Mounting system for a nacelle fire detection system

A mounting system for a fire detection system for a turbofan engine propulsion system is provided to mount fire detection sensors on the inner fixed structure (IFS) of the nacelle. The mounting system mounts to an inner, engine facing surface of the IFS. Two IFS halves cooperate to form a substantially enclosed space around an engine core. The mounting system includes part of a fastening system mounted to the IFS, and an orientation clip mounted to a thermal blanket. Brackets for mounting the fire detection system sensing wires are positioned on the orientation clip, and the fastening system fixes the bracket to the IFS and traps the thermal blanket therebetween.

BACKGROUND

A typical aircraft turbofan propulsion system includes a jet engine (also called an engine core, or simply a core), a nacelle that surrounds the engine core, and a fan driven by the engine that draws in a flow of air that is split into a bypass airflow and an engine core airflow. The nacelle defines a bypass duct that surrounds the engine core. The bypass airflow is transported through the bypass duct and exits the bypass duct at a high speed at an aft end thereof. The engine core includes a multi-stage compressor to compress the engine core airflow, a combustor to add thermal energy to the compressed engine core airflow, and a turbine section downstream of the combustor to produce mechanical power from the engine core airflow. The mechanical power from the turbine section drives the compressor and the fan. After exiting the turbine section, the engine core airflow exits through an exhaust nozzle at the aft end of the engine.

Surrounding the engine core is a fire zone in which elevated temperatures must be quickly and reliably detected so that, in appropriate conditions, fire suppression can be employed, or other action taken to ensure the safety of the aircraft.

A fire detection system typically includes one or more thermal detectors, or other types of sensing elements, to provide a warning during engine operation if excess temperatures are detected or other conditions indicative of a fire are detected. The sensing elements are attached to a mounting system, which is attached either to the nacelle, to the engine core itself, and/or to an engine support structure. The sensing elements are suspended away from the surface of the nacelle, the engine core, or the support structure by a mounting system such that the sensing elements detect the conditions in an air space between the engine core and the nacelle.

The spacing of the sensing elements away from the engine core or support structure competes for space also used by other components. In addition to the fire detection system, the space between the engine core and the nacelle is filled with a multitude of components such as valves, tubes, ducts, wires, generators, gearboxes, sensors, etc. In many installations, the space between the engine core and the nacelle is further limited by the need to provide a thermal blanket surrounding all or part of the engine core. The thermal blanket provides thermal and acoustic insulation during engine operation. In many installations, such as nacelles constructed with composite panels, the thermal blanket might be necessary for shielding the composite panel from engine operating temperatures that could damage the composite panel.

A compact and light weight mounting system is desired for mounting the fire detection system in accordance with aircraft regulations and operating requirements, while also ensuring simplicity and accuracy of the installation/assembly and allowing flexibility in the placement of the mounting system components.

SUMMARY

According to an aspect of the invention, an assembly is provided for a propulsion system that include a jet engine housed within a nacelle. The assembly includes a thermal blanket and a bracket orientation clip. The blanket is configured to at least partially surround the engine. The blanket is also configured to thermally shield at least a portion of the nacelle from heat energy radiated by the engine. The clip includes a base and a plurality of anti-rotation tabs. The base is bonded to the blanket, and the tabs extend out from the base and away from the blanket.

According to another aspect of the invention, an assembly is provided for a turbofan propulsion system that includes a jet engine and a nacelle. The assembly includes a blanket and a fire detection system. The blanket is configured to thermally insulate at least a portion of the nacelle from the engine. The fire detection system includes a sensing wire, a bracket and an orientation clip that is bonded to the blanket. The bracket is configured to locate the sensing wire a distance from the blanket. The clip is arranged between the blanket and the bracket. The clip is configured to limit or substantially prevent rotation of the bracket relative to the blanket.

According to still another aspect of the invention, another assembly is provided for a turbofan propulsion system that includes a jet engine. The assembly includes a nacelle, a blanket, a clip, a bracket and a fastening mechanism The blanket is configured to arrange between at least a portion of the nacelle and the engine. The clip is bonded to the blanket, and includes a base and a plurality of tabs that are connected to the base. The bracket is nested with the clip laterally between at least some of the tabs. The fastening mechanism connects the bracket to the nacelle.

The clip may be configured to limit or substantially prevent rotation of the bracket relative to the blanket and/or the nacelle.

The assembly may include an inner fixed structure for the nacelle, and a fastening mechanism. The fastening mechanism may connect the bracket to the inner fixed structure.

The assembly may include a locating feature configured with the inner fixed structure. The fastening mechanism may be connected to the locating feature.

The assembly may include a mounting block connected to the bracket and supporting the sensing wire.

The base may be welded to the blanket. The base may also or alternatively be adhered or otherwise bonded to the blanket.

The base may be configured as or otherwise include a generally rectangular and/or flat portion of the clip.

The tabs may be respectively arranged at corners of the base.

The base may extend laterally between a pair of the tabs.

The assembly may include a bracket for a fire detection system. The clip may be arranged between the blanket and the bracket. The clip may be configured to limit or substantially prevent rotation of the bracket relative to the blanket.

The bracket may be nested with the clip laterally between a pair of the tabs.

The assembly may include a fastening mechanism for connecting the bracket to the nacelle. The fastening mechanism may project through the bracket, the clip and the thermal blanket. The fastening mechanism may be configured as or otherwise include a rivet, or a head connected to a threaded sleeve, or any other type of fastener.

The assembly may include a mounting block connected to the bracket. The mounting block may be configured to support a sensing wire for the fire detection system.

The assembly may also include a second mounting block connected to the bracket. The second mounting block may be configured to support a second sensing wire for the fire detection system.

The assembly may include a second mounting block connected to a second mounting bracket for the fire detection system. The second mounting block may be configured to support a second sensing wire for the fire detection system. The clip may be arranged between the blanket and the second bracket. The clip may be configured to limit or substantially prevent rotation of the second bracket relative to the blanket.

Other features and advantages of the present invention should be apparent from the following description of the preferred embodiments, which illustrate, by way of example, the principles of the invention.

DETAILED DESCRIPTION

FIG. 1is a side schematic view of a jet engine114(e.g., an engine core) enclosed within a nacelle100to form a turbofan propulsion system. The engine114is supported from a wing110of an aircraft by pylon structure112. An inlet cowl116of the nacelle100is located at a forward end of the nacelle100. A fan cowl118surrounds a turbine fan which compresses and accelerates the incoming air stream. A thrust reverser120is configured at an aft end of the nacelle100to help slow the aircraft upon landing. A thrust reverser panel or sleeve122slides along a path defined by one or more beams on the thrust reverser120. When the thrust reverser panel122is deployed upon landing, it causes thrust from the engine114to be diverted and partially reversed so that aircraft speed is reduced.

FIG. 2is a perspective view of the engine114and the nacelle100from the aft end looking forward. For simplification and a better view, several components are not shown such as the fan, the fan cowl, the inlet cowl, and the right half of the thrust reverser120. The left half202of the thrust reverser120is shown in a raised position. The left half202includes an inner surface which faces the engine114formed in the inner fixed structure (IFS)206of the left half202. The thrust reverser120left half and right half are closed during flight, forming a substantially enclosed shell around the engine114with the left half IFS and the right half IFS. Sensors of fire detection systems208,210are mounted on the inner surface of the IFS206of the nacelle.

FIG. 3is a side view of the inner surface of the IFS206shown inFIG. 2, showing the fire detection system mounted thereon in accordance with the embodiments disclosed herein. The aft end is to the left of the drawing, the forward end is to the right of the drawing.

FIG. 4is a perspective view of a fire detection system400.FIG. 4shows that the fire detection system400may include spaced-apart mounting blocks402through which sensing wires404are passed. As described further below, the sensing wires404are located at a position that is a predetermined distance from the nacelle by support assemblies406,408,410,412. The support assembly406may be configured as a double-bracket arrangement that supports two pairs of the sensing wires404and corresponding mounting blocks402. The support assembly408may be configured as a single-bracket arrangement that supports a single pair of the sensing wires404and corresponding mounting blocks402. The support assemblies410and412may each be configured as a bracket that supports additional wires and connections for the fire detection system, as well as a single wire and connection.

FIG. 5is a perspective view of a sensor assembly500that includes a pair of mounting blocks402and a double-bracket arrangement406such as those illustrated inFIG. 4.FIG. 5shows that the mounting block402may be generally cylindrical in shape, with the sensing wire404passing out from each end of the cylinder. A mounting bracket510holds the mounting blocks402in fixed position and facilitates mounting the sensor assembly500to a support assembly, described in more detail below. The sensor assembly500may be mounted to the support assembly using, for example, a fastener512such as a screw or the like.

FIG. 6is a perspective view of a single-bracket support assembly600in accordance with the embodiments disclosed herein. The support assembly600includes a bracket orientation clip602on which is placed a bracket604. The bracket604has a planar surface606with a bore607formed therein and sized to receive a fastening mechanism (described in more detail below). When the fire detection system is attached to the IFS, the retainer urges the bracket against the aircraft IFS (see, e.g.,FIG. 9). The bracket604includes an attachment surface608configured to receive a sensor assembly500and its associated mounting bracket510. The attachment surface608is offset from the planar surface606so that the attachment surface608is a predetermined distance away from the IFS when the bracket assembly600is installed. For example, inFIG. 6, a connecting portion614joins the attachment surface608to the planar surface606such that the attachment surface608is substantially parallel to the planar surface606and spaced away at a predetermined distance.

The spacing distance of the attachment surface608from the IFS is selected so that when the support assembly600is coupled to the IFS at the planar surface606, the attachment surface608is spaced away from the IFS by a predetermined distance. The connecting portion614shown inFIG. 6joins the planar surface606to the attachment surface608at an angle, generally forming a Z-shape when viewed in cross-section. The connecting portion614, however, may be provided in different shapes. For example, a curved shape may be used in place of the flat portion between the planar surface606and attachment surface608, or more convoluted shapes may be used, as desired for an application and operating regimen.

Referring toFIG. 7, the orientation clip602includes a substantially planar, four-sided flat portion702(e.g., a generally rectangular base) with raised tabs704,706,708,710(e.g., anti-rotation tabs) at approximately each corner. The flat portion702extends laterally between a first set of the tabs704and706and between a second set of the tabs708and710, which is longitudinally separated from the first set of the tabs704and706.

Referring now toFIG. 6, the flat portion702includes an opening712that aligns with the bore607of the bracket604when assembled and installed. An opposed pair of the raised tabs (e.g.,704and706) may limit or substantially prevent rotation of the bracket604on the orientation clip602when a torque is applied to the fastening mechanism (e.g., fastening mechanism810ofFIG. 8), such as when the assembly600is installed The fastening mechanism may be configured as or otherwise include, for example, a retainer such as a threaded screw and nut combination, or the like. Limiting or preventing rotation of the bracket604when a rotational force is applied to the fastening mechanism and, in turn, the bracket, during installation improves the ease of installation. For example, the orientation clip602can help ensure that during installation the bracket604is placed in the proper orientation and position relative to the IFS. The orientation clip602also can assist in using the support assembly to hold down and maintain a thermal blanket (not shown) in position, as described further below. The bracket604and its associated tabs also allow for precise positioning of the sensor assembly on the IFS.

FIG. 8is a perspective view of a support assembly800with dual brackets in accordance with embodiments disclosed herein, which is configured similar to the dual bracket assembly406ofFIG. 4. The support assembly800includes a first support bracket802and a second support bracket804, each of which supports a sensor assembly510. Respective flat portions806,808of the two support brackets802,804are overlapped on the orientation clip602. Alternatively, support brackets802,804may be fabricated as a single support bracket. A fastening mechanism810attaches the brackets802,804to the IFS (not shown). Further details of the fastening mechanism810for attaching the support assembly800to the IFS may be understood with reference toFIG. 9.

FIG. 9is a cross-sectional side view of the support assembly406,800illustrated inFIGS. 4 and 8, installed on an IFS812. The left bracket802and the right bracket804are coupled to the IFS812by a fastening mechanism900and hold a thermal blanket901in place relative to the IFS812. This thermal blanket901may surround and provide thermal and/or acoustic insulation for some or all of the engine core. The thermal blanket901, for example, may shield composite panels of the nacelle from relatively high operating temperatures of the engine core. The thermal blanket901may have a flexible sheet-like body with a heat reflective surface that faces the engine. The thermal blanket901may include a single layer or multiple layers of materials bound together between face sheets (e.g., metal foil sheets). The thermal blanket901may also or alternatively include a core of fibers arranged between the face sheets. The thermal blanket901may be constructed from metal and/or any other suitable material. Various thermal blankets are known in the art, and the present disclosure is not limited to any particular thermal blanket types or configurations. Furthermore, the thermal blanket901illustrated inFIG. 9is optional, and may be included or omitted depending on the aircraft requirements.

The fastening mechanism900includes a location feature attached to the IFS812, the location feature including a base portion902and a stud or pilot portion904. The base portion and stud portion are typically provided as a single one-piece structure, but may be separately provided. When installed, such as illustrated inFIG. 9, the stud portion904extends outwardly from the plane of the IFS812and provides a locating feature or pilot guide that aligns with the bore807of each bracket802,804. A sleeve portion906and head portion908fit over the stud904. The sleeve portion906and head portion908may be configured as, for example, a rivet or threaded cap that fits over the stud portion904. The stud portion904may be threaded, such as when it is provided as a screw or bolt, in which case the sleeve portion906will be internally threaded and may be screwed down onto the stud portion904. If the stud portion904is not threaded, then the sleeve portion906fits over the stud portion904with a mechanical or friction fit, such as the case with a rivet that is crimped in place to prevent movement. Examples of a suitable base portion and stud portion may include one or more of the fastening products available from Click Bond, Inc. of Carson City, Nev., USA.

When the sleeve portion906and head portion908are coupled to the location feature that includes the base portion902and stud portion904, in an installation configuration such as illustrated inFIG. 9, the sleeve portion906and head portion908are effectively coupled to the IFS812. In this way, the fastening mechanism900urges both of the brackets802,804toward the IFS812, and the attachment surface of each bracket is held at a position that is a predetermined distance from the IFS812when the support assembly is in the installation configuration.

The orientation clip602may be attached to the thermal blanket901by welding, epoxy adhesive, or any other bonding technique known to those skilled in the art. A typical welding technique involves applying electrical energy through the orientation clip602to the adjacent surface of the thermal blanket901, which melts or otherwise fuses the orientation clip602and thermal blanket901together at approximately the location of the applied electrical energy. When the orientation clip602is fixedly bonded to the IFS812, then the clip establishes the location and orientation for mounting brackets604, etc., to be mounted to the IFS812.

FIG. 10is a perspective view of a support assembly1000in accordance with an embodiment. The support assembly1000includes a bracket1002and an attachment portion1004. In theFIG. 10embodiment, the attachment portion1004is configured as an upturned end of the substantially planar bracket1002. Two sensor cradles1006,1008are attached to opposing sides1004a,1004bof the attachment portion1004. These sensor cradles1006and1008are biased so that they will hold or secure in each of the cradles a mounting block402or a sensor wire404. A fastening mechanism1010includes a locating feature, such as a stud or bolt, that aligns the bracket1002and holds the bracket1002to the IFS (not shown) so that the attachment portion1004is a predetermined distance from the IFS. As noted above, the fastening mechanism1010can include a stud and rivet combination, as illustrated inFIG. 10, or may include a cap and bolt combination, or the like. InFIG. 10, a cap portion1012and sleeve portion1014of the rivet are visible.

FIG. 11is a plan view of the bracket1002illustrated inFIG. 10.FIG. 11shows the top planar surface1104of the bracket, as well as a bore1106sized to receive the locating feature of the fastening mechanism1010(seeFIG. 10).

FIG. 12is a cross-sectional side view of the support assembly1000illustrated inFIG. 10installed to the IFS812and holding a thermal blanket901in place. The support assembly1000is illustrated inFIG. 12in an installed configuration, held to the IFS812by a fastening mechanism900as described above and illustrated inFIG. 9.

FIG. 13is a plan view of a support assembly1300constructed in accordance with embodiments disclosed herein. The support assembly1300includes a substantially planar bracket1302with an attachment surface1304. A plurality of sensor cradles1306,1308,1310and1312are attached to the bracket1302and receive a variety of sensors1314,1316,1318. The support assembly1300is coupled to the IFS by one or more fastening mechanisms1320; e.g., through-fasteners.

FIG. 14is a cross-sectional side view of the connector assembly illustrated inFIG. 13, showing the mounting of the support assembly1300to the IFS812with the fastening mechanisms1320. The fastening mechanisms1320each includes a locating feature such as a base portion1402and a stud or pilot portion1404, which is coupled to the aircraft IFS812. The locating feature aligns with a bore (see, e.g.,FIGS. 15-17) of the bracket1302. As noted, the base portion1402and pilot portion1404are typically provided as a single one-piece structure, but may be separately provided. When installed, such as illustrated inFIG. 14, the pilot portion1404extends outwardly from the plane of the IFS812and provides a locating feature or pilot guide that aligns with the bore of the bracket1302. In theFIG. 14embodiment, a threaded cap or rivet is used to urge the bracket toward the IFS812. More particularly, an insert portion1406fits into the pilot portion1404. The insert portion1406is topped at one end with a head portion1408and the two may be configured as, for example, a rivet or threaded cap that fits over the pilot portion1404. The pilot portion1404may be internally threaded, in which case the insert portion1406will be threaded and may be screwed down into the pilot portion1404. If the insert portion1406is not threaded, then the insert portion1406fits into the pilot portion1404with a mechanical or friction fit, such as the case with a rivet that is crimped in place to prevent movement. Examples of a suitable base portion and stud portion may include one or more of the fastening products available from Click Bond, Inc. of Carson City, Nev., USA.

FIG. 15is a cross-sectional side view of a support assembly embodiment that fastens a sensor bracket1514to the thermal blanket901and the IFS812with a fastening mechanism1502comprising a stud and nut combination. The structures illustrated inFIG. 15are not drawn to scale; rather, some dimensions of the structures are exaggerated for purposes of illustration. A nut1504and washer1506are threaded onto a stud portion1508of a bolt or pilot guide1510having a head1512at the opposite surface of the IFS812. It should be apparent that the nut1504can be replaced by a threaded cap. A sensor bracket1514is urged toward the IFS812and against an orientation clip1516by the fastening mechanism1502. The sensor bracket1514includes a bore1518sized to receive the stud portion1508, which provides a locating feature of the fastening mechanism1502. An optional grommet1520may be provided to provide easier placement of the thermal blanket901over the stud portion1508.

FIG. 16is a cross-sectional side view of a support assembly embodiment for use without a thermal blanket, attached to the IFS812with a stud and nut combination. The structures illustrated inFIG. 16are not drawn to scale; rather, some dimensions of the structures are exaggerated for purposes of illustration. The support assembly is attached to the IFS812with a fastening mechanism1602including a stud and nut combination. A nut1604and washer1606are threaded onto a stud portion1608of a bolt or pilot guide1610having a head1612at the opposite surface of the IFS812. A bracket1614is urged toward the IFS812by the fastening mechanism1602. The bracket1614includes a bore1618sized to receive the stud portion1608, which provides a locating feature of the fastening mechanism1602.

FIG. 17is a cross-sectional side view of a support assembly embodiment for use without a thermal blanket, attached to the IFS812with a fastening mechanism comprising a rivet configuration. The structures illustrated inFIG. 17are not drawn to scale; rather, some dimensions of the structures are exaggerated for purposes of illustration. The support assembly is attached to the IFS812with a fastening mechanism1702configured as a rivet combination. A rivet cap1704is crimped onto a rivet stud portion1708having a head1710at the opposite surface of the IFS. As known to those skilled in the art, the rivet combination1702may be installed by mechanically deforming an end of the stud portion1708, or through other similar crimping techniques for installing a rivet. A bracket1712is urged toward the IFS812by the fastening mechanism rivet1702. The bracket1712includes a bore1718sized to receive the rivet stud portion1708, which provides a locating feature of the fastening mechanism1702.