Steering wheel unit

Abstract

Steering wheel unit with a steering wheel body (10), a gasbag housing (30) received in the hub area of ​​the steering wheel body, in which a gasbag (38) is received, first positioning units (40) acting between steering wheel body (10) and gas bag housing (30), which position the gas bag housing (30) axially on the steering wheel body (10), and second positioning units acting between steering wheel body (10) and gas bag housing (30), which position the gas bag housing (30) in the radial plane on the steering wheel body (40), wherein at least one second positioning unit has at least one axially extending positioning element (52, 62) with at least one contact surface (56, 66a, 66b) whose surface normal or surface normals are perpendicular to the axial direction, and a counter-contact surface (58, 68a, 68b) for the contact surface (56, 66a, 66b), where the positioning element (52, 62) comprises at least one positioning section (54, 64a, 64b) which is elastically deformable perpendicular to the axial direction and has a contact surface (56, 66a, 66b), and a rigid movement limiting section (57, 67) which is arranged on a side of the positioning section (54, 64a, 64b) facing away from the contact surface (56, 66a, 66b) and spaced apart from it by means of a slot, so that the movement limiting section (57, 67) is not in contact with either the positioning section (54, 64a, 64b) or with a counter-contact surface.

Description

[0001] The invention relates to a steering wheel unit according to the preamble of claim 1.

[0002] Almost every steering wheel unit in a motor vehicle has an airbag module. Typically, the steering wheel unit consists of a steering wheel body and an airbag module housed in the hub area of ​​this steering wheel body. The airbag housing of this airbag module is covered by a roof, which forms part of the steering wheel surface. Typically, the surface of the roof also serves as an actuation surface for the vehicle horn, so that when a force exceeding a predetermined value is exerted on the roof, the horn is activated.There are basically two concepts: the so-called "floating cover" concept, in which the housing is rigidly connected to the steering wheel body and the roof can be pressed down relative to the housing and the steering wheel body, and the so-called "floating module" concept, in which the roof is rigidly connected to the housing and the roof and housing are pressed down against the steering wheel body, with the housing and steering wheel body being connected to each other by horn springs. Recently, motionless or almost motionless systems have also become known which do not have horn springs, but in which the housing is not moved at all or almost not at all against the steering wheel body when the corresponding force is transmitted. In this case, the classic horn contacts are replaced by piezo elements, for example.

[0003] The aforementioned floating module steering wheel units must be provided with positioning units that position the gas bag housing both in the axial direction and in the radial plane on the steering wheel body. For example, it is known to provide separate first positioning units, which serve for axial positioning, and second positioning units, which serve for positioning in the radial plane. In the aforementioned generic document, three second positioning units are provided, each of these second positioning units being constructed as follows: Extending in the axial direction from the base of the gas bag housing, a pin serves as a positioning element, the outer surface of which serves as a contact surface. This pin extends into an opening through a component of the steering wheel body, the inner surface of which forms the counter-contact surface for the contact surface.Due to manufacturing tolerances, it is practically unavoidable to provide a certain amount of play between the contact surfaces and the counter contact surfaces, which in turn can lead to noise and wear on the contact surfaces and the counter contact surfaces.

[0004] To prevent such play, DE 10 2008 028 126 A1 proposes a receiving element for the positioning element serving as the contact surface. This receiving element has two interconnected legs, resulting in a U-shaped structure. The first leg has the counter-contact surface, and an elastically deflectable arm extends from the opposite second leg, pressing the positioning element onto the counter-contact surface. One end of the arm is connected to the second leg, while the other end of the arm is spaced apart from the second leg. A very similar concept is also known from WO 2010 / 078896 A1.

[0005] WO 2013 / 080753 A1 shows two positioning elements spaced apart from each other, which are positioned between two oppositely positioned counter-contact surfaces.

[0006] Based on this, the present invention aims to improve a steering wheel unit in such a way that the functional reliability of the steering wheel unit is ensured even when the gas generator is ignited.

[0007] This object is achieved by a steering wheel unit having the features of claim 1.

[0008] According to the invention, the positioning element of at least one second positioning unit has at least two sections, namely a positioning section which is elastically deformable perpendicular to the axial direction and has the contact surface, and a rigid movement-limiting section which is arranged on a side of the positioning section facing away from the contact surface and spaced therefrom by a slot. The elastically deformable positioning section achieves tolerance compensation and, if appropriate, also freedom from play. Without additional measures, however, the deformability of the positioning section could lead to the gas bag housing being deflected so far in the radial plane relative to the steering wheel body upon expansion of the gas bag and, in particular, upon impact, that the first positioning units become unlatched.To prevent this, the rigid movement limiting section is provided, which only allows movement of the airbag housing in the radial plane to the extent that it does not cause one of the first positioning units to disengage. This, in particular, eliminates the need for additional safety measures.

[0009] In principle, the positioning element of a second positioning unit can extend either from the gas bag housing or from the steering wheel body, wherein it is preferable for the positioning element to extend from the bottom of the gas bag housing, whereby it is particularly possible to form it in one piece with the housing bottom, in particular if the housing is wholly or partly a plastic element produced by injection molding.

[0010] As is generally known from the prior art, it is further preferable for the contact surface of the positioning section to be convex. In this case, the positioning section preferably has the shape of a half hollow cylinder.

[0011] In order to ensure that the positioning section is not only elastically deformable overall, but also that its width can be elastically varied, the positioning section preferably has a slot extending in the axial direction.

[0012] In a first type, the positioning element has precisely one positioning section with a convex contact surface, and the counter-contact surface has a complementary concave main section against which the contact surface rests. The contact surface is preferably a section of a cylinder jacket. To further improve deformation limitation, a secondary section adjoins each end of the main section, with a portion of the movement-limiting section arranged between the two secondary sections but spaced apart from them.

[0013] In a second type, the positioning element has two positioning sections between which the movement limiting section is arranged.

[0014] In a particularly preferred embodiment, the steering wheel unit comprises two second positioning units of the first type and one second positioning unit of the second type. This allows for very precise positioning while simultaneously avoiding static overdetermination.

[0015] The steering wheel unit can be designed as a classic "floating module steering wheel unit," in which the gas bag housing can be pressed against the steering wheel body against the force of spring elements, so that the first positioning units position the gas bag housing axially on the steering wheel body only when it is not pressed down. However, the invention can also be used in steering wheel units in which no noticeable movement occurs between the gas bag housing and the steering wheel body when the driver presses on the roof of the gas bag housing to activate the horn.

[0016] The invention will now be explained in more detail using an exemplary embodiment with reference to the figures. Fig. 1 a schematic plan view of the hub area of ​​a steering wheel unit, Fig. 2 a section along the plane AA in Fig. 1, Fig. 3 a section along the plane BB Fig. 1, Fig. 4 the housing of the gas bag module of the steering wheel unit of the Fig. 1 to 3 in a detailed perspective view, Fig. 5 the housing Fig. 4 with inserted gas generator in a plan view from below, Fig. 6 that in Fig. 5 Shown in a perspective view, Fig. 7 a holding plate which is part of the steering wheel body, Fig. 8 a second positioning unit of a first type in one of the Fig. 7 corresponding representation and Fig. 9 a second positioning unit of a second type in one of the Fig. 8 corresponding representation.

[0017] A single embodiment is described. Fig. 1 to 3 are highly schematized, while the Fig. 4 to 9 are detailed.

[0018] The Fig. 1 and Fig. 2 shows part of a steering wheel unit that has a so-called "floating module" for activating the horn. This means that the steering wheel unit essentially consists of a steering wheel body 10 and a gas bag module that can be depressed in a recess in the hub area of ​​the steering wheel body 10 against the force of horn springs 20. The gas bag module has a gas bag housing 30, a roof 31 rigidly connected to the gas bag housing 30, a gas bag 36 folded into the gas bag housing, and a gas generator 36 attached to the gas bag housing.

[0019] The gas bag housing 30 is connected to a part of the steering wheel body 10, namely to a retaining plate 14, by means of the horn springs 20. This retaining plate can be made of metal, in particular, although it may be advantageous to overmold this metal retaining plate 14 with plastic, at least in sections. Several pairs of horn contacts 23, 33 are provided, with two horn contacts of each pair facing each other in the usual manner.

[0020] In order to hold and position the gas bag housing 30 on the steering wheel body 10, several positioning units are provided. A total of three first positioning units 40 are provided, which serve for axial positioning, and three second positioning units are also provided, which serve for positioning the gas bag housing 30 in the radial plane. A first and a second positioning unit are adjacent to each other, and the positions of the pairs of positioning units are in Fig. 1 with the reference symbols P, P' and P''.

[0021] All first positioning units 40 are constructed identically to one another and are described below in particular with reference to the Fig. 3, Fig. 4, Fig. 6 and Fig. 7 described in more detail.

[0022] There are two types of second positioning units, namely the first type second positioning units located at positions P and P', and a second type second positioning unit located at position P''.

[0023] All positioning units have a housing-side part and a steering wheel body-side part. The steering wheel body-side parts are each sections of the holding plate 14, so that with respect to the Fig. 7 will be discussed first. Fig. Figure 7 shows the retaining plate 14 in a top view, i.e., from the perspective of the gas bag housing 30. The retaining plate 14 has five openings 16a to 14e, with the first three openings 16a to 16c belonging to the positioning units. Each of the first three openings 16a to 16c is part of both a first positioning unit and a second positioning unit.

[0024] In each of the first three openings 16a to 16c, a projection 47 projects, the downward-facing surface 48 of which (see Fig. 3) serves as a holding surface for a first positioning element on the gas bag housing side. Furthermore, the first two openings 16a and b each have a counter-contact surface with a concave, namely semicircular, main section 58a and secondary sections 58b and 58c extending from this main section 58a (see also Fig. 8). The third opening 16c has two opposing counter-contact surfaces 68a and 68b.

[0025] The fourth opening 16d serves for the passage of an earth connection 34 (see Fig. 4), the fifth opening 16a provides access to the ignition socket of the gas generator 36.

[0026] How to use the Fig. 3, Fig. 4 and Fig. 6, the housing-side elements of the first positioning units 40 each consist of a wire bracket 42 and a plastic element 44 snapped onto this bracket 42, the upwardly facing surface 46 of which engages the downwardly facing surface 48 of the associated projection 47. Assembly takes place with elastic deformation of the brackets 42. Since no further retaining units are provided, it is important that the first positioning units 40 do not unlatch upon ignition of the gas generator 36 and expansion of the gas bag 38. To ensure this and to still achieve tolerance compensation, the second positioning units, and in particular their housing-side positioning elements 52 and 62, are constructed as follows: The second positioning units of the first type will be described first. In these second positioning units, the housing-side positioning element 52, which interacts with a respective counter-contact surface, consists of two sections, namely a positioning section 54 and a movement-limiting section 57. Both sections extend axially from the bottom of the gas bag housing 30 and can, in particular, be formed integrally therewith, especially if the gas bag housing is entirely or partially a plastic injection-molded part.

[0027] How to use the Fig. 5 and Fig. As can be seen from Figure 8, the positioning sections 54 are each designed in the form of a half hollow cylinder, which is divided into two mirror-symmetrical parts by means of a slot 55 running in the axial direction. This results in a certain elastic mobility of the two parts of the half hollow cylinder both toward each other and in the direction of the movement-limiting section 57.

[0028] The outer side (i.e. the lateral surface) of the positioning section 44 forms the contact surface 56, which follows the shape of the concave main section 58a of the counter contact surface 58.

[0029] The movement-limiting section 57 is spaced from the positioning section 54, whereby the distance can be, for example, 0.8 mm. A front protrusion 57a ​​of this movement-limiting section 57 extends essentially to the center axis of the hollow cylinder of the positioning section 54. The movement-limiting section 57 is block-shaped and thus rigid. The secondary sections 58b and 58c of the counter-contact surface 58 extend beyond the front edge of the movement-limiting section 57.

[0030] Due to the design of the positioning section 54, as already mentioned, it has a certain elasticity, so that tolerance compensation can take place, which also enables essentially play-free guidance in the main section 58a of the counter-contact surface 58. However, the maximum deformation of the positioning section 54 is limited by the movement limiting section 57, since in the event of excessive deflection, either the positioning section 54 or one of the secondary sections 58b, 58c comes into contact with the movement limiting section 57. This has the effect that even upon ignition of the gas generator and subsequent expansion of the airbag with the occurrence of a catch impact, during which very large forces can occur, the movement of the airbag housing 30 in the radial plane is limited, so that unintentional unlocking of the first positioning units is reliably prevented.

[0031] The second positioning unit of the second type (see in particular Fig. 9) is constructed similarly to the second positioning units of the first type just described. The difference here is that two opposing positioning sections 64a, 64b are provided, between which the movement-limiting section 67 is located. Here, too, the positioning sections 64a, 64b are designed as slotted half hollow cylinders. The counter-contact surfaces 68a, 68b are essentially flat, so that further tolerance compensation can be achieved in the direction of the arrow. Here, too, the movement-limiting section 67 limits the possible deformation of the positioning sections. List of reference symbols 10 steering wheel bodies 12 Recess in the hub area 14 Holding plate 16a-e breakthrough 20 horn spring 23 steering wheel side horn contact 30 gas bag housing 31 roof 32 side wall 33 housing-side horn contact 34 Earth connection 36 gas generator 38 gas bag 40 first positioning unit 42 housing-side bracket 44 snap-on plastic element 46 upward facing surface 47 lead 48 downward-facing surface of the projection 52 housing-side positioning element 54 Positioning section 55 slot 56 contact surface 57 Movement restriction section 57a anterior protrusion 58a Main Section 58b, 58c Subsection 62 housing-side positioning element 64a, 64b Positioning section 65a, 56b slot 66a, 66b contact surface 67 Movement restriction section 68a, 68b Counter contact surface 70 Positioning arm P, P', P'' Range of positioning units

Claims

[1] Steering wheel unit with a steering wheel body (10), a gas bag housing (30) accommodated in the hub area of ​​the steering wheel body, in which a gas bag (38) is accommodated, first positioning units (40) acting between the steering wheel body (10) and the gas bag housing (30), which position the gas bag housing (30) in the axial direction on the steering wheel body (10), and second positioning units acting between the steering wheel body (10) and the gas bag housing (30), which position the gas bag housing (30) in the radial plane on the steering wheel body (40), wherein at least one second positioning unit has at least one positioning element (52, 62) extending in the axial direction with at least one contact surface (56, 66a, 66b), the surface normal or surface normals of which are perpendicular to the axial direction, and a counter contact surface (58, 68a, 68b) for the contact surface (56, 66a, 66b), where the positioning element (52, 62) has at least one positioning section (54, 64a, 64b) which is elastically deformable perpendicular to the axial direction and has the contact surface (56, 66a, 66b), and a rigid movement-limiting section (57, 67) which is arranged on a side of the positioning section (54, 64a, 64b) facing away from the contact surface (56, 66a, 66b) and spaced therefrom by means of a slot, so that the movement-limiting section (57, 67) is in contact neither with the positioning section (54, 64a, 64b) nor with a counter-contact surface. [2] Steering wheel unit according to claim 1, characterized by that the positioning element (52, 62) extends from the bottom of the gas bag housing (30). [3] Steering wheel unit according to claim 2, characterized by that the positioning element (52, 62) is formed integrally with the housing base. [4] Steering wheel unit according to one of the preceding claims, characterized bythat the positioning section (54, 64a, 64b) has substantially the shape of a half hollow cylinder. [5] Steering wheel unit according to one of the preceding claims, characterized by that the positioning section (54, 64a, 64b) has a slot (55, 65) extending in the axial direction. [6] Steering wheel unit according to one of the preceding claims, characterized by that the positioning element (52) has exactly one positioning section (54) and that the counter-contact surface (58) has a preferably concave main section (58a) against which the contact surface (56) rests. [7] Steering wheel unit according to claim 6, characterized by that a secondary section (58b, 58c) adjoins each end of the main section (58a) and that a part of the movement limiting section (57) is positioned between the two secondary sections (58b, 58c) but is spaced apart from them. [8] Steering wheel unit according to one of claims 1 to 5, characterized by that the positioning element (62) has two positioning sections (64a, 64b) and that the movement limiting section (67) is arranged between these two positioning sections (64a, 64b). [9] Steering wheel unit according to one of the preceding claims, which has three second positioning units, two of these second positioning units being according to one of claims 6 or 7 and one of these second positioning units being designed according to claim 8. [10] Steering wheel unit according to one of the preceding claims, characterized by that at least one spring element (20) is provided, against the force of which the gas bag housing (30) can be pressed down in the direction of the steering wheel body (10), so that the first positioning units (40) position the gas bag housing (30) in its non-pressed-down state in the axial direction on the steering wheel body (10).

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