JP2000282706A - Vibration isolator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent rolling of a seismically isolated body so long as an external force directly applied to the seismically isolated body does not exceed a predetermined value, by setting a conically concave surface at a suitable straight ascending gradient from an upper surface of a base plate to the periphery, and forming a concave portion having a predetermined slanting surface at the central portion of the upper surface of the base plate. SOLUTION: A base plate 1 has a concave portion 11a formed at a central portion of an upper surface 11 thereof, which concave portion has a slanting surface at a gradient of an angle θ1 larger than a slanting angle θ of a slanting surface (conically concave surface), with a diameter L. The slanting surface is, similar to the upper surface 11, set at a straightly ascending gradient from the center to the outside, and the diameter L of the concave portion 11a is smaller than a diameter L1 of a bearing ball 2. Provided that a dimension between contact points of the bearing ball 2 to the concave portion 11a is set to L2, if a relationship of L2<=L<L1 holds, an externally operating force for rolling the bearing ball 2 on the concave portion 11a becomes larger than an externally operating force for rolling the same on the upper surface 11 which is the slanting surface at the periphery of the concave portion 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an improvement of a seismic isolation device.

[0002]

2. Description of the Related Art In recent years, in a stand or a building, a seismic isolation device is arranged between the base and the ground, so that a roll from the base or the ground is applied to the stand or a building. In some cases, seismic isolation is performed so as not to be propagated, and there are various proposals for seismic isolation devices.

[0003] Among them, for example, a seismic isolation device called a ball isolator includes, as shown in FIG. 3, a base plate 1 horizontally installed on a base B such as a base or ground,
A base-isolated body A such as a display stand or a building having a bearing ball 2 made of a large-diameter steel ball which is positioned above the base plate 1 and rolls on the upper surface 11 of the base plate 1.
And a main body 3 disposed in the main body.

At this time, the upper surface 11 of the base plate 1
Is set as a conical concave surface having a linear ascending slope at an appropriate angle θ from the center toward the outer periphery. As compared with the case where the so-called upper surface is formed of a curved surface, the bearing ball 2 Care is taken to avoid resonance when rolling.

[0005] Further, in the main body 3, the bearing ball 2 is set to have a structure (not shown) that comes into contact with a large number of small-diameter steel ball bearings housed in the main body 3. , Its rolling properties are guaranteed.

Therefore, in this seismic isolation device, for example, when rolling occurs on the base B, the bearing ball 2 moves up and down the upper surface 11 of the base plate 1 when viewed relatively. Therefore, the seismic isolated body A is prevented from swaying due to the swaying of the base B, that is, seismically isolated.

When the roll of the base B disappears, the bearing ball 2 returns to the center of the upper surface 11 of the base plate 1, and as shown in FIG. The seismic isolated body A stabilizes in a stationary state.

[0008]

However, the above-described seismic isolation device may be pointed out as having the following disadvantages.

That is, in the conventional seismic isolation device, in order to achieve a predetermined seismic isolation effect smoothly,
The bearing ball 2 is set so as to easily roll on the upper surface 11 of the base plate 1.

Therefore, for example, in a display stand,
Inadvertently touching the display stand may cause the display stand to roll easily, and in a building, there is a fear that the building may roll due to strong winds.

Therefore, although not shown, a damper is provided in addition to the seismic isolation device, and the damper is maintained in a so-called locked state as long as the base B does not sway. Proposals have been made to prevent seismic isolation body A from rolling.

Therefore, according to the proposal of installing a damper, for example, in a building, it is possible to prevent the building from being easily rolled in a strong wind beforehand. In addition, it is essential to install sensors to detect earthquakes, and to install a control device that processes signals from these sensors and outputs predetermined signals to the damper. There is a problem that the cost is increased, and the versatility cannot be expected.

The present invention has been made in view of the above circumstances, and has as its object to exert a predetermined seismic isolation function when a base rolls due to an earthquake. As long as the external force acting directly on the seismic isolated body does not exceed a certain level, the seismic isolated body will not roll, and its simple configuration will not lead to high cost, and its versatility is expected to improve. It is to provide a seismic isolation device that is most suitable for performing.

[0014]

Means for Solving the Problems In order to achieve the above-mentioned object, the structure of the seismic isolation device according to the present invention basically comprises a base plate horizontally installed on a base such as a base or ground, While having a bearing ball positioned above the base plate and having a bearing ball rolling on the upper surface of the base plate, a main body disposed on the seismic isolated body side such as a display stand or a building, and the upper surface of the base plate is In a seismic isolation device that is set to a conical concave surface that forms a linear upward slope at an appropriate angle from the center to the outer periphery, the inclination angle of the inclined surface that is the outer peripheral side of this central portion is located at the center of the upper surface of the base plate. It is assumed that a concave portion having an inclined surface with a larger inclination angle is formed.

In the above-described basic configuration,
More specifically, it is preferable that the inclined surface of the concave portion is set so as to have a linear upward slope from the center toward the outer periphery.

Further, the concave portion may have a shallow concave portion in the center portion having an inclined surface having a smaller inclination angle than the inclined surface of the concave portion on the outer peripheral side.

Further, the shallow concave portion may be set so as to have a linear upward slope from the center to the outer periphery, or may be set to a curved concave surface corresponding to the curvature of the outer peripheral surface of the bearing ball. It may be done.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiment. Even in a seismic isolation device according to the present invention, the seismic isolation device shown in FIG. Like the device, it is a seismic isolation device called a so-called ball isolator.

Therefore, in the illustrated embodiment,
Where the configuration is the same as that of the above-described conventional example, the same reference numerals are given only in the drawings, and a detailed description thereof will be omitted except where necessary. The explanation will focus on where it is.

That is, as shown in FIG. 1, in the seismic isolation device according to the present invention, the upper surface 11 of the base plate 1 is provided.
A concave portion 11a having a diameter L having an inclined surface having an inclination angle θ1 larger than the inclination angle θ of the inclined surface (conical concave surface) on the outer peripheral side of the central portion. It is.

At this time, the inclined surface of the concave portion 11a is
As in the case of 1, it is assumed that it is set so as to have a linear upward gradient from the center to the outer periphery, and the diameter L of the concave portion 11a is smaller than the diameter L1 of the bearing ball 2.

By setting the inclined surface of the concave portion 11a so as to have a linear upward slope from the center to the outer periphery, the inclined surface of the upper surface 11 has the same characteristics as that of the inclined surface except that the angle is different. Thus, resonance when the bearing ball 2 rolls can be avoided.

On the other hand, when the distance between the contact points of the bearing ball 2 with the concave portion 11a is L2, that is, L2 ≦ L <L
When it is set to 1, the external force effect for rolling the bearing ball 2 on the concave portion 11a is larger than the external force effect for rolling the bearing ball 2 on the upper surface 11, which is the inclined surface on the outer peripheral side of the concave portion 11a. Will be.

That is, the external force P for rolling the bearing ball 2 on the concave portion 11a is P = m · tan (θ1 + φ). At this time, m; the vertical force acting on the bearing ball 2 from the seismic isolated body A side; and the friction angle between the bearing ball 2 and the base plate 1 φ = arctanμ (μ; starting friction coefficient).

From the above, if the external force P for rolling the bearing ball 2 is larger than the external force F for moving the seismic isolated body A, that is, if P ≧ F, it is caused by something other than an earthquake, for example, a strong wind. The rolling of the bearing ball 2 can be prevented.

The range (L) of the recess 11a is the same as or slightly larger than the range (L2) of contact with the base plate 1 when the bearing ball 2 is in a so-called stationary state and is at the center of the base plate 1. As a result, the response acceleration when the bearing ball 2 starts rolling in the concave portion 11a becomes larger than the response acceleration on the outer peripheral side of the concave portion 11a.

However, the response acceleration when the bearing ball 2 comes out of the concave portion 11a and rolls on the upper surface 11 on the outer peripheral side of the concave portion 11a due to the earthquake does not cause any problem because it is the same as the conventional one.

Since the bearing ball 2 rolls exclusively during an earthquake on the upper surface 11, which is the outer peripheral side of the concave portion 11a, the presence of the concave portion 11a on the inner peripheral side means that from the original seismic isolation operation. It does not matter.

Furthermore, even if the bearing ball 2 rolls in the concave portion 11a when the earthquake is settled, the bearing ball 2 does not return to the center of the concave portion 11a by linear motion, but in a loop shape. Since it moves, the inclination angle θ up to that point
It can be said that even if the inclination angle becomes θ1, the change is not so large as to cause a so-called shock.

As a result, even if the bearing ball 2 rolls on the base plate 1 to exert the seismic isolation function, the seismic isolated body A is not rolled by an external force such as a strong wind. Thus, a predetermined seismic isolation function can be exerted.

In the above description, it is assumed that the bearing ball 2 rolls exclusively in the event of an earthquake on the upper surface 11, which is the outer peripheral side of the concave portion 11a. In the case of a strong earthquake and a relatively weak earthquake having a seismic intensity of 1 to 3, it is considered that the bearing ball 2 rolls so as to move back and forth while passing through the center of the base plate 1 at the concave portion 11a. .

In this case, since the angle at which the bearing ball 2 protrudes toward the center or the angle at which the bearing ball 2 escapes from the opposite center is large, there is a concern that vibration may occur near the center.

Therefore, as in the embodiment shown in FIG.
The concave portion 11a may have a shallow concave portion 11c having an inclined surface having an inclination angle θ2 smaller than the inclination angle θ1 of the inclined surface of the concave portion 11a on the outer peripheral side in the center.

Incidentally, the diameter L3 of the shallow recess 11c
And the diameter L of the recess 11a and the bearing ball 2
The relationship of the range L2 contacting 1c is L2 ≦ L3 <L.

The relationship between the inclination angle θ2 of the shallow recess 11c, the inclination angle θ1 of the recess 11a and the inclination angle θ of the upper surface 11 is θ <θ1> θ2, and θ = θ2 or θ.
≠ θ2.

The shallow recess 11c is
Like the upper surface 11 and the upper surface 11, a linear upward gradient is set from the center to the outer periphery.

Therefore, in the case of this embodiment, even if the bearing ball 2 rolls back and forth while passing through the center of the base plate 1 in the shallow recess 11b, the bearing ball 2 is directed toward the center. Since the angle of entry or the angle of exit from the opposite center is smaller than the inclination angle θ1 of the recess 11a, no vibration occurs near the center.

In each of the above embodiments, the concave portion 11
a and the center 11 of the shallow recess 11b
c, i.e., tentatively, within the range indicated by the symbol L2 in the figure,
Considering the time when the bearing ball 2 is in a stationary state, the bearing ball 2 may be set to a curved surface that matches the curvature of the outer peripheral surface.

In this case, the stability of the bearing ball 2 in the stationary state is easily improved as compared with the case where the central portion 11c of the concave portion 11a or the shallow concave portion 11b is formed in a conical concave surface. Is advantageous.

[0040]

As described above, according to the present invention, the concave portion having the inclined surface at the center of the upper surface of the base plate having a larger inclined angle than the inclined surface on the outer peripheral side of the central portion. Therefore, as long as there is no external force acting from the base, the external force acting on the seismic isolated body causes the bearing ball to roll on the upper surface on the outer peripheral side of the concave portion. Therefore, when the seismic isolated body is a building, for example, when the base rolls due to an earthquake, the roll caused by strong winds other than the earthquake does not appear, The specified seismic isolation function will be exhibited.

According to the present invention, a concave portion is formed at the center of the upper surface of the base plate, or a shallow concave portion is formed only at the center of the concave portion. This facilitates the manufacture and therefore does not increase the cost of the entire apparatus.

As a result, according to the present invention, not only does a predetermined seismic isolation function be exerted when the base rolls due to an earthquake, but also if the external force directly acting on the seismic isolated body does not exceed a certain level. In this method, the seismic isolated body does not roll, and the simple configuration does not cause an increase in cost.

[Brief description of the drawings]

FIG. 1 is a partially enlarged view showing a main part of a seismic isolation device according to the present invention in a partial cross section.

FIG. 2 is a partial schematic explanatory view showing a main part of a seismic isolation device according to another embodiment.

FIG. 3 is an overall view showing a seismic isolation device as a conventional example in a partial cross section.

[Explanation of symbols]

 Reference Signs List 1 base plate 2 bearing ball 3 main body 11 upper surface 11a recess 11b shallow recess 11c central portion A seismic isolated body B base L diameter of recess L1 diameter of bearing ball L2 dimension between contact points of bearing ball to recess L3 diameter of shallow recess θ Angle of inclination θ1 Angle of inclination of depression θ2 Angle of inclination of shallow depression

Claims (1)

[Claims] 1. A display device such as a display stand or a building having a base plate horizontally installed on a base such as a base and ground, and a bearing ball positioned above the base plate and rolling on the upper surface of the base plate. A seismic isolation device comprising: a main body disposed on the seismic isolation body side, and the upper surface of the base plate is set to a conical concave surface having a linear ascending slope at an appropriate angle from the center toward the outer periphery. A seismic isolation device characterized in that a concave portion having an inclined surface having a larger inclination angle than the inclination angle of the inclined surface on the outer peripheral side of the central portion is formed in the center of the upper surface of the base plate.