Coil spring for bed mattress having means for preventing friction noise

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priorities from Korean Patent Application Number 10-2013-33188 filed on March 28 2013 and Korean Patent Application Number 10-2013-38366 filed on April 9, 2013, claiming priority from Korean Patent Application Number 10-2013-33188 filed on March 28 2013, the entire contents of which are incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a coil spring for a bed mattress having an exposed wiring portion which is formed on the coil spring for a bed mattress and works together with a spring body to absorb an external load, and more particularly, to a coil spring for a bed mattress having means for preventing frictional noise which can prevent the noise that is created by the friction between an exposed wiring portion and a surrounding wiring portion while the exposed wiring portion is being compressed.

Description of Related Art

In General, a bed mattress is an instrument for sleeping which provides a cushion or a buffering force using cushion members which are respectively stacked on the upper surface and the undersurface of a spring assembly. The spring assembly includes a plurality of coil springs which are provided between upper and lower frames inside the bed mattress and are regularly disposed at preset distances in the column and row directions.

In addition, "exposed wire springs" were developed and have been used as means for enhancing the cushioning and buffering force of the bed mattress. The exposed wire springs include coil springs which are disposed in the top-bottom direction between the upper and lower edge members such that the coil springs protrude above the upper edge member.

For instance, as shown in FIG. 1, a spring assembly 1 includes upper and lower edge members 20 and 20', coil springs 10 which are arranged in row and column directions R and C within the space between the upper edge member 20 and the lower edge member 20', and helical coils 30 which are spirally engaged with the coil springs 10 in the row direction R.

In addition, as shown in FIG. 2, each of the coil springs 10 includes a body wiring portion 12 situated in a space between the upper edge member 20 and the lower edge member 20', end wiring portions 14 provided on both ends of the body wiring portion 12 so as to be engaged with the upper and lower edge members 20 and 20', and an exposed wiring portion 16 extending from one of the end wiring portions 14 so as to be exposed from the edge member 20.

Here, in the case of attempting to set the spring assembly 1, when the helical coils 30 are engaged in the state in which the coil springs 10 are set at preset distances from each other between the edge members 20 and 20', the exposed wiring portions 16 are set such that they protrude above the upper edge member 20 or below the lower edge member 20'.

In addition, when the spring assembly 1 is applied to a bed mattress, the exposed wiring portions 16 absorbs shock when a small load is applied in response to, for example, rolling over of a mattress user, and the body wiring portions 12 absorb shock when a large load is applied from the mattress user.

The coil springs 12 advantageously increase the comfort and convenience of the user since the exposed wiring portions 16 and the body wiring portions 12 properly distribute the shock-absorbing function in response to variation in the load applied to the bed mattress. However, the coil springs 12 have at least the following problems.

First, as shown in FIG. 3, in the process in which the coil spring 10 is compressed at the moment that the bed mattress is subjected to a load, a contact wiring portion 16-5 of the exposed wiring portion 16 abuts to the end wiring portion 14 which is positioned below while moving down. This consequently creates noise due to contact between the exposed wiring portion 16 and the end wiring portion 14.

Second, when a large load is applied to the bed mattress, the exposed wiring portion 16 of the spring assembly is compressed, and concurrently, the body wiring portion 12 is compressed at a high speed. Rapid compression of the exposed wiring portion 16 increases the friction between the exposed wiring portion 16 and the end wiring portion 14, thereby creating frictional noise.

In addition, Korean Patent No. 10-0444347 (United States Patent No. 6,983,503) disclosed means for preventing frictional noise in the coil spring 10. The means for preventing frictional noise includes foaming the exposed wiring portions. Foaming of the exposed wiring portions of the coil spring 10 leads to an advantage in that the interference between the upper and/or lower edge members and the exposed wiring portions of the coil spring is completely prevented, thereby preventing frictional noise. However, there are drawbacks in that the process of foaming the exposed wiring portions is added, a cost for purchasing equipment which seals the exposed wiring portions by foaming increases, and costs for the material and the process for the foaming and sealing increase.

Accordingly, solutions for preventing stress due to frictional noise between the exposed wiring portions 16 and the end wiring portions 14 while the bed mattress is being used and for increasing the longevity of the coil spring are urgently required

The information disclosed in the Background of the Invention section is provided only for better understanding of the background of the invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art.

Related Art Document

• Patent Document 1: Korean Patent No. 10-0444347 (patented April 30, 2004)
• Patent Document 2: United States Patent No. 6,983,503 (patented January 10, 2006)

BRIEF SUMMARY OF THE INVENTION

Various aspects of the present invention provide a coil spring for a bed mattress having means for preventing frictional noise which can prevent the noise that is created due to the friction between an exposed wire portion which protrudes upward or downward from a spring assembly and a surrounding wiring portion while the exposed wiring portion is being compressed.

In an aspect of the present invention, provided is a coil spring for a bed mattress having means for preventing frictional noise which includes a body wiring portion situated in the space between an upper edge member and a lower edge member, an end wiring portion provided on both ends of the body wiring portion and set within a range in which the upper and lower edge members are disposed, and means for preventing frictional noise which include at least one of an upper exposed wiring portion extending from the end wiring portion so as to be exposed from the upper edge member and a lower exposed wiring portion extending from the end wiring portion so as to be exposed from the lower edge member. At least one of contact wiring portions of the upper and lower exposed wiring portions which abut to the end wiring portions while the upper and lower exposed wiring portion are being compressed has a contact surface which is in contact with one corresponding end wiring portion of the end wiring portions, whereby frictional noise between the exposed wiring portion and the end wiring portion is prevented.

In another aspect of the present invention, provided is a coil spring for a bed mattress having means for preventing frictional noise which includes a body wiring portion situated in the space between an upper edge member and a lower edge member, an end wiring portion provided on both ends of the body wiring portion and set within a range in which the upper and lower edge members are disposed, and means for preventing frictional noise which include at least one of an upper exposed wiring portion extending from the end wiring portion so as to be exposed from the upper edge member and a lower exposed wiring portion extending from the end wiring portion so as to be exposed from the lower edge member. The coil spring further includes at least one rigid support end which is provided on the body wiring portion or the upper or lower exposed wiring portion so as to absorb a compressive load. At least one of contact wiring portions of the upper and lower exposed wiring portions which abut to the end wiring portions while the upper and lower exposed wiring portion are being compressed has a contact surface which is in contact with one corresponding end wiring portion of the end wiring portions, whereby frictional noise between the exposed wiring portion and the end wiring portion is prevented.

As set forth above, the present invention has at minimum the following effects.

First, since the coil spring is provided with the contact surface where the exposed wiring portion abuts to the end wiring portion such that the contact state is maintained or the contact point, where the exposed wiring portion abuts to the end wiring portion, is fixed, it is possible to remove friction that is created due to contact between the exposed wiring portion and the end wiring portion while the exposed portion is being compressed, thereby preventing noise.

Second, since the coil spring is provided with the contact surface where the exposed wiring portion abuts to the end wiring portion such that the contact state is maintained or the contact point where the exposed wiring portion abuts to the end wiring portion is fixed, the exposed wiring portion and the body wiring portion move only upward and downward without being displaced or deformed in the lateral direction, thereby increasing longevity.

Third, in the state where frictional noise between the exposed wiring portion and the end wiring portion of the coil spring is minimized, small and large loads applied to the bed mattress are discriminated and a suitable level of buffering force is provided, thereby improving the quality of a product.

Fourth, the process of foaming the exposed wiring portion, which was proposed in Korean Patent No. 10-0444347 and United States Patent No. 6,983,503 as means for preventing frictional noise in the coil spring, becomes unnecessary. It is possible to preclude equipment which seals the exposed wiring portion and the sealing process as well as reduce the price for purchasing that equipment and the cost for the process, thereby improving productivity.

Fifth, the coil springs were provided with the contact surfaces, at each of which the exposed wiring portion and the end wiring portion abutted to and stayed in contact with each other, and were applied to the above-mentioned bed mattress, and frictional noise was measured. Consequently, it was noted that frictional noise was significantly reduced as presented in the results in the "Certificate of Analysis" validated by the internationally recognized testing laboratory.

Here, among test samples presented in the "Test Report on Measurement of Noise in Spring Plate" attached to the "Certificate of Analysis," Samples A-1 and B-1 indicate bed mattresses to which the coil spring shown in FIG. 1 to 3 were applied, Samples A-2, B-2 and C-2 indicate bed mattresses to which the coil spring proposed in Korean Patent No. 10-0444347 was applied, and Samples A-3, B-3 and C-3 indicate bed mattresses to which the coil springs shown in FIG. 4 to FIG. 13 were applied.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from, or are set forth in greater detail in the accompanying drawings, which are incorporated herein, and in the following

Detailed Description of the Invention, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

• FIG. 1 is an overall perspective view showing a spring assembly of the related art;
• FIG. 2 is a cross-sectional view showing the spring assembly of the related art;
• FIG. 3 is a cross-sectional view illustrating creation of noise from the coil spring of the related art;
• FIG. 4A to FIG. 4D show applications of a spring assembly of the present invention, in which FIG. 4A is a cross-sectional view showing an application of a spring assembly of the present invention, FIG. 4B is a perspective view showing the state in which offset springs are disposed, FIG. 4C is a perspective view showing the state in which round springs are disposed, and FIG. 4D is a perspective view in which round offset springs are disposed;
• FIG. 5 is a cross-sectional and perspective view showing a first embodiment of the coil spring according to one application of the present invention;
• FIG. 6 is a cross-sectional and perspective view showing a second embodiment of the coil spring according to one application of the present invention;
• FIG. 7 is a cross-sectional and perspective view showing a third embodiment of the coil spring according to one application of the present invention;
• FIG. 8A to Fig. 8D show other applications of a spring assembly of the present invention, in which FIG. 8A is a cross-sectional view showing an application of a spring assembly of the present invention, FIG. 8B is a perspective view showing the state in which offset springs are disposed, FIG. 8C is a perspective view showing the state in which round springs are disposed, and FIG. 8D is a perspective view in which round offset springs are disposed;
• FIG. 9 is a cross-sectional and perspective view showing a fourth embodiment of the coil spring according to another application of the present invention;
• FIG. 10 is a cross-sectional and perspective view a fifth embodiment of the coil spring according to another application of the present invention;
• FIG. 11 is a cross-sectional and perspective view showing a sixth embodiment of the coil spring according to another application of the present invention;
• FIG. 12 is a cross-sectional and perspective view showing a seventh embodiment of the coil spring according to another application of the present invention; and
• FIG. 13 is a cross-sectional and perspective view showing an eighth embodiment of the coil spring according to another application of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

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.

First, among components of the present invention, since an upper edge member 20, a lower edge member 20' and helical coils 30 have substantially the same function as those shown in FIG. 1 to FIG. 3, they will be described with reference to the same reference numerals.

In addition, in the accompanying drawings of the present invention, FIG. 4 to FIG. 7 show coil springs 10 which do not include a rigid support end 18, and FIG. 8 to 13 show coils springs 10 which include at least one rigid support end 18.

In addition, FIG. 4 to FIG. 13 of the present invention show the state in which end wiring portions 14 are in contract with exposed wiring portions 16 and 16'.

A description will be given below of first to eighth embodiments of the present invention.

Embodiment 1

FIG. 5 is a cross-sectional and perspective view showing a first embodiment of the coil spring of the spring assembly according to the present invention.

This embodiment of the present invention provides a coil spring for a bed mattress having means for preventing frictional noise which includes a body wiring portion 12 situated in the space between the upper edge member 20 and the lower edge member 20', the end wiring portions 14 provided on both ends of the body wiring portion 12 and set within a range in which the upper and lower edge members 20 and 20' are disposed, and at least one of the upper exposed wiring portion 16 extending from the end wiring portion 14 so as to be exposed from the upper edge member 20 and the lower exposed wiring portion 16' extending from the end wiring portion 14 so as to be exposed from the lower edge member 20'.

Here, contact wiring portions 16-5 and 16-5' which abut to the end wiring portions 14 while the upper and lower exposed wiring portions 16 and 16' are being compressed have contact surfaces A which are set in contact with the end wiring portions 14, whereby frictional noise between the upper and lower exposed wiring portions 16 and 16' and the end wiring portions 14 is prevented.

First, since the upper and lower edge members 20 and 20' and the helical coils 30 are well-known in the art, detailed descriptions thereof will be omitted. Disclosure will be limited to the coil springs 10 which are sequentially disposed between the upper and lower edge members 20 and 20'.

In addition, the coil spring 10 according to this embodiment indicates the spring having the upper exposed wiring portion 16 and the lower exposed wiring portion 16' which are respectively formed on the upper end and the lower end of the body wiring portion 12. In particular, the coil spring 10 is configured such that the contact wiring portion 16-5 of the upper exposed wiring portion 16 abuts to one of the end wiring portions 14 and the contact wiring portion 16-5' of the lower exposed wiring portion 16' abuts to the other one of the end wiring portions 14.

Since the contact wiring portions 16-5 and 16-5' are provided with the contact surfaces A having a preset length which stay in contact with the end wiring portions 14, the contact wiring portions 16-5 and 16-5' are set so as to stay in contact with the end wiring portions 14.

In addition, the body wiring portion 12 indicates the wiring portion which is situated in the vertical direction in the space between the upper and lower edge members 20 and 20' so as to support the load of the bed mattress. The wiring portion can have a variety of shapes including a double-headed drum, and such a variety of shapes belongs to the technical scope of the present invention.

Furthermore, the end wiring portions 14 indicate the wiring portions which are positioned within the range in which the edge members 20 and 20' are arranged when the end wiring portions are respectively formed on both ends of the body wiring portion 12 in the horizontal direction. The end wiring portions 14 are fixed to the edge members 20 and 20' via fixing pins or helical coils.

In addition, the exposed wiring portions 16 and 16' indicate the wiring portions which further extend from the end wiring portions 14 and are wound such that their diameter is smaller than the diameter of the body wiring portion 12. The exposed wiring portions 16 and 16' are characterized in that they are compressed with a load smaller than the body wiring portion 12.

Embodiment 2

FIG. 6 is a cross-sectional and perspective view showing a second embodiment of the coil spring of the spring assembly according to the present invention.

This embodiment of the present invention provides a coil spring for a bed mattress having means for preventing frictional noise which includes a body wiring portion 12 situated in a space between the upper edge member 20 and the lower edge member 20', the end wiring portions 14 provided on both ends of the body wiring portion 12 and set within a range in which the upper and lower edge members 20 and 20' are disposed, and the upper exposed wiring portion 16 extending from one of the end wiring portions 14 so as to be exposed from the upper edge member 20. Here, a contact wiring portion 16-5 which abuts to one of the end wiring portions 14 while the upper exposed wiring portion 16 is being compressed has a contact surface A which is in contact with that end wiring portion 14, whereby frictional noise between the upper exposed wiring portion 16 and that end wiring portion 14 is essentially prevented.

First, since the upper and lower edge members 20 and 20' and the helical coils 30 are well-known in the art, detailed descriptions thereof will be omitted. Disclosure will be limited to the coil springs 10 which are sequentially disposed between the upper and lower edge members 20 and 20'.

In addition, the coil spring 10 according to this embodiment indicates the spring having the upper exposed wiring portion 16 which is formed on the upper end of the body wiring portion 12. In particular, the coil spring 10 is configured such that the contact wiring portion 16-5 of the upper exposed wiring portion 16 abuts to one of the end wiring portions 14.

Since the contact wiring portion 16-5 is provided with the contact surface A having a preset length which stays in contact to one of the end wiring portions 14, the contact wiring portion 16-5 is set so as to stay in contact with that end wiring portion 14.

In addition, the body wiring portion 12 indicates the wiring portion which is situated in the vertical direction in the space between the upper and lower edge members 20 and 20' so as to support the load of the bed mattress. The wiring portion can have a variety of shapes including a double-headed drum, and such a variety of shapes belongs to the technical scope of the present invention.

Furthermore, the end wiring portions 14 indicate the wiring portions which are positioned within the range in which the edge members 20 and 20' are arranged when the end wiring portions are respectively formed on both ends of the body wiring portion 12 in the horizontal direction. The end wiring portions 14 are fixed to the edge members 20 and 20' via fixing pins or helical coils.

In addition, the upper exposed wiring portion 16 indicates the wiring portion which further extends from one of the end wiring portions 14 and is wound such that its diameter is smaller than the diameter of the body wiring portion 12. The upper exposed wiring portion 16 is characterized in that it is compressed with a load smaller than the body wiring portion 12.

Embodiment 3

FIG. 7 is a cross-sectional and perspective view showing a third embodiment of the coil spring of the spring assembly according to the present invention.

This embodiment of the present invention provides a coil spring for a bed mattress having means for preventing frictional noise which includes a body wiring portion 12 situated in a space between the upper edge member 20 and the lower edge member 20', the end wiring portions 14 provided on both ends of the body wiring portion 12 and set within a range in which the upper and lower edge members 20 and 20' are disposed, and the lower exposed wiring portion 16' extending from one of the end wiring portions 14 so as to be exposed from the lower edge member 20'. Here, a contact wiring portion 16-5' which abuts to one of the end wiring portions 14 while the lower exposed wiring portion 16' is being compressed has a contact surface A which is in contact with that end wiring portion 14, whereby frictional noise between the lower exposed wiring portion 16' and that end wiring portion 14 is essentially prevented.

First, since the upper and lower edge members 20 and 20' and the helical coils 30 are well-known in the art, detailed descriptions thereof will be omitted. Disclosure will be limited to the coil springs 10 which are sequentially disposed between the upper and lower edge members 20 and 20'.

In addition, the coil spring 10 according to this embodiment indicates the spring having the lower exposed wiring portion 16' which is formed on the lower end of the body wiring portion 12. In particular, the coil spring 10 is configured such that the contact wiring portion 16-5' of the lower exposed wiring portion 16' abuts to one of the end wiring portions 14.

Since the contact wiring portion 16-5' is provided with the contact surface A having a preset length which stays in contact to one of the end wiring portions 14, the contact wiring portion 16-5' is set so as to stay in contact with that end wiring portion 14.

In addition, the body wiring portion 12 indicates the wiring portion which is situated in the vertical direction in the space between the upper and lower edge members 20 and 20' so as to support the load of the bed mattress. The wiring portion can have a variety of shapes including a double-headed drum, and such a variety of shapes belongs to the technical scope of the present invention.

Furthermore, the end wiring portions 14 indicate the wiring portions which are positioned within the range in which the edge members 20 and 20' are arranged when the end wiring portions are respectively formed on both ends of the body wiring portion 12 in the horizontal direction. The end wiring portions 14 are fixed to the edge members 20 and 20' via fixing pins or helical coils.

In addition, the lower exposed wiring portion 16' indicates the wiring portion which further extends from one of the end wiring portions 14 and is wound such that its diameter is smaller than the diameter of the body wiring portion 12. The lower exposed wiring portion 16' is characterized in that it is compressed with a load smaller than the body wiring portion 12.

Embodiment 4 to Embodiment 6

FIG. 9 to FIG. 11 are cross-sectional and perspective views showing fourth to sixth embodiments of the coil spring of the spring assembly according to the present invention.

This embodiment of the present invention provides a coil spring for a bed mattress having means for preventing frictional noise which includes a body wiring portion 12 situated in a space between the upper edge member 20 and the lower edge member 20', the end wiring portions 14 provided on both ends of the body wiring portion 12 and set within a range in which the upper and lower edge members 20 and 20' are disposed, and at least one of the upper exposed wiring portion 16 extending from the end wiring portion 14 so as to be exposed from the upper edge member 20 and the lower exposed wiring portion 16' extending from the end wiring portion 14 so as to be exposed from the lower edge member 20'. The coil spring further includes one rigid support end 18 which is provided on the body wiring portion 12 or the upper or lower exposed wiring portions 16 and 16' so as to absorb a compressive load. Alternatively, a plurality of rigid support ends can be provided on the body wiring portion 12 or the upper or lower exposed wiring portions 16 and 16'. Contact wiring portions 16-5 and 16-5' which abut to the end wiring portions 14 while the upper and lower exposed wiring portions 16 and 16' are being compressed have contact surfaces A which are set in contact with the end wiring portions 14, whereby frictional noise between the upper and lower exposed wiring portions 16 and 16' and the end wiring portions 14 is prevented.

First, since the upper and lower edge members 20 and 20' and the helical coils 30 are well-known in the art, detailed descriptions thereof will be omitted. Disclosure will be limited to the coil springs 10 which are sequentially disposed between the upper and lower edge members 20 and 20'.

In addition, the coil spring 10 according to this embodiment indicates the spring having the upper exposed wiring portion 16 and the lower exposed wiring portion 16' which are respectively formed on the upper end and the lower end of the body wiring portion 12. In particular, the coil spring 10 is configured such that the contact wiring portion 16-5 of the upper exposed wiring portion 16 abuts to one of the end wiring portions 14 and the contact wiring portion 16-5' of the lower exposed wiring portion 16' abuts to the other one of the end wiring portions 14.

Since the contact wiring portions 16-5 and 16-5' are provided with the contact surfaces A having a preset length which stay in contact with the end wiring portions 14, the contact wiring portions 16-5 and 16-5' are set so as to stay in contact with the end wiring portions 14.

In addition, the body wiring portion 12 indicates the wiring portion which is situated in the vertical direction in the space between the upper and lower edge members 20 and 20'. so as to support the load of a bed mattress. The wiring portion can have a variety of shapes including a double-headed drum, and such a variety of shapes belongs to the technical scope of the present invention.

Furthermore, the end wiring portions 14. indicate the wiring portions which are positioned within the range in which the edge members 20 and 20' are arranged when the end wiring portions are respectively formed on both ends of the body wiring portion 12 in the horizontal direction. The end wiring portions 14 are fixed to the edge members 20 and 20' via fixing pins or helical coils.

In addition, the exposed wiring portions 16 and 16' indicate the wiring portions which further extend from the end wiring portions 14 and are wound such that their diameter is smaller than the diameter of the body wiring portion 12. The exposed wiring portions 16 and 16' are characterized in that they are compressed with a load smaller than the body wiring portion 12.

Furthermore, when a small load is applied to the bed mattress, the rigid support end 18 absorbs the compressive load using the exposed wiring portions 16 and 16'. When a large load is applied to the bed mattress, the rigid support end 18 prevents the load of the exposed wiring portions 16 and 16' from being transferred to the body wiring portion 12.

Although one rigid support end 18 can be provided on the upper or lower portion of the body wiring portion 12, a plurality of rigid support ends can be provided at preset intervals on the body wiring portion 12. This configuration of course belongs to the technical scope of the present invention.

In addition, when the rigid support end 18 is formed on at least one of the exposed wiring portions 16 and 16', this configuration of course belongs to the technical scope of the present invention.

In this case, the exposed wiring portions 16 and 16' can of course be implemented as a variety of shapes of wiring portions including a double-headed drum.

Furthermore, it is preferred that the rigid support end 18 be formed at a right angle or an acute angle with respect to the end wiring portion 14 or the horizontal plane.

Embodiment 7

FIG. 12 is a cross-sectional and perspective view showing a seventh embodiment of the coil spring according to the present invention.

This embodiment of the present invention provides a coil spring for a bed mattress having means for preventing frictional noise which includes a body wiring portion 12 situated in a space between the upper edge member 20 and the lower edge member 20', the end wiring portions 14 provided on both ends of the body wiring portion 12 and set within a range in which the upper and lower edge members 20 and 20' are disposed, and at least the upper exposed wiring portion 16 extending from the end wiring portion 14 so as to be exposed from the upper edge member 20. The coil spring further includes at least one rigid support end 18 which is provided on the body wiring portion 12 or the upper or lower exposed wiring portion 16 so as to absorb a compressive load. A contact wiring portion 16-5 which abuts to the end wiring portions 14 while the upper and lower exposed wiring portion 16 is being compressed has a contact surface A which is in contact with the end wiring portion 14, whereby frictional noise between the upper exposed wiring portion 16 and the end wiring portions 14 is essentially prevented.

First, since the upper and lower edge members 20 and 20' and the helical coils 30 are well-known in the art, detailed descriptions thereof will be omitted. Disclosure will be limited to the coil springs 10 which are sequentially disposed between the upper and lower edge members 20 and 20'.

In addition, the coil spring 10 according to this embodiment indicates the spring having the upper exposed wiring portion 16 which is formed on the upper end of the body wiring portion 12. In particular, the coil spring 10 is set such that the contact wiring portion 16-5 of the upper exposed wiring portion 16 stays in contact to one of the end wiring portions 14.

Since the contact wiring portion 16-5 is provided with the contact surface A having a preset length which stays in contact to one of the end wiring portions 14, the contact wiring portion 16-5 is set so as to stay in contact with that end wiring portion 14.

In addition, the body wiring portion 12 indicates the wiring portion which is situated in the vertical direction in the space between the upper and lower edge members 20 and 20' so as to support the load of the bed mattress. The wiring portion can have a variety of shapes including a double-headed drum, and such a variety of shapes belongs to the technical scope of the present invention.

Furthermore, the end wiring portions 14 indicate the wiring portions which are positioned within the range in which the edge members 20 and 20' are arranged when the end wiring portions are respectively formed on both ends of the body wiring portion 12 in the horizontal direction. The end wiring portions 14 are fixed to the edge members 20 and 20' via fixing pins or helical coils.

In addition, the upper exposed wiring portion 16 indicates the wiring portion which further extends from one of the end wiring portions 14 and is wound such that its diameter is smaller than the diameter of the body wiring portion 12. The upper exposed wiring portion 16 is characterized in that it is compressed with a load smaller than the body wiring portion 12.

Furthermore, when a small load is applied to the bed mattress, the rigid support end 18 absorbs the compressive load using the upper exposed wiring portion 16. When a large load is applied to the bed mattress, the rigid support end 18 prevents the load of the upper exposed wiring portion 16 from being transferred to the body wiring portion 12.

Although one rigid support end 18 can be provided on the upper or lower portion of the body wiring portion 12, a plurality of rigid support ends can be provided at preset intervals on the body wiring portion 12. This configuration of course belongs to the technical scope of the present invention.

In addition, when the rigid support end 18 is formed on at least one of the upper exposed wiring portion 16, this configuration of course belongs to the technical scope of the present invention.

In this case, the upper exposed wiring portion 16 can be implemented as a variety of shapes of wiring portions including a double-headed drum.

Furthermore, it is preferred that the rigid support end 18 be formed at a right angle or an acute angle with respect to the end wiring portion 14 or the horizontal plane.

Embodiment 8

FIG. 13 is a cross-sectional and perspective view showing an eighth embodiment of the coil spring of the spring assembly according to another application of the present invention.

This embodiment of the present invention provides a coil spring for a bed mattress having means for preventing frictional noise which includes a body wiring portion 12 situated in a space between the upper edge member 20 and the lower edge member 20', the end wiring portions 14 provided on both ends of the body wiring portion 12 and set within a range in which the upper and lower edge members 20 and 20' are disposed, and at least the lower exposed wiring portion 16' extending from the end wiring portion 14 so as to be exposed from the upper edge member 20. The coil spring further includes at least one rigid support end 18 which is provided on the body wiring portion 12 or the upper or lower exposed wiring portion 16' so as to absorb a compressive load. A contact wiring portion 16-5 which abuts to the end wiring portions 14 while the upper and lower exposed wiring portion 16 is being compressed has a contact surface A which is in contact with the end wiring portion 14, whereby frictional noise between the lower exposed wiring portion 16' and the end wiring portions 14 is essentially prevented.

First, since the upper and lower edge members 20 and 20' and the helical coils 30 are well-known in the art, detailed descriptions thereof will be omitted. Disclosure will be limited to the coil springs 10 which are sequentially disposed between the upper and lower edge members 20 and 20'.

In addition, the coil spring 10 according to this embodiment indicates the spring having the lower exposed wiring portion 16' which is formed on the lower end of the body wiring portion 12. In particular, the coil spring 10 is configured such that the contact wiring portion 16-5' of the lower exposed wiring portion 16 stays in contact with one of the end wiring portions 14.

Since the contact wiring portion 16-5' is provided with the contact surface A having a preset length which stays in contact with one of the end wiring portions 14, the contact wiring portion 16-5' is set so as to stay in contact with that end wiring portion 14.

In addition, the body wiring portion 12 indicates the wiring portion which is situated in the vertical direction in the space between the upper and lower edge members 20 and 20' so as to support the load of the bed mattress. The wiring portion can have a variety of shapes including a double-headed drum, and such a variety of shapes belongs to the technical scope of the present invention.

Furthermore, the end wiring portions 14 indicate the wiring portions which are positioned within the range in which the edge members 20 and 20' are arranged when the end wiring portions are respectively formed on both ends of the body wiring portion 12 in the horizontal direction. The end wiring portions 14 are fixed to the edge members 20 and 20' via fixing pins or helical coils.

In addition, the lower exposed wiring portion 16' indicates the wiring portion which further extends from one of the end wiring portions 14 and is wound such that its diameter is smaller than the diameter of the body wiring portion 12. The lower exposed wiring portion 16' is characterized in that it is compressed with a load smaller than the body wiring portion 12.

Furthermore, when a small load is applied to the bed mattress, the rigid support end 18 absorbs the compressive load using the lower exposed wiring portion 16'. When a large load is applied to the bed mattress, the rigid support end 18 prevents the load of the lower exposed wiring portion 16' from being transferred to the body wiring portion 12.

Although one rigid support end 18 can be provided on the upper or lower portion of the body wiring portion 12, a plurality of rigid support ends can be provided at preset intervals on the body wiring portion 12. This configuration of course belongs to the technical scope of the present invention.

In addition, when the rigid support end 18 is formed on at least one of the lower exposed wiring portion 16', this configuration of course belongs to the technical scope of the present invention.

In this case, the lower exposed wiring portion 16' can of course be implemented as a variety of shapes of wiring portions including a double-headed drum.

Furthermore, it is preferred that the rigid support end 18 be formed at a right angle or an acute angle with respect to the end wiring portion 14 or the horizontal plane.

The foregoing descriptions of the specific exemplary embodiments of the present invention have been presented for the purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable a person having ordinary skill in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.

In summary, an embodiment refers to a coil spring for a bed mattress. At least one of contact wiring portions 16-5 and 16-5' of the upper and lower exposed wiring portions 16 and 16' which abut to the end wiring portions 14 while the upper and lower exposed wiring portion 16, 16' are being compressed has a contact surface A which is in contact with one corresponding end wiring portion of the end wiring portions 14, whereby frictional noise between the exposed wiring portion 16, 16' and the end wiring portion 14 is prevented. It is possible to consequently remove friction that is created due to contact between the exposed wiring portion and the end wiring portion while the exposed portion is being compressed, thereby preventing noise. The exposed wiring portion and the body wiring portion move only upward and downward without being displaced or deformed in the lateral direction, thereby increasing longevity.