Cushion

Abstract

A fluid-fillable cushion comprises upper and lower layers, a first chamber and a second chamber and a discrete pressure distributing unit situated between the upper and lower layers, said pressure distributing unit providing a fluid connection between at least the first chamber and the second chamber. Such a cushion reduces leaks and allows controlled pressure equalisation between the chambers. Also disclosed is a process for making such cushions and seating products comprising such cushions.

Claims

1. A cushion comprising: an upper layer and a lower layer; at least a first chamber and a second chamber; at least one pressure distributing unit situated between the upper and lower layers, said pressure distributing unit providing a fluid connection between at least the first chamber and the second chamber, and wherein the pressure distributing unit is a discrete unit, comprising a frame and a plurality of fluid conduits, the fluid conduits comprising tubes arranged in the frame, the frame and fluid conduits being formed from the same polymer and formed as a single piece by injection moulding or extrusion, and wherein the fluid conduits are for enabling fluid to flow between the first chamber and the second chamber.

2. The cushion according to claim 1, wherein the fluid conduits are evenly spaced in the frame.

3. The cushion according to claim 1, wherein the first chamber and second chamber contain fluid, the fluid being selected from a gel, a gas, a liquid and a mixture thereof.

4. The cushion according to claim 1, wherein the plurality of fluid conduits and the frame of the pressure distributing unit each comprise a polymer independently selected from polyvinyl chloride (PVC); thermoplastic polyurethane (TPU), wherein TPU is preferably polyether TPU or polyester TPU; polyamide (PA); nylon; polyethylene terephthalate (PET); poly(ethylene-vinyl acetate) (PEVA); ethylene-vinyl acetate (EVA); and acrylonitrile butadiene styrene (ABS); and preferably polyester TPU.

5. The cushion according to claim 1, wherein the upper and lower layers comprise a polymer independently selected from polyvinyl chloride (PVC), thermoplastic polyurethane (TPU), polyamide (PA), nylon, polyethylene terephthalate (PET), poly(ethylene-vinyl acetate) (PEVA), ethylene-vinyl acetate (EVA), and acrylonitrile butadiene styrene (ABS), preferably polyether TPU or polyester TPU and more preferably polyether TPU.

6. The cushion according to claim 5, wherein the polymer of the frame of the pressure distributing unit and the polymer of the upper and lower layers are welding-compatible, preferably high frequency welding compatible.

7. The cushion according to claim 1, wherein the cushion further comprises at least one compressible pad between the upper and lower layers.

8. The cushion according to claim 7, wherein the compressible pad comprises solid foam.

9. A process for the manufacture of a cushion, the process comprising, a) providing a first layer and a second layer, b) providing a discrete pressure distributing unit comprising a frame and a plurality of fluid conduits, the fluid conduits comprising tubes arranged in the frame, the frame and fluid conduits being formed from the same polymer and formed as a single piece of injection moulding or extrusion, c) arranging the pressure distributing unit on the first layer, d) placing the second layer on the first layer and pressure distributing unit, and e) sealing the first and second layers together to form a first chamber and a second chamber with the pressure distributing unit sealed between the first chamber and the second chamber, thereby providing a fluid connection between the first and second chambers.

10. A process according to claim 9, wherein sealing is selected from adhesive bonding and welding.

11. A process according to claim 10, wherein welding is high frequency welding.

12. A process according to claim 9, further comprising b1) arranging at least one compressible pad on the first layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will now be described by way of example only, and with reference to, the accompanying drawings, in which:

(2) FIG. 1 illustrates a plan view of an embodiment of a cushion according to the present invention.

(3) FIG. 2 illustrates a plan view and side view of a pressure distributing unit as used in the present invention.

(4) FIG. 3 illustrates a plan view of another embodiment of a cushion according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows a cushion 1 of the present invention. The cushion 1 is intended to be used in the seat of a chair, and includes a coccyx cut-out region 8 to accommodate the base of the spine for user comfort and a first fluid fillable chamber 6 and a second fluid fillable chamber 7, separated by the pressure distributing unit 5. The use of two chambers 6,7 with a pressure distributing unit 5 allows distribution of fluid at an optimum and controlled rate around the cushion, generally producing an even pressure on both sides of the cushion thereby providing even support for the user. The pressure distributing unit 5 has fluid conduits 4 to allow fluid to flow between the chambers 6, 7. In the case of the cushion illustrated in FIG. 1, air is the fluid that fills the two chambers 6, 7 of the cushion 1, the pressure distributing unit 5 allowing controlled flow and generally equalisation of pressure between the two chambers 6, 7.

(6) The cushion 1 comprises a compression pad 9 of a solid open cell foam of polyurethane located between a second, lower layer 3 and first, upper layer 2 each layer 2,3 being of flexible, transparent, tough and resilient polyether thermoplastic polyurethane having a Shore hardness 90A and an ultimate tensile strength of 5400 Psi. The upper layer 2 and lower layer 3 are welded together using high frequency (radio frequency) welding along line 21 thereby forming the first and second chambers 6, 7 and the coccyx cut out 8. The pressure distributing unit 5 is sealed in position by welding.

(7) The compression pad 9 has symmetrical cut-outs 9a. In cushion 1, only the second chamber 7 is connected to air outlet 16 attached to the cut-out 9a and then by tube 14 to an air pressure release valve 10 for release pressure if required.

(8) FIG. 2 shows in more detail a top view and side view of the pressure distributing unit 5 of the present invention, including the frame 11 and the fluid conduits 4. FIG. 2 shows an example of the layout of the fluid conduits 4 in the pressure distribution unit of the present invention, in which the fluid is air and the fluid conduits 4 are six in number and evenly spaced. Of course, the number and spacing of the fluid conduits may be changed depending on intended use. The pressure distributing unit 5 is formed in one piece as a discrete unit, both the fluid conduits 4 and frame being of the same polymer, polyester thermoplastic polyurethane having a Shore hardness (D) of 68, a tensile strength (kg/cm.sup.2) of 450 and a mould shrinkage (m/m) of 0.006. The pressure distributing unit 5 may conveniently be formed by injection moulding.

(9) FIG. 3 shows an example of a sealed cushion 12 of the invention comprising a pressure distributing unit 5 with fluid conduits 4, two chambers 6, 7 and a coccyx cut-out region 8. The welding lines are again shown by a dotted line 21. In this embodiment, the fluid may be a liquid, a gel or a gas.

(10) A cushion according to the invention may be manufactured by use of adhesives or preferably by welding a first sheet/layer and second sheet/layer of a polyether thermoplastic polyurethane (having a Shore hardness 90A) together with a pressure distributing unit (formed of polyester thermoplastic polyurethane by injection moulding) situated between the layers. Generally, a first and second layer of the polyether TPU are cut into suitable shapes and the first layer is laid on to a table press of a high frequency welding machine. The welding machine is provided with suitable dies to form the first and second chambers and weld the frame of the pressure distributing unit in place. The pressure distributing unit is located on the first layer and the second layer placed over the pressure distributing unit and first layer. The table press is then closed and HF energy applied to weld the first and second layer together to form the chambers and also weld the pressure distributing unit in place. Optionally, other components of the cushion as discussed herein may be placed on the first layer, such as one or more compressible pads, and outlet/inlets for a pump (e.g. air pump) and/or pressure release valve. These optional components would then be located appropriately in the cushion after welding.