Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60J—WINDOWS, WINDSCREENS, NON-FIXED ROOFS, DOORS, OR SIMILAR DEVICES FOR VEHICLES; REMOVABLE EXTERNAL PROTECTIVE COVERINGS SPECIALLY ADAPTED FOR VEHICLES
  • B60J1/00—Windows; Windscreens; Accessories therefor
  • B60J1/008—Windows; Windscreens; Accessories therefor of special shape, e.g. beveled edges, holes for attachment, bent windows, peculiar curvatures such as when being integrally formed with roof, door, etc.

Definitions

• FIG. 1 illustrates an embodiment of a motor vehicle 2 comprising numerous glazings 4.
• a large glazed area of a vehicle is a growing trend of embodiment, this being mainly related to the visual comfort that such an embodiment can provide to the car. user.
• Another growing trend is the production of lighter vehicles, which are interesting from an economic point of view for the user, because it contributes to lower fuel consumption.
• the windows of a motor vehicle are a significant part of its mass.
• the ratio between the mass of a glass automotive glass and that of a plastic automotive glazing is of a factor substantially equal to two, of equivalent thickness.
• the acoustic insulation of a glazing as an acoustic barrier has different characteristics on the different audible frequency ranges.
• plastic glazing because of its lower density, offers poorer acoustic performance at low audible frequencies; At equivalent thickness, and also by its lower density, the plastic glazing has a drop in acoustic performance around 10kHz, where for glass glazing the fall occurs around 4kHz. It is therefore desirable that the realization of a motor vehicle with lightened glazing can satisfy an acceptable sound insulation of the vehicle, the lightening thereof should not be at the expense of the associated manufacturing cost.
• the invention aims to facilitate the realization of a motor vehicle with plastic glazings so as to reduce the total mass of the vehicle and in an economically viable perspective. More particularly, the invention aims to improve the acoustic comfort of a vehicle with such glazing, more particularly to reduce the acoustic transmission over the frequency range 5kHz to 10kHz.
• the invention relates to a plastic glazing intended to be mounted in abutment on its periphery, in particular on a motor vehicle body, remarkable in that the glazing comprises at least one portion of variable thickness, said portion being intended to modify the speed of propagation of vibratory waves in the glazing so as to reduce the acoustic transmission of said glazing over the frequency range 5 kHz to 10 kHz.
• the glazing is made of material, preferably polycarbonate or preferably polymethyl methacrylate.
• the portion has a thickness varying from 15% to 40% of the average thickness of the glazing.
• the portion extends essentially to the periphery of the glazing, said portion being of variable thickness in a peripheral direction, said periphery having a width of between 1% and 15% of the largest dimension. glazing.
• the portion is of variable thickness, moreover, in a direction orthogonal to the peripheral direction.
• the portion extends in the central part of the glazing or on the entire surface of the glazing.
• the glazing is of an average thickness of between 4 mm and 8 mm, the acoustic attenuation measurement of the glazing being improved from 0 to 5 dB over the frequency range corresponding to the acoustic coincidence zone of the glazing.
• the invention also relates to a process for shaping a plastic glazing by injection molding, remarkable in that the glazing is in accordance with the invention.
• the invention also relates to a tool, remarkable in that it is configured to implement the method according to the invention, said tool comprising a mold having a convex shape so as to shape the inner face of the glazing said face being intended to be inwardly of a motor vehicle.
• the invention also relates to a motor vehicle, remarkable in that it comprises at least one plastic glazing according to the invention, said glazing being mounted on the vehicle body preferably by gluing.
• the measurements of the invention are interesting in that they make it possible to reduce the noise in the vehicle over the critical range of high frequencies from 5 kHz to 10 kHz. Indeed, the thickness variation in the glazing changes the wavelength, and speed, of the bending wave in the glazing, so as to reduce the loss of transmission losses of the sound waves.
• the acoustic barrier of the improved plastic glazing facilitates the realization of a lighter motor vehicle, while reducing the transmission of acoustic waves from the outside of the vehicle compared to known plastic windows.
• FIG. 2 is a block diagram illustrating the loss of sound transmission through a glazing unit
• FIG. 3 is a principle graph illustrating the drop in the transmission loss through the glazing unit of FIG. 2;
• FIG. 4 is a radial sectional view of a glazing unit of FIG. 1 and an enlarged view of two portions of the glazing unit;
• FIG. 5 is a graph illustrating the reduction of the loss of transmission losses of a glazing unit according to a preferred embodiment of the invention.
• FIG. 6 is a front view of a glazing of the vehicle of Figure 1 according to a preferred embodiment
• FIG. 7 is a sectional view of a periphery of the glazing of Figure 6;
• FIG. 8 is a radial sectional view of the window of Figure 6.
• Figure 1 is a view of a vehicle 2 comprising at least one outer glazing 4 according to the invention.
• the glazing 4 is supported on the body and fixed by gluing on a body rebate.
• the glazing 4 may be a quarter panel glazing or roof or rear window.
• the glazing 4 is of organic main material 6, it is favorably plastic so as to lighten the vehicle. It is for example polycarbonate or polymethylmethacrylate.
• FIGS. 2 and 3 illustrate known principles of the acoustic barrier as well as the fall in the acoustic performance of a glazing over a critical frequency range, phenomena that must be understood in order to understand their effect on the sound insulation of a vehicle.
• FIG. 2 shows the glazing 4 of the vehicle 2, glazing above which is represented a first arrow illustrating an external sound power and below which is shown a second arrow, of smaller size, illustrating a sound power transmitted inside of the vehicle 2.
• the difference in size arrows schematizes transmission losses (in dB) "transmission loss" of sound power through a glazing, specifically a solid and airtight glazing. These losses are embodied by a noise reduction between the outside and the inside, the glazing becoming commonly called an acoustic barrier.
• dB transmission loss
• Figure 3 illustrates the phenomenon of falling transmission losses of a glazing, in other words a greater passage of noise through the glazing, this phenomenon occurring according to the glazing over a certain critical frequency range f.
• the image on the critical frequency zone C (in Hz) generally illustrates the suddenness of the phenomenon.
• the low point of the loss loss corresponds physically to a spatial and frequency coincidence of the bending waves (A f i ex ) in the glazing and acoustic waves (A air ) in the air enveloping the glazing.
• the plastic glazing in the context of the invention, is configured to provide a reduction in the noise transmission in the acoustic coincidence zone, more precisely in this frequency range of 5kHz to 10kHz more audible .
• Figure 4 is a radial sectional view of the glazing unit 4 according to the invention.
• the image also includes enlargements of two regions of the glazing.
• the glazing 4 comprises at least one portion 8 of variable thickness T.
• AD (shown in the image) corresponds to the variation of the variable thickness T in the portion 8 of the glazing 4.
• the quality of the acoustic barrier of the glazing varies, as seen above, according to the speed V of propagation of the vibratory wave (or bending) in the glazing, itself dependent on the frequency of the sound wave as well as the flexural wavelength in the glazing. However, the non-uniformity of the thickness of the glazing directly influences this speed V.
• the bending wave (A f i ex ) in the glazing 4 is proportional to the square root of the thickness T of the glazing 4.
• the propagation velocity V in the portion 8 is also not.
• the portion 8 not being limited in the glazing 4, the propagation velocity V may not be uniform over the entire surface of the glazing 4.
• the portion 8 may extend in the central portion 12 of the glazing 4, it may also extend over the entire surface 14 of the glazing 4 or on its periphery 20.
• AD is 15% to 40% of the average thickness 16 of the glazing 4.
• the sound attenuation measurement of the glazing can be improved up to 5 dB over the frequency range 5 kHz to 10 kHz.
• the glazing 4 is preferably made by a molding process by injection molding.
• a tool is configured to implement the method, it comprises a mold having a convex shape so as to shape the inner face 18 of the glazing 4, said face being intended to be inwardly of a motor vehicle.
• FIG. 5 illustrates by a graph the reduction of the drop in transmission losses of a glazing unit 4 according to the invention. More precisely, a first graph (in dashed line) represents the transmission losses of a conventional plastic glazing, the second graph (in solid lines) representing the transmission losses of a plastic glazing unit 4 according to the invention.
• the thickness of the reference glazing is 6mm, that according to the invention is of a thickness ranging from 4mm to 8mm.
• the second graph on the contrary remains on a sound barrier plateau equivalent to the acoustic reduction achieved for frequencies between 4kHz and 5Hz.
• Figure 6 is a front view of the glazing 4 according to a preferred embodiment.
• the portion 8 of variable thickness T extends to the periphery 20 of the glazing 4. It extends in this case over a portion of the periphery 20. Alternatively, the portion 8 may extend over the entire periphery 20.
• the portion 8 at the periphery 20 may be of a width 22 between 1% and 15% of the largest dimension 24 of the glazing 4.
• the portion 8 is of variable thickness T, in addition, in a direction orthogonal to the peripheral direction. The portion 8 then extends into the central portion 12 of the glazing 4. In a preferred embodiment the portion 8 may also extend over the entire surface 14 of the glazing 4.
• Figure 7 is a sectional view along the periphery of the glazing 4 according to a preferred embodiment.
• the variation in thickness AD1 of the portion 8 of variable thickness T extends in a peripheral direction.
• Figure 8 is a radial sectional view to the glazing 4 according to a preferred embodiment.
• the variation in thickness AD2 of the portion 8 of variable thickness T extends in a direction orthogonal to the peripheral direction.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Vehicle Interior And Exterior Ornaments, Soundproofing, And Insulation (AREA)
• Window Of Vehicle (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=51260960

Family Applications (1)

Country Status (4)

Family Cites Families (6)

• 2014
  • 2014-02-28 FR FR1451624A patent/FR3018049B1/fr not_active Expired - Fee Related
• 2015
  • 2015-01-22 CN CN201580011193.3A patent/CN106061778B/zh not_active Expired - Fee Related
  • 2015-01-22 WO PCT/FR2015/050154 patent/WO2015128554A1/fr active Application Filing
  • 2015-01-22 EP EP15704353.0A patent/EP3110640A1/de not_active Withdrawn

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