Air bag apparatus for a vehicle

Abstract: A longitudinal pad (10) is fixed within a roof rail (4) and has a hat-shaped cross-section that protrudes into the passenger compartment of the vehicle. A deformable longitudinal cover (14) disposed beneath the pad (10), on the inner surface of the roof rail (4), has an upper end fixed to the top of the pad (10), a lower end in proximity to the roof rail (4), and a substantially L-shaped cross-section. The folded air bag (18) is housed between the roof rail (4) and the cover (14) and, when the vehicle experiences a collision, pushes outward between the lower end of the cover and the roof rail, so as to form an aperture (39) therebetween, from which the air bag deploys downward. In other embodiments, the pad is omitted and the upper end of the cover is fixed to the roof rail.

Description: The present invention relates to air bag apparatus for a vehicle. The body of an automobile has a roof rail in proximity to the head of a passenger, and a pad with a cross-sectional shape of a hat, i.e. a channel section, provided on the roof rail. When a side collision or the like occurs, if a passenger's head comes into contact with this pad, deformation of the pad absorbs the energy of the collision with the head, thereby protecting the head of the passenger. Recently, there have been cases in which an air bag is disposed on the roof rail as protection in the case of a side collision, and technology related to this is disclosed in Japanese laid-open patent application publication H9-156450. In an air bag apparatus of this type, a folded-up air bag is disposed in proximity to the roof rail, this air bag expanding downward so as to protect the head of a passenger in the case of a side collision. With the above-noted structure, because it is necessary to position both the air bag apparatus and the pad above at a position on the roof rail that is near the passenger's head, it is difficult to locate both of these elements, because of space restrictions, in a manner that prevents loss of the functionality thereof. Accordingly, it would be desirable to be able to provide air bag apparatus that, in addition to the function of the air bag, also enables the pad to serve in a protective role. EP-A-841 221 discloses an air bag apparatus in accordance with the preamble of claim 1. DE-A-19752989 discloses an air bag apparatus in which a longitudinal cover for an air bag has mounting tabs fixed to a roof rail. The present invention provides air bag apparatus as set forth in claim 1. Preferred and optional features are set forth in the dependent claims. Because the upper end of the cover is fixed to the top surface of the energy-absorbing member, when the air bag expands within the cover due to a side collision of the vehicle, the air bag applies pressure so as to open up an aperture between the lower end of the cover and the roof rail, and expands downward through the aperture so as to protect the head of a passenger. In the case in which the side collision is not of a degree that would cause the air bag to expand, the energy-absorbing member and the metal cover deform, thereby serving to absorb the collision energy to which the passenger's head is subjected. For this reason, it is possible to sufficiently absorb the energy of collision. Thus, even using a small energy-absorbing member, it is possible to achieve both the energy-absorbing function of the air bag and the energy-absorbing function of the energy-absorbing member, thereby providing energy absorption that is appropriate to the strength of the side collision. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exploded perspective view of one embodiment of an air bag apparatus in accordance with the present invention. Fig. 2A is a cross-section view in the direction of the arrows IIa-IIa shown in Fig. 1. Fig. 2B is an enlarged plan view in the direction of the arrow IIb in Fig. 2A. Fig. 3 is a cross-section view of an embodiment of an air bag apparatus not in accordance with the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention is described below in detail, with reference being made to relevant accompanying drawings. Fig. 1, Fig. 2A, and Fig. 2B show the preferred embodiment of the present invention. Fig. 1 is a perspective view of the upper part of a vehicle as seen from the passenger compartment 40 thereof, and Fig. 2A is a cross-section view in the direction of the arrows IIa-IIa shown in Fig. 1. As shown in Fig. 1 and Fig. 2A, the upper ends of a front pillar 1, a center pillar 2, and a rear pillar 3 are joined by a roof rail 4 extending in the front-to-back direction of the vehicle. The roof rail 4 has a closed cross-section and is formed by a roof rail outer part 5 and a roof rail inner part 6. The upper end of the roof rail 4 is joined to the end of the roof panel 7, the joint between these two elements forming a roof drip 8 for the purpose of water runoff. A weather strip 9 for the purpose of ensuring watertightness with a door (not shown in the drawing) is mounted to the lower end of the roof rail 4. The surface 6a of the roof rail inner part 6 (inner surface of the roof rail 4) has welded to it a double flange part 41 on the open side of a channel-shaped metal pad 10 (energy-absorbing member). The width 32 of the pad 10 is established so as to be small, so as to establish an inner space 70 for housing the air bag 18 to be described below. Mounting holes 10a, at spacings of 34a, 34b, 34c, and 34d, are formed in the uppermost surface 33 of the pad 10. A nut 24 into which a bolt 23 for mounting the cover 14, to be described below, is welded to the rear surface of the mounting hole 10a, the bolt 23 and nut 24 constituting fastening members. A deformable region 12 is formed by an arc-shaped slit 11 formed in the roof rail inner part 6 so as to be an incomplete circuit with a part remaining at the bottom, the position of which corresponds to the position of the nuts 23 (refer to Fig. 2B). When pressed by the nut 24, this deformable region 12 is pressed into the inside of the roof rail 4, thereby allowing the bolt 23 or the nut 24 to be moved to inside the roof rail 4. A cover 14 having a substantially L-shaped cross-section is disposed below the pad 10. The cover 14 is formed by a front cover 15 and a rear cover 16, the rear end of the front cover 15 and the front end of the rear cover 16 being linked in a position in proximity to the upper part of the center pillar 2. Mounting tabs 17 extend from the front and rear end of the covers 15 and 16 and from the upper center thereof. Mounting holes 17a corresponding to the positions of the mounting holes 10a are formed in these mounting tabs 17. That is, the spacings 35a, 35b, 35c, and 35d of the mounting holes 17a in the mounting tabs 17 are established so as to be the same as the spacings 34a, 34b, 34c, and 34d of the mounting holes 10a of the pad 10. Additionally, the spacings 34a, 34b, 34c, and 34d are established so that the flexure of the cover 14 when the air bag 18 expands is within a prescribed limit. Mounting holes 17a and 38 are formed in a part in which the mounting tab 36 at the front edge of the rear cover 16 bent forward so as to overlap with the mounting tab 37 at the rear edge of the front cover 15. The cover 14 and the pad 10 have the same deformed shape, and have substantially the shock shock-energy absorbing characteristics. By making the sheet thickness, the material, and the cross-section shape of the cover 14 and the pad 10 substantially the same, the shock energy absorption characteristics are established as being substantially the same. A folded-up air bag 18 is housed in the space 70 defined between the roof rail inner part 6 and the cover 14. The upper end of the air bag 18 is engaged with the upper end part of the cover 14, with the exception of the mounting tabs 17, and the lower end of the air bag 18 is supported by tiebacks 19. The upper edge 19a of each tieback 19 is engaged with the upper edge 14a of the cover 14, and the lower edges 19b of the tiebacks 19 are engaged with the lower wall 13 of the cover 14. For this reason, the tiebacks 19 can be easily removed from the cover 14. A supporting piece 20, which extends downward at an inclination along the front pillar 1 is formed at the front end of the tiebacks 19, the end of the supporting piece 20 and the front pillar 1 opposite this front end having formed in them mounting holes 1a and 20a, respectively. The rear end of the air bag 18 is exposed to the rear from the cover 14, and is connected to an inflator 21 which generates a gas for the purpose of inflating the air bag 18. A front and rear pair of brackets 21 is mounted to the inflator 21. Mounting holes 22a are formed at the upper and lower ends of the brackets 22, and mounting holes 3a are formed in the rear pillar 3 at positions corresponding to these mounting holes 3a. The process of mounting the cover 14, the air bag 18 and other elements to the roof rail inner part 6 is performed as follows. A pad 10 is pre-welded to the roof rail 6, the air bag 18 that is folded up inside the cover 14 is supported by the tiebacks 19. The rear end of the air bag 18 is connected to the inflator 21. First, the cover 14 and the air bag 18 are placed within the passenger compartment 40. When this is done, because the cover 14 is divided between the front and rear covers 15 and 16, it is easy to place them within the passenger compartment 40. After placing the cover 14 and the air bag 18 within the passenger compartment 40, the mounting holes 17a of the mounting tabs 17 are positioned so as to be opposite the mounting holes 10a of the pad 10, and the bolts 23 are inserted into the mounting holes 17a and 10a and tightened into the nuts 24 that are welded to the pad 10, thereby fixing the mounting tabs 17 to the uppermost surface 33 within the pad 10. The overlapped mounting tabs 36 and 37 are fixed in the same manner as the mounting tabs 17a, so that the front and rear covers 15 and 16 are linked via the mounting tabs 36 and 37. Because the mounting tabs 36 and 37 are tightened in place by a single bolt, there is only one bolt required, thereby improving work efficiency. The supporting piece 20 of the tieback 19 is tightened in place to the center pillar 1 by means of a bolt (not shown in the drawing), which passes through a nut (not shown in the drawing) and the mounting holes 1a and 20a. By mounting the cover 14 in the above-noted manner, the air bag 18 is substantially housed in the space 70 between the roof rail inner part 6 and the cover 14. Although the lower wall 13 of the cover 14 is not fixed to the roof rail inner part 6, the rigidity of the cover 14 itself maintains its proximity to the roof rail inner part 6. Next, the inflator 20 is connected to the rear end of the air bag 18, and bolts and nuts (not shown in the drawing) are used to tighten the mounting holes 22a of the brackets 22 and the mounting holes 3a of the center pillar 3. After mounting the cover 14 and the air bag 18 and other elements to the roof rail inner part 6 in this manner, the inner-facing side of the cover 14 is covered by the garnishing 25 and the roof trim 26. The action of the first embodiment of the present invention is as follows. First, when a side collision of the vehicle is sensed by a sensor (not shown in the drawing), gas is injected into the air bag 18 from the inflator 20, causing the start of bag inflation. The cover 14 is fixed only at its upper end to the mounting tabs 17, and is not fixed to the lower wall 13. For this reason, when the air bag 18 expands, the cover 14 is pushed upward, so that it opens about the mounting tabs 17 which serve as hinges, the result being that that the end 13a of the lower wall 13 is released from the lower ends 19b of the tiebacks 19 and away from the roof rail inner part 6, so that an aperture 39 is formed between the lower wall 13 and the roof rail inner part 6. The air bag 18 then extends downward through the aperture 39 in a curtain-like manner, so as to protect the head of the passenger. Because the spacings 34a, 34b, 34c, and 34d of the mounting holes 10a of the pad 10 are established so that the flexure of the cover 14 when the air bag 18 expands is within a prescribed limit, the cover 14 is not excessive in the longitudinal direction thereof, the cover 14 being pushed upward by the air bag 18, so as to form an aperture 39 of sufficient size, the result being good deployment of air bag 18 downward. Because the shock energy absorption characteristics of the pad 10 and the cover 14 are substantially the same, in the case in which a side collision is not of a degree that would cause the air bag 18 to deploy, the head of the passenger comes into contact with the pad 10 and the cover 14, so that the shock energy to which the head is subjected is absorbed by the pad 10 and the cover 14. Thus, the cover 14 and the pad 10 have equivalent functions, and act in concert to absorb the shock energy. Because the cover 14 has a function that is equivalent to that of the pad 10, the reduction in energy absorption amount by the pad 10 caused by making the width 32 thereof small is compensated for by the energy absorption by the cover 14, so that there is sufficient overall energy absorption. Therefore, it is possible even using a small pad 10 to achieve both energy absorption by the air bag 18 and energy absorption by the deformation of the material of the pad 10 and the cover 14, making it possible to provide energy absorption that is appropriate to the strength of the side collision. The shock energy absorption characteristics of the combination of the pad 10 and the cover 14 can be easily adjusted, by selecting the material thickness, material, and cross-sectional shape of the cover 14 and the pad 10. Additionally, the roof rail inner part 6 has formed in it deformable regions 12 at positions corresponding to the positions of the nuts 24 of the pad 10. For this reason, when the pad 10 is deformed, the ends of the bolts 23 which protrude toward the roof rail inner part 6 from the uppermost surface 33 of the pad 10 interfere with these deformable regions 12. When the bolts 23 interfere with and push against the deformable regions 12, the deformable regions 12 are pushed outward toward in the lateral (vehicle width) direction (to the inside of the roof rail 4), holes defined by the slit 11 being formed, and the ends of the bolts 23 entering the roof rail 4 from these holes. For this reason, the amount of deformation of the pad 10 increases, this representing an improvement in the absorption of the shock energy to which the head is subjected. In addition, because the cover 14 is divided front-to-back, the shock energy absorption characteristics at the division point thereof (the part at which the front and rear covers 15 and 16 are linked) is not as good as at other parts. However, because the division point is in the region of the center pillar 2, at which there is the smallest chance of being contacted by the head of a passenger, it is possible to minimize the problem of having the cover 14 divided in this manner. Instead of using bolts 23 and nuts 10 to fix the cover 14, it is possible to use rivets or the like, and instead of using a deformable region 12, it is possible to form holes in the roof rail inner part 6 through which the ends of the bolts 23 can be inserted. Fig. 3 is a cross-section view showing an embodiment of an air bag apparatus which is not in accordance with the present invention, since the pad 10 is not provided, padding being provided by a cover 27 only (by deformation of the material thereof). In this embodiment, a metal cover 27 having a substantially U-shaped cross-section that is opposite to and matches the U-shaped inner surface 6a of the roof rail inner part 6 is formed over the surface 6a. Mounting tabs 28 are formed at a prescribed interval on the cover 27, these mounting tabs 28 being tightened to the roof rail inner part 6 by bolts 23 and nuts 24. Because there is only a cover 27 and no pad over the surface 6a, compared to the case of the embodiment 1, in which there is a pad 10 and a cover 14, there is a larger deformation of the width 43 of the cover 27, the capacity thereof being large. For this reason, the air bag 31 in the space 70 between the roof rail inner part 6 and the cover 27 is folded up so as to overlap in the width 43 direction of the cover 27. The lower end 29a of the lower wall 29 of the cover 27 is in proximity to the roof rail inner part 6. A protrusion 30 protruding toward the inside of the passenger compartment 40 is formed in the lower end of the roof rail inner part 6, the lower end 29a of the lower wall 29 engaging with this protrusion 30. When the air bag 31 expands because of a side collision, the cover 27 is pushed upward, so that end 29a of the lower wall 29 moves away from the protrusion 30, the cover 27 opening up about the mounting tabs 28 as a hinge, the result being that the end 29a moves away from the roof rail inner part 6, thereby forming an aperture (not shown in the drawing) between the lower wall 29 and the roof rail inner part 6, through which the air bag 31 deploys downward. Because the cover 27 being pushed upward causes the end 29a of the lower wall 29 to move upward and away from the protrusion 30, the protrusion 30 does not interfere with the opening of the cover 27. In the case in which a side collision is not strong enough to cause the deployment of the air bag 31, the head of the passenger comes into contact with the cover 27, which deforms, thereby absorbing the shock energy of the head. When this occurs, the downward opening movement of the lower wall 29 of the cover 27 is prevented by the protrusion 30. For this reason, the cover 27 tends not to deform, so that there is an increase in the amount of absorbed shock energy, this representing an improvement in the protection afforded the head of the passenger. Other elements of this embodiment are the same as described with reference to Figure 1.

Claims: An air bag apparatus for a vehicle, comprising: an energy-absorbing member (10) extending longitudinally and being fixed onto the inner surface of a roof rail (4) so that the top (33) of the energy-absorbing member (10) protrudes into a passenger compartment of the vehicle, the roof rail (4) preferably comprising a roof rail inner part (6) and a roof rail outer part (5); a longitudinal cover (14) disposed below the energy-absorbing member (10) on the inner surface of the roof rail (4), the cover(14) having an upper end fixed to the top (33) of the energy-absorbing member (10) and a lower end disposed in proximity to the roof rail (4), an inner space (70) being defined by the cover (14); and a folded air bag (18) housed in the inner space (70); the energy-absorbing member (10), preferably made of metal, is substantially channel-shaped; and wherein, when the air bag (18) is inflated, it presses against the cover (14), the lower end of the cover (14) moves away from the roof rail (4), an aperture (39) is formed between the roof rail (4) and the lower end of the cover (14), and the air bag (18) expands downward through the aperture (39); characterised in that the energy-absorbing member (10) has its open side fixed onto the inner surface of the roof rail; the said inner space (70)is defined between the roof rail (4) and the cover (14), which is preferably made of metal; and a fixing member (23,24) fixes the cover (14) to the top (33) of the energy-absorbing member (10) and the roof rail (4) includes a part (12) disposed in opposition to the fixing member (23,24) for allowing intrusion of the fixing member into the roof rail. Air bag apparatus according to claim 1, wherein the energy-absorbing member (10) and the cover (14) have substantially the same shock energy absorption characteristics. Air bag apparatus according to claim 1, wherein the intrusion-allowing part is a deformable part (12) allowing the fixing member (23,24) to intrude into the roof rail when the energy-absorbing member (10) is deformed so as to apply pressure to the roof rail (4), the deformable part (12) preferably being defined by a slit (11) formed in the roof rail (4). Air bag apparatus according to any of claims 1 to 3, wherein the lower end of the cover(14) is engageable with an engaging part on an inner surface of the roof rail, the inflated air bag (18) removing the lower end from the engaging part and causing the cover (14) to rotate about its upper end. Air bag apparatus according to any of claims 1 to 4, wherein the cover (14) comprises a front cover (15) and a rear cover (16), the rear end of the front cover and the front end of the rear cover being linked together, preferably near a center pillar (2). Air bag apparatus according to claim 5, wherein the rear end of the front cover (15) has a mounting tab (37) extending from its upper end, the front end of the rear cover (16) has a mounting tab (36) extending from its upper end, and the mounting tabs (36,37) mutually overlap and are fixed to the roof rail (4). Air bag apparatus according to any of claims 1 to 5, wherein the cover (14) has mounting tabs (17) disposed so as to be longitudinally separated from one another, extending from the upper end thereof, the mounting tabs (17) being fixed to the roof rail (4) and disposed at a prescribed interval that limits flexure of the cover (14) to within a prescribed limit when the air bag (18) deploys.

Inventors: ISHIGOUOKA KIYOHARU, KOGA YOSHIHIRO, MIYAHARA TAKEHIKO, NARITA MASANORI, ISHIGOUOKA, KIYOHARU, KOGA, YOSHIHIRO, MIYAHARA, TAKEHIKO, NARITA, MASANORI
Applicants: NISSAN MOTOR, NISSAN MOTOR CO., LTD.
Application year: 1999
Main classification: B60R21
IPC codes: B60R21