Vent Structure

There are many cases where it is desired to control the flow of mediums, such as air, from one portion of a structure to another by restricting the flow thereof, yet provide means to reduce the restriction of flow during emergency conditions such as those which might otherwise produce enough force to fail the intervening structure. An example of this is in the floor of a wide-bodied aircraft wherein the relatively large volume of the cabin space above the floor must be vented to the space underneath the cabin floor when the underfloor volume is rapidly decompressed. If improperly vented, the relatively small differential pressure which can be developed across the cabin floor multiplied by the relatively large floor area can generate sufficient force to fail the floor and do structural damage to the aircraft. This problem has been recently recognized by governmental agencies who have promulgated regulations requiring means in aircraft to assure that a decompression in any compartment in an aircraft caused by a hole of at least 20 square feet can be safely accommodated. An obvious expedient to meet the requirement in such aircraft is to reinforce the floor so that it can withstand decompression loads structurally. However, such a solution is impractical in that it requires extensive retrofit of aircraft presently in service and increases the weight of the aircraft without a corresponding increase in efficiency, thus raising the overall cost of the aircraft to fly.

The prior art solution of providing simple blow-out panels cannot be used in most instances because their operation can be triggered by passenger applied forces. Another solution to the problem can be seen in a patent application by Robert G. McIntyre and Otto J. Minnich entitled "Frangible Aircraft Floor," U.S. Pat. Ser. No. 578,479 now U.S. Pat. No. 3,938,764 which was filed 19 May 1975, and is assigned to applicants' assignee. It has been used to provide venting through a floor structure without decreasing the useful load-carrying capacity of the aircraft. However, frangible floors cannot be used in all applications and, therefore, variable area vents which actuate automatically and are resistant to the tampering of passengers have been required.

The present invention includes a hingedly mounted vent panel which normally restricts the flow of air between the upper and lower portions of an aircraft fuselage. The restriction is required so that the ventilating, air conditioning and heating air flows of the aircraft can be controlled throughout the cabin. The hinged vent panel is retained in its normal position by a pair of hinged plates which are biased overcenter against stops and form one wall of a differential pressure sensing plenum chamber. Assuming that the upper portion of the aircraft fuselage is larger than the lower portion, the plenum chamber is pneumatically connected to remain at the pressure of the upper portion. When a rapid decrease in pressure occurs below the floor, a differential pressure is generated across the two hinged plates which causes them to move against the biasing means overcenter to release the support for the vent panel which then swings out of the way to a position which no longer restricts flow between the upper and lower portions of the aircraft fuselage. Once the emergency condition is over, the vent panel is pulled toward its original position until the biasing means snaps the hinged plates back into their vent panel supporting position.

Normal venting between the upper and lower portions of the cabin can occur through openings in the vent panel which are located below the hinged plates and these can also be used to relieve a differential pressure condition wherein the low pressure side is the upper portion of the fuselage. However, in some instances the air conditioning, heating and ventilating requirements are such that the restriction is so great that an unwanted differential pressure in the opposite direction can build up across the floor. For this reason flapper doors can be included in the hinged plates which blow upwardly during decompression of the upper portion of the fuselage to allow relief of the differential pressure without damage to the floor. This is normally not a critical situation, however, since the volume above the floor of a passenger aircraft is normally much greater than the volume below it.

It is therefore a principal object of the present invention to provide means for relieving differential pressures which may be undesirably applied across a structural wall or floor structure.

Another object is to provide venting means which automatically respond to predetermined differential pressure to open a larger-than-normal venting area for relieving a differential pressure.

Another object is to provide vent means which are economical to manufacture, easy to install, tamperproof and easy to reset after their use.

Another object is to provide vent means for an aircraft which blend in with the general decor of the aircraft and therefore do not unnecessarily alarm passengers.

Another object is to provide a vent structure which, upon application of a predetermined differential pressure, self actuates to open a large vent passageway.

Another object is to provide an emergency venting structure which opens in response to a sensed differential pressure but not in response to externally applied force.

These and other objects and advantages of the present invention will become apparent to those skilled in the art after considering the following detailed specification which discloses a preferred embodiment thereof in conjunction with the accompanying drawings wherein:

FIG. 1 is a cutaway perspective view of a portion of the side wall of an aircraft having the vent structure of the present invention installed therein;

FIG. 2 is a side cross-sectional view of the vent structure of FIG. 1 showing its position when it is called upon to vent large amounts of air from the lower portion of the aircraft fuselage to the upper portion;

FIG. 3 is a view similar to FIG. 2 wherein a differential pressure of a predetermined value has been established across the floor structure of an aircraft and the vent structure is beginning to open a large vent area; and

FIG. 4 is a view similar to FIGS. 2 and 3 wherein the vent panel has rotated out of the way to open a large vent area between the upper and lower portions of an aircraft fuselage to relieve pressure in the upper portion thereof.

Referring to the drawings more particularly by reference numbers, number 10 in FIG. 1 refers to a vent structure 10 installed in the interior wall 12 of an aircraft fuselage 14 adjacent the passenger compartment floor 16 which normally divides the upper fuselage volume 18 from the lower fuselage volume 20. The vent structure 10 is shown positioned and pneumatically connected for the case where the upper portion space 18 is larger than the lower portion space 20. Should the opposite be the case, the vent structure 10 could just as easily be installed below the floor 16 to protect the floor 16 from differential pressures thereacross with the high pressure being in the space 20. The normal case, however, is for the space 18 to be larger than the space 20 and therefore protection must be provided to prevent differential pressure across the floor 16 with the high pressure in the space 18 due to a rupture of the fuselage integrity below the floor 16.

Air conditioning, heating, and ventilating needs in most aircraft require that restricted flow occurs throughout the passenger compartment or upper fuselage space 18 during the flight. Therefore, the vent structure includes a vent panel 22 which may include small vent orifices 24 to allow a selected quantity of air to pass therethrough and through suitably open floor members 26 hidden therebehind. The vent orifices 24 are usually covered by decorative means such as the grille 28 shown.

The vent structure 10 can be connected to the structure of the aircraft by any suitable means such as structural side extensions 30 which connect to adjacent structure 32 or by upwardly extending extensions 34 such as are shown in FIG. 2 which connect the structure 10 to the interior wall 12. Any other suitable connection means can also be used.

The vent panel 22 is connected to a shell member 36 by means of a piano-type hinge 38 which allows the vent panel 22 to swing back toward fuselage wall 39. The rotation of the vent panel 22 about the hinge 38 is normally prevented by a pair of plates 40 and 42 which are connected together by a piano-type hinge 44. In addition, plate 40 is connected to the vent panel by means of the piano hinge 46 and the plate 42 is connected to the shell 36 by means of another piano hinge 48. Suitable biasing means such as the spring 50 urge the plates 40 and 42 toward vent stops which may be the separate stops 52 and 54 connected respectively to the vent panel 22 and the shell 36, or the stop member 56. The stop member is shown connected to plate 40 in position to bear against plate 42 to prevent further movement of the plates 40 and 42 in the direction caused by the biasing spring 50 when the structure 10 is in the position shown in FIG. 2. This, of course, is also accomplished by the stops 52 and 54 which bear against plates 40 and 42 respectively with included abutment surfaces 55 and 57.

The plates 40 and 42, the shell 36, the portion of the vent panel 22 above hinge 46 and the opposite side walls such as the side wall 58 shown form a plenum chamber 60. The formulation of the plenum chamber 60 may be assisted by suitable seals incorporated into the edges of the plates 40 and 42 and the panel 22 or by providing a suitable resilient sealing material 61 on the sidewalls 58. The plenum chamber 60 is pneumatically connected to the upper portion space 18 by means such as the orifice 62 through the panel 22 and the grille 28. Therefore, the pressure in the plenum chamber 60 remains very close to the pressure in the upper portion space 18.

There are some times when the pressure below the floor 16 needs to be relieved into the space 18. Therefore, optional flapper doors 64 may be provided which, in conjunction with mating holes 66 in the plates 40 and 42 enable a flow upward through the plates 40 and 42 as shown by the arrows 68 in FIG. 2. The doors 64 are lightly spring-loaded closed by means of springs 70 so that they normally remain in the closed flow obstructing condition shown in FIGS. 1, 3 and 4.

When a differential pressure is established with the high pressure area above the floor 16, the differential pressure is also applied across the plates 40 and 42. As shown in FIG. 3, when the differential pressure reaches a predetermined amount to overcome the preload in the spring 50, the plates 40 and 42 start to rotate away from the stops whether they be stops 52 and 54 or stop 56. This movement eventually drives the plates beyond the overcenter, a location shown by the phantom hinge line 72 in FIG. 3. From this point on, the spring 50 causes further folding of the plates 40 and 42 which removes the structural bracing of the vent panel 22 pulling it toward the fuselage wall 39 to remove the flow restriction and allow a large flow of air indicated by the arrows 74 in FIG. 4. It should be noted that as the vent panel 22 moves toward the shell 36, a dust member 76 is pulled from under a resilient covering 78. The member 76 is required to prevent small fingers, hands, toys, fluids and, in addition, dust from undesirably falling beneath the floor 16. The member 76 can be connected to the vent panel by means of a hinge 80 so that it does not extend into the venting area to unnecessarily restrict the venting flow. The dust member 76 also restricts flow when the vent structure 10 is in its normal position so that the orifices 24 properly meter the flow of air conditioning, heating, and other desirable flows during normal operation of the aircraft. Alternately, a large cover member 78 could be used instead of the dust member 76. However, as the arrows 74 show, a large percentage of the flow is along the floor 16 and anything disrupting the flow in this area results in a disproportionate flow restriction when the vent structure 10 is open.

It should be noted that although the vent panel 22 is self actuating once the hinge 44 goes past the point 72, such need not be the case and in suitable circumstances the flow itself can push the panel 22 out of the way.

Once there is no longer need for emergency venting, the panel 22 can be moved from the position shown in FIG. 2 back to the position shown in FIG. 2 by merely pulling it toward the passenger compartment until the two plates 40 and 42 snap into their proper overcenter position in readiness for the next emergency.

Thus, there has been shown and described a novel vent structure which is suitable for providing emergency venting between the upper and lower portions of an aircraft fuselage and which fulfills all of the objects and advantages sought therefor. Many changes, alterations, modifications, and other uses and applications of the subject vent structure will become apparent to those skilled in the art after considering this specification and the accompanying drawings. All such changes, alterations, uses and modifications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.