Aircraft equipment support

An equipment support for attaching equipment to an aircraft comprises a gripper foot having a T-shaped slot that engages a track mounted to the aircraft floor. The gripper foot is mounted to a trunnion mount that enables the gripper foot to rotate freely about a vertical axis so that the gripper foot can negotiate curves along a non-linear track. The trunnion mount is mounted to the equipment support frame by means of a horizontal pivot. The horizontal pivot is held against rotation below a predetermined load by a torque-resisting element. If the floor track is warped, for example during a crash, the twisting loads transmitted from the floor track to the gripper foot overcome the torque-resisting element, which allows the trunnion mount and gripper foot to rotate with the floor track thereby allowing the gripper foot to remain attached to the track without imparting excessive loads on the track, gripper foot, or equipment support frame.

BACKGROUND OF THE INVENTION

The present invention relates to adjustable supports for aircraft interior equipment, in particular, adjustable supports for aircraft seating and the like.

According to the General Aviation Crash Worthiness Project of the National Transportation Safety Board (“NTSB”), incidents of severe injuries and fatalities in survivable crashes of the general aviation fleet could be significantly improved by the use of energy absorbing seats and occupant restraints. According to one study conducted by the NTSB, many of the seats in the general aviation fleet broke or come off the seat tracks during survivable crashes. In one study, 44% of the occupied seats involved in general aviation crashes became detached from the airplane structure, usually because the seat feet or legs broke or separated. In one case the seat came loose, which allowed the occupant, who had survivable injuries, to fall out of the airplane and drown in shallow water. In another case, the seat frame collapsed allowing the rear legs to move closer to the front legs which allowed the rear of the seat to rotate down accelerating the occupant toward the floor.

In addition to failures caused by the seat structure itself, floor warping due to collapsing of the airframe can cause seats to fail. As the aircraft floor warps, extra stresses are placed on the seat feet as the seat resists changing its original shape to accommodate the floor warp. Floor warping can also be caused by excessive side loads imparted to the seat by deceleration other than along the longitudinal axis of the aircraft. For example, with a misalignment of only ten degrees, a 9-g forward acceleration can create a side load of 1.2 g on the seat feet.

Prior art aircraft seating has addressed the need for the seat to remain attached to the floor in spite of floor warping in a number of ways, including through the use of a flexible seat frame such the Piper Aircraft, Inc.'s “S-tube” seat. Another aircraft seat capable of accommodating floor warping includes a thin “fin” machined between the side structure of the seat and the track gripper. The fin flexes to accommodate the warping of the floor while maintaining the track gripper in contact with the seat track. What is needed, however, is an aircraft seat capable of accommodating floor warping during a crash that is also capable of moving along a non-linear seat track as is required in modern aircraft.

SUMMARY OF THE INVENTION

The present invention comprises a support for securing aircraft interior equipment such as a seat to the floor of an aircraft. According to an illustrative embodiment, the equipment support comprises a gripper foot having a T-shaped slot that engages the track mounted to the aircraft floor. The gripper foot is mounted to a trunnion mount that enables the gripper foot to rotate freely about a vertical axis so that the gripper foot can negotiate curves along a non-linear floor track. The trunnion mount is then mounted to the equipment support frame by means of a horizontal pivot. The horizontal pivot, however, is locked against rotation by one or more torque-resisting elements such as shear pins or friction locks that are designed to release at a predetermined load.

In normal operation with the trunnion mount locked in position, the gripper foot remains vertical as it is moved along the floor track. If, however, the floor track is warped, for example during a crash, the twisting loads transmitted from the floor track to the gripper foot overcomes the resistance of the torque-resisting element(s), which allows the trunnion mount and gripper foot to rotate with the floor track thereby allowing the gripper foot to remain attached to the track without imparting excessive loads on the track, gripper foot, or equipment support frame.

DETAILED DESCRIPTION

The drawing figures are intended to illustrate the general manner of construction and are not necessarily to scale. In the detailed description and in the drawing figures, specific illustrative examples are shown and herein described in detail. It should be understood, however, that the drawing figures and detailed description are not intended to limit the invention to the particular form disclosed, but are merely illustrative and intended to teach one of ordinary skill how to make and/or use the invention claimed herein and for setting forth the best mode for carrying out the invention.

As noted hereinbefore, survivability of crashes in general aviation is enhanced when aircraft seating remains attached to the aircraft floor despite floor warping due to collapse of the fuselage. As shown inFIG. 1, a prior art aircraft seat frame10accommodates warping of the aircraft floor and with it seat track12by providing a “fin”14between seat frame16and gripper foot18which allows gripper foot18to twist relative to frame16without imparting undue stress on frame16or gripper foot18.

With reference toFIGS. 2-5, aircraft equipment support20, which may be used, for example to support an aircraft seat22to a non-linear seat track42comprises a gripper foot24which is attached to a trunnion mount26by means of a vertical pivot28. Vertical pivot28allows gripper foot24to rotate freely about a vertical axis58relative to trunnion mount26. In the illustrative embodiment, vertical pivot28comprises a bolt30and a stop nut32which in cooperation with bushing34retain gripper foot24to trunnion mount26while permitting gripper foot24to rotate freely about vertical pivot axis58.

Gripper foot24comprises a substantially bell-shaped body having a T-shaped slot36formed at the mouth end. T-shaped slot36includes a lower surface38that is disposed above the upper surface40of seat track42. Claw portions44and46of the T-shaped slot36of gripper foot24curve underneath and are disposed in a parallel spaced-apart relationship to lower surface48of the horizontal flange portion50of seat track42.

In the illustrative embodiment, gripper foot24further includes a wheel52mounted to a wheel shaft54which is mounted to gripper foot24so that the longitudinal axis56of wheel shaft54lies in a common plane with a vertical pivot axis58of the vertical pivot28. Wheel52provides for low rolling friction as gripper foot24moves across upper surface40of the horizontal flange portion50of seat track42enabling seat22to be quickly and easily moved into position. Wheel52may be mounted to wheel shaft54by any conventional means including plain bearing, needle bearing, or ball bearing. Optionally, wheel52can be omitted in favor of a low sliding friction pad (e.g., PTFE or UHMWPE) in which case lower surface38of gripper foot24would directly engage upper surface40of horizontal flange portion50rather than being disposed above upper surface40.

With particular reference toFIG. 4, trunnion mount26is attached to seat frame60by means of pivot shaft62and pivot shaft64which are rigidly attached against rotation (e.g., by splines, pins, etc. to trunnion mount26. Pivot shaft62and pivot shaft64freely rotate in bores66and68formed in seat frame60about horizontal pivot axis80. Horizontal pivot axis80and axis56of wheel shaft54lie in a common plane, which minimizes the torque on pivot shaft62and pivot shaft64caused by side loads on wheel52. Although trunnion mount26is free to rotate relative to seat frame60, trunnion mount26is constrained against rotation by means of shear pins70and72which are inserted in corresponding bores74,76passing through seat frame60and pivot shafts62,64. Shear pins70and72are designed to fail at a predetermined torque exerted on pivot shaft62and pivot shaft64for reasons explained more fully hereinafter.

In normal operation, trunnion mount26is held rigidly by shear pins70and72while gripper foot24is free to pivot about vertical axis58. This enables equipment support20to be moved from a first linear section82of seat track42to a second linear section84of seat track42through a curved section86of seat track42. With reference toFIG. 5, however, if seat track42is twisted, for example as a result of the aircraft floor warping, shear pins,70and72shear at a predetermined load, which enables trunnion mount26to rotate relative to seat frame60thereby allowing gripper foot24to remain attached to seat track42without transmitting undue bending loads to seat frame60. This enables seat22to remain attached to seat track42during a crash even if the floor is warped due to collapse of the aircraft fuselage thereby protecting the occupants in a survivable crash.

With reference toFIG. 6, in an alternative embodiment120of an aircraft equipment support incorporating features of the present invention gripper foot124supports a wheel152mounted to a wheel shaft154. Gripper foot124is mounted to trunnion mount126by means of a vertical pivot128and bushing134, which allow gripper foot124to freely rotate about vertical axis158. Vertical pivot128may be a conventional bolt or carriage bolt, but for reasons more fully explained hereinafter, vertical pivot128comprises a shoulder screw130secured with a stop nut132. Use of a shoulder screw130enables gripper foot124to freely rotate about vertical pivot128without binding while at the same time permitting shoulder screw130to be drawn tightly against seat frame160.

Trunnion mount126has a substantially J-shaped cross section rather than the U-shaped cross section of the embodiment of the embodiment ofFIGS. 1-5. Consequently, trunnion mount126is attached to seat frame160by means of a single pivot shaft164which is integrally formed as part of trunnion mount126. Pivot shaft164is free to rotate in bore166formed in seat frame160about horizontal pivot axis180. Horizontal pivot axis180and axis156of wheel shaft154lie in a common plane, which minimizes the torque on pivot shaft164caused by side loads on wheel152. Although trunnion mount126is free to rotate relative to seat frame160, trunnion mount126is constrained against rotation by means of the frictional engagement between shoulder screw130and seat frame160. The magnitude of the frictional engagement in the embodiment ofFIG. 6is adjustable in situ, since it is a function of the coefficient of friction and the torque applied to stop nut132.

In normal operation, trunnion mount126is held rigidly by shoulder screw130, while gripper foot124is free to pivot about vertical axis158. This enables equipment support120to be moved through the curved section86of seat track42. If seat track42is twisted, for example as a result of the aircraft floor warping the frictional engagement between shoulder screw130and seat frame160is overcome. Shoulder screw130then slides laterally in the elongated hole136, formed in seat frame160. This action enables trunnion mount126to rotate relative to seat frame160thereby allowing gripper foot124to remain attached to seat track42without transmitting undue bending loads to seat frame160. As with the embodiment ofFIGS. 1-5, this enables equipment support120to remain attached to seat track42during a crash even if the floor is warped due to collapse of the aircraft fuselage thereby protecting the occupants in a survivable crash.

Although certain illustrative embodiments and methods have been disclosed herein, it will be apparent from the foregoing disclosure to those skilled in the art that variations and modifications of such embodiments and methods may be made without departing from the invention. For example, in the illustrative embodiment the seat track has a substantially I-shaped cross section (with a T-shaped upper portion), other seat tracks with C-shaped, T-shaped or other cross sections are contemplated within the scope of the invention. Additionally, although in the illustrative embodiment, trunnion mount is prevented from rotating about the horizontal axis by shear pins or friction locks, other means of locking trunnion mount against rotation below a predetermined threshold such ball detents, sprag clutches and/or resilient members are contemplated within the scope of the invention. Accordingly, it is intended that the invention should be limited only to the extent required by the appended claims and the rules and principles of applicable law. Additionally, as used herein, unless otherwise specifically defined, the terms “substantially” or “generally” when used with mathematical concepts or measurements mean within ±10 degrees of angle or within 10 percent of the measurement, whichever is greater.