HIGH TENSION COIL SPRING STRUCTURE FOR BED MATTRESS HAVING MEANS FOR PREVENTING FRICTION NOISE

Abstract

A high tension coil spring structure for a bed mattress includes spring bodies and exposed wiring portions which absorb an external load. Diameter-increasing portions (A) are formed on at least one of upper and/or lower end wiring portions (14, 14′) of body wiring portions (12), and provide spaces in which upper and/or lower exposure start wiring portions (16-5, 16-5′) move upward and downward. Rigid support ends (18) are formed on at least one of the body wiring portions (12) and upper and lower exposed wiring portions (16, 16′), and absorb a compressive load. The diameter-increasing portions and the rigid ends of the coil spring structure fundamentally prevent noise caused by friction between the exposed wiring portions and surrounding wiring portions when the exposed wiring portions are compressed and significantly increase the elasticity of the exposed wiring portions.

Claims

1.-17. (canceled)

18. A high tension coil spring structure for a bed mattress comprising: body wiring portions (12) which are disposed regularly at preset distances from each other in the space between an upper edge member (20) and a lower edge member (20′), upper and lower end wiring portions (14, 14′) which are provided on both ends of the body wiring portions (12) and set within the range in which the upper and lower edge members (20, 20′) are disposed; upper exposed wiring portions (16) which extend from the upper end wiring portions (14) so as to be exposed from the upper edge members (20); diameter-increasing portions (A) which are provided on the upper end wiring portions (14) and define spaces in which upper exposure start wiring portions (16-5) of the upper exposed wiring portions (16) move upward and downward while the coil spring structure is being compressed; and means for preventing friction noise which are provided on the upper end wiring portions (14), wherein the means for preventing friction noise include rigid support ends (18) which are provided on at least one of the body wiring portion (12) and the upper exposed wiring portions (16), and absorb shock by absorbing a compressive load applied from the upper exposed wiring portions (16), and the diameter-increasing portions (A) provide spaces in which upper exposure start wiring portions (16-5) move upward and/or downward while the coil spring structure is being compressed, thereby preventing frictional noise between the upper end wiring portions (14) and the upper exposure start wiring portions (16-5), and when a compressive load is applied to the coil spring structure, a plurality of wiring portions formed in the upper exposed wiring portions (16) move upward and downward along the side walls of the rigid support ends (18), thereby significantly increasing elasticity, wherein linear free ends (B) are provided on coil ends of the lower end wiring portions (14′), and are opened without being engaged with wiring portions.

19. The high tension coil spring structure according to claim 18, wherein at least one of the upper and lower end wiring portions (14, 14′) has a shape of a round coil spring, and/or wherein at least one of the upper and lower end wiring portions (14, 14′) has a shape of an offset coil spring, and/or wherein at least one of the upper and lower end wiring portions (14, 14′) has a shape of a round offset coil spring.

20. The high tension coil spring structure according to claim 18, wherein one or two concave portions are provided on at least one of the upper end wiring portions (14) and the lower end wiring portions (14′), the concave portions increasing an inner diameter of the at least one of the upper end wiring portions (14) and the lower end wiring portions (14′).

21. The high tension coil spring structure according to claim 18, wherein the diameter-increasing portions (A) comprise predetermined portions of the upper end wiring portions (14) and/or the lower end wiring portions (14′) which increase an inner diameter of the upper and/or lower end wiring portions (14, 14′) to be greater than an outer diameter of the upper exposure start wiring portions (16-5) when the rigid support ends (18) are formed on the body wiring portions (12).

22. The high tension coil spring structure according to claim 18, wherein the diameter-increasing portions (A) comprise predetermined portions of the upper end wiring portions (14) and/or the lower end wiring portions (14′) which increase an inner diameter of the upper and/or lower end wiring portions (14, 14′) to be greater than an outer diameter of the body wiring portions (12) when the rigid support ends (18) are formed on the upper exposed wiring portions (16).

23. The high tension coil spring structure according to claim 18, wherein the diameter-increasing portions (A) have a shape of a round spring.

24. The high tension coil spring structure according to claim 18, wherein the diameter-increasing portions (A) have a shape corresponding to a shape of the upper and lower end wiring portions (14, 14′).

25. The high tension coil spring structure according to claim 18, wherein linear free ends (B) are provided on coil ends of the upper exposed wiring portions (16), and are opened without being engaged with wiring portions.

26. The high tension coil spring structure according to claim 18, wherein a number of turns of the upper exposed wiring portions (16) ranges from 3 to 6.

27. The high tension coil spring structure according to claim 18, wherein wiring portions of the upper exposed wiring portions (16) have a round shape.

28. The high tension coil spring structure according to claim 18, wherein the upper exposed wiring portions (16) have one or two convex portions which increase an inner diameter of wiring portions of the upper exposed wiring portions (16).

29. The high tension coil spring structure according to claim 18, wherein the rigid support ends (18) are disposed at a right angle with respect to the upper and/or lower end wiring portions (14, 14′).

30. The high tension coil spring structure according to claim 18, wherein the rigid support ends (18) are disposed at an acute angle with respect to the upper and/or lower end wiring portions (14, 14′).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1A and FIG. 1B are views showing the assembled state of a spring assembly of the related art, in which FIG. 1A is a perspective view showing the assembled state of the spring assembly, and FIG. 1B is a cross-sectional view showing the assembled state of the spring assembly;

[0031] FIG. 2 is a cross-sectional view illustrating creation of noise from the coil spring of the related art;

[0032] FIG. 3A, FIG. 3B and FIG. 3C are cross-sectional views of coil springs for preventing frictional noise that were previously invented by the applicant;

[0033] FIG. 4A, FIG. 4B, FIG. 4C and FIG. 4D are views showing the engaged state of a spring assembly according to the present invention, in which FIG. 4A is a cross-sectional view showing the engaged state of the spring assembly, and FIG. 4B to FIG. 4D are perspective views showing the engaged state of the spring assembly;

[0034] FIG. 5A and FIG. 5B are first conceptual views showing a process in which an upper exposed wiring portion of a coil spring according to the present invention is compressed, upper and lower end wiring portions of the coil spring having the shape of a round spring, in which FIG. 5A is a cross-sectional view showing the process in which the coil spring is compressed, and FIG. 5B is a perspective view showing the process in which the coil spring is compressed;

[0035] FIG. 6A and FIG. 6B are views showing a coil spring according to the present invention in which upper and lower end wiring portions have the shape of a round spring and a rigid support end is formed in a body wiring portion, in which FIG. 6A is a cross-sectional view showing first to fifth embodiments of the coil spring, and FIG. 6B is a perspective view showing the showing first to fifth embodiments of the coil spring;

[0036] FIG. 7A and FIG. 7B are second conceptual views showing a process in which an upper exposed wiring portion of a coil spring according to the present invention is compressed, upper and lower end wiring portions of the coil spring having the shape of an offset spring, in which FIG. 7A is a cross-sectional view showing the process in which the coil spring is compressed, and FIG. 7B is a perspective view showing the process in which the coil spring is compressed;

[0037] FIG. 8A and FIG. 8B are views showing a coil spring according to the present invention in which upper and lower end wiring portions have the shape of an offset spring and a rigid support end is formed in a body wiring portion, in which FIG. 8A is a cross-sectional view showing sixth to tenth embodiments of the coil spring, and FIG. 8B is a perspective view showing the showing sixth to tenth embodiments of the coil spring;

[0038] FIG. 9A and FIG. 9B are third conceptual views showing a process in which an upper exposed wiring portion of a coil spring according to the present invention is compressed, upper and lower end wiring portions of the coil spring having the shape of a round-offset spring, in which FIG. 9A is a cross-sectional view showing the process in which the coil spring is compressed, and FIG. 9B is a perspective view showing the process in which the coil spring is compressed;

[0039] FIG. 10A and FIG. 10B are views showing a coil spring according to the present invention in which upper and lower end wiring portions have the shape of a round-offset spring and a rigid support end is formed in a body wiring portion, in which FIG. 10A is a cross-sectional view showing eleventh to fifteenth embodiments of the coil spring, FIG. 10B is a perspective view showing the showing the eleventh to fifteenth embodiments of the coil spring;

[0040] FIG. 10C is a perspective view showing coil springs according to the present invention, in one of which a coil end of a lower end wiring portion forms a linear free end B which is opened without being engaged with a wiring portion, and in another one of which a coil end of an upper exposed wiring portion forms a linear free end B which is opened without being engaged with a wiring portion;

[0041] FIG. 11A, FIG. 11B and FIG. 11C are perspective views showing coil springs according to the present invention in each of which a handcuff portion C is formed on a coil end of a lower end wiring portion so as to engage with a wiring portion, in which FIG. 11A is a perspective view showing the coil spring in which the number of turns of the exposed wiring portion is 4, FIG. 11B is a perspective view showing the coil spring in which the number of turns of the exposed wiring portion is 5, and , FIG. 11C is a perspective view showing the coil spring in which the number of turns of the exposed wiring portion is 6;

[0042] FIG. 12A and FIG. 12B are views showing a coil spring according to the present invention in which upper and lower end wiring portions have the shape of a round spring and a rigid support end is formed in at least one of upper and lower exposed wiring portions, in which FIG. 12A is a cross-sectional view showing sixteenth to nineteenth embodiments of the coil spring, FIG. 12B is a perspective view showing the showing the sixteenth to nineteenth embodiments of the coil spring;

[0043] FIG. 13A and FIG. 13B are views showing a coil spring according to the present invention in which upper and lower end wiring portions have the shape of an offset spring and a rigid support end is formed in at least one of upper and lower exposed wiring portions, in which FIG. 13A is a cross-sectional view showing twentieth to twenty third embodiments of the coil spring, FIG. 13B is a perspective view showing the showing the twentieth to twenty third embodiments of the coil spring; and

[0044] FIG. 14A and FIG. 14B are views showing a coil spring according to the present invention in which upper and lower end wiring portions have the shape of a round-offset spring and a rigid support end is formed in at least one of upper and lower exposed wiring portions, in which FIG. 14A is a cross-sectional view showing twenty fourth to twenty seventh embodiments of the coil spring, FIG. 14B is a perspective view showing the showing the twenty fourth to twenty seventh embodiments of the coil spring.

DETAILED DESCRIPTION OF THE INVENTION

[0045] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below.

[0046] As shown in FIG. 4A to FIG. 14B, the present invention provides a high tension coil spring structure for a bed mattress having means for preventing friction noise. The high tension coil spring structure includes body wiring portions 12 which are disposed regularly at preset distances from each other in the space between an upper edge member 20 and a lower edge member 20′, upper and lower end wiring portions 14 and 14′ which are provided on both ends of the body wiring portions 12 and set within the range in which the upper and lower edge members 20 and 20′ are disposed, upper and lower exposed wiring portions 16 and 16′ which extend from at least one of the upper and lower end wiring portions 14 and 14′ so as to be exposed from the upper or lower edge members 20 or 20′, diameter-increasing portions A which are provided on at least one of the upper and lower end wiring portions 14 and 14′ and define spaces in which upper and lower exposure start wiring portions 16-5 and 16-5′ of the upper and lower exposed wiring portions 16 and 16′ move upward and downward while the coil spring structure is being compressed, and means for preventing friction noise which are provided on at least one of the upper and lower end wiring portions 14 and 14′. The means for preventing friction noise include rigid support ends 18 which are provided on at least one of the body wiring portion 12 and the upper and lower exposed wiring portions 16 and 16′, and absorb shock by absorbing a compressive load applied from the upper and lower exposed wiring portions 16 and 16′. Since the diameter-increasing portions A provide spaces in which upper and lower exposure start wiring portions 16-5 and 16-5′ move upward and downward while the coil spring structure is being compressed, frictional noise between the upper and lower end wiring portions 14 and 14′ and the upper and lower exposure start wiring portions 16-5 and 16-5′ is prevented. When a compressive load is applied to the coil spring structure, a plurality of wiring portions formed in the upper and lower exposed wiring portions 16 and 16′ move upward and downward along the side walls of the rigid support ends 18, thereby increasing elasticity.

[0047] Here, since the upper and lower edge members 20 and 20′ and the helical coils 30 are well-known in the art, they will be described using the same reference numerals and signs as in FIG. 1A, FIG. 1B and FIG. 2. Disclosure will be limited to coil springs 10 which are sequentially disposed between the upper and lower edge members 20 and 20′.

[0048] In addition, the coil springs 10 can be implemented as round coil springs, as shown in FIG. 5A, FIG. 5B, FIG. 6A and FIG. 6B, offset coil springs, as shown in FIG. 7A, FIG. 7B, FIG. 8A and FIG. 8B, or round-offset coil springs, as shown in FIG. 9A, FIG. 9B, FIG. 10A, FIG. 10B and FIG. 10C, depending on the shape of the upper and lower end wiring portions 14 and 14′ and the structure of the wiring portions.

[0049] In addition, when the coil springs 10 are implemented as the round coil springs, the upper exposed wiring portions 16 can be configured as shown in part (a) of FIG. 6A and FIG. 6B (first embodiment), the lower exposed wiring portions 16′ can be configured as shown in part (b) of FIG. 6A and FIG. 6B (second embodiment), or both the upper exposed wiring portions 16 and the lower exposed wiring portions 16′ can be configured as shown in parts (c) to (e) of FIG. 6A and FIG. 6B (third to fifth embodiments).

[0050] Furthermore, when the coil springs 10 are implemented as the offset coil springs, the upper exposed wiring portions 16 can be configured as shown in part (a) of FIG. 8A and FIG. 8B (sixth embodiment), the lower exposed wiring portions 16′ can be configured as shown in part (b) of FIG. 8A and FIG. 8B (seventh embodiment), or both the upper exposed wiring portions 16 and the lower exposed wiring portions 16′ can be configured as shown in parts (c) to (e) of FIG. 8A and FIG. 8B (eighth to tenth embodiments).

[0051] In addition, when the coil springs 10 are implemented as the round-offset coil springs, the upper exposed wiring portions 16 can be configured as shown in part (a) of FIG. 10A and FIG. 10B (eleventh embodiment), the lower exposed wiring portions 16′ can be configured as shown in part (b) of FIG. 10A and FIG. 10B (twelfth embodiment), or both the upper exposed wiring portions 16 and the lower exposed wiring portions 16′ can be configured as shown in parts (c) to (e) of FIG. 10A and FIG. 10B (thirteenth to fifteenth embodiments).

[0052] The diameter-increasing portions A can be applied to any type of the coil springs 10 which are used in the field of bed mattresses in place of the round coil springs, the offset coil springs, or the round-offset coil springs, and this structure, of course, belongs to the scope of the present invention.

[0053] In addition, each of the coil springs 10 includes the body wiring portion 12, the upper and lower end wiring portions 14 and 14′, the upper and lower exposed wiring portions 16 and 16′ and the rigid support ends 18. In particular, the diameter-increasing portion A is provided on at least one of the upper and lower end wiring portions 14 and 14′.

[0054] The body wiring portion 12 refers to the wiring portion which forms the main body of the coil spring 10 to support the entire load applied to the coil spring 10. The body wiring portion 12 is interposed in the vertical direction in the space between the upper and lower edge members 20 and 20′ in order to absorb the weight of a user. The body wiring portion 12 can have a variety of shapes including the shape of a double-headed drum.

[0055] In addition, the upper and lower end wiring portions 14 and 14′ refer to the wiring portions which are respectively formed on the upper and lower ends of the body wiring portions 12 so as to extend in the horizontal direction and are positioned within the range in which the upper and lower edge members 20 and 20′ are disposed. The upper and lower end wiring portions 14 and 14′ are butted to the upper and lower edge members 20, and are fixed using fixing pins or helical coils.

[0056] Here, the upper and lower end wiring portions 14 and 14′ can be formed at an angle of incline that deviates from the horizontal state, depending on the angle of incline of the upper and lower exposed wiring portions 16 and 16′, and this structure also belongs to the scope of the present invention.

[0057] Although the wiring portions are formed at a slightly inclined angle, the upper and lower end wiring portions 14 and 14′ can be horizontally set when they are butted to and engaged with the upper and lower edge members 20 and 20′ using the helical coils 30.

[0058] In addition, the lower end wiring portion 14′ may form a linear free end B on the coil end thereof which is opened without being engaged with the wiring portion, as shown in FIG. 10C, or a handcuff portion C on the coil end thereof which is engaged with the wiring portion, as shown in FIG. 11A, FIG. 11B and FIG. 11C.

[0059] In addition, as shown in FIG. 11A to FIG. 11C, it is preferred that the upper and lower end wiring portions 14 and 14′ have a round, offset or round-offset shape. In particular, one or two convex portions D which increase the inner diameter of the wiring portion may be formed on the upper and/or lower end wiring portions 14 and 14′, and this belongs to the scope of the present invention.

[0060] Although it is, of course, possible to make the upper and dower end wiring portions 14 and 14′ having the same shape, the upper and lower end wiring portions having different shapes also belong to the scope of the present invention.

[0061] In addition, the upper and lower exposed wiring portions 16 and 16′ refer to the wiring portions which extend from the upper end wiring portions 14 and/or the lower end wiring portions 14′ and cooperate with the body wiring portions 12 in order to absorb a load applied to the bed mattress. The upper and lower exposed wiring portions 16 and 16′ are wound such that their diameter is smaller than the diameter of the body wiring portions 12.

[0062] In this case, the body wiring portions 12 absorb shock in response to a large load applied to the bed mattress, whereas the upper and lower exposed wiring portions 16 and 16′ absorb shock in response to a smaller load applied to the bed mattress.

[0063] Here, the upper and lower exposure start wiring portions 16-5 and 16-5′ formed on the upper and lower exposed wiring portions 16 and 16′ refer to the portions of the upper and lower exposed wiring portions 16 and 16′ which are positioned close to the upper and lower end wiring portions 14 and 14′.

[0064] Although the number of turns of the upper and lower exposed wiring portions 16 and 16′ is preferably 3 to 6, as shown in FIG. 11A to FIG. 11C, in order to induce high tension to the coil springs 10, the number of turns greater than 6 also belongs to the scope of the present invention.

[0065] In addition, as shown in FIG. 11A to FIG. 11C, it is preferred that the upper and lower exposed wiring portions 16 and 16′ have a round shape. The upper and lower exposed wiring portions may also have an offset shape or a round-offset shape. The upper and lower exposed wiring portions 16 and 16′ may have one or two convex portions D which increase the inner diameter of the wiring portions without departing from the scope of the present invention. Of course, as shown in FIG. 10C and FIG. 12B, it is preferred that the linear free end B be formed on the coil end of at least one of the upper and lower exposed wiring portions 16 and 16′. In particular, the handcuff portion C may be formed in place of the linear free end B without departing from the scope of the present invention. pow The diameter-increasing portions A are configured so as to increase the inner diameter of the upper and lower end wiring portions 14 and 14′, thereby defining spaces through which the upper and lower exposure start wiring portions 16-5 and 16-5′ can move upward and downward while fundamentally preventing frictional noise. It is preferred that the diameter-increasing portions A be provided by increasing the inner diameter of the upper and lower end wiring portions 14 and 14′ so as to be greater than the outer diameter of the upper and lower exposure start wiring portions 16-5 and 16-5′.

[0066] In addition, as shown in FIG. 12A, FIG. 12B, FIG. 13A, FIG. 13B, FIG. 14A and FIG. 14B, when the upper and lower exposed wiring portions 16 and 16′ are provided with the rigid support ends 18, it is preferred that the inner diameter of the upper and lower end wiring portions 14 and 14′ having the diameter-increasing portion A be greater than the outer diameter of the body wiring portion 12 in order to introduce the upper and lower exposed wiring portions 16 and 16′ to move upward and downward along the outer circumference of the body wiring portion 12.

[0067] In addition, the wiring of the upper and lower end wiring portions 14 and 14′ can be formed so as to be inclined at a preset angle with respect to the horizontal surface in the process in which the diameter-increasing portions A are formed. Consequently, there is no contact between the upper and lower end wiring portions 14 and 14′ and the upper and lower exposure start wiring portions 16-5 and 16-5′, thereby preventing friction noise. This structure belongs to the scope of the present invention.

[0068] Furthermore, although the shape of the diameter-increasing portions A may correspond to the shape of the upper and lower end wiring portions 14 and 14′, it is preferred that the diameter-increasing portions A can have a round shape considering the structural characteristics of the coil springs 1.

[0069] In addition, the rigid support ends 18 are provided on at least one of the body wiring portions 12 and the upper and lower exposed wiring portions 16 and 16′ so as to absorb a compressive load. When a small load is applied to the bed mattress, the rigid support ends 18 absorb the compressive load using the upper and lower exposed wiring portions 16 and 16′. In contrast, when a large load is applied to the bed mattress, the upper and lower exposed wiring portions 16 and 16′ absorb most of the load, and the body wiring portions 12 absorb the remaining load, thereby preventing frictional noise while significantly increasing elasticity.

[0070] As shown in parts (a) and (b) of FIG. 6A and FIG. 6B, parts (a) and (b) of FIG. 8A and FIG. 8B, and parts (a) and (b) of FIG. 10A and FIG. 10B, one rigid support end 18 can be provided on the upper or lower portion of each of the body wiring portions 12. In addition, as shown in part (e) of FIG. 6A and FIG. 6B, part (e) of FIG. 8A and FIG. 8B, and part (e) of FIG. 10A and FIG. 10B, the rigid support ends 18 can also be respectively provided between the upper end wiring portions 14 and the lower end wiring portions 14′.

[0071] As shown in parts (c) and (d) of FIG. 6A and FIG. 6B, parts (c) and (d) of FIG. 8A and FIG. 8B, and parts (c) and (d) of FIG. 10A and FIG. 10B, a plurality of rigid support ends 18 can also be provided on each of the body wiring portions 12 such that the rigid support ends 18 are spaced apart predetermined distances from each other. This structure, of course, belongs to the technical scope of the present invention.

[0072] It is, of course, possible that the rigid support ends 18 be formed on the upper and lower exposed wiring portions 16 and 16′, as shown in FIG. 12A and FIG. 12B (sixteenth to nineteenth embodiments), FIG. 13A and FIG. 13B (twentieth to twenty third embodiments) and FIG. 14A and FIG. 14B (twenty fourth to twenty seventh embodiments). This structure, of course, belongs to the technical scope of the present invention.

[0073] In addition, it is preferred that the rigid support ends 18 be provided at a right or acute angle with respect to the upper and lower end wiring portions 14 and 14′ or the horizontal surface.

[0074] A description will be given below of the operation of the present invention.

[0075] First, since the process of fabricating the spring assembly 1 and the process of fabricating a bed mattress to which the spring assembly 1 is applied are well known in the art, descriptions thereof will be omitted. Disclosure will be limited to the structure of the coil springs 10 that prevents frictional noise and increases elasticity.

[0076] In particular, the operating structure will be described on assumption that the coil springs 10 having the structure of the present invention is applied to the bed mattress.

[0077] As shown in part (a) of FIG. 5A and FIG. 5B, part (a) of FIG. 7A and FIG. 7B and part (a) of FIG. 9A and FIG. 9B, if no load is applied to the bed mattress to which the coil spring 10 is applied, the upper exposed wiring portion 16 is set such that it protrudes above the upper edge member 20 and stays at that position.

[0078] In contrast, as shown in part (b) of FIG. 5A and FIG. 5B, part (b) of FIG. 7A and FIG. 7B and part (b) of FIG. 9A and FIG. 9B, when a small load from the user is applied to the bed mattress to which the coil spring 10 is applied, the upper exposed wiring portion 16 is depressed downward to the amount corresponding to the compressive load, thereby absorbing the compressive load.

[0079] In particular, as shown in part (c) of FIG. 5A and FIG. 5B, part (c) of FIG. 7A and FIG. 7B and part (c) of FIG. 9A and FIG. 9B, when a large load is applied to the bed mattress to which the coil spring 10 is applied, the upper exposure start wiring portions 16-5 of the upper exposed wiring portion 16 moves downward through the diameter-increasing portion A, thereby absorbing the compressive load.

[0080] In addition, as shown in parts (d) and (e) of FIG. 5A and FIG. 5B, parts (d) and (e) of FIG. 7A and FIG. 7B and parts (d) and (e) of FIG. 9A and FIG. 9B, when a stronger load is applied to the bed mattress to which the coil spring 10 is applied, the upper exposure start wiring portion 16-5 of the upper exposed wiring portion 16 moves further downward through the diameter-increasing portion A such that the range in which the upper exposed wiring portion 16 moves upward and downward is maximized, thereby maximizing the shock-absorbing efficiency.

[0081] Since the diameter-increasing portion A of the upper end wiring portion 14 defines the space where the upper exposure start wiring portion 16-5 can move upward and downward, the upper exposure start wiring portion 16-5 does not come into contact with the upper end wiring portion 14 while moving upward and downward.

[0082] At this time, when a strong load is applied to the bed mattress, due to the rigid support end 18 of the coil spring 10, the upper and lower exposed wiring portions 16 and 16′ absorb most of the load and the body wiring portion 12 absorbs the remaining load, thereby preventing frictional noise and significantly increases elasticity.

[0083] Now Accordingly, when a strong load is applied to the bed mattress to which the coil spring 10 is applied, the diameter-increasing portion A of the upper end wiring portion prevents friction noise between the upper end wiring portion 14 and the other portions of the coil spring 10 and significantly increases the elasticity of the exposed wiring portions 16 and 16′ which are formed as a plurality of wiring portions, thereby increasing the longevity of a product and improving the quality of the product.

[0084] The foregoing descriptions of the specific exemplary embodiments of the present invention have been presented for the purposes of illustration with reference to the accompanying drawings. A person having ordinary skill in the art will appreciate that various modifications and alternatives are possible without departing from the scope of the present invention that shall be defined by the Claims appended hereto and their equivalents.