Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
FIELD OF THE INVENTTON
The invention relates to a sound insulating door designed, for
example, to close test chambers for nGisy apparatus such as jet
engines.
THE PRIOR ART
In many fields of construction and industry, it is frequently
necessary to soundproof noisy equipment and, notably, to surround a
particularly noisy sound source with a soundproof enclosure. The
processes for producing such enclosures are well known; nonetheless,
difficulties are encountered with regard to the openings and, in
particular, th0 doors.
It proves difficult to produce this type of door as a compromise
has to be found between the weight that can be mechanically
supported and the noise damping factor. That is why it is a vital
element in the construction of a soundproofed enclosure and it is
particularly important to take pains in manufacturing the door.
It is known that the use of a high density, and thus heavy,
material favours the damping of low frequency noises. However,
20 extensive use of this type of high density material makes the door
very heavy and makes it necessary to reinforce it. This is a
critical point as the reinforcements are generally produced using
metallic sections which, in their turn, create noise backgrounds
that are extremely prejudicial to the noise damping factor. The
25 havy doors are also more difficult to manoe w er and necessitate the
use of special locking and articulation systems which are
particularly conplex.
To cover a relatively broad frequency spectrum, the doors use
different types of insulating material, each having a frequency
range in which they are more active. To permit their installation,
the doors are divided into compartments using rigid intermediate
partitions that act as separators. These partitions serve to
maintain the insulating materials, which are generally very
flexible.
Another delicate point also encountered in the development of
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sound insulating doors concerns the tightness of the door. Indeed,
the joints must not form pre~erential passages for noises, although,
generally, from the construction viewpoint, an interval is left
between the door and its frame. At the present time, the man of the
s art makes use of peripheral seals that are subjected to considerable
compression to ensure tightness. These seals tend to lose their
elasticity and thus no longer perform their function.
SUMMARY OF THE INVENTION
The main object of the present invention is to provide a sound
10 insulating door which combines lightness and efficiency. With regard
to performance, the example given in the following description
permits damping in the order of 50 dB, while, with a more
sophisticated design, this can be increased to 60 dB. It should be
stressed that these characteristics are obtained with a door weight
15 that is well below the mean, in the order of 1 ton.
The door is efficient over a very extensive frequency spectrum,
despite its small overall thickness.
Another object of the present invention is to provide a sound
insulating door which also has ant;-fire properties. Also in
20 connection with safety, the sound insulating door according to the
present invention is equipped with a quick-opening device actuated
by an 'anti-panic' button.
Further objects and advantages of the present invention will
emerge in the course of the following description which is provided,
25 however, solely by way of information.
According to the invention, the sound insulating door designed,
in particular9 to close test chambers for noisy equipment such as
jet engines, which comprises a frame fixed in the walls of the
chamber, articulating hinges and a locking mechanism, is
30 characterized by the fact it has the following structure:
- a rigid outer metal plate,
- a soundproofing material,
- one or more elastically mounted central metal plates,
- a soundproofing material,
- a rigid outer metal plate.
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The invention will be more readily understood as a result of
reading the following description accompanied by the annexed
drawings.
THE DRAWIN~S
- figure 1 is a front view of the sound insulating door
according to the invention,
- figure 2 is a cross-sectional view of the internal structure
of the door,
- figure 3 is a cross-sectional view of a sound insulating door
10 with enhanced properties,
- figure 4 illustrates the locking mechanism.
DESC~IPTION OF THE PREFERRED EMBODIMENT
The present invention relates to a sound insulating door
designed, for example, to close test chambers andJor soundproofed
15 enclosures around noisy apparatus.
To permit the operation, or the inspection or testing, of
certain items of equipment that are extremely noisy when in
operation, it is necessary to make use of entirely soundproofed
rooms in order to avoid inconvenience to the environment and the
20 technical personnel. Use is generally made of buildings with solid
walls having coatings of absorbent material. The soundproofed
enclosures naturally have access doors, which must also be of a
sound insulating typa in order to conform to the general
soundproofing measures adopted. In this connection, certain
25 technical design difficulties are encountered as, in order to
achieve the desired insulation objectives, it is necessary to use an
extremely heavy door. The sound frequencies of the noise to be
attenuated are extremely wide and varied; now, the absorption
characteristics of the insulating materials are a function of
30 frequency, whence the use of several types of insulating material in
order to cover a broad spectrum of frequencies to be damped.
At the present time, constructors manufacture doors provided
with several compartments separated by rigid partitions and in which
are placed the different insulating materials chosen. As a result of
35 this arrangement, there occurs a sort of interference in the form of
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sound bridges between the contiguous insulating materials, which
substantially lowers their individual performance.
Furthermore, certain soundproofing shortcomings are noted at the
periphery of the door owing to the existence of a slight space
between it and the frame. Present tightness-ensuring techniques
using compressed peripheral seals have very limited useful lives
owing to the crushing of the seal, which very quickly loses its
properties.
The sound insulating door accordin~ to the present invention
provides a solution to these problems thanks to an improvement in
properties, also associated with a reduction in weight.
Figure 1 is a front view of the sound insulating door 1 according
to the present invention. This door 1 comprises a frame 2 designed
to be fixed to the walls of the test chamber that they surround.
Sound insulating door 1 also comprises articulating hinges 3
which interconnect frame 2 and the leaf, 4, of door 1. In the
examp1e chosen, two hinges suffice, given the moderate weight of the
des~gn in question.
Sound ~nsulating door 1 a7so comprises a locking mechanism
operated by a handle 6.
The details of the internal architecture of door 1 are
illustrated in figure 2, which is a cross-section of a preferred
form of embodiment of the i m ention. Frame 2 is firstly formed by a
bearing section 7 designed to be fixed to the enclosure. This
U-shaped section 7 is extremely rigid and enables the door to be
fixed to the enclosure. Frame 2 also comprises a supporting
peripheral metal plate 8 maintained by two angle irons 9 and 10 on
section 7. It is to this plate 8 that hinges 3 are fixed, and the
plate will also serve as a supporting plane for the seals to oe
described subsequently. Door frame 2 is also composed of a frame 11
formed by an assembly of tubular sections with a square
cross-section in the example chosen. This frame 11 will also serve
to support the second seal, to be described below.
As regards leaf 4 of door 1, this has the following structure: a
rigid outer metal plate 12, a soundproofing material 13, an
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elastically mounted central metal plate 14, a soundproofing material
15 and~ finally, a rigid outer metal plate 16, such as the one
illustrated in figure 2.
In this way, door 1 is divided into compartments owing to the
presence of central37et81 plate 1~, which permits the definition of
the two compartments ~n which insulating materials 13 and 15 are
placed respectively. The flexible mounting of central metal plate 14
makes it possible to preserve the integrity of the insulating
properties of each of materials 13 and 15. This is a valuable asset
as, unlike prior designs wherein the central metal plate serving to
divide the door into compartments was mounted rigidly and there was
prejudicial interference between the damping elements, flexible
mounting makes it possible to accumulate the soundproofing
properties. This makes it possible to cover a broad range of `
attenuated frequencies with a relatively small thickness of
insulating material. Practically speaking, use can be made, for
example, of a diaphragm to support central metal plate 14 or, more
simply, the waddings 13 and 15 of insulating material can themselves
be used to ensure that central metal plate 14 is actually held in
place.
The value of this technique ~ill be all the more appreciable in
that the insulating materials used for compartments 37 and 38 will
have different density characteristics. ~or example, use can be made
of a glass wool based insulating material the density of which is
70 k/m3 to fill compartment 37, and a glass wool with a density of
100 k/m3 to fill compartment 38 .
- Similarly, the respective volumes of compartments37 and 38 can
be different and, ~n the example chosen, the low density insulating
material 13 occupies a volume that is twice that of the high density
insulating material 15.
The edges of central metal plate 14 can, for example~ be
slightly separated from the periphery of the door to prevent any
contact, or simply pressed against this periphery without any rigid
system of fixing.
The surround of leaf 4 of door 1 is formed by a sheet metal
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section 17 the inside of which is filled with insulating material
18. Tne edges of the door are fo~med by a perforated metal plate 19
the positioning of which in relation to section 17 is adjustable.
This makes it possible to reduce the distance between leaf 4 and
frame 2. Thus sound leakage is reduced and, thanks to the holes in
perforated metal plate 19, it is also possible to absorb the sounds
that transit via the existing interval.
It should be noted that outer edge 20 of door 1, i.e. opposite
hinges 3, will preferably be inclined as represented in figure 2.
This bevelled external shape makes it possible to enhance the sound
insulation by reducing the interval between edge 20 and metal plate
8, at the same time allowing for the relatively great thickness of
the door.
Test have shown that large noise leakages were encountered as a
consequence of a lack of tightness between leaf 4 and frame 2. For
this purpose, the invention recommends the use of peripheral seals,
for example of closed-cell neoprene, the first of which, 21, is
placed between rigid outer metal plate 16 and frame section 8, as
illustrated in figure 2. The second seal, 22, is placed between the
second rigid outer metal plate 12 and frame section 11.
The sound insulating door as described perm1ts up to
approximately 51 dB attenuation of noises over a broad frequency
band for a door weight of 250 kg to 1 ton, according to dimensions.
Under certain circumstances, it is necessary to achieve up to
60 dB noise reduction. To achieve such a performance, it is
necessary to undertake certain modifications to the inner structure
of the door, as in figure 3. In this case, leaf 4 of door 1 has the
following structure: a rigid outer metal plate 12 identical with the
previous one; the same applies to the first compartment 37 filled
with insulating material; however, this time, two central metal
plates 23 and 24 are interposed, separated by a belt of air 25. The
rest of the door remains the same as before, that is to say a second
compartment 38 containing insulating material and a rigid outer
metal plate 16. Advantageously, all the faces of the walls located
lnside leaf 4 of door 1 will be covered by a layer of high density
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bitumen which very substantially enhances noise attenuation~ Central
metal plates 23 and 24 are separated by spacing pieces 27. These
central metal plates 23 and 24 are not fixed and are freely mounted
inside door 1. It would, of course, be possible to conceive of using
several compartments separated by different central metal plates at
least some of which are freely mounted.
As to the closing mechanism, this comprises an operating laver 6
articulated about a control pin 28, as represented in figure 3. The
rotation of control lever 6 can be obtained directly or via an
'anti-panic' pushbutton 29, the pin of which passes through the door
and presses against lever 6.
Figure 4 illustrates locking mechanism 5 properly speaking.
Control pin 28 pivots in a journal 29 fixed to outer metal plate 16
~ lever 30 fixed to control pin 28 is connected to a chain 31 the
end of which is connected to the pin of latch 32. This latch slides
freely in a support 33 and is held in extended position via a spring
34. The travel of latch 32 in extended position is limited by a nut
35.
When control pin 28 is operated using lever arm 6, lever 30 is
rotated and drives chain 31, pulling on latch 32 to release the
locking system. Apart from the action on lever 6, spring 34 ensures
the return of latch 32 to locking position. The whole is enclosed by
a housing 36.
In the chosen example in figure 1, door 1 is provided with a
double locking system 5, which enables it to withstand external
pressures in the order of 750 kg/m2. Given the stresses encountered
and the weight of the door, it is necessary to make use of a special
locking system.
Further embodiments of the present invention within the reach of
a man of the art could also be contemplated without thereby
departing from the scope thereof.
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