Patent Description:
Modern aircraft may utilize one or more turbofan propulsion systems powered by a gas turbine engine. The propulsion systems may include a nacelle, which is a system of components that house the engine and its ancillary systems, and help form aerodynamic surfaces for flight, including a fan bypass air duct. Often, the nacelle includes a cowl or a pair of cowls. The cowl is typically hinged to a fix structure, such as, for example, a pylon, and facilitates access to the engine and the ancillary systems when opened. The cowl also defines an annular shaped compartment that surrounds an inner fixed structure and in which several ducts carrying high pressure fluids or gases reside. During various operating conditions, such as after a burst duct, pressure in the compartment may become abnormally high and, as a result, place a radially outward load against the cowl. The radially outward load against the cowl may result in a radial deflection of the cowl, particularly at a junction between the cowl and an air inlet structure of the nacelle just forward of the cowl. The resulting misalignment of the cowl and the air inlet structure may lead to a phenomena known as scooping, where the high speed ambient air outside the nacelle enters the compartment beneath the cowl, thereby pressurizing the internal surface of the cowl. Scooping may adversely affect the aerodynamic shape of the nacelle and, in some instances, result in damage to or even loss of the cowl from the nacelle. <CIT> and <CIT> disclose arrangements of the prior art.

According to an aspect of the invention, a cowl system for a nacelle of an aircraft is provided according to claim <NUM>.

Optionally, the first hinge stop is connected to a cowl flange.

Optionally, the second face is configured to abut the first face when the cowl is rotated toward the closed position. Optionally, the first face and the second face are configured to separate when the cowl is rotated toward an open position.

Optionally, the fixed structure is a pylon. Optionally, the first pin is connected to a pylon flange connected to and extending from the pylon. Optionally, the first pin is configured for coaxial disposition with a hinge line of the cowl.

The first hinge stop includes a first face and the second hinge stop includes a second face configured to abut the first face when the cowl is rotated toward a closed position. Optionally, the first face and the second face are configured to separate when the cowl is rotated toward an open position.

Optionally, the cowl system further includes a second hinge, a third hinge and a fourth hinge pivotally mounting the cowl to the fixed structure. Optionally, the second hinge includes a clevis and a lug.

The features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings.

While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that changes may be made within the scope of the appended claims.

Referring to <FIG>, a gas turbine engine <NUM> is illustrated according to various embodiments. The gas turbine engine <NUM> includes a nacelle <NUM> that surrounds a core engine structure. In various embodiments, the nacelle <NUM> includes an air inlet <NUM>, a cowl <NUM> and a thrust reverser <NUM>. The nacelle <NUM> may be coupled to a pylon <NUM>, which may mount the nacelle <NUM> and the core engine structure to an aircraft wing or aircraft body. The nacelle <NUM> may further include an exhaust nozzle assembly including a nozzle <NUM> and an aft cowl <NUM> surrounding a center body <NUM> having a generally conical shape and, in various embodiments, an associated attachment structure. A high-temperature exhaust stream from the core engine structure exits the gas turbine engine <NUM> between the nozzle <NUM> and the center body <NUM>.

Referring now to <FIG>, there is seen a schematic side view of a gas turbine engine <NUM> mounted on a pylon <NUM>, which may be secured to an underside of an aircraft wing or to a portion of a fuselage of the aircraft. A nacelle <NUM> surrounds a core engine structure and various related components of the gas turbine engine <NUM>. A cowl <NUM> (or a first cowl) is hingedly (e.g., mounted by a hinge) mounted to the pylon <NUM> in a manner permitting the cowl <NUM> to be rotated upward and away from the gas turbine engine <NUM>, thereby exposing the core engine structure and various related components to permit access for examination or repair. A second cowl (hidden) is hingedly mounted on the opposite side of the pylon <NUM>. Without loss of generality, in various embodiments, the cowl <NUM> pivots on four hinge assemblies located just within the cowl <NUM> and not seen in <FIG>. The cowl <NUM> typically pivots about a hinge line <NUM> defined by the locations of the four hinge assemblies, including a first hinge assembly <NUM>, a second hinge assembly <NUM>, a third hinge assembly <NUM> and a fourth hinge assembly <NUM>. A cowl lock <NUM> is positioned at a lower end <NUM> of the cowl <NUM> and configured to maintain the cowl <NUM> in the closed position during operation. One or more of the four hinge assemblies may comprise a conventional clevis and lug coupled together via a pin that extends coaxially with the hinge line <NUM>. At the same time, one or more of the four hinge assemblies, and particularly the first hinge assembly <NUM>, comprise a dual axis hinge <NUM>, which is defined, at least in part, by a first axis <NUM> that is coaxial with the hinge line <NUM> and a second axis <NUM> that is offset from the hinge line <NUM>. As described in more detail below, the dual axis hinge <NUM> is configured to limit radial displacement of a forward edge <NUM> of the cowl <NUM> in a radially outward direction with respect to an aft edge <NUM> of an air inlet <NUM> of the nacelle <NUM> when the cowl <NUM> assumes a closed position. Limiting radial displacement of the forward edge <NUM> of the cowl <NUM> from moving in a radially outward direction, or otherwise limiting or controlling the size of a radial gap caused by such movement, prevents the phenomena known as scooping, as above described.

Referring now to <FIG>, a dual axis hinge <NUM>, similar to the dual axis hinge <NUM> described above with reference to <FIG>, is illustrated connected to a cowl <NUM> in a closed position (see <FIG>) and in an open position (see <FIG>). In various embodiments, the dual axis hinge <NUM> includes a link <NUM> having a first end <NUM> pivotally secured to a fixed structure, such as, for example, a pylon <NUM> or a pylon flange <NUM> connected to and extending from the pylon <NUM>, and a second end <NUM> pivotally secured to the cowl <NUM>. A first pin <NUM> is used to secure the first end <NUM> of the link <NUM> to the fixed structure, with the first pin <NUM> extending axially along a first axis <NUM>. In various embodiments, the first axis <NUM> is coaxial with a hinge line <NUM> of the cowl <NUM>, similar to the hinge line <NUM> described above with reference to <FIG>. A second pin <NUM> is used to secure the second end <NUM> of the link <NUM> to a cowl flange <NUM> connected to and extending from an inside surface <NUM> of the cowl <NUM>, with the second pin <NUM> extending axially along a second axis <NUM>. In various embodiments, the second axis <NUM> is offset from the first axis <NUM>, as well as the hinge line <NUM> of the cowl <NUM>, similar to the arrangement described above with reference to <FIG>.

In various embodiments, a first hinge stop <NUM> is connected to the inside surface <NUM> of the cowl <NUM> via the cowl flange <NUM> and a second hinge stop <NUM> is connected to the link <NUM> proximate the second end <NUM> of the link <NUM>. The connection of the first hinge stop <NUM> to the cowl <NUM> is typically a rigid connection, such that the first hinge stop <NUM> is prevented from movement with respect to the cowl <NUM>. For example, in various embodiments, the first hinge stop <NUM> is welded or bolted to the cowl flange <NUM> or, in various embodiments, the first hinge stop <NUM> and the cowl flange <NUM> are constructed as a monolithic or single-piece unit. Similarly, the connection of the second hinge stop <NUM> to the link <NUM> is typically a rigid connection, such that the second hinge stop <NUM> is prevented from movement with respect to the link <NUM>. For example, in various embodiments, the second hinge stop <NUM> is welded or bolted to the second end <NUM> of the link <NUM> or, in various embodiments, the second hinge stop <NUM> and the link <NUM> are constructed as a monolithic or single-piece unit. The first hinge stop <NUM> includes a first face <NUM> and the second hinge stop <NUM> includes a second face <NUM> configured to abut the first face <NUM> when the cowl <NUM> assumes a closed position.

As illustrated in <FIG>, when the cowl <NUM> assumes the closed position, the first hinge stop <NUM> and the second hinge stop <NUM> contact one another. More specifically, in various embodiments, when the cowl <NUM> assumes the closed position, the first face <NUM> of the first hinge stop <NUM> and the second face <NUM> of the second hinge stop <NUM> abut one another. The manner of contact prevents an upper portion <NUM> of the cowl <NUM> from moving or otherwise being displaced in a radial direction R in response to a load or a force F acting in the radial direction R on the inside surface <NUM> of the cowl <NUM>. A cowl lock, such as, for example, the cowl lock <NUM> described above with reference to <FIG>, is secured at a lower end <NUM> of the cowl <NUM> in order to prevent the dual axis hinge <NUM> from rotating about the first axis <NUM> in response to the load or the force F acting in the radial direction R on the inside surface <NUM> of the cowl <NUM>. Referring now to <FIG>, once the cowl lock at the lower end <NUM> of the cowl <NUM> is released, the cowl <NUM> is able to rotate with respect to second end <NUM> of the link <NUM> in a direction that enables a space to be created between the first face <NUM> and the second face <NUM>. Further, the link <NUM> is able to rotate about the first axis <NUM>, which, as described above, is typically coaxial with the hinge line <NUM>. This enables the various hinges pivotally connecting the cowl <NUM> to the fixed structure (e.g., to the pylon <NUM> or to the pylon flange <NUM>) to rotate about the hinge line <NUM> such that the cowl may assume the open position.

Referring now to <FIG>, a cowl system <NUM> is illustrated. In various embodiments, the cowl system <NUM> includes a first cowl <NUM><NUM> and a second cowl <NUM><NUM> pivotally secured to a fixed structure, such as, for example, a pylon <NUM> or a pylon flange <NUM> connected to and extending from the pylon <NUM>. Focusing on the first cowl <NUM><NUM>, a first dual axis hinge <NUM><NUM> includes a link <NUM> having a first end <NUM> pivotally secured to the fixed structure and a second end <NUM> pivotally secured to the first cowl <NUM><NUM>. A first pin <NUM> is used to secure the first end <NUM> of the link <NUM> to the fixed structure, with the first pin <NUM> extending axially along a first axis <NUM>, the first axis <NUM> being coaxial with a first hinge line <NUM><NUM> of the first cowl <NUM><NUM>, similar to the hinge line <NUM> described above with reference to <FIG>. A second pin <NUM> is used to secure the second end <NUM> of the link <NUM> to a cowl flange <NUM> connected to and extending from an inside surface <NUM> of the first cowl <NUM><NUM>, with the second pin <NUM> extending axially along a second axis <NUM>. In various embodiments, the second axis <NUM> is offset from the first axis <NUM>, as well as the first hinge line <NUM><NUM> of the first cowl <NUM><NUM>, similar to the arrangement described above with reference to <FIG>, <FIG>.

In various embodiments, a first hinge stop <NUM> is connected to the inside surface <NUM> of the first cowl <NUM><NUM> via the cowl flange <NUM> and a second hinge stop <NUM> is connected to the link <NUM> proximate the second end <NUM> of the link <NUM>. The connections of the first hinge stop <NUM> to the first cowl <NUM><NUM> via the cowl flange <NUM> and the second hinge stop <NUM> to the link <NUM> proximate the second end <NUM> of the link <NUM> are similar to those described above with reference to <FIG>. As illustrated, the second cowl <NUM><NUM> is pivotally secured to the fixed structure via a second dual axis hinge <NUM><NUM>, which includes each of the components described above with reference to the first dual axis hinge <NUM><NUM>. A cowl lock <NUM> is used to lock the first cowl <NUM><NUM> and the second cowl <NUM><NUM> in place while in the closed position. As described above with reference to <FIG>, several additional hinges, which may include conventional clevis and lug hinges, may be disposed along both the first hinge line <NUM><NUM> and the second hinge line <NUM><NUM> to pivotally mount, respectively, the first cowl <NUM><NUM> and the second cowl <NUM><NUM> to the fixed structure (e.g., to the pylon <NUM>).

As illustrated, when the first cowl <NUM><NUM> assumes the closed position, the first hinge stop <NUM> and the second hinge stop <NUM> contact one another. The manner of contact prevents an upper portion <NUM> of the first cowl <NUM><NUM> from moving or otherwise being displaced in a radial direction R in response to a load or a force F acting in a radial direction R on the inside surface <NUM> of the first cowl <NUM><NUM>, in a manner similar to that described above with reference to <FIG>. In various embodiments, the cowl lock <NUM> will be secured at a lower end <NUM> of the first cowl <NUM><NUM> in order to prevent the first dual axis hinge <NUM><NUM> from rotating about the first axis <NUM> or the first hinge line <NUM><NUM> in response to the load or the force F acting in the radial direction R on the inside surface <NUM> of the first cowl <NUM><NUM>. Referring to the second cowl <NUM><NUM>, once the cowl lock <NUM> at the lower end <NUM> of the second cowl <NUM><NUM> is released, the second cowl <NUM><NUM> is able to rotate about the second hinge line <NUM><NUM>. This enables the various hinges pivotally connecting the second cowl <NUM><NUM> to the fixed structure (e.g., to the pylon <NUM> or to the pylon flange <NUM>) to rotate about the second hinge line <NUM><NUM> such that the cowl may assume the open position.

Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships or physical couplings between the various elements.

Claim 1:
A cowl system for a nacelle of an aircraft, comprising:
a fixed structure (<NUM>); and
a cowl (<NUM>) pivotally mounted to the fixed structure (<NUM>) via a dual axis hinge (<NUM>), the dual axis hinge comprising:
a link (<NUM>) having a first end (<NUM>) and a second end (<NUM>);
a first pin (<NUM>) configured to pivotally secure the first end (<NUM>) of the link (<NUM>) to the fixed structure (<NUM>) and a second pin (<NUM>) configured to pivotally secure the second end (<NUM>) of the link (<NUM>) to a cowl flange (<NUM>) connected to and extending from an inside surface (<NUM>) of the cowl (<NUM>); and
a first hinge stop (<NUM>) connected to the cowl (<NUM>) and a second hinge stop (<NUM>) connected to the second end (<NUM>) of the link (<NUM>),
characterised in that:
the first hinge stop includes a first face (<NUM>) and the second hinge stop includes a second face (<NUM>) configured to abut the first face when the cowl assumes a closed position;
the manner of contact between the first face and the second face is configured to prevent an upper portion (<NUM>) of the cowl from moving or otherwise being displaced in a radial direction (R) with respect to the cowl in response to a load or a force (F) acting in the radial direction on the inside surface (<NUM>) of the cowl; and
a cowl lock (<NUM>, <NUM>) is configured to secure a lower end (<NUM>) of the cowl (<NUM>) in order to prevent the dual axis hinge (<NUM>) from rotating about a first axis (<NUM>) in response to the load or the force (F) acting in the radial direction (R) on the inside surface (<NUM>) of the cowl (<NUM>).