Abstract:
A housing for a passenger protection device in a motor vehicle having an airbag and a gas generator therein and a protective covering thereon to form a ready to install module. The housing comprises a body having an essentially U-shaped cross section which is uniform lengthwise along an axis. The housing also has two mainly flat end covers and tension members for simultaneously fastening the airbag and the protective covering to the housing.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a housing to accommodate a gas generator and an airbag for a passenger protection system in a motor vehicle, which, together with the gas generator, the airbag and in some cases a protective covering, a lid and fastening means, forms a module ready for installation. 
     SUMMARY OF THE INVENTION 
     To an increasing extent, automobile manufacturers are offering airbags for the passenger as extra equipment, or even as standard equipment. Their aim is to manufacture such airbag modules as inexpensively as possible in order to be able to offer the customer the additional safety at the lowest possible cost. All elements of the airbag module are critically analyzed and examined for possible cost savings. In the case of a housing, savings can be achieved especially by not only adapting it to the existing, sometimes narrow and angular installation conditions, but vice-versa by configuring the areas of the motor vehicle body, especially the instrument panel, for the installation of an airbag. In this manner the possibility is created for designing a single housing for a plurality of applications and for exploiting the manufacturing advantages for the production of large numbers of units. 
     The invention is addressed to the problem of proposing a housing of the kind referred to above, which will be simple and cheap to manufacture while taking into consideration the criteria given above, and which will be as light as possible without the need to accept functional disadvantages. 
     For the solution of this problem, it is proposed according to the invention that the housing be composed of a substantially U-shaped body and two mainly flat end covers, the body having a uniform cross section along its length, the end covers being connected to the body by tension means disposed in the direction of the axis of the base, and the tension means serving simultaneously for fastening the airbag and, in some cases, a protective covering or a lid. 
     To manufacture the body for such housings it is best to start out with a specially shaped stock material from which sections are separated by cuts made perpendicular to its long axis. 
     The body can be made from a sheet-metal stock or an extruded stock. In all cases the starting product is a comparatively simple and very easily made cross-sectional profile which, of course, is suited to the requirements of an airbag housing. 
     If one starts with a sheet-metal stock, the latter can be produced somewhat similarly to a roof gutter, i.e., with a U-shaped cross section with a semicircular bottom. The upper edges are best rolled outwardly and each of the vertical walls has semicircular indentations at a distance from the rolled edge but above the transition into the semicircular bottom. 
     The indentations are of such dimensions that the tension means placed in them will be approximately flush with the exterior of the side walls. 
     In such a body consisting of a stock material, the corresponding end covers are advantageously made of flat sheet-metal parts matched to the cross section of the base, and their margins are bent at approximately right angles to overlap the body. In one advantageous embodiment, the end covers have, in a known manner, the openings required for the installation of the generator, and four marginal bores to receive tension means in the form of tension rods provided with threaded ends. For the fastening of the airbag and/or the protective coverings to the housing, it is expedient to use sections of the material of the airbag or protective covering which can be slung around the tension rods and clamped between the tension rods and the base. 
     In another embodiment, the stock material again has a U-shaped cross section with a semicircular bottom, but the upper edges are folded outward to a greater width forming a doubled margin and the vertical walls are offset outwardly over about half their length, and in the area of the doubled margin, openings running longitudinally are provided. For this embodiment the tension means consist of two internal stringers of a substantially T-shaped cross section running over the entire length of the body, two external channel-shaped sections also extending over the entire length of the body and provided with openings corresponding to those in the body, plus two tension anchors which can be passed through the end covers. At the same time the base of the T-shaped stringers has a longitudinal slot to accommodate the tension rod and extends longitudinally only over the areas in which openings are provided in the body in the doubled margin. Sections of the material of the airbag and/or covering can be gripped over the entire length of the body by the tension armature between the outside U-shaped stringer and the body. In this case the inside T-shaped stringer can consist of a bent sheet metal blank in which the base limb is of a double-walled U shape and the areas of the base limb which do not correspond to the openings in the body are cut out. The outside U-shaped stringer can also consist of a bent sheet metal blank in which the openings are punched. 
     In a further embodiment, provision is made: for the extruded stock material to have a substantially U-shaped cross section with a semicircular bottom; for an intermediate wall to be provided, roofing over the bottom area approximately semicircularly and provided with openings; for the vertical sides to have a step-like, half-height offset, and for the ends of the U-shaped cross section to form outwardly facing, closed annular chambers in the walls of which inside openings extending longitudinally are provided. In this case the tension means consist of two inside, T-shaped stringers and two tension anchors, the base portion of the stringer having a longitudinal bore to receive the tension armature and extending longitudinally only over the areas in which openings are provided in the wall of the annular chamber. 
     Alternatively, in the body consisting of an extruded blank, the vertical walls have sections protruding outward at right angles approximately at one-half their height, which form closed, elongated annular chambers lying above these sections, in the walls of which openings extending lengthwise are provided. In this case the tension means consist of two external, T-shaped stringers and two tension anchors, the base part of the stringer having a longitudinal bore to receive the tension anchor and extending longitudinally only over the areas in which openings are provided in the wall of the annular chamber. In the two last-mentioned embodiments, sections the material of the airbag and lid can be clamped together between the T-shaped stem and the upper area of the body. Another advantageous variant of the invention is that the clamped portion of the material of the lid has an inside or outside dog-leg cross section by means of which the doubled material of the base portion or of the T-shaped stringer can be positively gripped. 
     Furthermore, provision is made such that the T-shaped stringers can consist of an extruded stock material. Instead of the two tension anchors running all the way through, four bolts with self-tapping threads can be provided. A further simplification can be that the T-shaped stringers are made integral with one of the end covers. Lastly, it is expedient for the end covers have means for fastening the module in an instrument panel or in a vehicle body. 
     Thus a variety of embodiments of the fundamental idea of the invention have been described, which satisfy all of the requirements stated in the beginning. The body parts consist in each case of sections cut from a stock material that can be made in great lengths and hence economically, and their cross-sectional shape can be adapted to the requirements in many different ways. Together with the end covers and the tension means running lengthwise of the body, housings consisting of few component parts, which can be assembled by the tension means with the airbag, the gas generator and, if desired, a protective covering or a lid, to form an airbag module. It is seen to be especially advantageous that the tension means were able to be reduced to four tension anchors or four bolts, and that no further fastening means are necessary for fastening the airbag, the protective cover and the lid. If additional mounting hardware is needed for fastening the airbag module to the body of the vehicle, it can also be fastened to the airbag module with the tension means. 
     Additional details will be given with the aid of the embodiments represented in FIGS. 1-5. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a first embodiment in section 
     FIG. 2 the first embodiment in a side view 
     FIG. 3 a second embodiment in section 
     FIG. 4 a third embodiment in section 
     FIG. 5 a fourth embodiment in section. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a housing 1 for an airbag module in which the base member 2 consists of a section made by cutting through a sheet-metal blank perpendicularly to its length. The cross-sectional shape is essentially U-shaped with a semicircular-shaped bottom portion and with sides 10 which are rolled outwardly at the top edges 9. Furthermore, two indentations 11, 12 are provided in the sides 10, and they are of approximately semicircular shape and serve to receive the tension means, consisting of tension rods 4, when the airbag module is in place. The end cover 3 has an opening 15 to accommodate a gas generator. Above this opening the airbag 6 is folded and provided with a protective covering 7. Both the airbag and the protective covering are provided with sections 17, 18 of material which can be slung around the tension rods 4. 
     It can be seen from the side view of this housing 1 in FIG. 2 how the end covers 3 have margins 13 bent away at right angles to overlap the body member 2. In the left end cover 3 an opening 14 is provided which serves for the fastening of the gas generator 16. The tension means consist in this case of the tension rods 4 which have threaded ends and the nuts 5 which are threaded onto the tension rods. 
     In the embodiment in FIG. 3, the body 2a again consists of a section of a prepared sheet-metal stock of essentially U-shaped cross section, whose upper margins are folded outwardly over a greater width to form a doubled margin 19. The vertical walls 20 are offset outwardly at half their height and at the doubled margins openings 21 running lengthwise are provided. In this case the clamping means consist of two essentially tee-like members 22 extending on the inside over the entire length of the body 2a, plus two exterior channel-shaped members 24 also extending over the entire length of the body and provided with openings 23 corresponding to those provided in the body 2a, plus two tension anchors 25 which can be passed through the end covers 3. Portion 26 of the T-shaped stringers 22 contains a core 27 to receive the tension anchors and extends longitudinally only over the areas in which openings 21 are provided in the area of the doubled margins 19 in the body 2a. Portions of the material of the airbag 28 and/or of a lid 8 are clamped over the entire length of the body 2a between the outside channel members 24 and the body 2a. At the same time the elasticity of the clamped material sections 28, 29 and of the clamping members 22, 24 and tension anchors 25 is utilized for the purpose of producing sufficient tension in the clamping area over the entire length of the body 2a. 
     In the embodiment in FIG. 4 the body 2b consists of an extruded stock material with, again, an essentially U-shaped cross section with a semicircular bottom 30. Furthermore, there is provided a dividing wall 31 overarching the bottom and provided with openings 32. The vertical walls 33 have a step-like offset 34 at about half their height, and the ends 35 of the U-shaped cross section form outwardly closed chambers 36. Longitudinal openings 37 are made on the inner side of the latter. In this embodiment the tension means consist of two inside tee-like members 38 and two tension anchors 39, the stem part 40 of the tee 38 having a longitudinal bore 41 to receive the tension anchor 39 and extending longitudinally only over the area in which openings are provided in the wall of the ring chamber 36. Portions 48 of the material of the airbag and portions 49 of the lid 8 are clamped between the tee-like members 38 and the wall of the body 2b, while the bottom ends of the material sections 49 are hooked behind the tee-like members 38 with a portion 50. 
     The embodiment in FIG. 5 likewise consists of a section of extruded stock material, while the bottom portion of the body 2c is configured as in the embodiment shown in FIG. 4. The vertical walls 33 have at about half their height outwardly reaching sections 42, and the wall portions above these sections form closed, tube-like chambers 43 in whose outside walls slots 44 extending lengthwise are made. The tension means consist of two outside flanges 45 and two tension anchors 46, the stem portion of the flanges 45 having a longitudinal bore 47 to receive the tension anchor 46 and extending longitudinally only over the portions in which the slots 44 are provided in the wall of the annular chamber. Sections of material 48, 49 of the airbag and lid 8 are clamped together by the tension anchor between the flanges 45 and the upper part of the body 2c. The clamped section 49 of the lid 8 has at its end an outwardly offset rim 50 which can fit below the flanges 45. The section 49 of the material of the lid 8 can also be made bipartite, in which case the outside part 49 and an inside part 52 are combined integrally by a loop of material 51, and between them they clamp the section of the material 48 of the airbag when the latter is installed. In this case too the elasticity of the material is utilized to produce sufficient bias acting over the entire clamped area.