Steering wheel with airbag module

Abstract

A steering wheel comprising an airbag module (10) and a steering wheel body is described. The airbag module shows a housing element and a cover (20) connected to the housing element by a snap feature (26) of the cover (20). The housing element has a housing section (31) 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 of the steering wheel body. The first positioning feature has two side legs and a cross member connecting the two side legs. To improve the overall integrity of the airbag module, the airbag module further includes a locking plate (50) for locking the snap feature (26) of the cover (20) and a limiting feature (52) located proximate the first positioning feature (42). The limiting feature (52) is arranged to limit displacement of the first positioning feature (42).

Description

[0001] The invention relates to a steering wheel for a vehicle according to the preamble of claim 1 and to an airbag module suitable as part of such a steering wheel according to the preamble of claim 12 .

[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, the object of the present invention is to increase the reliability of such steering wheels.

[0005] This object is achieved by a steering wheel having the features of claim 1. Claim 12 defines an airbag module which is suitable as part of such a steering wheel.

[0006] During the service life of a steering wheel as described above, two "abnormal" events may occur with respect to the airbag module. The first is the activation of the inflator, resulting in the deployment of the airbag cushion. Of course, while the airbag cushion is deployed, the cover should be prevented from being unfastened from the housing element. The second "abnormal" event is the removal of the airbag module from the steering wheel body for maintenance purposes. In this case, a controlled unfastening of the module is required without any damage occurring.

[0007] In order to prepare the airbag module for the above two events, the airbag module also includes two additional features. The first additional feature prevents the cover from being unfastened from the shell section when the airbag cushion is deployed, and the second additional feature prevents the first locating feature from being damaged when the first locating feature needs to be deformed during the removal process.

[0008] The locking plate for locking the snap feature of the cover can prevent the cover from being unfastened from the housing section because a thrust is transmitted to the inside of the top of the cover when the airbag is first deployed, in particular before at least one of the top doors is opened. The locking plate prevents any movement of the snap feature of the cover once the airbag module is fully assembled. The locking plate typically extends along the outside of the housing bottom plate and is attached to the housing bottom plate after the cover has been snapped to the housing section. Sections of the edges of the locking plate extend to the snap feature of the cover so that they cannot move radially inwards to such an extent as to allow unfastening from the housing section.

[0009] During disassembly, the first positioning feature can be prevented from being damaged by a limiting feature near the first positioning feature. The limiting feature allows the movement of the first positioning feature (which is necessary during assembly and during disassembly), but limits the displacement so that damage caused by too large a displacement is prevented. The limiting feature preferably extends parallel to the side legs of the first positioning feature. The advantage of providing such a limiting feature is 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 a 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 usually has to be discarded. Providing a limiting feature safely prevents this situation.

[0010] In a first preferred embodiment, the restriction feature is 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).

[0011] In an alternative embodiment, the restriction feature is 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.

[0012] It is generally preferred that the first and second positioning features are used only for axial positioning. 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. In this case, if positioning in a radial plane is also required, it is preferred that a third positioning feature extends between the side legs of the first positioning feature cooperating with the second positioning feature. This third positioning feature can in particular be in the form of two cylindrical elements, and the second positioning feature can be in the form of a tongue and / or hook extending between the two cylindrical elements and having a lower contact surface adjacent to the cross piece of the first positioning feature. The cylindrical elements do not come into contact with this lower contact surface, but each cylindrical element usually comes into contact with the side surface of the second positioning feature. The cylindrical elements preferably have a certain flexibility, because of this, and because the cylindrical elements are not connected by a cross piece (as the side legs of the first positioning feature), it is possible to prevent large clamping forces between the cylindrical elements of the second and third positioning features. Such high clamping forces are not required as they would counteract the effect of axial positioning and would also prevent the module from being easily pressed down to activate the horn. With this arrangement, good centering of the airbag module on the steering wheel body is achieved.

[0013] 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 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.

[0014] The present invention will now be described in more detail using preferred embodiments according to the accompanying drawings. The accompanying drawings show:

[0015] Figure 1: a strongly schematic cross-sectional representation of all relevant elements of a first embodiment of the inventive steering wheel,

[0016] Figure 2 :Depend on Figure 1 The components shown form a subassembly of an airbag module,

[0017] Figure 3 :according to Figure 2 The complete airbag module in the representation,

[0018] Figure 4 : In fully assembled state Figure 1 All components shown,

[0019] Figure 5 :from Figure 1 The direction R1 is observed Figure 1 Bottom view of the cover,

[0020] Figure 6 :from Figure 1 The direction R2 is observed Figure 1 A bottom view of the housing element is shown,

[0021] Figure 7 :from Figure 1 The direction R3 is observed Figure 1 Bottom view of the locking plate shown,

[0022] Figure 8 :from Figure 1 The direction of R4 is observed Figure 1 The plan view of the skeleton shown,

[0023] Fig. 9 :from Figure 1 The direction of R5 is observed Figure 1 A side view of the first and third locating features of the housing element is shown,

[0024] Fig.10 :from Figure 1 The direction of R6 is observed Figure 1 View of the hook of the housing element,

[0025] Fig.11 : A detailed perspective view of a complete steering wheel according to a second embodiment of the invention,

[0026] Fig.12 : Observed from above Fig.11 Plan view of the steering wheel,

[0027] Fig.13 :along Fig.12 The cross-sectional view taken by plane AA in

[0028] Fig.14 : A perspective view of a locking plate of a second embodiment,

[0029] Fig.15 :according to Figure 4 The third embodiment of the present invention is represented by

[0030] Fig.16 : Fig.15 but using a more detailed perspective,

[0031] Fig.17 : the first and second locating features in another embodiment,

[0032] Fig.17a :from Fig.17 The direction R7 observed Fig.17 A side view of the first locating feature, but schematically, and

[0033] Fig.18 : The first and second positioning features in another embodiment.

[0034] 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.

[0035] Figure 1 The 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.

[0036] 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:

[0037] As just mentioned, Figure 1 and Figure 52 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.

[0038] 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.

[0039] 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.

[0040] 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:

[0041] 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.

[0042] 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.

[0043] In the embodiment shown, the housing element 30 also includes two cylindrical members 48 located between the side legs 46 of the first positioning feature 42; these cylindrical members 48 form a third positioning feature. The cylindrical members 48 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.

[0044] 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.

[0045] 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.

[0046] 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. This 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 / 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. This distance D2 is equal to or almost equal to the distance D1 between the two columnar pieces of the third positioning feature.

[0047] Figure 2A 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.

[0048] 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.

[0049] Figure 4 The 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.

[0050] 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.

[0051] 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.

[0052] Fig.15 and Fig.16An 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.

[0053] Fig.17 and Fig.18 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 towards the module distal end, while their thickness (in the radial direction) increases, so that the cross-sectional area remains essentially 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. Due to the presence of the limiting feature, the enhanced flexibility does not increase the risk of breakage. If desired, this type of design can be combined with the presence of a third locating feature.

[0054] Reference numerals list

[0055] 5. Steering Wheel

[0056] 10 Airbag module

[0057] 20 Cover

[0058] 22 Top of cover

[0059] 24 Cover side wall

[0060] 26 snap hook (snap feature)

[0061] 30 Shell element

[0062] 31 Shell section

[0063] 32 Shell bottom plate

[0064] 34 Shell side wall

[0065] 36 Holes for snap hooks on cover

[0066] 37 Holes for inflator

[0067] 38 Holes for attaching locking plate

[0068] 39 Protrusion for coil spring

[0069] 40a First hook (first mounting feature)

[0070] 40b Second hook (second mounting feature)

[0071] 42 U-shaped first positioning feature

[0072] 44 Horizontal piece

[0073] 46 Side Leg

[0074] 46a First section (module side section)

[0075] 46b Middle section

[0076] 46c Second section (lateral section)

[0077] 48 Third positioning feature (column between side legs)

[0078] 49 Housing element / protrusion of limiting feature

[0079] 50 Locking plate

[0080] 52 protrusion (bend section / limiting feature)

[0081] 53 Bay

[0082] 54 holes for inflator

[0083] 56 Attachment holes

[0084] 58 Hole for protrusion 39

[0085] 60 Coil Spring

[0086] 70 Steering wheel frame (part of the steering wheel body)

[0087] 72 Hole for hook (part of the third and fourth mounting features)

[0088] 74 Mounting spring (part of the third and fourth mounting features)

[0089] 76 second positioning feature

[0090] 76a Lower contact surface

[0091] 76b, 76c side surfaces

[0092] 78 Protrusion for coil spring

[0093] 80 Spokes (part of the steering wheel body)

[0094] 82 Rim (part of the steering wheel body)

[0095] 90 Airbag Cushion

[0096] 95 Inflator

[0097] C Center Line

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) attached to the housing section (31) by snap features (26), and - 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 The airbag module (10) further includes a locking plate (50) for locking the snap feature (26) of the cover (20), and The airbag module (10) 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).

2. The steering wheel according to claim 1, characterized in that: The restraining feature is in the form of at least one protrusion (52) of the locking plate (50).

3. The steering wheel unit according to claim 1, characterized in that The restriction feature is in the form of at least one protrusion (49) of the housing element (30).

4. Steering wheel according to one of the preceding claims, 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 (76).

5. The steering wheel according to claim 4, characterized in that: The third locating feature is in the form of two pillars (48), and the second locating feature (76) extends between the two pillars (48).

6. 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.

7. The steering wheel according to claim 6, 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.

8. The steering wheel according to claim 7, 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.

9. 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.

10. The steering wheel unit according to claim 9, 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.

11. 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.

12. An airbag module (10) adapted to be part of a steering wheel according to any one of claims 1 to 11 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) attached to the housing section (31) by snap features (26), and - 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, It is characterized in that The airbag module (10) further includes a locking plate (50) for locking the snap feature (26) of the cover (20), and The airbag module (10) 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).

Images