EP2888107A1 - Motor vehicle glazing - Google Patents

Abstract

The invention relates to laminated glazing for motor vehicles, including a convex outer tempered glass sheet and a thin inner glass sheet that is also tempered, wherein said sheets are assembled together using a sheet of thermoplastic intermediate material. Said glazing is to receive a mechanical attachment and/or mobilization means, and a portion of the outer sheet of said glazing is not covered by the thin inner sheet, the attachment of the glazing being carried out in the area that is not covered by the thin sheet.

Description

 Auto glass

The invention relates to laminated automotive glazings.

 Automotive windows are subject to increasingly demanding performance and often difficult to reconcile. This is particularly the case of windows which by their location in the vehicle may be subjected to special mechanical stresses. For example, the side windows of doors that are not engaged in a frame that surrounds them, as in some cabriolets, must be able to withstand without significant effort efforts, for example when slamming the door.

 Side windows usually consist of monolithic glass sheets more or less thick. But the manufacturers, for the most sophisticated vehicles, wish to have windows offering the best existing properties. These include glazing with acoustic attenuation, anti-burglary, athermic properties, etc. In practice to lead to these windows it is necessary to have laminated products.

 Moreover, the mechanical strength for the cases envisaged according to the invention requires that the laminated glazings offer a resistance which is that of tempered glasses.

 The door side windows are very usually mobile and must be driven in their movement by mechanical parts which are attached to their lower part concealed in the door.

The fixing of monolithic sheets can be obtained by bonding riders overlapping the lower edge of the glazing. The rider is optionally glued but most often it is fixed by means of devices that use a shaping of the glass sheet, including holes, which allow the passage of nuts, rivets or the like, which ensure a particularly strong assembly. For laminated glazing, these modes of attachment are not desirable insofar as the pressure initially exerted on the glazing can lead to the deformation of the glazing. interlayer sheet material, and ultimately eventually to a loosening of this fixation.

 Apart from the side windows, the fixing of elements on a glazing, for example the wiper system of the rear window, raises problems of a similar nature. The system must be securely attached and lead to a strong pressure exerted on the glazing at the location of the passage for example of the axis of the system.

 The glass sheets before quenching can undergo the necessary work for this fastener forming without risk of rupture, including the drilling of holes. Conversely, leaves once soaked can not. When the glazing is monolithic shaping for these fasteners is performed before the quench which follows immediately to the bending operations. Associating two soaked sheets whose shaping was undertaken before their bending / quenching faces a problem of perfect recovery of the shaped parts. The holes in each of the leaves must be perfectly of the same axis, which in practice is not possible for the sheets having undergone this bending. A slight offset of the axes necessarily occurs exposing the sheets to difficulties that may lead to the weakening of the assembly.

 The invention proposes to respond to these difficulties in the manner forming the subject of claim 1.

 By their composition, the glazings according to the invention can offer the advantages of laminated glazing while at the same time guaranteeing the necessary mechanical strength of the hardened monolithic glazings.

The two leaves of the assemblage are very different in their structure. The curved outer sheet is sufficiently thick so that when assembled to the inner thin sheet, it imposes its shape on the latter. It is tempered or semi-tempered to provide the necessary resistances. The tempered glasses exhibit, under standard conditions, an instantaneous flexural resistance of the order of 60 MPa; the semi-tempered glasses offer for the same size only a value of the order of 40 MPa. The assembly of a curved sheet with a sheet that is not, or whose curvature is not significant, is subject to conditions that take into account in particular their respective characteristics, starting with their thickness. If applicable to "light" laminated glazing, these conditions are detailed in particular in application PCT / EP2012 / 061557 filed on June 18, 2012 incorporated herein by reference. The conditions on the other hand, whether or not the glazing is lightened, are detailed below.

 If the curvature of the assembled sheets is significant, the ratio of the thicknesses of the curved sheet to that which is not should preferably be at least 3/1 and advantageously at least 4/1. If there is no upper limit to this ratio, the practical conditions related to the total thickness of the glazing and those concerning each of the sheets, nevertheless lead to a ratio which in practice does not exceed 12/1.

 The ratio of the thicknesses is advantageously more important than the radius of curvature imposed on the thin sheet, substantially flat before assembly, is smaller. This is the case for example when the radius of curvature is less than 3m and especially if it is less than 1.5m.

 The PCT application mentioned above refers in particular to the fact that the induced surface stresses in the thin sheet by its assembly to the thick sheet, generally should not exceed about 50 MPa. The constraint supported is a function of the curvature and is all the stronger as the radius of curvature is smaller. The application in question gives as an example the stresses induced for different thicknesses as a function of this radius of curvature.

 For the models for which the manufacturers do not seek the lightening of the glazings, the thick sheets according to the invention can go up to 5mm and more. Conversely for glazing aimed at a limited weight, the thickness of the quenched sheet preferably does not exceed 2.4 mm and advantageously not 2.1 mm.

For the thin sheet the choice of its thickness is conditioned by its ability to conform to the curvature of the thick sheet. The lower its thickness, the easier it is to impose this deformation. The thickness of this leaf is advantageously at most 0.8mm, and preferably at most 0.6mm. It is possible to produce sheets as thin as 0.1mm, however for the convenience of implementation it is preferred that the sheet has a thickness of at least 0.2mm.

 The shaping of very thin glass sheets is delicate and poses problems of reproducibility. Insofar as the final curvature of the laminated glazing is that imposed by the thick sheet, it is not necessary nor advantageous that the thin sheet has a curvature before assembly.

 To give the sheets the mechanical strength which, at least for the thin sheet, allows them to undergo the bending imposed on the assembly, without the risk of exceeding the tolerable stresses, the threshold of these stresses is advantageously raised by the quenching these leaves.

 The quenching of glass sheets is most often carried out thermally for reasons including economy, taking advantage of the temperature reached in the production process. The thermal quenching is obtained by rapid cooling, by blowing air at room temperature on the faces of the sheet. The cooling is exerted first on the surface whereas in the thickness of the sheet the temperature decreases more slowly. This operation is that which leads the thick sheet to the quenched or semi-tempered state according to the conditions of implementation of this operation.

 For very thin leaves, surface and core temperatures often do not have a sufficient gradient during forced cooling to reach the desired stress level. For the reasons explained above, the thin sheet is preferably chemically quenched. This type of quenching makes it possible to obtain the stresses sought even on thin sheets. The chemical quenching is carried out under the traditional conditions for this type of treatment, in particular by exchange of sodium ions by potassium ions on the surface of the sheet.

The arrangement according to the invention which carries over to the single thick sheet fixing and possible shaping, avoids the difficulties related to lamination and the presence of the thin sheet. The glazing in its non-flaky part behaves as a monolithic glazing, and for the rest retains all the features that can be those of laminated glazing.

 Laminated glazings have been previously described in which the two sheets are not strictly coextensive. This is the case for example EP1171294 patent on a glazed roof comprising a series of photovoltaic cells incorporated in a laminated part, the roof further comprising a monolithic portion without cells. The presence of the laminated part in this case is intended to incorporate these functional elements into a structure that protects them. The sheet which covers only a part of the glazing does not have a particular thickness. Still in this prior embodiment the outer sheet in its non-laminated portion is not intended for fixing the glazing. The roof glazing is usually fixed by gluing on the bodywork, both by the laminated part and by that which is not.

 It is also known previously laminated assemblies in which the edges of one of the glass sheets are slightly set back from those of the other sheet. This arrangement is envisaged for example to glue the glazing through the sheet on the uncovered edge. As in the previous case, the arrangements described do not include the use of sheets assembled under the conditions of the invention.

 The structure of the glazing according to the invention comprising a partial lamination, allows the fixing of the glazing even if it requires shaping as the presence of holes cooperating with mechanical means. The dimensions of this non-laminated portion may be relatively limited compared to the total surface of the glazing. It is not necessary, or even desirable, for this part to extend beyond what is actually necessary to provide the fastening means for the thick sheet. Conveniently the non-laminated portion preferably does not represent more than 20% of the area of the thick sheet and particularly preferably not more than 10% of that area.

To properly dispose of the glass fixing means the non-laminated surface is nevertheless of a certain size. It is preferably at least 0.5% of the area of the largest leaf, usually at least 1% of that area.

 The presence in the glazing according to the invention of a sheet which undergoes no heat treatment other than that related to the assembly of the sheets with their interlayer, offers certain conveniences for the insertion of means leading to additional functionalities. This is particularly the case for means sensitive to high temperatures. The assembly is carried out in a traditional manner and the temperatures reached are not greater than those required to allow the bonding by the interlayer sheet. These temperatures are usually of the order of 120-130 ° C, and do not usually exceed 150 ° C.

 Starting from these conditions, it is possible to use the thin sheet as a support, in particular for thin layers sensitive to heat. This is for example the case of low-emissive layers comprising metal layers reflecting IR. The deposition of the layers in question is carried out by sputtering under vacuum. In the implementation of these methods, if the sheet is so thin that it can not itself guarantee its flatness during the deposition, this sheet can be placed on a thicker sheet which serves only to support the thin leaf.

In thermal treatments of the tempering bending type, the temperature rises to around 650-700 ° C. At these temperatures the metal layers, in particular based on silver, must be subject to special protections, sometimes difficult to achieve. The application of the layers in question on a previously curved glass sheet raises other problems, including uniformity of the coating such that it is generally preferred to apply these layers on the flat sheets, and therefore to submit these layers the thermal conditions of shaping the glass sheet. But in this treatment the properties of the layers can undergo significant alterations, the prevention of which requires that these layer systems have very specific structures. Conversely, the application of relatively heat-sensitive layers on the sheets which according to the invention do not undergo these treatments, avoids any alteration of these layers. In practice, if one wants to have this type of layers, both solutions are possible. The layers are on the thick sheet, or more precisely on the part thereof which is then taken in the lamination in contact with the interlayer, and in this case they are subjected to bending / tempering operations, or these layers are on the thin sheet and on the face of it which is brought into contact with the interlayer.

 The invention is described in detail with reference to the drawing board in which:

 - Figure la is a schematic front view of a glazing according to the invention; - Figure lb is a side view of a section along A-A of the glazing of Figure la;

 - Figure 2 is a partial sectional view of the portion of a glazing according to the invention showing the positioning of the glass fixing means.

 Figure la shows a movable side glazing 1 for sliding in or on slides disposed on the body of a vehicle. In its movement the glazing once lowered, for example, enters a door of the vehicle. The guiding of the glazing can if necessary be carried out only from the slides integrated in the door. Especially for these "frameless" glazings, the mechanical strength must be ensured. In the fully raised position the lower part of the glazing remains hidden by this door, for example to the level represented by the dotted line b-b.

The glazing, as shown in Figure lb, comprises an outer sheet 3, tempered glass or semi-tempered. This sheet is curved before assembly to the other components of the glazing. A second glass sheet 10 is associated with the sheet 3 by means of an interlayer sheet 6 of a thermoplastic material traditionally used for this purpose. The thermoplastic sheet is for example a polyvinyl butyral (PVB) sheet. The sheet 10 owes its curvature to its assembly with the sheet 3. Before it, the sheet 10 is substantially flat. The deformation imposed by the assembly is maintained by the strong adhesion of the interlayer sheet to the two glass sheets and by the resistance of the relatively thick sheet 3 with respect to the sheet 10. The respective thickness of the sheets for a "lightened" glazing is, for example, 2.1 mm for the sheet 3, and 0.4 mm for the sheet 10. The interlayer sheet may be made of PVB of standard thickness, for example of 0, 76mm or 0.38mm. But other traditional spacers are also usable, including EVA, which are of similar thickness or less.

 The total thickness of glass in this glazing is thus 2.5 mm. The traditional monolithic side windows have a thickness of about 4mm or, for the thinnest, of the order of 3.2mm. The laminated part of the glazing according to the invention is therefore relatively lighter than for traditional monolithic glazings.

 As shown in the figures, the lamination does not cover the whole of the glazing 1. The thin sheet 10, and the interlayer sheet associated with it, leave a part 4 of the sheet 3 uncovered.

 The part of the glazing 1 which is not hidden by the bodywork, and which is located above the dotted line b-b, is entirely laminated. It therefore preserves the glazing all the expected properties of this part exposed to mechanical hazards such as shocks, that these come from the outside as well as from inside the vehicle. In particular the glazing has the anti-burst or anti-ejection properties traditionally associated with laminated glazing. It also offers the acoustic properties of these laminated glazings, properties which benefit in particular from the difference in thickness of the glass sheets composing this glazing, and which can be further improved by the use of specific spacers offering increased acoustic attenuation. These spacers are for example sheets composed of three layers of PVB, the central layer being over-plasticized with respect to the two layers in contact with the glass sheets.

In the part of the glazing that is hidden from view by the bodywork, the lamination is not complete. Part 4 comprises only the sheet 3. It is in this part that the sheet 3 receives the fixing means. In the representation of the figures, the sheet 3 is shaped. It comprises a cylindrical hole 5 passing through the sheet 3. This hole 5 is formed before the quenching of the sheet. FIG. 2 illustrates, as an indication, a method of fixing the glazing unit 1. The part 4 of the glazing serving to fix it is taken between two plates 7, held tight on the glass sheet 3 by a fixing means 9, in the representation rivet. But all similar means are suitable. Between the plates 7 and the glass sheet, a sheet 8, and a sleeve 11, of resilient material, avoid contact of the glass 3 with the metal of the plates 7.

 In the chosen representation a single through hole 5 is shown. Several fixing points of the same nature can be arranged in the part 4 of the glazing 3.

 If the shaping presented is a simple through hole it is also possible to replace it with any equivalent means, for example a blind hole in which is inserted a stud or pin shape and corresponding dimensions, worn or integral platens tightened on the glass by means disposed beyond the bottom of the sheet 3 and not shown.

 Figure 2 does not show the traditional means articulated on the plates 7, which are connected to the mobilization devices of the glazing.

Claims

1. An automotive laminated glazing comprising a curved hardened outer glass sheet and a thin, also quenched inner sheet, said sheets being assembled by means of a sheet of thermoplastic interlayer material, glazing intended to receive mechanical fixing means and / or mobilization, glazing in which a portion of the outer sheet is not covered by the thin inner sheet, the fixing of the glazing being performed in the area not covered by the thin sheet.  2. Glazing according to claim 1 wherein the ratio of the respective thicknesses of the outer sheet to the thin sheet is at least 3/1 and preferably at least 4/1.  3. Glazing according to claim 1 or claim 2 wherein the outer sheet has a thickness of not more than 5mm.  4. Glazing according to one of the preceding claims wherein the thin sheet has a thickness of not more than 0.8mm and preferably not greater than 0.6mm.  5. Glazing according to one of the preceding claims wherein the thin glass sheet has a thickness of not less than 0.2mm.  6. Glazing according to one of the preceding claims wherein the thin glass sheet has no significant curvature before assembly with the curved outer glass sheet.  7. Glazing according to one of the preceding claims wherein the thin glass sheet is chemically quenched. 8. Glazing according to one of the preceding claims wherein the thin glass sheet is coated on its side facing the spacer of a set of functional layers conferring athermic properties. 9. Glazing according to any one of the preceding claims wherein the non-covering portion of the sheets does not represent more than 20% of the surface of the outer sheet, and preferably not more than 10% of this surface.  10. Glazing according to one of the preceding claims wherein the non-covering portions of the sheets is at least 0.5% of the surface of the outer sheet, and preferably at least 1% of this surface.  11. Glazing according to one of the preceding claims wherein the outer sheet comprises in the non-laminated portion one or more holes for receiving means for fixing / mobilization of the glazing.  12. Glazing according to one of the preceding claims constituting a mobile side glazing.  13. Glazing according to one of claims 1 to 11, serving as support for reported elements requiring shaping of the glazing.