Overhead Opening Plug Door

Abstract

An overhead opening plug door for a pressurized aircraft cabin wherein the door is counterbalanced for manual emergency opening in event of power failure, yet the door is easily closed and sealed in normal operation. Power actuated cables move the door, which is roller mounted on tracks of nonconstant curvature, by means of push-pull rods and cam linkages into open and closed position.

Description

BACKGROUND OF THE INVENTION

In aircraft capable of high-altitude flights the cabin is pressurized for the comfort of the passengers. This subjects the inner faces of the cabin doors to air pressure loads. Obviously, if a door were constructed to open outwardly and the door latch were inadvertently released in flight, the air-pressure differential would cause the door to fly open in midair. To preclude the occurrence of such an accident, doors of a plug-in-type are used. One such door is described in U.S. Pat. No. 3,085,297 issuing Apr. 16, 1963 to Hal R. Linderfelt for "Door for Pressurized Cabin." The structure of this door required it to move inwardly, pivot, and then swing outwardly to fully open position. The plug door of the present invention, however, is of the overhead opening type to avoid a requirement of door hinge clearance.

Vertically moving doors of the type comprising the present invention are heavy and require power assistance in moving them upwardly. In event of power failure they must be manually operable to open. Usually strong counterbalance springs assist in this operation. However, to close and seal the door requires considerable effort in opposition to these springs.

SUMMARY OF PRESENT INVENTION

The overhead opening plug door comprising the present invention has rollers for movement along nonconstant curvature tracks which impart an inward and upward direction to the door as it is opened by power-actuated cables. Cam linkage between the cables and the rollers on the door cause the door to be moved into and from its sealed closed position at a minimum expenditure of force and energy. The stress and strain on the fuselage structure is not transmitted to the door structure because of its looseness of fit yet the door is effectively sealed and retained in its closed position in flight.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of an aircraft showing the approximate location of ingress and egress doors;

FIG. 2 is a perspective view with portions broken away showing a door in overhead position over the door entranceway;

FIG. 3 is a schematic illustration showing the cable and linkage which actuates the door;

FIGS. 4 and 5 are elevational views of alternate embodiments partly in section to show the linkage structure and the door in several positions;

FIG. 6 is a perspective view of the upper rollers, bellcrank and upper end of the push-pull rod;

FIGS. 7 and 8 are perspective views of alternate forms of lower rollers and linkages; and

FIG. 9 is an elevational view showing the cable actuating mechanism.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring now to FIG. 1 there is shown a side view of a commercial transport aircraft 10 having a pair of engines 12 mounted on wings 14. A third engine 16 is mounted on the tail section 18. The fuselage 20 has four access passenger doors 22, 24, 26 and 28 on each side, for a total of eight doors. The latter six doors are of the same contour and are identical except for local mechanism adjustment and the two forward doors, because of the aircraft configuration, will be left- right-hand construction.

Door 24 is illustrative of the rest and is shown in FIG. 2 in its raised position above door jamb 30. Tracks 32 of nonconstant curvature extend upwardly on both sides of the door opening and are adapted to receive rollers 34 which are attached to the door 24 to carry it between its open and closed positions. Motor 36 mounted to rotate shaft 38 is the power source for moving a cable 40 which, in turn, moves the door either up or down. Counterbalance springs 42 oppose the weight of door 24 to facilitate manual movement of the door to open position when necessary. As can be observed from the eight-across seating and the size of the fuselage, the door 24 appears to be large and heavy.

In FIG. 3 there is shown the door 24 having an upper support shaft 44 and lower support shaft 46 rotatably mounted and extending horizontally from the sides of the door. Affixed to each end of shaft 44 is a bellcrank 48 having rollers 50 on long arm 52 to engage a track, not shown. These rollers are mounted on a roller support 54 pivotally mounted on arm 52 of bellcrank 48. Continuous cable 40 is attached to the roller support 52 and constitutes the power means for moving the door 24 up and down. Cable 40 extends over pulleys 56, 58 and over a power drum 60 which is actuated by motor 36 to move the door.

The short arm 62 of bellcrank 48 is connected to lower bellcrank 64 by a push-pull rod 66. This bellcrank 64 is mounted on lower shaft 46 with the push-pull rod 66 attached to the short arm 68 of the bellcrank. In the illustration in FIG. 3 the bellcrank 64 has a pair of long arms 70 with roller supports 72 pivotally mounted thereon. Each support 72 has rollers 74 which engage door jamb tracks, not shown.

In operation in moving door 24 upwardly the motor 36 exerts an upward pull on cable 40. This causes bellcrank 48 to rotate clockwise in FIG. 3 until shaft 44 is in line with the direction of pull on cable 40. This moves the top of the door inwardly somewhat but not enough to clear the upper header 76 of the door opening. This also places an initial tension on push-pull rod 66, imparting a counterclockwise rotation on arm 68 of lower bellcrank 64. This in turn will cause rollers 74 to react on the trackway, not shown, to cause the door to move inwardly prior to its upward movement.

Continued upward force on cable 40 causes more reaction of the rollers 74 and translates the tension on push-pull rod 66 into compression because the rod tends to move upwardly faster than the upper bellcrank 48. This imparts further rotation on the bellcrank and thus camming the upper portion of door 24 further inwardly prior to vertical movement. Thereafter further pull on the cable 40 moves the door to its overhead position.

In the lowering of the door 24 the reverse action takes place. The motor 36 pulls the cable 40 downwardly in opposition to the action of the counterbalance springs 42. The door then moves downwardly with the aid of gravity (the doors weigh approximately 300 pounds) and is not allowed to oscillate due to the configuration of the lower bellcrank in the four-bar linkage system on the door. As the lower bellcrank 64 approaches the lower end of the track, not shown, rotation of the bellcrank is induced by the lower track curvature, causing the lower end of the door to close into the door opening. This rotation applies tension on push-pull rod 66, which in turn rotates upper bellcrank 48 clockwise about its support 54 at the end of long arm 52. This moves the upper part of the door into the door opening.

The sectional views in FIG. 4 and FIG. 5 show alternate embodiments of linkage structure for operation in the manner just described. Briefly, the upper and lower bellcranks are reversed and the physical construction of the lower bellcranks differ. In FIG. 4 there is shown a door opening between the top door jamb 76 and the bottom 78. Door 24 is shown in its closed position with the rollers 74 on lower bellcrank 64 at the bottom of track curvature 80. Tracks 82 extend upwardly on both sides of the door jamb with a nonconstant curvature, providing a cam surface for the bellcranks 48 and 64 to move the door 24 inwardly when it is pulled upwardly. Bellcranks 48 and 64 carry door 24 by pivot shafts 44 and 46 and are connected by push-pull rod 66 as shown. As the door is pulled upwardly it first moves inwardly to the position shown by phantom line 24A. In this position the push-pull rod is shown as 66A, lower bellcrank as 64A and upper bellcrank as 48A. The door's uppermost position is shown as 24B. In lifting the door 24 in FIG. 4 the force on push-pull rod 66 is converted from compression to tension whereas in the embodiment shown in FIG. 5 the force is converted from tension to compression.

Before describing the embodiment in FIG. 5, reference is had to the bellcranks 48 in FIG. 6 and 64 in FIG. 7. These bellcranks are used in the embodiment shown in FIG. 4. In FIG. 6 there is shown bellcrank 48 mounted on the top pivoting shaft 44. This bellcrank has a short arm 62 connected to the top end of push-pull rod 66. A longer arm 52 extends angularly from the short arm and has a roller support 54 pivotally mounted thereon. This support is an elongated mounting at the ends of which spaced rollers 50 are rotatably positioned. The ends of cable 40 are also attached to each end for pulling the support 54 up or down along the roller tracks. This movement of support 54 along the tracks 82 upwardly (see FIG. 4) initially applies a compression force on push-pull rod 66 until pivot shaft 44, and door 24, swings outwardly. Thereafter the continued upward pull on the bellcrank provides a tension on the push-pull rod, causing the lower bellcrank to drive the lower end of the door inwardly and upwardly.

As shown in FIG. 7 lower bellcrank 64 is mounted on the end of shaft 46 and has a short arm 68 to which the lower end of push-pull rod 66 is pivotally attached. The longer arm 84 terminates in an integral crossbar 86 to form a "T-bogie" having rollers 74 mounted at each end. This T-bogie provides a camming action on the tracks which by analogy may be compared to that of a carpenter's crowbar. The cooperation of the curved lower portion 80 of track 82 in FIG. 4 with the rollers 74 on each end of crossbar 86 is such that compression on push-pull rod 66 causes the lower portion of the door to move inwardly and subsequent tension on the rod 66 pulls the lower part of the door upwardly.

In the embodiment shown in FIG. 5 the sequence of application of compression-tension forces is reversed because the direction of the short arms of the bellcranks point inwardly of the fuselage from their pivot points on the door instead of outwardly as shown in FIG. 4. When the door is raised from closed position the upward pull on arm 52 of bellcrank 48 places tension on push-pull rod 66 and lifting force on the short arm 68 of the lower bellcrank. The relationship of the long arms 70 with rollers 74 with the curvature of the lower end 80 of track 82 is such that the lower end of the door swings inwardly and upwardly, converting the tension on push-pull rod 66 into compression, moving the top of the door inwardly and upwardly.

Although the lower bellcrank shown in FIG. 4 and FIG. 7 may be used in the embodiment shown in FIG. 5, the bellcrank shown in FIG. 8 is considered to be an improvement in its operation. Here the short arm 68, to which push-pull rod 66 is attached, is mounted on the lower door pivot shaft 46. A pair of diverging long arms 70 are also affixed to shaft 46. The outer ends 88, 90 are connected by crossmember 92 for structural support. Roller supports 72 are pivotally mounted to the ends 88 and 90 of arms 70. A pair of rollers are mounted on each end of each support 72. In this configuration the crossmember 92 compares with the crossbar 86 in FIG. 7 and each roller support 72 with its four wheels 74 replaces each pair of rollers in FIG. 7. This results in a smoother jamproof operation and, accordingly, is preferred to the bellcrank in FIG. 7 for use in both embodiments in FIGS. 4 and 5.

A sectional view of track 82 may be seen in FIG. 8. This track consists of a U-shaped channel with inturned lips 94 between which roller supports 72 may pass. The outer rollers 74 fit within the slot recess 96 are are prevented from having lateral movement therewith. Shafts 98 and 100 are constructed so as to permit lateral movement between the bellcrank arms 70 and the rollers 74. This compensates for slight lateral misalignment of the tracks on the door jamb on installation. Track 82 also has a grooved portion 102 in which cable 40 may be carried.

In FIG. 9 there is shown the power apparatus for moving the door. Motor 36 rotates shaft 38 on which is mounted a drive gear 102. A power pulley drum 60 has a gear 104 connected to gear 102 by a drive chain 106. Counterbalance spring 42 is mounted over spring drum 108 with end 110 fastened thereto by pin 112. The other end 114 is attached to rotatable plate 116 by pin 118 which is adapted to rotate with power pulley 60 through shaft 120. As the door is moved down to closed position the spring 42 tightens up so that it may assist in raising the door when such action is desired.

Having thus described the foregoing embodiments, modifications will readily occur to those skilled in the art and it is to be understood that such modifications also are to be considered as part of this invention.

Claims

We claim:

1. An overhead plug door comprising:

a door with top and bottom laterally extending rotatable shafts thereon,

bellcranks on each of said shafts,

said bellcranks on each shaft having arms thereon interconnected with a push-pull rod whereby rotational movement of one bellcrank and shaft causes rotational movement of the other bellcrank and shaft,

said bellcranks having other arms with spaced apart rollers thereon,

door jamb tracks engageable with said rollers,

said tracks having a nonconstant curvature whereby movement of said rollers along said track rotates said bellcranks and said shafts and hence the roller position on said track determines the position of said door relative to said tracks,

said rollers on said bellcranks on said top shafts being pivotally connected thereto and said rollers on said bellcranks on said bottom shafts being fixedly mounted thereon, and

lifting means secured to said upper rollers at points offset from the plane of said door in the closed position thereof, said upper bellcranks pivoting said door toward an in-line position with said upper rollers when a lifting force is exerted by said lifting means, whereby pivoting of said upper bellcrank causes said fixedly mounted rollers at the bottom of said door to react with said tracks to move the bottom of said door relative to said tracks.

2. An overhead plug door as set forth in claim 1 wherein said tracks are curved near the bottoms thereof to move said door into and out of a doorway opening between said tracks.

3. An overhead plug door as set forth in claim 1 wherein said tracks guide movement of said door between closed position within an opening defined by said door jamb and an open position overhead.

4. An overhead plug door as set forth in claim 1 wherein a force applied to an arm of one of said bellcranks along said tracks imparts a rotational movement on said bellcrank and associated movement of that portion of said door to which said bellcrank is pivotally mounted,

said push-pull rod imparting a similar movement to the other of said bellcranks to move that portion of said door to which said other bellcrank is associated, said push-pull rod responding to movement of said other bellcrank to further rotate the first of said bellcranks.

5. An overhead plug door as set forth in claim 1 wherein at least one of said bellcranks has an arm with an integral crossbar with rollers mounted on the ends thereof.

6. An overhead plug door as set forth in claim 1 wherein at least one of said bellcranks has an arm with a roller support pivotally mounted thereon.

7. An overhead plug door as set forth in claim 1 wherein at least one of said bellcranks includes a pair of interconnected arms, each of which has rollers mounted thereon.

8. An overhead plug door as set forth in claim 7 wherein each of said arms has a roller support pivotally mounted thereon with rollers mounted at each end of said roller support.