Resilient unit with different major surfaces

Abstract

A resilient unit comprises a number of wire coil springs 12, each of which is located within its own discrete pocket 14 formed by first, upper and second, lower layers 14a and 14b of material, preferably of non-woven material. The two layers 14a and 14b have been thermally, or ultrasonically, welded together at points 16 between the adjacent springs to create the pockets. The upper layer of material 14a differs from the lower layer of material 14b in respect of at least one characteristic.

Claims

1. A resilient unit suitable for providing comfort, convenience, support or protection, the unit comprising a pad having a plurality of individual coil springs of wire in an array, each spring having a spring axis and being substantially encased in an individual pocket formed between a first axially upper layer made of a first air permeable material and a second axially lower layer made of a second air permeable material, the first and second layers being joined at positions between the springs to form the pockets, wherein the first air permeable material and the second air permeable material are different materials, and wherein the first air permeable material of the first axially upper layer has a greater air permeability than the second air permeable material of the second axially lower layer such that air is allowed to circulate freely through the first axially upper layer and into spaces between the first axially upper layer and the second axially lower layer.

2. The unit according to claim 1, wherein the first and second layers of material further differ from one another in respect of at least one characteristic from a group comprising optical, thermal, tactile, structural, chemical and physical.

3. The unit according to claim 2, wherein the at least one characteristic comprises the presence, absence or degree of at least one property from a group including, waterproof, probiotic, antibacterial, antistatic, flavour, fragrance, flame-retardance, elasticity, wear resistance and permeability.

4. The unit according to claim 1, wherein the first and second layers of material further differ from one another in a thickness or a weight.

5. The unit according to claim 1, wherein the first and second layers further differ from one another in one or more defined zones on one or both layers, such that the layers have substantially identical characteristics in parts and differ in other parts.

6. The unit according to claim 1, wherein at least one of the layers comprises a composite layer made up of a plurality of sub-layers.

7. The unit according to claim 6, wherein the sub-layers are bonded or otherwise joined together.

8. The unit according to claim 1, wherein at least one of the springs have coils of different diameters at opposed ends.

9. The unit according to claim 1, wherein the first and second layers are any of bonded or welded together at spaced locations to form the pockets for the springs.

10. The unit according to claim 1, wherein, in respect of at least one of the springs, the diameter of at least one of the coils is greater than the axial length of the spring in the pocket.

11. The unit according to claim 1, wherein for at least one of the springs the first and second layers are joined together at a position that is closer to one end of the spring than the other.

12. The unit according to claim 1, wherein the first and second layers are welded together.

13. The unit according to claim 1, wherein the pockets are formed from only the first and second layers.

14. The article having at least one resilient unit according to claim 1.

15. A method of producing a resilient unit suitable for providing comfort, convenience, support or protection, the unit comprising a pad having a plurality of individual coil springs of wire in an array, each spring having a spring axis and being substantially encased in an individual pocket formed between a first axially upper layer made of a first air permeable material and a second axially lower layer made of a second air permeable material, wherein the method comprises joining the first layer and the second layer at least at locations between the springs to form a plurality of discrete pockets between the layers, wherein the first air permeable material and the second air permeable material are different materials, and wherein the first air permeable material of the first axially upper layer has a greater air permeability than the second air permeable material of the second axially lower layer such that air is allowed to circulate freely through the first axially upper layer and into spaces between the first axially upper layer and the second axially lower layer.

16. The method according to claim 15, wherein the first and second layers of material further differ from one another in respect of at least one characteristic from a group including optical, thermal, tactile, structural, chemical and physical.

17. The method according to claim 16, wherein the at least one characteristic comprises the presence, absence or degree of at least one property from a group including, waterproof, probiotic, antibacterial, antistatic, flavour, fragrance, flame-retardance, elasticity, wear resistance and permeability.

18. The method according to claim 15, wherein the first and second layers of material further differ from one another in a thickness or a weight.

19. The method according to claim 15, wherein the first and second layers further differ from one another in one or more defined zones on one or both layers, such that the layers have substantially identical characteristics in parts and differ in other parts.

20. The method according to claim 15, wherein the method comprises arranging a plurality of springs in an array.

21. The method according to claim 15, wherein, for at least one of the springs, the layers are joined together at a position that is closer to one end of the spring than the other.

22. The unit according to claim 1, wherein the first and second layers of material further differ from one another in that one of the layers is perforated and the other layer is not perforated or is perforated to a lesser degree.

23. The unit according to claim 1, wherein the first and second layers of material further differ from one another in their degree of elasticity.

24. The unit according to claim 1 wherein the second axially lower layer has a heat reflective coating.

25. The method according to claim 15, wherein one of the first layer and the second layer is perforated and the other of the first layer and the second layer is not perforated or is perforated to a lesser degree than the one of the first layer and the second layer to form the discrete pockets.

26. The method according to claim 15, wherein the first and second layers of material differ from one another in density.

27. The method according to claim 15, wherein the first and second layers further differ from one another in the presence, absence or degree of waterproofing to form the discrete pockets.

28. The method according to claim 15, wherein the first and second layers further differ from one another in their degree of elasticity to form the discrete pockets.

29. The method according to claim 15, wherein the second axially lower layer has a heat reflective coating.

30. The unit as recited in claim 1, wherein the first air permeable material of the first axially upper layer is a knitted open mesh and the second air permeable material of the second axially lower layer is a spun-bonded, non-woven material.

31. The method as recited in claim 15, wherein the first air permeable material of the first axially upper layer is a knitted open mesh and the second air permeable material of the second axially lower layer is a spun-bonded, non-woven material.

Description

(1) Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which:

(2) FIG. 1 shows, in schematic view, a portion of a resilient unit in the form of a pad, according to an embodiment of the present invention;

(3) FIG. 2 shows in schematic sectional view a portion of the pad of FIG. 1, and

(4) FIG. 3 shows in schematic sectional view a portion of a pad according to an alternative embodiment of the invention.

(5) Resilient pads for various uses, in accordance with the embodiment of the present invention described below, comprise pocketed coil springs, which are sometimes referred to as encased springs. The pad typically comprises an array of metallic coil springs individually encased in pockets formed by bonding or otherwise joining together layers of material. A convenient process for manufacturing such a panel is described in our own co-pending European patent application number EP 1 993 947.

(6) The springs are typically wider than they are tall, i.e. the diameter of at least one coil is greater than the height of the spring when in the pocket. However, in some embodiments, due to the coils at opposed ends being of different diameters and the position of the weld being closer to one end of the spring than the other, the individual springs are stable and can be at least as tall as the diameter of the largest coil, and possibly taller. The pad is stable, resilient and workable. Its plan shape can be cut to suit the desired shape of the article in which it is to be used, and because of its construction it is generally flexible, both in-plane and out-of plane.

(7) The springs can be chosen for their stiffness and size, and can be grouped into zones and combined in such a way as to provide specifically desired performance characteristics. These characteristics can be determined by the intended use of the resilient pad.

(8) An additional substrate layer may be placed on top of the pocketed springs, or below them, or in between adjacent layers of springs to improve comfort and/or performance of the pad. The additional layer preferably comprises natural materials such as hemp, cotton or wool, to assist in the recyclability of the pad.

(9) In accordance with a particularly preferred embodiment at least some of the springs have coils of different diameters at opposed ends. Such springs have a number of advantages over springs in which the coils at each end of the spring are of substantially the same diameter. Firstly, the springs can be compressed to a substantially flat configuration, with the smaller diameter coils lying within the larger diameter coils. If the springs can be compressed entirely within themselves, such that no touching of adjacent coils takes place, this also provides a much quieter panel than is the case when the coils repeatedly abut one another.

(10) Furthermore, the stiffness of a wire spring can be increased by reducing coil diameter, for a given gauge of wire. Therefore a narrower gauge spring can be made which uses less material to produce the same spring stiffness. It is necessary for the spring to have at least one coil of appropriate diameter to ensure stability within the pocket, and in particular to resist any tendency for the coil to invert within the pocket, but the other coils can be made narrower. Furthermore, a spring consisting of coils which reduce in diameter has a desirable characteristic, in that its stiffness increases progressively as it is compressed.

(11) Another, preferred feature of the invention lies in the positions where the material layers are joined, in relation to the axial height of the spring. In previously considered pocketed springs the layers of material forming the pocket were welded or otherwise bonded together either at a position half way along the axial height of the spring, or else at one end of the spring. In accordance with preferred embodiments of the present invention the joining of the layers takes place at a position closer to one end of the spring, but not at the end. More preferably, the joining takes pace closer to the end of the spring having the coil of greater diameter. The quantity of material required to cover each end of the spring may be arranged to be substantially the same.

(12) The inventors have found that this arrangement optimises stability of the spring within the pocket.

(13) Furthermore, when the force compressing the spring acts on the end of the spring with the greater diameter coil, the pocket of one spring affects neighbouring springs more significantly, and also at an earlier point in the compression, as compared with the situation in which the join is at a halfway position, for example.

(14) Turning to FIG. 1, there is shown, in schematic sectional view, generally at 10 a portion of a resilient pad according to an embodiment of the present invention. The pad comprises a number of wire coil springs 12, each of which is located within its own discrete pocket 14 formed by first, upper and second, lower layers 14a and 14b of material, preferably of non-woven material. The two layers 14a and 14b have been thermally, or ultrasonically, welded together at points 16 between the adjacent springs to create the pockets.

(15) FIG. 2 shows a portion of the pad in schematic cross-section. The upper layer of material 14a differs from the lower layer of material 14b in respect of at least one characteristic. In the example shown in the figures the upper layer is an air permeable layer, allowing air to freely circulate through the upper layer and into the spaces between the upper and lower layers. Meanwhile the lower layer 14b has a heat reflective coating on an inner, spring-facing side. This combination is well suited to a mattress or seat back, for example, in which the user's comfort is enhanced by heat retaining property of the lower reflective layer whilst air is allowed to circulate throughout the upper layer.

(16) One or both of the layers may be a composite layer, made up of a plurality of sub-layers bonded or otherwise joined together. For example, the upper layer may be a composite layer that has air permeability and is also efficient at wicking, i.e. transferring moisture away from an outer surface.

(17) The preferred method of manufacturing the pad is to bring together the upper and lower layers and to insert the partially compressed springs between the layers prior to welding or otherwise joining the upper and lower layers at edges and at positions between the springs. One example of such a method is described in our co-pending patent application referred to above.

(18) The coil springs 12 have a generally frusto-conical shape, with, in each case, the uppermost coil 12a being of the greatest diameter, and the spring tapering to its lowermost coil 12b which is of the smallest diameter.

(19) Whilst the springs shown in FIGS. 1 and 2 are of generally frusto-conical shape they could be of other shapes, such as cylindrical, hour glass or barrel shape.

(20) The use of springs which have end coils of different diameters enables the unit to be thicker—ie the height of the springs to be greater—as compared with cylindrical springs using the same quantity of material, such as wire. The pad is also free from the noise which often accompanies an array of previously considered springs.

(21) FIG. 3 shows another example of resilient unit 20 in which the first and second layers of material are different. Cylindrical springs 22 are encapsulated between an upper layer 24a of knitted open mesh having a high permeability and of a weight approximately 160 g/m2, and a lower layer 24b of spun-bonded, non-woven material of a weight approximately 50 g/m2. The open mesh of the upper layer allows air to permeate throughout the pad and is ideally suited as a user-facing side of the pad in applications such as seat bases, seat backs, mattresses and inner soles for shoes, for example.

(22) The upper layer is also more elastic than the lower layer and this has the effect of pushing the weld point 26 past a mid-point towards the lower layer. This helps to improve the stability of the pad.

(23) In what is perhaps its simplest form, the pad has first and second layers that are distinguished from one another in that one is perforated and the other is not, or one layer is perforated to a lesser degree than the other. This can result in a number of practical differences between the two layers including thermal, elastic, permeability and optical characteristics.

(24) The above examples of resilient pad have a consistent type of pocketed spring throughout. However, the pad need not have pocketed springs that are all the same. The pad can have springs that are arranged in zones, with some areas having springs with one characteristic and others having different springs, for example so that the overall pad has areas with different resilience, where this is useful.

(25) As mentioned above, seat bases and articles of flooring are only two of the possible uses of a resilient pad according to the present invention. Others include, but are not are not limited to: protective clothing or headgear, where a thin pad possibly of different zones of stiffness could be used, tables, beds and packaging.

(26) The unit may typically be in the form of a pad or panel and may be used in various applications, in particular where resilience is needed for comfort, convenience, support or protection.

(27) There are many possible combinations of first and second layers having different properties or characteristics. Examples include but are not limited to differences between the layers in respect of thermal characteristics, waterproofing, weight, density, water absorption or repellence, visual appearance, tactile properties, structural differences such as woven or non-woven, knitted, felted, resistance-to-wear characteristics, elasticity, antibacterial, anti-static, properties of flavour and/or fragrance and flame-retardance.

(28) In another example (not shown), the resilient unit uses a reflective foil on or underneath an upper layer in a mattress or cushion in order to provide warmth for a user of the mattress or cushion. For example, a zone comprising reflective foil may be located at or towards a foot-end of a mattress to help to keep the user's feet warm. Similarly, zones of greater wear-resistance may be used where the unit faces greater use or greater friction and so would otherwise be more likely to wear.

(29) Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the applicant claims protection in respect of any patentable feature or combination of features referred to herein, and/or shown in the drawings, whether or not particular emphasis has been placed thereon.