WO2024046961A1

WO2024046961A1 - Steering wheel with an airbag module

Info

Publication number: WO2024046961A1
Application number: PCT/EP2023/073503
Authority: WO
Inventors: Remi Baillivet; Thierry Jacqmarcq
Original assignee: Autoliv Development Ab
Priority date: 2022-08-31
Filing date: 2023-08-28
Publication date: 2024-03-07
Also published as: DE102022122055A1

Abstract

A steering wheel comprising an airbag module (10) and a steering wheel body is described. The airbag module shows a housing element comprising a housing section (31) and a first positioning feature extending from the housing section (31). This first positioning feature is adapted for co-operating with a second positioning feature of the steering wheel body. This first positioning feature has two lateral legs (46) and a cross-piece (44) connecting the two lateral legs (46). In order to ease the mounting process of the airbag module to the steering wheel body, each of the lateral legs (46) of the first positioning 0 feature has a first thickness in its module-side end portion, preferably at the junction with the housing section (31), and a second thickness in its cross- piece-side end portion, preferably at the level of the cross-piece (44), wherein the first thickness is smaller than the second thickness.

Description

Steering wheel with an airbag module

The invention relates to a steering wheel of a vehicle according to the preamble of claim 1 , and to an airbag module adapted for being a part of such a steering wheel according to the preamble of claim 14.

Such a steering wheel comprises a steering wheel body and an airbag module being mounted to this steering wheel body, especially in such a way that the airbag module can be pressed down towards the steering wheel body in order to activate the horn of the vehicle (so-called “floating module concept”).

A generic steering wheel is known for example from CN 212604810 A. The airbag module of this steering wheel comprises a housing element with a housing section, an inflator attached to the housing section of the housing element, a cover attached to the housing section via snap-in features, and an airbag cushion being accommodated in an accommodation unit being defined by the housing section and the cover. The housing element has a first mounting feature, a second mounting feature and a resiliently flexible, U-shaped first positioning feature. The mounting features and the position feature all extend from the housing section and are parts of the housing element. The first positioning feature has two lateral legs and a cross-piece connecting the two lateral legs. The steering wheel body has a hub area for receiving the airbag module and comprises a third mounting feature co-operating with the first mounting feature, a fourth mounting feature co-operating with the second mounting feature and a second positioning feature having a lower contact surface co-operating with the cross-piece of the first positioning feature. This means that in the state in which the airbag module is not pressed down, the cross-piece of the first positioning feature and the lower contact surface of the second positioning feature contact one another such that the axial position of the first positioning feature relative to the second positioning feature is defined. During the mounting process of the airbag module to the steering wheel body, the lateral legs of the first positioning feature are resiliently bent away by the second positioning feature and return to their non-bent initial state when the mounting process is finished.

Starting form this prior art it is an object of the invention to improve the steering wheel and especially its airbag module in such a way that the airbag module can be mounted to the steering wheel body more easily.

This task is solved by a steering wheel having the features of claim 1 . An airbag module adapted for being a part of such a steering wheel is defined in claim 14.

When the airbag module is mounted to the steering wheel body, the first positioning feature, namely the lateral legs of the latter, are resiliently deflected because the cross-piece is pushed away by the second positioning feature during the airbag module insertion. This movement usually takes place in a radial direction. Due to the lever effect, the elastic deformation of the lateral legs of the first positioning feature takes place mainly at their module-side end. According to the invention, the thickness of each of the lateral legs of the first positioning feature is reduced in its module-side end portion. By this measure, the effect that the lateral legs are deformed mainly at their housing-side end is enhanced such that the module-side ends portions of the lateral legs almost works like a hinge in the radial direction.

In order to enhance the “hinge effect” it can be preferred to make the moduleside end portion relatively short, especially shorter than the cross-piece-side end portion.

In order to enhance the “hinge effect” and optimize the volume of the module, the lateral legs are connected to a housing floor. In other words, the lateral legs are not connected to a housing side wall.

The module-side end portion with the reduced thickness does not necessarily extend completely to the housing section. It is also possible the thickness enlarges again towards the housing section such that the respective lateral leg has a “waist”. In a preferred embodiment, the first positioning feature is made of plastic which allows to management the thickness evolution in a simpler and cheaper way. In this case it is often further preferred that the first positioning feature is one- pieced with the housing section (the housing element, to which the housing section and the first positioning feature belong, is often a one-pieced plastic part).

Often is desired (or needed) to dimension the first positioning feature such that it can withstand the forces that occur when the airbag module is fired and the airbag cushion deploys. Especially at the end of the airbag deployment, high pulling forces act on the lateral legs. In order to compensate for the reduced thickness, it is thus preferred that each lateral leg has a first width in its moduleside end portion and a second width at its cross-piece-side end portion, wherein the second width is smaller than the first width. “Width” means the extension in a circumferential direction (substantially perpendicular to a radial direction), and “thickness” means the extension in radial direction.

Since the tensile strength (the factor that determines the pulling force that each lateral leg can withstand) depends essentially on the cross-sectional area, it is preferred that each of the lateral legs of the first positioning feature has a substantially constant cross-sectional area, preferably in a range of 5% to 10%, along its entire length (in axial direction) of the lateral legs, such that no “predetermined breaking point” is generated. In this case, the second moment of area is variable, whereas the cross-sectional area remains substantially constant.

In order to safely avoid a breakage of the cross-piece, it will often be preferred that the cross-piece has a thickness that is even larger than the thickness of the cross-piece-side end portion. When viewed from the side, one can in this case distinguish at least three portions with different thicknesses: The module-side end portion, the cross-piece side end portion and the cross-piece. Often, an intermediate portion in which the thickness gradually increases will be provided between the module-side end portion and the cross-piece-side end portion. In any case, the cross-piece is to be distinguished from the lateral legs carrying the cross-piece: making only the cross-piece thicker will not lead to the desired effect.

In a preferred embodiment, the cover is snapped to a housing section of the housing element by means of snap-in-features. In order to prevent the cover from unsnapping from the housing section during deployment of the airbag cushion, a locking plate locking the snap-in-features to the housing element can be provided. This locking plate prevents any movement of the snap-in features of the cover, once the airbag module is completely assembled. The locking plate usually extends along the outside of a housing floor and is attached to the same after the cover has been snapped to the housing section. Sections of the edge of the locking plate extend to the snap-in features of the cover such that they cannot move radially inward to an extend that would allow an unsnapping from the housing section.

In a further preferred embodiment, the airbag module further comprises a limiting feature in the vicinity of the first positioning feature. This limiting feature is arranged to limit the displacement of the first positioning feature in order to prevent a breakage of the first positioning feature during a disassembly procedure. This limiting feature allows a movement of the first positioning feature (which is necessary during the assembly as well as during a disassembly), but limits this displacement such that a breakage due to a too large displacement is prevented. This limiting feature preferably extends parallel to the lateral legs of the first positioning feature. The advantage of providing such a limiting feature is the following: When the airbag module is mounted to the steering wheel body, the U-shaped first positioning feature is “automatically” displaced by the second positioning feature of the steering wheel body, such that there is no risk of a too strong displacement. But in case of a disassembly, the first positioning feature must often be displaced (meaning bent) manually and so there is a risk that the first positioning feature is bent too far and breaks. If this happens, usually the whole airbag module must be thrown away. Providing a limiting feature safely prevents that. Such a limiting feature is especially useful since due to the reduced thickness of the lateral legs at their module-side end, the first positioning feature can easily be bent in the radial direction (as desired), but this could lead to an undesired breakage during a disassembly if no limiting feature is provided.

The limiting feature can be in form of at least one protrusion of the locking plate. This makes it especially easy to provide the necessary stability for the limiting feature, since the locking plate is often made of sheet metal. Since the locking plate is usually a stamped and bent part, no additional production step might be necessary (the limiting feature is formed by the bending process which is necessary anyway).

Alternatively, the limiting feature can be in form of at least one protrusion of the housing element. In this case, the locking plate often has a recess or an opening at the position of the limiting feature.

The invention will now be described in more detail by means of preferred embodiments in view of the figures. The figures show:

Figure 1 : all relevant elements of a first embodiment of an inventive steering wheel in a strongly schematic cross-sectional representation,

Figure 2: a sub-assembly of an airbag module being formed from elements being shown in Figure 1 ,

Figure 3: the complete airbag module in a representation according to Figure 2,

Figure 4: all elements being shown in Figure 1 in a completely assembled state,

Figure 5: the cover of Figure 1 in a bottom view from direction R1 in Figure 1 , Figure 6: the housing element shown in Figure 1 in a bottom view from direction R2 in Figure 1 ,

Figure 7: the locking plate shown in Figure 1 in a bottom view from direction R3 in Figure 1 ,

Figure 8: the armature shown in Figure 1 in a plan view from direction R4 in Figure 1 ,

Figure 9a: the first and third positioning feature of the housing element shown in Figure 1 in a side view from direction R5 in Figure 1 ,

Figure 9b: the first positioning feature shown in Figure 9a in a side view from direction R7 in Figure 9a,

Figure 10a: a variation of a first positioning feature in a representation according to Figure 9a,

Figure 10b: the first positioning feature shown in Figure 9a in a representation according to Figure 9b,

Figure 11 : a hook of the housing element of Figure 1 in a side view from direction R6 in Figure 1 ,

Figure 12: a complete steering wheel according to a second embodiment of the invention in a detailed perspective view,

Figure 13: the steering wheel of Figure 12 in a plan view from above,

Figure 14: a sectional view taken along plane A-A in Figure 13,

Figure 15: the locking plate of the second embodiment in a perspective view, Figure 16: a third embodiment of the invention in a representation according to Figure 4,

Figure 17: a detail of the embodiment of Figure 16 but in a more detailed and prospective view,

Figure 18: a first positioning feature in a further embodiment,

Figure 19: a first positioning feature in a further embodiment, and

Figure 20 a detailed sectional view through a lateral leg and the cross-piece carried by this lateral leg and another lateral leg

In view to Figures 1 to 10 a first embodiment of the invention is described. The representations are strongly schematic such that the relevant features can be seen clearly.

Figure 1 shows elements of an airbag module as well as a part of a steering wheel body, namely an armature. Of course (and as will be seen later), the complete steering wheel body comprises more elements like a rim, spokes and the like, but these elements are not relevant for the invention such that they are not shown in the Figures 1 to 10 of the first embodiment. Further, coil springs acting between the airbag module and the armature 17 are shown in Figure 1. Figures 5 to 10 show details of elements shown in Figure 1 .

The airbag module comprises a cover 20 (Figures 1 and 5), a housing element 30 (Figures 1 and 6), a locking plate 50 (Figures 1 and 7), an airbag cushion 90, and an inflator 95. First, the elements of the airbag module are described:

As has just been mentioned, the cover 20 of the airbag module is shown in Figures 1 and 5. This cover 20 is usually made from a plastic material and comprises a cover sidewall 24 and a roof 22. Snap-in features 26 in form of snap-in hooks 26 extend from the lower edge of the cover sidewall 24 as is generally known in the field of airbag modules. As has also already been mentioned, the housing element 30 is shown in Figures 1 and 6. This housing element 30 is usually a one-pieced plastic part and comprises a housing section 31 . This housing section 31 and cover 20 form (in the assembled state) an accommodation for the airbag cushion 90. The housing section 31 comprises a housing floor 32 and a housing sidewall 34. The housing floor 32 comprises at least one hole 36 for receiving the snap-in features 26 of the cover such that the cover 20 can be snapped to the housing section 31 .

The housing floor 32 further comprises a hole 37 for the inflator 95, protrusions 39 for the coil springs 60 and holes 38 for attaching the locking plate 50. The housing floor 32 can further comprise attachment means for horn contacts but those are not shown in Figures 1 to 10.

In order to attach the housing element 30 (and thus the whole airbag module) to the steering wheel body (in the embodiment shown the steering wheel armature 17), the housing element 30 of the first embodiment further comprises the following features:

Two hooks 40a, 40b serving as first and second mounting features extend from the housing floor 32 (please see Figures 1 , 6 and 10). Those hooks 40 are rather solid and can withstand the forces which can occur when the airbag cushion 90 is deployed by the inflator 95.

Further, a U-shaped first positioning feature 42 extends from the housing section 31 to ensure a correct positioning of the airbag module 10, in particular along the mounting axis of the airbag module on the steering wheel body. This first positioning feature 32 comprises two lateral legs 46 and a cross-piece 44 connecting those lateral legs 46 (please see Figures 1 , 6, 9a, and 9b). This first positioning feature extends substantially from an edge of the housing floor and is located on a center-line; the two hooks 40a, 40b are usually arranged symmetrically relative to this center-line C. As can best be seen from Figures 9a and 9b, the width (in circumferential direction) of the lateral legs 46 decreases from their module-side end towards the module-far end (Figure 9a) while their thickness (in radial direction) increases (Figure 9b). The increase thickness and the decrease in width is preferably such that the cross-sectional area remains essentially constant. In the embodiment shown, the lateral legs have first portion (module-side portion) 46a with a first width and thickness, an intermediate portion 46b, in which the width decreases and the thickness increases, and a second section (cross- piece-side portion) 46c with a second width and thickness. This enhances the flexibility in radial direction without lowering the tensile strength and thus reduces the effort needed to snap-in the airbag module 10 on the steering wheel armature 70 without lowering the force it can withstand when the airbag module is fired. Due to the presence of the limiting feature, the enhanced flexibility does not increase the risk of a breakage.

Shaping the lateral legs with three distinct portions as just show is often preferred in order to define a “hinge area” in in the first portion 46a, but is not strictly mandatory.

Further it needs to be mentioned that the location with the smallest thickness does not need to be directly at the module-side end of the lateral legs 46, it is sufficient that it is located in the module-side end portion, preferably at or close to the junction with the housing section 31. It is for example possible that the lateral legs have a “waist” in the module-side end portion. A variation to the embodiment of Figures 9a and 9b having such a waist is shown in Figures 10a and 10b.

In the embodiment shown, the housing element 30 further comprises two posts 48 being located between the lateral legs 46 of the first positioning feature 42; those posts 48 form a third positioning feature. The posts 48 extend parallel to each other at a distance D1 (Figure 9). The posts are (as the rest of the housing element) made of a plastic material and since they have free ends, they can to some extend be deformed, especially in the directions indicated by the arrows in Figure 9. In order to secure the cover 20 once it has been snapped to the housing section 31 , a locking plate 50 is provided (please see Figures 1 and 7). This locking plate 50 preferably is a one-pieced sheet metal part. This locking plate 50 comprises a hole 54 for the inflator, attachment holes 56 for attaching (for example screwing or riveting) the locking plate 50 to the housing floor 32 and holes 58 for the protrusions 39. Further, this locking plate 50 has an embayment 53 at the position of the U-shaped first positioning feature 42 of the housing element 30 and a protrusion 52 being formed of a bent-away section and forming a limiting feature adjacent to the embayment 53.

The steering wheel armature 17 (please see Figures 1 and 8) comprises a hole 72 for each hook 40a, 40b and a mounting spring 74 is held at the lower surface of the steering wheel armature such that the hooks 40a, 40b can be snapped to this mounting spring 74 as is generally known in the prior art. A common mounting spring 74 can be provided or a separate mounting spring can be provided for each hook 40a, 40b. According to the definition chosen in this application, the mounting spring forms a part of the third and fourth mounting feature cooperating with the first and second mounting features (the hooks 40a, 40b), and the mounting spring is a part of the steering wheel body. Thus, the first to fourth mounting features participate to the attachment of the airbag module 10 on the steering wheel body. Similar to the housing floor, protrusions 78 for positioning the coil springs are provided at the steering wheel armature 70.

Further, a second positioning feature 76 in form of a hook is provided for the first positioning feature 42 of the housing element 30. This positioning feature 76 comprises a lower contact surface 76a for contacting the cross-piece 44 of the first positioning feature such that an axial positioning (Z-positioning I positioning along the mounting axis of the airbag module 10 or positioning along a steering column axis) is generated. Further, the second positioning feature 76 has lateral surfaces 76b, 76c that are spaced by a distance D2. This distance D2 is equivalent or nearly equivalent to the distance D1 between the two posts of the third positioning feature. Figure 2 shows a sub-assembly of the airbag module 10. This sub-assembly is comprised of the cover 20, the housing element 30, the airbag cushion 90 and the inflator 95. One can see that the cover 20 is snapped to the housing element 30 (namely the housing floor 32) via the snap-in hooks 26 which extend through the holes 36.

In a subsequent assembly step the locking plate 50 is attached to the housing floor, 32, for example via studs provided on the inflator 95. The outcome of this assembly step is shown in Figure 3 which shows the complete airbag module 10. One can see that the locking plate 50 extends to the inner edges of the snap-in hooks 26 such that they are prevented from unsnapping even if high pushing forces are applied to the cover when the airbag cushion 19 deploys. One can also see from Figure 3 that the protrusion 52 (the limiting feature) is located in the vicinity of the U-shaped first positioning feature 42 but has some distance from this positioning feature 42 such that the positioning can bend inwards (see arrow in Figure 3), but only to some extent.

Figure 4 shows the airbag module of Figure 3 being mounted (namely snapped) to the steering wheel armature 70. During this assembly step, the mounting spring 74 and the U-shaped first positioning feature 42, namely its lateral legs 46, are resiliently deformed. The distance between the U-shaped first positioning feature 42 and the protrusion (limiting feature) 52 of the locking plate allows a deflection of the U-shaped first positioning feature 42 sufficient for this assembly step but hinders the U-shaped positioning feature 42 from being bent more than necessary for this assembly step.

In the completely assembled state, the coils springs are pre-tensioned and the cross-piece 44 of the U-shaped first positioning feature is thus pressed against the lower contact surface 76a of the second positioning feature 76 such that an axial positioning is generated. Further, the second positioning feature 76 is positioned between the posts 48 of the third positioning feature such that a positioning in the circumferential direction is generated. Figures 12 to 15 show a second embodiment similar to the first embodiment, but in more detailed representations. The difference is that the airbag module 10 of the second embodiment does not show a third positioning feature between the lateral legs of the first positioning feature, such that the second positioning feature 76 of the steering wheel body only interacts with the first positioning feature of the airbag module and the second positioning feature does not contribute to the positioning in the circumferential direction. Besides that, the description of the first embodiment can directly be applied to the second embodiment and like elements are denoted with like reference numbers.

Figures 16 and 17 show an embodiment that is also similar to the first embodiment. Here, the difference is that the limiting feature is not a part of the locking plate, but is a part of the housing element 30. In the example embodiment, the limiting feature is in form of two protrusions 49 extending from the housing floor 32 (see Figure 16) and through the embayment of the locking plate 50.

Figures 18 and 19 show alternative designs of the first positioning feature 40. As described above in view to Figures 9a, 9b, 10a, and 10b, the width (in circumferential direction) of the lateral legs 46 decreases from their module-side end towards the module-far end while their thickness (in radial direction) increases such that the cross-sectional area remains essentially constant.

Figure 20 shows a detailed cross-section through one lateral leg 46 and the cross-piece 44 of an U-shaped positioning feature in which one can see some more possible (but not mandatory) features in more detail: The first portion 46a (module-side portion; the portion with the minimum thickness) does not extend completely tom the housing section; the lateral leg widens again in a junction 47 to the housing section. Further, one can see that the length I2 of the second portion 46c (cross-piece-side portion) exceeds the length I1 of the first portion 46a. Providing a relatively short first portion enhances the “hinge effect”. The length I2 can be defined between two and ten times greater than the length 11. Finally, it is shown that the cross-piece can have a larger thickness than the second portion 46c.

List Of reference numbers

5 steering wheel

10 airbag module

20 cover

22 roof of cover

24 cover sidewall

26 snap-in hooks (snap-in features)

30 housing element

31 housing section

32 housing floor

34 housing sidewall

36 hole for snap-in hooks of cover

37 hole for inflator

38 hole for attaching locking plate

39 protrusion for coil spring

40a first hook (first mounting feature)

40b second hook (second mounting feature)

42 U-shaped first positioning feature

44 cross-piece

46 lateral leg

46a first portion (module-side portion)

46b intermediate portion

46c second portion (cross-piece-side portion)

47 junction to the housing section

48 third positioning feature (post between lateral legs)

49 protrusion from housing element / limiting feature

50 locking plate

52 protrusion (bent-away section/ limiting feature)

53 embayment

54 hole for inflator

56 attachment hole 58 hole for protrusion 39

60 coil spring

70 steering wheel armature (part of steering wheel body)

72 hole for hook (part of third and fourth mounting feature) 74 mounting spring (part of third and fourth mounting feature)

76 second positioning feature

76a lower contact surface

76b, 76c lateral surface

78 protrusion for coil spring 80 spoke (part of steering wheel body)

82 rim (part of steering wheel body)

90 airbag cushion

95 inflator

C center line h length of first portion

I2 length of second portion

Claims

1 . Steering wheel (5) comprising an airbag module (10) comprising

- a housing element (30) comprising a housing section (31 ),

- an inflator (95) attached to the housing section (31 ),

- a cover (20) attached to the housing section (31 ),

- an airbag cushion (90) being accommodated in an accommodation unit being defined by the housing section (31 ) and the cover (20), wherein the housing element (30) comprises a first mounting feature (40), a second mounting feature (40), and a resiliently flexible, U-shaped first positioning feature (42) extending from the housing section (31 ) of the housing element (30), said first positioning feature (42) having two lateral legs (46) and a cross-piece (44) connecting the two lateral legs, and

- a steering wheel body having a hub area for receiving at least a section of the airbag module (10), said steering wheel body having a third mounting feature co-operating with the first mounting feature (40), a fourth mounting feature co-operating with the second mounting feature (40), and a second positioning feature (76) having a lower contact (76a) surface co-operating with the cross-piece (44) of the first positioning feature (42), characterized in that each of the lateral legs (46) of the first positioning feature (42) has a first thickness in its module-side end portion, preferably at the junction with the housing section (31 ), and a second thickness in its cross-piece-side end portion, preferably at the level of the cross-piece (44), wherein the first thickness is smaller than the second thickness.

2. Steering wheel according to claim 1 , characterized in that each of the lateral legs (46) of the first positioning feature (42) has a first width at the location of the first thickness and a second width at the location of the second thickness, wherein the second width is smaller than the first width.

3. Steering wheel according to claim 2, characterized in that each of the lateral legs (46) of the first positioning feature (42) has a first cross- sectional area at its module-side end and a second cross-sectional area at its cross-piece-side end, wherein the first cross-sectional area and the second cross-sectional area are substantially equal.

4. Steering wheel arrangement according to any one of the preceding claims, characterized in that the cover (20) is attached to the housing section (31 ) via snap-in features (26) and that the airbag module (10) further comprises a locking plate (50) for locking the snap-in features.

5. Steering wheel unit according to any one of the preceding claims, characterized in that the airbag module further comprises a limiting feature in the vicinity of the first positioning feature (42), said limiting feature arranged to limit the displacement of the first positioning feature (42).

6. Steering wheel unit according to claim 5, characterized in that the limiting feature is in form of at least one protrusion (49, 52) extending essentially parallel to the lateral legs (46) of the U-shaped positioning feature (42).

7. Steering wheel unit according to claim 6, characterized in that the at least one protrusion (49) is a part of the housing element (30), wherein the at least one protrusion preferably extends from a housing floor (32) receiving the inflator (95).

8. Steering wheel unit according to claims 4 and 5, characterized in that the at least one protrusion (52) is a part of the locking plate (50).

9. Steering wheel according to one of the preceding claims, characterized in that a third positioning feature extends between the lateral legs (46) of the first positioning feature (42), said third positioning feature cooperating with the second positioning feature (76). Steering wheel according to claim 9, characterized in that the third positioning feature is in form of two posts (48) and that the second positioning feature (76) extends between the two posts (48). Steering wheel according to any one of the preceding claims, characterized in that the first mounting feature is a first hook (40a) and the second mounding feature is a second hook (40b), wherein the first hook (40a) and the second hook (40b) are preferably rigid. Steering wheel unit according to claim 9, characterized in that the first hook (40a) is located at the 3 o’ clock position, the second hook (40b) is located at the 9 o’ clock position ant that the first positioning feature (42) is located at the 12 o’ clock position. Steering wheel according to any one of the preceding claim, characterized in that at least one pre-tensioned spring (60) is provided between the airbag module (10) and the steering wheel body in such a way that the airbag module can be pressed down towards the steering wheel body. Airbag module (10) being adapted for being a part of a steering wheel according to any one of the claims 1 to 11 and comprising

- a housing element (30) comprising a housing section (31 ),

- an inflator (95) attached to the housing section (31 ),

- a cover (20) attached to the housing section (31 ), and

- an airbag cushion (90) being accommodated in an accommodation unit being defined by the housing section (31 ) and the cover (20), wherein the housing element (30) comprises a first mounting feature (40), a second mounting feature (40), and a resiliently flexible, U-shaped first positioning feature (42) extending from the housing section (31 ) of the housing element (30), said first positioning feature (42) having two lateral legs (46) and a cross-piece (44) connecting the two lateral legs, characterized in that each of the lateral legs (46) of the first positioning feature (42) has a first thickness in its module-side end portion, preferably at the junction with the housing section (31 ), and a second thickness in its cross-piece-side end portion, preferably at the level of the cross-piece (44), wherein the first thickness is smaller than the second thickness.