Damping device

Details Damping device Damping device

2001-11-16

2002-12-31

Schwartz, Christopher P. (Department: 3683)

Brakes

Internal-resistance motion retarder

Using viscosity of fluid medium

C188S290000, C188S293000

Reexamination Certificate

active

06499573

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a damping device to be utilized for a seismic base isolation system or like preventing vibration at an occurrence of an earthquake or like from being transmitted from a base structure to a building structure and for a vibration suppression system or like preventing a multistoried building from being swung itself at an occurrence of an earthquake.
BACKGROUND ART
In a prior art, there is known a damping device for seismic base isolation system or vibration suppression system such as shown in
FIG. 6
as damping device
1
, which is disclosed in Japanese Patent Laid-open Publication No. HEI 10-184757. Such damping device
1
is disposed between two object (objective) portions
2
a,
2
b
of a building or like for damping vibration of the object portions
2
a,
2
b.
With reference to
FIG. 6
, the damping device
1
is provided with a casing
3
, a ball screw mechanism
5
for converting a linear motion between the object portions
2
a
and
2
b
to a rotational motion of a cylindrical rotation member
4
and a damping member
6
resisting the rotational motion of the rotation member
4
. The ball screw mechanism
5
includes a nut
7
which is supported rotatably by the casing
3
and connected to the rotation member
4
. The casing
3
has a base end
3
b
secured to one
2
b
of the object portions. The ball screw mechanism
5
includes a screw shaft
8
projecting outward from a front end portion
3
a
of the casing
3
and fixed to the other one
2
a
of the object portions.
The damping member
6
accommodates a viscous fluid
9
sealed between an inner peripheral portion of the casing
3
and an outer peripheral portion of the rotation member
4
. According to such structure, the relative linear motion between the object portions
2
a,
2
b
is converted to the rotational motion of the rotation member
4
by means of the ball screw mechanism
5
, and at this time, the damping member
6
acts to resist the rotational motion of the rotation member
4
.
Further, the above Japanese Publication discloses a modified damping device
11
such as shown in FIG.
7
. With reference to
FIG. 7
, the modified damping device
11
is provided, as is similar to the damping device
1
of
FIG. 6
, with a casing
13
, a ball screw mechanism
15
for converting a linear motion between the object portions
2
a
and
2
b
to a rotational motion of a cylindrical rotation member
14
and a damping member
16
resisting the rotational motion of the rotation member
14
. In this modified damping device
11
, differing from the damping device
1
of
FIG. 6
, a gap W is formed between the front end (lower end as viewed) portion of the cylindrical rotation member
14
and the bottom portion of the casing
13
so that viscous fluid
19
fills not only outside the rotation member
14
but also inside the rotation member
14
, and the viscous fluids inside and outside the rotation member
14
are communicated with each other at the inner lower portion of the casing
13
.
In the damping devices
1
and
11
of the conventional structures, in order to impart a large damping force (damping power) to the rotational member
4
(
14
), it is necessary to increase contacting area between the rotation member
4
(
14
) and the viscous fluid
9
(
19
). However, in the conventional damping device
1
of
FIG. 6
, because only the outer peripheral surface of the rotation member
4
contacts the viscous fluid
9
, it is difficult to make large the damping force per unit length in the axial direction of the rotation member
4
in its axial direction. In order to obviate such defects and make large the damping force, it becomes necessary to elongate the axial length of the rotation member
4
, resulting in increasing of the size of the rotation member
4
, i.e., entire damping device
1
, providing an inconvenience in production of the damping device.
On the other hand, in the damping device
11
of
FIG. 7
, since the inner and outer peripheral surfaces of the rotation member contact the viscous fluid
19
, the contacting area can be made large. However, in this structure, the viscous fluid
19
inside the rotation member
14
is rotated together with the rotation member
14
when rotated, and hence, the viscous fluid
19
inside the rotation member
14
cannot be fully shared. That is, the viscous fluid
19
inside the rotation member
14
cannot perform sufficient resisting function against the rotational motion of the rotation member
14
, and as a result, it becomes difficult to make large the damping force per unit length in the axial direction of the rotation member
14
, thus also providing a problem.
DISCLOSURE OF THE INVENTION
The present invention was conceived in consideration of the above circumstances in the prior art and aims to provide a damping device capable of making large a damping force per unit length of the damping device in its axial direction.
Hereunder, the present invention will be explained. Further, the description is made by adding reference numerals in the accompanying drawings for the sake of easy understanding of the present invention, but the present invention is not limited to the shown embodiment.
In order to achieve the above object, the inventors of the subject application provide a damping device (
20
,
50
) for substantially preventing vibration from transmitting or causing between two object portions which comprises a motion conversion section (
21
) for converting a relative linear motion between object portions to a rotational motion of a rotation member (
30
) and a damping section (
22
) resisting the rotational motion of the rotation member (
30
), wherein the damping section (
22
) is provided with an inner peripheral side sealing layer (
34
) disposed on an inner peripheral side of the rotation member (
30
) and an outer peripheral side sealing layer (
33
) disposed on an outer peripheral side of the rotation member, the inner peripheral side sealing layer (
34
) and the outer peripheral side sealing layer (
33
) being sealed with viscous medium so as to achieve a resisting function against the rotational motion of the rotation member (
30
). Further, in this aspect, as the motion conversion section, various mechanisms may be utilized as far as they can convert the linear motion to the rotational motion, and for example, ball screw mechanism, screw mechanism having a lead and a rack/pinion mechanism may be utilized.
According to the subject feature of the present invention mentioned above, since the inner peripheral side sealing layer and the outer peripheral side sealing layer contact the rotation member, while resisting the rotational motion of the rotation member, the damping force per unit length of the rotation member in its axial direction can be made large. Further, in the case where a damping force is needed approximately corresponding to that in the conventional damping device, the axial length of the rotation member can be reduced in substantially half length, thus making compact the entire structure of the rotation member, i.e., damping device, in addition to easy manufacturing thereof.
The present invention is further characterized in that the damping section (
22
) is further provided with an outer cylindrical member (
31
) disposed outside the rotation member (
30
) and an inner cylindrical member (
32
) disposed inside the rotation member (
30
) and secured to the outer cylindrical member (
31
), the outer peripheral side sealing layer (
33
) is arranged between the outer cylindrical member (
31
) and the rotation member (
30
) and the inner peripheral side sealing layer (
34
) is arranged between the rotation member (
30
) and the inner cylindrical member (
32
), the inner and outer peripheral side sealing layers (
34
) and (
33
) being sectioned from each other.
According to the invention of this aspect, the inner peripheral side sealing layer and the outer peripheral side sealing layer are shared, so that the sealing layers can surely resist the rotational motion of the rotation member. For this reaso

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