Aircraft decompression vent assembly

Abstract: An air return grille for an aircraft mounted below the passenger cabin sidewall comprises openings to allow return airflow from the air conditioning system. In a preferred embodiment, the grille openings are covered by a single thin baffle 32 with cutouts within its periphery that slip over and are held in place by fasteners on the molded grille 28. The thin baffle 32 is affixed to the molded grille 28 along one or more edges on the grille. All other thin baffle 32 attachments allow for the baffle to be disengaged upon the onset of a rapid decompression. During normal operation, the thin baffle 32 restricts flow through a small opening in the grille. During a sudden/rapid decompression of the cargo compartment/lower lobe, the baffle is dislodged from the fasteners and forced into a position parallel to the airstream. This allows the airflow to pass through all of the molded grille 28 openings in order to achieve rapid pressure equalization.

Description: TECHNICAL FIELD OF THE INVENTION This invention relates to vent systems used for controlling return airflow and rapid decompression airflow within the fuselage of commercial aircraft, particularly those commercial aircraft known as "wide bodies." BACKGROUND OF THE INVENTION As is well known in the aircraft industry, rapid decompression in an aircraft can have disastrous consequences. Such decompression can result from leaving a cargo door ajar, failing to lock the door properly, or if a rupture of the aircraft skin occurs for any reason. Also, during normal operations there is a need to provide a return air path within the environmental control system for conditioned air to be circulated within the aircraft cabin and cargo areas. Accordingly, a large number of air grilles are provided in an aircraft to serve a dual purpose, i.e., delivery of fresh air, and, in an emergency, to allow for the rapid movement of very large quantities of air during decompression. Such air grilles also are desired to reduce noise in the aircraft by blocking airflow noise from coming through the grilles during normal operations. See, for example, the U.S. Patent 5,137,231 by Boss, that is assigned to the assignee of this invention. The original design requirements for this vent design include the need for a large effective opening (approximately 600cm 2 (100 in 2 )) for lower lobe decompression. In addition, a small effective opening (approximately 60cm 2 (10 in 2 )) must be provided for main cabin decompression. The vent must provide this effective opening within fractions of a second (approximately 40 msec) at a very low pressure differential (approximately 15 psig) upon the onset of a rapid decompression. The small effective opening is also required for the normal air return flow from main cabin to lower lobe. The small opening creates a pressure drop that yields a direct air return flow through the vent assembly. Problems with most prior art air grilles are in their noise production complexity, weight, cost, cleaning, and maintenance. See also, U.S. Patent No. 3,854,567 by Roach, U.S. Patent No. 4,432,514 by Brandon, and U.S. Patent Reissue No. RE 32,554 by Murphy, each of which discloses a decompression panel having actuatable openings and spring valve means for relieving a pressure differential between an aircraft cabin and the cargo compartment. This invention pertains to a vent assembly for use in aircraft and solves the problem of having to use heavy, mechanically complex and expensive vents for controlling return airflow and rapid decompression airflow within the fuselage of commercial aircraft. Prior attempts in solving the regulation of return airflow and rapid decompression airflow have resulted in the creation of heavy and expensive assemblies made of many diverse parts. Previous designs have relied on complex mechanical features, such as pivoting louvers hinged door/gates, and multiple baffles, for controlling the airflow. These prior vents are very costly because of the high recurring cost associated with assembling them. These assemblies have also required extensive adjustments in order to achieve the desired airflows. US-A-5137237 discloses: an aircraft decompression vent assembly ; a molded grille attached to an aircraft; a thin baffle which is attached to said grille; and retention means allowing said baffle to become partially separated from said during rapid decompression The large number of baffles in this prior art assembly have to be installed either during manufacture or later on in the aircraft, in both cases requiring cumbersome manual labour. SUMMARY OF THE INVENTION The above noted problems are solved by the device according to claim 1. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described more fully in the following detailed description in conjunction with the attached drawings, in which: FIGURE 1 is a cutaway side elevation of the passenger cabin of a commercial aircraft with four decompression vents in place beneath the windows. FIGURE 2 is a more detailed showing of two decompression vents and the normal return air flow from the passenger cabin to the cargo compartment. FIGURE 3 is a cutaway side elevation view of the cabin sidewall showing two decompression vents with normal return airflow taking place. FIGURE 4 is a cutaway side elevation view showing rapid decompression in its initial stages. FIGURE 5 is an isolated isometric view of a decompression vent in initial stages of decompression. FIGURE 6 is an isometric view of a decompression vent in its normal upright position. FIGURE 7 is a rotated isometric view showing details of the baffle and screw retention. FIGURE 8 is an expanded isometric view of a releasable retention means for attachment of a thin baffle to a molded grille. FIGURE 9 is an expanded cross-sectional view of a threaded boss and screw for attachment of the thin baffle to a molded grille. FIGURE 10 shows a cross-sectional view with a screw installed to attach a think baffle to a molded grill. FIGURE 11 is an expanded view similar to that of FIGURE 8 except that there are no perpendicular cut lines on the thin baffle. FIGURE 12 is an expanded cross-sectional view similar to FIGURE 12 except there is a washer shown in position to secure a thin baffle to a grille. FIGURE 13 shows a cross-sectional view similar to FIGURE 10 except that a washer is included in FIGURE 13. DESCRIPTION OF A PREFERRED EMBODIMENT FIGURE 1 shows an aircraft sidewall 10 and four of the decompression vents 16 of this invention as they are installed in an aircraft passenger cabin. Seats 12, windows 14, decompression vents 16, and a floor support angle 18 are attached to the floor beams. The two forward seats have been removed to aid visibility behind the forward seats, FIGURE 2 shows normal, non-decompression, low velocity airflow 20 moving from the passenger cabin 22 enroute to the cargo compartment 24 below. In this "normal" mode of operation, the decompression vents serve to circulate passenger return airflow, utilizing only several of the lower louvers of molded grille 28. As will be seen in the Figures to follow, the upper louvers are blocked by the thin baffle in this "normal" mode of operation. Twenty bosses 40 are installed on each molded grille 28 and serve to connect the molded grille 28 to the thin baffle 32 as will be shown on further Figures. FIGURE 3 is an isometric drawing showing the back side of the decompression vent 16. FIGURE 4 is an isometric drawing showing the backside of a decompression vent 16 during rapid decompression as shown by the airflow direction indicators 26. As will subsequently be more apparent, the thin baffle 32 is no longer attached to the molded grille 28 except at the upper row of bosses 40 and retention fasteners. FIGURE 5 shows details of the molded grille 28 which is held in place by multiple latches 30 while the thin baffle 32 is shown to be partly disconnected from the molded grille 28 to allow unrestricted airflow during rapid decompression from the passenger cabin to the cargo compartment. FIGURE 6 shows a molded grille 28 with retention and release means for 34 and means 35 for permanently attaching the thin baffle 32 to the molded grille 28. FIGURE 7 shows the baffle 32 held by retention and release means 34 on the back of the grille 28. Retention means 34 such as standard screws engaged into the molded grille 28. In the event of a sudden loss of pressure in the cargo compartment 24, the resulting pressure differential across the grille 28 forces the small holes with cuts 38 within the thin baffle 32 to be dislodged from the screw heads (retention features) 34 and to be displaced away from the airstream. The preferred embodiment includes a grille having a rectangular planar baffle which includes slits and holes manufactured using a blanking dic. The holes are 0.51 cm (.20 inches) in diameter and have four slits that are 0.89 cm (.35 inches) in length as measured from the center of the hole. The baffle 32 is a laminate comprised of vinyl films about 0.03 mm (.001 inches) thick and layers of aluminum foil 0.08 mm (.003 inches) thick and adhesive. FIGURES 8, 9, and 10 show the retention and release means 34, which, in this embodiment, retains the thin baffle 32 attached to the boss 40 of the molded grille 28 by a screw 42. A cut 44 and a circular hole 33 have been made in the thin baffle 32 to ease the assembly of the parts. FIGURES 11, 12 and 13 show the same parts as FIGURES 8, 9, and 10 except that FIGURES 11, 12 and 13 do not have cuts extending through its circular hole and a washer is used to secure the fastener to prevent any movement during the service life of the aircraft. It should be apparent that the intent is to allow all but one row at the top of the thin baffle to be disconnected to allow full venting under decompression loads. The fastener installation of FIGURE 10 is designed to allow the pressure loading of a rapid decompression to pull out and disconnect the thin baffle from the fasteners of FIGURE 10.

Claims: An aircraft return air vent/decompression panel assembly comprising a molded grille (28) for covering a return air vent in an aircraft and a flexible baffle (32) releaseably attached to the downstream side of the grille and covering a portion thereof, wherein the baffle (32) has a plurality of holes therein and four slits (38) extending outward from each hole; the grille (28) has a plurality of headed fasteners attached to the downstream side thereof, and (38) the position and size of the holes, slits (38), and fastener heads are adapted so that the fastener heads protrude through the holes in the baffle (32) during normal flight operations, and the baffle (32) at least partially releases from the grille (28) upon a rapid decompression event. The assembly of claim 1 wherein the headed fastener is a screw (42). The assembly of claim 1 or 2 wherein the baffle (32) is a laminate comprised of a vinyl film and aluminum foil. The assembly of claim 1, 2 or 3 wherein the baffle (32) is fixedly attached to the grill (28) along a top edge. The assembly of any of claims 1-4 which additionally comprises at least one headed fastener near a top edge of the baffle (32) adapted to fixedly attach the baffle (32) to the grille (28) at that position. The assembly of any of claims 1-4 wherein the baffle (32) has a plurality of horizontal rows of holes adapted to fit over a corresponding number of rows of headed fasteners on the grille (28) and one row of holes and fasteners along a top edge of the baffle (32) are adapted to fixedly attach the baffle (32) to the grille (28) along said row. The assembly of claim 6 wherein the baffle (32) is fixedly attached to the grille (28) along said row with washers (53) and screws (52) secured to the grille (28).

Inventors: WEBER JOSEPH G, WEBER, JOSEPH G.
Applicants: BOEING CO, THE BOEING COMPANY
Application year: 1998
Main classification: B64C1
IPC codes: B64C1