Electrically heated webbing and methods for manufacturing an electrically heated webbing

Abstract

The present invention relates to a method for manufacturing an electrically heated webbing and an electrically heated webbing, which comprises at least a webbing fabric (1) extending in the longitudinal direction (2), a first heating wire (3) embedded in the webbing fabric (1), wherein the first heating wire (3) extends in the longitudinal direction (2) of the webbing fabric (1), a second heating wire (4) embedded in the webbing fabric (1), wherein the second heating wire (4) extends in the longitudinal direction (2) of the webbing fabric (1) parallel to the first heating wire (4), and an electrically conductive connecting element (7), wherein the connecting element (7) electrically connects the first heating wire (3) and the second heating wire (4).

Description

[0001] The present invention relates to an electrically heatable belt webbing and in particular to a belt webbing retractor with an electrically heatable belt webbing that can be wound onto a belt shaft and to a method for producing an electrically heatable belt webbing.

[0002] To reduce the energy consumption of a motor vehicle by keeping the temperature in the vehicle interior relatively low at low outside temperatures, it is known to use heated belt straps that rest on the body of the occupant when the seat belt is fastened, thus directly warming the occupant. Since the belt straps are subjected to constant stress when fastening and removing the seat belt, particularly in the area of ​​the belt guide, the heating wires must be arranged flexibly. Furthermore, the belt straps must also be able to be wound onto a belt reel with the heating wires.

[0003] For example, double-layered belts are known for this purpose, in which the heating wires run longitudinally in a space between the layers of the belt. Electrically heatable belts are also known in which the heating wires are woven into the webbing fabric, particularly as warp threads, during the production of the webbing fabric. The present invention particularly relates to such belts in which at least two heating wires are woven into the webbing fabric during the production process.

[0004] To be used as heating wires, the heating wires must be connected to the terminals of a power source. This connection of each heating wire to the terminals of a power source usually takes place outside the webbing in the area of ​​the end fitting. It is known that the two ends of exactly one heating wire are each connected directly to one terminal of the power source.

[0005] The object of the present invention is therefore to solve the problems described in the prior art and in particular to provide a belt, a belt retractor and a method with which the effort of contacting heating wires running parallel in a belt can be reduced.

[0006] A solution to this problem is provided by the webbing and the method according to the independent claims, with further solutions and advantageous developments being specified in the preceding and subsequent descriptions as well as in the subclaims. Individual features of the advantageous developments can be combined with one another in a technically expedient manner. Features disclosed with reference to the webbing are applicable to the method and vice versa.

[0007] The object is achieved in particular by an electrically heatable belt webbing which comprises at least one belt webbing fabric extending in the longitudinal direction, a first heating wire embedded in the belt webbing fabric and a second heating wire embedded in the belt webbing fabric as well as an electrically conductive connecting element, wherein the first heating wire and the second heating wire each run in the longitudinal direction of the belt webbing and parallel to one another and the electrically conductive connecting element electrically connects the first heating wire and the second heating wire, so that the connecting element is arranged directly on the belt webbing and the heating wires do not have to be led out beyond the belt webbing with both ends.

[0008] The object is also achieved by a method for producing an electrically heatable belt strap, in particular for producing an electrically heatable belt strap according to the invention, which comprises at least the following steps: - introducing a first heating wire into a webbing fabric so that the first heating wire runs in the longitudinal direction of the webbing fabric, wherein the first heating wire is preferably introduced as a warp thread during the manufacture of the webbing fabric, - introducing a second heating wire into the webbing fabric so that the second heating wire runs parallel to the first heating wire in the longitudinal direction of the webbing fabric, wherein the second heating wire is preferably also introduced as a warp thread during the manufacture of the webbing fabric, - Producing an electrically conductive connection between the first heating wire and the second heating wire with an electrically conductive connecting element, wherein the electrically conductive connecting element is arranged on the webbing fabric.

[0009] It is particularly proposed that the heating wires connected to the connecting element are led out of the webbing fabric in the region of the connecting element, so that the connecting element can be applied to the webbing fabric from an outside in order to contact the two heating wires with each other.

[0010] The invention also encompasses the formation of additional heating wires in the webbing fabric, which run in the longitudinal direction of the webbing fabric. Additional connecting elements can then be provided, each of which electrically connects two heating wires to each other.

[0011] In other words, the basic concept of the invention provides that two parallel heating wires are electrically connected to each other by means of an externally applied connecting element. This allows the heating wires to be connected, in particular, in series. Thus, a heating wire, for example, at one end of the webbing fabric, only needs to be connected to one pole of a power source. It is therefore not necessary for each heating wire to be individually connected to both poles of a power source.

[0012] The connecting element is preferably formed as a metal foil, for example, as copper foil or aluminum foil. The electrically conductive metal foil thus has a width and length that are each significantly (at least 10, preferably at least 20 times) greater than the thickness of the foil. The ohmic resistance of the connection between the two heating wires can also be adjusted by adjusting the size of the metal foil.

[0013] In principle, it would be conceivable that such an electrically conductive metal foil could be attached to the webbing fabric by means of mechanical fastening elements.

[0014] However, it is preferred that the electrically conductive metal foil be attached to the webbing fabric using a flat adhesive element in such a way that the heating wires are electrically connected to one another. For example, the electrically conductive metal foil could be attached to the webbing fabric using an adhesive, whereby the adhesive can be omitted in the area of ​​the contact points between the electrically conductive metal foil and the heating wires. It can also be provided that the electrically conductive metal foil is attached to the webbing fabric using double-sided adhesive tape.

[0015] However, it is preferred that a flat adhesive element, such as an adhesive tape or an adhesive film, covers the electrically conductive connecting element and extends beyond the connecting element on all sides. This also prevents the connecting element from being accidentally contacted or eroded.

[0016] In this case, the flat adhesive element protrudes over the connecting element, particularly in the direction of length and width, with the overhang being at least the length or width of the connecting element.

[0017] To produce the electrically conductive connection, it can be provided that the one or, in particular, several connecting element(s) is / are attached to the flat adhesive element (adhesive tape, adhesive film) and that the connecting element(s) is / are fastened together with the flat adhesive element to the webbing fabric.

[0018] Preferably, the (flat) adhesive element is a heat-activated adhesive element, which is applied at a temperature between 60°C and 120°C, preferably between 70°C and 110°C, and at a pressure between 1.5 bar and 6 bar, preferably between 2 bar and 5 bar. Such a heat-activated adhesive element ensures particularly secure attachment of the connecting element to the webbing fabric.

[0019] In this context, it is assumed that at least the adhesive of the heat-activatable adhesive element penetrates into the spaces formed by the webbing fabric, thereby achieving particularly good attachment of the adhesive element to the webbing fabric. In addition, by applying the temperature and pressure, the connecting element, which is in particular designed as a metal foil, can adapt to the surface structure of the webbing and preferably also penetrate into the spaces in the webbing fabric, whereby the connecting element is additionally fixed to the webbing fabric and whereby a particularly secure electrically conductive connection is created between the connecting element and the respective heating wire. In addition, the application of the temperature and pressure ensures that the adhesive element forms a materially bond with the webbing fabric even in the immediate vicinity of the connecting element.

[0020] In a further embodiment, the connecting element can be integrated into a circuit board, which can be arranged on the webbing fabric. In this case, it is particularly important to ensure that the heating wires can be routed from the webbing fabric to the circuit board and, if necessary, via the circuit board to contact the connecting element on the circuit board. When using a circuit board, the heating wires can be soldered to the connecting element on the circuit board. The circuit board can be attached to the webbing fabric, for example, using one of the adhesive elements described above.

[0021] Alternatively or additionally, the circuit board can be covered by a cover that is, for example, mechanically connected to the webbing fabric outside the circuit board. The cover can be arranged and designed in such a way that mechanical (tensile) stresses on the connection point between the heating wire and the conductor element are avoided, for example, by also connecting wires to the cover or by the cover locally fixing the heating wires relative to the webbing fabric.

[0022] The use of a printed circuit board also has the advantage that electronic components can be arranged on the circuit board and / or on the webbing fabric. For example, a temperature sensor can be arranged on the circuit board and / or the electrical connections of a temperature sensor can be connected to the circuit board, in which case the temperature sensor can be mounted on the webbing fabric away from the circuit board.

[0023] In a further embodiment, the electrically conductive connecting element can be designed as an electrically conductive thread sewn into the webbing fabric. Such an electrically conductive thread is thus provided in addition to the warp and weft threads of the webbing fabric and connects the two heating wires to each other in an electrically conductive manner. By sewing in an electrically conductive thread, it is securely connected to the webbing fabric, so that no further means for fixing the connecting element are required. Nevertheless, the electrically conductive thread can also be covered by an adhesive element.

[0024] While it is in principle possible for the sewn-in electrically conductive thread to be aligned orthogonally to the parallel heating wires, a preferred embodiment provides for the sewn-in electrically conductive thread to run at least partially in the direction of the belt webbing. The thread therefore has an extension component that is not orthogonal to the heating wire. In particular, it is provided that the thread runs at an acute angle, preferably at an angle of less than 45° or less than 30°, to the heating wire in the area of ​​contact with the heating wire. In this way, an electrically conductive connection between the heating wire and the electrically conductive thread can be ensured particularly efficiently.

[0025] If the webbing is secured to a belt shaft of a belt retractor by one end having a webbing pin, and the webbing can be wound onto the webbing shaft, one embodiment of the invention proposes that the connecting element be arranged in the region of the webbing pin. Arranging the connecting element in the region of the webbing pin and thus at one end of the webbing ensures that the electrically conductive connections between the connecting element and the heating wires are subjected to only relatively low mechanical stress during use.

[0026] In this context, the webbing pin may be provided with a recess / recess / notch for the connecting element, so that the connecting element is arranged in the recess. This ensures that the mechanical stress on the connection points between the connecting element and the heating wires is further reduced.

[0027] It can also be provided that the connecting element is arranged on the webbing pin. For example, the connecting element can be designed as a film that is attached to the webbing pin and, for example, wound onto the webbing pin. Alternatively, the connecting element can be designed as a sleeve pushed onto the webbing pin. If the connecting element is then additionally fixed to the webbing fabric, for example, using an adhesive, the mechanical stress on the connections between the connecting element and the heating wires is also reduced in this case.

[0028] If the previously free end of the belt webbing is laid on itself to form a belt fold around the belt pin and is fastened to itself, for example by means of a seam, it is provided in particular that the connecting points between the heating wires and the connecting element are arranged in the hollow space formed by the belt fold, to which the shape is also aligned.

[0029] The invention and the technical environment are explained below by way of example with reference to the figures. They show schematically Fig. 1: a top view of a webbing, Fig. 2: a top view of two connecting elements on an adhesive element, Fig. 3: the connecting elements attached to the webbing with the adhesive element, Fig. 4: another embodiment of a belt strap, Fig. 5: yet another embodiment of a belt strap, Fig. 6: an embodiment of a belt strap with connecting elements in the area of ​​a belt strap pin, Fig. 7: another embodiment of a belt strap with connecting points in the area of ​​a belt strap pin, Fig. 8: an embodiment of a belt strap with connecting elements formed on a circuit board and Fig. 9: an embodiment of a webbing with a connecting element made of a sewn-in thread.

[0030] Fig. 1 shows a section of a webbing. The webbing comprises a webbing fabric 1, into which a first heating wire 3, a second heating wire 4, a third heating wire 5, and a fourth heating wire 6 are woven as warp threads in the longitudinal direction 2 of the webbing. The heating wires are, as shown in Fig. 1, led outwards from the webbing fabric 1 for mutual contact.

[0031] In Fig. 2 shows an adhesive element 8 designed as a heat-activatable adhesive tape, on which two electrically conductive metal foils are arranged as connecting elements 7.

[0032] The adhesive element 8 and the two connecting elements 7 can be applied to the webbing fabric as a unit, so that the connecting elements 7 each electrically connect two heating wires 2 and 4 or 5 and 6 to one another. The unit is applied to the webbing fabric 1 at a temperature between 70 °C and 110 °C and at a pressure between 2 bar and 5 bar. In this process, at least part of the adhesive of the adhesive element 8 penetrates into the spaces between the webbing fabric 1, with the connecting elements designed as metal foil and the foil of the adhesive element 8 adapting to the surface structure of the webbing fabric 1, whereby a particularly secure connection to the webbing fabric 1 and particularly secure contacting of the heating wires 3, 4, 5, 6 is achieved.

[0033] In Fig. 3 shows the belt strap with the adhesive element 8 attached to it and the connecting elements 7.

[0034] In Fig. 4, the webbing fabric 1 and the unit consisting of adhesive element 8 and connecting elements 7 are shown schematically.

[0035] In Fig. Figure 5 shows another possible configuration of webbing 1 and a unit comprising an adhesive element 8 and two connecting elements 7. The connecting elements 7 are shaped such that, on the one hand, the two outer first and second heating wires 3 and 4 and, on the other hand, the two inner third and fourth heating wires 5 and 6 are each electrically connected by means of a connecting element 7.

[0036] In the Fig. 6 and Fig. 7 shows an unwound webbing 1 with a webbing pin 11. According to the embodiment of the Fig. 6, two electrically conductive connecting elements 7 are attached to the webbing pin 11, each connecting two heating wires 3, 4 and 5, 6. The connecting elements 7 can be designed, for example, as a foil or sleeve.

[0037] According to the embodiment of the Fig. 7, the webbing pin 11 has a recess 12 running along its longitudinal direction, in which the connecting elements 7 are arranged, each of which connects two heating wires 3, 4 or 5, 6 to one another. By arranging the electrical contact between the heating wires by means of the connecting elements 7 in the area of ​​the webbing pin 11, the mechanical stress at the connection point is reduced. Furthermore, the end of the webbing is wrapped around the webbing pin 11 to form a belt fold and sewn to itself, so that the connection point between the heating wires and the respective connecting element 7 is further mechanically relieved.

[0038] According to the embodiment of the Fig. 8, the connecting element 7 for the electrically conductive connection of two heating wires 3, 4 and 5, 6 is arranged on a circuit board 9, which is attached to the webbing 1. By using a circuit board 9, additional electronic components, such as a temperature sensor 10, can also be arranged on the webbing, whereby only one cable for connecting the circuit board 9 needs to be extended from the webbing.

[0039] In Fig.9 also shows four parallel heating wires 3, 4, 5, 6, which run in the longitudinal direction of the webbing fabric 1. For the electrically conductive connection of two heating wires 3, 4 or 5, 6, an electrically conductive thread is sewn into the webbing fabric 1 as a connecting element 7. The electrically conductive threads run in the area of ​​the heating wires 3, 4, 5, 6 at an acute angle to the heating wires, so that a secure electrically conductive connection is provided between the respective heating wire and the electrically conductive thread. List of reference symbols 1 webbing fabric 2 Longitudinal direction 3 first heating wire 4 second heating wire 5 third heating wire 6 fourth heating wire 7 Connecting element 8 adhesive element 9 Circuit board 10 Temperature sensor 11 webbing pin 12 Forming

Claims

[1] Electrically heated belt strap, comprising at least - a webbing fabric (1) extending in the longitudinal direction (2), - a first heating wire (3) embedded in the webbing fabric (1), the first heating wire (3) running in the longitudinal direction (2) of the webbing fabric (1), - a second heating wire (4) embedded in the webbing fabric (1), wherein the second heating wire (4) runs parallel to the first heating wire (3) in the longitudinal direction (2) of the webbing fabric (1), and - an electrically conductive connecting element (7), wherein the connecting element (7) electrically conductively connects the first heating wire (3) and the second heating wire (4). [2] Webbing according to claim 1, wherein the connecting element (7) is fixed to the webbing fabric by a flat adhesive element (8). [3] Webbing according to claim 2, wherein the connecting element (7) is fixed to the webbing fabric (1) by a heat-activatable adhesive element (8). [4] Belt strap according to claim 2 or 3, wherein the flat adhesive element (8) covers the connecting element (7). [5] Webbing fabric according to claim 3 or 4, wherein the adhesive element (8) is arranged at least partially in spaces formed by the webbing fabric (1). [6] Belt strap according to one of the preceding claims, wherein the connecting element (7) is designed as a metal foil, in particular as a copper foil. [7] Belt strap according to one of the preceding claims, wherein the connecting element (7) is integrated in a printed circuit board (9). [8] Webbing according to claim 7, wherein the circuit board (9) is covered by a cover which is connected to the webbing fabric (1). [9] Belt strap according to claim 7 or 8, wherein the circuit board (9) is connected to a temperature sensor (10). [10] Webbing according to one of the preceding claims, wherein the connecting element (7) is sewn into the webbing fabric (1) as an electrically conductive thread. [11] Webbing according to claim 10, wherein the electrically conductive thread runs at least partially in the longitudinal direction (2) of the webbing fabric (1). [12] Webbing according to one of the preceding claims, comprising a webbing pin (11), wherein the connecting element (7) is arranged in the region of the webbing pin (11). [13] Webbing according to claim 12, wherein the webbing pin (11) has a recess (12) for receiving the connecting element (7). [14] Webbing according to claim 12 or 13, wherein the connecting element (7) is attached to the webbing pin (11), for example as a film or as a sleeve. [15] Method for producing an electrically heatable belt strap, comprising at least the following steps: - introducing a first heating wire (3) into a webbing fabric (1) so that the first heating wire (3) runs in the longitudinal direction (2) of the webbing fabric (1), - introducing a second heating wire (4) into the webbing fabric (1) so that the second heating wire (4) runs parallel to the first heating wire (3) in the longitudinal direction (2) of the webbing fabric (1), - Producing an electrically conductive connection between the first heating wire (3) and the second heating wire (4) with an electrically conductive connecting element (7). [16] A method according to claim 15, comprising the following step: Applying a flat adhesive element (8) to the webbing fabric (1) which fixes the connecting element (7) to the webbing fabric (1). [17] Method according to claim 16, wherein the adhesive element (8) is a heat-activatable adhesive element. [18] Method according to claim 17, wherein the heat-activatable adhesive element (8) is applied at a temperature between 60 °C and 120 °C and at a pressure between 1.5 bar and 6 bar. [19] Method according to claim 17 or 18, wherein the adhesive element (8) penetrates at least partially into gaps formed by the webbing fabric (1) during application.

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