EP0388542A1

EP0388542A1 - An improved seat shell and cushion construction

Info

Publication number: EP0388542A1
Application number: EP89302867A
Authority: EP
Inventors: Kenneth David Wethered; Phillip John Brogan
Original assignee: KELRIT Pty Ltd trading as Spray Coatings
Current assignee: KELRIT Pty Ltd trading as Spray Coatings
Priority date: 1987-10-13
Filing date: 1989-03-22
Publication date: 1990-09-26
Also published as: AU2372688A; AU601309B2

Abstract

The present invention relates to an improved passenger seat construction for use, for example, by the transport industry, and more specifically to a seat-shell having a sandwich construction having superior strength characteristics, and to a fire resistant cushioning for passenger seats also being generally vandal resistant.

The improved seat-shell construction (10) comprises a sandwich construction using one or more formed sheets each having regularly spaced and generally parallel ribs, with outer skins (11 and 12) bonded to each side of the formed sheet.

The cushion construction (30) comprises a layer of fire barrier material (33) applied to the surface of the foamed cushion material (32) and which substantially encapsulates a flexible wire mesh 34 disposed adjacent the cushion material (32).

Description

The present invention relates to improved composite seat-shell constructions, and an improved cushion construction for seats, specifically, but not exclusively for passenger seats for use in the transport industry.
Conventional seating shells, that is, the seat cushion support structure, have to date used formed plywood, pressed steel, or a moulded solid plastic to produce a shell of sufficient strength and suitable shape for use as a transport seat.
The seat-shell is necessarily strong enough to withstand tensile and compressive forces resulting from a person sitting thereon, said forces being due to bending induced by the person between the backrest and the seat portions, or proximate the location of the mounting plate of a pedestal support or leg supporting the seat-shell.
However, previous seat-shell designs have not fully accounted for differences in tensile and compressive forces encountered between different areas of the shell. That is, the dimensions and hence the strength characteristics of the material are chosen with respect to the maximum forces encountered, and the dimensions of the material, by its nature, often do not vary between the different areas of the seat-shell. For example, a plywood shell may be designed to withstand the maximum bending moments encountered in specific zones of the shell, and the complete shell will be produced from the plywood having the necessary strength to withstand these maximum forces.
Further, the transport industry, that is, commercial and public/private transport of persons on, for example, trains, buses, aviation craft, marine craft, and other commuter vehicles, require comfortable and durable passenger seats. Vandalism is a problem that has recently become increasingly evident, and is an economic drain on the operators in the transport industry. Although previous passenger seats have been designed to be durable and fire resistant (to some extent), they have not been designed to be vandal resistant. That is, they are not able to withstand the cutting forces and penetration of sharp knives and other instruments currently used by vandals. Furthermore, previous passenger seat designs have not achieved a satisfactory level of comfort, considering known ergonomic statistics, combined with the necessary durability and fire resistance. That is, previous designs have not achieved an ergonomically comfortable, fire resistant, durable and "vandal-proof" seat construction.
It is the object of the present invention to overcome or substantially ameliorate the abovementioned problems.
In one broad form the present invention comprises a seat-shell having a construction comprising first and second outer skins, each of said skins having a predetermined thickness; and at least one layer of a formed sheet having regularly spaced and generally parallel ribs protecting transverse to the plane thereof, and which is/are positioned between said outer skins to form a composite bonded sandwich construction; said construction being formed into a predetermined shape and which has various numbers of said layers at different predetermined zones of said shape.
In a preferred form of the present invention, the sandwich construction of said seat-shell further comprises high density inserts at predetermined positions between, and being secured to said outer skins. The high density inserts are preferably positioned to provide an attachment means for mounting brackets to support said seat-shell, and to enable ancillary fixtures and trimmings to be mounted thereon.
In another preferred form of the present invention the ribs of said planar insert comprise a regular profile defining a plurality of alternate and parallel upper and lower wall sections, joined by a plurality of transverse wall sections, and wherein said upper and lower wall sections abut said first or said second outer skins or upper or lower wall sections of adjacent planar insert, and are bonded thereto.
In a further broad form the present invention provides a seat cushioning construction comprising a backing, a foamed cushion material of predetermined thickness supported thereon, and a predetermined layer of a fire barrier material applied to the external surface of said foam substantially encapsulating a flexible wire mesh disposed adjacent said surface.
Preferably the fire barrier material is covered by a upholstery material having good fire retardancy characteristics (e.g. wool fabric).
A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:

Fig. 1 is a schematic sectional view of a seat incorporating the seat-shell of the present invention;
Fig. 2 is a schematic exploded view of the seat-shell of the present invention, and a support leg, and ancillary equipment to be mounted thereto;
Fig. 3 is a schematic perspective part-sectional view of the seat-shell; and
Fig. 4 is a schematic cross-sectional view of the seat-shell.
Fig. 5 is a schematic sectional view of a seat construction incorporating the cushion construction of the present invention; and
Fig. 6 is a schematic cross-sectional view of the seat cushion construction of the present invention.

There is depicted in the drawings 1-5 a seat-shell 10 having a sandwich construction wherein a first outer skin 11, and a second outer skin 12 sandwiches at least one layer of a formed sheet 13 disposed therebetween. The outer skins are the formed planar sheet are preferably made from Fibre Reinforce Plastic (FRP).
The thickness of the outer skins (11 and 12) is predetermined to provide the composite sandwich construction with greater strength where necessary.
The sandwich construction is formed into the desired shape of a seat-shell 10, and in the zones of the shell requiring increased tensile and compressive strengths, multiple layers of the formed sheet 13 may be incorporated.
Such zones would include the transition zone between the backrest and seat portions of the shell, and between the support (e.g. pedestal leg) and the forward and rearward edges of the seat portions supported thereby. The formed sheet 13 may have a tapered "transverse" dimension to allow for a smooth transition between zones having different numbers of layers.
The formed sheet(s) 13 are bonded to the internal surfaces of the outer skins (11 and 12) or to an adjacent sheet 13 with a bonding "glue" having the characteristics of high elongation, high tear strength and fire retardancy. The sandwich construction further comprises high density foam inserts 16 provided at suitable locations such as the area(s) for mounting the seat-shell onto the supports 17, and the areas where ancillary fixtures 18 are required to be mounted thereto. In this regard, it is preferable to provide a foam insert around substantially the complete perimeter of the shell, to improve the rigidity of the complete seat-shell structure.
The formed sheet 13 is formed with a FRP material approximately 1.2 mm thick, and has a profile comprising alternate upper and lower outer walls 14 integrally joined to transverse walls 15 each connecting an alternate upper and lower outer wall 14. This construction generally resembles a sheet having a plurality of regularly space parallel ribs.
The advantages of this type of sandwich construction is that the relative compressive and tensile strengths of different zones of the formed seat-shell may be varied depending on the number of layers of formed planar inserts are incorporated. Together with the high density foam inserts 16, superior strength characteristics may be designed for specific zones of the seat-shell, and the composite structure may be lighter, stronger and more durable than known seating shells of this type.
The attached drawings 5 and 6 depict an improved cushion construction 30 comprising a plywood or press-metal backing 31, a cushion foam material 32 (e.g. closed cell sponge material) attached thereto, and a fire barrier material 33 in which is encapsulated a "vandal resistant" wire meshing 34.
The backing 31 is adapted to co-operate with and be mounted to a seat-shell 35. A separate backing 31 is provided for both the backrest and the seat section of the seat, and has curvatures consistent with that of the seat-shell 35. Further, the timber (i.e. plywood) is preferably perforated to allow "breathing" of the seat cushion construction 30.
A cushion foam 32, such as closed cell sponge, is formed in an appropriate shape for each of the backrest and seat portions, and is supported by the respective backings 31. The sponge used preferably has a compressive strength, fire retardancy and other characteristics which make it appropriate for this type of service. The foam 32 is preferably glued to the backing 31.
Applied to the exterior surface of the foam 32 is a fire resistant barrier 33 having a thickness of at least 1 mm, and preferably between 4 to 6 mm. The fire resistant barrier 33 may be of a material such as "emer-clad fire check" (a water based high solids acrylic co-polymer) or a combination of "emer-clad fire check" and a thermosetting plastic. The thickness of the barrier 33 is necessarily thick enough to encapsulate (or at least substantially encapsulate) a wire meshing 34. "Emer-clad fire check" is a material traditionally used merely as a "painted" coating or membrane, that is, having an effective thickness of approximately 0.5 mm. However, it has been found that the qualities such as flexibility, fire resistance and material structure of this material lends it for use as an effective material to encapsulate and locate the wire mesh 14 in the desired position relative to the cushion.
The wire meshing 34 is constructed from a material having a high sheer and tensile strength, so as to be generally capable of withstanding the cutting forces of sharp knives and other instruments commonly used by vandals. The wire mesh 34 is embedded into the fire resistant barrier 33. It is flexible, that is, it is designed to be generally movable in a manner consistent with the requirements of a seat upholstery. Further, the wire mesh 34 preferably has interstices between the links of the mesh 34 small enough so as to restrict penetration of sharp objects.
The mesh 34 may be produced from any suitable material (e.g. metal or plastics such as Kevlar) which provides sufficient flexibility, and suitable dimensions (i.e. must be relatively flat).
Preferably a covering 36 having good fire retardancy characteristics is used to upholster the cushion construction. The preferred material would be a 100% wool fabric.
The advantages of this type of cushion construction is that it provides excellent comfort characteristics, durability, fire retardancy, and resistance to vandalism.

Claims

1. A seat-shell 10 having a construction comprising first and second outer skins, (11,12) each of said skins (11,12) having a predetermined thickness; and at least one layer of a formed sheet (13) having a plurality of regularly spaced, transverse projections, said sheets B being positioned between said outer skins (11,12) to form a composite bonded sandwich construction; said construction being formed into a predetermined shape having various numbers of said layers at different predetermined zones of said shape.

2. The seat-shell as defined in claim 1 wherein each of said formed sheets (13) is formed from a generally rigid planar material, and said projections are defined by generally parallel ribs which project from one surface only of said sheet, and has a predetermined dimension normal to the plane thereof.

3. The seat-shell of claim 2 wherein said predetermined dimension of a second or further sheet is tapered towards at least a portion of a periphery thereof.

4. The seat-shell of claim 3 wherein said construction further comprises a mounting means for said seat-shell comprising high-density inserts (16) provided in place of said formed sheets at predetermined areas of said shape, said inserts (16) being located between and bonded to each of said outer skins (11,12).

5. The seat-shell of claim 4 wherein said predetermined areas comprise areas for mounting said seat-shell onto support members, areas for mounting ancillary fixtures to said seat-shell, and/or areas proximate the perimeter of said seat-shell.

6. The seat-shell of claims 1 to 5 wherein said outer skins and said formed sheets are made from a fibre reinforced plastics material.

7. A seal cushioning construction (30) comprising a backing (31), a foamed cushion material (32) supported thereon, a predetermined thickness of a fire barrier material (33) applied to the external surface of said foam substantially encapsulting a wire mesh (34) disposed adjacent said surface.

8. The seat cushioning construction as defined in claim 7 wherein said fire barrier material (33) is a water-based high-solid acrylic co-polymer or a mixture of said acrylic co-polymer with a thermosetting plastics material.

9. The seat cushioning construction as defined in claims 7 or 8 wherein said thickness of said fire barrier material (33) is at least 1 mm.

10. The seat cushioning construction as defined in claim 9 wherein said thickness of said fire barrier material (33) is between 4 mm and 6 mm.

11. The seat cushioning construction as defined in any one of claims 8 to 10 wherein said wire meshing generally resists cutting or tearing, and is flexible.

12. The seat cushioning construction as defined in any one of claims 7 to 11 wherein the fire barrier material (33) is covered by a fire resistant upholstery material (36).

13. A seat cushioning construction as defined in any one of claims 7 to 12 wherein said backing (31) is perforated.