Steering wheel with airbag module

Abstract

A steering wheel comprising an airbag module (10) and a steering wheel body is described. The airbag module illustrates a housing element comprising a housing section and a first positioning feature (42) extending from the housing section. The first positioning feature (42) is adapted to cooperate with a second positioning feature (76) of the steering wheel body. The first positioning feature (42) has two side legs (46) and a cross member (44) connecting the two side legs (46). To improve positioning without enlarging the footprint of the airbag module, a third positioning feature (48) extends between the side legs (46) of the first positioning feature (42). The third positioning feature (48) also cooperates with the second positioning feature (76).

Description

[0001] The invention relates to a steering wheel for a vehicle according to the preamble of claim 1 and to an airbag module according to the preamble of claim 15 which is suitable as part of such a steering wheel.

[0002] Such a steering wheel comprises a steering wheel body and an airbag module which is mounted to the steering wheel body, in particular in such a way that the airbag module can be pressed towards the steering wheel body in order to activate the vehicle's horn (so-called “floating module concept”).

[0003] For example, a universal steering wheel is known from CN 212604810 A. The airbag module of the steering wheel comprises a housing element having a housing section, an inflator attached to the housing section of the housing element, a cover attached to the housing section via a snap feature, and an airbag cushion accommodated in a accommodating unit 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. Both the mounting feature and the positioning feature extend from the housing section and are components of the housing element. The first positioning feature has two side legs and a transverse member connecting the two side legs. The steering wheel body has a hub area for receiving the airbag module, and comprises a third mounting feature cooperating with the first mounting feature, a fourth mounting feature cooperating with the second mounting feature, and a second positioning feature having a lower contact surface cooperating with the transverse member of the first positioning feature. This means that, in the unpressed state of the airbag module, the cross piece of the first positioning feature and the lower contact surfaces of the second positioning feature contact each other so that the axial position of the first positioning feature relative to the second positioning feature defines the first positioning feature. During the process of mounting the airbag module to the steering wheel body, the side legs of the first positioning feature are elastically bent by the second positioning feature and return to their non-bent initial state when the mounting process is completed.

[0004] Starting from this prior art, it is an object of the present invention to improve the positioning of the airbag module to the steering wheel body.

[0005] This object is achieved by a steering wheel having the features of claim 1. An airbag module suitable for use as part of such a steering wheel is defined in claim 15 .

[0006] The first and second positioning features are used only for axial positioning (according to the mounting axis of the airbag module or the rotation axis of the steering wheel). This means that only the cross piece of the first positioning feature and the corresponding contact surfaces of the second positioning feature are in contact with each other (when the airbag module is not pressed), while the side legs never come into contact with the second positioning feature.

[0007] According to the present invention, the third positioning feature extends between the side legs of the first positioning feature and also cooperates with the second positioning feature. The third positioning feature can be in the form of two cylindrical members (a first cylindrical member and a second cylindrical member), and the second positioning feature can be in the form of a tongue and / or hook extending between the two cylindrical members and having a lower contact surface of the transverse member adjacent to the first positioning feature. The cylindrical member does not contact the lower contact surface, but the first cylindrical member is usually in contact with the first side surface of the second positioning feature, and the second cylindrical member is usually in contact with the second side surface of the second positioning feature. The two cylindrical members preferably extend parallel to each other and the two side surfaces are basically directed away from each other. In the case where the two side surfaces are flat, they are usually parallel to each other. Therefore, the positioning in the radial plane in addition to the positioning in the Z direction (axial direction; direction of the steering column) is achieved without using any additional space (the occupied area of ​​the airbag module is not enlarged).

[0008] The columns preferably come into contact with the second positioning features only in a limited area, preferably along less than half of their length, in order to limit friction. They are preferably arranged to come into contact with the second positioning features only at the end of the assembly movement of the airbag module on the steering wheel. This can be achieved if the second positioning features are in the form of hooks with an inclined portion arranged to limit the surface of the side surfaces of the second positioning features to contact with the columns. This reduces friction during the final assembly step (when the airbag module is inserted into the steering wheel body) and during operation of the horn (when the airbag module is pressed by the driver).

[0009] The column preferably has a certain flexibility and for this reason and because the column is not connected via a cross-piece (as the side legs of the first locating feature do), a high clamping force is prevented from being generated between the column of the second and third locating features despite the fact that each column contacts the side surface. Such a high clamping force is not required because it would counteract the effect of axial positioning and would also not be conducive to the easy pressing down of the module to activate the operation of the horn. By this arrangement, a good centering of the airbag module on the steering wheel body is achieved.

[0010] Since the pillars do not need to withstand the large forces generated when the airbag module is triggered (in which case the first locating feature is retained by the second locating feature), they can be relatively "weak", and this also contributes to the small clamping force between the third locating feature and the second locating feature.

[0011] In a preferred embodiment, the cover is snapped to the housing section of the housing element using snap features. In order to prevent the cover from being unsnapping from the housing section during deployment of the airbag cushion, a locking plate may be provided which locks the snap features to the housing element. This locking plate prevents any movement of the snap features of the cover once the airbag module is fully assembled. The locking plate typically extends along the outside of the housing base plate and is attached to the housing base plate after the cover has been snapped to the housing section. Sections of the edges of the locking plate extend to the snap features of the cover so that they cannot be moved radially inwards to such an extent as to allow unsnapping from the housing section.

[0012] In another preferred embodiment, the airbag module further comprises a limiting feature near the first positioning feature. The limiting feature is arranged to limit the displacement of the first positioning feature so as to prevent the first positioning feature from being damaged during the disassembly process. The limiting feature allows the movement of the first positioning feature (which is necessary during assembly and during disassembly), but limits the displacement so as to prevent damage caused by too large a displacement. The limiting feature preferably extends parallel to the side legs of the first positioning feature. The advantages of providing such limiting features are as follows: 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, so that there is no risk of too strong displacement. However, in the case of disassembly, the first positioning feature must often be manually displaced (meaning bent), and there is therefore a risk that the first positioning feature bends too far and breaks. If this happens, the entire airbag module must usually be discarded. Providing limiting features safely prevents this situation.

[0013] The restriction feature may be in the form of at least one protrusion of the locking plate. This makes it particularly easy to provide the restriction feature with the necessary stability, since the locking plate is usually made from sheet metal. Since the locking plate is usually a stamped and bent component, additional production steps may not be necessary (the restriction feature is formed by the necessary bending process anyway).

[0014] Alternatively, the restriction feature may be in the form of at least one protrusion of the housing element. In this case, the locking plate typically has a recess or opening at the location of the restriction feature.

[0015] As mentioned, when the airbag module is mounted to the steering wheel body, the first positioning feature, i.e. the side leg of the first positioning feature, needs to be elastically deflected because the cross piece will be pushed away by the second positioning feature during the insertion of the airbag module. This movement usually occurs in the radial direction. In order to reduce the required force, it may be preferred that each side leg of the first positioning feature has a first thickness at its module-side end and a second thickness at its cross-piece-side end, wherein the first thickness is less than the second thickness. Since it is preferred that the tensile strength is substantially constant along the length of each side leg (to avoid any breakage when the inflator is triggered and the airbag is deployed), it is further preferred that each side leg has a first width at its module-side end and a second width at its cross-piece-side end, wherein the second width is less than the first width. "Width" refers to the extension in the circumferential direction (substantially perpendicular to the radial direction), and "thickness" refers to the extension in the radial direction. Since tensile strength depends primarily on cross-sectional area, it is preferred that each of the side legs of the first locating feature has a first cross-sectional area at its module-side end and a second cross-sectional area at its cross-member-side end, wherein the first and second cross-sectional areas are substantially equal.

[0016] The present invention will now be described in more detail using preferred embodiments according to the accompanying drawings. The accompanying drawings show:

[0017] Figure 1 : a strongly schematic cross-sectional representation of all relevant elements of a first embodiment of the inventive steering wheel,

[0018] Figure 2 :Depend on Figure 1 The components shown form a subassembly of an airbag module,

[0019] Figure 3 :according to Figure 2 The complete airbag module in the representation,

[0020] Figure 4 : In fully assembled state Figure 1 All components shown,

[0021] Figure 5 :from Figure 1 The direction R1 is observed Figure 1 Bottom view of the cover,

[0022] Figure 6 :from Figure 1 The direction R2 is observed Figure 1 A bottom view of the housing element is shown,

[0023] Figure 7 :from Figure 1 The direction R3 is observed Figure 1 Bottom view of the locking plate shown,

[0024] Figure 8 :from Figure 1 The direction R4 is observed Figure 1 The plan view of the skeleton shown,

[0025] Fig. 9 :from Figure 1 The direction R5 is observed Figure 1 A side view of the first and third locating features of the housing element is shown,

[0026] Fig.10 :from Figure 1 The direction of R6 is observed Figure 1 View of the hook of the housing element,

[0027] Fig.11 : A detailed perspective view of a complete steering wheel according to a second embodiment of the invention,

[0028] Fig.12 : Observed from above Fig.11 Plan view of the steering wheel,

[0029] Fig.13 :along Fig.12 The cross-sectional view taken by plane AA in

[0030] Fig.14 : A perspective view of a locking plate of a second embodiment,

[0031] Fig.15 :according to Figure 4 The third embodiment of the present invention is represented by

[0032] Fig.16 : Fig.15 but using a more detailed perspective,

[0033] Fig.17 :according to Fig. 9 Another embodiment of the first and second locating features of the present invention, and

[0034] Fig.17a :from Fig.17 The direction of R7 observation Fig.17 A side view of a first locating feature of the embodiment of the present invention.

[0035] Reference Figures 1 to 10 A first embodiment of the invention is described. The representations are strongly schematic so that the relevant features can be clearly seen.

[0036] Figure 1The elements of the airbag module and part of the steering wheel body, i.e. the skeleton, are shown. Of course (and as will be seen later), the complete steering wheel body comprises further elements, such as rim, spokes, etc., but these elements are not relevant to the present invention, so that they are not shown in the first embodiment. Figures 1 to 10 In addition, Figure 1 The helical spring acting between the airbag module and the frame 17 is shown in FIG. Figures 5 to 10 Shows Figure 1 Details of the components shown.

[0037] The airbag module includes a cover 20 ( Figure 1 and Figure 5 )、Shell element 30( Figure 1 and Figure 6 )、Lock plate 50( Figure 1 and Figure 7 ), airbag cushion 90 and inflator 95. First, the components of the airbag module are described:

[0038] As just mentioned, Figure 1 and Figure 5 2 shows a cover 20 of an airbag module. The cover 20 is typically made of a plastic material and includes a cover sidewall 24 and a top 22. A snap feature 26 in the form of a snap hook 26 extends from a lower edge of the cover sidewall 24, as is generally known in the art of airbag modules.

[0039] As already mentioned, Figure 1 and Figure 6 2 shows a housing element 30. The housing element 30 is typically a one-piece plastic component and comprises a housing section 31. The housing section 31 and the cover 20 (in the assembled state) form a housing for the airbag cushion 90. The housing section 31 comprises a housing bottom plate 32 and housing side walls 34. The housing bottom plate 32 comprises at least one hole 36 for receiving the snap feature 26 of the cover so that the cover 20 can be snapped to the housing section 31.

[0040] The housing bottom plate 32 also includes a hole 37 for the inflator 95, a protrusion 39 for the coil spring 60, and a hole 38 for attaching the locking plate 50. The housing bottom plate 32 may also include attachment means for the horn contact, but these are not shown. Figures 1 to 10 Shown in.

[0041] In order to attach the housing element 30 (and thus the entire airbag module) to the steering wheel body (in the embodiment shown the steering wheel skeleton 17), the housing element 30 of the first embodiment further comprises the following features:

[0042] Two hooks 40a, 40b, serving as first and second mounting features, extend from the housing bottom plate 32 (see FIG. Figure 1 , Figure 6 and Fig.10 ). These hooks 40 are quite strong and can withstand the forces that may be generated when the airbag cushion 90 is deployed by the inflator 95.

[0043] Furthermore, a U-shaped first positioning feature 42 extends from the housing section 31 to ensure the correct positioning of the airbag module 10, in particular along the mounting axis of the airbag module on the steering wheel body. The first positioning feature 32 comprises two side legs 46 and a cross piece 44 connecting these side legs 46 (see Figure 1 , Figure 6 and Fig. 9 ). The first positioning feature extends substantially from the edge of the housing bottom plate and is positioned on the center line; the two hooks 40a, 40b are generally arranged symmetrically relative to the center line C.

[0044] The housing element 30 also includes two cylindrical members 48b, 48c located between the side legs 46 of the first positioning feature 42; these cylindrical members 48 form a third positioning feature. The cylindrical members 48b, 48c extend parallel to each other at a distance D1 ( Fig. 9 ). The cylindrical members (as the rest of the housing element) are made of plastic material and, since they have free ends, they can be deformed to a certain extent, especially in Fig. 9 Deformation in the direction indicated by the arrow.

[0045] In order to secure the cover 20 after it has been snapped onto the housing section 31, a locking plate 50 is provided (see Figure 1 and Figure 7 ). The locking plate 50 is preferably a one-piece sheet metal component. The locking plate 50 includes a hole 54 for the inflator, an attachment hole 56 for attaching (e.g., screwing or riveting) the locking plate 50 to the housing bottom plate 32, and a hole 58 for the protrusion 39. In addition, the locking plate 50 has a bay 53 at the location of the U-shaped first positioning feature 42 of the housing element 30 and a protrusion 52 formed by a bent section and forming a limiting feature adjacent to the bay 53.

[0046] Steering wheel frame 17 (see Figure 1 and Figure 8) comprises a hole 72 for each hook 40a, 40b, and a mounting spring 74 is retained at the lower surface of the steering wheel skeleton so that the hooks 40a, 40b can be snapped into the mounting spring 74, as is generally known in the prior art. A common mounting spring 74 can be provided for each hook 40a, 40b or an independent mounting spring can be provided. According to the definition selected in this patent application, the mounting spring forms part of the third and fourth mounting features that cooperate with the first and second mounting features (hooks 40a, 40b), and the mounting spring is part of the steering wheel body. Therefore, the first to fourth mounting features participate in the attachment of the airbag module 10 to the steering wheel body. Similar to the housing bottom plate, a protrusion 78 for positioning the coil spring is provided at the steering wheel skeleton 70.

[0047] Furthermore, a second positioning feature 76 in the form of a hook is provided for the first positioning feature 42 of the housing element 30. The positioning feature 76 comprises a lower contact surface 76a for contacting the cross piece 44 of the first positioning feature, so that an axial positioning (Z positioning / or positioning along the mounting axis of the airbag module 10 or positioning along the steering column axis) is produced. Furthermore, the second positioning feature 76 has side surfaces 76b, 76c spaced apart by a distance D2. The distance D2 is equal to or almost equal to the distance D1 between the two columnar elements 48b, 48c of the third positioning feature, so that when the airbag module is mounted to the steering wheel body, the first columnar element 48b is in contact with the first side surface 76b and the second columnar element is in contact with the second side surface 76c.

[0048] Figure 2 A subassembly of the airbag module 10 is shown. The subassembly comprises a cover 20, a housing element 30, an airbag cushion 90 and an inflator 95. As can be seen, the cover 20 is snapped to the housing element 30 (ie, the housing floor 32) via snap hooks 26 extending through holes 36.

[0049] In a subsequent assembly step, the locking plate 50 is attached to the housing bottom plate 32, for example via studs provided on the inflator 95. The result of this assembly step is Figure 3 , which shows the complete airbag module 10. It can be seen that the locking plate 50 extends to the inner edge of the snap hook 26, so that even when a large thrust is applied to the cover when the airbag cushion 19 is deployed, it prevents them from being unfastened. Figure 3 It can also be seen that the protrusion 52 (limiting feature) is located near the U-shaped first positioning feature 42, but has some distance from the positioning feature 42 so that the positioning can be bent inwardly (see Figure 3 ), but only to a certain extent.

[0050] Figure 4The steering wheel frame 70 is shown mounted (i.e. snapped) to the steering wheel frame 70. Figure 3 During this assembly step, the mounting spring 74 and the U-shaped first locating feature 42 (i.e., its side legs 46) are elastically deformed. The distance between the U-shaped first locating feature 42 and the protrusion (limiting feature) 52 of the locking plate allows the deflection of the U-shaped first locating feature 42 to be sufficient for this assembly step, but prevents the U-shaped locating feature 42 from bending more than necessary for this assembly step.

[0051] In the fully assembled state, the coil spring is pretensioned, and the cross piece 44 of the U-shaped first positioning feature is therefore pressed against the lower contact surface 76a of the second positioning feature 76, so that axial positioning is produced. In addition, the second positioning feature 76 is positioned between the cylindrical pieces 48 of the third positioning feature, so that positioning in the circumferential direction is produced.

[0052] Figures 11 to 14 A second embodiment is shown which is similar to the first embodiment but is shown in more detail. The difference is that the airbag module 10 of the second embodiment does not show the third locating feature between the side legs of the first locating feature, so that the second locating feature 76 of the steering wheel body only interacts with the first locating feature of the airbag module, and the second locating feature does not contribute to the positioning in the circumferential direction. Apart from this, the description of the first embodiment is directly applicable to the second embodiment, and similar elements are indicated by similar reference numerals.

[0053] Fig.15 and Fig.16 An embodiment is shown which is also similar to the first embodiment. Here, the difference is that the restriction feature is not part of the locking plate, but part of the housing element 30. In the exemplary embodiment, the restriction feature is from the housing bottom plate 32 (see Fig.16 ) in the form of two protrusions 49 extending out of and through the bay-shaped portion of the locking plate 50.

[0054] Fig.17 and Fig.17a An alternative design of the first locating feature 40 is shown. Here, the width of the side legs 46 (in the circumferential direction) decreases from their module-side ends toward the module distal end, while their thickness (in the radial direction) increases so that the cross-sectional area remains substantially constant. This enhances flexibility in the radial direction without reducing tensile strength, and thus reduces the effort required to snap the airbag module 10 onto the steering wheel skeleton 70 without reducing the force that the airbag module can withstand when it is triggered. The enhanced flexibility does not increase the risk of breakage due to the presence of the restraining feature. As in other embodiments, the columnar members 48b, 48c are located between the side legs 46 of the first locating feature.

[0055] Reference numerals list

[0056] 5. Steering Wheel

[0057] 10 Airbag module

[0058] 20 Cover

[0059] 22 Top of cover

[0060] 24 Cover side wall

[0061] 26 snap hook (snap feature)

[0062] 30 Shell element

[0063] 31 Shell section

[0064] 32 Shell bottom plate

[0065] 34 Shell side wall

[0066] 36 Holes for snap hooks on cover

[0067] 37 Holes for inflator

[0068] 38 Holes for attaching locking plate

[0069] 39 Protrusion for coil spring

[0070] 40a First hook (first mounting feature)

[0071] 40b Second hook (second mounting feature)

[0072] 42 U-shaped first positioning feature

[0073] 44 Horizontal piece

[0074] 46 Side Leg

[0075] 46a First section (module side section)

[0076] 46b Middle section

[0077] 46c Second section (lateral section)

[0078] 48b, 48c Third locating feature (post between the side legs)

[0079] 49 Housing element / protrusion of limiting feature

[0080] 50 Locking plate

[0081] 52 protrusion (bend section / limiting feature)

[0082] 53 Bay

[0083] 54 Holes for inflator

[0084] 56 Attachment holes

[0085] 58 Hole for protrusion 39

[0086] 60 Coil spring

[0087] 70 Steering wheel frame (part of the steering wheel body)

[0088] 72 Hole for hook (part of the third and fourth mounting features)

[0089] 74 Mounting spring (part of the third and fourth mounting features)

[0090] 76 second positioning feature

[0091] 76a Lower contact surface

[0092] 76b, 76c side surface

[0093] 78 Protrusion for coil spring

[0094] 80 Spokes (part of the steering wheel body)

[0095] 82 Rim (part of the steering wheel body)

[0096] 90 Airbag Cushion

[0097] 95 Inflator

[0098] C Centerline

Claims

1. A steering wheel (5), comprising An airbag module (10), the airbag module comprising - a housing element (30), said housing element comprising a housing section (31), - an inflator (95) attached to the housing section (31), - a cover (20), which is attached to the housing section (31), - an airbag cushion (90) which is accommodated in a receiving unit 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), the first positioning feature (42) having two side legs (46) and a cross member (44) connecting the two side legs, and a steering wheel body having a hub area for receiving at least a portion of the airbag module (10), the steering wheel body having a third mounting feature cooperating with the first mounting feature (40), a fourth mounting feature cooperating with the second mounting feature (40), and a second locating feature (76) having a lower contact (76a) surface of the cross member (44) cooperating with the first locating feature (42), It is characterized in that A third locating feature extends between the side legs (46) of the first locating feature (42), the third locating feature cooperating with the second locating feature.

2. The steering wheel according to claim 1, characterized in that: The third locating feature is in the form of a first cylindrical member (48a) and a second cylindrical member (48b) and in that the second locating feature (76) extends between the two cylindrical members (48), wherein the two cylindrical members (48b, 48c) preferably extend parallel to each other.

3. The steering wheel according to claim 2, characterized in that: The second locating feature includes a first side surface (76b) in contact with the first column (48b) and a second side surface (76c) in contact with the second column (48c).

4. A steering wheel arrangement according to any one of the preceding claims, characterised in that The cover (20) is attached to the housing section (31) via a snap feature (26), and wherein the airbag module (10) further comprises a locking plate (50) for locking the snap feature.

5. Steering wheel unit according to any one of the preceding claims, characterized in that The airbag module further includes a restriction feature adjacent to the first locating feature (42), the restriction feature being arranged to restrict displacement of the first locating feature (42).

6. The steering wheel unit according to claim 5, characterized in that The restraining feature is in the form of at least one protrusion (49, 52) extending substantially parallel to the side leg (46) of the U-shaped locating feature (42).

7. The steering wheel unit according to claim 6, characterized in that The at least one protrusion (49) is 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 part of the locking plate (50).

9. A steering wheel according to any one of the preceding claims, characterised in that Each of the side legs (46) of the first locating feature (42) has a first thickness at its module-side end and a second thickness at its cross-member-side end, wherein the first thickness is less than the second thickness.

10. The steering wheel according to claim 9, characterized in that Each of the side legs (46) of the first locating feature (42) has a first width at its module-side end and a second width at its cross-member-side end, wherein the second width is less than the first width.

11. The steering wheel according to claim 10, characterized in that Each of the side legs (46) of the first locating feature (42) has a first cross-sectional area at its module-side end and a second cross-sectional area at its cross-member-side end, wherein the first and second cross-sectional areas are substantially equal.

12. A steering wheel according to any one of the preceding claims, characterised in that The first mounting feature is a first hook (40a) and the second mounting feature is a second hook (40b), wherein the first hook (40a) and the second hook (40b) are preferably rigid.

13. The steering wheel unit according to claim 12, characterized in that The first hook (40a) is positioned at the 3 o'clock position, the second hook (40b) is positioned at the 9 o'clock position, and the first locating feature (42) is positioned at the 12 o'clock position.

14. A steering wheel according to any one of the preceding claims, characterised in that At least one pre-tensioned spring (60) is arranged between the airbag module (10) and the steering wheel body in such a way that the airbag module can be pressed toward the steering wheel body.

15. An airbag module (10) adapted to be part of a steering wheel according to any one of claims 1 to 14 and comprising - a housing element (30), said housing element comprising a housing section (31), - an inflator (95) attached to the housing section (31), - a cover (20), which is attached to the housing section (31), - an airbag cushion (90) which is accommodated in a receiving unit 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), the first positioning feature (42) having two side legs (46) and a cross member (44) connecting the two side legs, wherein the first locating feature (42) is adapted to cooperate with a second locating feature (76) of the steering wheel, It is characterized in that A third locating feature extends between the side legs (46) of the first locating feature (42), the third locating feature cooperating with the second locating feature.

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