WO2013070905A1

WO2013070905A1 - Snap in driver side airbag module assembly

Info

Publication number: WO2013070905A1
Application number: PCT/US2012/064137
Authority: WO
Inventors: Valerio Poli; Bruno Alessio; Adolfo Ridolfi
Original assignee: Key Safety Systems Inc.
Priority date: 2011-11-09
Filing date: 2012-11-08
Publication date: 2013-05-16

Abstract

A DAB module assembly (10) for attachment to a steering wheel armature (20) has a housing (12) for storing an airbag cushion and a leaf spring (2). The housing (12) has a plurality of guides (18) positioned on the housing (12) spaced from an axial center of the housing (12). The leaf spring (2) has a three point attachment wherein the leaf spring (2) is attached in two locations (5) on a lower portion of the housing (12), and a third attachment location of the leaf spring (2) separate of the housing is spaced from a housing bottom (13) and has an aperture (3) for fitting onto a projection (22) fixed on the armature.

Description

SNAP IN DRIVER SIDE AIRBAG MODULE ASSEMBLY

Field of the Invention

[001] The present invention relates to a Driver Side Airbag (DAB) module assembly with improved attachment features to a steering wheel armature, more particularly to a snap-in attachment of the module to the armature.

Background of the Invention

[002] Driver side airbag modules are designed to be attached to a center portion of a steering wheel. The center portion is called the armature. Extending from the armature are usually two or more spokes which are attached to a circular rim. The rigid portion of this steering wheel is often referred to as the skeleton. Often the rim and spokes are encapsulated with a foam having an outer skin of vinyl simulating leather or covered in leather. Optional wood or wood simulation can adorn the steering wheel. Typically incorporated into these steering wheels can be a variety of devices or switches that operate the cruise control or the horn or the radio to name a few. Centered in the steering wheel is situated the airbag module for protecting the driver of the vehicle.

[003] This driver side airbag module assembly is securely attached to the armature of the steering wheel. It is often referred to as the DAB module assembly and it includes an inflator and an airbag cushion housed inside a module housing which has an outer cover concealing the cushion attached to the housing. This outer cover often has a frangible tear seam that allows the inflating airbag to break the seam and deploy upon inflation. Often the entire airbag assembly includes or overlays one or more horn activation switches. To sound the horn, the driver pushes on the cover of the DAB module and the entire DAB assembly is moved inwardly closing the contacts of the underlying horn activation switches causing the horn to blow or sound.

[004] To assemble the DAB module assembly to a steering wheel has been at best a challenge. Ideally, to insure a secure attachment that is reliable and rather simple to achieve, manufacturers have strived to develop snap-in driver side airbag modules. The goal has been to connect the airbag module electrically and then snap the entire assembly into locking engagement with the steering wheel. Once attached, these devices generally require special tools to unlatch and replace the module as may be required to replace it once deployed or in case it becomes inoperable.

[005] A large challenge in the use of snap-in modules is to have the cover equally spaced on assembly such that the gap along the edges of the cover and the steering wheel are substantially equal. If the module snaps into position and the gaps are unequal, this is readily noticeable and very unappealing. On horn activated DAB modules, the problem can occur as the driver activates the horn so even if the module is centered on assembly it can be shifted by sounding the horn. To overcome this, airbag modules have been made with complex designs to limit lateral movement. In US 7,398,994 B2 "A Snap-In Assembly For Retaining An Airbag Module To A Steering Wheel" discloses a retaining assembly to drive an airbag module that is moveable linearly exclusively along a path parallel to the axis of rotation of the steering wheel while providing constant horn activation loads. This retention assembly is a masterful design which limits the movement of the module exclusively in a linear direction regardless of the location on which the driver presses on the airbag cover. This prior art design while very effective requires a complex design.

[006] It is an object of the present invention to provide a similar exclusively linear movement in a snap-in DAB module assembly, but with a much simpler design. It is a further objective of the present invention to insure gap control is uniform and

consistently maintained between the cover and the steering wheel upon assembly and through numerous horn activations.

[007] These and other beneficial objectives are achieved by the present invention as described herein.

Summary of the Invention

[008] A DAB module assembly 10 for attachment to a steering wheel armature 20 has a housing 12 for storing an airbag cushion and a leaf spring 2. The housing 12 has a plurality of guides 18 positioned on the housing 12 spaced from an axial center of the housing 12. The leaf spring 2 has a three point attachment wherein the leaf spring 2 is attached in two locations 5 on a lower portion of the housing 12, and a third attachment location of the leaf spring 2 separate of the housing is spaced from a housing bottom 13 and has an aperture 3 for fitting onto a projection 22 fixed on the armature. Each guide 18, on initial assembly of the DAB module assembly to the armature20, first aligns with receiving sleeves 26 fixed on the armature 20 limiting movement of the DAB module assembly 10 in a linear direction. Subsequently on further moving, the aperture 3 in the leaf spring 2 fits over the projection 22 fixed on the armature 20 constraining movement of the DAB module assembly 10 to an axial direction parallel to the rotational axis of the steering wheel armature as the leaf spring 2 deflects until the DAB module assembly 10 comes into locking engagement to the armature.

[009] In a preferred embodiment, the leaf spring 2 is "V" shaped.

[0010] The "V" shaped leaf spring 2 is attached in two locations on the lower portion of the housing 12 and an apex of the "V" shaped leaf spring 2 has the aperture 3 for fitting on the projection 22 of the armature. Preferably, the DAB module assembly 10 for attachment to a steering wheel armature 20 further has two or more retaining wires 15. The retaining wires 15 extend into locking engagement with two or more corresponding attachment locations or hooks 24 on the armature. The retaining wires 15 are "U" shaped and extend along the housing and are oriented generally parallel to an axial direction. The closed ends of the "U" shape retaining wires 15 deflect laterally to pass over attachment locations or hooks 24 on the armature 20 as the DAB module assembly 10 comes into locking engagement with the armature 20. The DAB module assembly 10 snaps onto the steering wheel armature 20 causing the leaf spring 2 to deflect on assembly biasing the DAB module assembly 10 outwardly in the attached position. The DAB module assembly is constrained to a linear movement and to sound a horn the leaf spring 2 deflects upon pushing the DAB module assembly 10 to activate or close a horn switch.

[0011] The DAB module assembly 10 for attachment to a steering wheel armature 20 may optionally include an armature bracket, the armature bracket being attached to the armature 20 and wherein the DAB module assembly 10 snaps into the armature bracket on assembly 10. The armature bracket can have all the attachment features for securing the DAB module assembly. Alternatively, the DAB module assembly 10 for attachment to a steering wheel armature 20 the DAB module assembly 10 can snap directly into a steering wheel armature 20 with the attachment feature being an integral part of the armature. [0012] The DAB module assembly 10 for attachment to a steering wheel armature 20 preferably further has a cover 14 fixed to the housing 12. The cover 14 has two or more extending attachment ears 16. The attachment ears 16 extend outwardly and deflect on the assembly of the DAB module assembly 10 snapping to the armature 20 under corresponding undercuts 26 on the armature 20 to center and locate the cover 14 into the steering wheel. The attachment ears 16 has a spring like characteristic and are capable of deflecting or bending as the cover 14 is pushed inwardly during horn activation.

[0013] The armature 20 has a base structure 23 and a plurality of hooks. The base structure 23 has a projection 22 for aligning the DAB module assembly 10 and the plurality of hooks 24 are used as attachment locations on the armature 20 for securing the housing 12 of the DAB module assembly 10.

[0014] The combination of a DAB module assembly 10 and steering wheel armature 20 has a DAB module assembly 10 and an armature.

[0015] The DAB module assembly 10 has a housing 12 for storing an airbag cushion, the housing 12 having a plurality of guides 18 on the housing 12 spaced from an axial center of the housing 12 and a leaf spring 2 having a three point attachment wherein the leaf spring 2 is attached in two locations 5 on a lower portion of the housing 12, and a third attachment location of the leaf spring 2 is spaced from the housing and has an aperture 3 for fitting onto a projection 22 fixed on the armature 20. Each guide 18 on initial assembly first aligns with receiving sleeves 26 fixed on the armature 20 limiting movement of the DAB module assembly 10 in a linear direction and subsequently moving the aperture 3 in the leaf spring 2 over the projection 22 of the armature 20 constraining movement of the DAB module assembly 10 to the axial direction as the leaf spring 2 deflects until the DAB module assembly 10 comes into locking engagement to the armature 20. The armature 20 has a base structure 23, the base structure 23 having a projection 22 for aligning the DAB module assembly 10 and a plurality of hooks 24 for securing the DAB module assembly 10.

Brief Description of the Drawings

[0016] The invention will be described by way of example and with reference to the accompanying drawings in which: FIG. 1 is a perspective view of the DAB module assembly of the present invention.

FIG. 2 is a side view of the DAB module assembly and a cutaway view of the steering wheel armature prior to assembly illustrating the guides and leaf spring orientation before attachment.

FIG. 3 is a second side view similar to figure 2 but from a perspective rotated approximately 90 degrees to show the aperture of the leaf spring and the projection fixed on the armature prior to assembly.

FIG. 4 is a view taken from figure 3 wherein the DAB module assembly is shown attached to the armature.

Detailed Description of the Invention

[0017] With reference to figure 1, an upward looking perspective view of the driver side airbag module assembly 10 of the present invention with multiple attachment features for attachment to a steering wheel is shown. The driver side airbag module assembly 10 hereinafter referred to as the DAB module assembly provides a clever unique

combination of features that allow the inventive DAB module assembly 10 to be quickly and easily automatically attached to a steering wheel by a simple snap-in attachment.

[0018] The DAB module assembly 10 has a plurality of guides 18 positioned onto the sides or bottom of the module housing 12. The housing 12 internally stores the airbag cushion (not illustrated) under a cover 14 which is attached to the housing 12. The guides 18 project downwardly a distance sufficient to be the first elements to engage the steering wheel armature 20. This is more clearly visible in figure 2 when the guides 18 are shown directly above the receiving sleeves 26. The receiving sleeves 26 have openings 29 for receiving the guides 18. The guides 18 are spaced on the peripheral sides of the housing spaced from a central axis of the steering wheel armature 20. As the guides 18 enter the receiving sleeve 26 the DAB module assembly 10 is aligned. As shown, the guides 18 have a rounded curvature or radius 17 at an end 19 and the receiving sleeve 26 has a shallow chamfer 27. The features facilitate getting the guides 18 to align and fit into the opening 29. At this stage of assembly the DAB module assembly 10 is aligned at three points constraining the movement of the DAB. At this stage of the assembly, the guides 18 provide a limited constraint in the xy plane or horizontal plane wherein the DAB can shift rotationally only a small amount, but can be tilted in a Z or vertical direction binding the DAB module assembly 10 in the armature 20. The guides 18 and opening 29 have a clearance fit so they can slide easily up and down in a Z or vertical direction. These clearances would otherwise enable the DAB module assembly 10 to rest on assembly not properly centered about the axis of rotation R of the armature 20 if the guides 18 were the only alignment feature. This is important because on each movement of the DAB inwardly to activate a horn switch, the DAB could move to any other position which means the cover 14 could never really be centered.

[0019] With reference to figures 3 and 4, on assembly as the DAB module assembly 10 is moved further inwardly several additional attachment features are engaged further constraining the assembly 10 insuring a very precise alignment of the DAB module assembly 10 to the armature 20.

[0020] One set of at least two "U" shaped wire attachments 15 is shown extending from the housing 12 and as the DAB module assembly 10 moves inwardly these wire attachments 15 each engage a hook 24 fixed on the armature bottom 23 as shown the hook 24 is integral to the armature 20, but it alternatively could be a separate bottom bracket which is rigidly fixed to the armature 20. The hook 24 is elongated in shape vertically and as the wire attachment 15 contacts the hook 24 it slides on the hook 24 outer surface deflecting laterally outwardly until the wire attachment 15 snaps inwardly under the hook 24 locking the wire 15 in place. The armature 20 has an opening 24A which allows the wire attachment 15 to pass sliding over the surface of the hook 24.

[0021] With further reference to figures 3 and 4, a very important alignment feature is simultaneously being engaged as the DAB module assembly 10 is being snapped into place onto the armature 20. This alignment feature is a leaf spring 2. The leaf spring 2 is attached at two attachment locations 5 offset from the center of the housing 12 and attached on the side or bottom 13 of the housing 12. The leaf spring 2 extends inwardly and under the bottom 13 of the housing 12, but spaced a vertical distance S inwardly or vertically from the bottom 13. As shown, the leaf spring 2 is inclined away from the DAB module assembly 10. As further shown the leaf spring 2 has an aperture 3 that aligns with a projection or pin 22. As shown, the projection or pin 22 has a conical end 22A which upon assembly fits into the aperture 3. In figure 3 this spaced alignment is shown and in figure 4 the mating of the aperture 3 and projection 22 are shown aligned and joined. As shown, the aperture 3 fits tightly onto the projection 22, preferably the aperture 3 has an internal surface to fit onto the conical end 22A with no clearance. This insures that once the leaf spring 2 deflects onto the projection 22, the ability of the DAB module assembly 10 to move is constrained to only a linear movement parallel to the axis R of the armature 20. As must be recalled, the guide 18 initially only had three points of alignment with a clearance gap and as the DAB module assembly 10 moved inwardly the leaf spring 2 deflects and the aperture 3 provides another constraint that is in a deeper vertical plane with no clearance. The combination of the guides 18 in an upper plane with the leaf spring aperture 3 fitting onto the projection 22 further limits the DAB module assembly 10 to vertical movements and the alignment of the cover 14 is greatly improved. As shown when the leaf spring 2 is fully deflected the wire attachment 15 were allowed to snap over the hooks 24. Furthermore, the use of a deflected leaf spring 2 means the entire DAB module assembly 10 is biased by a spring force outwardly when not being depressed to activate a horn switch. Accordingly, the entire assembly 10 is easily attached to the armature 20 with a simple pushing of the assembly 10 onto the armature securing an automatic self-aligning snap fit.

[0022] As further shown in figures 3 and 4, the cover 14 further includes a plurality of attachment ears 16 extending from the sides under an exterior surface of the cover 14. These ears 16 are bendable and deflect such that as the DAB module assembly 10 is being snapped into place, the ears 16 deflect and slide and lock into and under corresponding undercuts 28 in the armature 20. The ears 16 being able to deflect do not limit the vertical movement of the DAB module assembly for horn activation, but because the ears 16 are preferably in three or more locations on the cover 14 they insure the cover 14 is always being additionally centered by a spring loaded biasing force created by the ears 16 pushing against the undercuts 28.

[0023] As can be appreciated, the combination of the guides 18, the leaf spring 2 and the wires 15 and ears 16 all insure the device can be automatically aligned and centered simply upon the snap-in attachment. No additional steps or fitment adjustments are required. If the two parts, the DAB module assembly 10 and the armature 20 are snapped together they are automatically properly aligned.

[0024] As shown in the figures, the leaf spring 2 preferably has two fixed attachment locations 5 on the housing 12 and one aperture 3 location for fitting the aperture 3. This three point attachment is ideally suited to making the leaf spring 2 in the "V" shaped configuration as shown. While the leaf spring 2 is not limited to this shape it is preferred in that the apex of the "V" shaped leaf spring 2 is an ideal location for the aperture 3 and the ends of legs of the "V" make easy fixed attachment locations 5 as illustrated. Ideally the leaf spring 2 is made of spring steel to enable repeated deflections.

[0025] In order to obtain a good module 10 to steering wheel 20 fit matching, the module movement during the horn system operating has to be ideally axial, without rollings or teetering that cause lateral movement that have to be compensated for by increasing the gap between the module 10 and steering wheel 20, as currently happens in all the current systems. In this invention, the axial movement is obtained by a parallelogram or double pendulum constraint achieved by the combination of features. In the DAB bottom 13 there is an elastic steel lamina or leaf spring 2 having a "V" shape with two extremities fixed in the DAB bottom 13 and one hinged to the armature 20. This lamina 2 stops the translations in a frontal plane and gives the reaction to the horn activation. In the DAB top, at least two elastic opposed ears 16 obtained by the cover 14 engage steering wheel undercuts 28 or pockets. This stops the translations in a frontal plane higher than that of the lamina or leaf spring 2. This results in the addition of the constraint in the bottom (one connecting-rod) and ideally admits only the translation in the column axis. In this condition, there is enough stroke to make an electrical contact in a microswitch or other switch. To protect the kinematics and insure the contact there is a constant outward spring force pushing the assembly 10 into a non activated condition.

[0026] Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.

Claims

CLAIMS What is claimed is:

1. A DAB module assembly 10 for attachment to a steering wheel armature 20 comprises:

a housing 12 for storing an airbag cushion, the housing 12 having a plurality of guides 18 on the housing 12 spaced from an axial center of the housing 12;

a leaf spring 2 having a three point attachment wherein the leaf spring 2 is attached in two locations 5 on a lower portion of the housing 12, and a third attachment of the leaf spring 2 is spaced from a housing bottom 13 and has an aperture 3 for fitting onto a projection 22 fixed on the armature; and

wherein each guide 18 on initial assembly first aligns with receiving sleeves fixed on the armature 20 limiting movement of the DAB module assembly 10 in a linear direction and subsequently moving the aperture 3 in the leaf spring 2 over the projection 22 fixed on the armature 20 constraining movement of the DAB module assembly 10 to the axial direction as the leaf spring 2 deflects until the DAB module assembly 10 comes into locking engagement to the armature.

2. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 1 wherein the leaf spring 2 is "V" shaped.

3. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 2 wherein the "V" shaped leaf spring 2 is attached in two locations on the lower portion of the housing 12 and an apex of the "V" shaped leaf spring 2 has the aperture 3 for fitting on the projection 22 fixed to the armature.

4. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 1 comprises two or more retaining wires 15, the retaining wires 15 extend into locking engagement with two or more corresponding attachment locations 24 on the armature.

5. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 4 wherein the retaining wires 15 are "U" shaped.

6. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 5 wherein the "U" shape retaining wires 15 deflect laterally to pass over attachment locations 24 on the armature 20 as the DAB module assembly 10 comes into locking engagement with the armature 20.

7. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 1 wherein the leaf spring 2 is deflected on assembly biasing the DAB module assembly 10 outwardly in the attached position.

8. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 7 wherein the leaf spring 2 deflects upon pushing the DAB module assembly 10 to activate a horn switch.

9. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 1 wherein the DAB module assembly 10 includes an armature bracket, the armature bracket being attached to the armature 20 and wherein the DAB module assembly 10 snaps into the armature bracket on assembly 10.

10. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 1 wherein the DAB module assembly 10 snaps directly into a steering wheel armature 20.

11. The DAB module assembly 10 for attachment to a steering wheel armature 20 of claim 1 comprises a cover 14 fixed to the housing 12, the cover 14 having two or more extending attachment ears 16, the attachment ears 16 extend outwardly and deflect on the assembly of the DAB module assembly 10 snapping to the armature 20 under corresponding undercuts 26 on the armature 20 to center and locate the cover 14 into the steering wheel, the attachment ears 16 being capable of deflecting or bending as the cover 14 is pushed inwardly during horn activation.

12. An armature 20 for attaching the DAB module assembly 10 of claim 1, the armature 20 comprising:

a base structure 23, the base structure 23 having a projection 22 for aligning the DAB module assembly 10; and

a plurality of hooks 24 used as attachment locations on the armature 20 for securing the housing 12 of the DAB module assembly 10.

13. The combination of a DAB module assembly 10 and steering wheel armature 20 comprising:

a DAB module assembly 10 comprising a housing 12 for storing an airbag cushion, the housing 12 having a plurality of guides 18 on the housing 12 spaced from an axial center of the housing 12 ;

a leaf spring 2 having a three point attachment wherein the leaf spring 2 is attached in two locations 5 on a lower portion of the housing 12, and a third attachment of the leaf spring 2 is spaced from a housing bottom 13 and has an aperture 3 for fitting onto a projection 22 fixed on the armature 20;

wherein each guide 18 on initial assembly first aligns with receiving sleeves 26 fixed on the armature 20 limiting movement of the DAB module assembly 10 in a linear direction and subsequently moving the aperture 3 in the leaf spring 2 over the projection 22 fixed on the armature 20 constraining movement of the DAB module assembly 10 to the axial direction as the leaf spring 2 deflects until the DAB module assembly 10 comes into locking engagement to the armature 20;

an armature 20 comprising a base structure 23, the base structure 23 having a projection 22 for aligning the DAB module assembly 10; and

a plurality of hooks 24 for securing the DAB module assembly 10.