Abstract:
A connecting line is intended to connect a gas bag for a gas bag-type occupant protection system with a gas generator. The connecting line includes a gas exit section intended to be arranged within a gas bag and having outer surface area. The gas exit section is provided with at least one gas exit port. The gas exit port has at least one gas guidance surface area which extends from the outer surface area of the gas exit section into the interior of the gas exit section of the said connecting line with a predetermined depth.

Description:
The invention relates to a connecting line for a gas bag-type occupant protection system. 
     BACKGROUND OF THE INVENTION 
     Connecting lines for gas bag systems are provided for inflating a gas bag with compressed gas and comprise a gas exit section extending into the gas bag, this gas exit section being provided with at least one gas exit port. 
     Gas bag-type occupant protection systems serve, for example, to protect the heads of vehicle occupants in case of a side impact collision. For this purpose a gas bag is deployed between the side windows and the head of the vehicle occupant in case of a collision. The gas bag is generally inflated by an inflator arranged on the C-pillar of the vehicle, this inflator being connected to the gas bag by a connecting line of the aforementioned kind. For the gas bag extending along the side windows of the vehicle to be able to be inflated uniformly the connecting line comprises a gas exit section extending by a considerable length into the gas bag. This gas exit section is also termed a gas lance and is provided with a plurality of gas exit ports. Due to this arrangement gas emerges over a considerable length of the gas bag which, depending on the type of vehicle involved, may amount to, for example, approximately 1.2 m, and the gas bag is uniformly inflated. The gas exit ports are usually formed by milled slots, roughly two to four such slots being provided within the gas bag. Since the gas on deployment of the gas bag flows within the gas lance at a very high velocity extending into the supersonic range, the slots must be of considerable length so that a sufficient amount of gas is able to exit laterally from the gas lance. Accordingly, milling these slots is time-consuming and expensive. In addition to this the milled gas exit ports weaken the structure of the gas lance and are difficult to deburr. 
     It is the object of the invention to simplify the manufacturing of the connecting line for a gas bag-type occupant protection system. 
     BRIEF DESCRIPTION OF THE INVENTION 
     To this end, the invention provides a connecting line intended to connect a gas bag for a gas bag-type occupant protection system with a gas generator. The connecting line comprises a gas exit section intended to be arranged within a gas bag and having outer surface area. The gas exit section is provided with at least one gas exit port. The gas exit port has at least one gas guidance surface area which extends from the outer surface area of the gas exit section into the interior of the gas exit section of the said connecting line with a predetermined depth. Due to such a geometry each gas exit port features a gas guidance surface area by which the gas flowing in the gas exit section of the connecting line is forced to exit laterally. In this arrangement, the branching gas flow can be influenced in regard to its direction and extent by changing the geometry of the gas exit port. The gas exit port may be fabricated by indentation or embossing. The gas exit port may be fabricated in a single operation for example by means of a combined embossing/cutting punch. Small tolerances are achieved in production when a cutting die is drawn along in the interior of the connecting line in the manufacturing process. 
     In one aspect of the invention the gas guidance surface area comprises in the predetermined depth at least one end face oriented towards a main flow direction of the gases in the connecting line. Configuring the gas guidance surface area in this way causes an outflow of the gases substantially in a plane parallel to the cross-section of the connecting line. 
     In another aspect it is proposed that the gas exit port comprises at least one boundary located in the outer surface area of the gas exit section and oriented parallel to the main flow direction and that the gas guidance surface area is formed by an indented portion of the wall of the gas exit section of the connecting line, this indention being located on the side of the boundary relative to the main flow direction. In this way a flow-favoring geometry can be created by simple means of fabrication without the need of fitting additional parts to the connecting line. The dimensions of the indented portion influence the direction and quantity of the outflowing gas. 
     In yet a further aspect of the invention it is also proposed that the gas guidance surface area is formed by a portion of the wall of the gas exit section of the connecting line, that is indented between two boundaries located parallel to the main flow direction. As a result of this, the open cross-section of the gas exit port available for outflow of the gas can be enlarged without changing the depth of the gas exit port. 
     It is likewise of advantage that the gas guidance surface area extends opposite a main direction of gas flow in the connecting line toward the gas bag obliquely down from the outer surface area of the gas exit section of the connecting line to a predetermined depth into the interior of the connecting line. Due to such a gilled geometry the gas flowing in the connecting line is deflected directly from its main flow direction, and the gas flowing in the gas exit section of the connecting line is forced to exit laterally. In this arrangement, the branching gas flow can be influenced as regards its direction and extent by changing the geometry of the gas exit port. 
     The gas guidance surface area may be configured so that it comprises in the predetermined depth an end face facing the main flow direction and that the width of the gas guidance surface area reduces from the end face toward the outer surface area of the gas exit section of the connecting line. The gas guidance surface area is preferably curved convex. For example, flow-favoring geometries of the gas exit port may be produced by varying the penetration depth of a circular cone-shaped punch, the gas guidance surface area as viewed from above then having essentially a triangular or hyperbola-like curved rim. 
     In still another aspect of the invention the gas exit section of the connecting line extending into the gas bag comprises a plurality of gas exit ports arranged in series in the main flow direction, the cross-section of the gas exit ports perpendicular to the main flow direction for the gas exit ports located further downstream in the main flow direction being larger than that of the gas exit ports located further upstream. In this way the drop in pressure of the gas along the connecting line can be compensated so that the outflow of gas at all gas exit ports is the same in quantity. 
     It is also proposed that the predetermined depth of the gas exit ports located further downstream in the main flow direction is larger than that of the gas exit ports located further upstream, this enabling the cross-section available for the gas passage to be increased by simple means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features and advantages of the invention read from the following description and are evident from the drawing to which reference is made and in which: 
     FIG. 1 is a schematic side view of a first embodiment of a gas bag-type occupant protection system in accordance with the invention, 
     FIG. 2 shows a portion of the connecting line as shown in FIG. 1 in the region of a gas exit port as seen from above, 
     FIG. 3 is a section view of the gas exit section of the connecting line as shown in FIG. 2 taken along the line III—III, 
     FIG. 4 is a section view of the gas exit section of the connecting line as shown in FIG. 3 taken along the line IV—IV, 
     FIG. 5 shows a portion of a second embodiment of a connecting line in accordance with the invention in the region of a gas exit port as seen from above, 
     FIG. 6 is a section view of the gas exit section as shown in FIG. 5 taken along the line VI—VI, 
     FIG. 7 is a section view of the gas exit section as shown in FIG. 5 taken along the line VII—VII, 
     FIG. 8 shows a portion of a third embodiment of the connecting line in accordance with the invention in the region of a gas exit port as seen from above, 
     FIG. 9 is a section view of the gas exit section as shown in FIG. 8 taken along the line IX—IX and 
     FIG. 10 is a section view of the gas exit section as shown in FIG. 8 taken along the line X—X, 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1 there is illustrated a gas bag-type occupant protection system in accordance with the invention arranged on a vehicle structure  10  indicated dot-dashed. Indicated in this vehicle structure  10  are side windows  12 . A gas bag  14  covers the side windows at least in part when deployed and is connected to the vehicle structure  10  via fastening points  16  and tensioning straps  18 . Inflating the gas bag  14  is done by an inflator  20  which is connected to the gas bag  14  via connecting line  22 . The main direction of flow of the gases in the connecting line  22  to the gas bag  14  is indicated by the arrow. Extending within the gas bag  14  is a gas exit section  24  of the connecting line  22  which is provided with a plurality of gas exit ports  26 ,  28 ,  30  and  32 . The spacing of the gas exit ports  26 ,  28 ,  30  and  32  is greater between the gas exit ports  30  and  32  located further downstream in the main flow direction than between the gas exit ports  26  and  28  located further upstream. The gas exit ports  26  to  32  serve to ensure uniform inflation of the gas bag  14  during its deployment. 
     Referring now to FIG. 2 there is illustrated the gas exit section  24  with the gas exit port  26  as seen from above. Here too, the main direction of flow of the gases is indicated by an arrow. As viewed from above the gas exit port  26  is triangular in shape, the width of which diminishes in the main flow direction. 
     Referring now to FIG. 3 there is illustrated a section view of the gas exit section  24  of the connecting line  22  in the region of the gas exit port  26 . The gas exit port  26  comprises a gas guidance surface area  34  oriented opposite the main flow direction as indicated by the arrow, and extending from the outer surface area  36  of the gas exit section  24  down to a predetermined depth t into the interior of the gas exit section  24  of the connecting line  22 . The gas guidance surface area is formed by an indented part of the wall of the gas exit section acting as a guide plate. Gas flowing along gas exit section  24  of the connecting line  22  is diverted by the gas guidance surface area  34  from the main flow direction and guided into the interior of the gas bag. Direction and quantity of the diverted gas flow depend on the depth t and other dimensions of the cross-section of the gas exit port  26  available for gas passage as well as on the angle of inclination of the gas guidance surface area  34  relative to the main flow direction. 
     Referring now to FIG. 4 there is illustrated a section view of the gas exit section  24  as taken along the line IV—IV in FIG.  3 . In the view as evident from FIG. 4 the gas guidance surface area  34  is curved in the shape of a circular segment in a plane perpendicular to the main flow direction. It is thus evident from FIGS. 2,  3  and  4  that the gas guidance surface area  34  is formed by indenting the wall of the gas exit section  24  of the connecting line, this gas guidance surface area being convex and the indentation being achieved by a punch in the shape of a circular cone tapered in the main flow direction. This punch is a combined embossing/cutting punch which incises the gas exit section  24  transversely to the main flow direction and forms the gas exit port  26  down to the depth t, i.e. the gas exit port  26  being formed in a single operation. When employing a plurality of such embossing/cutting punches a plurality of gas exit ports  26 ,  28 ,  30  and  32  can be produced at the same time in the gas exit section  24  of the connecting line  22 . The gas exit ports  26 ,  28 ,  30  and  32  may be produced without machining, any burrs resulting from cutting thus being located in the interior of the connecting line  22  so that the gas bag can not be damaged. 
     Referring now to FIG. 5 there is illustrated a view as seen from above of a gas exit section  40  of a connecting line having a gas exit port  42 . The gas exit port  42  comprises a boundary  44  located in the outer surface area of the gas exit section  40 , this boundary being oriented parallel to the main flow direction as indicated by the arrow. A gas guidance surface area  46  is formed by indenting a portion of the wall of the gas exit section  40 , this portion being located to the side of the boundary  44 . As viewed from above the gas guidance surface area  46  has substantially the shape of a circular segment. 
     Referring now to FIGS. 6 and 7 there is illustrated the gas guidance surface area  46  extending obliquely into the interior of the gas exit section  40  and comprising in the depth t a end face  48  oriented parallel to the main flow direction of the gases in the connecting line. For producing the gas exit port  42  as shown in FIG. 6 the gas exit section  40  is cut open along the boundary  44  and subsequently the gas guidance surface area  46  is configured by indenting a portion of the outer surface area located laterally of the boundary  44 . The arrow as evident from FIG. 6 illustrates the main outflow direction of the gases from the gas exit port  42 . 
     Referring now to FIG. 8 there is illustrated an embodiment of the invention in which in a gas exit section  50  of a connecting line a gas exit port  52  is configured. The gas exit port  52  comprises two boundaries  54  and  56  located parallel to the main flow direction as indicated by an arrow, it being between these boundaries that a portion of the wall of the gas exit section  50  is indented. This indented portion forms the gas guidance surface area  58  consisting of three sections. 
     Referring now to FIG. 9 the main outflow direction of the gases from the gas exit port  52  is indicated by two arrows: on both sides of the gas guidance surface area  58  gas escapes from the gas exit section  50  through the open cross-section formed between the boundaries  54  and  56  and the end faces  60  and  62  of the gas guidance surface area  58 . 
     Referring now to FIG. 10 there is illustrated a section view indicating that the gas guidance surface area  58  comprises a first section extending from the outer surface area of the gas exit section  50  obliquely down to the depth t into the interior of the gas exit section  50 , a second section running parallel to the main flow direction as indicated by the arrow, in the depth t, and a third section running from the depth t obliquely to the outer surface area.