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(11) | EP 0 497 615 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Spring assembly for a cushion or mattress |
| (57) A helical spring (10) for use in construction of a sprung mattress or cushion, the
spring including opposed end portions (12,14) and an intermediate connection (15)
portion, the connection portion (15) being defined by at least one coil (18) which
is substantially annular and which extends in a plane substantially perpendicular
to the longitudinal axis of the spring. |
[0001] The present invention relates to a sprung mattress or cushion and to a spring for use in constructing a mattress or cushion.
[0002] It is known to construct a core for a sprung mattress or cushion from an array of springs which are secured in side by side rows. All springs in said side by side rows are aligned in rows along both the length and width directions of the core.
[0003] In one method of construction, individual springs are encased in fabric pockets to define a string of springs. The string of springs are normally laid side by side and the fabric of adjacent strings of springs are secured to one another, say by bonding in order to give the core integrity and retain the springs in position. Adjacent springs are not directly connected to one another and so are able to compress independently of one another.
[0004] Holding the springs in an array by virtue of securing the fabric forming the pockets can be disadvantageous in that separation of the bonded fabric can occur during prolonged usage of the mattress. Once bonding has failed, the springs are no longer restrained in the length and width directions and tend to migrate in these directions resulting in failure of the mattress.
[0005] In addition, bonding of the fabric between adjacent springs tends to stiffen the mattress against flexure in lateral directions about the length of the mattress. This is undesirable in those types of mattress which require flexure in these directions.
[0006] It is a general aim of the present invention to provide a mattress or cushion core construction which overcomes or reduces the disadvantages with mattress core constructions in which adjacent pocketed springs are joined together via the fabric defining the pockets.
[0007] According to one aspect of the present invention there is provided a helical spring for use in construction of a sprung mattress or cushion, the spring including opposed end portions and an intermediate connection portion, the connection portion being defined by at least one coil which is substantially annular and which extends in a plane substantially perpendicular to the longitudinal axis of the spring.
[0008] Preferably the connection portion is defined by a single annular coil which is joined with at least one closely spaced spiral coil portion to enable the annular coil to be anchored thereto. Preferably a pair of adjacent spiral coil portions are provided symmetrically arranged either side of the plane containing the annular coil, the spiral coil portions in combination extending about substantially half of the circumference of the annular coil.
[0010] According to another aspect of the present invention there is provided a mattress or cushion including a mattress or cushion core constructed from a plurality of springs defined above, the springs being arranged in longitudinally and laterally extending rows and being connected to one another by connection means securing adjacent connection portions together.
[0011] According to another aspect of the present invention there is provided a method of constructing a mattress or cushion core including the steps of arranging a plurality of springs as defined above in longitudinally and laterally extending rows and anchoring adjacent connection portions together.
[0012] Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which :-
Figure 1 is a schematic perspective view of a barrel spring according to one embodiment of the present invention;
Figure 2 is a side view of a pair of the springs shown in Figure 1 positioned side by side for connection;
Figure 3 is a more detailed side view of the intermediate connection portion of the spring shown in Figure 1;
Figure 4 is a plan view of the intermediate portion shown in Figure 3;
Figure 5 is a schematic plan view of an array of springs connected together in accordance with one embodiment of the invention;
Figure 6 is a schematic plan view of an array of springs connected together in accordance with another embodiment of the present invention;
Figure 7 is a schematic plan view of an array of springs connected together in accordance with another embodiment of the present invention;
Figure 8 is a schematic side view of a pair of conical springs according to another embodiment of the present invention.
[0013] Referring initially to Figures 1 to 3, there is shown a barrel spring 10 for use in the construction of mattresses, cushions etc.
[0014] The barrel spring 10 is formed from a single length of spring wire 11 which is coiled to form opposite end portions 12,14 and an intermediate connection portion 15 of generally annular form.
[0015] In the embodiment illustrated in Figure 1, the intermediate portion 15 is located midway between end portions 12,14 and defines the maximum diameter of the spring 10. The intermediate portion 15 is defined by at least one coil 18 of wire which is substantially annular ie defines an annular shape. The coil 18 is orientated so as to be located in a plane substantially perpendicular to the longitudinal axis of the spring.
[0016] Accordingly, as seen in Figure 2 if springs 10 are arranged side by side, coils 18 of adjacent springs 10 lie in proximity to one another irrespective of the relative rotational position of each spring about its axis and thereby provide an anchorage coil for enabling adjacent springs to be directly joined together.
[0017] In order for spring 10 to mechanically function in a similar manner to a conventional spring, ie provide progressive resistance to applied compressive forces, it is preferable for coil 18 to be anchored to at least one adjacent coil portion.
[0018] In the embodiment illustrated in Figure 1 adjacent spiral coil portions 19,20 located either side of the coil 18 merge into coil 18 at a shallow angle and so are closely adjacent to coil 18 over a circumferential portion of coil 18. This enables coil 18 to be anchored to one or other of coil portion 19,20 by say a rigid loop or clip without causing distortion of the spring. Preferably as seen in Figures 3 and 4, the coil portions 19,20 are closely spaced or overlap with coil 18 for substantially half of the circumference of coil 18. Accordingly, when attaching two diametrically opposed clips to coil 18 at any rotational position about coil 18 at least one of the clips may also engage coil portion 19,20. If desired, coil portions 19,20 may overlap more than half of the circumference of coil 18. If connection between coil 18 and coil portions 19,20 is not required, coil portions 19,20 may extend for less than half the circumference of coil 18.
[0019] Preferably the circumferential position at which coil portion 19 merges into coil 18 is chosen to be substantially the same as that at which coil portion 20 merges into coil 18. This means that a single coil 18 can be provided using a minimum amount of wire. If desired, however, 2 or more closely spaced coils 18 may be provided for anchorage to one another.
[0020] In order to form a mattress or cushion core 25, rows 30 of springs 10 are located side by side as schematically illustrated in Figure 5. The number of springs 10 in each row 30 and the number of rows 30 and the diameter of coil 18 of spring 10 are chosen to provide the desired length and width of mattress/cushion.
[0021] Individual springs 10 are now connected together by connecting the connection portions 15 only and three alternative ways of connecting the springs together are illustrated in Figures 5 to 7.
[0022] In all 3 embodiments the mode of connection aims to achieve 3 basic criteria, viz
(i) preferably for each individual spring 10, mechanical linkage of at least one of portions 19,20 with coil 18 so as to resist axial displacement of coil 18 relative to one or other of coil portions 19,20
(ii) linkage of adjacent rows 30 so as to prevent lateral separation between rows 30, and
(iii) linkage of adjacent springs 10 in each row 30 so as to prevent separation of springs along each row 30. In the embodiment of Figure 5 each adjacent spring 10 in each row 30 is connected at its intermediate portion by connection means preferably in the form of a loop 35 which is formed from wire and is applied by a known technique by wrapping a short length of wire around the coil 18.
Accordingly within each row 30, each spring 10 is attached to a neighbouring spring 10 by two wire loops 35 which are located at diametrically opposed locations on to coil 18.[0023] As indicated by virtue of coil portions 19,20 being closely spaced to or overlapping coil 18, attachment of loops 35 at said opposed diametric positions ensures that, irrespective of the rotational position of each spring 10 about its longitudinal axis, for at least one of said positions the loop 35 also extends about coil portion 19 or 20 and so additionally connects this portion to coil 18.
[0024] Attachment of springs 10 in each row 30 by virtue of loops 35 ensures that springs 10 do not separate from one another along the row.
[0025] Adjacent rows 30 are joined together by virtue of connection means preferably in the form of loops 38 similar to loops 35 which extend about adjacent intermediate portions 15 of springs in neighbouring rows 30. Accordingly for each spring 10 (except for those in the outermost rows) two loops 38 are provided at diametrically opposed positions. Again, at least one of these loops 38 will extend about coil 18 and coil portion 19 or 20 of each spring 10.
[0026] Preferably the loops 35 and 38 are a loose fit on the intermediate portion 15 so as to ensure that the loop 35 or 38 when being applied is capable of embracing coil 18 and a coil portion 19 or 20 and after application does not tightly grip coil portion 19 or 20 to coil 18. In this way connection of coil portion 19 or 20 to coil 18 is ensured without causing distortion of the spring 10. In addition the loose connection provided by loops 35 and 38 enable articulation between connected springs and thereby enable the mattress core 25 to flex laterally in either direction about the longitudinal axis of the core 25 and also flex laterally in either direction about the width axis of the core 25.
[0028] Thus, in the embodiment of Figure 6 loops 38 are provided for connecting adjacent springs 10 in neighbouring rows 30 but adjacent springs 10 in each row 30 are not directly connected to one another due to the absence of loops 35. In order to prevent longitudinal separation of springs 10 along each row 30 an elongate cradle 40 is provided for each row 30. The cradle 40 comprises an elongate body 41 having laterally extending arms 42 at each end. The arms 42 may partially extend about the circumference of the intermediate portion 15 of the springs 10 located at the opposed ends of an associated row 30 and thereby prevent springs 10 in that row 30 separating from one another.
[0029] The elongate body 41 of each cradle 40 extends between a pair of adjacent rows 30 and is held in position by virtue of loops 38 which embrace the body 41 in addition to adjacent intermediate portions 15.
[0030] The cradle 40 is preferably formed from resilient metal wire, such as spring steel. Other materials could be used such as mild steel, wood, rigid plastic.
[0031] The loops 35 and 38 are preferably formed from a deformable metal such as steel or an alloy. In this way a relatively rigid loop or link is provided.
[0032] It is envisaged that connection means may be formed by any suitable means for attaching adjacent intermediate portions 15 together, for example ties formed from a flexible material may be used. If desired coil 18 and preferably at least one of coil portions 19 or 20 may be anchored to one another by a suitable clip or tie prior to assembly of a mattress core 25.
[0033] A further embodiment is illustrated in Figure 7 wherein both sets of loops 35 and 38 have been omitted. Instead adjacent springs 10 in each row 30 and adjacent rows 30 are joined together by virtue of elongate connection means 50 which extend inbetween adjacent rows 30. The elongate connection means 50 each comprise a helical member 51 the axis of which extends generally perpendicularly to the longitudinal axes of the springs 10.
[0034] The helical member has a diameter which is substantially constant along its length and large enough to embrace both coil 18 and either coil portion 19,20. The coils defining the helical member are spaced apart along its longitudinal axis to define an open arrangement to thereby enable them to extend about and envelope adjacent coils 18 and coil portions 19 or 20. The coils of the helical member thereby serve to prevent adjacent spring 10 in each row 30 from moving apart in the longitudinal direction of the row and also serve to prevent adjacent rows 30 moving apart.
[0035] Each helical member is preferably inserted in between each row 30 by presenting one end of the helical member to the pair of neighbouring intermediate portions 15 at one end of a pair of adjacent rows 30 and then rotating the helical member to cause its leading coil to interlace with the coils 18. By rotating the helical member its end coil is advanced to engage successive pairs of neighbouring intermediate portions 15 along the pair of adjacent rows 30.
[0036] It is envisaged that such insertion of each helical member may be achieved mechanically by a suitable machine and thereby enables a mattress core to be assembled relatively easily by an automated process.
[0037] The springs 10 in each row 30 may be individually encased in fabric pockets in a known manner to form strings of springs 10. In such a case, the connection means for securing springs 10 together are capable of piercing the fabric containing the springs.
[0038] In the embodiments illustrated with respect to Figures 1 to 7, the spring 10 is preferably shown in the form of a barrel spring. It is envisaged that the shape of the spring 10 may be different. For example, the coils between the intermediate portion 15 and the end portions 12,14 may be shaped to provide a substantially cylindrical shaped spring 10 or to provide a waisted portion between the intermediate portion 15 and end portions 12,14. These shapes of springs 10 provide independent springs capable of being secured together at a midway position by joining adjacent intermediate portions to provide a reversible mattress or cushion.
[0039] In view of the provision of the intermediate connection portion 15 adjacent springs 10 may be connected together irrespective of their rotational position.
[0040] A further embodiment is illustrated in Figure 8 in the embodiments of Figures 1 to 7, each spring 10 is a unitary member wherein the intermediate portion 15 is integrally connected with both end portions 12,14.
[0041] With the embodiment of Figure 8 it is envisaged that each spring 10 is effectively formed by two separate spring portions 70 which in the finished mattress core 25 are connected to operate in unison.
[0042] Thus in the embodiment of Figure 8, the intermediate portion 15 forms one end of a spring portion 70 and includes at least one coil 18.
[0043] To form a mattress core, two arrays of spring portions 50 are formed and adjacent intermediate portions 15 in each array are connected in a similar manner to that described in relation to Figures 5 to 7. This provides separate upper and lower arrays 61,62 of connected spring portions 70. The upper and lower arrays 61,62 are now secured together with spring portions 70 in alignment and with intermediate portions 15 of the upper and lower arrays 61,62 adjacent to one another.
[0044] Securance of the upper and lower arrays 61,62 to one another may be achieved by encasing the spring portions 70 in fabric and bonding the fabric to an intermediate layer 64. The intermediate layer 64 may be formed from any suitable flexible material such as a fabric or a foamed plastics material.
[0045] Although springs 10 have been illustrated in the drawings with adjacent springs in neighbouring rows aligned in laterally extending rows it will be appreciated that neighbouring rows may be staggered such that individual springs in one row lie inbetween adjacent springs in the neighbouring row. This is commonly referred to as a nesting formation.
1. A helical spring for use in construction of a sprung mattress or cushion, the spring
including opposed end portions and an intermediate connection portion, the connection
portion being defined by at least one coil which is substantially annular and which
extends in a plane substantially perpendicular to the longitudinal axis of the spring.
2. A helical spring according to Claim 1, wherein the connection portion is defined by
a single annular coil which is joined with at least one closely spaced spiral coil
portion to enable the annular coil to be anchored thereto.
3. A helical spring according to Claim 2, wherein a pair of adjacent spiral coil portions
are provided symmetrically arranged either side of the plane containing the annular
coil, the spiral coil portions in combination extending about substantially half of
the circumference of the annular coil.
4. A helical spring according to Claim 1,2 or 3, wherein the end portions and intermediate
portion are integrally connected.
5. A mattress or cushion including a mattress or spring core constructed from a plurality
of springs according to any one of Claims 1 to 4, the springs being arranged in longitudinally
and laterally extending rows and being connected to one another by connection means
securing adjacent connection portions together.
6. A mattress or cushion according to Claim 5, wherein the connection means comprises
loops which embrace adjacent annular coils of springs in both the longitudinally and
laterally extending rows.
7. A mattress or cushion according to Claim 5, wherein the connection means comprises
loops which embrace adjacent coils in each longitudinally extending row and elongate
cradles for preventing lateral separation of the longitudinal rows.
8. A mattress or cushion according to Claim 5, wherein the connection means comprises
an elongate helical member which extends inbetween adjacent longitudinal rows of springs.
9. A method of constructing a mattress or cushion core including the steps of arranging
a plurality of springs according to any one of Claims 1 to 4 into longitudinally and
laterally extending rows and anchoring adjacent connection portions together.