[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] It is the object of the present invention to overcome or substantially ameliorate
the abovementioned problems.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] Preferably the fire barrier material is covered by a upholstery material having good
fire retardancy characteristics (e.g. wool fabric).
[0012] 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.
[0013] 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).
[0014] The thickness of the outer skins (11 and 12) is predetermined to provide the composite
sandwich construction with greater strength where necessary.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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).
[0026] 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.
[0027] The advantages of this type of cushion construction is that it provides excellent
comfort characteristics, durability, fire retardancy, and resistance to vandalism.
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.