A MATTRESS SPRING CORE COMPRISING AT LEAST ONE CORNER SPRING POCKET FOR INCREASING MATTRESS SHAPE STABILITY

Abstract

A mattress spring core including a plurality of spring pockets arranged in longitudinal columns and transverse rows, wherein at least one corner spring pocket projects longitudinally from an adjacent column end spring pocket.

Claims

1. A mattress spring core comprising a plurality of spring pockets arranged in longitudinal columns and transverse rows, wherein at least one corner spring pocket projects longitudinally from an adjacent column end spring pocket.

2. The mattress spring core according to claim 1, wherein the spring pockets are arranged in a plurality of parallel central spring strings forming a rectangular central part, and in at least two outermost spring strings arranged on opposite sides of the central spring strings, wherein at least one of the outermost spring strings is longitudinally displaced relative the central spring strings.

3. The mattress spring core according to claim 2, wherein a width (W.sub.SP) of the spring pockets of the outermost spring string is smaller or greater than the width (W.sub.SP) of the spring pockets in a central spring string.

4. The mattress spring core according to claim 2, wherein the spring strings are attached to each other side by side by means of an adhesive, preferably a hot melt adhesive, or by ultra-sonic welding.

5. The mattress spring core according to claim 2, wherein the spring pockets of each central spring strings are aligned centre-to-centre with the spring pockets of each adjacent central spring string.

6. The mattress spring core according to claim 2, wherein the central spring strings comprises fewer spring pockets than the outermost spring strings, preferably each of said central spring strings comprises one spring pocket less than each of the outermost spring strings.

7. The mattress spring core according to claim 2, wherein the spring pockets of each outermost spring string are aligned off centre with the spring pockets of each adjacent central spring string.

8. The mattress spring core according to claim 1, wherein the corner spring pockets project longitudinally by at least one third of a spring pocket width (W.sub.SP).

9. The mattress spring core according to claim 1, wherein the plurality of spring pockets have the same width (W.sub.SP).

10. The mattress spring core according to claim 1, comprising four corner spring pockets, each projecting longitudinally from an adjacent column end spring pocket.

11. The mattress spring core according to claim 1, comprising eight corner spring pockets arranged in pairs, each pair of corner spring pockets projecting longitudinally from an adjacent column end spring pocket.

12. The mattress spring core according to claim 1, comprising one or more layers of spring pockets.

13. The mattress spring core according to claim 1, wherein a fabric material of the spring pocket is a nonwoven fabric material comprising thermoplastic material.

14. The mattress spring core according to claim 1, wherein a spring constant of the spring of the corner spring pocket is higher than a spring constant of the spring of the adjacent column end spring pocket.

15. A mattress comprising the mattress spring core according to claim 1, and a mattress cover enclosing said mattress spring core.

16. A method for manufacturing a mattress spring core comprising steps of: providing a plurality of spring pockets arranged in longitudinal columns and transverse rows, and arranging at least one corner spring pocket such that it projects longitudinally from an adjacent column end spring pocket.

17. The mattress spring core according to claim 8, wherein the corner spring pockets project longitudinally by half of the spring pocket width (W.sub.SP).

18. The mattress spring core according to claim 12, comprising two layers of the spring pockets.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be described further below by way of example and with reference to the enclosed drawings. In the drawings:

[0028] FIG. 1a is a top view of the mattress spring core according to one embodiment;

[0029] FIG. 1b is a top view of a mattress spring core according to another embodiment;

[0030] FIG. 2 is an enlarged portion of a portion of a spring string comprised in said mattress spring core;

[0031] FIG. 3 is a cross-sectional view of a plurality of spring pockets of a spring string;

[0032] FIG. 4 is a perspective view of a mattress, including a mattress spring core according to one embodiment; and

[0033] FIG. 5 is a flowchart showing a method of producing a mattress spring pocket.

DETAILED DESCRIPTION OF EMBODIMENTS

[0034] In the following a mattress spring core will be described, as well as a mattress having such mattress spring core, and a method for producing the mattress spring core. As used in this description the expression longitudinal refers to the direction of the length of the mattress, i.e. the normal feet-to-head direction of a person lying on the mattress comprising the mattress spring core. The expression transverse refers to the direction of the width of the mattress spring core. The longitudinal and transverse directions are consequently perpendicular to each other.

[0035] Preferably, the mattress spring core has a substantially rectangular form as seen from above (shown in FIGS. 1a-b and 4). Thus, the length of the mattress spring core corresponds to the longer sides of the rectangle and the width of the mattress spring core corresponds to the shorter sides of the rectangle. It is for instance common to have mattresses with a length of 200 cm and a width of 90 cm, as one example only. The terms upper and lower are used to define the normal position of the mattress, i.e. having an upper side onto which the person using the mattress is intended to rest upon, and a lower side forming the underside of the mattress during normal use.

[0036] FIG. 1a shows a mattress spring core 1 as seen from above. The mattress spring core 1 comprises a plurality of spring pockets 8 arranged in longitudinal columns and transverse rows. The spring pockets 8 are preferably distributed in a plurality of longitudinally extending spring strings 3, 4.

[0037] The spring strings 3,4 are arranged side by side, which together form the mattress spring core 1. The spring strings 3,4 are central spring strings 3 or outermost spring strings 4. The two outermost spring strings 4 are arranged along the outer longitudinal edge of the mattress spring core 1, on an external side of the last central spring strings 3. The outermost spring strings 4 are in direct contact, or immediately next to, the central spring strings 3.

[0038] As can be seen in FIG. 1b, another embodiment of a mattress spring core 1 is shown where two outermost spring strings 4 are arranged on each side of the central spring strings 3. Also in this embodiment the inner ones of the outermost spring strings 4 are in direct contact, or immediately next to, the central spring strings 3.

[0039] Referring to both FIG. 1a and FIG. 1b, each spring string 3,4 comprises a fabric material 6 forming pockets or cavities configured to hold springs 7 (see FIG. 3). Hence, a spring pocket 8 comprises a spring 7 and a fabric material 6 enclosing the spring 7. The fabric material 6 may e.g. be a nonwoven fabric material, preferably a material comprising thermoplastic material or another material which is suitable for ultrasonic welding or friction welding. The springs 7 are preferably coil springs (as shown in FIG. 3), but other spring types are also conceivable.

[0040] In the embodiment of FIG. 1a the mattress spring core 1 comprises four corner spring pockets 8. In the embodiment of FIG. 1b the mattress spring core 1 comprises eight corner spring pockets 8.

[0041] These corner spring pockets 8 are the end spring pockets of the outermost spring strings 4. The last central spring strings 3 have end spring pockets 8, arranged adjacent to the corner spring pockets 8. As will be explained further in the following, the corner spring pockets 8 project longitudinally relative the adjacent end spring pockets 8.

[0042] With reference to FIG. 2, an enlarged portion of a spring string 3,4 is shown. The spring pockets 8 are made from the fabric material 6, and are separated from each other by a welded edge seam 10, formed when manufacturing the spring pockets 8. The portion of the spring string 2 in FIG. 2 comprises two spring pockets 8, each having a diameter or width W.sub.SP.

[0043] As shown in FIG. 1a and FIG. 1b each central spring string 3 is arranged as an array of spring pockets 8, where the central spring strings 3 are aligned in both the transversal and the longitudinal direction such that adjacent spring pockets 8 are aligned centre-to-centre. Together, the central spring springs 3 are connected to each other form a central part 30 of the mattress spring core 1. The central part 30 has a rectangular shape. However, in other embodiments of the disclosed mattress spring core 1, the central part 30 may have a square or more elongate shape than shown in FIG. 1a and FIG. 1b.

[0044] As opposed to the central spring strings 3, the outermost spring strings 4 are not centre-to-centre aligned with respect to the central spring strings 3. This achieves protruding corners on the mattress spring core 1 by means of the corner spring pockets 8.

[0045] The outermost spring strings 4 in FIG. 1a and FIG. 1b are all arranged offset in the longitudinal direction with respect to the central spring strings 3. The displacement of the outermost spring strings 4 is about half a spring pocket 8, i.e. half a width W.sub.SP of the spring pocket 8. Therefore, as shown in FIG. 1a and FIG. 1b, each corner spring pocket 8 project by approximately a half spring pocket width W.sub.SP from the short, or longitudinal end of the central part 30 of the mattress spring core 1. Hence, the outer spring strings 4 comprise one additional spring pocket 8 compared to the central spring strings 3.

[0046] The arrangement of the outer spring strings 4 as described above creates additional material at the corners and thus minimizes the space which otherwise may exist between the corners of the mattress spring core 1 and an internal corners of a mattress cover. Therefore, the problem of collapsing mattress corners is mitigated and prevented. A size and shape stable mattress spring core 1 is achieved by the addition of one extra half spring in each corner of the mattress spring core 1.

[0047] Furthermore, the concept of using longer and offset outermost spring strings 4 as disclosed herein enables an automated production, since the outermost spring strings 4 may be manufactured in the same way and by the same materials as the central spring strings 3.

[0048] Moreover, the mattress spring core 1 disclosed herein provides a more sustainable solution against collapsing mattress corners, since less and/or more sustainable materials are used compared to the use of a supporting metal rail or the use of stuffed polyurethane foam glued to the spring coil, which are common methods used in the art today.

[0049] In addition, the solution presented herein provides a less labour intense manufacturing process, since the solution enables a lean and automated production. The mattress spring core 1 comprising the outermost spring strings 4 with corner edge spring pockets 8 is formed directly during the production of the mattress spring core 1 as such.

[0050] Further, the mattress spring core 1 may be produced with varying sizes since the reinforcement for the mattress corners merely comprises displacement of the outermost spring strings 4 in relation to the central spring strings 3. A metal rail frame embedding the edges of a mattress spring core, on the other hand, would need to be manufactured specifically for each mattress size.

[0051] A further effect of the mattress spring core 1 as disclosed herein, is that the mattress spring core 1, and later a mattress 20 (see FIG. 4) comprising the mattress spring core 1, can be packed by vacuum pressing and roll-up for space savings and easier transports.

[0052] Also, the stiffness and/or softness and zones of different stiffness/softness of the mattress spring core 1 can easily be adjusted during the manufacturing process since the resilience of the springs 7 within a central or outermost spring string 3, 4 may be altered during manufacturing, or the resilience of the strings 7 in the central spring strings 3 and the outermost spring strings 4 can be different. Alternatively, the central part 30 is formed by central spring strings 3 having springs 7 of various resilience. Optionally, the diameter of the spring pockets 8 may vary between the outermost spring strings 4 and the central spring strings 3, such that the width W.sub.SP of the spring pockets 8 of the central spring strings 3 is smaller than the width W.sub.SP of the spring pockets 8 of the outermost spring strings 4, or such that the width W.sub.SP of the spring pockets 8 of the outermost spring strings 4 is smaller than the width W.sub.SP of the spring pockets 8 of the central spring strings 3.

[0053] In FIG. 1a and FIG. 1b, a spring string 3,4 forms one column of the mattress spring core 1. The spring strings 3,4 have a longitudinal extension along the length of the mattress spring core 1. In other embodiments, the spring strings 3,4 may be arranged in a transverse direction, extending along the short or longitudinal sides of the mattress spring core 1.

[0054] The spring strings 3,4 may be attached to each other by means of an adhesive, such as a hot melt adhesive, by sewing, or by stapling. Other adhesives are also feasible, as well as other feasible fastening techniques known in the art.

[0055] Further, the spring constant of the springs 7 may vary and the mattress spring core 1 may comprise reference springs and stiffer springs compared to reference springs comprised in the mattress spring core 1. For instance, the stiffer springs have a spring constant in the range of 15% to 30%, more specifically 20% to 25%, and preferably approximately 25% higher than the reference springs. In addition, the diameter of the springs 7 can be of varying size.

[0056] An increased spring constant can be achieved for instance by increasing the wire gauge of the springs 7. An exemplary diameter for stiffer frame springs may be approximately 1.9 mm whilst reference springs may have a diameter of approximately 1.7 mm.

[0057] Alternatively, an increase in spring constant of the springs 7 could be achieved by removing one convolution on each of the springs 7. The exact use of stiffer springs can of course be varied; in one embodiment each of the outermost spring strings 4 comprises stiffer springs 7 than the central spring strings 3. Optionally, the corner spring pockets 8 are enclosing stiffer springs 7 than the remaining spring pockets 8 of the mattress spring core 1.

[0058] In FIG. 1a and FIG. 1b, the mattress spring core 1 is comprised of a monolayer of spring strings 3,4. It is to be realized that combinations of several layers of spring strings 3,4, such as two, three or four layers, are also feasible to form a mattress spring core 1. In such case, additional combinations of springs 7 having varying stiffness and/or diameter is possible. For instance, when combining two layers of spring strings 2, three outermost rows can be made of stiffer frame springs in the upper and/or the lower layer along the longitudinal edges of the mattress spring core 1 and two outermost rows of stiffer frame springs in the upper and/or the lower layer along the transversal edges.

[0059] Each spring string 3,4 may comprise between 8 and 30, such as between 12 and 16 spring pockets 8 per meter. In one particular embodiment each spring string 3, 4 comprises 25 spring pockets 8 per two meters, i.e. 12.5 spring pockets 8 per meter. A mattress spring core 1 of a typical length of 200 cm may for example comprise between 16 and 60, preferably between 20 and 32 spring pockets 8 in the longitudinal direction. Hence, if the spring strings 2 are arranged in a transverse direction, along the short edge of the mattress spring core 1, each spring string 3,4 comprises fewer spring pockets 8 than when the spring strings 3,4 are arranged along the length of the mattress spring core 1.

[0060] Each spring string 3,4 is attached by means of an adhesive, preferably hot melt adhesive, side by side to another spring string 3,4. Between 10 to 25 spring strings 3,4, preferably approximately 13 to 15 spring strings 3,4 (as shown in FIG. 1a) together form a mattress spring core 1 with a width of 90 cm. However, fewer or more spring strings 3,4 may be used to decrease or increase the width of the mattress spring core 1, or to decrease or increase the length of the mattress spring core 1 if the spring strings 3,4 are arranged along the width of the mattress spring core 1 (as opposed to the extension direction of the spring strings 3,4 shown in FIG. 1a and FIG. 1b).

[0061] In FIG. 3 a cross-sectional view taken from the side of a part of a mattress spring core 1 is shown. The mattress spring core 1 has a number of spring pockets 8 enclosing respective springs 7. Although shown as barrel-shaped, the springs 7 may have other configurations. The mattress spring core 1 further has a foam cover 11 arranged on top of the spring pockets 8. The foam cover 11 further stabilizes the rectangular shape of the mattress spring core 1. While many different materials and dimensions for the foam cover 11 may be considered, in one embodiment the foam cover 11 is made of polyurethane foam at a density of 20-30 kg/m3. The thickness of the foam cover 11 may be in the range of 1-25 cm, such as in the range of 3-10 cm.

[0062] Now turning to FIG. 4, a mattress 20 is shown. The mattress 20 comprises a mattress spring core 1, a foam cover 11, and a mattress cover 22. The mattress cover 22 may e.g. comprise waddings, linings, and tickings, as is well known in the art. Preferably, the mattress cover 22 is robust enough to maintain the size and shape of the mattress spring core 1. It should be noted that the foam cover 11, as well has the mattress cover 22, has been cropped. For a final mattress 20, the foam cover 11 and the mattress cover 22 will cover the entire mattress spring core 1. As has been explained above, the protruding corner spring pockets 8 of the mattress spring core 1 will fill the interior corners of the mattress cover 22 such that the entire mattress 20 will exhibit a rectangular shape with well-defined corners. For the sake of completeness, also the adjacent end spring pockets 8 are indicated in FIG. 4.

[0063] A method 100 for manufacturing a mattress spring core 1 is schematically shown in FIG. 5. The method 100 may comprise a step 102 of providing a plurality of spring pockets 8 arranged in longitudinal columns and transverse rows, and a step 204 of arranging at least one corner spring pocket 8 such that it projects longitudinally from an adjacent column end spring pocket 8. The method 100 may further comprise an additional step 106 of arranging the mattress spring core 1 in a mattress cover 22, thereby extending the scope of the method 100 to actually produce a mattress 20.

[0064] The spring strings 3, 4 (both the central spring strings 3 and the outermost spring strings 4) may be manufactured according to the following. Each spring 7 is manufactured from a metal wire. Each spring 7 is positioned in a spring pocket 8 made of a fabric material 6 whereafter the spring pockets 8 are sealed, preferably by means of welding.

[0065] If the mattress spring core 1 comprises double layers of spring strings simultaneous manufacturing of the springs 7 for an upper layer and a lower layer may be performed, while enabling the alternation of two separate wires with different characteristics for each of the layers of the spring string 3, 4. Each spring string 3,4 can be varied in a large number of ways. For instance, stiffer springs may be placed in the upper layer, the lower layer or in both layers.

[0066] To form the mattress spring core 1 the spring strings 3, 4 are preferably cut when a sufficient number of spring pockets 8 are formed, for instance around 25 spring pockets 8 for a typical mattress length of 200 cm.

[0067] Further, each spring string 3,4 is attached side by side to another spring string 3, 4 by means of an adhesive, such as a hot melt adhesive.

[0068] It is also to be realized that the spring pockets 8 may be partially or completely formed before and/or after the springs 7 are positioned therein. A spring pocket 8 is usually formed by folding an elongate piece of fabric material 6 along its length, and welding the folded fabric material 6 to form a tube. A plurality of springs 7 are arranged within the tube, and welds are provided between the springs. The welding is performed orthogonally with respect to the longitudinal length of the folded fabric material, such that a plurality of connected spring pockets 8 are formed.

[0069] Again referring to FIG. 5, the method 100 may be performed by an additional step 108 in which the mattress 20 is vacuum packed and optionally rolled up and wrapped such that a very compact and space-reducing packaging is obtained. Once unpacked, the mattress 20 will return to its desired and planar shape while corner spring pockets 8 ensures the rectangular shape of the mattress. Optionally, step 108 may be performed directly on the mattress spring core 1. In such embodiment the advantages of the corner spring pockets 8 are even more evident, as there is no ticking or other additional layers or foam cover to assist in maintaining the desired rectangular shape of the mattress spring core 1.

[0070] The present disclosure thus presents a mattress spring core 1 comprising a plurality of spring pockets 8 arranged in longitudinal columns and transverse rows by a plurality of parallel central spring strings of the same length and forming a rectangular central part, and by at least two outermost spring strings arranged on opposite sides of and immediately next to the central spring strings. At least one corner spring pocket 8 projects longitudinally from an adjacent column end spring pocket 8.

[0071] It should be mentioned that the inventive concept is by no means limited to the embodiments described herein, and several modifications are feasible without departing from the scope of the appended claims. In the claims, the term comprises/comprising does not exclude the presence of other elements or steps. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. The terms a, an, first, second etc. do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.