Patent Description:
Gas turbine engines include compressor sections to compress an airflow, combustor sections that combine the airflow with fuel for combustion and generate exhaust, and turbine sections that convert the exhaust into torque to drive the compressor sections. Gas turbine engines may include static to rotating interfaces, such as near bearing compartments, around shafts, or the like. It may be desirable to occasionally provide sealing at these interfaces. Such sealing may be relatively difficult due to heat generated by friction between the static component and the rotating component. Furthermore, it is desirable to reduce oil leakage at such seal locations.

<CIT> discloses, for a rotating carbon seal that requires lubrication, a rotating self-actuating weepage valve responding to speed and/or pressure for closure of the valve at a given operating condition.

Disclosed is a wet-dry face seal seat configured to rotate about an axis. The wet-dry face seal seat includes a main body having a mating face configured to mate with a sealing member, an outer diameter surface, and an axial face, the main body defining a pool feed passage that extends to the mating face and a cooling hole that extends to the outer diameter surface. The main body defines an oil pool on the mating face in fluid communication with the pool feed passage. The wet-dry face seal seat further includes an oil capture scoop having an axial portion extending away from the main body, and a radial portion extending radially inward from the axial portion, the axial portion of the oil capture scoop, the radial portion of the oil capture scoop, and the axial face of the main body defining an oil volume, the axial face of the main body further defining a pool feed inlet in fluid communication with the pool feed passage, and the axial portion of the oil capture scoop defining a cooling inlet in fluid communication with the cooling hole.

In any of the foregoing embodiments, a distance between the axial portion of the oil capture scoop and the pool feed inlet along with the cooling inlet being located on the axial portion allows oil to flow through the cooling hole in response to oil flow from an oil jet being below a threshold value and through the pool feed passage in response to the oil flow from the oil jet reaching or exceeding the threshold value.

In any of the foregoing embodiments, the pool feed passage includes a pool feed hole extending from the oil volume to the oil pool, and a pool discharge hole extending from the oil pool to the outer diameter surface.

In any of the foregoing embodiments, the wet-dry face seal seat is configured for use in a gas turbine engine.

In any of the foregoing embodiments, the main body and the oil capture scoop include at least one of a metallic material, a non-metallic material, or a hybrid metallic and non-metallic material.

Also disclosed is a wet-dry face seal. The wet-dry face seal includes a sealing member. The wet-dry face seal further includes a wet-dry face seal seat configured to rotate relative to the sealing member. The wet-dry face seal seat includes a main body having a mating face configured to mate with the sealing member, an outer diameter surface, and an axial face, the main body defining a pool feed passage that extends to the mating face and a cooling hole that extends to the outer diameter surface. The main body defines an oil pool on the mating face in fluid communication with the pool feed passage. The wet-dry face seal seat further includes an oil capture scoop having an axial portion extending away from the main body, and a radial portion extending radially inward from the axial portion, the axial portion of the oil capture scoop, the radial portion of the oil capture scoop, and the axial face of the main body defining an oil volume, the axial face of the main body further defining a pool feed inlet in fluid communication with the pool feed passage, and the axial portion of the oil capture scoop defining a cooling inlet in fluid communication with the cooling hole.

The foregoing features and elements are to be combined in various combinations without exclusivity, unless expressly indicated otherwise.

A more complete understanding of the present disclosure, however, is best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration and their best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the inventions, it should be understood that other embodiments may be realized and that logical, chemical and mechanical changes may be made without departing from the scope of the inventions. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Where used herein, the phrase "at least one of A or B" can include any of "A" only, "B" only, or "A and B.

With reference to <FIG>, a gas turbine engine <NUM> is provided. As used herein, "aft" refers to the direction associated with the tail (e.g., the back end) of an aircraft, or generally, to the direction of exhaust of the gas turbine engine. As used herein, "forward" refers to the direction associated with the nose (e.g., the front end) of an aircraft, or generally, to the direction of flight or motion. As utilized herein, radially inward refers to the negative R direction and radially outward refers to the R direction. An A-R-C axis is shown throughout the drawings to illustrate the relative position of various components.

The gas turbine engine <NUM> may be a two-spool turbofan that generally incorporates a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. In operation, the fan section <NUM> drives air along a bypass flow-path B while the compressor section <NUM> drives air along a core flow-path C for compression and communication into the combustor section <NUM> then expansion through the turbine section <NUM>. Although depicted as a turbofan gas turbine engine <NUM> herein, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines.

The gas turbine engine <NUM> generally comprises a low speed spool <NUM> and a high speed spool <NUM> mounted for rotation about an engine central longitudinal axis X-X' relative to an engine static structure <NUM> via several bearing systems <NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. It should be understood that various bearing systems <NUM> at various locations may alternatively or additionally be provided, including for example, the bearing system <NUM>, the bearing system <NUM>-<NUM>, and the bearing system <NUM>-<NUM>.

The low speed spool <NUM> generally includes an inner shaft <NUM> that interconnects a fan <NUM>, a low pressure (or first) compressor section <NUM> and a low pressure (or second) turbine section <NUM>. The inner shaft <NUM> is connected to the fan <NUM> through a geared architecture <NUM> that can drive the fan shaft <NUM>, and thus the fan <NUM>, at a lower speed than the low speed spool <NUM>. The geared architecture <NUM> includes a gear assembly <NUM> enclosed within a gear housing <NUM>. The gear assembly <NUM> couples the inner shaft <NUM> to a rotating fan structure.

The high speed spool <NUM> includes an outer shaft <NUM> that interconnects a high pressure (or second) compressor section <NUM> and the high pressure (or first) turbine section <NUM>. A combustor <NUM> is located between the high pressure compressor <NUM> and the high pressure turbine <NUM>. A mid-turbine frame <NUM> of the engine static structure <NUM> is located generally between the high pressure turbine <NUM> and the low pressure turbine <NUM>. The mid-turbine frame <NUM> supports one or more bearing systems <NUM> in the turbine section <NUM>. The inner shaft <NUM> and the outer shaft <NUM> are concentric and rotate via the bearing systems <NUM> about the engine central longitudinal axis X-X', which is collinear with their longitudinal axes. As used herein, a "high pressure" compressor or turbine experiences a higher pressure than a corresponding "low pressure" compressor or turbine.

The core airflow C is compressed by the low pressure compressor section <NUM> then the high pressure compressor <NUM>, mixed and burned with fuel in the combustor <NUM>, then expanded over the high pressure turbine <NUM> and the low pressure turbine <NUM>. The mid-turbine frame <NUM> includes airfoils <NUM> which are in the core airflow path.

The gas turbine engine <NUM> is a high-bypass ratio geared aircraft engine. The bypass ratio of the gas turbine engine <NUM> may be greater than about six (<NUM>). The bypass ratio of the gas turbine engine <NUM> may also be greater than ten (<NUM>:<NUM>). The geared architecture <NUM> may be an epicyclic gear train, such as a star gear system (sun gear in meshing engagement with a plurality of star gears supported by a carrier and in meshing engagement with a ring gear) or other gear system. The geared architecture <NUM> may have a gear reduction ratio of greater than about <NUM> and the low pressure turbine <NUM> may have a pressure ratio that is greater than about five (<NUM>). The diameter of the fan <NUM> may be significantly larger than that of the low pressure compressor section <NUM>, and the low pressure turbine <NUM> may have a pressure ratio that is greater than about five (<NUM>:<NUM>). The pressure ratio of the low pressure turbine <NUM> is measured prior to an inlet of the low pressure turbine <NUM> as related to the pressure at the outlet of the low pressure turbine <NUM>. It should be understood, however, that the above parameters are exemplary of various embodiments of a suitable geared architecture engine and that the present disclosure contemplates other turbine engines including direct drive turbofans.

The next generation turbofan engines are designed for higher efficiency and use higher pressure ratios and higher temperatures in the high pressure compressor <NUM> than are conventionally experienced. These higher operating temperatures and pressure ratios create operating environments that cause thermal loads that are higher than the thermal loads conventionally experienced, which may shorten the operational life of current components.

Referring now to <FIG>, a wet-dry face seal <NUM> may be used to seal a bearing, bearing compartment, or shaft in one or more bearing system <NUM> or other location of the gas turbine engine <NUM> of <FIG>. The wet-dry face seal <NUM> may include a sealing member <NUM> and a wet-dry face seal seat <NUM>. The wet-dry face seal seat <NUM> may rotate about an axis <NUM>, and the sealing member <NUM> may remain stationary relative to the axis <NUM>. In that regard, the wet-dry face seal <NUM> may be used to seal any rotating to static interfaces. The sealing member <NUM> may be loaded against the wet-dry face seal seat <NUM> such as, for example, via a spring, via air pressure, or the like.

In various embodiments, the sealing member <NUM> may include a carbon material, a carbon composite material, a plastic material (e.g., a thermoplastic or a thermoset), polytetrafluoroethylene (PTFE), or other material that provides a relatively low friction coefficient. In various embodiments, the wet-dry face seal seat <NUM> may include metallic materials such as steel, non-metallic materials such as ceramics or plastics, or metallic/non-metallic hybrid composite materials such as chromium carbide, or the like. In various embodiments, the sealing member <NUM> and the wet-dry face seal seat <NUM> may include any suitable materials.

The wet-dry face seal seat <NUM> includes a main body <NUM> and an oil capture scoop <NUM>. The oil capture scoop <NUM> may include an axial portion <NUM> extending axially away from the main body <NUM> and a radial portion <NUM> extending radially inward from the axial portion <NUM>.

The main body <NUM> may have an inner diameter surface <NUM>, an outer diameter surface <NUM>, a mating face <NUM>, and an axial face <NUM>. The mating face <NUM> is designed to mate with the sealing member <NUM>. Stated differently, the mating face <NUM> is designed to contact the sealing member <NUM> to form a seal therebetween.

The inner diameter surface <NUM> may face radially inward, and the outer diameter surface <NUM> may face radially outward. In various embodiments, the inner diameter surface <NUM> may be oriented on an opposite side of the main body <NUM> from the outer diameter surface <NUM>. In various embodiments, the axial face <NUM> may face in an axial direction, and may be oriented or situated on an opposite side of the main body <NUM> from the mating face <NUM>.

The axial face <NUM> of the main body <NUM>, the axial portion <NUM> of the oil capture scoop <NUM>, and the radial portion <NUM> of the oil capture scoop <NUM> define an oil volume <NUM>. The oil volume <NUM> may receive oil from an oil jet <NUM>.

The main body <NUM> may include a pool feed passage <NUM> that extends from a pool feed inlet <NUM> on the axial face towards an oil pool <NUM> defined by the main body <NUM>. For example, the oil pool <NUM> may be defined on the mating face <NUM> and may include a cavity or volume in which oil may collect. In various embodiments, the pool feed passage <NUM> may include a pool feed hole <NUM> that extends from the axial face <NUM> to the oil pool <NUM>, and a pool discharge hole <NUM> that extends from the oil pool <NUM> to the outer diameter surface <NUM>. The oil from the oil pool <NUM> may cool the interface of the mating face <NUM> and the sealing member <NUM>, and may reduce friction on this interface. In that regard, the oil from the oil pool <NUM> may spread along the mating face <NUM>. In various embodiments, oil from the pool feed passage <NUM> may be directly ported to the mating face <NUM> without inclusion of an oil pool <NUM>. A portion of the oil from the oil pool <NUM> may be ported through the pool discharge hole <NUM> towards the outer diameter surface <NUM>.

The main body <NUM> may further include a cooling hole <NUM> that extends from a cooling inlet <NUM> towards the outer diameter surface <NUM>. In various embodiments, the cooling inlet <NUM> may be defined by the axial portion <NUM> of the oil capture scoop <NUM>. The cooling hole <NUM> may transfer or port oil or another fluid from the oil volume <NUM> through the wet-dry face seal seat <NUM> in order to cool the wet-dry face seal seat <NUM>. The oil may exit the wet-dry face seal seat <NUM> from the cooling hole <NUM> on the outer diameter surface <NUM>.

Heat may be generated at the interface between the sealing member <NUM> and the mating face <NUM>. In that regard, the oil in the cooling hole <NUM> may transfer heat away from the wet-dry face seal seat <NUM>.

Wet seals (that include pool feed passages) may provide superior durability relative to dry seals due to the decrease in friction at the interface. During engine operation, the air pressure in a first cavity <NUM>, exterior to the bearing compartment <NUM>, may be greater than air pressure in a second cavity <NUM>, which is internal relative to the bearing compartment <NUM>. However, conventional wet seals may undesirably leak oil between a mating face and a sealing member in response to relatively low differential air pressure across the seal <NUM>. For example, such leakage may occur during starting and idle conditions of a corresponding gas turbine engine when the air pressure in the first cavity <NUM> is relatively low. This is because oil leakage is typically controlled by air pressure differential across the seal <NUM> (i.e., from an inner diameter surface to an outer diameter surface) which tends to be relatively low during starting and idle conditions.

The wet-dry face seal <NUM> is designed to provide the benefits of a wet seal without the detriments of the wet seal. The orientation of the oil capture scoop <NUM> provides this benefit by allowing oil to flow through the cooling hole <NUM> and not the pool feed passage <NUM> in response to the oil flow from the oil jet <NUM> being below a threshold value, and allowing the oil to flow through the pool feed passage <NUM> in response to the oil flow from the oil jet <NUM> reaching or exceeding the threshold value. The oil flow from the oil jet <NUM> may increase as rotational velocity of the wet-dry face seal seat <NUM> increases. The threshold value of oil flow may correspond to an engine power setting, such as idle, above which oil leakage between the sealing member <NUM> and the mating face <NUM> is relatively unlikely or nonexistent. This functionality may be at least partially provided by a radial distance <NUM> of the oil capture scoop <NUM> or a distance <NUM> from the axial portion <NUM> of the oil capture scoop <NUM>. The radial distance <NUM> corresponds to a distance between the axial portion <NUM> and a radially inner end of the radial portion <NUM>.

The flow of oil from the oil jet <NUM> may vary in proportion to engine power levels or shaft speed. In response to any rotation of the wet-dry face seal seat <NUM>, oil from the oil jet <NUM> is received by an inner surface <NUM> of the axial portion <NUM>, thus allowing oil to flow through the cooling hole <NUM> via the cooling inlet <NUM> at any rotational velocity of the wet-dry face seal seat <NUM>. The pool feed inlet <NUM> is located a distance <NUM> from the axial portion <NUM> of the oil capture scoop <NUM> which reduces the likelihood of the pool feed inlet <NUM> receiving oil while the oil from the oil jet is below the threshold value. The distance <NUM> may be, for example, between <NUM> inches and <NUM> inches (<NUM> millimeters (mm) and <NUM>, between <NUM> inches and <NUM> inches (<NUM> and <NUM>), or between <NUM> inch and <NUM> inches (<NUM> and <NUM>). In various embodiments, oil flow through the cooling hole <NUM> is constant in response to the oil flow from the oil jet <NUM> reaching or exceeding the threshold value.

A cooling diameter <NUM> of the cooling hole <NUM> may be selected such that all oil from the oil jet <NUM> flows through the cooling hole <NUM> in response to the oil flow from jet <NUM> being below the threshold value. As the engine power level is increased, oil flow from the oil jet <NUM> reaches or exceeds the threshold value, pressure on the inner diameter causes the oil to pool within the oil volume <NUM> such that it reaches the pool feed inlet <NUM> and flows through the pool feed passage <NUM>. Stated differently, the flow of oil from jet <NUM> may exceed the flow capacity of the cooling hole <NUM>. In that regard, the cooling diameter <NUM> and the distance <NUM> are selected such that the oil may flow through the pool feed passage <NUM> in response to the oil flow from the oil jet <NUM> reaching or exceeding the threshold value.

The cooling diameter <NUM> may be, for example, between <NUM> inches and <NUM> inches (<NUM> and <NUM>), between <NUM> inches and <NUM> inches (<NUM> and <NUM>), or between <NUM> inches and <NUM> inches (<NUM> and <NUM>).

The pool feed passage <NUM> may have a feed diameter <NUM>. The feed diameter <NUM> may be, for example, between <NUM> inches and <NUM> inches (<NUM> millimeters (mm) and <NUM>), between <NUM> inches and <NUM> inches (<NUM> and <NUM>), or between <NUM> inches and <NUM> inches (<NUM> and <NUM>).

Turning now to <FIG>, an exemplary use of the wet-dry face seal <NUM> is shown. As shown, the wet-dry face seal <NUM> abuts against a shaft <NUM> and provides sealing capabilities for a bearing compartment <NUM>. In particular, the wet-dry face seal <NUM> seals the bearing compartment <NUM> from surrounding areas to allow oil to collect and remain within the bearing compartment <NUM>. The wet-dry face seal <NUM> also seals the bearing compartment <NUM> from surrounding areas to prevent or minimize air entry. Typically this air is pressurized, elevated in temperature and/or contaminated with environmental debris so its entry into the bearing compartment adversely impacts the performance and efficiency of the bearing compartment. The bearing compartment <NUM> may be defined between a first bearing compartment housing <NUM>, a second bearing compartment housing <NUM>, and the shaft <NUM>. A bearing <NUM> and a bearing support <NUM> may be spaced from the wet-dry face seal <NUM> by a spacer <NUM>. As shown, the wet-dry face seal <NUM> (and in particular the oil capture scoop <NUM>) receives oil from the oil j et <NUM> as shown by an arrow <NUM>.

In various embodiments and referring to <FIG>, a bearing <NUM> and a bearing support <NUM> may be located between an oil nozzle <NUM> and a wet-dry face seal <NUM>. In this arrangement, an oil capture scoop <NUM>, similar to the oil capture scoop <NUM> of <FIG>, may be incorporated into the bearing <NUM> or a spacer <NUM> or a similar part mounted on a shaft <NUM>. The captured oil may then be transmitted, such as through slots or passages <NUM> between inner diameters of the bearing <NUM> and spacer <NUM>, <NUM> and an outer diameter of the shaft <NUM>, to the wet-dry face seal <NUM>. In such an arrangement, a scoop <NUM> on the wet-dry face seal <NUM> may be located radially inward and radially aligned with the spacer <NUM>. Additionally, the radial portion of the scoop <NUM> may be modified to permit oil to flow through slots or passages in the inner diameter of the spacer <NUM> to enter the scoop <NUM>.

However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the inventions. The scope of the invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more.

In the detailed description herein, references to "one embodiment", "an embodiment", "various embodiments", etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the invention in alternative embodiments.

Claim 1:
A wet-dry face seal seat (<NUM>) configured to rotate about an axis, comprising:
a main body (<NUM>) having a mating face (<NUM>) configured to mate with a sealing member (<NUM>), an outer diameter surface (<NUM>), and an axial face (<NUM>),
characterised by the main body (<NUM>) defining a pool feed passage (<NUM>) that extends to the mating face (<NUM>) and a cooling hole (<NUM>) that extends to the outer diameter surface (<NUM>), wherein the main body (<NUM>) defines an oil pool (<NUM>) on the mating face (<NUM>) in fluid communication with the pool feed passage (<NUM>); and
an oil capture scoop (<NUM>) having an axial portion (<NUM>) extending away from the main body (<NUM>), and a radial portion (<NUM>) extending radially inward from the axial portion(<NUM>), the axial portion (<NUM>) of the oil capture scoop (<NUM>), the radial portion (<NUM>) of the oil capture scoop (<NUM>), and the axial face (<NUM>) of the main body (<NUM>) defining an oil volume (<NUM>), the axial face (<NUM>) of the main body (<NUM>) further defining a pool feed inlet (<NUM>) in fluid communication with the pool feed passage (<NUM>), and the axial portion (<NUM>) of the oil capture scoop (<NUM>) defining a cooling inlet (<NUM>) in fluid communication with the cooling hole (<NUM>).