Lightweight chair

A lightweight seat suitable for applications such as those in which the seat and occupant must withstand extreme amounts of applied force during use, e.g., encountering high waves in boats of seven meters (23 feet) or greater at speeds of at least 20 knots (37 km/h (or 10.3 m/s)).

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 61/490,775 filed May 27, 2011.

TECHNICAL FIELD

This application concerns lightweight seats for environments where the occupant is subjected to substantial random and/or sudden dynamic forces, e.g. buffeting, pounding, bouncing and the like.

BACKGROUND

High-performance vehicles subject their occupants to substantial random and/or sudden dynamic forces, and therefore the seats in which such occupants sit during motion must be extremely rugged in design and performance. An example is the seats suitable for high-speed, rugged marine craft such as rotationally molded boats in very large dimensions (e.g., seven meters (23 feet) or greater). The occupants of such seats must withstand extreme amounts of applied force during use, e.g., encountering high waves in boats of seven meters (23 feet) or greater at speeds of at least 20 knots (37 km/h (or 10.3 m/s)). At the same time, weight is always a concern in high-performance vehicles and, of course, the seat must be comfortable.

SUMMARY

A preferred embodiment of a lightweight seat is illustrated in the accompanying Figures and described below. This is only an example to illustrate the principles of the invention. The seat proper is mounted on a pedestal and base which has a permanently or temporarily inflated air bag to provide cushioning and, in the preferred embodiment, approximately 4 inches of vertical clearance to absorb forces and therefore moderate motion of the seat. A keyway or equivalent feature prevents the seat from pivoting around the vertical axis. Two rings help maintain the performance of the air bag.

The lightweight seat is particularly suitable for use with the Widmer Flex-Ride Night Raider, a boat having a plastic hull which flexes and absorbs impacts produced at high speeds in rough water because the impact G-forces are absorbed by the hull instead of directly translated to the occupants. The lightweight seat disclosed here further absorbs such forces instead of translating them to the occupants, and it does so at a substantial reduction in weight, which is a critical parameter in the design of an effective boat of this type and for this application.

DETAILED DESCRIPTION

General

While this application describes a seat for the preferred application of a rotationally molded boat other water-borne vehicles, those are only examples. Turning to the figures, in general terms assembly100comprises a base1mounted to the hull or deck of the boat (perhaps through an intermediate mounting system not shown) using mounting holes11or other features supporting the connection. For example, if threaded nuts or similar features are molded into the boat, the seat may be bolted to the boat though the mounting holes11. Other means for attachment are equivalent. By way of example only, six mounting holes11are provided in base1, only three of which are visible inFIG. 1.

Turning briefly toFIG. 6, a pedestal12(not visible inFIGS. 1-5) is mounted or molded into the base1. The seat2is mounted into central opening13formed in the pedestal12combination.

Returning toFIGS. 1-5, the seat2is preferably a single molded piece (not considering any stiffening members which may be molded into it), generally L-shaped in profile and contoured according to conventional principles. Either or both sides of the seat may have optional armrest(s)5that may be formed by a pin-and-socket arrangement (for example) so that they may be folded up or down as desired. It is desirable for purposes of reducing weight and material usage, and to ensure sufficient flow of the material during molding, that one or more openings be molded into the seat.

In general, the components of the base1and seat2are rotationally molded polymers or marine-environment-suitable metals. Materials are selected based on a sufficient balance of cost, strength, weight, ease of handling, and the like. Preferred molding materials for high performance watercraft and similar applications are high density cross-linked polyethylenes (HDXLPE), which are commercially available. Other materials known to be suitable for rotational molding may also be used, including the less costly (but less strong) high density polyethylenes (HDPE) which are also commercially available. The base1has a preferred thickness of 0.156 inch and preferably a sandblasted finish, but those are only examples.

A permanently or temporarily inflated air bag4surrounds the pedestal12to provide cushioning and, in the preferred embodiment, approximately 4 inches of vertical clearance to absorb forces. The air bag4is generally similar to that described in U.S. Pat. No. 4,560,145 (Widmer), the entire contents of which is incorporated by reference. In general, the air bag is an inflatable member made of a flexible material, having a uniform thickness and comprising a plurality of annular sections. The sections sequentially taper in diameter to form a generally pyramidal shape. The air bag may be inflated by conventional means, e.g., as described in the Widmer '145 patent incorporated by reference.

Two rings6,7(FIGS. 2-4) help maintain the performance of the air bag. The upper and lower rings, one between each pair of adjacent sections of the air bag, extend around the outside of the air bag to provide annular support between the sections and to control bulges and stretching. The rings provide support without the danger of the inflatable member “thinning” in the ring area when inflated. “Thinning” of the inflatable member could result in a rupture or bulge. Each ring has a circular cross section. Preferred dimensions for the O-rings are 10.47 inch (26.6 cm) and 11.21 inch (28.5 cm) diameter for the upper and lower rings, respectively, each being 0.5 inch (1.27 cm) in cross-sectional diameter.

Turning toFIG. 7, viewed from the side in cross-section, the air bag4has three generally toroidal sections21,22,23stacked above and connected to each other, and a smaller cylindrical section24stacked above and connected to the uppermost section23of the three toroidal sections. The bottom and top faces25,26are generally flat to accommodate the upper flat surface of the pedestal and the lower surface of the annular region of the underside of the chair, respectively. The central portion27of the air bag is generally cylindrical and has an inner diameter profile corresponding to the outer diameter profile of the pedestal. That profile can be understood as being a series of four cylindrical portions, the first (lowest) and third portions27a,27chaving inwardly (proceeding in the upward direction) sloping sides and the second and fourth (highest) portions27b,27dhaving vertically straight sides (e.g., right circular cylinders). The transitions between such sections are beveled or rounded as appropriate, as are the lower and upper ends of central portion27. Each of the two transitions28a,28bwhere two immediately adjacent toroidal sections join together defines upper and lower necks around the outer surface of the air bag. These locations are where the upper and lower O-rings6,7are located. These locations correspond to the locations of the top of pedestal12and shoulder32cdiscussed further below.

In terms of materials, the air bag4is constructed from polymer such as a suitable elastomer, e.g., a vinyl plastic of about 70 durometer on the A scale. The O-rings6,7are made of elastic or elastomeric material, such as neoprene rubber, for example in the range of 80 durometer. As noted above, in the preferred embodiment illustrated in the Figures, the air bag4provides approximately four inches of cushioned vertical travel in the preferred embodiment.

Turning toFIG. 8, base1is a preferably a single piece but can be an assembly of multiple pieces if desired (although strength and performance may suffer). As illustrated, it comprises a plate section30defining a pair of straight, downward-opening channels31that may be used to adjust its position relative to the boat deck or hull. The pedestal12is axially symmetric and generally conical, extending above the flat plate section30. The air bag4described above is mounted around the pedestal, and the seat2described above is mounted (above the uppermost surface of the air bag4) above the pedestal12. As the cross sectional view illustrates, the inner and outer faces32,33of the pedestal12need not be identical, and in the preferred embodiment they have surface profiles which are not similar to each other (i.e., they are not “parallel” to each other) at all. The inner face32is generally a pair of axially aligned right circular cylinders32a,32b(although the lower32ais slightly tapered in the preferred embodiment illustrated). The diameter of the upper32bis less than that of the lower32a, producing a shoulder32cwhere they meet. The outer face33has three axially concentric sections, a lowermost section33abeing more noticeably tapered than its corresponding inner diameter profile, for strength and additional stability. The middle section33bis a right circular cylinder and the uppermost section33ctapers inward. As noted elsewhere, these three outer profiles conform to the three lowermost portions27a,27b, and27cof the inner profile of air bag4. The inner profile is designed to provide maximum support for the seat as it undergoes vertical motion due to the high-performance environment in which it is placed.

Turning toFIG. 9, the lower face of the seat2includes a shaft40or similar extension for insertion into the central opening13of the pedestal (seeFIGS. 6,8, and10). For example, such a feature could be molded directly into the seat2. Surrounding shaft40is annular ridge41which fits around the outer diameter of the uppermost portion24of air bag4(seeFIG. 7). The lower face of seat2then fits against upper face26of air bag4. This arrangement keeps the seat aligned with the vertical axis despite the forces created by downward motion of the seat toward the boat (or upward motion of the boat toward the occupant of the seat) being transferred into compression of the air bag. Considering alsoFIG. 8, the length of the shaft40must be sufficient to extend substantially into the upper portion32bof pedestal12, or about eight inches beyond the lower edge of annular ridge41in the preferred embodiment. Thus, considering alsoFIG. 7, the end of shaft40extends into central opening13, occupying the space corresponding to portions27b,27cand27dof air bag4.

Returning briefly toFIG. 9, shaft40is provided with a slot or keyway feature42. This is the preferred embodiment of any feature which prevents rotation of the seat around the vertical axis. Because the lower face of the seat (at the top of shaft40and within the diameter of annular ridge41) lies against the top surface26of air bag4, rotation of the seat would introduce undesirable wear and tear on the air bag. In conjunction with slot42, to provide a smoother surface fit for the outer surface of shaft40as it travels up and down within central opening13, a mold-in sleeve50as shown inFIG. 11is added to the inner diameter of the pedestal. The mold-in sleeve50is a hollow cylinder having an inner diameter only slightly greater than the outer diameter of shaft40, and an inwardly extending mating ridge52formed into its entire height. The cross-sectional shape of the ridge52is a matter of preference—provided it is compatible with the slot42of shaft40, which typically but not necessarily means the profiles are identical—and thus in the preferred embodiment illustrated, it is rectangular. In the preferred embodiment, mold-in sleeve50is incorporated into the pedestal during rotational molding but it could be added afterward in other embodiments. Also, as illustrated, in the preferred embodiment the slot42faces forward (and thus the ridge52faces backward, or aft in the case of a nautical or aeronautical installation), but this is only a matter of choice. In the most preferred embodiment, for a radius of 4.0 inch (10.2 mm) and 0.020 inch (0.51 mm) material thickness, the channel may be 0.31 inch (7.9 mm) wide and 0.19 inch (4.8 mm) deep. (The preferred corresponding dimensions of slot42are 0.33 inch (8.4 mm) and 0.19 inch (4.8 mm), respectively, as a tight fit is desired.) A preferred height of the mold-in sleeve is 4.38 inch (11.1 mm). The preferred material is type 316 stainless steel.

Turning toFIG. 12, to improve the strength and rigidity of seat2, a flanged pedestal support plate54is molded into the seat. The uppermost plate portion55, which aligns with the underside of the seat, is preferably circular in the horizontal plane but could be other shapes. As illustrated, it has several holes56(nine are visible of the ten provided in the preferred embodiment) to reduce weight without sacrificing strength and to allow for the polymeric material that forms the seat to flow through the holes and increase the strength of the plate/seat combination. The pedestal support plate further includes a hollow cylindrical extension portion57, which extends downward into the shaft40described above.

FIG. 13illustrates a plate60which may be molded into the lowermost portion of shaft40to add strength and rigidity. Like the uppermost plate portion55of pedestal support plate54, plate60is preferably circular in the horizontal plane but could be other shapes. As illustrated, it has several large diameter holes61to reduce weight without sacrificing strength and to allow for the polymeric material that forms the seat to flow through the holes and increase the strength of the plate/shaft combination. The central hole may support a bolt lug (connected to a centered hole in the outer surface of the end of the shaft), and the four smaller holes may support studs. Plate60is preferably molded into shaft40adjacent its lowest end.

Applications

In addition to the applications noted above, specifically preferred applications are boats which are required to withstand blast, impact, and/or structural loads when they are used to blow up mines, when moving through rough seas at high speed and/or when they are hoisted aboard another structure (e.g. another vessel or a platform). Although the principles above are described and illustrated primarily with respect to boats and other watercraft, such articles are only examples. Other transportation vehicles, and the like, such as airplanes, could be considered.

Preferred Dimensions

In addition to dimensions noted above, specifically preferred dimensions for the preferred embodiment of a seat suitable for a high performance boat of the type described above include the following. Overall front-back seat length: 22.5 inch (57.2 cm). Seat width: 19 inch (48.3 cm). Seat height above deck: 18.74 inch (47.6 cm). Arm rest height above deck: 27.97 inch (71.0 cm); pivot point of arm rest height above front edge of seat: 7.25 inch (18.4 cm). Base dimensions: 14 inch (35.6 cm) square and 1.5 inch (3.8 cm) thickness; 6.0 inch (15.3 cm) hole separation, 11 inch (27.9 cm) track-to-track pitch, 1.5 inch (3.8 cm) side clearance and 1.0 inch (2.5 cm) front/back clearance measured from the centerline of each hole to the edge of the base plate. Seat shaft diameter: 4 inch (10.2 cm). Seat shaft length: 8 inch (20.3 cm). Annular ridge inner diameter: 8.25 inch (21 cm); annular ridge outer diameter: 9.75 inch (24.8 cm); annular ridge height: 1.5 inch (3.8 cm).