BASE ISOLATION SUPPORTING DEVICE

Abstract

A base isolation supporting device 1 includes a support 8 which is adapted to be affixed to an outer casing 4 of a fixture 3 to be supported on a floor 2, so as to receive the load, acting in a vertical direction V, of the fixture 3, and which has a cross-sectionally circular arc-shaped convex outer surface 7; and a rotating body 13 which, at a cross-sectionally circular arc-shaped outer surface 9 thereof, is adapted to be brought into contact with the cross-sectionally circular arc-shaped convex outer surface 7 of the support 8 slidably and rotatably in an R direction about a center O1, while, at a cross-sectionally circular arc-shaped convex outer surface 11 thereof, coming into contact with a flat surface 10 of the floor 2 rollably about the center O1, so as to receive together with the support 8 the load, acting in the vertical direction V, of the fixture 3 via the support 8.

Claims

1. A base isolation supporting device comprising: a support which is adapted to be affixed to one of a foundation or a base and a base isolation support object so as to receive a load of the base isolation support object to be supported on the foundation or the base, and which has a cross-sectionally circular arc-shaped outer surface; and a rotating body which has a cross-sectionally circular arc-shaped outer surface with a shape complementary to the cross-sectionally circular arc-shaped outer surface of the support, and which, at the cross-sectionally circular arc-shaped outer surface with the shape complementary to the cross-sectionally circular arc-shaped outer surface of the support, is adapted to be brought into slidable contact with the cross-sectionally circular arc-shaped outer surface of the support, while, at a cross-sectionally circular arc-shaped convex outer surface thereof, coming into rollable contact with a flat surface of another one of the foundation or the base and the base isolation support object, so as to receive the load of the base isolation support object together with the support, wherein the cross-sectionally circular arc-shaped convex outer surface of the rotating body has a greater radius of curvature than a radius of curvature of the cross-sectionally circular arc-shaped outer surface of the rotating body, and, in a stationary state, a center of curvature of the cross-sectionally circular arc-shaped convex outer surface of the rotating body is positioned eccentrically with respect to a center of curvature of the cross-sectionally circular arc-shaped outer surface of the rotating body toward a side of one of the foundation or the base and the base isolation support object in a vertical direction.

2. The base isolation supporting device according to claim 1, wherein the cross-sectionally circular arc-shaped outer surface of the support is a cross-sectionally circular arc-shaped convex surface, and the cross-sectionally circular arc-shaped outer surface of the rotating body is a cross-sectionally circular arc-shaped concave surface.

3. The base isolation supporting device according to claim 1, wherein the cross-sectionally circular arc-shaped outer surface of the support is a cross-sectionally circular arc-shaped concave surface, and the cross-sectionally circular arc-shaped outer surface of the rotating body is a cross-sectionally circular arc-shaped convex surface.

4. The base isolation supporting device according to claim 1, wherein the cross-sectionally circular arc-shaped outer surface of the support and the cross-sectionally circular arc-shaped outer surface and the cross-sectionally circular arc-shaped convex outer surface of the rotating body are each constituted by a portion of a cylindrical surface.

5. The base isolation supporting device according to claim 1, wherein the cross-sectionally circular arc-shaped outer surface of the support and the cross-sectionally circular arc-shaped outer surface and the cross-sectionally circular arc-shaped convex outer surface of the rotating body are each constituted by a portion of a spherical surface.

6. The base isolation supporting device according to claim 1, wherein the rotating body is rotatable about a center of curvature of the cross-sectionally circular arc-shaped outer surface of the support.

7. The base isolation supporting device according to claim 6, wherein, in the stationary state, the center of curvature of the cross-sectionally circular arc-shaped outer surface of the support and the center of curvature of the cross-sectionally circular arc-shaped convex outer surface of the rotating body are positioned on an identical vertical line.

8. The base isolation supporting device according to claim 1, wherein the rotating body includes a rigid body having a cross-sectionally circular arc-shaped outer surface and an elastic body secured to the rigid body and having a cross-sectionally circular arc-shaped convex outer surface.

9. The base isolation supporting device according to claim 1, wherein the rotating body includes an elastic body having a cross-sectionally circular arc-shaped outer surface and a rigid body secured to the elastic body and having a cross-sectionally circular arc-shaped convex outer surface.

10. The base isolation supporting device according to claim 1, wherein the support is adapted to be affixed to the base isolation support object, and the rotating body at the cross-sectionally circular arc-shaped convex outer surface is adapted to be brought into rollable contact with the flat surface of the foundation or the base, the center of curvature of the cross-sectionally circular arc-shaped convex outer surface of the rotating body being positioned eccentrically upwardly in the vertical direction with respect to the center of curvature of the cross-sectionally circular arc-shaped outer surface of the rotating body.

11. The base isolation supporting device according to claim 1, wherein the support is adapted to be affixed to the foundation or the base, and the rotating body at the cross-sectionally circular arc-shaped convex outer surface is adapted to be brought into rollable contact with the flat surface of the base isolation support object, the center of curvature of the cross-sectionally circular arc-shaped convex outer surface of the rotating body being positioned eccentrically downwardly in the vertical direction with respect to the center of curvature of the cross-sectionally circular arc-shaped outer surface of the rotating body.

12. The base isolation supporting device according to claim 1, further comprising a disengagement prevention mechanism for preventing the disengagement of the rotating body from the support by inhibiting the rotation of the rotating body more than a fixed degree as the rotating body collides against the disengagement prevention mechanism in the rotation of the rotating body about the center of curvature of the cross-sectionally circular arc-shaped outer surface of the support.

13. The base isolation supporting device according to claim 12, wherein the disengagement prevention mechanism has an enclosure body which is mounted to the support and encloses the rotating body, and the enclosure body has an inner surface which the rotating body contacts in the rotation of the rotating body more than a fixed degree about the center of curvature of the cross-sectionally circular arc-shaped outer surface of the support.

14. A base isolation supporting device comprising: a support which is adapted to be affixed to one of a foundation or a base and a base isolation support object so as to receive a load of the base isolation support object to be supported on the foundation or the base, and which has a first cross-sectionally circular arc-shaped convex outer surface; and a rotating body which has a cross-sectionally circular arc-shaped concave outer surface which is brought into slidable contact with the first cross-sectionally circular arc-shaped convex outer surface of the support, and which, at a second cross-sectionally circular arc-shaped convex outer surface thereof, is adapted to be brought into rollable contact with a flat surface of another one of the foundation or the base and the base isolation support object, so as to receive the load of the base isolation support object together with the support, wherein the rotating body is rotatable with respect to the support about a center of curvature of the cross-sectionally circular arc-shaped concave outer surface of the rotating body, the second cross-sectionally circular arc-shaped convex outer surface of the rotating body has a greater radius of curvature than a radius of curvature of the cross-sectionally circular arc-shaped concave outer surface of the rotating body, and, in a stationary state, a center of curvature of the second cross-sectionally circular arc-shaped convex outer surface of the rotating body is positioned eccentrically with respect to the center of curvature of the cross-sectionally circular arc-shaped concave outer surface of the rotating body toward a side of one of the foundation or the base and the base isolation support object in a vertical direction.

15. The base isolation supporting device according to claim 14, wherein the first cross-sectionally circular arc-shaped convex outer surface of the support and the cross-sectionally circular arc-shaped concave outer surface of the rotating body are each constituted by a portion of a cylindrical surface.

16. The base isolation supporting device according to claim 14, wherein the first cross-sectionally circular arc-shaped convex outer surface of the support and the cross-sectionally circular arc-shaped concave outer surface of the rotating body are each constituted by a portion of a spherical surface.

17. The base isolation supporting device according to claim 14, wherein the support includes a main body portion adapted to be affixed to one of the foundation or the base and the base isolation support object and a sliding portion formed integrally with the main body portion in such a manner as to be disposed between the main body portion and the rotating body and having the first cross-sectionally circular arc-shaped convex outer surface.

18. The base isolation supporting device according to claim 14, wherein the first cross-sectionally circular arc-shaped convex outer surface of the support has an identical radius of curvature to the radius of curvature of the cross-sectionally circular arc-shaped concave outer surface of the rotating body.

19. The base isolation supporting device according to claim 18, wherein centers of curvature of the first cross-sectionally circular arc-shaped convex outer surface of the support and the cross-sectionally circular arc-shaped concave outer surface of the rotating body are positioned at an identical position.

20. The base isolation supporting device according to claim 14, wherein the first cross-sectionally circular arc-shaped convex outer surface of the support has a smaller radius of curvature than the radius of curvature of the cross-sectionally circular arc-shaped concave outer surface of the rotating body.

21. The base isolation supporting device according to claim 14, wherein, in the stationary state, the centers of curvature of the cross-sectionally circular arc-shaped concave outer surface and the second cross-sectionally circular arc-shaped convex outer surface of the rotating body are positioned on an identical vertical line.

22. The base isolation supporting device according to claim 14, wherein, in the stationary state, the centers of curvature of the first cross-sectionally circular arc-shaped convex outer surface of the support and the cross-sectionally circular arc-shaped concave outer surface and the second cross-sectionally circular arc-shaped convex outer surface of the rotating body are positioned on an identical vertical line.

23. The base isolation supporting device according to claim 14, wherein the rotating body includes a rigid body having a cross-sectionally circular arc-shaped concave outer surface and an elastic body secured to the rigid body and having the second cross-sectionally circular arc-shaped convex outer surface.

24. The base isolation supporting device according to claim 14, wherein the rotating body includes an elastic body having a cross-sectionally circular arc-shaped concave outer surface and a rigid body secured to the elastic body and having the second cross-sectionally circular arc-shaped convex outer surface.

25. The base isolation supporting device according to claim 14, wherein the support is adapted to be affixed to the base isolation support object, and the rotating body at the second cross-sectionally circular arc-shaped convex outer surface is adapted to be brought into rollable contact with the flat surface of the foundation or the base, the center of curvature of the second cross-sectionally circular arc-shaped convex outer surface of the rotating body being positioned eccentrically upwardly in the vertical direction with respect to the center of curvature of the cross-sectionally circular arc-shaped concave outer surface of the rotating body.

26. The base isolation supporting device according to claim 14, wherein the support is adapted to be affixed to the foundation or the base, and the rotating body at the second cross-sectionally circular arc-shaped convex outer surface is adapted to be brought into rotatable contact with the flat surface of the base isolation support object, the center of curvature of the second cross-sectionally circular arc-shaped convex outer surface of the rotating body being positioned eccentrically downwardly in the vertical direction with respect to the center of curvature of the cross-sectionally circular arc-shaped concave outer surface of the rotating body.

27. The base isolation supporting device according to any claim 14, further comprising a disengagement prevention mechanism for preventing the disengagement of the rotating body from the support by inhibiting the rotation of the rotating body more than a fixed degree as the rotating body collides against the disengagement prevention mechanism in the rotation of the rotating body about the center of curvature of the cross-sectionally circular arc-shaped concave outer surface of the rotating body with respect to the support.

28. The base isolation supporting device according to claim 27, wherein the disengagement prevention mechanism has an enclosure body which is mounted to the support and encloses the rotating body, and the enclosure body has an inner surface which the rotating body contacts in the rotation of the rotating body more than a fixed degree about the center of curvature of the cross-sectionally circular arc-shaped concave outer surface of the rotating body with respect to the support.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is an explanatory side elevational view of a preferred embodiment in accordance with the present invention;

[0029] FIG. 2 is an explanatory view of the operation of the embodiment shown in FIG. 1;

[0030] FIG. 3 is an explanatory side elevational view of another preferred embodiment in accordance with the present invention;

[0031] FIG. 4 is an explanatory side elevational view of still another preferred embodiment in accordance with the present invention;

[0032] FIG. 5 is an explanatory view of the operation of the embodiment shown in FIG. 4;

[0033] FIG. 6 is an explanatory side elevational view of a further preferred embodiment in accordance with the present invention;

[0034] FIG. 7 is an explanatory view of the operation of the embodiment shown in FIG. 6;

[0035] FIG. 8 is an explanatory side elevational view of a still further preferred embodiment in accordance with the present invention;

[0036] FIG. 9 is an explanatory side elevational view of a further preferred embodiment in accordance with the present invention;

[0037] FIG. 10 is an explanatory side elevational view of a further preferred embodiment in accordance with the present invention; and

[0038] FIG. 11 is an explanatory view of the operation of the embodiment shown in FIG. 10.

MODE FOR CARRYING OUT THE INVENTION

[0039] Next, a more detailed description will be given of the invention on the basis of the preferred embodiments illustrated in the drawings. It should be noted that the invention is not limited to these embodiments.

[0040] In FIG. 1, a base isolation supporting device 1 in accordance with this embodiment includes a support 8 which is adapted to be affixed by a screw 5 or the like through a fitting 6 to a lower portion of an outer casing 4 of a fixture 3, such as a display rack of a store, i.e., a base isolation support object to be supported on a floor 2 of the store, i.e., a foundation or a base, in order to receive the load, acting in a vertical direction V, of the fixture 3, the support 8 having a cross-sectionally circular arc-shaped convex outer surface 7 with a center O1, i.e., a center of curvature thereof; and a rotating body 12 which has a cross-sectionally circular arc-shaped concave outer surface 9 with a shape complementary to the cross-sectionally circular arc-shaped convex outer surface 7 of the support 8 and a center of curvature at the same position as the center O1, and which, at the cross-sectionally circular arc-shaped concave outer surface 9, is adapted to be brought into contact with the cross-sectionally circular arc-shaped convex outer surface 7 of the support 8 slidably and rotatably in an R direction about the center O1, while, at a cross-sectionally circular arc-shaped convex outer surface 11 having a center O2, i.e., a center of curvature thereof, coming into contact with a flat surface 10 of the floor 2 rotatably in the R direction about the center O2, namely, coming into contact therewith rollably about the center O2, so as to receive together with the support 8 the load, acting in the vertical direction V, of the fixture 3 via the support 8.

[0041] The support 8 has a columnar main body 23 with a threaded portion 21 provided at an upper portion thereof and a constricted portion 22 provided at a lower portion thereof and a partially spherical portion 24 provided integrally on the constricted portion 22 of the main body 23, and the support 8 is fixed to the fitting 6 at the threaded portion 21 positionally adjustably in the vertical direction V by a pair of nuts 25 which are threadedly engaged with the threaded portion 21. The cross-sectionally circular arc-shaped convex outer surface 7 is constituted by a partially spherical convex surface 26 of the partially spherical portion 24 as a portion of a spherical surface.

[0042] The rotating body 12 includes the cross-sectionally circular arc-shaped concave outer surface 9 constituted by a partially spherical concave surface 31 as a portion of a spherical surface, the cross-sectionally circular arc-shaped convex outer surface 11 constituted by a partially spherical convex surface 32 as a portion of a spherical surface, and a truncated conical outer surface or a truncated polygonal conical outer surface including a truncated quadrangular conical outer surface or the like, which is continuously connected to the cross-sectionally circular arc-shaped concave outer surface 9 on one side and to the cross-sectionally circular arc-shaped convex outer surface 11 on the other side, i.e., a truncated conical outer surface 33 in this embodiment. The rotating body 12 is rotatable with respect to the cross-sectionally circular arc-shaped convex outer surface 7 of the support 8 in the R direction about the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 7 of the support 8 and is also the center of curvature of the cross-sectionally circular arc-shaped concave outer surface 9 of the rotating body 12. In a stationary state (the state shown in FIG. 1) of the base isolation supporting device 1, the center O2, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 11 of the rotating body 12, is positioned eccentrically with respect to the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped concave outer surface 9 of the rotating body 12, upwardly toward the fixture 3 side in the vertical direction V with an amount of eccentricity δ. In the stationary state of the base isolation supporting device 1, the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 7 of the support 8, and the center O2, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 11 of the rotating body 12, are positioned on an identical vertical line 35. In the stationary state of the base isolation supporting device 1, the cross-sectionally circular arc-shaped convex outer surface 11 of the rotating body 12 has a radius of curvature r2 which is greater than a distance d between the center O1 and a position P where the cross-sectionally circular arc-shaped convex outer surface 11 comes into contact with the flat surface 10 of the floor 2, and hence the amount of eccentricity δ is r2−d.

[0043] In the case where a tremor in a horizontal direction H due to an earthquake is not applied to the floor 2, each of a plurality of, at least three, base isolation supporting devices 1 disposed at the lower portion of the outer casing 4 of the fixture 3 is in the stationary state shown in FIG. 1, and supports the fixture 3 by sharing the load of the fixture 3 on the floor 2. When a tremor in the horizontal direction H due to an earthquake is applied to the floor 2, the rotating body 12 of each base isolation supporting device 1 rollingly rotates on the flat surface 10 of the floor 2 in the R direction about the center O1 with respect to the partially spherical portion 24, as shown in FIG. 2. By virtue of this rotation, each base isolation supporting device 1 prevents the transmission to the fixture 3 of the tremor in the horizontal direction H applied to the floor 2, thereby supporting the fixture 3 in a base-isolated manner. Meanwhile, a return moment M=W.Math.δ.Math.sin θ (where W is the load applied to the rotating body 12; δ is the amount of eccentricity δ=(r2−d); and θ is the angle of rotation of the rotating body 12) for returning to the stationary state occurs, at each rotated position of the rotating body 12, to the rotating body 12 which is adapted to lift the fixture 3 in the vertical direction V together with its rotation in the R direction because of the difference between the distance d and the radius of curvature r2 of the cross-sectionally circular arc-shaped convex outer surface 11 ascribable to the amount of eccentricity between the center O1 and the center O2. By virtue of this return moment M, the rotating body 12 which undergoes so-called pendular movement having a period T is returned to its rotational position in the stationary state upon the convergence of the pendular movement due to the dissipation of vibrational energy attributable to the sliding friction of the cross-sectionally circular arc-shaped concave outer surface 9 with respect to the cross-sectionally circular arc-shaped convex outer surface 7 as well as the rolling friction of the rotating body 12 with respect to the flat surface 10 of the floor 2 after the extinction of the tremor of the floor 2 in the horizontal direction H due to the earthquake, to thereby return the fixture 3 to its original position persisting prior to the earthquake tremor.

[0044] The period T of the pendular movement of the rotating body 12 is expressed by the formula (1), and in the case where θ is small, θ/sin θ≈1, with the result that the period T is expressed by the formula (2), and the smaller the amount of eccentricity δ(=r2−d), which is the difference between the distance d and the radius of curvature r2 of the cross-sectionally circular arc-shaped convex outer surface 11, the longer the period T becomes, whereas, to the contrary, the greater the amount of eccentricity δ (=r2−d), the shorter the period T becomes.

[00001]$\begin{array}{cc}\left[\mathrm{Mathematical}.Math..Math.\mathrm{Formula}.Math..Math.1\right].Math.& \\ T=2.Math.\pi .Math.\sqrt{\frac{1}{g}}.Math.\left(\frac{r_2}{\sqrt{\delta }}\right).Math.\sqrt{\frac{\theta }{\sin .Math..Math.\theta }}& \left(1\right)\end{array}$

where, g is the acceleration of gravity.

[00002]$\begin{array}{cc}\left[\mathrm{Mathematical}.Math..Math.\mathrm{Formula}.Math..Math.2\right].Math.& \\ T\approx 2.Math.\pi .Math.\sqrt{\frac{1}{g}}.Math.\left(\frac{r_2}{\sqrt{\delta }}\right)& \left(2\right)\end{array}$

[0045] With above-described base isolation supporting device 1, the rotating body 12 at the cross-sectionally circular arc-shaped convex outer surface 11 thereof is adapted to be brought into contact with the flat surface 10 of the floor 2 rollably and rotatably, and, in the stationary state, the center O2, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 11, is offset from the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped concave outer surface 9, upwardly in the vertical direction V with the amount of eccentricity δ, with the result that the base isolation supporting device 1 can be installed by using as it is the flat surface 10 of the floor 2. Moreover, since the period T of the pendular movement of the rotating body 12 can be determined by the amount of eccentricity δ which is the difference between the distance d and the radius of curvature r2 of the cross-sectionally circular arc-shaped convex outer surface 11, it is possible to easily attain a long period. Moreover, since the cross-sectionally circular arc-shaped convex outer surface 7 is constituted by the partially spherical convex surface 26, the cross-sectionally circular arc-shaped concave outer surface 9 is constituted by the partially spherical concave surface 31, and the cross-sectionally circular arc-shaped convex outer surface 11 is constituted by the partially spherical convex surface 32, namely, since the respective surfaces are constituted by spherical surfaces, the fixture 3 can be supported in a base-isolated manner with respect to the tremors of an earthquake in all directions in the horizontal direction H. In addition, since the position for mounting the support 8 to the fitting 6 is adapted to be adjustable by means of the threaded portion 21 and the nuts 25, the fixture 3 can be supported in a base-isolated manner at an arbitrary position in the vertical direction V.

[0046] Incidentally, with the base isolation supporting device 1 shown in FIG. 1, the rotating body 12 is formed of a one-piece body constituted by a rigid body. Alternatively, however, as shown in FIG. 3, the rotating body 12 may include a rigid body 42 having the cross-sectionally circular arc-shaped concave outer surface 9, the truncated conical outer surface 33, and a partially spherical convex surface 41, as well as a natural rubber-made elastic body 43 secured to the partially spherical convex surface 41 of the rigid body 42 by vulcanization bonding and having the cross-sectionally circular arc-shaped convex outer surface 11. If the rotating body 12 is thus provided with the elastic body 43 as a coating layer for the rigid body 42, the fixture 3 can be supported in a base-isolated manner with respect to the tremors of an earthquake in all directions in the horizontal direction H, and, by virtue of the elastic deformation of the elastic body 43, the fixture 3 can be supported in a base-isolated manner with respect to the tremors of an earthquake in the vertical direction V applied to the floor 2, thereby making it possible to protect the fixture 3 itself and an article inside the fixture 3 as well. In addition, it becomes possible to obtain trigger action by the flattening of the cross-sectionally circular arc-shaped convex outer surface 11 due to the depression, caused by partial elastic deformation, of that portion of the elastic body 43 which receives the load in the vertical direction V in the stationary state.

[0047] In the base isolation supporting devices 1 shown in FIGS. 1 and 3, the possibility of the rotating body 12 coming off the support 8 occurs in the tremor of an earthquake accompanying a large rotational angle θ of the rotating body 12. However, as shown in FIG. 4, the base isolation supporting device 1 may further have a disengagement prevention mechanism 51 for preventing the disengagement of the rotating body 12 from the support 8 by inhibiting the rotation of the rotating body 12 more than a fixed degree as the rotating body 12 collides against the disengagement prevention mechanism 51 in the rotation in the R direction of the rotating body 12 about the center O1 which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 7 of the support 8. The disengagement prevention mechanism 51 has an enclosure body 52 which is mounted to the support 8 and encloses the rotating body 12.

[0048] The enclosure body 52 includes a disk-shaped ceiling portion 55 secured to the threaded portion 21 of the support 8 by being sandwiched between the fitting 6 and the nuts 25; a cylindrical portion 56 formed integrally at an upper end thereof with an outer peripheral edge of the ceiling portion 55 in such a manner as to surround the rotating body 12 from around; an annular outer collar portion 58 formed integrally with a lower end of the cylindrical portion 56 in such a manner as to project outwardly in the horizontal direction H from the lower end of the cylindrical portion 56, an annular lower surface 57 of the annular outer collar portion 58 being in contact with the flat surface 10 of the floor 2; and an annular inner collar portion 62 which is formed integrally with the cylindrical portion 56 above at a position higher than the annular outer collar portion 58 in such a manner as to project inwardly in the horizontal direction H from a cylindrical inner surface 59 of the cylindrical portion 56, and which has a cylindrical inner peripheral surface 61 defining an opening 60 in which the rotating body 12 is capable of rotating.

[0049] With the base isolation supporting device 1 having the disengagement prevention mechanism 51, as shown in FIG. 5, in the rotation of the rotating body 12 in the R direction more than a fixed degree due to the tremor of an earthquake in the horizontal direction H accompanying the large rotational angle θ of the rotating body 12 about the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 7 of the support 8, the rotating body 12 is adapted to collide against and contact a lower surface 63 of the ceiling portion 55 which is the inner surface of the enclosure body 52, to thereby inhibit any further rotation. Thus, in the rotation of the rotating body 12 more than a fixed degree about the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 7 of the support 8, the enclosure body 52 having the lower surface 63 of the ceiling portion 55 which is the inner surface which the rotating body 12 contacts is adapted to prevent the disengagement of the rotating body 12 from the partially spherical portion 24 of the support 8.

[0050] According to the base isolation supporting device 1 having the disengagement prevention mechanism 51, even if the rotating body 12 tends to be rotated largely by an unexpected large tremor in the horizontal direction H, the disengagement of the rotating body 12 from the support 8 can be prevented by inhibiting the rotation of the rotating body 12 more than a fixed degree, with the result that it is possible to prevent the fall or the like of the fixture 3, making it possible to minimize the damage caused by an earthquake.

[0051] With the disengagement prevention mechanism 51 having the enclosure body 52, since the annular outer collar portion 58 is provided which is in contact with the flat surface 10 at the annular lower surface 57 thereof in the stationary state of the base isolation supporting device 1, an interior 65 of the enclosure body 52 in the stationary state of the base isolation supporting device 1 can be sealed with respect to the outside, so that it is possible to prevent ingress of dust into that interior 65 and avoid faulty operation of the base isolation supporting device 1 due to the dust. It should be noted that the function of the elastic body 43 of the rotating body 12 shown in FIG. 3 can be obtained satisfactorily by providing an elastic plate similar to the elastic body 43 on the annular lower surface 57 by means of bonding or the like, or by providing a clearance gap approximately equal to the thickness of the elastic body 43 between the annular lower surface 57 and the flat surface 10.

[0052] In the above-described base isolation supporting device 1, the support 8 is affixed to the outer casing 4 of the fixture 3, and the rotating body 12 at its cross-sectionally circular arc-shaped convex outer surface 11 is rollably brought into contact with the flat surface 10 of the floor 2. Alternatively, however, the support 8 at the threaded portion 21 may be affixed to the floor 2, and the cross-sectionally circular arc-shaped convex outer surface 11 of the rotating body 12 may be rotatably brought into contact with a flat surface 71 which is the lower surface of the outer casing 4 of the fixture 3. In other words, a combination assembly of the support 8 and the rotating body 12 may be set such that the top and the bottom thereof are in reverse. In the base isolation supporting device having a top-bottom inverted arrangement, it suffices if the center O2, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 11 of the rotating body 12, is positioned eccentrically with the amount of eccentricity δ downwardly toward the floor 2 side in the vertical direction V with respect to the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped concave outer surface 9 of the rotating body 12, in the stationary state of the base isolation supporting device.

[0053] In a base isolation supporting device 1a in accordance with a further embodiment shown in FIG. 6 includes a support 8a which is adapted to be affixed by the screw 5 or the like through the fitting 6 to the lower portion of the outer casing 4 of the fixture 3, in order to receive the load, acting in the vertical direction V, of the fixture 3 to be supported on the floor 2, the support 8a having a cross-sectionally circular arc-shaped convex outer surface 7a with the center O1, i.e., the center of curvature thereof; and a rotating body 12a which has a cross-sectionally circular arc-shaped concave outer surface 9a with a shape complementary to the cross-sectionally circular arc-shaped convex outer surface 7a of the support 8a and a center of curvature at the same position as the center O1, and which, at the cross-sectionally circular arc-shaped concave outer surface 9a, is adapted to be brought into contact with the cross-sectionally circular arc-shaped convex outer surface 7a slidably and rotatably in the R direction about the center O1, while, at a cross-sectionally circular arc-shaped convex outer surface 11a having the center O2, i.e., a center of curvature thereof, coming into contact with the flat surface 10 of the floor 2 rotatably in the R direction about the center O2, namely, coming into contact therewith rollably about the center O2, the rotating body 12a being adapted to receive together with the support 8a the load, acting in the vertical direction V, of the fixture 3 via the support 8a.

[0054] The support 8a has a columnar main body 23a having a threaded portion 21a at an upper portion thereof and a sliding portion 27a which is formed integrally with a lower portion of the main body 23a in such a manner as to be disposed between the main body 23a and the rotating body 12a and has the cross-sectionally circular arc-shaped convex outer surface 7a constituted by a partially spherical convex surface 26a as a portion of a spherical surface. The main body 23a is fixed to the fitting 6 at the threaded portion 21a positionally adjustably in the vertical direction V by the pair of nuts 25 which are threadedly engaged with the threaded portion 21a. The main body 23a is adapted to be affixed to the lower portion of the outer casing 4 of the fixture 3 by means of the fitting 6. The sliding portion 27a has a disk portion 22a formed integrally with the lower portion of the main body 23a and a partial spherical portion 24a formed integrally with the disk portion 22a and having the partially spherical convex surface 26a.

[0055] The rotating body 12a includes the cross-sectionally circular arc-shaped concave outer surface 9a constituted by the partially spherical concave surface 31a as a portion of a spherical surface, the cross-sectionally circular arc-shaped convex outer surface 11a constituted by a partially spherical convex surface 32a as a portion of a spherical surface, and an annular end face 33 whose inner peripheral edge is continuously connected to the cross-sectionally circular arc-shaped concave outer surface 9a and whose outer peripheral edge is continuously connected to the cross-sectionally circular arc-shaped convex outer surface 11a. The rotating body 12a is slidingly rotatable with respect to the cross-sectionally circular arc-shaped convex outer surface 7a of the support 8a in the R direction about the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a. The cross-sectionally circular arc-shaped convex outer surface 11a has a radius of curvature r2 which is greater than a radius of curvature r1 of the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a. In the stationary state (the state shown in FIG. 6) of the base isolation supporting device 1a, the center O2, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 11a of the rotating body 12a, is positioned eccentrically with respect to the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a, upwardly toward the fixture 3 side in the vertical direction V with an amount of eccentricity δ(=r2−r1). In the stationary state of the base isolation supporting device 1a, the center O1, which is the center of curvature of both the cross-sectionally circular arc-shaped convex outer surface 7a of the support 8a and the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a, and the center O2, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 11a of the rotating body 12a, are positioned on the identical vertical line 35. Thus, the cross-sectionally circular arc-shaped convex outer surface 7a of the support 8a has the radius of curvature r1 identical to the radius of curvature r1 of the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a, so that the centers of curvature of the cross-sectionally circular arc-shaped convex outer surface 7a of the support 8a and the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a are located at the identical position, i.e., at the center O1.

[0056] In the case where a tremor in the horizontal direction H due to an earthquake is not applied to the floor 2, each of a plurality of, at least three, base isolation supporting devices 1a disposed at the lower portion of the outer casing 4 of the fixture 3 is in the stationary state shown in FIG. 6, and supports the fixture 3 by sharing the load of the fixture 3 on the floor 2. When a tremor in the horizontal direction H due to an earthquake is applied to the floor 2, the rotating body 12a of each base isolation supporting device 1a rollingly rotates at the cross-sectionally circular arc-shaped convex outer surface 11a on the flat surface 10 of the floor 2 in the R direction about the center O1 with respect to the partially spherical portion 24a while accompanying the sliding of the cross-sectionally circular arc-shaped concave outer surface 9a with respect to the cross-sectionally circular arc-shaped convex outer surface 7a, as shown in FIG. 7. By virtue of this rotation, each base isolation supporting device 1a prevents the transmission to the fixture 3 of the tremor in the horizontal direction H applied to the floor 2, thereby supporting the fixture 3 in a base-isolated manner. Meanwhile, a return moment M=W.Math.δ.Math.sin θ (where W is the load applied to the rotating body 12a; 5 is the amount of eccentricity δ=(r2−r1); and θ is the angle of rotation of the rotating body 12a with respect to the vertical line 35) for returning to the stationary state occurs, at each rotated position of the rotating body 12a, to the rotating body 12a which is adapted to support the fixture 3 in a base-isolated manner and to lift the fixture 3 in the vertical direction V together with its rotation in the R direction because of the difference between the radius of curvature r2 of the cross-sectionally circular arc-shaped convex outer surface 11a and the radius of curvature r1 of the cross-sectionally circular arc-shaped concave outer surface 9a ascribable to the amount of eccentricity δ between the center O1 and the center O2. By virtue of this return moment M, the rotating body 12a which undergoes so-called pendular movement having a period T is returned to its rotational position in the stationary state upon the convergence of the pendular movement due to the dissipation of vibrational energy attributable to the sliding friction of the cross-sectionally circular arc-shaped concave outer surface 9a with respect to the cross-sectionally circular arc-shaped convex outer surface 7a as well as the rolling friction at the cross-sectionally circular arc-shaped convex outer surface 11a of the rotating body 12a with respect to the flat surface 10 of the floor 2 after the extinction of the tremor of the floor 2 in the horizontal direction H due to the earthquake, to thereby return the fixture 3 to its original position persisting prior to the earthquake tremor.

[0057] The period T of the pendular movement of the rotating body 12a is expressed by the formula (1), and in the case where θ is small, θ/sin θ≈1, with the result that the period T is expressed by the formula (2), and the smaller the amount of eccentricity δ (=r2−r1), which is the difference between the radius of curvature r2 of the cross-sectionally circular arc-shaped convex outer surface 11a and the radius of curvature r1 of the cross-sectionally circular arc-shaped concave outer surface 9a, the longer the period T becomes, whereas, to the contrary, the greater the amount of eccentricity δ (=r2−r1), the shorter the period T becomes.

[0058] With above-described base isolation supporting device 1a as well, the rotating body 12a has the cross-sectionally circular arc-shaped convex outer surface 11a which is adapted to be brought into contact with the flat surface 10 of the floor 2 rollably and rotatably, and, in the stationary state, the center O2, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 11a, is offset from the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped concave outer surface 9a, upwardly in the vertical direction V with the amount of eccentricity δ, with the result that the base isolation supporting device 1a can be installed by using as it is the flat surface 10 of the floor 2. Moreover, since the period T of the pendular movement of the rotating body 12a can be determined by the amount of eccentricity δ which is the difference between radius of curvature r1 of the cross-sectionally circular arc-shaped concave outer surface 9a and the radius of curvature r2 of the cross-sectionally circular arc-shaped convex outer surface 11a, it is possible to easily attain a long period. Moreover, since the cross-sectionally circular arc-shaped convex outer surface 7a is constituted by the partially spherical convex surface 26a, the cross-sectionally circular arc-shaped concave outer surface 9a is constituted by the partially spherical concave surface 31a, and the cross-sectionally circular arc-shaped convex outer surface 11a is constituted by the partially spherical convex surface 32a, namely, since the respective surfaces are constituted by spherical surfaces, the fixture 3 can be supported in a base-isolated manner with respect to the tremors of an earthquake in all directions in the horizontal direction H. In addition, since the position for mounting the support 8 to the fitting 6 is adapted to be adjustable by means of the threaded portion 21a and the nuts 25, the fixture 3 can be supported in a base-isolated manner at an arbitrary position in the vertical direction V.

[0059] Incidentally, with the base isolation supporting device 1a shown in FIG. 6, the rotating body 12a is formed of a one-piece body constituted by a rigid body. Alternatively, however, as shown in FIG. 8, the rotating body 12a may include a rigid body 42a having the partially spherical concave surface 31a constituted by the cross-sectionally circular arc-shaped concave outer surface 9a, an annular end face 33a, and a partially spherical convex surface 41a, as well as a natural rubber-made elastic body 43a secured to the partially spherical convex surface 41a of the rigid body 42a by vulcanization bonding and having the partially spherical convex surface 32a constituted by the cross-sectionally circular arc-shaped convex outer surface 11a. If the rotating body 12a is thus provided with the elastic body 43a as a coating layer for the rigid body 42a, the fixture 3 can be supported in a base-isolated manner with respect to the tremors of an earthquake in all directions in the horizontal direction H, and, by virtue of the elastic deformation of the elastic body 43a, the fixture 3 can be supported in a base-isolated manner with respect to the tremors of an earthquake in the vertical direction V applied to the floor 2, thereby making it possible to protect the fixture 3 itself and the article inside the fixture 3 as well. In addition, it becomes possible to obtain trigger action by the flattening of the cross-sectionally circular arc-shaped convex outer surface 11a due to the depression, caused by partial elastic deformation, of that portion of the elastic body 43a which receives the load in the vertical direction V in the stationary state.

[0060] In the base isolation supporting devices 1 shown in FIGS. 6 and 8, the cross-sectionally circular arc-shaped convex outer surface 7a of the support 8a has the center O1 at the identical position to the position of the center O1 of the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a, and has the radius of curvature r1 identical to the radius of curvature r1 of the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a. Alternatively, however, as shown in FIG. 9, the cross-sectionally circular arc-shaped convex outer surface 7a of the support 8a may have a center O3 on the identical vertical line 35 but at a different position in the vertical direction V from the position of the center O1 of the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a and a radius of curvature r3 smaller than the radius of curvature r1 of the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a. In this case, in comparison with the slidable surface contact between the cross-sectionally circular arc-shaped convex outer surface 7a and the cross-sectionally circular arc-shaped concave outer surface 9a in the base isolation supporting devices 1a shown in FIGS. 6 and 8, the cross-sectionally circular arc-shaped convex outer surface 7a and the cross-sectionally circular arc-shaped concave outer surface 9a are brought into slidable substantially point contact with each other.

[0061] With the above-described base isolation supporting device 1a, the possibility of the rotating body 12a coming off the support 8a occurs in the tremor of an earthquake accompanying the large rotational angle θ of the rotating body 12a. However, as shown in FIG. 10, the base isolation supporting device 1a may further have the above-described disengagement prevention mechanism 51 for preventing the disengagement of the rotating body 12a from the support 8a by inhibiting the rotation of the rotating body 12a more than a fixed degree as the rotating body 12a collides against the disengagement prevention mechanism 51 in the rotation in the R direction of the rotating body 12a about the center O1 which is the center of curvature of the cross-sectionally circular arc-shaped concave outer surface 9a with respect to the support 8a. In the disengagement prevention mechanism 51, the enclosure body 52 encloses the rotating body 12a, the cylindrical portion 56 surrounds the rotating body 12a from around, and the rotating body 12a is rotatable in the opening 60.

[0062] With the base isolation supporting device 1a having the disengagement prevention mechanism 51, as shown in FIG. 11, in the rotation of the rotating body 12a in the R direction more than a fixed degree due to the tremor of an earthquake in the horizontal direction H accompanying the large rotational angle θ of the rotating body 12a about the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 7a of the support 8a, the rotating body 12a is adapted to collide against and contact the lower surface 63 of the ceiling portion 55, to thereby inhibit any further rotation in the R direction. Thus, in the rotation of the rotating body 12a more than a fixed degree about the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 7a of the support 8a, the enclosure body 52 having the lower surface 63 of the ceiling portion 55 which is the inner surface which the rotating body 12a contacts is adapted to prevent the disengagement of the rotating body 12a from the sliding portion 27a of the support 8a in the same way as described above.

[0063] According to the base isolation supporting device 1a having the disengagement prevention mechanism 51, in the same way as described above, even if the rotating body 12a tends to be rotated largely by an unexpected large tremor in the horizontal direction H, the disengagement of the rotating body 12a from the support 8a can be prevented by inhibiting the rotation of the rotating body 12a more than a fixed degree, with the result that it is possible to prevent the fall or the like of the fixture 3, making it possible to minimize the damage caused by an earthquake.

[0064] Also with the disengagement prevention mechanism 51 for the base isolation supporting device 1a, since there is provided the annular outer collar portion 58 which is in contact with the flat surface 10 at the annular lower surface 57 thereof in the stationary state of the base isolation supporting device 1a, the interior 65 of the enclosure body 52 in the stationary state of the base isolation supporting device 1a can be sealed with respect to the outside, so that it is possible to prevent ingress of dust into that interior 65 and avoid faulty operation of the base isolation supporting device 1a due to the dust. Also in the base isolation supporting device 1a in accordance with this embodiment, an elastic plate may be provided on the annular lower surface 57, or a clearance gap may be provided between the annular lower surface 57 and the flat surface 10.

[0065] In the above-described base isolation supporting device 1a, the support 8a is affixed to the outer casing 4 of the fixture 3, and cross-sectionally circular arc-shaped convex outer surface 11a of the rotating body 12 is rollably brought into contact with the flat surface 10 of the floor 2. Alternatively, however, in the same way as the base isolation supporting device 1, the support 8a at the threaded portion 21a may be affixed to the floor 2, and the cross-sectionally circular arc-shaped convex outer surface 11a of the rotating body 12a may be rotatably brought into the flat surface 71 which is the lower surface of the outer casing 4 of the fixture 3. In other words, a combination assembly of the support 8a and the rotating body 12a may be set such that the top and the bottom thereof are in reverse. In the base isolation supporting device having a top-bottom inverted arrangement, it suffices if the center O2, which is the center of curvature of the cross-sectionally circular arc-shaped convex outer surface 11a of the rotating body 12a, is positioned eccentrically with the amount of eccentricity δ downwardly toward the floor 2 side in the vertical direction V with respect to the center O1, which is the center of curvature of the cross-sectionally circular arc-shaped concave outer surface 9a of the rotating body 12a, in the stationary state of the base isolation supporting device.

DESCRIPTION OF REFERENCE NUMERALS

[0066] 1, 1a: base isolation supporting device [0067] 2: floor [0068] 3: fixture [0069] 4: outer casing [0070] 5: screw [0071] 6: fitting [0072] 7, 7a, 11, 11a: cross-sectionally circular arc-shaped convex outer surface [0073] 8, 8a: support [0074] 9, 9a: cross-sectionally circular arc-shaped concave outer surface [0075] 10: flat surface [0076] 12, 12a: rotating body [0077] O1, O2: center [0078] d: distance [0079] r1: radius of curvature [0080] r2: radius of curvature