MXPA97002378A - Windshield which can be heated electricame - Google Patents

Abstract

A windshield (1) made of laminated glass is provided in the region from which the windshield wipers are placed at rest, with electric resistive heating wires. The resistive heating wires are interspersed in the thermoplastic intermediate layer of the laminated glass pane. They are arranged in the form of wire circuits (2) fitted together and mounted in parallel. The ends (3, 4) of the wire circuits (2) are welded to pickup conductors (5, 6), made of a thin sheet of metal, which are disposed very close to each other at the edge of the windshield and are connected to each other. to electrical connection conductors (7,

Description

WINDSHIELD WHICH CAN BE HEATED ELECTRICALLY DESCRIPTION OF THE INVENTION The present invention relates to a windscreen made of laminated glass, which is provided in the region where the windshield wipers are placed at rest, with electrical heating resistive wires, mounted in parallel and embedded in the thermoplastic intermediate layer, whose wires they are in contact with films of a thin sheet of metal that act as collection conductors, also embedded in the intermediate layer and connected to the conductors to supply current. The heated, laminated glass windscreens for which the heated, formed field of the parallel heating wires is limited to the windshield wiper region, are known from EP 0,032,139 Bl. In this case, thin strips of a thin sheet of copper, which are arranged on both sides of the heated field, act as collection conductors. The electric power supply conductors for these collection conductors usually leave the laminated glass pane at one end of the collection conductors, i.e., the points which are far apart. It is also known to manufacture the connection conductors for the two collecting conductors, which are arranged on the two sides of the heated field at the end of the resistive wires which extend in a straight line that leaves the glass of laminated glass in points which are very close together However, a link conductor, which connects the electrical connection point in at least one of the collection conductors, has in such a case to be provided inside the laminated glass pane, ie also embedded in the thermoplastic intermediate layer. . Usually, the same strips of thin sheet of copper thinned as for the collection conductors, are used for this purpose. The link conductors are arranged between the pick-up conductors and the electrical connection point along the lower axis of the windshield. In this mode, the electrical connection after the windshield has been adjusted is made easier, because in that case it can be achieved by using two individual male plugs. Apart from the fact that the arrangement of the link conductors represent a relatively expensive additional work operation, the link conductors are optically distracting, due to their metallic surfaces. This is because they are coated, by printing, with an opaque layer of ink on one of the two glass sheets of the laminated glass pane. This also represents additional labor costs. The object of the invention is to provide an electrically heatable windscreen of the type mentioned, which is simpler in its structure and in which, in particular, the optical distraction metal link conductor can not be seen. In addition, the new windshield is capable of being manufactured at a lower overall cost and in a shorter amount of time. This object is achieved in accordance with the invention in that the two thin sheet metal strips which act as the collection conductors are disposed very close and that the heating resistive wires extend in the form of circuits between these picking conductors. In the arrangement of the heating wires according to the invention, the optically distracting conductors forming a link between the point of the electrical connection and the suitable pick-up conductors are absent. The lengths of the thin sheet sheet acting as the picking conductors can preferably be arranged directly on the lower edge of the windshield, such that the thin metal distraction strips are no longer present along the length of the sheet. the side edges of the windshield. Because the lower edge of the windshield is free of long strips of thin sheet metal distraction, it is also possible to supply with the printing of a coating layer. The modalities, developments and other preferred advantages of the invention will become clear from the dependent claims and from the following description of the various embodiments, which is given with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a windscreen that includes the electrical connection conductors at the lower edge of the half of the glass; Figure 2 shows a windshield including the electrical connection conductors at the lower edge in a corner region; Figure 3 shows a windshield including collection conductors disposed along a side edge; Figure 4 shows a windshield including an additional heating circuit along a side edge, and Figure 5 shows a windshield including additional heating circuits along both side edges. The windscreens represented in the figures consist of laminated glass and consist of two individual glass sheets, which are joined together by a thermoplastic intermediate layer, which as a rule is made of polyvinyl butyral. In the lower third, namely in the region in which the windshield wipers are placed at rest, the windshields each have a field which can be electrically heated. In this heatable field, the resistive heating wires are arranged in the thermoplastic intermediate layer, in the new shape. The methods for applying the resistive heating wires in the form of a circuit are known per se. In a known method, the resistive wire is pushed into the thermoplastic film before the laminated glass pane is manufactured, using a hot tool, for example a hot press cylinder. In another known method, the resistive wires which are arranged in an intermediate backing film in the desired arrangement and are fixed thereto with a layer of adhesive, which is made of the same substance as the thermoplastic intermediate layer. The collection conductors and, as appropriate, the conductors for supplying current may also already be arranged in this intermediate backup film and be connected to the resistive heating wires. With the help of the intermediate backing film, the wire arrangement is transferred onto the thermoplastic intermediate layer or onto one of the two sheets of glass. After the wire arrangement on the thermoplastic intermediate layer or on one of the glass sheets has been fixed, the intermediate backing film is removed. The glass laminated glass is then manufactured by applying heat and pressure. Thin tungsten wires with a relatively high electrical resistance are usually employed for the resistive heating wires in the heatable crystals. The use of such wires with a high electrical resistance is, in such cases, advantageous, because the length of the wire is predetermined by the distance separating the collection conductors, which correspond to the width dimension of the heated field in the case of the known modalities. In the heatable windshields according to the invention, the individual resistive heating wires mounted in parallel, however, are due to their arrangement in the form of a circuit, at least twice as long as in the known heatable windshields. This means that in the windshields according to the invention, use can be made of heating wires which have a greater electrical conduct and thus, for example, heating wires particularly of copper. This leads not only to a reduction in material costs, but also in particular, to the fact that the difficulties associated with the welding operation of the tungsten wires on the collection conductors is avoided. The copper wires, which are covered with a black lacquer in such a way that the reflection of the light from these wires is avoided, have proven to be suitable for the purposes of the invention. Particularly advantageous is the use of blackened copper wires, which are covered with a lacquer, which has no problems when welding the wires to the collection conductors, but has good surface tinning properties, which means that it does not need to be removed before the welding operation. In the embodiment shown in Figure 1, the heating wires 2 are arranged in the windscreen 1 in the form of nested circuits and one in the other, these circuits which are axially symmetrical with respect to the median line M-M. In the lower half of each wire circuit, the two ends 3, 4 of each wire circuit flex downward at right angles. They are then welded to the lengths of the copper foil 5, 6. The lengths of the copper foil 5, 6 represent the collection conductors for the conduction circuits mounted in parallel and are arranged at a short distance apart from the two individual glass sheets of the laminated glass pane in the thermoplastic intermediate layer in close proximity to the edge in the lower side half of the windscreen. The lengths of the copper foil 5, 6 are directly connected to the flat cables 7, 8 which leave the laminated glass pane as they are and are provided at the end with the appropriate connecting wires or connection plugs. The lengths of the copper thin sheet 5,6 can also be formed as a piece with the flat cables 7, 8 using the same thin copper sheet, the flat cables 7, 8 coming out of the laminated glass pane which is adequately provided with insulating layers of plastic that support the appropriate tension. The windshield 10 shown in Figure 2 is once again provided in the lower third with a heated field, which covers the same area as the heated field in the manner described in the foregoing. In this case also, the heating wires 12 extend substantially across the entire width of the windshield in an orientation parallel to the lower edge of the windshield. The heating wires are once again arranged in the form of circuits fitted together. The two ends of each wire circuit in this case, however, that flexes down near a lower corner of the windshield. The end regions 13 of the wire circuits are welded to a length of the copper foil 15 and the end regions 14 of the wire circuits are welded to a length of the copper foil 16, the lengths of the thin sheet of copper 15, 16 represent the collection conductors for the conductive circuits mounted in parallel. The lengths of the copper foil 15, 16 connected to the appropriate flat cables 17, 18 are arranged directly adjacent to the edge of the glass the corner region of the windshield, such that the electrical connection is carried out this time by means of of an appropriate plug in this corner region of the windshield. The embodiment shown in Figure 3 shows a windshield 20 in which the resistive heating wires 22 are once again arranged in the form of horizontally oriented U-shaped circuits, fitted together. In this case, however, the lengths at the end of the wire circuits are not bent. On the contrary, they maintain their horizontal orientation and are welded to two conductors 25, 26 of current collection in the form of strips. These collection conductors 25, 26 are disposed very close to each other, parallel to each other, along the lateral edge 24 of the windshield 20. The length of the collection conductor 26 is only about half that of the directly adjacent collection conductor 25. to the side edge 24, which means that the collection conductor 25 is connected to the upper halves of the wire circuits and that the collection conductor 26 is connected to the lower halves of the wire circuits. The electrical connection conductors 27, 28 that come out of the laminated glass pane 21 once again can be formed of flat cables. Figure 4 shows a windscreen 30 which is once again provided in its lower section, in the region in which the windshield wipers are placed at rest, with the wire circuits 31, 32 positioned horizontally and fitted together. The ends 33, 34 of these wire circuits 31, 32 are once again welded to the current collecting conductors 35, 36, which are arranged directly at the lower edge of the windshield in the thermoplastic intermediate layer and are connected to the conductors 37, 38 for electrical connection in the form of flat cables. While the wire circuits 32 are formed substantially as in the previously described embodiments, the wire circuit 31 forms a branch 31 'in the form of an additional circuit along a vertical side edge of the windshield. This branch 31 'of the heating circuits also serves to heat the windshield region, which is adjacent to the supports A of the vehicle's working body on the driver's side. This has the advantage that the snow swept on this side by the windshield wiper melts and does not accumulate a form of distraction along the support A as the vehicle is being driven. The windshield 40 shown in Figure 5 represents a mode in which the regions adjacent to the supports A on both sides are also heated. Also in this case, the lower region where the wipers of the windshield are placed at rest, is heated by the wire circuits 41, 42 which extend substantially horizontally. The wire circuits 41 in this case form branches 41 'and 41"in the form of a circuit, which extend parallel to the lateral edges along each of the two lateral edges, the ends 43, 44 of the wire circuits. they are normally welded to the collection conductors 45, 46, which in turn are connected to electrical connection conductors 47, 48 in the form of flat cables.

Claims (10)

1. A windshield made of laminated glass, which is provided, in the region where the windshield wipers are placed at rest, with electrical heating resistive wires, mounted in parallel and embedded in the thermoplastic intermediate layer, whose wires are in contact with films of a thin sheet of metal acting as collection conductors, also embedded in the intermediate layer and connected to the conductors to supply current, characterized in that the two thin sheet metal films act as collection conductors which are arranged very close to each other and because the resistive heating wires extend in the form of circuits between those collection conductors.

2. The windscreen according to claim 1, characterized in that the heating resistive wires are arranged in the form of circuits embedded within one another, these circuits being axially symmetrical with respect to the midline (MM) of the windshield, the ends of the wire circuits are flexed downwards and the thin sheet metal films acting as collection conductors are arranged in the middle part of the lower edge of the windshield.

3. The windshield according to claim 1, characterized in that the resistive heating wires are arranged in the form of U-shaped circuits fitted to each other and oriented horizontally, including end regions which extend in a straight line and are in contact with the collection conductors arranged close to each other along a side edge of the windshield.

4. The windshield according to claim 1, characterized in that the heating resistive wires are arranged in the form of horizontally oriented circuits and fitted together, the ends of the wire circuits are flexed downward in the region of a lower corner of the windshield and the thin sheet metal films that act as collection conductors are arranged in this corner region at the lower edge of the windshield.

5. The windscreen according to any of claims 1 to 4, characterized in that one or more of the wire circuits form a branch in the form of an additional circuit, which extends along a side edge of the windshield.

6. The windscreen according to any of claims 1 to 4, characterized in that one or more of the wire circuits form two circuit-shaped branches, which are arranged along the two lateral edges of the windshield.

7. The windshield according to any of claims 1 to 6, characterized in that the heating resistive wires are arranged in a corrugated form in the thermoplastic intermediate layer.

8. The windscreen according to any of claims 1 to 6, characterized in that the heating resistive wires are arranged in such a way that they are in a straight line, that is to say that they are not corrugated in the thermoplastic intermediate layer.

9. The windscreen according to any of claims 1 to 7, characterized in that the heating resistive wires consist of a copper wire, particularly copper wire covered with a black lacquer.

10. The windscreen according to any of claims 1 to 9, characterized in that the electrical connection conductors, leaving the laminated glass pane are provided in the form of flat cables.