WO2011041840A1

WO2011041840A1 - Seat cushion structure

Info

Publication number: WO2011041840A1
Application number: PCT/AU2010/001318
Authority: WO
Inventors: Paul Anton Goldberg; David Levin; Nigel Justin Timothy Hobbs
Original assignee: Paul Anton Goldberg; David Levin; Nigel Justin Timothy Hobbs
Priority date: 2009-10-08
Filing date: 2010-10-07
Publication date: 2011-04-14
Also published as: AU2010305321B2; AU2010305321A1; TW201117753A

Abstract

A seat cushion structure (1) comprises a base layer (2) formed of a high resilience foam, an intermediate breather layer (3) laminated to the base layer (2) and formed of a reticulated foam and a surface layer (4) laminated to the breather layer (3) and formed of a viscoelastic foam.

Description

SEAT CUSHION STRUCTURE

Technical Field

The present invention relates to the field of seating, and in particular relates to a seat cushion structure.

Background of the Invention

Seat bases are traditionally formed utilising a homogenous foam cushion structure upholstered to a rigid base with any of various forms of fabric, leather or plastic covering. Foams of various hardness and resilience are known and utilised in an attempt to keep a desired balance between comfort and support. Laminated cushion structures have also been proposed utilising two layers of different foams, one to provide support and one to provide comfort. Such laminated forms of cushion structure may utilise viscoelastic foams, however, such foams exhibit low breathability, often resulting in a build-up of heat transferred from a person sitting on the seat. This may result in such seats feeling hot and, as a result, uncomfortable.

Typically known cushion seat structures also do not generally provide for promoting correct posture of a person sitting on the seat, promoting more of a slouched posture and poor or restricted blood circulation.

Object of the Invention

It is the object of the present invention to substantially overcome or at least ameliorate at least one of the above disadvantages, or at least to provide an alternative to current cushion seat structures.

Summary of the Invention

The present invention provides a seat cushion structure comprising:

a base layer formed of a high resilience foam;

an intermediate breather layer laminated to said base layer and formed of a reticulated foam; and

a surface layer laminated to said breather layer and formed of a viscoelastic foam.

Typically, said base layer increases in thickness towards the rear face of said cushion seat structure. Typically, the total thickness of said cushion seat structure is substantially uniform.

Typically, said intermediate breather layer has a thickness less than a thickness of each of said base layer and said surface layer throughout said cushion seat structure.

Brief Description of the Drawings

A preferred embodiment of the present invention will now be described, by way of an example only, with reference to the accompanying drawings wherein:

Figure 1 is a perspective view of a seat cushion structure; and

Figure 2 is a side elevation view of the cushion seat structure of Figure 1.

Detailed Description of the Preferred Embodiments

Referring to the accompanying drawings, a cushion seat structure comprises a lamination of three separate foam layers. The lowermost layer is a base layer 2 formed of a high resilience foam. The middle layer is an intermediate breather layer 3 laminated to the base layer 2 and formed of a reticulated foam. The upper layer is a surface layer 4 laminated to the breather layer 3 and formed of a viscoelastic foam.

The base layer 2 provides the firm supporting function of the seat cushion structure 1. The resilience of a foam is a measure of its "bounce" or "springiness", and provides an indication of its potential for shape retention. The high resilience base layer 2 thus provides the cushion seat structure with its springiness and shape retention characteristics. Resilience is tested according to Australian Standard AS2282 by dropping a steel ball onto a standard size piece of foam and measuring the distance that the ball bounces back. The height from which the ball is dropped divided by the height to which the ball bounces is defined as the resilience factor. Resilience factors of greater than 50% are understood in the industry to constitute high resilience. The high resilience foam from which the base layer 2 of the preferred embodiment is formed specifically has a resilience factor of 55%. In the preferred embodiment, the base layer 2 is formed of a polyurethane based foam, specifically formed of polyurethane foam melamine and halophosphate. A suitable specific high resilience foam is Dunlop Enduro® EN 38-200, which has a resilience factor of 55%, density of 38 kg/m³ and hardness of 200 N. The hardness is measured according to Australian Standard AS2282 as the load in Newtons required to compress a standard size piece of foam to 40% of its initial thickness. This foam also has an indentation factor, otherwise known as the "sag factor" or "comfort factor" of 2.30. This is measured according to Australian Standard AS2282 as the ratio of forces required to compress the foam to 65% and 25% of its original thickness respectively.

The surface layer 4 provides the comfort function of the seat cushion structure 1, with the viscoelastic foam from which it is formed conforming to the body of a person seated on the seat. Viscoelastic foams are characterised by very low resilience, and are otherwise known as "memory" foams. Such foams have a characteristic of slow recovery after a compression force is removed, leaving a temporary imprint of where they have been moulded to the contours of the body of a person sitting on the foam. These foams provide the support function by spreading load across a greater area and thereby reducing pressure acting on any body sitting on the foam. The viscoelastic foam of the preferred embodiment is a flexible polyurethane viscoelastic foam formed as the reaction product of toluene diisocyanate, water and polyalkoxy polyether polyol. The specific foam used in the preferred embodiment is Dunlop Viscolux LR48-90 and has a low resilience factor of 10%, relatively high density of 48 kgm³, a low hardness rating of 90 N and indentation factor of 1.94.

The intermediate breather layer 3 acts to dissipate heat buildup within the surface layer 3. Reticulated foams have a very porous structure which provides for increased breathability, allowing air to flow through the foam. This provides for increased dissipation of heat which would otherwise be trapped in the viscoelastic foam of the surface layer 4. The particular reticulated foam utilised in the preferred embodiment is Dunlop RT31 -270 which has a density of 31 kg/m³, and a hardness of 270 N.

The base layer 2, intermediate breather layer 3 and surface layer 4 are laminated utilising a water based glue according to a known lamination process.

Referring specifically to Figure 2, whilst the cushion seat structure 1 has a uniform thickness across its extent, the relative thickness of the individual layers varies. In particular, the thickness of the base layer 2 increases toward the rear face 5 of the cushion seat structure. This provides for increased support towards the rear of the seat, supporting below the rear of the buttocks of a person sitting on the seat. This tends to rotate the person's hips and back forwards to promote an improved posture, rather than have the person slouch with the hips and back rotating rearward as tends to occur when the rear portion of a uniform cushion structure collapses. This may also tend to improve blood circulation.

In the specific embodiment depicted, the base layer 2 has a thickness of 20 mm that remains constant from the front face 6 of the cushion through approximately two- thirds of its extent towards the rear face 5. The thickness of the base layer 2 then increases to a thickness of approximately 45 mm, 25 mm thicker than the front portion of the base layer 2. The lower surface of the base layer 2 is flat whilst the upper surface of the base layer 2 is concavely curved as the thickness of the base layer 2 increases towards the rear face 5. The intermediate breather layer 3 has a constant thickness of

approximately 15 mm across its extent. The surface layer 4 has a thickness of approximately 50 mm that remains constant from the front face 6 through approximately two-thirds of its extent towards the rear face 5. The thickness of the surface layer 4 decreases inversely with the thickening of the base layer 2 as it extends to the rear face 5, at which the surface layer 4 has a thickness of approximately 25 mm. The total thickness of the seat cushion structure is a constant 85 mm.

Various thicknesses of the individual layers may be utilised as desired. The base layer 2 will typically have a thickness of 10 to 30 mm toward the front face 6, whilst the surface layer 4 will typically have a thickness of 40 to 60 mm toward the front face 6. The intermediate breather layer 3 will typically have a thickness of 10 to 20 mm.

The seat cushion structure 1 may be upholstered to a rigid seat base utilising any of various fabrics, leathers or plastic coverings in the usual manner, with the base layer 2 located directly on the rigid seat base.

A person skilled in the art will appreciate various other modifications and alterations to the specific seat cushion structure described that are envisaged.

Claims

CLAIMS:

1. A seat cushion structure comprising:

a base layer formed of a high resilience foam;

2. The seat cushion structure of claim 1 , wherein said base layer increases in thickness towards the rear face of said cushion seat structure.

3. The cushion seat structure of claim 1, wherein the total thickness of said cushion seat structure is substantially uniform.

4. The cushion seat structure of claim 1, wherein said intermediate breather layer has a thickness less than a thickness of each of said base layer and said surface layer throughout said cushion seat structure.