JP7790986B2 - Spring members and vibration-proof structures - Google Patents

Description

The present invention relates to a spring member and a vibration-damping structure.

In facilities such as music concert halls and dance studios, vertical vibrations caused by the bending and stretching movements of large numbers of patrons can be a problem (so-called vertical vibrations), and to address this, the floor in question is designed as a floating floor that is isolated from the foundation and other structural elements. In such vibration-isolation structures, the structure is partially recessed, and a floating floor supported by springs is installed in the recessed area.
The floating floor needs to be able to move vertically relative to the structure, and this is accommodated by the expansion and contraction of the support springs.

The vibration isolation performance of such floating floors increases as the ratio of the excitation frequency to the floating floor's natural frequency increases, based on the reaction force response magnification (= total reaction force R acting on the structure from the floating floor / excitation force F). For example, if the excitation frequency is 3.4 times or more the floating floor's natural frequency, the reaction force R can be made less than 1/10 of the excitation force F. Therefore, for excitation forces of 2 Hz or more, where vertical vibration becomes a problem, setting the floating floor's natural frequency to 0.6 Hz or less is effective. Because the frequency characteristics of the excitation source cannot be adjusted through design, improving vibration isolation effectiveness requires lowering the floating floor's natural frequency, which requires either increasing the floating floor's mass m or reducing the support spring stiffness k. Increasing the floating floor's mass also increases the floating floor's thickness, which increases the burden on the building foundation, making this undesirable. On the other hand, one way to reduce the support spring stiffness is to reduce the cross-section of the spring or increase its length, but reducing the cross-section reduces the spring strength, and increasing the spring length not only increases the length of the spring member, making it more susceptible to buckling under compressive force, but also increases the depth of the pit provided below the floating floor, increasing the excavation depth of the foundation and making this uneconomical.

For example, if a floating floor's natural frequency is 1 Hz and a support spring is used that sinks 250 mm under its own weight, then if the floating floor's natural frequency is 0.6 Hz, the support spring will sink 700 mm under its own weight. The free length of a spring (actual length before load is applied) is generally more than three times the deflection (amount of sinking), so if the floating floor's natural frequency is 1 Hz, the spring's free length will be 750 mm or more and will fit comfortably within the pit, but if it is 0.6 Hz, it will be 2,100 mm or more. Another problem is that a spring with a long free length is more likely to buckle when compressed.

The support springs for the floating floor that make up the vibration isolation mechanism are required to have high strength to support a heavy floating floor, as well as compact, low-rigidity spring characteristics that allow installation without increasing the distance between the floating floor and the foundation. In the vibration isolation structures disclosed in Patent Documents 1 and 2, reducing spring stiffness in a compact manner can be achieved by arranging springs with a specified strength in series so as not to increase the overall length; in the automotive field, concentrically nested springs are arranged in series to shorten the overall length of the spring members.

JP 2012-153367 A JP 2014-84091 A

However, when arranging such springs in a nested, concentric arrangement, the structure becomes complex and the spring shape is limited, making it impossible to use common commercially available springs, and making it difficult to construct spring components simply and inexpensively.

The present invention aims to provide a spring member and vibration-damping structure that can be constructed inexpensively with a simple structure.

To achieve the above object, the spring member of the present invention is disposed between a structure and a vibrating body disposed on the structure, and supports the vibrating body so that it can be displaced vertically relative to the structure. The spring member comprises a lower member fixed to the structure, an upper member disposed above the lower member facing the vibrating body and fixed to the vibrating body, a first spring that is vertically expandable and contractible and has a lower end connected to the lower member and an upper end not directly connected to the upper member but positioned below the upper member, a second spring that is vertically expandable and contractible and has an upper end connected to the upper member and a lower end not directly connected to the lower member but positioned above the lower member and below the upper end of the first spring, and a third spring that is vertically expandable and contractible and is disposed at a height that horizontally overlaps the first spring and the second spring, and has an upper end connected to the upper end of the first spring and a lower end connected to the lower end of the second spring.

To achieve the above objective, the vibration-damping structure of the present invention has a spring member provided between the structure and the vibrating body.

In the spring member of the present invention, the first spring, the second spring, and the third spring are arranged in series, which allows the spring stiffness to be reduced without reducing the spring support capacity (yield strength).
Three individual springs (first, second, and third springs) are connected in series and folded to a height that overlaps them horizontally. This reduces the axial stiffness of the composite spring to one-third, and the height of the combined individual springs is significantly reduced to less than three times the length of the individual springs, making it compact. As a result, the depth of the recess in the structure where the vibrating body is placed does not become excessive, and the depth of the foundation or other structure does not increase.
The first, second, and third springs do not need to be nested, but can simply be arranged in a plane, and common springs (such as coil springs or disc springs, the materials of which are readily available and inexpensive) can be used for each. This allows the spring members and vibration-proof structure to be constructed simply and inexpensively.

To achieve the above object, the spring member of the present invention is disposed between a structure and a vibrating body disposed on the structure, and supports the vibrating body so that it can be displaced vertically relative to the structure. The spring member comprises: a lower member fixed to the structure; an upper member disposed above and facing the lower member and fixed to the vibrating body; a first spring having a lower end connected to the lower member and an upper end not directly connected to the upper member but positioned below the upper member; a second spring having an upper end connected to the upper member and a lower end not directly connected to the lower member but positioned above the lower member and below the upper end of the first spring; and a rigid member disposed at a height that horizontally overlaps the first spring and the second spring, and having an upper end connected to the upper end of the first spring and a lower end connected to the lower end of the second spring.

In the spring member of the present invention, the first spring and the second spring are arranged in series via a rigid member, which allows the spring stiffness to be reduced without reducing the spring support capacity (yield strength).
Two individual springs (first and second springs) are connected in series via a rigid member and folded to a height where they overlap horizontally. This reduces the axial stiffness of the composite spring by half, and the height of the combined spring member is significantly reduced to less than twice the length of the individual springs, making it compact. As a result, the depth of the recess in the structure where the vibrating body is placed does not become excessive, and the depth of the foundation or other structure does not increase.
The first and second springs do not need to be nested, but can simply be arranged in a plane with a rigid member interposed therebetween, and common springs (such as coil springs or disc springs, the materials of which are readily available and inexpensive) can be used for each spring. This allows the spring members and vibration-proof structure to be constructed simply and inexpensively.

Furthermore, in the spring member according to the present invention, the third springs may be arranged in series at the same height, with the upper ends of the third springs connected to the upper end of one of the adjacent springs and the lower ends connected to the lower end of the other adjacent spring, with the connecting portions between the upper ends of the third springs and the connecting portions between the lower ends of the third springs alternately arranged, and the third spring at one end of the arrangement and adjacent to the first spring may have its upper end connected to the upper end of the first spring, and the third spring at the other end of the arrangement and adjacent to the second spring may have its lower end connected to the lower end of the second spring.

In this invention, multiple individual springs (a first spring, a second spring, and multiple third springs) are lined up in series and folded to a height where they overlap horizontally. As a result, if there are n individual springs, the axial stiffness of the composite spring can be reduced to 1/n, and the height of the combined individual springs can be significantly reduced to less than n times the length of the individual springs, making it more compact.

Furthermore, the spring member according to the present invention may have a guide portion that guides a first connecting portion that connects the first spring and the third spring and a second connecting portion that connects the second spring and the third spring so that they can move vertically relative to the lower member.

With this configuration, the first and second connecting parts are restrained from horizontal displacement or rotation around the vertical axis, but are free to move vertically. As a result, the horizontal movement of the first, second, and third springs is restrained, so the buckling length of the composite spring, which is made up of the first, second, and third springs arranged in series, remains the same as the buckling length of each individual spring, creating a structure in which the buckling strength does not decrease.

Furthermore, in the spring member according to the present invention, the guide portion may have a guide support pillar erected on the lower member, and the guide support pillar may be inserted into a hole formed in the first connecting portion and the second connecting portion, penetrating the vertical direction.

This configuration allows the guide section to be installed easily and in a space-saving manner.

According to the present invention, spring members and vibration-proof structures can be constructed inexpensively with simple structures.

1 is a vertical cross-sectional view showing an example of a vibration-proof structure according to a first embodiment. FIG. 2 is a front view of the spring member according to the first embodiment. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 3 is a cross-sectional view taken along line BB in FIG. 2. 3 is a cross-sectional view taken along line CC in FIG. 2. 3 is a cross-sectional view taken along the line DD in FIG. 2. 10A and 10B are diagrams illustrating the behavior of a spring member. 10A to 10C are diagrams illustrating the behavior of the spring member of the vibration-proof structure according to the second embodiment.

(First embodiment)
A spring member and a vibration-proof structure according to an embodiment of the present invention will be described below with reference to FIGS.
As shown in Figure 1, the vibration-proof structure 1 of this embodiment has a structure 2, a floating floor 3 (vibration body) installed above the structure 2, and a spring member 4 provided between the structure 2 and the floating floor 3.

The vibration isolation structure 1 according to this embodiment is intended to be used in buildings such as large halls, with people and objects standing on the floating floor 3. When the building is used for live music performances, dancing, etc., the vibration isolation structure 1 is configured so that vertical vibrations (so-called vertical vibrations) occur in the floating floor 3 when the floating floor 3 is vibrated by a large number of people bending and stretching to the music on top of the floating floor 3, for example.
If the building is to be used for exhibitions, sporting events, etc., the floating floor 3 may be configured so that it can be used as a fixed floor that does not vibrate vertically.

The structure 2 is, for example, a building foundation, and is constructed of reinforced concrete. In this embodiment, the structure 2 has a recess 21 that opens upward. The structure 2 has a bottom plate portion 22 located below the recess 21, and a side wall portion 23 located to the side of the recess 21 and extending upward from the peripheral edge of the bottom plate portion 22.

The floating floor 3 is formed in a flat plate shape and is placed in the recess 21 of the structure 2 with the plate surface facing horizontally. The floating floor 3 is placed above the bottom plate 22, overlapping it with a gap in between. In this embodiment, the upper surface 31 of the floating floor 3 is positioned so that it is at approximately the same height as the upper end surface 231 of the side wall 23 of the structure 2 when the floating floor 3 is not vibrating vertically.

A plurality of spring members 4 are arranged in parallel at horizontal intervals between the bottom plate portion 22 and the floating floor 3. Each of the spring members 4 is connected to the floating floor 3 and the bottom plate portion 22. The vibration-proof structure 1 is configured so that when the floating floor 3 is vibrated in the vertical direction, the spring members 4 expand and contract, causing the floating floor 3 to vibrate vertically relative to the structure 2. The spring members 4 have the same configuration, and each has the same spring stiffness.

As shown in Figures 2 to 4, the spring member 4 includes a lower plate portion 41 (lower member, see Figures 2 and 3) fixed to the upper surface of the bottom plate portion 22 (see Figure 1), an upper plate portion 42 (upper member, see Figures 2 and 3) fixed to the underside of the floating floor 3 (see Figure 1), a first spring 51 (see Figures 2 and 3), a second spring 52, and a third spring 53 (see Figures 2 and 3) arranged in series between the lower plate portion 41 and the upper plate portion 42, a first connecting portion 61 (see Figure 3) connecting the first spring 51 and the third spring 53, a second connecting portion 62 (see Figure 3) connecting the second spring 52 and the third spring 53, and a guide support 63 (guide portion, see Figures 2 and 3) that supports the first connecting portion 61 and the second connecting portion 62 so that they can move vertically relative to the lower plate portion 41.

3 and 5, the lower plate 41 is a flat plate material with a rectangular surface, and is fixed to the upper surface of the bottom plate 22 with the surface oriented horizontally. An upper plate 43 protruding upward from the lower plate 41 is provided on an edge 41b of the lower plate 41.
3 and 4, the upper plate portion 42 is a flat plate material whose surface is substantially the same rectangular shape as the upper plate portion 42, and is fixed to the underside of the floating floor 3 with the surface oriented horizontally. A lower plate portion 44 that protrudes downward from the upper plate portion 42 is provided on an edge portion 42b of the upper plate portion 42.
The lower plate portion 41 and the upper plate portion 42 are arranged to face each other in the vertical direction and overlap each other when viewed from the vertical direction. The lower plate portion 44 and the upper plate portion 43 are arranged at a height such that they do not come into contact with each other even when the floating floor 3 vibrates vertically relative to the structure 2.

3, the first spring 51 is a spring that extends in the vertical direction. A lower end 51a of the first spring 51 is connected to the lower plate portion 41. An upper end 51b of the first spring 51 is not directly connected to the upper plate portion 42 and is located below the upper plate portion 42.
An upper end 51b of the first spring 51 is connected to the first connecting portion 61. The first connecting portion 61 is located below the upper plate portion 42 and is not directly connected to the upper plate portion 42 or the lower plate portion 41.

The second spring 52 is a spring that extends in the vertical direction. The second spring 52 has the same cross-sectional shape and spring stiffness as the first spring 51. An upper end 52b of the second spring 52 is connected to the upper plate portion 42. A lower end 52a of the second spring 52 is not directly connected to the lower plate portion 41 and is located above the lower plate portion 41.
The lower end 52a of the second spring 52 is connected to the second connecting portion 62. The second connecting portion 62 is located above the lower plate portion 41 and is not directly connected to the upper plate portion 42 or the lower plate portion 41. The second connecting portion 62 is located below the first connecting portion 61. In other words, the lower end 52a of the second spring 52 is located below the upper end 51b of the first spring 51.

The first connecting portion 61 and the second connecting portion 62 have portions that are arranged vertically opposite each other, and each has a portion that is not vertically opposite the other. The first spring 51 and the second spring 52 are arranged in positions where they do not overlap vertically. The first spring 51 is arranged in a position where it does not interfere with the second connecting portion 62. The second spring 52 is arranged in a position where it does not interfere with the first connecting portion 61.

The third spring 53 is a spring that extends in the vertical direction. The third spring 53 has the same cross-sectional shape and spring stiffness as the first spring 51 and the second spring 52. The third spring 53 is disposed between the first connecting portion 61 and the second connecting portion 62. An upper end 53b of the third spring 53 is connected to the first connecting portion 61. A lower end 53a of the third spring 53 is connected to the second connecting portion 62. The third spring 53 is disposed in a position that does not overlap the first spring 51 and the second spring 52 when viewed vertically.
The first spring 51 and the second spring 52 are connected via a first connecting portion 61 , a third spring 53 , and a second connecting portion 62 .

In this embodiment, one spring member 4 is provided with four first springs 51, four second springs 52, and four third springs 53. The four first springs 51 are arranged at intervals in the horizontal direction. The upper ends 51b of each of the four first springs 51 are connected to the same first connecting portion 61. The four second springs 52 are arranged at intervals in the horizontal direction. The lower ends 52a of each of the four second springs 52 are connected to the same second connecting portion 62. The four third springs 53 are arranged at intervals in the horizontal direction. The upper ends 53b of each of the four third springs 53 are connected to the same first connecting portion 61. The lower ends 53a of each of the four third springs 53 are connected to the same second connecting portion 62.

The first connecting portion 61 and the second connecting portion 62 are each a flat plate-shaped member and are arranged with their plate surfaces oriented in a horizontal plane. The first connecting portion 61 and the second connecting portion 62 are movable in the vertical direction relative to the lower plate portion 41 and the upper plate portion 42. The first connecting portion 61 is arranged above the second connecting portion 62. The first connecting portion 61 is arranged on the upper side between the upper plate portion 42 and the lower plate portion 41. The second connecting portion 62 is arranged on the lower side between the upper plate portion 42 and the lower plate portion 41.
An upper end 51 b of the first spring 51 and an upper end 53 b of the third spring 53 are connected to the lower surface of the first connecting portion 61. A lower end 52 a of the second spring 52 and a lower end 53 a of the third spring 53 are connected to the upper surface of the second connecting portion 62.

As shown in Figure 6, the plate surface of the first connecting portion 61 has a cross shape formed by connecting diagonal corners of the plate surfaces of the lower plate portion 41 and the upper plate portion 42 (see Figure 4). The central portion of the first connecting portion 61 when viewed vertically is referred to as a first central portion 611, and four pieces protruding radially from the first central portion 611 are referred to as a first protruding piece 612, a second protruding piece 613, a third protruding piece 614, and a fourth protruding piece 615. The space between the first protruding piece 612 and the second protruding piece 613 is referred to as a first hollow portion 616, the space between the second protruding piece 613 and the third protruding piece 614 is referred to as a second hollow portion 617, the space between the third protruding piece 614 and the fourth protruding piece 615 is referred to as a third hollow portion 618, and the space between the fourth protruding piece 615 and the first protruding piece 612 is referred to as a fourth hollow portion 619.
The first protruding piece 612, the second protruding piece 613, the third protruding piece 614, and the fourth protruding piece 615 are opposed to the corners 41a, 42a of the lower plate portion 41 and the upper plate portion 42, respectively, in the vertical direction.

As shown in FIG. 7 , the plate surface of the second connecting portion 62 has an octagonal shape with the four corners 41a, 42a of the lower plate portion 41 and the upper plate portion 42 each cut off at an angle. The central portion of the second connecting portion 62 when viewed vertically is referred to as the second central portion 621. The edges corresponding to the eight sides of the octagonal plate surface of the second connecting portion 62 are referred to circumferentially as the first to eighth edges 622-629. The first edge 622, the third edge 624, the fifth edge 626, and the seventh edge 628 correspond to the edges of the above-mentioned cut off corners. The second edge 623, the fourth edge 625, the sixth edge 627, and the eighth edge 629 overlap vertically with the edges 41b, 42b of the lower plate portion 41 and the upper plate portion 42.

As described above, the first connecting portion 61 and the second connecting portion 62 have portions that are arranged vertically opposite each other, and each has a portion that is not vertically opposite the other. The first connecting portion 61 shown in Figure 6 and the second connecting portion 62 shown in Figure 7 are arranged as follows.

The first central portion 611 of the first connecting portion 61 and the second central portion 621 of the second connecting portion 62 overlap in the vertical direction.
The tip sides 612a, 613a, 614a, 615a (the sides farther from the first central portion 611) of the first protruding piece 612, the second protruding piece 613, the third protruding piece 614 and the fourth protruding piece 615 of the first connecting portion 61 are positioned outside the first edge portion 622, the third edge portion 624, the fifth edge portion 626 and the seventh edge portion 628 of the second connecting portion 62 when viewed from the vertical direction.
The base end sides 612b, 613b, 614b, 615b (sides closer to the first central portion 611) of the first protruding piece 612, the second protruding piece 613, the third protruding piece 614 and the fourth protruding piece 615 of the first connecting portion 61 are positioned inside the first edge portion 622, the third edge portion 624, the fifth edge portion 626 and the seventh edge portion 628 of the second connecting portion 62 when viewed from the vertical direction.

Portions 623a, 625a, 627a, 629a near the second edge 623, fourth edge 625, sixth edge 627, and eighth edge 629 of the second connecting portion 62 overlap with the first hollow portion 616, second hollow portion 617, third hollow portion 618, and fourth hollow portion 619 on the outside of the first connecting portion 61 when viewed from the top and bottom.
That is, the first connecting portion 61 and the second connecting portion 62 are configured such that the first central portion 611 and the second central portion 621 face each other in the vertical direction, and the base end sides 612b, 613b, 614b, 615b of the first protruding piece 612, the second protruding piece 613, the third protruding piece 614, and the fourth protruding piece 615 of the first connecting portion 61 face each other in the vertical direction with the portions 622a, 624a, 626a, 628a near the first edge portion 622, the third edge portion 624, the fifth edge portion 626, and the seventh edge portion 628 of the second connecting portion 62, respectively.

The four first springs 51 are arranged between the tip ends 612a, 613a, 614a, and 615a of the first protruding piece 612, the second protruding piece 613, the third protruding piece 614, and the fourth protruding piece 615 of the first connecting portion 61 and the four corners 41a of the lower plate portion 41. The lower ends 51a of the four first springs 51 are respectively connected to the four corners 41a of the lower plate portion 41. The upper ends 51b of the four first springs 51 are respectively connected to the tip ends 612a, 613a, 614a, and 615a of the first protruding piece 612, the second protruding piece 613, the third protruding piece 614, and the fourth protruding piece 615 of the first connecting portion 61.

The four second springs 52 are arranged between portions 623a, 625a, 627a, and 629a near the second edge 623, fourth edge 625, sixth edge 627, and eighth edge 629 of the second connecting portion 62, respectively, and portions 42c near the centers of each edge 42b of the upper plate portion 42. The upper ends 52b of the four second springs 52 are respectively connected to portions 42c near the centers of each edge 42b of the upper plate portion 42. The lower ends 52a of the four second springs 52 are respectively connected to portions 623a, 625a, 627a, and 629a near the second edge 623, fourth edge 625, sixth edge 627, and eighth edge 629 of the second connecting portion 62, respectively.

The four third springs 53 are arranged between the base ends 612b, 613b, 614b, and 615b of the first protruding piece 612, the second protruding piece 613, the third protruding piece 614, and the fourth protruding piece 615 of the first connecting part 61, respectively, and the portions 622a, 624a, 626a, and 629a near the first edge 622, the third edge 624, the fifth edge 626, and the seventh edge 628 of the second connecting part 62, respectively. The upper ends 53b of the four third springs 53 are connected to the base ends 612b, 613b, 614b, and 615b of the first protruding piece 612, the second protruding piece 613, the third protruding piece 614, and the fourth protruding piece 615 of the first connecting part 61, respectively. The lower ends 53a of the four third springs 53 are connected to portions 622a, 624a, and 626a near the first edge 622, third edge 624, fifth edge 626, and seventh edge 628 of the second connecting portion 62, respectively.

The first central portion 611 of the first connecting portion 61 and the second central portion 621 of the second connecting portion 62 each have a hole 611a, 621a that penetrates vertically. The guide support 63 is a columnar member fixed to the lower plate portion 41 and extending vertically upward from the lower plate portion 41. The upper end 53b of the guide support 63 is located below the upper plate portion 42. The guide support 63 is inserted through the hole 611a of the first connecting portion 61 and the hole 621a of the second connecting portion 62, penetrating the first connecting portion 61 and the second connecting portion 62. This allows the first connecting portion 61 and the second connecting portion 62 to move vertically along the guide support 63, while horizontal movement is restricted. In other words, the horizontal movement of the first spring 51, the second spring 52, and the third spring 53 is restricted.

The spring member 4 is constructed by arranging a first spring 51, a second spring 52, and a third spring 53, all of which have the same cross section and spring stiffness, in series, and then arranging multiple composite springs in parallel, each of which consists of these three springs arranged in series. This allows for the construction of a compact spring member 4 with low spring stiffness.

If the spring stiffness of the first spring 51 is _k1 , the spring stiffness of the second spring 52 is _k2 , and the spring stiffness of the third spring 53 is _k3 , then the combined spring stiffness k is expressed by the following formula: Because the springs are connected in series, the force acting on each spring is the same, and each displacement is inversely proportional to the spring stiffness.

If the spring stiffness k ₁ of the first spring 51, the spring stiffness k ₂ of the second spring 52, and the spring stiffness k ₃ of the third spring 53 are all the same (k ₁ =k ₂ =k ₃ =k ₀ ), then k=k ₀ /3.
The force acting on each spring is the same, and the displacement is the same.

When n springs with stiffness _k0 are connected in series, the stiffness of the composite spring becomes _k0 /n, which is 1/n of that of a single spring, and is the same stiffness as when the length of a single spring is n times longer. Therefore, if n springs are arranged in a folded form at the same height, spring member 4, which is a combination of single springs of length L, will have a stiffness of _k0 /n while maintaining its length as L. If the displacement of each of first spring 51, second spring 52, and third spring 53 is a, the total stroke is 3a.
FIG. 8 shows the case where a compressive force is applied when the number of springs is n=3 as in this embodiment.
In this embodiment, when a compressive force acts on the spring member 4, a compressive force acts on the first spring 51 and the second spring 52 on both sides of the three springs, and a tensile force acts on the third spring 53 in the center.
Since the floating floor 3 is vibrated vertically across its entire surface, the vibration force acts on the center of gravity of the floating floor 3.

In the spring member 4 of this embodiment, four composite springs are arranged in parallel, each consisting of a first spring 51, a second spring 52, and a third spring 53 arranged in series. If the yield strength of a single spring is _F0 and the stiffness is _k0 , then the yield strength of a composite spring formed by combining 4 x 3 = 12 of these is _4F0 and the stiffness is _4k0 /3. In other words, compared to four parallel individual springs, the yield strength is the same but the stiffness is reduced to one-third. This is the same as reducing the spring length to one-third.

Next, the functions and effects of the spring member 4 and the vibration-proof structure 1 according to the present embodiment will be described.
The spring member 4 according to the present embodiment has the first spring 51, the second spring 52, and the third spring 53, which have the same cross section and the same spring stiffness, arranged in series. This allows the spring stiffness to be reduced without reducing the spring support capacity (proof stress).
Multiple (n) simple springs are connected in series and folded to the same height, and a composite spring consisting of multiple simple springs connected in series is arranged in parallel in a plane. This reduces the axial stiffness of the composite spring to 1/n, and the height of the spring member 4 made up of combined simple springs is significantly reduced to less than n times the length of the simple springs, making it compact. As a result, the depth of the recess 21 in the structure 2 where the floating floor 3 is placed does not become excessive, and the depth of the structure 2, such as the foundation, does not increase.
The first spring 51, the second spring 52, and the third spring 53 do not need to be nested, but can simply be arranged in a plane, and common springs with the same cross-sectional shape (for example, coil springs or disc springs, the materials of which are readily available and inexpensive) can be used for each of them. This allows the spring member 4 and the vibration-proof structure 1 to be constructed simply and inexpensively.
Since spring prices are generally proportional to length, there is not much difference in spring cost whether multiple short springs are lined up next to each other or a single long spring is produced.
Furthermore, if the spring member 4 is manufactured in a factory by combining unit springs, it can be installed on site in the same way as a general spring member 4, making installation easy.

The spring member 4 in the above embodiment is provided with guide struts 63 that guide the first connecting portion 61 and the second connecting portion 62 so that they can move vertically relative to the lower plate portion 41. As a result, the horizontal displacement and rotation around the vertical axis of the first connecting portion 61 and the second connecting portion 62 are restrained, but they are free to move vertically. As a result, the horizontal movement of the first spring 51, the second spring 52, and the third spring 53 is restrained, so that the buckling length of the composite spring in which the first spring 51, the second spring 52, and the third spring 53 are arranged in series remains the same as the buckling length of each individual spring, and a structure can be achieved in which the buckling strength is not reduced.
The guide pillar 63 is configured to be inserted through holes 611 a and 621 a formed in the first connecting portion 61 and the second connecting portion 62 , the holes 611 a and 621 a passing through in the vertical direction.
By adopting such a configuration, the guide portion can be provided easily and in a space-saving manner.

By displacing the springs with a preload to prevent most of the deflection (sinking amount) caused by the floating floor 3's own weight and preventing them from returning to their original position, the springs will not displace below the preload load, and the height of the spring member 4, which is made up of individual springs, can be made significantly smaller than when no preload is applied.

The first connecting portion 61 is cross-shaped, and the second connecting portion 62 is octagonal, with portions of the first connecting portion 61 and the second connecting portion 62 that do not overlap in the vertical direction. This eliminates the need for through holes in the first connecting portion 61 and the second connecting portion 62 to install the first spring 51 and the second spring 52.

Second Embodiment
Next, another embodiment will be described based on the accompanying drawings. Components and parts that are the same as or similar to those in the first embodiment described above will be designated by the same reference numerals, and their description will be omitted. Configurations that differ from the embodiment will be described.
9, in a spring member 4B and vibration-proof structure 1B according to the second embodiment, a rigid member 54 is provided in place of the third spring 53 of the spring member 4 of the second embodiment. The rigid member 54 is a rod-shaped member that extends vertically, with an upper end 54b connected to the first connecting portion 61 and a lower end 54a fixed to the second connecting portion 62. If the displacement of each of the first spring 51 and the second spring 52 is a, then the total stroke is 2a.
In this case, when a compressive force acts on the spring member 4, the compressive force acts on the first spring 51 and the second spring 52 on both sides.

In the second embodiment, the spring stiffness of the first spring 51 is k ₁ , the spring stiffness of the second spring 52 is k ₂ , and the stiffness of the rigid member 54 is k ₃ .
If the spring stiffness _k1 of the first spring 51 and the spring stiffness _k2 of the second spring 52 are the same ( _k1 = _k2 = _k0 ) and the rigid member 54 is rigid ( _k3 = ∞), then k = _k0 /2 is obtained from the equation described in paragraph 0046 above.
In the second embodiment, the force acting on each spring is the same, and the displacements of the first spring and the second spring are the same (inverse ratio of spring stiffness).

In the spring member 4B according to the second embodiment, the first spring 51 and the second spring 52 have the same cross section and the same spring stiffness, and are arranged in series via the rigid member 54. The rigid member 54 has a stiffness that prevents it from expanding and contracting in the vertical direction. This allows the spring stiffness to be reduced without reducing the spring support capacity (proof stress).
Two individual springs are connected in series and folded to the same height, and a composite spring consisting of multiple individual springs connected in series is arranged in parallel in a plane. This reduces the axial stiffness of the composite spring by half, and the height of the combined individual springs is significantly reduced to less than twice the length of the individual springs, making it compact. As a result, the depth of the recess 21 in the structure 2 where the floating floor 3 is placed is not excessive, and the depth of the structure 2, such as the foundation, is not increased.
The first spring 51 and the second spring 52 do not need to be arranged in a nested manner, but can simply be arranged in a plane via the rigid member 54. In addition, since each spring can be made of a common spring with the same cross-sectional shape (for example, a coil spring or a disc spring, the materials of which are easy to obtain and inexpensive), the spring member 4 and the vibration-proof structure 1 can be constructed inexpensively with a simple structure.

Although the embodiments of the spring member and vibration-proof structure according to the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the invention.
For example, in the spring member 4 according to the first embodiment described above, the first spring 51, the second spring 52, and the third spring 53 have the same cross section and the same spring rigidity and are arranged in series, but the cross section, shape, and spring rigidity of each of the first spring 51, the second spring 52, and the third spring 53 may be different.
In the spring member 4B according to the second embodiment described above, the first spring 51 and the second spring 52 have the same cross section and the same spring rigidity and are arranged in series via the rigid member 54, but the cross section, shape, and spring rigidity of each of the first spring 51 and the second spring 52 may be different.

In the above embodiment, the spring member 4 is provided with a guide support 63 that guides the first connecting portion 61 connecting the first spring 51 and the third spring 53 and the second connecting portion 62 connecting the second spring 52 and the third spring 53 so that they can move vertically relative to the lower plate portion 41. The spring member 4 may not be provided with a guide portion, or may be provided with a guide portion of a form other than the above. For example, a rail member that guides the edges of the first member and the second member vertically may be fixed to the lower plate portion 41.

In the above embodiment, the first connecting portion 61 is cross-shaped, the second connecting portion 62 is octagonal, and each of the first connecting portion 61 and the second connecting portion 62 has a portion that does not overlap with the other in the vertical direction, to which the first spring 51 and the second spring 52 are connected. Alternatively, the first connecting portion 61 and the second connecting portion 62 may have the same shape without having a portion that does not overlap with the other in the vertical direction, with a hole formed in the first connecting portion 61 through which the second spring 52 passes, and a hole formed in the second connecting portion 62 through which the second spring 52 passes.

In the first embodiment described above, one third spring 53 is provided between the first spring 51 and the second spring 52, which are arranged in series. However, a plurality of third springs 53 may be provided in series between the first spring 51 and the second spring 52, which are also arranged in series. In such a case, the plurality of third springs 53 are arranged at the same height, and the connecting portions between the lower ends 53a and the connecting portions between the upper ends 53b are arranged alternately, and the plurality of third springs 53 are installed so as to be folded at each connecting portion.
If the total number of first springs 51, second springs 52, and multiple third springs 53 is n, the axial stiffness of the composite spring in which these springs are arranged in series can be reduced to 1/n, and the height of the spring member 4 made up of combined individual springs can be significantly reduced to less than n times the length of the individual springs, making it compact.

In the second embodiment described above, a rigid member 54 is provided between the first spring 51 and the second spring 52, which are arranged in series. Alternatively, a single or multiple rigid member 54 and springs having the same rigidity as the first spring 51 and the second spring 52 may be provided alternately between the first spring 51 and the second spring 52, which are also arranged in series. In such a case, the spring provided between the first spring 51 and the second spring 52 is arranged so that a compressive or tensile force acts on the first spring 51 and the second spring 52 simultaneously. For example, the springs are arranged in series in the following order: first spring 51, rigid member 54, spring, rigid member 54, ... spring, rigid member 54, second spring 52. In such cases, the springs and rigid members 54 are also positioned at the same height, with the connecting portions between the lower ends of the springs and rigid members 54 and the connecting portions between the upper ends of the springs and rigid members 54 alternately arranged, and the springs and rigid members 54 are positioned so that they fold at each connecting portion.

In the above embodiment, four each of the first springs 51, second springs 52, and third springs 53 are provided in one spring member 4, and four composite springs, each of which is formed by serially arranging the first springs 51, second springs 52, and third springs 53, are arranged in parallel in the spring member 4. The numbers of the first springs 51, second springs 52, and third springs 53 provided in one spring member 4, i.e., the number of composite springs, may be set as appropriate.
In the second embodiment, too, the number of first springs 51, second springs 52 and rigid members 54 provided in one spring member 4B, i.e., the number of composite springs arranged in series of first springs 51, second springs 52 and rigid members 54, may be set appropriately.

In the above embodiment, the spring member 4 and vibration-proof structure 1 are applied to a building facility such as a live music hall with a floating floor 3, but the spring member 4 may also be added to the foundation (structure 2) of a machine (vibrating body) that generates vibrations to suppress vibration damage.

1, 1B Vibration isolation structure 2 Structure 3 Floating floor (vibration body)
4, 4B Spring member 41 Lower plate portion (lower member)
42 Upper plate portion (upper member)
51 First spring 51a Lower end 51b Upper end 52 Second spring 52a Lower end 52b Upper end 53 Third spring 53a Lower end 53b Upper end 54 Rigid member 54a Lower end 54b Upper end 61 First connecting portion 62 Second connecting portion 63 Guide support (guide portion)
611a Hole 621a Hole

Claims (5)

A spring member provided between a structure and a vibrating body provided on the structure, the spring member supporting the vibrating body so as to be displaceable in a vertical direction relative to the structure,
a lower member fixed to the structure;
an upper member disposed above and facing the lower member and fixed to the vibrating body;
a first spring that is expandable and contractible in the vertical direction, has a lower end connected to the lower member, and an upper end that is not directly connected to the upper member and is positioned below the upper member;
a second spring that is expandable in the vertical direction, has an upper end connected to the upper member, and a lower end that is not directly connected to the lower member, and is positioned above the lower member and below the upper end of the first spring;
a third spring that is vertically expandable and contractible, that is positioned at a height that overlaps horizontally with the first spring and the second spring, and that has an upper end connected to the upper end of the first spring and a lower end connected to the lower end of the second spring. The third spring is provided in plurality ,
the third springs are arranged such that the upper ends of the third springs are connected to the upper ends of the springs adjacent to one another and the lower ends of the third springs are connected to the lower ends of the springs adjacent to the other, and the connecting portions between the upper ends of the third springs and the connecting portions between the lower ends of the third springs are arranged alternately;
2. The spring member according to claim 1, wherein the third spring located at one end of the array and adjacent to the first spring has its upper end connected to the upper end of the first spring, and the third spring located at the other end of the array and adjacent to the second spring has its lower end connected to the lower end of the second spring. The spring member according to claim 1 or 2, further comprising a guide portion that guides a first connecting portion connecting the first spring and the third spring and a second connecting portion connecting the second spring and the third spring so that they can move vertically relative to the lower member. The guide portion has a guide post that stands on the lower member,
The spring member according to claim 3 , wherein the guide support is inserted through a hole formed in the first connecting portion and the second connecting portion and passing through in the vertical direction. A vibration-proof structure, comprising: a spring member according to claim 1 provided between the structure and the vibrating body.