WO2022253368A1

WO2022253368A1 - Steering wheel for a motor vehicle and method for producing a steering wheel

Info

Publication number: WO2022253368A1
Application number: PCT/DE2021/100468
Authority: WO
Inventors: Reinhard SCHILCHER
Original assignee: Schipek Gmbh
Priority date: 2021-05-31
Filing date: 2021-05-31
Publication date: 2022-12-08
Also published as: CN117355455A; DE112021007760A5

Abstract

A steering wheel for a motor vehicle, having a steering wheel body (2) with an inner steering wheel core (1) and at least one circumferential groove (4) at the periphery, which groove is formed in the steering wheel body (2) and has a groove base (4c) and groove side walls (4b) for accommodating free ends (3a, 3b) of strips of a cover (3) in a positionally secured manner, characterised in that barbs (5c) projecting into the groove (4) and pointing towards the groove base are provided in the steering wheel body (2) on the groove side walls (4b). According to the method for producing such a steering wheel using a mould (6), a circumferential projection (6a) that gives the groove (4) its shape is provided in the mould (6) to produce the at least one groove (4) in the steering wheel body (2). A required number of fastening clips (5, 8), clamped in the region of the barbs (5c) by the clamping force of said fastening clips, are attached to the projection (6a). The steering wheel core (1) is then wrapped in a suitable material and, after the steering wheel core (1) has been wrapped, the steering wheel body (2) is separated from the mould (6), wherein the fastening clips (5, 8) are pulled away from the projection (6a) and extend, by means of their spring force with the barbs (5c), through the side walls of the groove (4) into the groove (4). This reliably prevents the ends (3a, 3b) of a cover (3) from slipping out of the groove (4). (Figure 7)

Description

Steering wheel for a motor vehicle and method for manufacturing a steering wheel

description

The present invention relates to a steering wheel for a motor vehicle, with a steering wheel body with an inner steering wheel core and at least one groove running around the circumference formed in the steering wheel body and having a groove base and groove side walls for receiving free ends of strips of a sheathing in a secured position Process for manufacturing such a steering wheel.

Nowadays, steering wheels are usually manufactured using an injection molding process. For this purpose, an injection mold consisting of several parts is used, into which a steering wheel skeleton made of aluminum or steel is inserted and then a foam layer, e.g. made of polyurethane, is applied to the round steering wheel rim.

For tactile reasons, vehicle drivers prefer to cover the foam steering wheel rim with a comfortable material, such as leather, simply because of their quality feeling. The attractive visual appearance of the steering wheel also plays a major role in connection with the rest of the interior of the vehicle. Therefore, most steering wheel rims are now provided with a casing. The use of a clamping groove to secure an order sheathing has been known for over 60 years by inserting and gluing the ends of the sheathing into the clamping groove.

However, there are some problems with the permanently secure anchoring of the sheathing ends that have been introduced in the groove, so that a clamping groove has only been used with great reluctance to this day. When casting a steering wheel with a groove, this groove, like all elements manufactured using the injection molding process, must have a minimum bevel of 1 to 2 degrees, otherwise the injection mold can no longer be easily removed after the material has been shaped and parts of the steering wheel casing can be damaged by a vacuum and surface friction can be damaged. However, such a minimal bevel later reduces the hold of the sheathing ends in the groove. The materials pressed into a steering wheel groove, such as leather, can loosen over time in the groove and possibly slip out due to their softness, their different expansions in heat and cold and their material changes due to aging.

A similar problem also arises for adhesive connections, where it cannot be ruled out that they can become detached from the casing on the steering wheel over time as a result of intensive use, vibrations on the steering wheel, as well as changes in the materials due to aging and strong temperature changes.

The present invention is therefore based on the task of providing a permanently secure and age-resistant fixation of the casing ends in a groove.

According to the invention, this object is achieved by a steering wheel having the features of claim 1 and a method having the features of claim 8 . Further advantageous configurations can be found in the respective dependent subclaims. According to the invention, barbs protruding into the groove are provided in the steering wheel body on the groove side walls. One or more barbs may be provided on each side of the groove. The barbs should be shaped so narrowly and pointing inwards that they can relatively easily push through any steering wheel body material that may still be present and can also reliably prevent the ends of the casing from slipping out. The tips of the barbs should be wedge-shaped or tapered to provide a good bite into the sheath material. Other embodiments such as rounded wire ends etc. are also conceivable. The barbs can point towards the bottom of the groove or in another direction. The decisive factor is that they prevent the sheathing from slipping out of the groove.

The barbs are particularly preferably resilient in relation to the depth of penetration into the groove, so that they can retreat through the side walls of the groove when the ends of the sheath are inserted and engage in the material when the sheath is pulled out and prevent it from slipping out.

According to a particularly preferred embodiment of the invention, the Widerha ken are arranged at the end of spring arms of the groove at least partially surrounding, located in the steering wheel body mounting brackets. The mounting brackets can have different shapes, with the spring arms at least partially surrounding the side walls of the groove and with a web connecting the spring arms ver the bottom of the groove. The design of the spring arms and the web connecting the spring arms can take on various forms. In the case of a round or U-shape, the bar is omitted and the spring arms merge into one another. In an advantageous embodiment, the fastening clip has the approximate shape of an open, almost round spring clip (D-shaped configuration) with barbs at the ends. The distance between the openings between the barbs corresponds approximately to the width of the groove in all versions, with the distance between the tips of the barbs themselves being somewhat smaller than the width of the groove. The spring arms of the mounting clip are preferably bent slightly inward to allow some compression on the side walls of the groove after being sheathed in a suitable material in a mold. This pressure must Large enough to allow the barbs of the mounting clip to penetrate any wrapping material that may be present, but weak enough that the barbs only reach a little into the groove. The length of the barbs in the groove depends on the width of the groove and the desired material in it. The length of the barbs can be significantly greater in a wide groove than in a clamping groove, which must only provide space for the two ends of the inserted material. Due to its shape, the fastening clip can be easily pushed over the projection of a molding tool that later forms the groove. When pushing on, the spring arms of the mounting bracket are pushed apart a little so that they are under some tension. This can easily be done by machine or by hand as the barbs point inwards and thus simply slide over the mold boss.

In a steering wheel designed according to the invention, the casing is inserted with its free ends into the at least one groove, with the barbs pressing into the casing and preventing it from slipping out of the groove.

According to the method according to the invention, a circumferential projection is provided in a mold for producing the at least one groove in the steering wheel body, giving the shape of the groove, onto which a required number of fastening clips, held by their clamping force in the area of the barbs, is placed . The steering wheel core is then surrounded with a suitable material and, after the steering wheel core has been surrounded, the steering wheel body is separated from the mold, with the fastening clips being pulled from the front and protruding through the side walls of the groove into the groove with the barbs due to their spring force.

In detail, a steering wheel body is manufactured by applying a fastening clip with its barbs to a projection of a molding tool which will later produce a groove. By introducing a suitable foam material, such as polyurethane foam (PU foam), the mounting bracket is cast and is now within the foam that forms the steering wheel body. As far as in the following text from Injection mold and polyurethane foam (PU foam) is spoken, other embodiments are also possible, such as other foam material, non-foam plastics or synthetic resins, and their corresponding associated molds. The following text also speaks of an injection mold, although this usually always consists of several individual parts, because otherwise the part produced in the injection mold would not be accessible.

After pulling out the projection of the injection mold from the foamed steering wheel rim is the mounting bracket on the edge of Ma teriaaussparung that has left the projection of the injection mold, so the groove.

Due to its shape and flexibility and due to the lack of resistance of the injection mold projection, the fastening clip pushes its barbs a little way into the groove. When the sheath ends are now inserted into the groove, they can simply be pushed past the barbs, because the barbs are directed inwards and may also recede a little into the foam. Once insertion of the sheath ends is completed, the barbs bite into the inserted sheath material adjacent to them. If an attempt is made to pull out one or both ends of the casing, the barbs will bite even deeper into the casing material and thus prevent the ends of the casing inserted in the groove from being pulled out further.

It is therefore no longer possible for the ends of the casing to slip out, but neither is it possible to readjust the casings, which, however, is not a problem in machine production. The production machines are programmed in such a way that they always carry out the same work process with the same material in the same place, so that no readjustment is normally necessary. For easier processing, several fastening clips can be joined together to form a clip assembly. The fastening clips are connected to one another by means of one or more connecting elements, for example wire. Such a clamp assembly can now be easily applied to the projection of the injection mold. Depending on your preference, a corresponding number of individual fastening clamps and clamp assemblies can be attached at the desired points in a steering wheel body.

Preference is given to using D-shaped fastening clips, the spring arms preferably being arcuate and having a smaller spacing at the free end in the relaxed state than the thickness of the projection.

The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and/or shown alone in the figures can be used not only in the combination specified, but also in other combinations or on their own. Not all features of claim 1 have to be realized in order to carry out the invention. Individual features of the independent or subordinate claims can also be replaced by other disclosed features or combinations of features.

All of the features and/or advantages that emerge from the claims, the description or the drawing, including structural details, spatial arrangement and process steps, can be essential to the invention both on their own and in a wide variety of combinations. In the figures, the same or similar components are identified with the same or similar reference symbols.

The invention is described in more detail below using exemplary embodiments with reference to the figures. The illustrations show only part of the steering wheel rim in cross section, without connections to the steering wheel center part, i.e. without steering wheel spokes, steering wheel hub, airbag, etc. Directions of movement are indicated by arrows. It shows: FIG. 1 shows a cross section of a steering wheel rim;

FIG. 2 shows a section of an injection mold with a projection and a fastening clip;

Figure 3 shows the mounting bracket of Figure 2 pushed onto the projection of the injection mold;

FIG. 4 shows a detail of a steering wheel, the injected material for the steering wheel body also enclosing the fastening bracket from FIG. 3;

FIG. 5 shows the detail of the steering wheel from FIG. 4 when the projection is pulled out while the injection mold is being removed; FIG. 6 shows the section from FIG. 5 after the injection mold has been removed;

FIG. 7 shows the detail from FIG. 6 after the sheathing ends have been inserted into the groove;

FIG. 8 shows a section of an injection mold with a projection and an assembly of individual fastening clips which are to be pushed onto the projection;

FIG. 9 shows the clamp assembly from FIG. 8, which has been pushed onto the projection of the injection mold;

Figure 10 shows some exemplary features of the clip and groove and

FIG. 11 shows some examples of special designs and variations of the fastening clip.

Figure 1 shows a steering wheel, which has a steering wheel core 1 and a steering wheel body 2, and with a covering 3, such as leather, is wrapped, the ends of which are in a groove 4 are introduced. The invention and the following figures be hit the area shown in dashed lines.

FIG. 2 shows a fastening clamp 5 which is to be pushed onto the projection 6a forming the groove 4 in the injection mold 6. The mounting bracket 5 has the approximate shape of an open, almost round spring clip with barbs 5c hook at the ends. In this embodiment, the distance between the openings between the barbs 5c corresponds approximately to the width 4a (FIG. 10) of the groove 4, the distance between the tips of the barbs 5c itself being slightly smaller than the groove width 4a.

The side arms 5b of the mounting bracket 5 are slightly bent inwards to allow some pressure on the inner walls 4b of the groove 4 after molding. This pressure must be so great that the barbs 5c of the fastening clip 5 can penetrate through any casting material that may be present, but so weak that the barbs 5c only reach a little into the groove 4. The length of the barbs 5c in the groove 4 depends on the groove width 4a and the desired material in it. The length of the barbs can be significantly greater in a wide groove than in a clamping groove, which must only provide space for the two ends of the material introduced.

As shown in FIG. 3, the fastening clamp 5 can easily be pushed over the projection 6a of the injection mold 6, which later forms the groove 4, because of its shape. When sliding on, the arms 5b of the fastening clamp 5 are pushed apart a little, so that they are somewhat under tension. This can easily be done by machine or by hand since the barbs 5c point inwards and thus simply slide over the projection 6a.

The molding compound, for example polyurethane, is injected into the injection mold 6 and forms the steering wheel body 2. In FIG. 4, the injected material for the steering wheel body 2 encloses the fastening bracket 5 from FIG. In FIG. 5, the injection mold 6 is removed from the formed steering wheel body 2 . The projection 6a of the injection mold 6 leaves a cavity in the steering wheel body 2, which forms the groove 4.

After the injection mold 6 has been removed, the barbs of the clamp 5 in Figure 6 now protrude somewhat into the groove 4, with the groove base 4c and partially the side walls 4b being separated from the web 5a (Figure 10) and partially from the spring arms 5b (Figure 10). of the mounting bracket 5 are surrounded. By the force of bending its arms 5b, the mounting clip 5 pushes its barbs 5c a little into the empty interior of the groove 4.

Once the ends 3a and 3b of the sheath 3 of Figure 7 have been pushed into the groove 4, they are prevented from falling out of the groove 4 again by the shape of the barbs 5c.

For easier and faster handling, as shown in FIG. 8, several fastening clips 5 can be joined together to form a composite 8, e.g. In this example, the composite 8 is realized by two thin connecting wires 9 . The number and spacing of the individual elements can easily be varied if required.

FIG. 9 shows the clamp assembly 8 from FIG. 8, which has been pushed onto the projection 6a of the injection mold 6. FIG. The thin connectors 9 allow the composite 8 to flex easily and conform to the curved projection 6a of the injection mold 6 when fitted. However, other connection options and materials are also conceivable.

Preferably, the attachment of mounting clips and fittings is done by machine, but manual attachment is also possible.

The mounting bracket 5 can be built up in different shapes and variations, but preferably D-shaped wire, as shown in Figure 10 to over their spring arms 5b, which are connected via a web 5a, to be able to exert a certain pressure on the barbs 5c when they are pulled off the projection 6a of the injection mold 6, so that they then reach into the groove 4. Other embodiments and variations are also conceivable, such as O-shaped, U-shaped, round, angular or flat (see also FIG. 11). FIG. 10 shows the material with the groove 4 and groove width 4a by way of example.

The mounting bracket 5 can be produced in a wide variety of variations and combinations; some examples of this can be seen in Figure 11. Variant 5k shows a simple, circular, O-shaped fastening clip. Style 5v shows a square U-shaped clip with small springs in the material to create the pressure for the barbs into the groove. With version 5w you can see an additional spacer, so that the mounting brackets can always be attached at the same distance from the groove. The Be fastening clip 5x has a widened web 5a, which can provide increased resistance to the train of the ends 3a, 3b of the casing 3. Variant 5y shows an example of a fastening clip 5 with a plurality of barbs 5c, in order to be able to produce an even stronger connection with the sheathing material 3. In the embodiment 5z one can see additional, outwardly directed barbs which, by being anchored in the foam, can further increase the resistance to the casing ends 3a, 3b being pulled out. The fastening clip 5f is a clip made from a wide, flat material, e.g. stamped and bent steel, which, simply because of its width, offers considerable resistance to the sheath ends being pulled out. In addition, barbs protruding outwards are bent out, so that the fastening clip can resist even more against the sheath ends being pulled out.

In principle, the fastening clip 5 can be made of different types of material, preferably spring steel, but plastic, aluminum or other materials are also conceivable. The mounting bracket 5 should be re relatively hard and heat-resistant compared to the injection molding process, but still so flexible and soft that when attached to the projection 6a of the Injection mold 6 can be bent apart a little, in order to then bend back again later after pouring in and removing, and thus build up a small contact pressure in the groove 4.

The fastening clip 5 is cast, but since its barbs 5c sit exactly on the projection 6a of the injection mold 6, i.e. no foam gets between the barbs 5c and the projection 6a, the barbs 5c are already directly on the edge 4b of the groove when the injection mold 6 is pulled out 4, so that not much pressure of the fastening clip 5 in the soft foam is necessary to press the barbs 5c a little more into the groove 4. The fastening clip 5 should be slightly larger than the groove 4, preferably so much larger that a certain pressure can be built up for the barbs 5c by its bent arms 5b. On the one hand, these barbs 5c should reach far enough into the groove 4 that they can securely hold the casing ends 3a and 3b, but on the other hand not so far that they would impede the insertion of the casing ends 3a and 3b into the groove 4 .

Furthermore, the barbs 5c should be formed so narrow and pointing inwards that they can press relatively easily through any foam that may be present and can also reliably prevent the casing ends 3a and 3b from slipping out. The tips of the barbs 5c should be wedge-shaped or tapered to be able to bite well into the material of the casing ends 3a and 3b. Other configurations such as rounded wires etc. are also conceivable.

The fastening clamp 5 should be as thin and small as possible, so that when the injection mold 6 is filled, it presents only little resistance and is not displaced. The larger and more voluminous the fastening clip 5 is, the higher the possibility of undesirable air inclusions in the material of the steering wheel body 2. The structure and size of a groove 4 can be designed arbitrarily. For example, the groove 4 can be formed with different widths and depths, for example as a clamping groove, matching the thickness of the casing ends 3a and 3b, or as an insertion groove, wider than the casing ends 3a and 3b, or in a different form. A groove 4 with sloping or bulbous walls or other designs such as a depression or the like is also conceivable. The mounting bracket 5 must be adjusted according to the width and depth of the groove 4.

The orientation of the groove 4 in the steering wheel rim does not play a major role; it does not necessarily have to be straight, it could also be slanted, curved, kinked, etc.

Only one groove can be seen in the examples, but several grooves can also be used in the steering wheel rim. Likewise, two sheath ends 3a and 3b are always described in the groove 4, but it can be one and the same sheath (3a=3b). However, other additional elements can also be introduced into the groove 4 .

Claims

patent claims

1. Steering wheel for a motor vehicle, with a steering wheel body (2) with an inner steering wheel core (1) and at least one groove (4) formed in the steering wheel body (2) and running around the circumference with a groove base (4c) and groove side walls (4b ) for holding free ends in a secured position

(3a, 3b) of strips of a casing (3), characterized in that barbs (5c) projecting into the groove (4) are provided in the steering wheel body (2) on the groove side walls (4b).

2. Steering wheel according to claim 1, characterized in that the barbs (5c) are designed to be resilient in relation to the depth of penetration into the groove (4).

3. Steering wheel according to claim 1 or 2, characterized in that the Wi derhaken (5c) are pointed at the free end.

4. Steering wheel according to one of the preceding claims, characterized in that the barbs (5c) are arranged at the end of spring arms (5b) of the groove (4) at least partially surrounding the steering wheel body (2) befindli Chen fastening brackets (5).

5. Steering wheel according to claim 4, characterized in that the spring arms (5b) in the relaxed state have a smaller distance at the free end than the width of the groove (4).

6. Steering wheel according to claim 5, characterized in that the spring arms (5b) are arcuate.

7. Steering wheel according to claim 6, characterized in that the fastening supply clips (5) are D-shaped, the spring arms (5b) being connected via a web (5a).

8. Steering wheel according to one of claims 4 to 7, characterized in that the fastening clamps (5) are at least partially connected to one another to form a clamp assembly (8).

9. Steering wheel according to one of the preceding claims, characterized in that the casing (3) is inserted with its free ends in the at least one groove (4), the barbs (5c) pressing into the casing (3) and this prevent it from slipping out of the groove (4).

10. A method for producing a steering wheel according to one of the vorangegan gene claims 1 to 8, by means of a mold (6), characterized in that

- in the molding tool (6) for producing the at least one groove (4) in the steering wheel body (2), a projection (6a) defining the shape of the groove (4) is provided,

- a required number of fastening clips (5, 8) are placed on the projection (6a), held in the area of the barbs (5c) by their clamping force, - the steering wheel core (1) is then surrounded with a suitable material, and

- After surrounding the steering wheel core (1), the steering wheel body (2) is separated from the mold (6), the fastening clips (5, 8) be pulled by the projection (6a) and, due to their spring force, penetrate with the barbs (5c) through the side walls of the groove (4) into the groove (4).

11. The method according to claim 10, characterized in that D-shaped fastening clamps (5) are used, the spring arms (5b) preferably being arcuate and in the relaxed state having a smaller distance at the free end than the thickness of the projection (6a) amounts to.

12. The method according to claim 10 or 11, characterized in that the ends (3a, 3b) of the casing (3) are inserted into the groove (4).