Steering wheel for a vehicle, vehicle and electronic assembly

Abstract

Steering wheel for a vehicle, the steering wheel comprising: - a steering wheel body with an earthing device adapted to be connected to the vehicle ground, the earthing device comprising a body-side earthing area, - at least one electronic assembly attached to the steering wheel body, the electronic assembly comprising an electronic component, a signal connection, and an assembly-side grounding region electrically connected to the body-side grounding region of the grounding device of the steering wheel body, and - at least one electrically conductive and elastic contact element extending between the assembly-side grounding region and the first body-side grounding region, wherein the electrically conductive and elastic contact element is under mechanical tension so that it transmits a force between the steering wheel body and the electronic assembly.

Description

[0001] The invention relates to a steering wheel according to claim 1, a vehicle with such a steering wheel according to claim 17 and an electronic assembly for mounting on such a steering wheel according to claim 18.

[0002] A steering wheel in a modern motor vehicle, particularly a passenger car, a truck, a bus, or the like, serves not only for steering the vehicle but also as a communication interface with switches, lighting elements, sensors, and the like. A steering wheel therefore comprises a steering wheel body and at least one electronic assembly attached to this steering wheel body. Such an electronic assembly comprises an electronic component, which is usually located in a housing. The steering wheel housing generally has a skeleton made of metal (usually magnesium), and this skeleton can be used as a grounding device or as part of a grounding device. The grounding device (particularly the skeleton) is in this case connected to the vehicle's ground.

[0003] The electronic assembly must of course communicate with the vehicle's electronics, so the electronic assembly includes at least one signal connector that can be electrically connected with a wiring harness.

[0004] Often, the electronic assembly includes an assembly-side grounding area that must be connected to the vehicle's ground. In this case, the vehicle body's grounding system includes a body-side grounding area to which the assembly-side grounding area is connected. The connection between the assembly-side grounding area and the body-side grounding area is established in this case by a ground cable, which may be part of the wiring harness.

[0005] Based on this prior art, it is an object of the invention to improve a steering wheel of the type described above, in particular the grounding of the electronic assembly.

[0006] This object is achieved by a steering wheel according to claim 1. A vehicle with such a steering wheel is defined in claim 17, and an electronic assembly suitable for mounting on a steering wheel body is defined in claim 18.

[0007] According to the invention, at least one electrically conductive and elastic contact element, usually a spring, is provided which extends between the module-side grounding region and the first body-side grounding region. This electrically conductive and elastic contact element is not initially pre-tensioned, but is placed under mechanical tension during assembly of the electronic assembly on the steering wheel body. During this assembly step, the electronic assembly is usually moved towards the steering wheel body, with the electrically conductive and elastic contact element being tensioned in such a way that reliable grounding of the electronic assembly is "automatically" created during the mechanical assembly process. This has the following advantages, among others: Firstly, a separate assembly step for grounding is avoided, so that grounding cannot be forgotten and assembly time is also saved.Second, the risk of damage to the electronic component due to static electricity discharge is reduced by ensuring that grounding is performed during mechanical assembly, which typically occurs before connecting the signal connector to the wiring harness or directly grounding via a dedicated cable. Finally, the grounding path is very short, reducing antenna effects that can cause EMC problems.

[0008] In a preferred embodiment, the conductive and elastic contact element is a lamellar spring, one end of which is permanently connected to the grounding area on the module side. This makes the assembly process even simpler and more reliable. In a less preferred embodiment, the spring is a helical spring.

[0009] As already mentioned, the steering wheel body's grounding device typically comprises a metal skeleton of the steering wheel body. To improve the conductivity of the body-side grounding area, the steering wheel's grounding device may also include a rivet or screw attached to the skeleton. This rivet or screw may be coated to improve the electrical contact between the conductive and elastic contact element and the body-side contact area.

[0010] As already mentioned, the electronic assembly typically comprises a housing in which the electronic component is located. This housing is preferably made of an insulating plastic material. Typically, it is preferred that the assembly-side grounding region be provided directly on the electronic component, so that the housing is not involved in the grounding. In this case, the housing has an opening through which the conductive and elastic contact element or the first body-side grounding region extends. The second alternative is generally preferred to ensure that the conductive and elastic contact element is not damaged before the electronic assembly is mounted on the steering wheel housing. Furthermore, space on the dashboard is saved, as no additional grounding lug needs to be attached to the dashboard.

[0011] In most cases, the electronic component comprises a printed circuit board, and in this case, the assembly-side grounding area is a metallic surface area of ​​the circuit board. Furthermore, the conductive and elastic contact element can be directly connected to this metallic surface.

[0012] In a relevant application of the invention, the electronic component may be an electronic control unit (ECU) comprising a controller, a micro-ECU, or a microprocessor. This ECU may, for example, control at least one further electrical and / or electronic assembly and / or receive signals from it. The at least one further electrical and / or electronic assembly may, for example, be a manually operated switch, a lighting device arranged on the steering wheel, or a touch or proximity sensor. It will often be preferred to provide more than one further electrical and / or electronic assembly, with all further electrical and / or electronic assemblies being controlled by the same ECU.

[0013] If the further electrical and / or electronic assembly is a touch or proximity sensor, this touch or proximity sensor can be arranged, in particular, in a rim of the steering wheel and designed in the form of a capacitor. It is known to use the capacitor of such a touch or proximity sensor as a heating element for the steering wheel. In this case, the capacitor can be supplied with electrical energy by a switch controlled by the ECU when the steering wheel is in heating mode.

[0014] If one of the other electrical and / or electronic assemblies also needs to be earthed, this earthing will often be provided via an earthing cable connected to an additional body-side earthing area of ​​the earthing device, which is remote from the body-side earthing area to which the electrically conductive and elastic contact element is connected.

[0015] The invention will now be described in more detail using a preferred embodiment with reference to the figures. The figures show: Fig. 1 a skeleton of a steering wheel body, Fig. 2 the detail D1 from Fig. 1 in a perspective view, Fig. 3 an electronic assembly intended to be mounted on the hub of the Fig. 1 and Fig. 2 skeleton shown to be mounted, Fig. 4 a subassembly of a steering wheel, which Fig. 1 shown skeleton, which in Fig. 3 and a cover covering the crown of the skeleton, Fig. 5 a sectional view along the plane AA in Fig. 4, Fig. 6 essentially the Fig. 5, but in a highly schematic representation, so that only the most essential features of the invention are shown, and Fig. 7 a variation on the one in Fig. 6 shown.

[0016] Fig. Figure 1 shows the skeleton 10 of a steering wheel body. The skeleton 10 is made of metal, typically magnesium, and is therefore both mechanically stable and electrically conductive. Because the skeleton is electrically conductive, it is also part of a grounding device for the steering wheel body, which is connected to the vehicle's ground. The connection to the vehicle's ground is not shown, as the skeleton 10 is shown in an unassembled precursor state.

[0017] The skeleton 10 of the steering wheel body comprises a hub 12, spokes 14 and a rim 16. Of particular relevance to the invention is the hub 12, which in Fig. 2 is shown in more detail in an excerpt.

[0018] In particular from Fig. 2 it can be seen that the hub 12 of the skeleton of the steering wheel body of this embodiment has projections 24 which are used for the positioning and / or mounting of an electronic assembly which will later be used in particular with regard to Fig. 3. In other embodiments, other types of positioning and / or fastening elements may also be provided.

[0019] The upper surface (that is, the surface facing the driver when the steering wheel is installed in a vehicle) comprises a raised portion 20. In the illustrated embodiment, a rivet 22 is attached to this raised portion 20. This rivet 22 is optional and serves primarily to create a surface that maintains good conductivity over a long period of time. A screw or similar could also be used instead of the rivet. According to the definitions chosen in this application, the rivet 22 (if present) represents part of the grounding device of the steering wheel body, namely part of a first body-side grounding region. As mentioned, the rivet is optional, and it would also be possible for a region of the skeleton alone to form this first body-side grounding region.

[0020] Fig. Figure 3 shows the aforementioned electronic assembly 40. This electronic assembly 40 comprises a housing 42, which is made at least partially of at least one plastic material, so that the housing forms an electrically insulating enclosure for at least one electronic component located within the housing. As will be described later, this electronic component comprises at least one printed circuit board (PCB). A signal connector 54 is provided for connecting the at least one electronic component located within the housing 42 to a wiring harness.

[0021] The housing 42 includes receptacles 44 that fit the projections 24 of the hub 12. In this embodiment, the receptacles 44 are designed as through holes, so that after positioning the electronic assembly 40 on the hub 12, it can be secured to the hub 12, for example, by means of screws that extend through the receptacles 44 into the projections, which here are designed as hollow cylinders. Alternative solutions for positioning and / or securing the electronic assembly to the steering wheel are conceivable.

[0022] An essential feature is that the housing 42, namely its housing base, has an opening 46, which in this embodiment has the shape of a round hole. Fig. 3 further shows that a spring 60—here a leaf spring 60—is located inside the housing 42 behind the opening 46. This spring 60 forms an electrically conductive and elastic contact element. As will be described in more detail later, this electrically conductive and elastic contact element extends from a module-side grounding area (in the illustrated embodiment, from the module-side grounding area of ​​a printed circuit board that forms part of the electronic component housed in the housing 42).

[0023] Fig. 4 shows a subassembly 5 of a steering wheel, which comprises the skeleton 10 of Fig. 1, the electronic assembly 40 from Fig. 3 and a cover 30 that covers the edge of the skeleton 10. This cover 30 is typically a foam material that is covered with a covering (e.g., leather or synthetic leather) in a later production step. Once the steering wheel is fully assembled, the electronics assembly 40 and, if applicable, parts of the spokes 14 can be covered by an airbag module.

[0024] The electronic component 50 arranged in the housing 42 is or comprises at least part of a control unit (ECU) (usually a complete control unit) for further electrical and / or electronic assemblies that are part of the fully assembled steering wheel; these further electrical and / or electronic assemblies are in Fig. 4 is not shown, especially because Fig. 4 only one subassembly is shown.

[0025] During assembly of the electronic assembly 40 to the hub 12, the raised portion 20, together with the rivet 22 (if present)—the body-side grounding area—enters the housing 42 through the opening 46, so that the spring 60 is pressed onto the body-side grounding area, and a ground connection is "automatically" established between the electronic component (the circuit board 50) of the electronic assembly 40 and the grounding device of the steering wheel (and thus the vehicle ground). In this state, the body-side grounding area, the spring 60, and the assembly-side grounding area are aligned with each other, and the spring is under mechanical tension, so that a permanent and stable mechanical and thus electrical connection is established between the spring and the body-side grounding area. This is, for example, Fig. 5, which also shows the printed circuit board (PCB) 50 of the electronic component and its assembly-side grounding region 52, from which the spring 60 extends. In the illustrated embodiment, the spring 60 is attached to the assembly-side grounding region so that it cannot be lost during the assembly process.

[0026] Fig. 6 shows essentially the same as Fig. 5, but in a highly schematic representation, so that only the features relevant to grounding are shown. As in Fig. 6, the spring 60 could also be a coil spring (which, however, is not preferred in most cases).

[0027] As from Fig.7, it would also be possible for the spring 60 to extend through the opening 46 instead of the body-side grounding area, but this is also not preferred in most cases because in this case there is a risk of the spring being damaged before the electronics assembly is mounted on the steering wheel body.

[0028] The embodiment shown is a preferred embodiment, but alternatives are also possible: The orientation of the electronic assembly can be varied, and it can be located in any area of ​​the steering wheel where grounding can be achieved. The electronic assembly can also be screwed, snapped, or latched in various ways, as long as grounding is effective. List of reference symbols 5 Steering wheel 10 Skeleton of the steering wheel body 12 Hub 14 spokes 16 wreath 20 raised part of the skeleton 22 rivets 24 lead 30 Cover 40 electronic assembly 42 housings 44 Mounting for projection 46 Opening in the case bottom 50 Printed circuit board of the electronic assembly 52 module-side grounding area 54 Signal connection 60 spring

Claims

[1] Steering wheel for a vehicle, the steering wheel comprising: - a steering wheel body with an earthing device adapted to be connected to the vehicle ground, the earthing device comprising a body-side earthing area, - at least one electronic assembly attached to the steering wheel body, the electronic assembly comprising an electronic component, a signal connection, and an assembly-side grounding region electrically connected to the body-side grounding region of the grounding device of the steering wheel body, and - at least one electrically conductive and elastic contact element extending between the assembly-side grounding region and the first body-side grounding region, wherein the electrically conductive and elastic contact element is under mechanical tension so that it transmits a force between the steering wheel body and the electronic assembly. [2] Steering wheel according to claim 1, wherein the electrically conductive and elastic element is a spring. [3] Steering wheel according to claim 2, wherein the spring is a coil spring or a lamellar spring. [4] Steering wheel according to one of the preceding claims, wherein the grounding device of the steering wheel body comprises a metal skeleton of the steering wheel. [5] A steering wheel according to claim 4, wherein the grounding means of the steering wheel body further comprises a rivet or a screw fixed to the skeleton, the rivet or the screw forming at least a part of the body-side grounding region. [6] Steering wheel according to one of the preceding claims, wherein the electronic assembly comprises a plastic housing in which the electronic component is arranged. [7] The steering wheel according to claim 6, wherein the electronic component comprises the assembly-side grounding region from which the conductive and elastic contact element extends, and wherein the housing comprises an opening through which the conductive and elastic contact element or the first body-side grounding region extends. [8] Steering wheel according to one of the preceding claims, wherein the electronic component comprises a printed circuit board. [9] The steering wheel according to claim 8, wherein the assembly-side grounding region is a metallic surface region of the printed circuit board. [10] Steering wheel according to one of the preceding claims, wherein the electronic component comprises an ECU. [11] Steering wheel according to claim 10, wherein the ECU controls and / or receives signals from at least one further electrical and / or electronic assembly selected from the group comprising: a manually operable switch, a lighting device arranged on the steering wheel and a touch or proximity sensor. [12] Steering wheel according to claim 11, wherein the at least one further electrical and / or electronic assembly is grounded via a ground cable. [13] A steering wheel according to claim 12, wherein the grounding cable is connected to an additional body-side grounding portion of the grounding device which is remote from the body-side grounding portion. [14] Steering wheel according to one of claims 11 to 13, wherein the steering wheel comprises at least one touch or proximity sensor which is controlled by the ECU and / or sends signals to the ECU, the touch or proximity sensor being arranged in a rim of the steering wheel. [15] Steering wheel according to claim 14, wherein the touch or proximity sensor is designed as a capacitor. [16] A steering wheel according to claim 15, wherein the capacitor serves as a heating element for the steering wheel, the capacitor being supplied with electrical energy by a switch controlled by the ECU when the steering wheel is in a heating mode. [17] Vehicle with a steering wheel, the steering wheel comprising: - a steering wheel body having a grounding device connected to the vehicle ground, the grounding device having a body-side grounding area, - at least one electronic assembly attached to the steering wheel body, the electronic assembly comprising an electronic component, a signal connection and an assembly-side grounding area electrically connected to the body-side grounding area, - at least one electrically conductive and elastic contact element extending between the grounding area of ​​the electronic assembly and the body-side grounding area. [18] An electronic assembly designed to be mounted on a steering wheel body, the assembly comprising a plastic housing and at least one electronic component located inside the housing, wherein: - the electronic component has an earthing area on the module side, and - the housing has an opening that is aligned with the grounding area on the module side. [19] The electronic assembly of claim 18, wherein the electronic component comprises a printed circuit board, and wherein the assembly-side grounding region is a metallic surface region of the printed circuit board.

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