Plastic bottom diaphragm for aircraft seat

The design of passenger seats for aircraft requires consideration of passenger comfort, the number of seats and space limitations in a particular aircraft, and the location of the seat in the aircraft. Passenger seats generally include an 15 aluminum base frame assembly to which are attached reclining seat backs, center arm rest assemblies, fold-down food table assemblies, and fully upholstered seat back and bottom cushion assemblies.

20

In the past, the bottom cushion assembly of the individual passenger seat was supported by a conventional bottom diaphragm formed of an aluminum sheet that was riveted along its edges to the tops of the stretcher tubes between two of the spreaders. The riveted aluminum sheets were difficult 25 and time consuming to remove and replace. Other bottom diaphragms have been constructed of fabric or webbing which tends to wear out and fray.

U.S. Pat. No. 4,277,103 discloses a continuous sheet of aluminum shaped to establish a natural seat bottom depres- 30 sion to prevent pelvic rotation.

U.S. Pat. No. 4,630,864 issued Dec. 23, 1986 to Ian C. Toll discloses a seat diaphragm stiffened with a panel of structural foam and skinned with carbon fiber material.

Seat cushions for aircraft seats are generally made of soft, 35 open-cell, low density comfort foam, such as polyurethane. If floatation assistance is not required, the cushion may be constructed entirely of this type of open-cell foam.

If a bottom seat cushion is to provide a passenger with floatation assistance for emergency ditching, a portion of the comfort foam is generally replaced with a hard, closed-cell higher density floatation foam. Heretofore, replacing the comfort foam with floatation foam, made the cushions harder and less comfortable. Thus, it has often been the goal, when designing bottom cushions, to use only enough floatation foam to meet regulatory requirements. This has usually meant that the cushion contained multiple small pieces of floatation foam, placed around the underside of the cushion, in an effort to maximize the comfort foam.

Often seat design becomes a compromise of comfort versus floatation versus safety when placing the floatation foam in the cushion. The floatation foam has the ability to dissipate energy better than comfort foam when placed in the cushion to reduce the spinal impact energy that a passenger J5 receives during a crash.

Business class and first class seats can be provided with a console with personal storage compartments, compartments for cocktail trays, and the like. A first class sleeper seat may include additional features such as a video monitor, go an extendable leg rest, and other features for passenger comfort and convenience.

Economy or coach passenger seats are generally narrower and more densely spaced than business class or first class seats. Further, the seats of commuter aircraft are generally 65 closer spaced and more dense than seats for larger widebody international flights.

40

45

The spacing of spreaders and legs along the length of the stretcher tubes will vary for different types of seats and different seating arrangements. The position of legs on seats nearest the aisle and seats nearest the wall of the aircraft may vary depending upon the structural design of the aircraft, the number of seats in the row and the location of the row of seats in the aircraft. The connections between spreaders and stretcher tubes and between leg assemblies and stretcher tubes often vary depending upon the location of the spreaders on the stretcher tubes, the location of the legs on the stretcher tubes, and whether the seat is a front facing seat or a rear facing seat.

Heretofore, the construction and maintenance of aircraft seats has been very expensive because operations have been labor intensive. Furthermore, the size and shape of components of the seat vary depending upon the location of the installation in the aircraft, resulting in a multitude of parts that must be kept in inventory for proper maintenance. Periodic maintenance required on aircraft seats generally requires replacement or disassembly of the entire seat merely for replacing or installing a component in the seat assembly.

The important structural requirements for safety must be met and at the same time the airline operator needs to be able to easily and cost effectively maintain the seats. It is often necessary to change the seating configuration in the aircraft to meet different passenger and market needs. In the past, the assembly and disassembly of the seats has been a complicated, time consuming, and expensive process, often requiring that most of the seat support structure be disassembled in order to move or change the seating configuration. Furthermore, every reduction in the weight of the seats without reducing the structural integrity saves the airline fuel and reduces operating expenses.

SUMMARY OF THE INVENTION

A typical aircraft seat base frame supports the individual passenger seats. In general, the base frame has a plurality of leg assemblies for supporting a front horizontal stretcher member and a rear horizontal stretcher member. The front and rear stretcher members are typically tubular, having a circular cross-section with concentric inner and outer walls. However, the stretcher members can have other crosssections. A plurality of base frame spreaders maintain the front and rear horizontal stretcher members in parallel, spaced-apart relationship. Normally the back of a passenger seat is pivotally mounted between two of the spreaders, and a passenger arm rest is mounted to each spreader.

According to one aspect of the present invention, a bottom diaphragm for supporting the bottom seat cushion of an individual passenger seat is positioned between two of the spreaders and removably connected to the front and rear horizontal stretcher members. The diaphragm is preferably integrally formed of a composite or plastic material and has generally horizontally extending sleeve portions formed on the front and back thereof for removably mounting the diaphragm to the front and rear horizontal stretcher members. The sleeve portions are generally channel shaped for fitting over a portion of the stretcher members.

The diaphragm is adapted to be installed by "snapping" or "popping" lobes on the sleeves between the front and rear stretcher members. The material of the diaphragm is deformed during installation as it is pushed between the stretcher members, but it returns back to the original relaxed condition to "lock" between the stretcher members.

3

According to another aspect of the invention adapted for tubular stretcher members, the sleeves can be formed to have an open, semi-cylindrical structure adapted to extend around more than one-half the circumference of the stretcher tubes. Thus, the plastic material of the sleeves is deformed during 5 installation as it is pushed over-center of the stretcher tube, but it returns back to the original relaxed condition to "lock" onto the tubular member by encircling more than one-half the circumference of the stretcher tube.

The seat cushion assembly includes a floatation portion 10 constructed of buoyant material having a density less than the density of water. The floatation portion of the bottom cushion assembly is preferably configured to fit into a receptacle in the seat bottom diaphragm. To reduce the spinal impact energy that a passenger receives during a 15 crash, a block of hard, closed-cell floatation foam is positioned below a thick layer of comfort foam to provide passenger comfort while positioning the floatation foam below the spinal area of the passenger for dissipating spinal impact energy encountered by the passenger during a crash. 20 Providing a bottom diaphragm with a recess into which the floatation foam extends permits the use of a bottom seat cushion providing an optimum combination of passenger comfort, floatation and safety.

Accordingly, it is an object of the present invention to 25 provide an improved aircraft seat support structure in which the bottom diaphragm for the passenger seats can be quickly and easily mounted or removed from the rest of the support structure. It is another object of the invention to provide an improved aircraft seat support structure with a reduced 30 number of parts. It is an object of the invention to provide a seat support structure that is easy and cost effective to maintain. It is another object of the invention to provide an aircraft seat support structure that is capable of meeting the normal safety requirements while being lighter in weight. 35 These and other objects, aspects, and advantages of the present invention will be apparent to those skilled in the art upon reading the following detailed description of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated into and form a part of the specification to illustrate several examples 45 of the present invention. These drawings and the detailed description of the preferred embodiments serve to explain the principles of the invention. The drawings are only for the purposes of illustrating the presently preferred examples of how the invention can be made and used, and the drawings 50 are not to be construed as limiting the invention to only the illustrated embodiment of the invention. The various advantages and features of the present invention will be apparent from a consideration of the drawings, in which:

FIG. 1 is an exploded fragmentary perspective view of an 55 aircraft seat support structure, the bottom diaphragm and the seat cushion assembly being illustrated in exploded positions for clarity;

FIG. 2 is a top plan view of the first embodiment of the diaphragm shown in FIG. 1; 60

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a bottom plan view of the first embodiment of the diaphragm shown in FIG. 1; 65

FIG. 6 is a side elevational view, the other side being a mirror image thereof;

4

FIG. 7 is an enlarged fragmentary view of the front gripper portion of the bottom diaphragm;

FIG. 8 is an enlarged fragmentary view of the rear gripper portion of the bottom diaphragm; and

9 is a perspective view of an upside down bottom diaphragm according to one aspect of the second embodiment of the invention, which shows the mounting sleeves formed thereon.

Numeral references are employed to designate like parts throughout the various figures of the drawings.

DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENTS

Referring to FIG. 1 of the drawing, the numeral 10 generally designates a base frame assembly formed by a pair of stretcher tubes 20 and 22, joined by a plurality of removable spreader members 259 and a plurality of removable leg assemblies 15. As will be hereinafter described in detail, the bottom seat cushion assembly 70 of an individual passenger seat is supported by a seat bottom diaphragm 80 or 100. A first embodiment of the bottom diaphragm is generally designated by the numeral 80 in FIGS. 1-8 of the drawings and a second embodiment is generally designated by the numeral 100 in FIG. 9. The bottom diaphragm 80 or 100 is positioned between two of the spreaders 25 for supporting the bottom seat cushion assembly 70.

Referring to FIGS. 1 and 2, the bottom diaphragm includes a diaphragm body portion, for spanning space between the front and rear stretcher members 20 and 22, and front and rear gripper portions 94c and 96c detachably securing the body portion to the stretcher members. The gripper portions are configured so that they can accommodate possible leg assemblies positioned between the spreader members.

Each bottom diaphragm 80 and 100 is a critical element in the load path which must meet specified design criteria. Generally, the bottom diaphragm must be capable of supporting a downwardly directed load of approximately 1,500 pounds to meet minimum performance standards. This assures that the diaphragm will not fail if subjected to a force of 170 pounds (the assumed weight of a seated passenger) multiplied by 8.6 times the force of gravity.

Further, during crash testing, baggage under the seat tends to move upwardly. To accommodate baggage under the seat, each diaphragm 80 and 100 must be capable of carrying an uplift force of approximately 108 pounds (20 pounds times 5.4 G) to meet minimum performance standards.

Thus, the molded bottom diaphragms 80 and 100 are preferably configured to support and distribute a downwardly directed force of at least 1,500 pounds over stretcher tubes 20 and 22. Further, while being releasibly secured to stretcher tubes 20 and 22, each diaphragm preferably carries an upwardly directed force of at least 108 pounds without disengaging stretcher tubes 20 and 22.

The base frame 10 secures and supports one or more individual passenger seats (not shown) above the floor 12 of the aircraft cabin. As used herein for the purposes of description, the terms "front" and "rear" are with reference to the facing direction of the aircraft seat. It should be appreciated, however, that rows of seats are often mounted back-to-back and that the front of a seat may face the rear of the aircraft.

While a preferred embodiment of the base frame 10 is illustrated in the drawings, it should be appreciated that the diaphragm 80 or 100 and seat cushion assembly 70 can be used in combination with other base frame structures such as those disclosed in Howell et al. U.S. Pat. No. 4,229,040; Amthor et al. U.S. Pat. No. 5,069,505 and Beroth U.S. Pat. No. 5,224,755, the disclosures of which are incorporated herein by reference. 5

The base frame 10 has a plurality of leg assemblies 15 comprising a front leg structure that typically includes front leg 14, and a rear leg structure that typically includes rear leg 16. The front legs 14 and the rear legs 16 are connected and reinforced by angled struts 18 and bottom horizontal struts 10 19. Leg assemblies 15 are preferably of identical construction and need not be right or left handed. Further, leg assemblies 15 preferably have energy absorbing characteristics wherein through plastic deformation energy will be dissipated. The deformations are limited through the incor- 15 poration of stops to prevent deformation of the leg assembly beyond predetermined limits.

The front legs 14 support a front horizontal stretcher tube 20 above the cabin floor 12. Similarly, rear legs 16 support a rear horizontal stretcher tube 22 above the cabin floor 12. 20 The front horizontal stretcher tube 20 and the rear horizontal stretcher tube 22 are supported in parallel, spaced-apart relationship to one another. Normally the front stretcher tube 20 is positioned about 1.5 inches higher than the rear stretcher tube 22. Furthermore, the horizontal stretcher tubes 25 20 and 22 are oriented to be perpendicular to the facing direction of the aircraft seat, shown by arrow 13. The front legs 14 and rear legs 16 of the base frame 10 are releasable secured by track fittings 21, for example of the type disclosed in U.S. Pat. No. 5,058,829 to Paul R. Bentley, to 30 tracks 23 laid in the aircraft cabin floor 12.

In the illustrated embodiment, stretcher tubes 20 and 22 are of substantially identical construction and have concentric inner and outer walls and a circular cross-section. For the purposes of description, the circular cross-section of the stretcher tubes can be divided into top, bottom, and side quadrants. However, it should be appreciated that the stretcher members need not be identical and can be constructed with cross-sections of other shapes, such as elliptical, square, or rectangular. Stretcher tubes 20 and 22 are supported in leg stirrups 65 on leg assemblies 15. However, other methods of attachment known to those skilled in the art can be used.

Spreaders 25 are mounted to the front and rear stretcher 45 tubes 20 and 22 and provide additional structural support to maintain the stretcher tubes in parallel, spaced-apart relationship. Normally the back (not shown) of a passenger seat is pivotally mounted between two of the spreaders, and a passenger arm rest (not shown) is mounted to each spreader. 5Q The spacing of the spreaders 25 along the stretcher tubes 20 and 22 is adjusted to accommodate the width of a first class, business class, or coach seat.

Spreaders 25 can be connected to stretcher tubes 20 and 22 according to methods well known in the art. However, in 55 the preferred embodiment of the invention spreaders 25 are removably connected to stretcher tubes 20 and 22 to facilitate maintenance of the aircraft seats and changing the configuration of the aircraft seats.

According to the best mode presently contemplated, base 60 frame spreaders 25 are formed of a single piece of machine aluminum configured to facilitate removal of the spreader from stretcher tubes 20 and 22 without disassembly of the complete base frame 10. Spreaders 25 are preferably of substantially identical construction. Each spreader 25 has a 65 downwardly facing saddle 30 adjacent the front end thereof and a downwardly facing saddle 50 adjacent the rear end

40

thereof, saddles 30 and 50 resting on the upper quadrants of the stretcher tubes 20 and 22. The saddles 30 and 50 have recesses formed thereon to engage and receive the upwardly extending side walls of spreader stirrups 45 or leg stirrups 65. However, other methods of attachment known to those skilled in the art can be used.

Stirrups 45 and 65 engage at least the bottom quadrant of the stretcher tubes 20 and 22 and preferably encircle at least 180° of the circumference of stretcher tubes 20 and 22.

The front stretcher tube 20 preferably has a plurality of spaced-apart apertures 24 arranged in two diametrically opposed rows in the side quadrants of the tube 20. Each of the apertures 24 is formed to provide a passage through the front horizontal stretcher tube 20 to allow the passage of any suitable connector such as a screw, bolt, pull pin or the like through the body of the stretcher tube 20. The plurality of apertures 24 are aligned in parallel and in closely spacedapart intervals, for example spaced on 1.5 inch centers, along the length of the stretcher tube 20. When connected to the front legs 14, the front horizontal stretcher tube 20 is preferably oriented such that the apertures 24 are oriented in a substantially horizontal plane. Similarly, the rear horizontal stretcher tube 22 preferably has a plurality of apertures 26 arranged in two diametrically opposed rows in the side quadrants of the tube 22. Each of the apertures 26 is formed to provide a passage through the rear horizontal stretcher tube 22 to allow the passage of a screw, bolt, pull pin or other suitable connector through the body of the stretcher tube 22. The plurality of apertures 26 are aligned in parallel and in closely spaced-apart intervals along the length of the stretcher tube 22. When connected to the rear legs 16, the rear horizontal stretcher tube 22 is preferably oriented such that the apertures 26 are oriented in a substantially horizontal plane and front to rear.

If a spreader 25 is positioned vertically above a leg assembly 15, then the saddles 30 and 50 engage the upwardly extending side walls of leg stirrups 65 that support the stretcher tubes. Leg stirrups 65 support the horizontal stretcher tubes 20 and 22. Leg stirrups 65 are preferably integrally formed or welded onto front legs 14 and rear legs 16 of leg assemblies 15.

As illustrated in FIG. 1, in the preferred embodiment of the invention spreader stirrups 45 and leg stirrups 65 can be wider than saddles 30 and 50 on spreaders 25.

Further, saddles 30 and 50 on spreaders 25 are configured such that spreaders 25 and leg stirrups 65 do not interfere with one another, which significantly reduces the number of design variations for mounting legs at different locations on stretcher tubes 20 and 22. Saddles 30 and 50 and stirrups 45 and 65 are configured to carry and distribute force along stretcher tubes 20 and 22 to carry tension or compressive loading so that a single spreader design can be employed in a front or rear facing seat. Further, saddles 30 and 50 and saddle stirrups 45 and leg stirrups 65 are configured to increase the stiffness of stretcher tubes 20 and 22 by distributing force over a significant length of stretcher tubes 20 and 22.

Continuing to refer to FIG. 1, the bottom diaphragm 80 is removably connected to stretcher tubes 20 and 22 between two spreaders 25 for supporting the bottom seat cushion assembly 70 of an individual passenger seat. The seat cushion assembly 70 preferably includes a flotation cushion portion as will hereinafter be described in more detail Furthermore, the diaphragm 80 can also have a passenger life vest or other device releasibly attached to the bottom thereof.