Partition wall panel

In a partition wall panel of the present invention, a panel is formed by arranging a plurality of plates at an interval in the direction of the thickness of the plates and by joining the plates along at least part of the peripheries of the plates or/and at part of the surfaces of the plates using a joint member, and a plurality of such panels are integrated while arranged side by side through a plurality of air layers, and connected along at least part of the peripheries thereof or/and at part of the surfaces thereof using a connecting member. As a result of this construction, a thin, light-weight, and highly sound-insulating multi-layered panel structure can be provided.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a multi-layered panel structure used as a 
partition wall for partitioning a large indoor space into several spaces. 
2. Description of the Related Art 
While partition walls are roughly divided in two types, fixed and movable, 
most of them are constructed by attaching face members, such as steel 
plates 12 and gypsum boards 13, to both surfaces of a metallic frame 
member 11, e.g., as shown in FIG. 18. 
In order to improve the sound insulation performance of such a partition 
wall, measures are taken to increase the thickness of the gypsum board or 
to attach two gypsum boards to one side of the frame member for increasing 
the mass per unit area of the face member. Further, in order to suppress 
the coincidence phenomenon in which sound insulation performance decreases 
at the frequency higher than critical coincidence frequency fc that is 
calculated by the equation (1) shown below from the mass per unit area: m 
and the bending rigidity B of a face member, an example is disclosed, in 
which a measure is taken to attach a damping material to the inner side of 
a face member (see Japanese Patent Laid-Open Application No. Hei 6-221061, 
being hereby fully incorporated by reference). 
EQU fc=(C.sup.2 /2.pi.).times.(m/B).sup.1/2 (1) 
where C is the velocity of sound in air. 
Further, in order to suppress the low-frequency resonance transmission 
phenomenon in which sound insulation performance decreases by the 
vibrations caused at one of two face members being transmitted to the 
other as a result of the air layer interposed between the two face members 
acting as a pneumatic spring, a measure is taken to use glass wool to fill 
in the space between the two face members (see, e.g., Japanese Utility 
Model Laid-Open Application No. Sho 51-154030, being hereby fully 
incorporated by reference). Still further, for a movable partition wall 
for which a high sound insulation performance is particularly required, 
there is an example in which two partition walls are installed about 1 m 
apart from each other. 
Although the sound insulation performance of a wall can be increased by 
increasing the mass per unit area of a face member, the wall becomes 
heavier and hard to install. Further, if the wall is of a movable type, it 
is hard to move the wall manually and thus entails much time and labor to 
set it up. Still further, even if the mass per unit areais, e.g., doubled, 
the sound insulation performance can be improved by 5 dB at most. 
On the other hand, when two partition walls, each exhibiting a sound 
insulation performance of, e.g., 30 dB at 500 Hz, are installed about 1 m 
apart from each other as a double-installed wall, a sound insulation 
performance of about 60 dB can be obtained. However, such double-installed 
wall design requires not only twice as large a space for installing the 
walls, but also twice as large ancillary facilities such as rails for 
moving the partition walls. Therefore, if sufficient installation space is 
not available or if there are restrictions on expenditure, such 
double-installed wall design cannot be adopted. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a thin, light-weight, and 
highly sound-insulating multi-layered panel structure. 
The present invention provides a partition wall panel which is constructed 
by using a panel formed by arranging a plurality of plates at an interval 
in the direction of the thickness of the plates and joining the plates 
along at least part of the peripheries of the plates or/and at part of the 
surfaces of the plates using a joint member, and by integrating a 
plurality of such panels while arranging the panels side by side through a 
plurality of air layers, and connecting the panels along at least part of 
the peripheries of the panels or/and at part of the surfaces of the panels 
using a connecting member. 
Note that the words "join and joint" and "connect and connecting" are not 
used to particularly mean different things. Further, the joint member and 
the connecting member may include any member that is made independently of 
the plate or integrally with the plate (by bending ends of the plate). 
Still further, in the aforementioned multi-layered panel structure, it is 
desirable to cause the joint member to joint the plates along part or all 
of the peripheries extending along the sides of the plates and cause the 
connecting member to connect the panels along part or all of the 
peripheries extending along the sides of the panels. However, the joining 
and connecting methods are not limited to this example. 
In the aforementioned multi-layered panel structure, when it is defined 
that the X axis extends in the direction of a side of a plate constituting 
the panel; the Y axis extends in parallel with the surface of the plate 
and in the direction right angles to the X axis; the Z axis extends 
perpendicular to the surface of the plate; translational springs in the X, 
Y, and Z directions are Kx, Ky and Kz; and rotary springs in the same 
directions are K.theta.x, K.theta.y and K.theta.z as shown in FIG. 2, it 
is desirable to set the rotary spring constant K.theta.x of the joint 
member whose rotary axis is the X axis to a value smaller than the 
translational springs (Kx, Ky, Kz) and the rotary springs (K.theta.y, 
K.theta.z) in all the other directions, or/and when it is defined that the 
X axis extends in the direction of a side of a panel; the Y axis extends 
in parallel with the surface of the panel and in the direction right 
angels to the X axis; the Z axis extends perpendicular to the surface of 
the panel; translational springs in the X, Y, and Z directions are Kx, Ky 
and Kz; and rotary springs in the same directions are K.theta.x, K.theta.y 
and K.theta.z as shown in FIG. 2, it is desirable to set the rotary spring 
constant K.theta.x of the connecting member whose rotary axis is the X 
axis to a value smaller than the translational springs (Kx, Ky, Kz) and 
the rotary springs (K.theta.y, K.theta.z) in all the other directions. 
Further, in the aforementioned multi-layered panel structure, it is 
desirable to set the rotary spring constant of the connecting member whose 
rotary axis extends in the direction of the side of the panel to a value 
smaller than the rotary spring constant of the joint member whose axis 
extends in the same direction, or to set the rotary spring constant of the 
joint member whose rotary axis extends in the direction of the side of the 
plate to a value smaller than the rotary spring constant of the connecting 
member whose rotary axis extends in the same direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Embodiments of the present invention will now be described with reference 
to FIGS. 1A to 17. When a plurality of plates are arranged at an interval 
in the direction of their thickness, or more specifically, when two 
1-mm-thick steel plates, each exhibiting a sound insulation performance of 
about 20 dB at 500 Hz, are arranged a sufficiently large distance apart 
from each other, a sound insulation performance of about 40 dB is 
obtained. Thus, when a plurality of plates are arranged a sufficiently 
large distance apart from each other, the sound insulation performance 
that equals the value obtained by multiplying the sound insulation 
performance of a single plate with the number of such plates is obtained, 
and this is a well known fact. On the other hand, the present invention 
has been successful in providing a thin panel structural body with a high 
sound insulation performance through such a basic construction as "a 
multi-layered panel structure in which a plurality of panels, each 
obtained by joining a plurality of plates along at least part of the 
peripheries of the plates or/and at part of their surfaces using a joint 
member, are arranged side by side through air layers, and the plurality of 
such panels are integrated by connecting such panels along at least part 
of the peripheries of the panels or/and at part of their surfaces using a 
connecting member or connecting members." 
FIG. 1A shows an example of the aforementioned multi-layered panel 
structure. A panel 3 is constructed by arranging two rectangular plates 1 
at an interval in the direction of their thickness and by joining the 
plates 1 along their peripheries using a joint member 2. Two such panels 3 
are connected using connecting members 4. Here, the joint member 2 is a 
rectangular frame-like body having a U-shaped cross section which herein 
after means a cross section just like one of the connecting member 4 of 
FIG. 1A, and joins the two plates 1 and 1 together along their entire 
peripheries to thereby form the panel 3. The connecting member 4 is 
U-shaped in cross section, and connects the two panels 3 along part of 
their peripheries, i.e., along their shorter sides. The plate 1, the joint 
member 2, and the connecting member 4 may be made of various materials 
including metals (steel, aluminum and the like) and plastics. Further, the 
methods by which the joint member 2 and the plates 1 are joined and by 
which the connecting members 4 and the panels 3 are connected may include 
any appropriate means such as adhesion, welding, bolting, pin-coupling, 
and any combination thereof. 
In the multi-layered panel structure A shown in FIG. 1A, the peripheral 
portions on the longer sides of each panel 3 are not closed by the 
connecting members 4. In place of such connecting members 4 through which 
the panels 3 are connected only along part of their peripheries, a 
frame-like integrated connecting member 4a, such as shown in FIG. 1B, 
through which the panels 3 are connected all along their peripheries, or a 
connecting member through which the panels 3 are connected all along their 
peripheries and at part of their surfaces (the part being other than the 
peripheries of the panels) (e.g., a joint member 2a, such as shown in FIG. 
1C, through which the panels are connected all along their peripheries and 
at part of their surfaces) may also be used. Further, the joint member 2 
for forming the panel 3 is a frame-like body through which the plates 1 
are joined together all along their peripheries. In place of such joint 
member 2, a joint member through which the plates 1 are joined along only 
part of their peripheries (e.g., a joint member through which the plates 1 
are joined only along their shorter side like the connecting member 4), or 
the joint member 2a, such as shown in FIG. 1C, through which the plates 1 
are joined all along their peripheries and at part of their surfaces may 
also be used. Still further, not only the joint members and the connecting 
members through which the plates 1 or the panels 3 are joined along their 
peripheries as described above, but also a joint member through which the 
plates 1 are joined only over their surfaces or a connecting member 
through which the panels 3 are connected only over their surfaces may also 
be used. 
While the aforementioned joint and connecting members have an opened (or 
U-shaped) cross section when vertically cut along their length, they may 
also have other cross sections, such as a closed (e.g., box-shaped) cross 
section. 
Note that an ordinary partition is used with its longer sides erect and its 
shorter sides opposed to the ceiling wall and the floor. In addition, a 
plurality of partitions are usually used while arranged together 
contiguously planewise with no gap. Therefore, there is no need for their 
longer sides to be closed (or it would be rather preferable to leave at 
least part of their sides opened, and this will be detailed later). The 
same applies to the formation of the panel 3, and thus the plates 1 
constituting the panel 3 may not necessarily be joined along the 
peripheral portions of their longer sides through the joint member. 
Further, if a partition is arranged contiguously, e.g., with both the 
ceiling wall and the floor with no gap, the shorter sides of the 
multi-layered panel structure (the peripheries of the shorter sides of the 
panel 3 and/or the plate 1) may not necessarily be closed, either. 
In the aforementioned multi-layered panel structure A, each panel 3 has the 
following sound insulation performance. When the distance between which 
the two plates 1 and 1 are arranged is short and the rotary spring 
constant (see FIG. 2; a rotary spring is K.theta.x with the X direction 
being the longitudinal direction of each side of the joint member) of the 
joint member 2 whose rotary axis extends in the direction of a side of the 
plate 1 (the longitudinal direction of the joint member) is large, the 
bending moment produced by the bending vibrations at the peripheral 
portion of one of the plates (the vibrations caused at such plate by 
incident sound wave) is transmitted to the other plate by the rotary 
spring of the joint member 2 through the joint member 2. Further, the air 
layer formed between the plates 1 and 1 acts as a pneumatic spring, and 
the vibrations caused at such one of the plates are transmitted to the 
other plate through the air. Since the vibrations at one plate are 
transmitted to the other through the joint member 2 and the pneumatic 
spring as described above, the sound insulation performance of the panel 3 
is expressed in terms of a value lower than that obtained by simply 
multiplying (doubling) the sound insulation performance of a single plate 
with the number of such plates. 
However, by setting the rotary spring constant of the joint member 2 whose 
rotary axis extends along its length (the X axis in FIG. 2) to a value 
lower than the translational and rotary springs in all the other 
directions (K) .theta.x&lt;K.theta.y, K.theta.z, Kx, Ky, Kz in FIG. 2), the 
amount of bending moment produced at one plate which is to be transmitted 
to the other plate can be reduced. Therefore, even if a plurality of 
plates are arranged a short distance apart from each other, the sound 
insulation performance of the panel can be made closer to the value 
obtained by multiplying the sound insulation performance of a single plate 
constituting the panel with the number of such plates. To implement this, 
it is desirable to make K.theta.x of the joint member 2 sufficiently 
smaller than K.theta.y, K.theta.z, Kx, Ky, and Kz. This could be 
implemented, e.g., by providing the joint member 2 with a relatively thin 
opened cross section (e.g., a U-shaped cross section; see FIGS. 1A to 1C), 
by making the height of the joint member 2 (the distance between the 
plates 1 and 1) large, by giving the joint member 2 a shape other than the 
integrated frame-like body, by using a joint member 2b having slits a at 
its corners as shown in FIG. 3, or by joining the plates 1 and 1 through 
the joint member 2 while interposing a vibration-isolating material such 
as rubber between each plate 1 and the joint member 2. (Note that in FIG. 
2, x denotes the longitudinal direction of the joint member 2 (the 
direction extending along a side of the plate); y the direction right 
angles to x and parallel with the surface of the plate 1; z the direction 
perpendicular to the surface of the plate 1; and K.theta.x, K.theta.y, 
K.theta.z, Kx, Ky, and Kz the rotary and translational springs in the 
respective directions). 
Further, FIG. 4A shows an example for implementing a joint member whose 
K.theta.x is zero. The plate 1 is joined to the frame-like joint member 2 
all along its periphery through hinges b, and the rotary spring constant 
of the joint member 2 is set to zero (while the translational and rotary 
springs in all the other directions have appropriate values). 
Further, even if K.theta.x is decreased, when K.theta.y, K.theta.z, Kx, Ky, 
and Kz are increased to relatively larger values, the elastic deformation 
of the integrated panel 3 which is caused by the weight of the panel 3 
when the panel 3 is suspended from above can be reduced to a considerable 
degree. In addition, the elastic deformation of the panel 3 which is 
caused by the loads to be applied when the panel 3 is manually moved after 
suspended can be reduced as well. 
Still further, instead of joining the plates 1 and 1 through the frame-like 
joint member 2 all along their peripheries as shown in FIGS. 1A to 1C, the 
plates 1 and 1 are joined through the member 2 along only part of their 
peripheries (e.g., like the connecting members 4 shown in FIG. 1A) to 
thereby prevent the air from being enclosed within the closed space. Since 
this decreases the pneumatic spring constant of the air, those vibrations 
which are out of the vibrations caused at one plate and which the 
pneumatic spring transmits to the other plate can be reduced. As a result, 
the sound insulation performance of the panel is made further closer to 
the sound insulation performance obtained by multiplying the sound 
insulation performance of a single plate constituting the panel with the 
number of such plates. 
The aforementioned relation between the plates 1, 1 and the joint member 2 
applies in exactly the same way to that between the panels 3, 3 and the 
connecting member 4. That is, in the aforementioned multi-layered panel 
structure A, each panel 3 has the following sound insulation performance. 
When the distance between which the two panels 3 and 3 are arranged is 
short and the rotary spring constant (see FIG. 2; a rotary spring is 
K.theta.x with the X direction being the longitudinal direction of each 
side of the connecting member) of the connecting member 2 whose rotary 
axis extends in the direction of a side of the panel 3 (the longitudinal 
direction of the connecting member) is large, the bending moment produced 
by the bending vibrations at the peripheral portion of one of the panels 
(more correctly, one plate on the side of the connecting member out of the 
plates constituting such one of the panels) is transmitted to the other 
panel (more correctly, one plate on the side of the connecting member out 
of the plates constituting such other panel) by the rotary spring of the 
connecting member 4 through the connecting member 4. Since the vibrations 
at one panel are transmitted to the other through the connecting member 4 
as described above, the sound insulation performance of the multi-layered 
panel structure is expressed in terms of a value lower than that obtained 
by simply multiplying (doubling) the sound insulation performance of a 
panel with the number of such panels. 
However, by setting the rotary spring constant of the connecting member 4 
whose rotary axis extends along its length (the X axis in FIG. 2) to a 
value lower than the translational and rotary springs in all the other 
directions (K.theta.x&lt;K.theta.y, K.theta.z, Kx, Ky, Kz in FIG. 2), the 
amount of bending moment produced at one panel which is to be transmitted 
to the other panel can be reduced. Therefore, even if a plurality of 
panels are arranged a short distance apart from each other, the sound 
insulation performance of the multi-layered panel structure can be made 
closer to the value obtained by multiplying the sound insulation 
performance of each panel with the number of such panels. To implement 
this, it is desirable to make K.theta.x of the connecting member 
sufficiently smaller than K.theta.y, K.theta.z, Kx, Ky, and Kz. 
Conceivable specific means for implementing this may include, e.g., such 
shapes and connecting methods as described above with respect to the joint 
member. 
Similarly, FIG. 4B shows an example for implementing a connecting member 
whose K.theta.x is zero. The panel 3 is connected to the frame-like 
connecting member 4 all along its periphery through the hinges b, and the 
rotary spring constant of the connecting member 4 is set to zero (while 
the translational and rotary springs in all the other directions have 
appropriate values). 
Further, even if K.theta.x is decreased, when K.theta.y, K.theta.z, Kx, Ky, 
and Kz are increased to relatively larger values, the elastic deformation 
of the integrated multi-layered panel structure which is caused by the 
weight of the structure when the structure is suspended from above can be 
reduced to a considerable degree. In addition, the elastic deformation of 
the multi-layered panel structure which is caused by the loads to be 
applied when the structure is manually moved after suspended can be 
reduced as well. 
Still further, for uniting the panels 3 and 3 through the connecting member 
4, the panels 3 and 3 are connected through the connecting members 4 along 
only part of their peripheries as shown in FIG. 1A (along only their 
shorter sides in FIG. 1A) to thereby prevent the air from being enclosed 
within the closed space. Since this decreases the pneumatic spring 
constant of the air, those vibrations which are out of the vibrations 
caused at one panel (more correctly, the plate on the side of the 
connecting member out of the plates constituting such one panel) and which 
the pneumatic spring transmits to the other panel (more correctly, the 
plate on the side of the connecting member out of the plates constituting 
such other panel) can be reduced. As a result, the sound insulation 
performance of the multi-layered panel structure is made further closer to 
the sound insulation performance obtained by multiplying the sound 
insulation performance of a single panel with the number of such panels. 
Thus, when the spring constants in the respective directions shown in FIG. 
2 are set so as to satisfy K.theta.x&lt;K.theta.y, K.theta.z, Kx, Ky, Kz 
(more preferably K .theta.x&lt;&lt;K.theta.y, K.theta.z, Kx, Ky, Kz) in either 
one or both of the joint member 2 and the connecting member 4. In the 
former case, the sound insulation performance of the panel can be made 
closer to the sound insulation performance obtained by multiplying the 
sound insulation performance of a single plate constituting the panel with 
the number of such plates, and in the latter case, the sound insulation 
performance of the multi-layered panel structure can be made closer to the 
sound insulation performance obtained by multiplying the sound insulation 
performance of a single panel with the number of such panels. 
It is further desirable to set the rotary spring constant K.theta.x of the 
connecting member 4 whose rotary axis extends in the direction of the side 
of the panel 3 to a value smaller than the rotary spring constant 
K.theta.x of the joint member 2 whose rotary axis extends in the same 
direction, or to set the rotary spring constant K.theta.x of the joint 
member 2 whose rotary axis extends in the direction of the side of the 
plate 1 to a value smaller than the rotary spring constant K.theta.x of 
the connecting member 4 whose rotary axis extends in the same direction. 
Such settings aim to reduce the amount of transmission of the bending 
moment produced at one plate (or panel) to the other plate (or panel) by 
making the rotary spring constant K.theta.x of either the joint member 2 
or the connecting member 4 smaller than that of the other member. 
Next, other examples of multi-layered panel structures according to the 
present invention will be described with reference to FIGS. 5 to 16. 
In a multi-layered panel structure of the present invention, one or more of 
a plurality of panels constituting the multi-layered panel structure may 
be made up of a plurality of panel segments. In this case, it is desirable 
to use a frame-like connecting member and to connect the panel segments to 
both surfaces of the connecting member along their peripheral portions. 
FIG. 5 shows such an example, which is a multi-layered panel structure B 
comprising two panels 3a, each being made up of a plurality of panel 
segments 3-1 to 3-4. Each of the panel segments 3-1 to 3-4 used in this 
multi-layered panel structure B is, similarly to the so far described 
panel 3, formed by arranging two plates at an interval in the direction of 
their thickness and joining these plates along their peripheries using a 
joint member. Two sets of such panel segments 3-1 to 3-4 forming two 
panels 3a, respectively, are connected to both surfaces of the frame-like 
connecting member 4, thereby providing a large area. 
To join the panel segments 3-1 to 3-4 together firmly for forming the 
multi-layered panel structure B, the plates forming one of any two 
adjacent panel segments may, if necessary, be projected outward to thereby 
form a recess and the joint member of the other adjacent panel segment is 
projected outward from its plates to thereby form a projection, so that 
the projection is fitted into the recess, and it is preferable that with 
the projection fitted into the recess that way in every two adjacent panel 
segments, the panel segments are joined to the connecting member or their 
adjacent joint members are joined to each other. FIGS. 6A and 6B show such 
an example. A recess d is formed by projecting the plates 1 outward in the 
panel segment 3-1, while a projection e is formed by projecting the joint 
member 2 outward from the plates 1 in the panel segment 3-2. The 
projection e is designed to be fitted into the recess d. 
In a multi-layered panel structure of the present invention, a large-area 
multi-layered panel structure can be formed by arranging a plurality of 
small-area multi-layered panel structures contiguously planewise and by 
joining the adjacent joint members or/and connecting members together. 
FIG. 7 shows such an example, which is a multi-layered panel structure C 
having a large area. In the structure C, a plurality of multi-layered 
panel structural bodies C1 to C4 are arranged contiguously planewise and 
their adjacent joint members or/and connecting members are joined 
together. Here, each of the multi-layered panel structural bodies C1 to C4 
is constructed of two panels 3 and connecting members 4 for connecting 
these panels 3 in a manner similar to the multi-layered panel structure 
shown in FIG. 1A. 
In order to join the multi-layered panel structural bodies C1 to C4 
together firmly for forming the multi-layered panel structure C, the 
plates forming each panel of one of any two adjacent panel structural 
bodies may, if necessary, be projected outward from their joint member to 
thereby form a recess and the joint member of each panel of the other 
adjacent panel structural body is projected outward from its plates to 
thereby form a projection, so that the projection is fitted into the 
recess, and it is preferable that with the projection fitted into the 
recess that way in every two adjacent panel structural bodies, the 
adjacent joint members or/and connecting members are joined to each other. 
FIGS. 8A and 8B show such an example. Recesses d and f are formed by 
projecting the plates 1 outward in each panel 3 of the multi-layered panel 
structural body C1, while projections e and g are formed by projecting the 
joint member 2 and the connecting member 4a outward from the plates 1 in 
each panel of the multi-layered panel structural body C2. The projections 
are designed to be fitted into the corresponding recesses. 
Further, the panels of any two adjacent panel structural bodies may be 
projected outward from their connecting member to thereby form a recess, 
and the connecting member of the other adjacent panel structural body may 
be projected outward from its panels to thereby form a projection. 
In a multi-layered panel structure of the present invention, members for 
suspending the multi-layered panel structure from above may be attached to 
the joint member or/and the connecting member. FIG. 9 shows such an 
example, which is a multi-layered panel structure in which members 
(projections h in this example) for suspending the multi-layered panel 
structure from above are attached to one of the connecting members 4. 
Further, when the multi-layered panel structure according to the present 
invention is suspended from above, a seal device may be attached to the 
joint member and/or the connecting member for closing the clearances 
formed with respect to the existing structures which extend above and 
below the multi-layered panel structure (e.g., the ceiling wall and the 
floor), or the joint member and/or the connecting member may double as 
such a seal device. 
Still further, when the multi-layered panel structure according to the 
present invention is used so as to be arranged contiguously planewise, a 
seal device for closing the clearances formed between the horizontally 
adjacent multi-layered panel structures may be attached to the joint 
member and/or the connecting member, or the joint member and/or the 
connecting member may double as such a seal device. 
In a multi-layered panel structure of the present invention, a 
sound-absorbing material may be provided in at least one of the plurality 
of air layers (between the plates 1 and 1) to thereby improve its sound 
insulation performance. FIG. 10 shows such an example, which is a 
multi-layered panel structure D, in which a sound-absorbing material i is 
provided in the air layer between the panels 3 and 3 out of the plurality 
of air layers constituting the multi-layered panel structure. The 
sound-absorbing material i may also be arranged in the air layer within 
the panel 3. The sound-absorbing material i may include, e.g., those made 
of viscoelastic bodies having an open cell such as urethane foams and 
fibrous sound-absorbing materials such as glass wool. Using any of these 
materials, part of the energy of sound wave transmitted from one plate to 
the other via the air layer can be attenuated, thereby improving the sound 
insulation performance. 
Further, when any such sound-absorbing material is brought into contact 
with one or both surfaces of the plates interposing the air layer 
therebetween (e.g., when the sound-absorbing material is squeezed into the 
space between the plates), vibrations of the plates can be suppressed, 
thereby allowing coincidence phenomena to be suppressed. 
In a multi-layered panel structure of the present invention, a restraining 
type damping plate (the plate obtained by sandwiching a viscoelastic body 
between two plates) may be used for at least one of a plurality of plates 
constituting such multi-layered panel structure, or a viscoelastic body is 
stuck onto one surface of at least one of the plurality of plates, thereby 
allowing its damping action to damp the vibrations of the plates and 
improve the sound-insulating effect. FIG. 11 shows such an example, which 
is a multi-layered panel structure E, in which restraining type damping 
plates 1a are used as the outer plates of its panels 3 and 3. 
In a multi-layered panel structure of the present invention, the plates 
constituting such multi-layered panel structure and their joint member, 
and/or the panels and their connecting member are united together through 
a vibration-isolating material. As a result of this construction, the 
rotary spring constant of the joint member (the rotary spring constant of 
the joint member whose rotary axis extends in the direction of a side of 
the plate) and/or the rotary spring constant of the connecting member (the 
rotary spring of the connecting member whose rotary axis extends along a 
side of the panel) can be reduced. 
FIG. 12 shows a panel 3b in which the joint member 2 that is U-shaped in 
cross section is used and two plates 1 and 1 are respectively joined with 
fixing pins k through elastic bodies j that are made of rubber or the 
like. In this structure, the rotary spring constant K.theta. of the joint 
member 2 whose rotary axis extends in the direction of a side of the plate 
1 (along the length of the joint member 2 in FIG. 12, or in the direction 
perpendicular to the sheet) decreases. FIG. 13 shows a multi-layered panel 
structure F in which the connecting member 4 that is U-shaped in cross 
section is used and two panels 3 and 3 are joined respectively with fixing 
pins m through the elastic bodies j. In this structure, the rotary spring 
constant K.theta. of the connecting member 4 whose rotary axis extends in 
the direction of a side of the panel 3 (along the length of the connecting 
member 4 in FIG. 13, or in the direction perpendicular to the sheet) 
decreases. FIG. 14 shows a multi-layered panel structure G in which a 
connecting member 4b that is closed (box-shaped) in cross section is used 
and two panels 3 and 3 are joined respectively with a fixing pin n through 
the elastic bodies j. In this structure, the rotary spring constant 
K.theta. of the connecting member 4b whose rotary axis extends in the 
direction of a side of the panel 3 (along the length of the connecting 
member 4b in FIG. 14, or in the direction perpendicular to the sheet) 
decreases. Owing to the use of the vibration-isolating material as in the 
multi-layered panel structure G, the connecting member (or the joint 
member, likewise), which has a closed cross section and thus would have an 
extremely large rotary spring constant with its axis extending in the 
longitudinal direction if the member were not provided with such a 
vibration-isolating material, can have the same rotary spring constant 
reduced to a smaller value. 
In a multi-layered panel structure of the present invention, any two 
adjacent ones of a plurality of plates constituting the multi-layered 
panel structure are set to different thickness to thereby suppress 
coincidence phenomena. FIG. 15 shows such an example, which is a panel 3c 
in which a thick plate 1b and a thin plate 1c are joined using the joint 
member 2. 
In a multi-layered panel structure of the present invention, the joint 
member or/and the connecting member for constituting the multi-layered 
panel structure are made of a restraining type damping plate, or a 
viscoelastic body is stuck to the joint member or/and the connecting 
member to thereby decrease the vibration transmission coefficient between 
adjacent plates owing to its damping action. FIG. 16 shows such an 
example, which is a panel 3d, in which the plates 1 and 1 are joined using 
the joint member 2 and a viscoelastic body p is stuck to the joint member 
2. 
EXAMPLES 
Examples of the present invention will hereunder be presented. 
Each of multi-layered panel structures (Examples 1 and 2) used here is a 
150-mm-thick, 1-m-wide, 3-m-high rectangular parallelopiped (in terms of 
appearance) formed by connecting panels to both surfaces of a frame-like 
connecting member. Glass wool is used to fill in the air layer within the 
connecting member. Details of their components are shown in Table 1. 
For each of the multi-layered panel structures which are Examples 1 and 2, 
four panels are joined contiguously planewise with no gap to thereby form 
a 4-m-wide and 3-m-high partition. The sound transmission losses of each 
multi-layered panel structure with respect to one third octave band 
central frequency were measured based on the method specified in JIS 
(Japanese Industrial standard) A 1417. The results are shown in FIG. 17. 
Note that FIG. 17 also shows the lines indicating reference frequency 
characteristics for grades D35 to D50. 
As shown in FIG. 17, the multi-layered panel structure, whose thickness is 
150 mm and whose weight per unit area is 32.3 kg/m (Example 1), passed 
D50. Further, the multi-layered panel structure, whose thickness is 100 mm 
and whose weight per unit area is 20.0 kg/m (Example 2), passed D40. 
TABLE 1 
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Example 1 
Total size 150 mm (thickness ) .times. 1 m (width) .times. 3 m (height) 
Weight 32.3 kg/m.sup.2 
Plates 
Outside of 
Restraining type damping plate formed by clamping 
the panel a 100-.mu.m-thick viscoelastic body between two 
2-mm-thick aluminum plates 
Inside of the 
1-mm-thick aluminum plate 
panel 
Joint member 
Made of 1-mm-thick aluminum plate, frame-like, 
box-shaped cross section (outside dimensions: 
10 mm .times. 10 mm) 
Connecting Made of 1-mm-thick aluminum plate, frame-like, 
member U-shaped cross section (Height of the web portion: 
120 mm) 
Sound-absorbing 
32 kg/m.sup.2 
material 
Example 2 
Total size 100 mm (thickness) .times. 1 m (width) .times. 3 m (height) 
Weight 20.0 kg/m.sup.2 
Plates 
Outside of 
2-mm-thick aluminum plate 
the panel 
Inside of the 
1-mm-thick aluminum plate 
panel 
Joint member 
Made of 1-mm-thick aluminum plate, frame-like, 
box-shaped cross section (outside dimensions: 
10 mm .times. 10 mm) 
Connecting Made of 1-mm-thick aluminum plate, frame-like, 
member U-shaped cross section (Height of the web portion: 
74 mm) 
Sound-absorbing 
32 kg/m.sup.3 
material 
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