The present invention relates to a resilient unit and to a method of manufacture of such a unit , and is concerned particularly, although not exclusively, with a resilient unit suitable for use in an upholstered article , such as a mattress , cushion, seat , pad or similar .

Pocketed springs , otherwise known as encased springs , are used in upholstered articles such as mattresses . Most pocketed spring units comprise coil springs encased individually in pockets of fabric material formed by folding over a sheet of fabric to form two leaves that envelope the springs , and then attaching the leaves together between the springs so as to form a string of springs . Figure 1 shows part of such a string 100 of springs 110 . Each spring 110 is encased in its own pocket formed by the superposed leaves of pocketing material 120 . The strings are then j oined to form an array of springs as a pocketed spring unit , as shown generally at 200 in Figure 2 . The j oining of the strings together to form an array is typically achieved either by gluing the strings together along the cylindrical surfaces of the pocketed springs , one string to the next , and so on until the unit is formed, or else by arranging the strings beside each other in the manner of an array, and then gluing sheets of fabric to the cylindrical ends of the pocketed springs , above and below, so as to form the unit .

An alternative method of forming an array of pocketed springs is described in our European Patent No . EP 1993947 . Figure 3 shows this type of unit generally at 300 , in which springs 310 are introduced between axially superposed sheets 320 of material that are then j oined at locations 330 between the springs . Such an array might be used to form a mattress core on its own or might be combined with an array of the previously described type .

Resilient units are used in many applications to provide comfort , convenience , support and/or protection .

Several types of existing resilient units , for example as are found in mattresses , are di f ficult to recycle at the end of their usable lives , either because of the method by which they were constructed or else because of the materials that were used during manufacture . Even examples which are partially recyclable are not especially attractive to recyclers from a commercial perspective either because of the costly processes needed, often because of the number of di f ferent materials used in the mattress , or else for other reasons such as the poor yield of semi-valuable components .

Embodiments of the present invention aim to provide a resilient unit , in which at least some of the aforementioned problems are addressed .

The present invention is defined in the attached independent claims , to which reference should now be made . Further, preferred features may be found in the sub-claims appended thereto .

According to one aspect of the present invention, there is provided a resilient unit comprising a body and a number of resilient elements , wherein the body comprises a block of resilient material and wherein the or each resil ient element is located within the block .

The resilient element may be located within a cavity in the block .

The body may comprise at least a first block part and a second block part , wherein the first and second block parts are arranged in use to be superposed, and preferably j oined, to form the body .

A first part of the cavity may be formed within the first block part and a second part of the cavity may be formed within the second block part . Preferably the first and second block parts are arranged to lie in superposition, more preferably so that the first and second parts of the cavity lie in registration .

The resilient element may be located partly within the first cavity part and partly within the second cavity part .

The body preferably comprises a plurality o f cavities and a plurality of resilient elements , more preferably with each resilient element located in an individual cavity .

The resilient elements may comprise springs , more preferably coil springs , for example of metal .

The block is preferably of non-woven material . More preferably, the block comprises fibrous material and may include a blend of fibres . The block material may include an elastomeric fibre , which may be a binder fibre .

The block preferably comprises recyclable material , such as polyester .

In a preferred arrangement , the first and second block parts are j oined together . Preferably, the first and second block parts are j oined together by bonding, more preferably by thermal bonding .

The cavity may include a support portion for supporting a resilient element . The support portion may be integrally formed with the block within the cavity . Where the resilient element is a coil spring, the support portion may be arranged to lie at least partly within the spring, more preferably so that one or more coils of the spring at least partly encircle the support portion .

The support portion preferably extends from a floor of the cavity . In a preferred arrangement , the cavity has a floor area, and the support portion occupies an area less than the floor area of the cavity . Alternatively, or in addition, the support portion may taper from the floor of the cavity . Where the resilient element is a coil spring having one or more substantially circular coils , the support portion may have a generally cylindrical or conical shape .

The cavity may comprise a substantially cylindrical space with block material removed . Alternatively, the cavity may comprise a substantially annular/cylindrical discontinuity, in which the block material is substantially left in place , around which the resilient element is arranged .

According to another aspect of the present invention, there is provided a method of making a resilient unit compri sing a body and a number of resilient elements , wherein the method comprises forming the body from a block of resilient material and locating the or each resilient element within the block .

The resilient element may be located in a cavity within the block .

The method may comprise forming the body from at least a first block part and a second block part , wherein the first and second block parts are superposed, and preferably j oined, to form the body . The method may include forming a first part of the cavity within the first block part and forming a second part of the cavity within the second block part . Preferably the method includes causing the first and second block parts to lie in superposition, more preferably so that the first and second parts of the cavity lie in registration .

The method may include locating the resilient element partly within the first cavity part and partly within the second cavity part .

In a preferred arrangement , method includes j oining the first and second block parts together, preferably by bonding, more preferably by thermal bonding . The method may comprise removing material from the block to form the cavities . The method may comprise removing material from the block by a router process .

Alternatively, the method may comprise cutting the block using a substantially hollow cylindrical cutting tube . A substantially annular/cylindrical cut/discontinuity may be cut into the block, in which the block material is substantially left in place with the resilient element around it .

Preferably the method includes supporting the resilient element on the tube , optionally magnetically, which tube has a substantially circular cutting edge . The method may include cutting into the block and withdrawing the cutter tube leaving the resilient element behind in the block .

In a further aspect , the invention provides a computer programme product on a computer readable medium, comprising instructions that , when executed by a computer, cause the computer to perform a method according to any statement herein .

The invention also comprises a program for causing a device to perform a method according to any statement herein .

The invention may include any combination of the features or limitations referred to herein, except such a combination of features as are mutually exclus ive , or mutually inconsistent . A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings , in which :

Figure 1 shows schematically a previously considered string of springs ;

Figure 2 shows schematically a resil ient unit made up of a plurality of the springs of Figure 1 ;

Figure 3 shows schematically an alternative type of resilient unit according to the prior art ;

Figure 4 is a schematic end view of a first embodiment of resilient unit according to the present invention;

Figure 5 is a schematic sectional view of the unit of Figure 4 ;

Figure 6 is a schematic sectional view of a second embodiment of resilient unit according to the present invention;

Figure 7 is a schematic exploded view of part of a third embodiment of resilient unit according to the present invention;

Figure 8 shows schematically a further embodiment of unit according to the present invention;

Figure 9 shows schematically a still further embodiment of unit according to the present invention; Figure 10 shows schematically a further yet embodiment of unit according to the present invention; And

Figures l la- l ld show schematically another method and apparatus for introducing a spring into a block .

Turning to Figure 4 , this shows , generally at 1000 a resilient unit according to a first embodiment of the present invention . The resilient unit 1000 is shown in schematic end view and comprises a cuboidal block body 1100 made up of first and second block parts 1110 and 1120 which are superposed and j oined together . Defined within the parts 1110 and 1120 , and shown in broken lines , are substantially cylindrical cavities 1210 and 1220 respectively which lie in registration to form continuous spaces in which are placed resilient elements in the form of coil springs 1300 , also shown in broken lines . The drawing shows five pairs of cavities and five springs . In reality, the cavities , with springs inside them, comprise an array extending substantially the length and width of the body 1100 . The cavities and springs are substantially enclosed within the body and ordinarily not visible from the outside . The dimensions of the body, and the number and si ze of the springs and their cavities , may be selected according to requirements ( e . g . for a mattress , seat base etc ) .

The springs 1300 are coil springs of steel and the block parts 1110 and 1120 are formed recyclable material , in particular from blended fibres , including polyester fibres . The cavities 1210 and 1220 are created by removing material from the blocks , for example by a router tool . Figure 5 is a schematic cross-sectional view in which a row of the cavities 1210 and 1220 are exposed and the springs 1300 shown .

The blocks 1100 are themselves resilient and deform under load, for example when a user (not shown) sits or lies on the unit . The combination of springs and blocks provides a comfortable resilient characteristic .

Figure 6 is a schematic sectional view of a second embodiment of resilient unit which is identical to that shown in Figure 5 except for the addition of further structure within the cavities . In particular, at a lower portion of the cavity 1220 , extending upwardly from a floor thereof , is a support seat 1400 for the spring 1300 . The support 1400 is integrally formed from the block part 1120 and is generally cylindrical in shape . It is dimensioned to receive a part of the spring 1300 so that one or more turns of the spring wrap around the support which holds the spring in position .

Figure 7 is an exploded schematic view of a third embodiment of resilient unit according to the present invention . Corresponding parts have been accorded the same reference numerals as in the previous figures . The drawing shows the upper block part 1110 and lower block part 1120 separated to reveal the respective cavities 1210 and 1220 and also the springs 1300 . However, in this example , the support seat 1400 inside the lower cavity 1220 is of a f rusto-conical shape and is shown in broken lines . To create the resil ient unit according to the examples shown, two blocks 1110 and 1120 are taken (which may be derived from a common block) . Arrays of cavities 1210 and 1220 are made , for example using a router tool (not shown) in the respective block parts . I f desired, the cavities may include a support seat 1400 , which may be created as part of the routering process .

The cavities in the upper and lower block parts are created so that they will lie in registration when the block parts are brought together . The springs 1300 are inserted in the lower cavities and then the block parts are brought together and j oined . The block parts may be j oined together using a thermal sealing process , for example by passing a heated element over one or both of the j oining surfaces of the blocks .

The thus- formed unit can be used in a variety of articles , including upholstered articles such as mattresses , cushions , pads and seats , for example . The resilient characteristics may be tailored to suit the intended use . For example , the number and si ze of the springs 1300 may be selected and the shape and si ze of any support seat 1400 may be chosen accordingly . Since the body itsel f contributes to the resilient character of the unit as a whole , it may be possible to use springs of a shorter length as there is no need for the springs to be held under compression within the pockets .

The cavities are preferably created so as to be slightly smaller than the springs , in diameter and/or length, so that the springs are held by friction in their cavities by the block material , which is beneficial during assembly .

The material removed to create the cavities may be re-used and the unit as a whole is completely recyclable due both to its constituent materials and also its simple structure .

Figures 8- 10 illustrate some examples of alternative structures , all of which are in accordance with the present invention .

Figure 8 shows an alternative embodiment in which a s ingle cavity 1200 lies substantially entirely within one block part 1120 and the other block part 1110 acts as a closure for the cavities .

Figure 9 shows an alternative embodiment in which the body is made up of a single block 1100 , with the resilient elements being located entirely within cavities 1200 formed in the single block . In this embodiment , the cavities are ef fectively through-holes in the block which usefully promote ventilation in the body . The springs 1300 are held by friction in position in the cavities , as the cavities are dimensioned to be slightly smaller than the diameters of the springs . Instead of being wholly within the block, the springs 1300 may protrude therefrom, either on an upper edge of the block, a lower edge or from both edges .

Figure 10 shows another alternative embodiment , in which the body is made up of more than two blocks . In this embodiment , there are two blocks 1110 and 1120 , each with cavities , respectively 1210 and 1220 retaining springs 1300 . Sandwiched between the blocks 1110 and 1120 is a third block 1130 . In this embodiment this third block has no cavities and no springs . It may be used to contribute to a sti f fer body characteristic .

Figures l la- l lc show schematically a method of inserting a spring 2300 into a block 2100 . A rotatable cutter tool 2500 comprises a cylindrical spring support 2510 onto which is placed a spring 2300 , the axial length of which is slightly greater than the support 2510 . The support 2510 is magnetic and the spring is held in place on the support by magnetism . The support 2510 comprises a substantially hollow metal tube , the leading edge of which 2510a comprises a sharp cutting edge .

As the rotating tube 2510 advances towards the block 2100 , it begins to make an annular/cylindrical cut/discontinuity in the material of the block for the spring 2300 to occupy . Once the cut is suf ficiently deep to accommodate the spring, the cutter/ support is withdrawn, leaving the spring inside the block where it is lightly gripped due to the diameter of the spring being slightly greater than the cut made by the cutter .

Note that substantially no block material i s removed by the cutting . Rather, the block material is parted or displaced by the cutting edge , leaving behind a cylindrical-shaped discontinuity for the spring . Leaving the block material in place is beneficial because it avoids wasting material and also the material left in place can contribute to the resilience of the unit and optionally act as a damper for the action of the spring .

In Figure 11b the spring is ful ly inserted, stopping short from the opposite side of the block .

In Figure 11c the tool has been withdrawn leaving the spring inside the block . A cover layer 2110 , optionally of the same material as the main block, has been placed over the spring, and secured in place optionally by heat sealing . I f any block material is lying proud of the block surface after insertion of the springs , it can be flattened by e . g . , a roller (not shown) prior to adding the cover layer . 2110 .

In these drawings a single spring is shown . However, it will be understood that the finished block will typically include an array of springs , which may be inserted using the abovedescribed method either singly or simultaneously in rows or other patterns or complete 2-dimensional arrays .

Figure l id shows part of the cutter tool 2500 in more detail , including the hollow magnetic spring support 2510 and the circular cutting edge 2510a .

In other implementations (not shown) , further combinations of blocks and springs may be employed to create a resilient unit with the desired characteristics .

Optionally the body may be at least partly encased in a cover or sheet (not shown) . Whereas the material used for the blocks in the above examples is a blend of fibres including polyester, it wil l be understood by the skilled person that the material ( s ) of the blocks may include one or more of (but not limited to ) : other fibres , foams , including polyurethane foams , latex and other synthetic and natural materials .

Whilst endeavouring in the foregoing speci fication 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 .