FR2650332A1 - GLAZING OF THERMAL AND ACOUSTIC PROTECTION - Google Patents

Abstract

Thermal and acoustic insulating glazing is available. It consists of two sheets of glass, the thickness of which differs only by 20 to 26%. The glazing can also include a heavy gas in its atmosphere. The improvement concerns both the attenuation index weighted according to ISO and the sound reduction index for road noise, both for the glazing alone and for the window where it is installed.

Description

GLAZING OF THERMAL AND ACOUSTIC PROTECTION

  The invention relates to thermal insulating glazing

  improved acoustic properties.

  For many years, in many countries,

  the use of thermal insulating glazing

  ralisée. Most often, they consist of two glasses of the same thickness, generally between 2.5 and 4 millimeters, separated by a blade of dry air 6 to 12 millimeters and glued to their periphery with various mastics and possibly metal profiles. During the heating period, such glazings improve the comfort of living, working or leisure

  significantly decrease heat losses.

  But in some noisy areas, it is also desirable to

  also benefit from reinforced sound insulation.

  This is why various techniques have been proposed for

  improve the sound insulation performance of

  thermally insulating trims or windows in which

they are intended to be laid.

  Among these techniques, many call upon the

  pleating the space between the glasses with a heavy gas, with a molecular weight greater than 100 such that the

  chlorofluorocarbon or sulfur hexafluoride in particular

  ticular. In addition to the fact that these gases may pose a risk

  for the environment since they are chemically particulate

  are stable and are only separated by

  ultraviolet elements of the upper atmosphere where

  Their decomposition destroys the protective ozone layer, all of them have the disadvantage of

  acoustics a challenged efficiency. Indeed, if they

  the effect of lowering the attenuation at low frequencies, where the insulation due to the mass of glass is the lowest and also where the spectrum Road noise is the most intense.

  Other methods proposed to improve

  acoustical forms of thermal insulating glazings, ie multiple glazings and in particular

  double glazing, for reasons of acoustic

  than theoretical, which will be discussed later, to associate unit glasses of different thicknesses, possibly

  in the form of laminated glazing. In some cases

  laughing, the interlayer film of the laminated glazing has

  improved acoustic performance. These last solutions

  which undoubtedly improve in a more or less

  acoustic performance has the greatest

  come to be expensive (in the case of laminates), heavy and significantly increase the thickness of glazing and therefore require the use of special windows mechanically reinforced.

  The invention, on the other hand, proposes an acoustic solution

  effective, simple, inexpensive and

  use the usual rebate depth.

  The glazing according to the invention, intended to provide thermal and acoustic protection, consists of two glass sheets of different thicknesses separated by a blade of air or another gas, it is characterized in that the difference between thicknesses reported at most glass

thin is less than 26%.

  In a preferred variant this difference falls below 22%. According to the invention, it is also expected that the same

  difference remains greater than 20%.

  In a variant of the invention, the thickness of the glass

  the thinnest remains less than 4 mm.

  It is also envisaged, within the scope of the invention, to introduce into the space between the glasses a heavy gas of molecular mass greater than 100. This gas may advantageously be sulfur hexafluoride in a

proportion of at least 30%.

  The glazings according to the invention have the unexpected advantage that a good acoustic insulation is obtained for a very small thickness difference between the two.

  glasses constituting the insulating glazing. The glazings cor-

  respondent are therefore thinner and lighter than the

traditional acoustic glazing.

  The following figures and description will allow

  to understand the operation of the invention and its advantages. FIG. 1 represents the acoustic loss index of a traditional insulating glazing unit comprising two 4 mm glasses separated by an air gap of 12 mm, FIG. 2 represents the same index in the low frequency range for a glazing unit according to the invention and for

  glazing at the edge of the field of the invention. The

  Figures 3 and 4 show for glazing composed by the combination of a glass of 3.9 mm with glasses of varying thicknesses, the overall acoustic results for glazings measured either alone or in a window

  in aluminum, again, in. a good PVC window.

  Figure 3 shows the attenuation index in dB (A)

  for a normalized road noise and Figure 4, the

in dB of the ISO standard.

  If we observe the curve 1 representing the sound reduction index of a double glazing in

  Frequency function (Figure 1), an isolation is observed

  which increases with frequency. The general position of

  the curve, its "height" in the direction of the axis of the

  data is only determined by the mass per unit area of each wall and the distance between them: the thicker the glasses, the higher the attenuation. The variation of the attenuation as a function of frequency is a growth with a theoretical slope of 18 dB per octave. It is only at both ends of the spectrum that this general rule no longer applies. In the first of these areas, in the high frequencies, minima 2 are

  produce for so-called critical frequencies

  c. Similarly, in bass, for a frequency fr said resonance frequency, there is a minimum 3. In these

  two areas of the frequency spectrum, acoustic isolation

  The cost of the wall is reduced compared to what it is in neighboring areas. The means to modify

  the weakening of the wall in these areas are

  particularly sought after by the acousticians. this is

  especially true for the "hole" 3 at the resonant frequency

  because in this zone the weakening is - inde-

  the "hole" - the lowest of the entire acoustic spectrum. It is also at low frequencies that

  road noises are the most intense.

  In the field of acute, the problems are less arduous (higher attenuation and less intense noise source) but, in addition, relatively simple means have been found that improve the attenuation produced by double glazing in this area: we have

  discovered that by partially replacing dry air with

  inside the insulating glazing by a gas where the speed of sound is different from what it is in the air, in particular by a heavy gas which has the advantage over gases lighter than air, of diffusing very slowly through the joints of the insulating glazing over time, the slope of the weakening curve in the mid and high frequencies was increased which improved the acoustic insulation in these areas.

  frequency domains. This made it possible to achieve better

  their performance for special glazing in

  in particular according to DIN or ISO standards, where the notion of

  Weighted loss dice can be reported using a single value, R, isolation performance

of the wall.

  Thus in an insulating glass consisting of two 4 mm glasses associated with a space of 12 mm, the introduction of SF6 at a concentration of 80% in the air makes R.

  a value of 30.2 dB at a value of 32.9 dB.

  However, the two techniques, the use of special gases or the modification of the overall constant thicknesses, which are often used simultaneously, have little effect (or sometimes a detrimental effect) on the "hole" 3 of the bass. frequencies. In this area, where the phenomena

  resemble the behavior of a mass association -

  spring-mass, only two techniques are effective, the action by the law of mass: one "raises" the whole of the curve by increasing the surface mass of the wall or the modification of the characteristic of the "spring" which requires a change in the thickness of the spacer air blade. Unfortunately the effects are measurable

  here only if this thickness reaches several centimeters ...

  It is in this area of low frequencies that the invention

brings a surprising solution.

  By measuring sound attenuation indices for combinations of glasses of different thicknesses associated with identical air or gas blades, an inexplicable improvement

  the difference in thickness reaches 20%. -.

  In Table I, we find for low frequencies

  quences, measured sound reduction indices R

  according to ISO 140 parts 1 and 3, for combinations of

  sounds in which a 3.9 mm soda-lime-silica glass is associated via a 12-mm dry air-gap to another glass of thickness d, d varying by one tenth

mm from 3.9 to 4.8 mm.

TABLE I

I IS

  mm 3.9 I 4.1 4.2 4.3 4.4 1 4.54.6 4.7 4.8 I I j. I I I I I I I I I I I I H

I I I 1. 1 1 I 1

  19.4 19.4 19.4 18.7 19.7 1 20.1 19.6 1 20.51 19.9

  125 19.8 19.6 19.5 19.7 1 21.1 4 22.4 22.1 d 22.21 21.2

  22.2 22.6 21.6 22.1 22.3 1 21.5 1 21.9 1 22.01 21.7

  19.5 18.6 19.0 19.8 18.2 1 18.9 1 19.4 20.41 20.4

  250 17.3 18.7 19.3 20.0 18.9 1 18.5 1 18.3 19.41 19.9

  315 17.7 19.2 19.7 18.6 19.7 1 19.9 1 20.6 1 21.31 20.6

  400 23.9 24.2 23.8 24.7 24.8 1 24.4 1 23.9 1 25.31 24.6

-I I-

  In Table II, the difference 204R of the arithmetic means of the indices R concerned for glazing with neighboring thicknesses associated in pairs has been shown, the average being carried out for all the frequencies of the

Table I.

TABLE II

II | n | AR glazing [

I_ _! _ _ _ _ _ _ _ _ _ _ _ I

  I I I 301 1 1 3,9 + 4,1 and 3,9 + 4,2 - 0,030 I 2I 3,9 + 4,2 and 3,9 + 4,3 + 0,186 I 3 I 3,9 + 4 , 3 and 3.9 + 4.4 + 0.186 i 4 * 3.9 + 4.4 and 3.9 + 4.5 + 0.143 I 5 I 3.9 + 4.5 and 3.9 + 4.6 + 0.014 351 6 1 3.9 + 4.6 and 3.9 + 4, 7 + 0.757 I 7 I 3.9 + 4.7 and 3.9 + 4.8 - 0.257

I_ _ _I [__ _ _ _ _ _ _ _ I _ _ _ _

  There is thus stagnation of the improvement for the combinations n i and 5, a normal progression for 2, 3 and 4 but a quantitative jump for the combination 6 while the combination 7 presents an unexpected regression. Such behavior does not find an explanation in the mass law nor in the usual theories of acoustics. Figure 2 shows at 4 the curve of sound reduction index for glazing 3.9 (12) 4.6 and in 5 the same curve for combination 3.9 (12) 4.7

  accounts for the same surprising phenomenon.

  Figure 3 and Figure 4 show the consequences

  of these findings on overall acoustic performance

  bales of the corresponding products. FIG. 3 shows the acoustic loss indices for a

  road noise calculated according to standard NF, S31-051. In ab-

  the thickness of the second glass, the first having a thickness of 3.9 mm. The air gap is 12 mm. In 6 we see the results for glazing installed without chassis. In 7 are the indices obtained when the glazing is mounted in an aluminum window of a good seal but a medium acoustic performance, it is a window equipped with opening "à la française" carried out

  with profiles of the ALCAN brand, type T 2000.

  Curve 8 corresponds to the results obtained with a good polyvinyl chloride (PVC) window. She was

  equipped with a double seal. Its openings are in French

  However, it is made of COMBIDUR VK

KNOERLING brand.

  Similarly, in Figure 4, there is shown the value of Rw calculated according to ISO 717 Part 3, for the same combinations of glazing and windows. We see at 9 the glazing alone, at 10, the same aluminum window and at 11, the same good PVC window. The study of Figures 3 and 4

  confirms what was shown in Table II, it is

  tate - especially for the glazing alone and especially for Rroute route - a quantitative jump when the thickness of the second glass reaches a value equal to that of the first increased by%. This effect is less clear for the windows because of the incidence of the constitution of the window itself and for Rw because in the calculation of this magnitude one rounds

  values to the whole decibel lower.

  The previous effects, studied in detail in the case of glazing filled with dry air were also verified in the case where the interior space is filled with a mixture of heavy gas and air. The values are as follows: glazing 3.9 (12) 3.9 filled Rroute = 24.6 dB (A) of an Air / SF6 mixture in the proportion 20/80 t 32 dB glazing 3.9 (12) 4 , 7 filled Rroute = 26.1 dB (A) of the same mixture (Rw = 34 dB

  The benefits of glazing according to the

  are obvious: it is interesting to obtain a

  acoustic result given with the thinnest glass

  sible: economy of material and therefore of weight which makes it possible to lighten the carrying structure and especially possibility to use frames bearing carriers of identical windows for the normal variants and the acoustic variants. Thus a "normal" glazing consisting of two 3.9 mm glasses associated with a 13 mm air gap would have a thickness close to the acoustic glazing consisting of a separate 3.9 mm glass a glass of 4.7 mm by a blade

  12 mm of air. The use and especially the profunda-

  The amount of rebate required for both types of glazing would be exactly the same. But the good quality PVC window with these windows would see its acoustics improve significantly since the Rroute would go from

  29.4 to 32.6 dB (A) and the Rw from 35 to 37 dB.

Claims (7)

  1. Thermal and acoustic protection glazing   consisting of two glass sheets of different thicknesses   rent separated by a blade of air or other gas,   characterized by the fact that the difference in the thicknesses   brought to the thinnest glass is less than 26%.   2. Glazing according to claim 1, characterized in that   that the difference in thicknesses is less than 22%.   3. Glazing according to claim 1 or claim   2, characterized in that the difference in thicknesses is greater than 20%.   4. Glazing according to claim 2 or the claim   3, characterized in that the thickness of the glass most   thin is at most equal to 4 millimeters.   5. Glazing according to one of the preceding claims,   characterized in that the space separating the glass sheets comprises a gas having a molecular weight greater than 100. 6. Glazing according to claim 5, characterized in that   that the gas is sulfur hexafluoride.   7. Glazing according to claim 6, characterized in that   that SF6 is in a proportion greater than 30%.