUM> has a second rotational axis <NUM>, which is coaxial with a rotational axis <NUM> of the tower shaft <NUM>. This second rotational axis <NUM> is arranged coincident with and is angularly offset from (e.g., perpendicular to) the first rotational axis <NUM> as well as the centerline <NUM>. Of course, in other embodiments, the second rotational axis <NUM> may be arranged coincident with and acutely or obtusely angled to the first rotational axis <NUM>. The second gear <NUM> includes a plurality of second gear teeth <NUM>. These second gear teeth <NUM> are arranged in a circumferential array, which extends circumferentially around the second rotational axis <NUM>.

The second gear <NUM> is meshed (e.g., mated and engaged) with the first gear <NUM>. In particular, a subset of the first gear teeth <NUM> are mesh with a first subset of the second gear teeth <NUM>.

The tower shaft <NUM> and the second gear <NUM> are supported by a bearing <NUM> (e.g., a roller (ball) bearing), which bearing <NUM> rotatably connects the components <NUM> and <NUM> to a stationary structure <NUM> (e.g., an internal structure of / for the housing <NUM>) that circumscribes the components <NUM> and <NUM>. In particular, referring to <FIG>, a tubular base <NUM> of the second gear <NUM> projects axially along the rotational axis <NUM> through a bore of an inner race <NUM> (e.g., a split inner race) of the bearing <NUM>. An outer surface of the tubular base <NUM> radially engages (e.g., contacts) an inner surface of the inner race <NUM>. The bearing <NUM> of <FIG> is axially aligned with the spline connection <NUM> between the second gear <NUM> and the tower shaft <NUM>.

The bearing <NUM> as well as the gear system <NUM> and other engine components are housed within a compartment <NUM>; e.g., a bearing compartment. Fluid (e.g., gas) within this compartment <NUM> may be at a relatively high pressure. Components subject to such a relatively high fluid pressure may require use of more robust materials and/or designs. Therefore, to isolate the relatively high pressure fluid within the compartment <NUM> from areas and components (e.g., low pressure seals for the gearbox <NUM>) outside of the compartment <NUM>, the turbine engine <NUM> is configured with a fluid (e.g., gas) seal assembly <NUM>.

The seal assembly <NUM> of <FIG> is configured to at least partially or completely seal an annular gap between a stationary structure <NUM> (e.g., an internal structure of / for the housing <NUM>) and the second gear <NUM>, which stationary structure <NUM> circumscribes the tower shaft <NUM>. This seal assembly <NUM> includes a stationary (e.g., non-rotating) seal support assembly <NUM> and a stationary (e.g., non-rotating) seal element <NUM> such as, but not limited to, an annular carbon seal element. This seal element <NUM> extends circumferentially around the rotational axis <NUM>, <NUM> and is arranged to circumscribe the tower shaft <NUM>. Thus, the tower shaft <NUM> projects axially along the rotational axis <NUM> through a bore of the seal element <NUM>.

The seal support assembly <NUM> mounts the seal element <NUM> to the stationary structure <NUM>. The seal support assembly <NUM> is configured to bias (e.g., push) the seal element <NUM> axially towards the second gear <NUM> such that the seal element <NUM> axially engages (e.g., contacts) the second gear <NUM>. More particularly, the tubular base <NUM> of the second gear <NUM> extends axially along the rotational axis <NUM> to a distal annular end surface <NUM>. A distal annular end surface <NUM> of the seal element <NUM>, which is axially opposite and parallel with the end surface <NUM>, is biased axially against the end surface <NUM> to form a sealed interface between the seal element <NUM> and the second gear <NUM>.

Rubbing friction between the end surfaces <NUM> and <NUM> may cause the second gear <NUM> to heat up during rotation of the second gear <NUM> relative to the seal element <NUM>. The second gear <NUM> of <FIG> therefore is configured with one or more apertures <NUM>; e.g., lubricant passages and/or slots. These apertures <NUM> are arranged in a circumferential array about the rotational axis <NUM>, where each of the apertures <NUM> extends through a sidewall of the tubular base <NUM> of the second gear <NUM>. Thus, referring to <FIG>, each of the apertures <NUM> is adapted to direct lubricant <NUM> flowing within an intra-component passage <NUM> into the compartment <NUM>, where the lubricant <NUM> absorbs heat energy from the second gear <NUM> through conduction while passing through the apertures <NUM>.

The intra-component passage <NUM> of <FIG> extends axially through the spline connection <NUM> between the second gear <NUM> and the tower shaft <NUM> and into a first annulus <NUM> (e.g., an annular channel or cavity or an array of slots), which is axially between the spline connection <NUM> and a fluid permeable seal assembly <NUM>. The intra-component passage <NUM> then extends axially across the fluid permeable seal assembly <NUM> and into a second annulus <NUM> (e.g., an annular channel or cavity or an array of slots), which is axially between the fluid permeable seal assembly <NUM> and a fluid impermeable seal assembly <NUM>. This second annulus <NUM> is fluidly coupled with and, thus, is adapted to feed lubricant <NUM> into one or more of the apertures <NUM>.

The term "fluid permeable" may be used to describe a seal assembly configured to allow controlled fluid leakage thereacross. For example, referring to <FIG>, the fluid permeable seal assembly <NUM> may include a seal ring <NUM> (e.g., an annular spiral retaining ring) seated in a groove <NUM> of the tower shaft <NUM>. This groove <NUM> extends axially between a pair of circumferentially interrupted (e.g., splined or castellated) flanges <NUM>, which flanges <NUM> project radially out from a tubular sidewall of the tower shaft <NUM>. With such a configuration, a controlled rate of lubricant <NUM> may flow through the interruptions <NUM> (e.g., slots) in the flanges <NUM> and, thus, flow axially across the seal assembly <NUM>.

The term "fluid impermeable" may be used to describe a seal assembly configured to substantially or completely prevent fluid leakage thereacross. For example, referring to <FIG>, the fluid impermeable seal assembly <NUM> may include a seal ring <NUM> (e.g., an annular spiral retaining ring) seated in another groove <NUM> of the tower shaft <NUM>. This groove <NUM> extends axially between a pair of circumferentially uninterrupted flanges <NUM>, which flanges <NUM> project radially out from the tubular sidewall of the tower shaft <NUM>. With such a configuration, the combination of the elements <NUM> and <NUM> may substantially (compared to the controlled leakage across the seal assembly) prevent or completely prevent lubricant <NUM> flow across the seal assembly <NUM>.

Referring to <FIG>, in some embodiments, the turbine engine <NUM> may include a replaceable engine component that provides an intermediate body between the seal element <NUM> and the second gear <NUM>. In the specific embodiment of <FIG>, the replaceable engine component is configured as a seal runner <NUM>.

The seal runner <NUM> of <FIG> includes a tubular base <NUM> and an annular flange <NUM>, which are formed together as a unitary monolithic full hoop body. The tubular base <NUM> extends axially along the rotational axis <NUM>, <NUM> between axially opposed ends <NUM> and <NUM> of the seal runner <NUM>. The tubular base <NUM> includes a threaded portion <NUM> and a circumferentially interrupted (e.g., castellated) ring portion <NUM>. A first annulus <NUM> (e.g., an annular channel) is formed axially between the threaded portion <NUM> and the ring portion <NUM>. This annulus <NUM> is fluidly coupled with one or more apertures <NUM> (e.g., lubricant passages), which extend through a tubular sidewall of the tubular base <NUM>. These apertures <NUM> are arranged in a circumferential array about the rotational axis <NUM>, <NUM>. A second annulus <NUM> (e.g., an annular channel) is formed axially between the annular flange <NUM> and the ring portion <NUM>.

The annular flange <NUM> is located at (e.g., on, adjacent or proximate) the second end <NUM> of the seal runner <NUM>. The annular flange <NUM> extends circumferentially about the rotational axis <NUM>, <NUM>. The annular flange <NUM> projects radially out from the tubular base <NUM> to a distal end <NUM>. The annular flange <NUM> of <FIG> includes a circumferentially uninterrupted inner portion <NUM> and a circumferentially interrupted outer portion <NUM> (e.g., a castellated, slotted outer peripheral portion). The inner portion <NUM> extends radially from the tubular base <NUM> to the outer portion <NUM>. The outer portion <NUM> extends radially from the inner portion <NUM> to the distal end <NUM>. The outer portion <NUM> is configured with one or more slots <NUM>. Each of these slots <NUM> extends radially into the annular flange <NUM> from the distal end <NUM>. Each of the slots <NUM> extends axially through the annular flange <NUM>. This arrangement of slots <NUM> may be configured for mating with a tool to aid in the installation and/or removal of the seal runner <NUM> from the turbine engine <NUM>.

Referring to <FIG>, the seal runner <NUM> is disposed in a cavity radially between the second gear <NUM> and the tower shaft <NUM>. The seal runner <NUM> is mounted to the second gear <NUM> by a threaded connection <NUM> between the tubular bases <NUM> and <NUM>. More particularly, the threaded portion <NUM> of the seal runner <NUM> is mated with (thread into) a threaded portion <NUM> of the second gear <NUM>. The annular flange <NUM> may be axially abutted against the distal end surface <NUM> of the second gear <NUM>, which in the embodiment of <FIG> is circumferentially interrupted.

With the installation of the seal runner <NUM>, the seal element <NUM> is configured to axially engage (e.g., contact) a distal annular end surface <NUM> of the seal runner <NUM> and its inner portion <NUM> and annular flange <NUM> in a similar manner as described above with respect to the engagement between the components <NUM> and <NUM> (see <FIG>).

Rubbing friction between the end surfaces <NUM> and <NUM> may cause the seal runner <NUM> to heat up during rotation of the seal runner <NUM> relative to the seal element <NUM>. The seal runner <NUM> of <FIG> therefore is configured with the one or more apertures <NUM>. Referring to <FIG>, the apertures <NUM> are operable to direct lubricant <NUM> flowing within the intra-component passage <NUM> into the compartment <NUM>, where the lubricant <NUM> absorbs heat energy from the seal runner <NUM> through conduction while passing through the apertures <NUM> and along the axially and radially extending surfaces <NUM> and <NUM> of the seal runner <NUM>.

The intra-component passage <NUM> of <FIG> extends axially through the spline connection <NUM> between the second gear <NUM> and the tower shaft <NUM> and into the first annulus <NUM>. The intra-component passage <NUM> then extends axially across the fluid permeable seal assembly <NUM> and into the second annulus <NUM>. This second annulus <NUM> is fluidly coupled with and, thus, is adapted to feed lubricant <NUM> into one or more of the apertures <NUM>. The lubricant <NUM> then passes sequentially through the first annulus <NUM> and slots in the ring portion <NUM> and into the second annulus <NUM>. To enable the lubricant <NUM> to flow out of the second annulus <NUM> and into the compartment <NUM>, the distal end surface <NUM> of the second gear <NUM> in the embodiment of <FIG> (not in the embodiment of <FIG>) may be circumferentially interrupted by one or more slots; e.g., a distal end of the second gear <NUM> may be castellated.

In the embodiment of <FIG>, the seal rings <NUM> and <NUM> of the seal assemblies <NUM> and <NUM> are configured to radially engage (e.g., contact) an inner surface <NUM> of the seal runner <NUM> rather than an inner surface of the second gear <NUM> as shown in <FIG>. In some embodiments, the inner surface <NUM> of the seal runner <NUM> may be recessed radially outward from an inner lip <NUM> of the seal runner <NUM>. With such a configuration, the lip <NUM> may function as a retainer for the tower shaft <NUM> during installation.

Claim 1:
An assembly for a turbine engine, comprising:
a tower shaft (<NUM>) rotatable about an axis (<NUM>, <NUM>);
a pinion gear (<NUM>) mounted to the tower shaft (<NUM>), a tubular base (<NUM>) of the pinion gear (<NUM>) extending axially along the axis (<NUM>, <NUM>) to a distal annular end surface (<NUM>);
a stationary structure (<NUM>) circumscribing the tower shaft (<NUM>); and
a seal assembly (<NUM>) sealing a gap between the stationary structure (<NUM>) and the pinion gear (<NUM>); characterised by:
the seal assembly (<NUM>) comprising an annular seal element (<NUM>) circumscribing the tower shaft (<NUM>) and axially contacting the distal annular end surface (<NUM>).