U.S. patent application number 09/471911 was filed with the patent office on 2002-04-25 for seismic isolation system for a crane.
This patent application is currently assigned to Mitsubishi Heavy Industries, Ltd.. Invention is credited to Harada, Hideaki, Ikeda, Hiroshi, OKUBO, Yoshiaki.
Application Number | 20020046677 09/471911 |
Document ID | / |
Family ID | 18498961 |
Filed Date | 2002-04-25 |
United States Patent
Application |
20020046677 |
Kind Code |
A1 |
OKUBO, Yoshiaki ; et
al. |
April 25, 2002 |
SEISMIC ISOLATION SYSTEM FOR A CRANE
Abstract
A seismic isolation system is provided with a swing bearing ring
consisting of an upper ring and a lower ring, which are rotatable
relatively, between a crane body and a traveling means. A lower
vertical shaft of a block pivotally supported on saddles of the
crane body is supported by a swing bearing provided at an eccentric
position on the upper ring. An automatic restoring mechanism is
provided which restores the swing of a horizontal lever, whose
proximal end is installed to the upper ring of the swing bearing
ring, around the centerline C2.
Inventors: |
OKUBO, Yoshiaki;
(Hiroshima-shi, JP) ; Ikeda, Hiroshi;
(Hiroshima-shi, JP) ; Harada, Hideaki;
(Hiroshima-shi, JP) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
Mitsubishi Heavy Industries,
Ltd.
|
Family ID: |
18498961 |
Appl. No.: |
09/471911 |
Filed: |
December 23, 1999 |
Current U.S.
Class: |
105/163.1 |
Current CPC
Class: |
B66C 9/12 20130101 |
Class at
Publication: |
105/163.1 |
International
Class: |
B61D 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 25, 1998 |
JP |
371583/1998 |
Claims
What is claimed is:
1. A seismic isolation system for a crane, provided between a crane
body and traveling means having a plurality of wheels for running
said crane body along a rail, comprising: a connecting mechanism
which allows relative movement of said crane body and said
traveling means while said crane body and said traveling means are
connected to each other when an earthquake occurs; a restraining
mechanism which keeps a steady relative positional relationship
between said crane body and said traveling means at the normal time
and allows a relative movement of said crane body and said
traveling means when said relationship is broken off by a seismic
force; energy absorbing means for restraining an increase in
relative movement of said crane body and said traveling means
caused by the occurrence of an earthquake; and a restoring
mechanism for restoring the positional relationship between said
crane body and said traveling means to the steady relationship.
2. A seismic isolation system for a crane, provided between a crane
body and traveling means having a plurality of wheels for running
said crane body along a rail, comprising a swing bearing ring
consisting of a lower ring installed horizontally on the side of
said traveling means and an upper ring engaging concentrically with
said lower ring so as to be rotatable relatively, and further
comprising a vertical shaft supporting swing bearing provided at an
eccentric position on the upper ring of said swing bearing ring; a
crane load supporting block having a lower vertical shaft supported
on said swing bearing; saddles installed at the lower part of said
crane body so as to pivotally support said block by using a
horizontal transverse shaft; a horizontal lever whose proximal end
is pivotally supported on the upper ring of said swing bearing ring
through said horizontal transverse shaft; and a horizontal lever
swing restoring mechanism which automatically restores said
horizontal lever to the neutral position while supporting the
distal end of said horizontal lever so as to be rotatable around
the vertical centerline of said swing bearing ring.
3. A seismic isolation system for a crane according to claim 2,
wherein said horizontal lever swing restoring mechanism comprises a
roller which is provided at the distal end of said horizontal lever
so as to be rotatable freely along the swing direction, and a guide
rail provided on said traveling means so as to be inclined downward
toward the middle position of the rail, which is the neutral
position.
4. A seismic isolation system for a crane according to claim 2,
wherein said horizontal lever swing restoring mechanism is composed
of a laminated rubber mounted between the lower face of said
horizontal lever and the upper face of said traveling means.
5. A seismic isolation system for a crane according to claim 2,
wherein said horizontal lever swing restoring mechanism comprises a
coil spring mounted between the lower face of said horizontal lever
and the upper face of said traveling means, and an antifriction
guide member interposed between said horizontal lever and said
traveling means so as to guide the distal end of said horizontal
lever in the swing direction of said lever along the upper face of
said traveling means.
6. A seismic isolation system for a crane according to any one of
claims 2 to 5, wherein braking means for braking the swinging
motion of said horizontal lever is provided on said traveling
means.
7. A seismic isolation system for a crane according to any one of
claims 2 to 6, wherein a damper for restraining the swinging motion
of said horizontal lever is mounted between said traveling means
and said horizontal lever.
8. A seismic isolation system for a crane, provided between a crane
body and traveling means having a plurality of wheels for running
said crane body along a rail, comprising: a laminated rubber
mounted between the lower face of said crane body and the central
portion of said traveling means; and transverse slide mechanisms
mounted between the lower face of said crane body and the upper
face of said traveling means at longitudinally symmetrical
positions with respect to said laminated rubber.
9. A seismic isolation system for a crane according to claim 8,
wherein a damper for restraining the transverse slide amount is
mounted between said crane body and said traveling means.
10. A seismic isolation system for a crane according to any one of
claims 2 to 9, wherein there are provided a vibration detecting
sensor for detecting vibrations of said crane body and said
traveling means when an earthquake occurs, a vibration control
section which sends a control signal for restraining the vibrations
of said crane body in response to a detection signal sent from said
sensor, and driving means which operates between said crane body
and said traveling means so as to restrain the vibrations of said
crane body according to the control signal sent from said vibration
control section.
11. A seismic isolation system for a crane, provided between a
crane body and traveling means having a plurality of wheels for
running said crane body along a rail, wherein the lower part of
said crane body and the upper center of said traveling means are
connected to each other by a universal joint mechanism, and
vibration damping mechanisms, which connect said crane body to said
traveling means, are interposed at positions on both sides of said
universal joint mechanism.
12. A seismic isolation system for a crane according to claim 11,
wherein said vibration damping mechanisms, which connect said crane
body to said traveling means, are interposed at longitudinally
symmetrical positions with respect to said universal joint
mechanism.
13. A seismic isolation system for a crane according to claim 11 or
12, wherein said universal joint mechanism comprises saddles
projecting downward from the lower part of said crane body, a
universal joint block whose upper part is pivotally mounted to said
saddles via a shaft in the travel direction, and a lower pivotally
mounting portion which pivotally mounts the lower part of said
universal joint block to a bearing on said traveling means via a
horizontal transverse shaft.
14. A seismic isolation system for a crane, provided between a
crane body and traveling means having a plurality of wheels for
running said crane body along a rail, comprising a laminated rubber
mounted between the lower face of said crane body and the central
portion of said traveling means; and turnover preventive
restraining members interposed between the lower face of said crane
body and the upper face of said traveling means at positions on
both sides of said laminated rubber.
15. A seismic isolation system for a crane according to claim 14,
wherein a trigger mechanism for restraining the horizontal relative
displacement between said crane body and said traveling means is
provided between said crane body and said traveling means, and when
said trigger mechanism is subjected to an excitation force having a
given value or larger by an earthquake, said restraint of relative
displacement is released.
16. A seismic isolation system for a crane, provided between a
crane body and traveling means having a plurality of wheels for
running said crane body along a rail, comprising inclined guide
means which guides the relative movement of said crane body when
said traveling means is displaced transversely by a seismic force
when an earthquake occurs, and additionally provides a restoring
function, said inclined guide means comprising a first swing
bearing ring consisting of a lower ring mounted on said traveling
means in an inclined state and an upper ring engaging
concentrically with said lower ring so as to be rotatable
relatively; an inclined beam provided integrally with the upper
ring of said first swing bearing ring; a second swing bearing ring
consisting of a lower ring mounted on the upper face of said
inclined beam so as to have the rotation centerline at a position
shifted horizontally from the rotation centerline of said first
swing bearing ring and an upper ring engaging concentrically with
said lower ring so as to be rotatable relatively; and a crane body
connecting portion for connecting the upper ring of said second
swing bearing ring to the lower part of said crane body.
17. A seismic isolation system for a crane according to claim 16,
wherein said crane body connecting portion comprises a hinge pin
type connecting member and a hydraulic cylinder each of which is
mounted between the upper ring of said second swing bearing ring
and said crane body.
18. A seismic isolation system for a crane according to claim 16 or
17, wherein a restraining mechanism, which restrains the rotation
of said inclined beam at the normal time and allows the rotation of
said inclined beam when the restraint is released by the seismic
force at the time of the occurrence of an earthquake, is mounted
between said inclined beam and said traveling means, and a damper
for restraining the rotation of said inclined beam is mounted
between said inclined beam and said traveling means.
19. A seismic isolation system for a crane, provided between a
crane body and traveling means having a plurality of wheels for
running said crane body along a rail, wherein a spring mechanism is
provided between said crane body and said traveling means to
elastically keep a steady positional relationship between said
crane body and said traveling means; a movable connecting mechanism
which connects said crane body to said traveling means while
allowing the relative displacement of said crane body, which
attempts to remain at the original position by the inertia force
acting on said crane body when said traveling means vibrates
transversely due to the occurrence of an earthquake, with respect
to said traveling means and a damper for restraining a relative
displacement between said crane body and said traveling means,
which is effected via said spring mechanism, are interposed between
said crane body and said traveling means; and said movable
connecting mechanism comprises a fist swing bearing ring consisting
of a lower ring mounted horizontally on the side of said traveling
means and an upper ring engaging concentrically with said lower
ring so as to be rotatable relatively, a horizontal beam provided
integrally with the upper ring of said first swing bearing ring, a
second swing bearing ring consisting of a lower ring mounted on the
upper face of said horizontal beam so as to have the rotation
centerline at a position shifted horizontally from the rotation
centerline of said first swing bearing ring and an upper ring
engaging concentrically with said lower ring so as to be rotatable
relatively, and a crane body connecting portion for connecting the
upper ring of said second swing bearing ring to the lower part of
said crane body.
20. A seismic isolation system for a crane according to claim 19,
wherein a restraining mechanism, which restrains the rotation of
said horizontal beam at the normal time and allows the rotation of
said horizontal beam when the restraint is released by the seismic
force at the time of the occurrence of an earthquake, is mounted
between said horizontal beam and said traveling means.
Description
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
[0001] 1. Field of the Invention
[0002] The present invention relates to a seismic isolation system
for a crane, which prevents derailment and the like of a large
crane caused by an earthquake.
[0003] 2. Description of Related Art
[0004] A "Overhead Traveling Crane" disclosed in Japanese Patent
Publication No. 63-356 (No. 356/988) is well known as a crane
equipped with a seismic isolation system.
[0005] This "Overhead Traveling Crane" is, as shown in FIGS. 24 and
25, configured so that horizontal shafts 152 are mounted on saddles
151 on both sides of a narrow girder-shaped crane body 150, a track
154 having two traveling wheels 153 which travel on a rail 157 is
provided on the horizontal shafts 152 so as to be slidable, and
there is provided a vibration damping mechanism consisting of
compression springs 155 and dampers 156, which are disposed between
the opposed faces of the inside face of the saddle 151 and the
track 154 so as to be parallel with the horizontal shafts 152.
[0006] On the crane of this type having the girder-shaped crane
body 150, if an earthquake occurs, the crane body 150 is mainly
subjected to only an excitation force perpendicular to the crane
traveling direction as a dangerous external force, and the
excitation force in this direction is damped by the action of the
compression springs 155 and the dampers 156 to prevent the wheels
from being damaged or derailed.
[0007] On a large container crane, an unloader, and the like
provided on the ground, a crane body 1 is generally formed into a
portal type as shown in FIGS. 17 and 18. These figures show a
general construction of a container crane. This portal crane body 1
has traveling means 2 at four corners.
[0008] The traveling crane having such a portal crane body is
subjected to a transverse excitation force R perpendicular to the
travel direction, a transverse overturning moment M, a torsional
load S (rotary load) from the travel direction to the right and
left, and an impulsive axial load A by vibrations at the time of an
earthquake.
[0009] Also, on the traveling crane having a large portal crane
body, the height of the position of the center of gravity is very
high, and therefore the natural period is long as compared with the
overhead traveling crane, so that the transverse displacement of
the portal crane body also increases. Therefore, even if the
conventional vibration damping mechanism shown in FIG. 25 is
applied to the portal crane body, a stroke necessary for damping
the transverse excitation force R cannot be provided, and also
damping action against the overturning moment M and the torsional
load S cannot be provided.
OBJECT AND SUMMARY OF THE INVENTION
[0010] The present invention has been made in view of the above
situation, and accordingly an object thereof is to provide a
seismic isolation system for a crane, which is effective even for a
traveling crane having a portal crane body.
[0011] To achieve the above object, the present invention provides
a seismic isolation system for a crane, provided between a crane
body and traveling means having a plurality of wheels for running
the crane body along a rail, comprising: a connecting mechanism
which allows relative movement of the crane body and the traveling
means while the crane body and the traveling means are connected to
each other when an earthquake occurs; a restraining mechanism which
keeps a steady relative positional relationship between the crane
body and the traveling means at the normal time and allows a
relative movement of the crane body and the traveling means when
the relationship is broken off by a seismic force; energy absorbing
means for restraining an increase in relative movement of the crane
body and the traveling means caused by the occurrence of an
earthquake; and a restoring mechanism for restoring the positional
relationship between the crane body and the traveling means to the
steady relationship.
[0012] In the above-described seismic isolation system for a crane
in accordance with the present invention, the steady positional
relationship between the crane body and the traveling means is kept
by the restraining mechanism at the normal time. When an earthquake
occurs, however, the traveling means is displaced transversely, and
the crane body attempts to remain at the original position by the
inertia force, so that the restraining mechanism is released by the
seismic force. Therefore, a relative movement of the crane body and
the traveling means occurs, and the energy caused by the relative
movement is absorbed by the energy absorbing means. The relative
movement of the crane body and the traveling means is relaxed
properly by a damper mounted between the crane body and the
traveling means. Thus, the seismic isolation function is fulfilled
safely and properly.
[0013] Also, the present invention provides a seismic isolation
system for a crane, provided between a crane body and traveling
means having a plurality of wheels for running the crane body along
a rail, comprising a swing bearing ring consisting of a lower ring
installed horizontally on the side of the traveling means and an
upper ring engaging concentrically with the lower ring so as to be
rotatable relatively, and further comprising a vertical shaft
supporting swing bearing provided at an eccentric position on the
upper ring of the swing bearing ring; a crane load supporting block
having a lower vertical shaft supported on the swing bearing;
saddles installed at the lower part of the crane body so as to
pivotally support the block by using a horizontal transverse shaft;
a horizontal lever whose proximal end is pivotally supported on the
upper ring of the swing bearing ring through the horizontal
transverse shaft; and a horizontal lever swing restoring mechanism
which automatically restores the horizontal lever to the neutral
position while supporting the distal end of the horizontal lever so
as to be rotatable around the vertical centerline of the swing
bearing ring.
[0014] In the above-described seismic isolation system for a crane
in accordance with the present invention, the load of the crane
body is transmitted from the saddles installed on the crane body to
the traveling means through the crane load supporting block, the
swing bearing, and the swing bearing ring.
[0015] An axial load, a overturning moment load, and a radial load
applied to the crane body by an earthquake during the operation of
the crane are supported by the swing bearing ring and the swing
bearing on the traveling means.
[0016] Also, an excitation force applied in the radial direction
perpendicular to the travel direction of the traveling means acts
on the lower ring of the swing bearing ring on the traveling means
so as to turn the swing bearing, which is erected at an eccentric
position from the center of the swing bearing ring, around the
vertical centerline of the swing bearing ring together with the
horizontal lever. This turning force is automatically restrained by
the horizontal lever swing restoring mechanism provided between the
horizontal lever and the traveling means, whereby a damping
operation against the excitation force is performed.
[0017] In the seismic isolation system for a crane in accordance
with the present invention, the horizontal lever swing restoring
mechanism comprises a roller which is provided at the distal end of
the horizontal lever so as to be rotatable freely along the swing
direction, and a guide rail provided on the traveling means so as
to be inclined downward toward the middle position of the rail,
which is the neutral position.
[0018] When the guide rail for guiding the roller (or a wheel) at
the distal end of the horizontal lever mounted on the swing bearing
ring is provided so as to be inclined downward from both sides
thereof toward the rail middle position, which is the neutral
position, as described above, the operation in which the horizontal
lever having been swung by seismic vibrations is automatically
restored to the neutral position is performed properly when the
roller having been pushed against the guide rail by the gravity of
the crane body is automatically restored to the rail middle
position. Also, when the horizontal lever is swung by seismic
vibrations, the roller climbs the inclined face of the guide rail,
so that the swinging motion of the horizontal lever is
restrained.
[0019] Also, in the seismic isolation system for a crane in
accordance with the present invention, the horizontal lever swing
restoring mechanism is composed of a laminated rubber mounted
between the lower face of the horizontal lever and the upper face
of the traveling means.
[0020] When the horizontal lever swing restoring mechanism is
composed of the laminated rubber mounted between the lower face of
the horizontal lever and the upper face of the traveling means as
described above, the swinging motion of the horizontal lever is
properly restrained by the spring effect and damping effect of the
laminated rubber itself, and the operation in which the horizontal
lever is automatically restored to the swing amount zero position
(neutral position) is performed properly.
[0021] Further, in the seismic isolation system for a crane in
accordance with the present invention, the horizontal lever swing
restoring mechanism comprises a coil spring mounted between the
lower face of the horizontal lever and the upper face of the
traveling means, and an antifriction guide member interposed
between the horizontal lever and the traveling means so as to guide
the distal end of the horizontal lever in the swing direction of
the lever along the upper face of the traveling means.
[0022] When the horizontal lever swing restoring mechanism is
composed of the coil spring mounted between the lower face of the
horizontal lever and the upper face of the traveling means as
described above, as well, the swinging motion of the horizontal
lever is elastically restrained properly by the coil spring at the
time of an earthquake along with the operation of the antifriction
guide member such as a roller for guiding the horizontal lever in
the lever swing direction along the upper face of the traveling
means. Also, the operation in which the horizontal lever having
been swung by seismic vibrations is automatically restored to the
neutral position is performed properly by the automatic restoring
function of the coil spring.
[0023] Also, in the seismic isolation system for a crane in
accordance with the present invention, braking means for braking
the swinging motion of the horizontal lever is provided on the
traveling means.
[0024] When the braking means for braking the swinging motion of
the horizontal lever is provided as described above, an active
damping operation is performed when an earthquake occurs.
[0025] Further, in the seismic isolation system for a crane in
accordance with the present invention, a damper (hydraulic
vibration exciter) for restraining the swinging motion of the
horizontal lever is mounted between the traveling means and the
horizontal lever. Therefore, the operation in which the swinging
motion of the horizontal lever is restrained is performed
sufficiently even by the use of such a damper, whereby the
operation for actively damping the crane body can be performed when
seismic vibrations occur.
[0026] Also, the present invention provides a seismic isolation
system for a crane, provided between a crane body and traveling
means having a plurality of wheels for running the crane body along
a rail, comprising: a laminated rubber mounted between the lower
face of the crane body and the central portion of the traveling
means; and transverse slide mechanisms mounted between the lower
face of the crane body and the upper face of the traveling means at
longitudinally symmetrical positions with respect to the laminated
rubber.
[0027] In the above-described seismic isolation system for a crane
in accordance with the present invention, when a transverse
excitation force is applied to the crane body by an earthquake, the
crane body slides transversely while supporting a bending moment by
using the transverse slide mechanisms. At this time, the sliding
force between the crane body and the traveling means is absorbed by
the deflection of the laminated rubber, and the crane body is
automatically restored to the normal position with respect to the
traveling means by the restoring force of the laminated rubber.
[0028] In the seismic isolation system for a crane in accordance
with the present invention, a damper for restraining the transverse
slide amount is mounted between the crane body and the traveling
means. Therefore, the transverse movement of the crane body is
restrained properly when seismic vibrations occur, along with the
operation in which the transverse slide amount is restrained by
such a damper.
[0029] Also, in the seismic isolation system for a crane in
accordance with the present invention, there are provided a
vibration detecting sensor for detecting vibrations of the crane
body and the traveling means when an earthquake occurs, a vibration
control section which sends a control signal for restraining the
vibrations of the crane body in response to a detection signal sent
from the sensor, and driving means which operates between the crane
body and the traveling means so as to restrain the vibrations of
the crane body according to the control signal sent from the
vibration control section.
[0030] In the above-described seismic isolation system for a crane
in accordance with the present invention, vibrations of the
traveling means are detected by the vibration detecting sensor and
taken in the vibration control section when seismic vibrations
occur, and the driving means is controlled by the control signal
sent from the control section so that the crane body is isolated
from the vibrations of the traveling means. Therefore, the
transverse vibrations of the crane body caused by an earthquake are
restrained actively.
[0031] Further, the present invention provides a seismic isolation
system for a crane, provided between a crane body and traveling
means having a plurality of wheels for running the crane body along
a rail, wherein the lower part of the crane body and the upper
center of the traveling means are connected to each other by a
universal joint mechanism, and vibration damping mechanisms, which
connect the crane body to the traveling means, are interposed at
positions on both sides of the universal joint mechanism.
[0032] In the above-described seismic isolation system for a crane
in accordance with the present invention, the vibration damping
mechanisms located on both sides of the universal joint mechanism
are balanced mutually so as to keep the universal joint block
vertical at the normal time. In this state, the weight of the crane
body is transmitted as an axial load to the traveling means through
the universal joint mechanism.
[0033] Also, the axial load, the overturning load, and the radial
load applied to the crane body when seismic vibrations occur are
also transmitted similarly to between the traveling means and the
crane body through the universal joint mechanism.
[0034] A transverse excitation force applied to the crane body
perpendicularly to the travel direction by seismic vibrations is
absorbed as vibrations with a long vibration period by the turning
motion of the crane body around the longitudinal horizontal axis in
the universal joint mechanism.
[0035] Also, when the vibration damping mechanisms, which connect
the crane body to the traveling means, are interposed at
longitudinally symmetrical positions with respect to the universal
joint mechanism, a longitudinal excitation force applied to the
crane body by seismic vibrations is also damped properly.
[0036] Further, when the universal joint mechanism comprises
saddles projecting downward from the lower part of the crane body,
a universal joint block whose upper part is pivotally mounted to
the saddles via a shaft in the travel direction, and a lower
pivotally mounting portion which pivotally mounts the lower part of
the universal joint block to a bearing on the traveling means via a
horizontal transverse shaft, the construction of the universal
joint mechanism is compact and has a high strength, and the
arrangement thereof is effected properly.
[0037] Further, the present invention provides a seismic isolation
system for a crane, provided between a crane body and traveling
means having a plurality of wheels for running the crane body along
a rail, comprising a laminated rubber mounted between the lower
face of the crane body and the central portion of the traveling
means; and turnover preventive restraining members interposed
between the lower face of the crane body and the upper face of the
traveling means at positions on both sides of the laminated
rubber.
[0038] In the above-described seismic isolation system for a crane
in accordance with the present invention, a transverse relative
displacement produced between the crane body and the traveling
means by an earthquake is absorbed by the spring element and the
friction damping due to the deformation of the laminated rubber. At
the same time,the overturning moment load applied along with the
transverse radial load is supported by the resisting force of the
turnover preventive restraining members on both sides, and the
restoring operation to the deflection zero position is performed
properly by the restoring force of the laminated rubber.
[0039] Also, in the seismic isolation system for a crane in
accordance with the present invention, a trigger mechanism for
restraining the horizontal relative displacement between the crane
body and the traveling means is provided between the crane body and
the traveling means, and when the trigger mechanism is subjected to
an excitation force having a given value or larger by an
earthquake, the restraint of relative displacement is released.
[0040] In the above-described seismic isolation system for a crane,
when an excitation force exceeding the given value is applied to
the crane by an earthquake, the trigger mechanism is released, and
the seismic isolation function is fulfilled by the laminated rubber
and the turnover preventive restraining members on both sides of
the laminated rubber. In the normal state in which no earthquake
occurs, the crane body and the traveling means are connected to
each other integrally by the trigger mechanism, so that the
rigidity of the whole crane is maintained.
[0041] Also, the present invention provides a seismic isolation
system for a crane, provided between a crane body and traveling
means having a plurality of wheels for running the crane body along
a rail, comprising inclined guide means which guides the relative
movement of the crane body when the traveling means is displaced
transversely by a seismic force when an earthquake occurs, and
additionally provides a restoring function, the inclined guide
means comprising a first swing bearing ring consisting of a lower
ring mounted on the traveling means in an inclined state and an
upper ring engaging concentrically with the lower ring so as to be
rotatable relatively; an inclined beam provided integrally with the
upper ring of the first swing bearing ring; a second swing bearing
ring consisting of a lower ring mounted on the upper face of the
inclined beam so as to have the rotation centerline at a position
shifted horizontally from the rotation centerline of the first
swing bearing ring and an upper ring engaging concentrically with
the lower ring so as to be rotatable relatively; and a crane body
connecting portion for connecting the upper ring of the second
swing bearing ring to the lower part of the crane body.
[0042] In the above-described seismic isolation system for a crane
in accordance with the present invention, the load of the crane
body is supported via the first swing bearing on the side of the
traveling means, the inclined beam at the middle part, and the
second swing bearing ring on the side of the crane body, and
further via the crane body connecting portion.
[0043] When the traveling means moves in the transverse direction
together with the rail at the time of the occurrence of earthquake,
since the first swing bearing ring and the second swing bearing
ring have the mutually shifted respective rotation centerlines, the
crane body attempts to remain by the inertia force and shifts
transversely relative to the traveling means. Accordingly, the
inclined beam is swung and pushes up the crane body in cooperation
with the second swing bearing ring on the beam. Thus, the crane
body mainly moves vertically due to the reciprocating transverse
movement of the traveling means caused by an earthquake, so that
the period of the crane body is made long, and the seismic
isolation function is fulfilled.
[0044] Further, in the seismic isolation system for a crane in
accordance with the present invention, the crane body connecting
portion comprises a hinge pin type connecting member and a
hydraulic cylinder each of which is mounted between the upper ring
of the second swing bearing ring and the crane body.
[0045] When the upper ring of the second swing bearing ring and the
crane body are connected to each other by the hinge pin type
connecting member and the hydraulic cylinder so that the
inclination is adjustable as described above, the crane body can be
kept horizontal by the extending contracting adjustment of the
hydraulic cylinder according to the face angle of the inclined
beam, and the relative relationship of the crane body with the
second swing bearing ring can be fixed properly.
[0046] Also, in the seismic isolation system for a crane in
accordance with the present invention, a restraining mechanism,
which restrains the rotation of the inclined beam at the normal
time and allows the rotation of the inclined beam when the
restraint is released by the seismic force at the time of the
occurrence of an earthquake, is mounted between the inclined beam
and the traveling means, and a damper for restraining the rotation
of the inclined beam is mounted between the inclined beam and the
traveling means.
[0047] When the restraining mechanism such as a shear pin or a
brake is provided between the inclined beam and the traveling means
so that the restraining mechanism is released only when an
earthquake occurs as described above, the inclined beam is fixed at
the normal time, so that a stable operation is performed as in the
case of the conventional crane equipment. When the restraining
mechanism is released by the seismic force and the inclined beam is
turned reciprocatively, since the damper is provided to restrain
the turning of the inclined beam, the seismic energy is absorbed
while the relative movement of the crane body and the traveling
means is relaxed properly.
[0048] Further, the present invention provides a seismic isolation
system for a crane, provided between a crane body and traveling
means having a plurality of wheels for running the crane body along
a rail, wherein a spring mechanism is provided between the crane
body and the traveling means to elastically keep a steady
positional relationship between the crane body and the traveling
means; a movable connecting mechanism which connects the crane body
to the traveling means while allowing the relative displacement of
the crane body, which attempts to remain at the original position
by the inertia force acting on the crane body when the traveling
means vibrates transversely due to the occurrence of an earthquake,
with respect to the traveling means and a damper for restraining a
relative displacement between the crane body and the traveling
means, which is effected via the spring mechanism, are interposed
between the crane body and the traveling means; and the movable
connecting mechanism comprises a fist swing bearing ring consisting
of a lower ring mounted horizontally on the side of the traveling
means and an upper ring engaging concentrically with the lower ring
so as to be rotatable relatively, a horizontal beam provided
integrally with the upper ring of the first swing bearing ring, a
second swing bearing ring consisting of a lower ring mounted on the
upper face of the horizontal beam so as to have the rotation
centerline at a position shifted horizontally from the rotation
centerline of the first swing bearing ring and an upper ring
engaging concentrically with the lower ring so as to be rotatable
relatively, and a crane body connecting portion for connecting the
upper ring of the second swing bearing ring to the lower part of
the crane body.
[0049] In the above-described seismic isolation system for a crane
in accordance with the present invention, in the movable connecting
mechanism for connecting the crane body to the traveling means, the
horizontal beam is provided in place of the inclined beam.
Therefore, the relative movement caused between the traveling means
and the crane body by the cooperative action of the horizontal beam
and the first and second swing bearing rings below and above the
horizontal beam when an earthquake occurs is effected only in the
horizontal plane. The steady positional relationship between the
traveling means and the crane body is kept by the spring mechanism,
and the relative movement of the crane body and the traveling
means, which is effected via the spring mechanism when an
earthquake occurs, is relaxed by the damper. Thus, the seismic
isolation function for the crane body is fulfilled properly while
the seismic energy is absorbed.
[0050] In this case as well, the load of the crane body is
supported without a difficulty through the first swing bearing ring
on the side of the traveling means, the horizontal beam at the
middle part, and the second swing bearing ring on the side of the
crane body, and further through the crane body connecting
portion.
[0051] Further, in the seismic isolation system for a crane in
accordance with the present invention, a restraining mechanism,
which restrains the rotation of the horizontal beam at the normal
time and allows the rotation of the horizontal beam when the
restraint is released by the seismic force at the time of the
occurrence of an earthquake, is mounted between the horizontal beam
and the traveling means.
[0052] When the restraining mechanism such as a shear pin or a
brake is provided between the horizontal beam and the traveling
means so that the restraining mechanism is released only when an
earthquake occurs as described above, the horizontal beam is fixed
at the normal time, so that a stable operation is performed as in
the case of the conventional crane equipment.
[0053] As described in detail above, the seismic isolation system
for a crane in accordance with the present invention achieves the
following effects:
[0054] (1) The steady positional relationship between the crane
body and the traveling means are held by the restraining mechanism
at the normal time. When an earthquake occurs, the traveling means
is displaced transversely, and the crane body attempts to remain by
the inertia force. When the restraining mechanism is released by
the seismic force, a relative movement of the crane body and the
traveling means takes place, and the energy due to the relative
movement is absorbed by the energy absorbing means. the relative
movement (vibration) of the crane body and the traveling means is
properly relaxed by the damper mounted between the crane body and
the traveling means. Thus, the seismic isolation function is
fulfilled safely and properly. (Claim 1)
[0055] (2) The load of the crane body is transmitted from the
saddles installed to the crane body to the traveling means through
the crane load supporting block, the swing bearing, and the swing
bearing ring. An axial load, overturning load, and radial load
applied to the crane body by seismic vibrations during the
operation of the crane are supported by the swing bearing ring and
the swing bearing on the traveling means. An excitation force
applied in the radial direction perpendicular to the travel
direction of the traveling means acts on the lower ring of the
swing bearing ring on the traveling means so as to turn the swing
bearing, which is erected at an eccentric position from the center
of the swing bearing ring, around the vertical centerline of the
swing bearing ring together with the horizontal lever. This turning
force is automatically restrained by the horizontal lever swing
restoring mechanism provided between the horizontal lever and the
traveling means, whereby a damping operation against the excitation
force is performed. (Claim 2)
[0056] (3) When the guide rail for guiding the roller (or the
wheel) at the distal end of the horizontal lever mounted on the
swing bearing ring is provided so as to be inclined downward from
both sides thereof toward the rail middle position, which is the
neutral position, the operation in which the horizontal lever
having been swung by seismic vibrations is automatically restored
to the neutral position is performed properly when the roller
having been pushed against the guide rail by the gravity of the
crane body is automatically restored to the rail middle position.
Also, when the horizontal lever is swung by seismic vibrations, the
roller climbs the inclined face of the guide rail, so that the
swinging motion of the horizontal lever is restrained. (Claim
3)
[0057] (4) When the horizontal lever swing restoring mechanism is
composed of the laminated rubber mounted between the lower face of
the horizontal lever and the upper face of the traveling means, the
swinging motion of the horizontal lever is properly restrained by
the spring effect and damping effect of the laminated rubber
itself, and the operation in which the horizontal lever is
automatically restored to the swing amount zero position (neutral
position) is performed properly. (Claim 4)
[0058] (5) When the horizontal lever swing restoring mechanism is
composed of the coil spring mounted between the lower face of the
horizontal lever and the upper face of the traveling means, as
well, the swinging motion of the horizontal lever is elastically
restrained properly by the coil spring at the time of an earthquake
along with the operation of the antifriction guide member such as a
roller for guiding the horizontal lever in the lever swing
direction along the upper face of the traveling means. Also, the
operation in which the horizontal lever having been swung by
seismic vibrations is automatically restored to the neutral
position is performed properly by the automatic restoring function
of the coil spring. (Claim 5)
[0059] (6) When the braking means for braking the swinging motion
of the horizontal lever is provided, an active damping operation is
performed when an earthquake occurs. (Claim 6)
[0060] (7) The operation in which the swinging motion of the
horizontal lever is restrained is performed sufficiently even by
the use of such a damper (vibration exciter), whereby the operation
for actively damping the crane body can be performed when seismic
vibrations occur. (Claim 7)
[0061] (8) When there are provided the laminated rubber mounted
between the lower face of the crane body and the central portion of
the traveling means and the transverse slide mechanisms amounted
between the lower face of the crane body and the upper face of the
traveling means at longitudinally symmetrical positions with
respect to the laminated rubber, the crane body slides transversely
while supporting a bending moment by using the transverse slide
mechanisms when a transverse excitation force is applied to the
crane body by an earthquake. At this time, the sliding force
between the crane body and the traveling means is absorbed by the
deflection of the laminated rubber, and the crane body is
automatically restored to the normal position with respect to the
traveling means by the restoring force of the laminated rubber.
(Claim 8)
[0062] (9) When the oil damper for restraining the transverse slide
amount is mounted between the crane body and the traveling means,
the transverse movement of the crane body is restrained properly
when seismic vibrations occur, along with the operation in which
the transverse slide amount is restrained by the oil damper. (Claim
9)
[0063] (10) Vibrations of the crane body with respect to the
traveling means are detected by the vibration detecting sensor and
taken in the vibration control section when seismic vibrations
occur, and the driving means is controlled by the control signal
sent from the control section so that the crane body is isolated
from the vibrations of the traveling means. Thereby, the transverse
vibrations of the crane body caused by an earthquake are damped
actively. (Claim 10)
[0064] (11) When the lower part of the crane body and the upper
center of the traveling means are connected to each other by the
universal joint mechanism, and the vibration damping mechanisms,
which connect the crane body to the traveling means, are interposed
at positions on both sides of the universal joint mechanism, a
transverse excitation force applied to the crane body
perpendicularly to the travel direction by seismic vibrations is
absorbed as vibrations with a long vibration period by the turning
motion of the crane body around the longitudinal horizontal axis in
the universal joint mechanism. (Claim 11)
[0065] (12) When the vibration damping mechanisms, which connect
the crane body to the traveling means, are interposed at
longitudinally symmetrical positions with respect to the universal
joint mechanism, a longitudinal excitation force applied to the
crane body by seismic vibrations is also damped properly. (Claim
12)
[0066] (13) When the universal joint mechanism comprises saddles
projecting downward from the lower part of the crane body, a
universal joint block whose upper part is pivotally mounted to the
saddles via a shaft in the travel direction, and a lower pivotally
mounting portion which pivotally mounts the lower part of the
universal joint block to a bearing on the traveling means via a
horizontal transverse shaft, the construction of the universal
joint mechanism is compact and has a high strength, and the
arrangement thereof is effected properly. (Claim 13)
[0067] (14) When there are provided the laminated rubber mounted
between the lower face of the crane body and the central portion of
the traveling means and the turnover preventive restraining members
interposed between the lower face of the crane body and the upper
face of the traveling means at positions on both sides of the
laminated rubber, a transverse relative displacement produced
between the crane body and the traveling means by an earthquake is
absorbed by the spring effect and the friction damping due to the
deformation of the laminated rubber. At the same time, the
overturning moment load applied along with the transverse radial
load is supported by the resisting force of the turnover preventive
restraining members on both sides, and the restoring operation to
the deflection zero position is performed properly by the restoring
force of the laminated rubber. (Claim 14)
[0068] (15) When the laminated rubber and the turnover preventive
restraint members on both sides of the laminated rubber are
provided, and also the trigger mechanism is provided between the
crane body and the traveling means, the trigger mechanism is
released when an excitation force exceeding the given value is
applied to the crane by an earthquake, and the seismic isolation
function is fulfilled by the laminated rubber and the turnover
preventive restraining members on both sides of the laminated
rubber. In the normal state in which no earthquake occurs, the
crane body and the traveling means are connected to each other
integrally by the trigger mechanism, so that the rigidity of the
whole crane is maintained. (Claim 15)
[0069] (16) The load of the crane body is supported via the first
swing bearing on the side of the traveling means, the inclined beam
at the middle part, and the second swing bearing ring on the side
of the crane body, and further via the crane body connecting
portion. When the traveling means moves in the transverse direction
together with the rail at the time of the occurrence of earthquake,
since the first swing bearing ring and the second swing bearing
ring have the mutually shifted respective rotation centerlines, the
crane body attempts to remain by the inertia force and shifts
transversely relative to the traveling means. Accordingly, the
inclined beam is swung and pushes up the crane body in cooperation
with the second swing bearing ring on the beam. Thus, the crane
body mainly moves vertically due to the reciprocating transverse
movement of the traveling means caused by an earthquake, so that
the period of the crane body is made long, and the seismic
isolation function is fulfilled. (Claim 16)
[0070] (17) When the upper ring of the second swing bearing ring
and the crane body are connected to each other by the hinge pin
type connecting member and the hydraulic cylinder so that the
inclination is adjustable, the crane body can be kept horizontal by
the extending/contracting adjustment of the hydraulic cylinder
according to the face angle of the inclined beam, and the relative
relationship of the crane body with the second swing bearing ring
can be fixed properly. (Claim 17)
[0071] (18) When the restraining mechanism such as a shear pin or a
brake is provided between the inclined beam and the traveling means
so that the restraining mechanism is released only when an
earthquake occurs, the inclined beam is fixed at the normal time,
so that a stable operation is performed as in the case of the
conventional crane equipment. When the restraining mechanism is
released by the seismic force and the inclined beam is turned
reciprocatively, since the oil damper is provided to restrain the
turning of the inclined beam, the seismic energy is absorbed while
the relative movement of the crane body and the traveling means is
relaxed properly. (Claim 18)
[0072] (19) In the movable connecting mechanism for connecting the
crane body to the traveling means, the horizontal beam is provided
in place of the inclined beam. Therefore, the relative movement
caused between the traveling means and the crane body by the
cooperative action of the horizontal beam and the first and second
swing bearing rings below and above the horizontal beam when an
earthquake occurs is effected only in the horizontal plane. The
steady positional relationship between the traveling means and the
crane body is kept by the spring mechanism, and the relative
movement of the crane body and the traveling means, which is
effected via the spring mechanism when an earthquake occurs, is
relaxed by the oil damper. Thus, the seismic isolation function for
the crane body is fulfilled properly while the seismic energy is
absorbed. In this case as well, the load of the crane body is
supported without a difficulty through the first swing bearing ring
on the side of the traveling means, the horizontal beam at the
middle part, and the second swing bearing ring on the side of the
crane body, and further through the crane body connecting portion.
(Claim 19)
[0073] (20) When the restraining mechanism such as a shear pin or a
brake is provided between the horizontal beam and the traveling
means so that the restraining mechanism is released only when an
earthquake occurs, the horizontal beam is fixed at the normal time,
so that a stable operation is performed as in the case of the
conventional crane equipment. (Claim 20)
BRIEF DESCRIPTION OF THE DRAWINGS
[0074] FIG. 1 is a side view of a seismic isolation system for a
crane in accordance with a first embodiment of the present
invention;
[0075] FIG. 2 is a view taken in the direction of the arrows along
the line II-II of FIG. 1;
[0076] FIG. 3 is a view taken in the direction of the arrows along
the line III-III of FIG. 1;
[0077] FIG. 4 is an enlarged sectional view taken in the direction
of the arrows along the line IV-IV of FIG. 3;
[0078] FIG. 5 is an enlarged view taken in the direction of the
arrows along the line V-V of FIG. 1;
[0079] FIG. 6 is a view taken in the direction of the arrows along
the line VI-VI of FIG. 5;
[0080] FIG. 7 is an explanatory view showing a modification of an
essential portion of the system shown in FIG. 1;
[0081] FIG. 8 is a side view of a seismic isolation system for a
crane in accordance with a second embodiment of the present
invention;
[0082] FIG. 9 is a view taken in the direction of the arrows along
the line IX-IX of FIG. 8;
[0083] FIG. 10 is a block diagram of a control system provided for
the seismic isolation systems for a crane shown in FIGS. 1 and
8;
[0084] FIG. 11 is a side view of a seismic isolation system for a
crane in accordance with a third embodiment of the present
invention;
[0085] FIG. 12 is a sectional view taken in the direction of the
arrows along the line XII-XII of FIG. 11;
[0086] FIG. 13 is a sectional view taken in the direction of the
arrows along the line XIII-XIII of FIG. 11;
[0087] FIG. 14 is a side view of a seismic isolation system for a
crane in accordance with a fourth embodiment of the present
invention;
[0088] FIG. 15 is a sectional view taken in the direction of the
arrows along the line XV-XV of FIG. 14;
[0089] FIG. 16 is a sectional view taken in the direction of the
arrows along the line XVI-XVI of FIG. 14;
[0090] FIG. 17 is a front view of a traveling portal crane;
[0091] FIG. 18 is a side view of the traveling portal crane shown
in FIG. 17;
[0092] FIG. 19 is a perspective view of a seismic isolation system
for a crane in accordance with a fifth embodiment of the present
invention;
[0093] FIG. 20 is a side view of the seismic isolation system for a
crane shown in FIG. 19;
[0094] FIG. 21 is a view taken in the direction of the arrows along
the line A-A of FIG. 20;
[0095] FIG. 22 is a side view showing a modification of the seismic
isolation system for a crane shown in FIG. 20;
[0096] FIG. 23 is a perspective view of a seismic isolation system
for a crane in accordance with a sixth embodiment of the present
invention;
[0097] FIG. 24 is a side view of a conventional overhead traveling
crane; and
[0098] FIG. 25 is an enlarged front view of an essential portion of
the crane shown in FIG. 24.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0099] Embodiments of the present invention will now be described
with reference to the accompanying drawings. FIG. 1 is a side view
showing a state in which a seismic isolation system for a crane in
accordance with a first embodiment of the present invention is
provided between one traveling means provided at each of four
corners of a crane body of a portal crane and the crane body. FIG.
2 is a view taken in the direction of the arrows along the line
II-II of FIG. 1, FIG. 3 is a view taken in the direction of the
arrows along the line III-III thereof, FIG. 4 is an enlarged
sectional view taken in the direction of the arrows along the line
IV-IV of FIG. 3, FIG. 5 is an enlarged view taken in the direction
of the arrows along the line V-V of FIG. 1, and FIG. 6 is a view
taken in the direction of the arrows along the line VI-VI of FIG.
5.
[0100] The crane equipped with the seismic isolation system of this
embodiment is constructed as a portal crane as shown in FIGS. 17
and 18, and is provided with a seismic isolation system 10 as shown
in FIG. 1 between a portal crane body 1 and traveling means 2 at
each of four corners thereof.
[0101] Specifically, as shown in FIG. 1, the traveling means 2
comprises four sets of tracks 4 each provided with two wheels 5
which travel on a rail 3, two sets of lower equalizer beams 6 each
of which connects the adjacent two sets of tracks 4, 4 by using
shafts 7, and an upper equalizer beam 8 which connects two sets of
lower equalizer beams 6 by using shafts 9, and a seismic isolation
system 10 of the first embodiment of the present invention is
mounted between the upper equalizer beam 8 and the crane body
1.
[0102] In FIG. 1, reference numeral C1 denotes the centerline of
the upper equalizer beam 8, and C2 denotes a position at which the
seismic isolation system 10 is installed to the upper equalizer
beam 8, which shifts toward the center of the crane body 1 through
a fixed distance from the centerline C1.
[0103] The traveling means 2 of the portal crane is of types of
various combinations in terms of the number of wheels which is
different from the above description. Also, one set of the track 4
with two wheels is sometimes provided at each corner of the crane
body 1. In the embodiments of the present invention, for each type
of these traveling means 2, the seismic isolation system 10 is
provided so as to connect the uppermost equalizer beam or track of
the traveling means 2 to saddles 11 on the crane body 1.
[0104] As shown in FIGS. 1 to 4, the seismic isolation system 10
has a swing bearing ring 12 consisting of a lower ring 31 and an
upper ring 32. The lower ring 31 is installed horizontally around
the vertical centerline C1 on the upper equalizer beam 8 of the
traveling means 2. The upper ring 32 engages concentrically with
the lower ring 31 via bearings 33 and 34 for axial load and moment
load and a bearing 35 for radial load so as to be rotatable
relatively.
[0105] Also, as shown in FIGS. 5 and 6, a lower vertical shaft 17
of a crane load supporting block 18 is supported on a vertical
shaft supporting swing bearing 13 provided along the centerline C1
at an eccentric position on the upper ring 32 of the swing bearing
ring 12. The block 18 is pivotally carried on the saddles 11
installed on the crane body 1 through a horizontal transverse shaft
16. In this manner, the traveling means 2 is pivotally supported by
the crane body 1 via the horizontal transverse shaft 16 as shown in
FIG. 1.
[0106] The seismic isolation system 10 supports a horizontal
transverse shaft 14, which is disposed in a direction along the
diametric direction of the swing bearing ring 12 and meeting the
centerline C2, via brackets 15 on the upper ring 32, and has a
horizontal lever 19 supported by the horizontal transverse shaft
14. A horizontal lever swing restoring mechanism 20 is provided as
shown in FIGS. 1 to 3, which automatically restores the position of
the horizontal lever 19 to its neutral position (position along the
crane traveling direction) while supporting the distal end of the
horizontal lever 19 so that the distal end of the horizontal lever
19 is swung around the vertical centerline C2 of the swing bearing
ring 12 together with the upper ring 32.
[0107] Specifically, a roller (including the case of a wheel) 24 is
provided at the distal end of the horizontal lever 19, which roller
24 can rotate freely along the swing direction around the swing
centerline C2 of the horizontal lever. Also, a guide rail 25 is
provided on the upper equalizer beam 8 of the traveling means 2 to
guide the roller 24. The guide rail 25 is inclined downward toward
the middle position of the rail, which is the neutral position (see
FIG. 2).
[0108] Also, an auxiliary driving type (or driven type) hydraulic
damper 21 is provided between the upper ring 32 of the swing
bearing ring 12 and the equalizer beam 8, and a drive unit 21a for
the hydraulic damper 21 is provided.
[0109] Further, a braking plate 22 is provided on the side opposite
to the horizontal lever 19 on the upper ring 32 of the swing
bearing ring 12, and detachable brakes 23 are mounted on the
braking plate 22. This constitutes braking means for braking the
swinging motion of the horizontal lever 19.
[0110] The swing bearing 13 can be replaced with a small swing
bearing ring similar to the swing bearing ring 12 to support the
lower vertical shaft 17 of the load supporting block 18.
[0111] The horizontal lever swing restoring mechanism 20 can use a
construction such that a laminated rubber 26 for damping vibrations
as shown in FIG. 7, which has generally been used to damp seismic
vibrations of buildings, is provided between the lower face of the
horizontal lever 19 and the upper face of the upper equalizer beam
8 in place of the combined construction of the roller 24 and the
guide rail 25. Further, a coil spring can be used in place of the
laminated rubber 26, and besides restoring means of any other
construction can be used.
[0112] When the coil spring is used in place of the laminated
rubber 26, a roller or a sliding bearing member, serving as an
antifriction guide member, is additionally used to guide the
horizontal lever 19 so that the distal end of the lever 19 is
guided along the upper face of the traveling means 2, that is, the
upper face of the upper equalizer beam 8.
[0113] The above-described seismic isolation system 10 is kept in a
state in which the braking plate 22 is locked by the brakes 23
during the operation of the crane, and the brakes 23 are released
when the operation of the crane is suspended, by which the seismic
isolation system 10 can be kept in an operable state. It is
preferable that the locking of the braking plate 22 by the brakes
23 can be released in response to an earthquake detection signal
sent from a vibration detecting sensor (not shown) during the
operation of the crane.
[0114] The load of the portal crane body 1 is transmitted from
saddles 11 at four corners of the portal crane body 1 to the
traveling means 2 including the upper equalizer beam 8 through the
load supporting block 18, the swing bearing 13, and the swing
bearing ring 12.
[0115] The excitation forces of axial load A, overturning moment
loads M, M', and radial load R, which are applied to the portal
crane body 1 by seismic vibrations during the operation of the
crane, are absorbed by the swing bearing ring 12 on the traveling
means 2 and the swing bearing 13.
[0116] At this time, the excitation force R applied in the radial
direction perpendicular to the rail 3 acts so as to turn the swing
bearing 13 eccentrically disposed from the swing bearing ring 12 of
the traveling means 2 around the center of the swing bearing ring
12 together with the horizontal lever 19. This turning force is
restrained by the horizontal lever swing restoring mechanism 20
provided between the horizontal lever 19 and the traveling means 2,
whereby damping is achieved.
[0117] Since the horizontal lever swing restoring mechanism 20 is
composed of the roller 24 provided at the distal end of the
horizontal lever 19 shown in FIGS. 1 to 3 and a guide rail 25
inclined downward toward the middle position on the traveling means
2, the roller 24 moves on the face of the guide rail 25 in the
downwardly inclined direction when the horizontal lever 19 is
swung, so that the movement force is restrained, and the horizontal
lever 19 returns to the middle position of the guide rail 25
automatically by means of the gravity of the crane.
[0118] When the horizontal lever restoring mechanism 20 is composed
of the laminated rubber 26 shown in FIG. 7, the movement force of
the horizontal lever 19 is restrained by the spring element,
friction damping element, and viscosity damping element of the
laminated rubber 26 itself, and then the horizontal lever 19
returns automatically to the turning amount zero position. When the
coil spring is used in place of the laminated rubber 26, the
movement force of the horizontal lever 19 is restrained by the
spring element of the coil spring itself, and then the horizontal
lever 19 returns automatically to the turning amount zero
position.
[0119] Also, impulsive turning of the horizontal lever 19 caused by
an earthquake can be restrained by the auxiliary hydraulic damper
21 as well. By using the driving type hydraulic damper 21, seismic
vibrations can be damped actively. Further, since the braking means
22, 23 for restraining the swinging motion of the horizontal lever
19 is provided, the operation for damping earthquakes can be
performed more properly.
[0120] The above-described operation is performed independently at
the portion of traveling means 2 at four corners of the portal
crane body, so that the seismic force acting on the portal crane
can be absorbed safely by the traveling means 2.
[0121] Also, this configuration can provide a seismic isolation
mechanism that can safely absorb a great horizontal swing torsion
of a large portal crane body 1 by using a compact mechanism.
[0122] Further, since the seismic isolation system 10 consists of
an independent mechanism disposed between the traveling means 2 and
the saddles 11, maintenance, adjustment, and repair work can be
done easily.
[0123] Next, a seismic isolation system for a crane in accordance
with a second embodiment of the present invention will be
described. FIG. 8 is a side view of the seismic isolation system,
and FIG. 9 is a view taken in the direction of the arrows along the
line IX-IX of FIG. 8.
[0124] In this second embodiment, on a traveling portal crane
equipped with a portal crane body 1 and traveling means 2, similar
to those in the above-described first embodiment, a seismic
isolation system 10, which is interposed between the crane body 1
and the traveling means 2, is constructed as described below.
[0125] In this system, a laminated rubber 36 is mounted between the
lower face of the crane body 1 and the central portion of an upper
equalizer beam 8 of the traveling means 2, and a transverse slide
mechanisms 37 are mounted at longitudinally symmetrical positions
with respect to the laminated rubber 36 between the lower face of
the crane body 1 and the upper face of the upper equalizer beam 8.
Also, a hydraulic damper 38 for damping vibrations is provided
between the slide portion of the crane body 1 and the upper
equalizer beam 8.
[0126] As the laminated rubber 36, a laminated rubber having a
necessary height and diameter is used to accommodate a transverse
displacement occurring between the crane body 1 and the traveling
means 2 when seismic vibrations occur.
[0127] The transverse slide mechanism 37 is composed of a rail 39
having a T-shaped cross section, which is fixed onto the upper
equalizer beam 8, and four rollers 41, which are mounted on each of
a pair of saddles 40 extending along both sides of the rail 39 from
the crane body 1 and rotate while contacting with the upper and
lower faces of the rail 39. The hydraulic damper (vibration
exciter) 38 is provided in the transverse direction between the
saddle 40 and the upper equalizer beam 8, and a drive unit 38a for
the hydraulic damper 38 is provided.
[0128] In the above-described second embodiment, when the
transverse excitation force R is applied to the crane by an
earthquake, the crane body 1 slides transversely while the
overturning bending moment load M is absorbed by the paired
transverse slide mechanisms 37.
[0129] At this time, the mutual side forces are absorbed by the
deflection of the laminated rubber 36, and the crane body 1 and the
traveling means 2 are restored automatically to the slide zero
position by the restoring force of the laminated rubber 36.
[0130] Also, at this time, the hydraulic damper 38 operates in
parallel so as to damp the mutual slide forces. Other operation and
effects are the same as in the case of the first embodiment.
[0131] The following is a description of a control system provided
for the seismic isolation systems for a crane of the
above-described first and second embodiments. As shown in FIG. 10,
there are provided a vibration detecting sensor 42 mounted on the
traveling means 2 and or the crane body 1 of the first and second
embodiments, the drive unit 21a for the hydraulic damper 21 (FIG.
1) or the drive unit 38a for the hydraulic damper 38 (FIG.8), and a
vibration control section 43 for controlling a drive unit for the
roller or wheel 24.
[0132] In the seismic isolation systems of the above-described
first and second embodiments, mutual vibrations of the traveling
means 2 and the crane body 1 caused by an earthquake are detected
by the vibration detecting sensor 42, and are taken in the
vibration control section 43. The vibration control section 43
controls the drive unit 21a or 38a to restrain the velocity
displacement, by which the transverse vibrations of the portal
crane caused by an earthquake can be damped actively, so that the
derailment etc. can be prevented.
[0133] Next, a seismic isolation system for a crane in accordance
with a third embodiment of the present invention will be described.
FIG. 11 is a side view of the seismic isolation system, FIG. 12 is
a sectional view taken in the direction of the arrows along the
line XII-XII of FIG. 11, and FIG. 13 is a sectional view taken in
the direction of the arrows along the line XIII-XIII of FIG.
11.
[0134] In this third embodiment as well, like the above-described
embodiments, traveling means 2 is provided at each of four corners
of the crane body 1 of a portal crane. Specifically, as shown in
FIG. 11, the traveling means 2 comprises four sets of tracks 4 each
provided with two wheels 5 which travel on a rail 3, two sets of
lower equalizer beams 6 each of which connects the adjacent two
sets of tracks 4, 4 by using shafts 7, and an upper equalizer beam
8 which connects two sets of lower equalizer beams 6 by using
shafts 9, and a seismic isolation system 10 of this embodiment is
mounted between the upper equalizer beam 8 and the crane body
1.
[0135] As shown in FIGS. 11 to 13, the seismic isolation system 10
has a universal joint mechanism 111 for connecting the lower
portion of the crane body 1 to the center of the upper equalizer
beam 8 at the upper part of the traveling means 2, and also has
compression springs 113 and hydraulic dampers 114, which serve as a
vibration damping mechanism 112 which connects the crane body 1 to
the traveling means 2 at positions on both sides of the universal
joint mechanism 111. As the vibration damping mechanism 112, an
elastic rubber type mechanism or a hydraulic cylinder type
mechanism is alternatively used, and a mechanism of any type can be
used.
[0136] The universal joint mechanism 111 has saddles 115 projecting
downward from the lower part of the crane body 1, and a universal
joint block 119 whose upper part is pivotally mounted to the
saddles 115 via a shaft 117 disposed in the travel direction. The
universal joint mechanism also has a lower pivotally mounting
portion for pivotally mounting the lower part of the block 119 to a
bearing 116 on the traveling means 2 via a horizontal transverse
shaft 118.
[0137] The configuration may be such that the shaft 117 is replaced
with a horizontal transverse shaft, and the horizontal transverse
shaft 118 is replaced with a shaft disposed in the travel
direction.
[0138] On the above-described crane equipped with the seismic
isolation system 10, the vibration damping mechanisms 112 provided
on both sides of the universal joint mechanism 111 are balanced
mutually to keep the universal joint block 119 vertical at the
normal time. In this state, the weight of the crane is transmitted
as the axial load A from the four corners of the crane body 1 to
the traveling means 2 through the universal joint mechanism
111.
[0139] The axial load A, the overturning moment load M, and the
radial load R, which are applied to the crane body 1 in operation
by seismic vibrations, are also transmitted similarly to between
the traveling means 2 and the crane body 1 through the universal
joint mechanism 111.
[0140] At this time, the excitation forces of the radial load R and
the axial load A applied to the crane in the transverse direction
perpendicular to the rail 3 by seismic vibrations are absorbed as
vibrations with a long vibration period by the motion of the
universal joint block 119 which turns around the shaft 117 parallel
with the travel direction while being damped by the elastic
resistance of the compression springs 113 and the hydraulic dampers
114, which serve as the vertical vibration damping mechanism 112,
on the traveling means 2.
[0141] At this time, the transverse relative displacement between
the traveling means 2 and the crane body 1 is given by the
inclination of the crane body 1 with the shaft 117 of the universal
joint mechanism 111 being the center, and the absorption of
displacement and the holding of the position are given by the
vertical extension and contraction of the compression springs 113
and the hydraulic dampers 114 of the vibration damping mechanism
112.
[0142] Therefore, for vibrations with a long natural period of
portal crane caused by an earthquake, the seismic vibrations can be
absorbed and damped safely by a large displacement of the seismic
isolation system 10.
[0143] As shown in FIGS. 17 and 18, when a torsional load S is
applied by different radial loads R applied to the traveling means
2 at four corners of the crane body 1, the above-described
operation takes place independently at each portion of the
traveling means 2, so that the seismic isolation system 10 operates
longitudinally and transversely with different displacement for
each portion of the traveling means 2, by which the torsional load
S can be absorbed safely on each traveling means 2.
[0144] Further, by arranging the springs and dampers at
longitudinally symmetrical positions with respect to the universal
joint mechanism 111, the same effect can be achieved for the
seismic vibrations in the travel direction.
[0145] Also, according to the seismic isolation system of this
construction, the hydraulic damper 114 is configured so as to be
controllable, by which seismic vibrations can be damped
actively.
[0146] Further, this configuration can provide a seismic isolation
mechanism that can safely absorb a great horizontal swing torsion
of a large portal crane body 1 by using a compact mechanism.
[0147] Also, since the seismic isolation system 10 consists of an
independent mechanism disposed between the traveling means 2 and
the crane body 1, maintenance, adjustment, and repair work can be
done easily.
[0148] Next, a seismic isolation system for a crane in accordance
with a fourth embodiment of the present invention will be
described. FIG. 14 is a side view of the seismic isolation system,
FIG. 15 is a sectional view taken in the direction of the arrows
along the line XV-XV of FIG. 14, and FIG. 16 is a sectional view
taken in the direction of the arrows along the line XVI-XVI of FIG.
14.
[0149] In this fourth embodiment as well, as shown in FIG. 14, like
the above-described embodiments, traveling means 2 is provided at
each of four corners of the crane body 1 of a portal crane.
Specifically, as shown in FIG. 14, the traveling means 2 comprises
four sets of tracks 4 each provided with two wheels 5 which travel
on a rail 3, two sets of lower equalizer beams 6 each of which
connects the adjacent two sets of tracks 4, 4 by using shafts 7,
and an upper equalizer beam 8 which connects two sets of lower
equalizer beams 6 by using shafts 9, and a seismic isolation system
10 of this embodiment is mounted between the upper equalizer beam 8
and the crane body 1.
[0150] As shown in FIGS. 14 to 16, the seismic isolation system 10
is composed of a laminated rubber 211 mounted between the lower
face of the crane body 1 and the central portion of the traveling
means 2 (the central portion of the upper equalizer beam 8), and
compression springs 212 serving as a turnover preventive
restraining member which are interposed between the lower face of
the crane body 1 and the upper face of the upper equalizer beam 8
at positions on both sides of the laminated rubber 211.
[0151] Also, a trigger mechanism 213 for restraining the horizontal
relative displacement between the crane body 1 and the traveling
means 2 is provided between the crane body 1 and the traveling
means 2.
[0152] As the trigger mechanism 213, a shear pin type, a holding
brake type, or a wedge-pin type can be used. Further, a cam roller
type, which is released and driven by an earthquake detecting
sensor, can also be used.
[0153] As the laminated rubber 211, a laminated rubber, which has a
height and diameter enough to accommodate a transverse displacement
occurring between the crane body 1 and the traveling means 2 when
seismic vibrations occur, is used.
[0154] On the above-described crane equipped with the seismic
isolation system 10, the horizontal force is kept by the trigger
mechanism 213 and the compression springs provided on both sides of
the laminated rubber 211 are balanced mutually at the normal time,
by which the laminated rubber 211 is kept transversely neutral.
[0155] In this state, the weight of the crane is transmitted as the
axial load A from the four corners of the portal crane body 1 to
the traveling means 2 through the laminated rubber 211 and the
compression springs 212.
[0156] The excitation forces of the axial load A, the overturning
moment load M, and the radial load R, which are newly applied to
the portal crane in operation by seismic vibrations, are also
transmitted similarly to between the traveling means 2 and the
crane body 1 through the compression springs 212 on both sides of
the laminated rubber 211.
[0157] When a transverse excitation force exceeding a given value
is applied to the portal crane by an earthquake, the trigger
mechanism 213 is released, and a transverse relative displacement
caused between the crane body 1 and the traveling means 2 by the
radial load R is absorbed by the spring element and the friction
damping due to the deformation of the laminated rubber 211. At the
same time, the overturning moment load M applied along with the
transverse radial load R is supported by the resisting force of the
compression springs 212 on both sides, and the restoring operation
to the deflection zero position is performed by the restoring force
of the laminated rubber 211 and the compression springs 212.
[0158] When an excitation force in the travel direction is applied
to the crane by an earthquake, the relative displacement in the
travel direction occurring between the crane body 1 and the
traveling means 2 is absorbed by the slip between the traveling
means 2 and the rail 3, the deflection in the travel direction of
the laminated rubber 211, and the restoring force, so that the
deflection zero position is restored.
[0159] Therefore, vibrations with a long period occurring on the
portal crane can be absorbed and damped safely by a large
displacement of the laminated rubber 211 and the compression
springs 212.
[0160] Since the above-described operation takes place
independently at each portion of the traveling means 2 at four
corners of the portal crane body 1, the seismic force acting on the
portal crane can be absorbed safely on each traveling means 2. When
a torsional load S is applied to the crane body 1 by the
application of different radial loads R, the above-described
operation takes place independently at each portion of the
traveling means 2, so that the laminated rubber 211 and the
compression springs 212 operate longitudinally and transversely
with different displacement for each portion of the traveling means
2, by which the torsional load S can be absorbed safely on each
traveling means 2.
[0161] In the seismic isolation system thus configured, by
additionally providing a hydraulic damper in the travel direction
or transverse direction between the crane body 1 and the traveling
means 2, the vibration damping effect can further be enhanced.
[0162] Further, this configuration can provide a seismic isolation
mechanism that can safely absorb a great horizontal swing torsion
of a large portal crane body 1 by using a compact mechanism.
[0163] Also, since the seismic isolation system 10 consists of an
independent simple mechanism disposed between the traveling means 2
and the crane body 1, maintenance, adjustment, and repair work can
be done easily.
[0164] As turnover preventive restraining members arranged on both
sides of the laminated rubber 211, link type members can be used in
place of the compression springs 212. Specifically, a link
mechanism can be used in which the lower end of a link is pivotally
supported on the upper equalizer member 8 by a longitudinal pin,
and the upper end thereof is pivotally supported by a longitudinal
pin in a convex arcuate guide hole formed at the upper part of a
bracket installed along the transverse direction on the lower face
of the crane body 1.
[0165] Next, a seismic isolation system for a crane in accordance
with a fifth embodiment of the present invention will be described.
FIG. 19 is a perspective view showing a schematic construction of
the seismic isolation system, FIG. 20 is a side view of the seismic
isolation system, FIG. 21 is a view taken in the direction of the
arrows along the line A-A of FIG. 20, and FIG. 22 is a side view
showing a modification of an essential portion of the seismic
isolation system.
[0166] The crane equipped with the seismic isolation system of this
embodiment is also constructed as a portal crane as shown in FIGS.
17 and 18, and a seismic isolation system 10 is provided between a
portal crane body 1 and traveling means 2 provided at four corners
thereof as shown in FIGS. 20 and 21.
[0167] Specifically, as shown in FIG. 20, the traveling means 2
comprises four sets of tracks 4 each provided with two wheels 5
which travel on a rail 3, two sets of lower equalizer beams 6 each
of which connects the adjacent two sets of tracks 4, 4 by using
shafts 7, and an upper equalizer beam 8 which connects two sets of
lower equalizer beams 6, 6 by using shafts 9, and the seismic
isolation system 10 in accordance with the fifth embodiment is
mounted between the upper equalizer beam 8 and the crane body
1.
[0168] In this embodiment, a first swing bearing ring 51 is
provided, via a base member 51a having an inclined support face, on
a bed member 61 pivotally mounted at the center of the upper
equalizer beam 8 by using a transverse shaft 50 so as to be
inclined downward in the travel direction.
[0169] The first swing bearing ring 51 has a construction similar
to that of the swing bearing ring 12 shown in FIG. 4. Specifically,
a lower ring of the first swing bearing ring 51 is fixed to the
base member 51a, and an upper ring thereof is fixed to an inclined
beam 60.
[0170] The rotation centerline C2 of the upper ring and the lower
ring of the first swing bearing ring 51, which can be rotated
relatively, is inclined, and a second swing bearing ring 52 having
the same construction as that of the first swing bearing ring 51 is
provided on the upper face of the inclined beam 60, whose rotation
centerline C1 is shifted horizontally from the rotation centerline
C2. Specifically, a lower ring of the second swing bearing ring 52
is fixed to the upper face of the inclined beam 60, and an upper
ring thereof is fixed to a mounting plate 52a.
[0171] A hinge pin type connecting member 160 including a spherical
bearing 160a and a plurality of hydraulic cylinders 54 are provided
as a crane body connecting portion for connecting the upper ring of
the second swing bearing ring 52 to the lower part of the crane
body 1 via the mounting plate 52a.
[0172] Each of the hydraulic cylinders 54 is adapted to absorb a
change in face angle caused when the inclined beam 60 rotates
around the rotation centerline C2 by being extended and contracted
in response to a detection signal sent from an inclined beam
rotational angle detecting sensor 56.
[0173] Also, the hydraulic cylinder 54 supports the moment load in
the transverse direction and the travel direction, and transfers
the moment load between the crane body 1 and the traveling means
2.
[0174] A shear pin 53 is provided between the inclined beam 60 and
the bed member 61 as a restraining mechanism. A steady relative
positional relationship between the crane body 1 and the traveling
means 2 is kept by the shear pin 53 at the normal time. When an
earthquake occurs, however, the steady relationship is broken off
by the cutting of the shear pin 53 caused by the seismic force, so
that a relative movement of the crane body 1 and the traveling
means 2 is allowed, by which the function of the seismic isolation
system 10 is fulfilled as described later.
[0175] Also, an oil damper 55 is mounted between the inclined beam
60 and the bed member 61 to absorb kinetic energy while regulating
the relative movement of the crane body 1 and the traveling means 2
when the seismic isolation system 10 is operating.
[0176] In the seismic isolation system of the above-described
embodiment, the load of the crane body 1 is supported through the
first swing bearing ring 51 on the side of the traveling means 2,
the inclined beam 60 at the middle part, and the second swing
bearing ring 52 on the side of the crane body 1, and further
through the hinge pin type connecting member 160 and the hydraulic
cylinders 54, serving as the crane body connecting portion.
[0177] When the shear pin 53 is cut at the time of the occurrence
of an earthquake, and the traveling means 2 moves in the transverse
direction as indicated by an arrow mark m in FIG. 19 together with
the rail 3, since the first swing bearing ring 51 and the second
swing bearing ring 52 have the mutually shifted respective rotation
centerlines, the crane body 1 attempts to remain by the inertia
force and shifts transversely relative to the traveling means 2.
Accordingly, the inclined beam 60 is swung around the rotation
centerline C2 as indicated by an arrow mark n in FIG. 19, and
pushes up the crane body 1 in cooperation with the second swing
bearing ring 52 on the beam 60. Thus, the crane body 1 mainly moves
vertically along with the reciprocating transverse movement of the
traveling means 2 caused by an earthquake, so that a restoring
force due to the gravity acts, by which the period of the crane
body 1 is made long.
[0178] Since the upper ring of the second swing bearing ring 52 and
the crane body 1 are connected to each other by the hinge pin type
connecting member 160 and hydraulic cylinders 54 so that the
inclination can be regulated, the crane body 1 can be kept
horizontal by adjusting the hydraulic cylinders 54 according to the
face angle of the inclined beam 60, so that the relative
relationship of the crane body 1 with respect to the second swing
bearing ring 52 can be established properly.
[0179] Further, since the restraining mechanism as the shear pin
(or the brake) 53 is provided between the inclined beam 60 and the
traveling means 2, and the restraining mechanism is released only
when an earthquake occurs, a stable operation is performed as in
the case of the conventional crane equipment. When the restraining
mechanism is released by the seismic force and the inclined beam 60
is turned reciprocatively, since the oil damper 55 is provided to
absorb kinetic energy while restraining the turning of the inclined
beam 60, the seismic energy is absorbed while the relative movement
of the crane body 1 and the traveling means 2 is relaxed
properly.
[0180] In a modification of the fifth embodiment shown in FIG. 22,
the second swing bearing ring 52 is kept horizontal by being
mounted via a base member 52b whose bottom face is inclined with
respect to the inclined beam 60, but other constructions are the
same as those of the system shown in FIG. 20, and almost the same
operation and effects as those of the system of the fifth
embodiment can be achieved.
[0181] Next, a seismic isolation system for a crane in accordance
with a sixth embodiment of the present invention will be described.
FIG. 23 is a perspective view showing an essential portion of the
seismic isolation system. The crane equipped with the seismic
isolation system of this embodiment is also constructed as a portal
crane as shown in FIGS. 17 and 18, and a seismic isolation system
10 is provided between a portal crane body 1 and traveling means 2
provided at four corners thereof as shown in FIG. 23.
[0182] Specifically, as shown in FIG. 23, the traveling means 2
comprises four sets of tracks 4 each provided with two wheels 5
which travel on a rail 3, two sets of lower equalizer beams 6 each
of which connects the adjacent two sets of tracks 4, 4 by using
shafts 7, and an upper equalizer beam 8 which connects two sets of
lower equalizer beams 6, 6 by using shafts 9, and the seismic
isolation system 10 in accordance with the sixth embodiment is
mounted between the upper equalizer beam 8 and the crane body
1.
[0183] In this embodiment, a first swing bearing ring 51 is
provided in a horizontal state on a bed member 61 pivotally mounted
at the center of the upper equalizer beam 8 by using a transverse
shaft 50.
[0184] The first swing bearing ring 51 has a construction similar
to that of the swing bearing ring 12 shown in FIG. 4. Specifically,
a lower ring of the first swing bearing ring 51 is fixed to a bed
member 61, and an upper ring thereof is fixed to a horizontal beam
62.
[0185] The rotation centerline C2 of the upper ring and the lower
ring of the first swing bearing ring 51, which can be rotated
relatively, is vertical, and a second swing bearing ring 52 having
the same construction as that of the first swing bearing ring 51 is
provided on the upper face of the horizontal beam 62, whose
rotation centerline C1 is shifted horizontally from the rotation
centerline C2. Specifically, a lower ring of the second swing
bearing ring 52 is fixed to the upper face of the horizontal beam
62, and an upper ring thereof is fixed to a mounting plate 52a.
[0186] An appropriate crane body connecting portion, such as bolts
and nuts, is provided to connect the upper ring of the second swing
bearing ring 52 to the lower part of the crane body 1 via the
mounting plate 52a.
[0187] A shear pin (or a brake) 53 is provided between the
horizontal beam 62 and the bed member 61 as a restraining
mechanism. A steady relative positional relationship between the
crane body 1 and the traveling means 2 is kept by the shear pin 53
at the normal time. When an earthquake occurs, however, the steady
relationship is broken off by the cutting of the shear pin 53
caused by the seismic force, so that the relative movement of the
crane body 1 and the traveling means 2 is allowed, by which the
function of the seismic isolation system 10 is fulfilled as
described later.
[0188] Also, an oil damper 55 is mounted between the horizontal
beam 62 and the bed member 61 to absorb kinetic energy while
regulating the relative movement of the crane body 1 and the
traveling means 2 when the seismic isolation system 10 is
operating.
[0189] Thus, the movable connecting mechanism composed of the first
swing bearing ring 51, the horizontal beam 62, the second swing
bearing ring 52, the bolts and nuts serving as the crane body
connecting portion, and the like is provided between the crane body
1 and the traveling means 2 to connect the crane body 1 to the
traveling means 2 while allowing the relative displacement of the
crane body 1, which attempts to remain at the original position by
the inertia force acting on the crane body 1, with respect to the
traveling means 2. Particularly, in the sixth embodiment, a spring
mechanism (coil spring) 63 is mounted between the crane body 1 and
the bed member 61 to elastically keep the steady positional
relationship between the crane body 1 and the traveling means
2.
[0190] In the above-described sixth embodiment, in the movable
connecting mechanism for connecting the crane body 1 to the
traveling means 2, the horizontal beam 62 is provided in place of
the inclined beam 60 in the fifth embodiment described before.
Therefore, the relative movement caused between the traveling means
2 and the crane body 1 by the cooperative action of the horizontal
beam 62 and the first and second swing bearing rings 51 and 52
below and above the horizontal beam 62 when an earthquake occurs is
effected only in the horizontal plane. The steady positional
relationship between the traveling means 2 and the crane body 1 is
kept by the spring mechanism 63, and the relative movement of the
crane body 1 and the traveling means 2, which is effected via the
spring mechanism 63 when an earthquake occurs, is relaxed by the
oil damper 55. Thus, the seismic isolation function for the crane
body 1 is fulfilled properly while the seismic energy is
absorbed.
[0191] In this embodiment as well, the load of the crane body 1 is
supported without a difficulty through the first swing bearing ring
51 on the side of the traveling means 2, the horizontal beam 62 at
the middle part, and the second swing bearing ring 52 on the side
of the crane body 1, and further through the crane body connecting
portion.
[0192] Further, since the restraining mechanism such as the shear
pin (or the brake) 53 is provided between the horizontal beam 62
and the traveling means 2, and the restraining mechanism is
released only when an earthquake occurs, the horizontal beam is
fixed at the normal time, so that a stable operation is formed as
in the case of the conventional crane equipment.
* * * * *