Occupant protection system

An occupant protection system in which an airbag module can easily be mounted to a seat is provided. A retainer is placed on the inner surface of the lower part of an airbag. Stud bolts projecting downward from the lower surface of the retainer are passed through bolt insertion holes of the airbag, to which first nuts are tightened from the exterior of the airbag through a patch; thus, the airbag is joined to the retainer. A gas generator is joined to the retainer with a bracket. A seat pan has a recess for accommodating the patches and the first nuts when the retainer to which the airbag and the gas generator have been joined in advance is mounted thereto.

FIELD OF THE INVENTION

The present invention relates to an occupant protection system for protecting an occupant of a vehicle such as a car in the event of a crash and, more specifically, it relates to an occupant protection system for preventing the body of the occupant from moving forward and downward by restraining the waist of the occupant during a front crash.

BACKGROUND OF THE INVENTION

As a system for protecting an occupant in the event of a car crash, Japanese Unexamined Patent Application Publication No. 10-217818 describes an occupant protection system in which the front of a seat cushion is increased in height or hardened during the car crash to prevent a so-called submarine phenomenon such that the occupant passes under a lap belt during a front crash even with a seat belt.

The occupant protection system disclosed in the patent has a recess in the front of a seat pan, in which an airbag is arranged.

A cylindrical inflator is disposed in the airbag, from which a stud bolt projects downward. The bolt passes through the airbag and a seat pan and projects downward therefrom. A nut is tightened to the bolt, so that the inflator is drawn to the seat pan and fixed thereto and the bottom of the airbag is clamped between the inflator and the seat pan; the airbag is thus joined to the seat pan.

With the occupant protection system described in the Japanese Unexamined Patent Application Publication No. 10-217818, the stud bolt of the inflator is passed through the hole of the airbag and further passed through the hole of the seat pan. The bolt, however, comes off easily from the hole of the airbag before the bolt is passed through the hole of the seat pan, having the problem of burdensome assembly work.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an occupant protection system in which an airbag module can easily be joined to a seat.

An occupant protection system according to the present invention includes: an airbag disposed between a seat pan and a seat cushion and inflatable to push the seat cushion from below; and a gas generator disposed in the airbag, the airbag and the gas generator being joined to the seat pan. The airbag and the gas generator are joined to the seat pan after the airbag and the gas generator have been joined together.

In the occupant protection system of the invention, the airbag and the gas generator are joined together before the airbag and the gas generator are joined to the seat pan, which are then joined integrally to the seat pan. Accordingly, the bolt does not come off from the hole of the airbag when the airbag and the gas generator are mounted to the seat pan, proving efficient work.

According to an aspect of the invention, a bolt projects from the gas generator or the gas-generator retainer, the bolt passing through the airbag and the seat pan; the airbag and the gas generator are joined together by a first nut being tightened to the bolt; and the airbag and the gas generator are joined to the seat pan by a second bolt being tightened to the bolt. Since the first nut is tightened to the bolt in advance, in this way, the airbag and the gas generator are easily integrated. Moreover, the coming-off of the bolt from the hole of the airbag can reliably be prevented.

In the invention, preferably, the seat pan has a recess for accommodating the first nut.

With such a structure, the height of the installation of the airbag and the gas generator can be decreased. In other words, the airbag and the gas generator are not arranged in a higher position corresponding to the thickness of the first nut, even with the first nut provided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described with reference to the drawings.FIG. 1is a perspective view of the frame of a seat including an occupant protection system according to the embodiment of the present invention;FIG. 2is a sectional view taken along line II-II ofFIG. 1;FIG. 3is a perspective sectional view of a seat pan;FIG. 4is a perspective view of an airbag module of the occupant protection system, viewed from below;FIG. 5is an exploded view of the airbag module; andFIG. 6is an exploded view of the airbag module and the seat pan.

The frame of the car seat includes a base frame1and a back frame4rotatably joined to the base frame1through a support shaft2and a reclining device (not shown). The back frame4has a headrest6thereon.

The base frame1has left and right side frames1aand1b. A seat pan8is placed between the front of the side frames1aand1b. The seat pan8has side walls8aand8brising from the left and right opposite ends thereof, which overlap with the inner sides of the side frames1aand1b(opposing sides of the side frames1aand1b). The side frames1aand1band the side walls8aand8beach have bolt insertion holes (not shown) so as to pass through the overlapping frames and side walls, into which bolts1care each inserted and nuts8care tightened to the bolts1c, so that the seat pan8is fixed between the side frames1aand1b.

The base frame1and the back frame4include a seat cushion and a seatback (not shown), made of urethane or the like, respectively. The seat pan8is arranged under the front of the seat cushion.

The seat pan8has an airbag module10of the occupant protection system mounted thereto.

The airbag module10is arranged between the seat pan8and the seat cushion, in a folded condition. The airbag module10includes an airbag12which is inflated to push the seat cushion from below by the introduction of gas, a gas generator14for inflating the airbag12, a retainer16to which the airbag12and the gas generator14are joined and which is fixed to the seat pan8with later-described stud bolts20, and an enclosure18that encloses the folded airbag12so as to restrain the airbag12in the folded condition. The airbag12is arranged so as to extend along the lateral width of the seat pan8(along the vehicle width).

In this embodiment, the seat pan8has, on the top, an airbag module housing8d(refer toFIG. 3) formed of a recessed step that is reduced in height by the length corresponding to the height (vertical size) of the airbag module10. The airbag module10is disposed in the airbag module housing8d.

The retainer16in this embodiment is shaped like a plate extending along the bottom of the airbag module housing8d. The retainer16is disposed in the airbag12, in contact with the inner surface of the lower part of the airbag12so as to push the lower part of the airbag12against the bottom of the airbag module housing8dfrom the interior of the airbag12. From the lower surface of the retainer16, the stud bolts20project downward. The stud bolts20each project to the exterior of the airbag12through a bolt insertion hole12a(refer toFIG. 5) formed in the lower part of the airbag12. The airbag12is joined to the retainer16such that first nuts24are tightened to the stud bolts20from the exterior of the airbag12through patches22. Numeral22aofFIG. 5denotes a bolt insertion hole of each patch22through which the stud bolt20is passed.

The enclosure18is routed under the airbag12so as to cover the first nuts24. The stud bolts20extend further downward through the enclosure18.

The stud bolt20is further passed through a bolt insertion hole8e(refer toFIG. 6) formed in the bottom of the airbag module housing8d. A second nut26is tightened to the stud bolt20from below the seat pan8; thus, the retainer16is fixed to the bottom of the airbag module housing8d.

Referring toFIG. 6, the airbag module housing8dhas a recess28in the bottom, which has a depth that can accommodate the patches22placed on the outer surface of the lower part of the airbag12, the first nuts24, and so on entirely when the retainer16is arranged along the bottom. The width of the recess28is smaller than that of the retainer16. The bolt insertion holes8eare arranged in the recess28.

Accordingly, as shown inFIG. 2, when the stud bolts20are passed through the bolt insertion holes8e, on which the nuts26are tightened from below the seat pan8, the patches22and the first nuts24are accommodated in the recess28, and so the retainer16is brought into close contact with the bottom of the airbag module housing8dthrough the ground fabric of the airbag12.

The gas generator14is mounted to the upper surface of the retainer16with a bracket30. The gas generator14is substantially cylindrical in this embodiment, which is arranged in the airbag12such that the axis is directed along the lateral width of the seat pan8. The bracket30projects from the front rim of the retainer16(the rim on the front of the vehicle) and includes a C-shaped band30acurved in substantially C-shape on the upper surface of the retainer16and a flange30bextending from the end of the C-shaped band30aso as to cover the upper surface of the retainer16. The stud bolts20project downward from the lower surface of the flange30band pass through the retainer16to extend downward therefrom.

The gas generator14is inserted into the C-shaped band30aand then the first nuts24are tightened to the stud bolt20to clamp the flange30band the retainer16by pressure, so that the gas generator14is fixed to the retainer16.

The enclosure18of this embodiment is shaped like a bag that encloses the entire folded airbag12, as shown inFIG. 4. The perimeter of the enclosure18is set shorter than that of the inflated airbag12and so the maximum perimeter of the inflated airbag12is limited to the perimeter of the enclosure18to increase the inner pressure of the airbag12.

In the occupant protection system with such a structure, the airbag module10is assembled to the state ofFIG. 4in which the airbag12and the gas generator14are each joined to the retainer16before it is mounted to the seat pan8, the airbag12is folded, and the enclosure18is mounted to the folded airbag12.

More specifically, the gas generator14is inserted into the C-shaped band30aof the bracket30in advance and the retainer16is disposed inside the airbag12. Referring toFIG. 5, the stud bolts20are inserted into the bolt insertion holes12aat the lower part of the airbag12. Subsequently, the first nuts24are tightened to the stud bolts20from the exterior of the airbag12through the patch22to join the airbag12and the retainer16together. At that time, the flange30bof the bracket30and the retainer16are clamped by the tightening of the first nuts24; thus, the gas generator14is fixed to the retainer16. Thereafter the airbag12is folded and then the enclosure18is covered over the folded airbag12.

The airbag module10assembled in that way is then disposed in the airbag module housing8dof the seat pan8. At that time, the stud bolts20are inserted into the bolt insertion holes8e, to which the second nuts26are tightened to the stud bolts20from the lower surface of the seat pan8. Accordingly, the airbag module10is fixed to the seat pan8.

In this occupant protection system, before the airbag module10is mounted to the seat pan8, the airbag12and the gas generator14have been joined to the retainer16and also the airbag12has already been folded, which facilitates the assembly work of the airbag module10to the seat pan8.

According to this embodiment, although the patches22and the first nuts24which join the airbag12to the retainer16project downward from the lower surface of the retainer16, the airbag module housing8dhas the recess28in the bottom for accommodating them. Accordingly, when the retainer16is disposed in the airbag module housing8d, the patches22and the first nuts24are accommodated in the recess28, so that the retainer16is brought into close contact with the bottom of the airbag module housing8dthrough the airbag12. Thus, the lower part of the airbag12is firmly clamped between the retainer16and the bottom of the airbag module housing8dto stable the position of the inflated airbag12.

Referring now toFIGS. 10 to 12, the structure in which the gas generator14and the retainer16are arranged in the airbag12, which has not been shown inFIGS. 1 to 6, will be described hereinafter.

FIG. 10is an exploded perspective view of the structure in which the gas generator14and the retainer16are arranged in the airbag12;FIG. 11is a perspective view of the gas generator14and the retainer16being inserted into the airbag12; andFIG. 12is a perspective view of the airbag12in which the gas generator14and the retainer16have been arranged.

Referring toFIG. 10, the airbag12has a slit (cut)50in the lower surface, for the gas generator14and the retainer16to insert. As illustrated, the airbag12has two bolt insertion holes12ain the lower surface, for the two stud bolts20projecting from the lower surface of the retainer16to pass through. While opposite ends of the slit50connect to the bolt insertion holes12a, the arrangement of the slit50is not limited to that. For example, the slit50may be arranged in a position remote from the bolt insertion holes12a. The width and the length of the slit50are set as appropriate depending on the size of the gas generator14and the retainer16.

The airbag12also has a cover cloth52on the lower surface, for covering the slit50and the bolt insertion holes12a. One half of the cover cloth52is a base piece54attached to the periphery of the slit50and the bolt insertion holes12awith mounting means such as stitching, while the other half is a cover56folded on the base piece54. Numeral58inFIG. 11denotes a seam made of sewing thread or the like that joins the base piece54to the lower surface of the airbag12.

The base piece54has a slit60similar to the slit50of the airbag12and two bolt insertion holes62for the stud bolts20to pass through, which overlap concentrically with the bolt insertion holes12aof the airbag12, respectively. Opposite ends of the slit60also connect to the bolt insertion holes62, respectively. The arrangement, however, is not limited to that. For example, the slit60may be arranged remote from the bolt insertion holes62, as with the slit50. The width and the length of the slit60are also set as appropriate depending on the size of the gas generator14and the retainer16.

The cover56also has two bolt insertion holes64for the stud bolts20to pass through, which overlap concentrically with the bolt insertion holes62of the base piece54, respectively, when the cover56is folded on the base piece54. However, the cover56has no slits such as the slits50and60; when the cover56is folded on the base piece54, the respective slits60and50of the base piece54and the airbag12are closed with the cover56.

When the gas generator14and the retainer16are disposed inside the airbag12, first, the gas generator14is locked to the bracket30of the retainer16in advance. Referring toFIG. 11, the retainer16with the gas generator14is inserted into the airbag12through the slits60and50so as to expand the slit60of the base piece54of the cover cloth52and the slit50of the airbag12.

After the whole of the retainer16with the gas generator14has been inserted into the airbag12, the cover56of the cover cloth52is folded on the base piece54, in which case the contact surface of the cover56and the base piece54may be coated with a sealing member or the like. The stud bolts20are extended from the interior of the airbag12to the exterior through the respective bolt insertion holes12a,62, and64of the airbag12, the base piece54, and the cover56.

Thereafter, the first nuts24are tightened to the stud bolts20to join the airbag12and the retainer16together. At that time, the ground fabric of the airbag12and the base piece54and the cover56of the cover cloth52are clamped by the retainer16and the first nuts24, so that the cover56is brought into close contact with the base piece54to close the slits60and50. Accordingly, the gas from the gas generator14is prevented from flowing to the exterior of the airbag12through the slits50and60when the gas generator14is activated.

Although the above embodiment has the recess28in the bottom of the airbag module housing8d(seat pan8), for accommodating the patches22and the first nuts24, the recess may be provided at the lower surface of the retainer, as in the embodiment ofFIG. 7. Alternatively, the recess may be provided to both of the retainer and the seat pan, which are opposed to each other to form a space for accommodating the patches and the nuts.

An airbag module10A ofFIG. 7includes a retainer16A in the airbag12. The retainer16A is placed on the inner surface of the airbag12so as to push the lower part of the airbag12from the interior of the airbag12against the bottom of the airbag module housing8dof the seat pan8. Also in this embodiment, the stud bolts20project downward from the lower surface of the retainer16A. Each stud bolt20is passed through the bolt insertion hole (not shown inFIG. 7) in the lower part of the airbag12, to which the first nut24is tightened from the exterior of the airbag12through the patch22; thus, the airbag12is joined to the retainer16A.

The embodiment has no recess for accommodating the patches22and the first nuts24in the bottom of the airbag module housing8d; instead, it has a recess28A for accommodating the patches22and the first nuts24in the lower surface of the retainer16A.

Other arrangement of the occupant protection system including the airbag module10A is the same as that of the occupant protection system ofFIGS. 1 to 6; the same numerals ofFIG. 7as those ofFIGS. 1 to 6designate the same components.

In the occupant protection system ofFIG. 7, the patches22and the first nuts24which join the airbag12to the retainer16A are accommodated in the recess28A in the lower surface of the retainer16A. Accordingly, when the retainer16A is arranged in the airbag module housing8d, the retainer16A is brought into close contact with the bottom of the airbag module housing8dthrough the airbag12without the retainer16A being separated from the bottom of the airbag module housing8dby the distance corresponding to the thickness of the patches22and the first nuts24.

Providing the retainer with the recess for accommodating the patches and the nuts for joining the airbag, as in the occupant protection system ofFIG. 7eliminates the necessity of forming the recess in the seat pan, allowing the conventional seat pan without the recess to be used.

While the above-described embodiments use a plate-like retainer, the structure of the retainer is not limited to that.

For example, an airbag module10B ofFIG. 8uses a substantially box-shaped gas generator holder16B as retainer. This embodiment includes the gas generator14in the gas generator holder16B.

The gas generator holder16B has an open area16bon the top. A jet of gas from the gas generator14is issued upward through the open area16b.

The lower surface of the gas generator holder16B is flat. The gas generator holder16B is disposed in the airbag12, the lower surface of which is placed on the inner surface of the lower part of the airbag12. The stud bolts20project downward from the lower surface of the gas generator holder16B and extend to the exterior of the airbag12through bolt insertion holes (not shown) at the lower part of the airbag12. The first nuts24are tightened to the stud bolts20through the patch22, so that the airbag12is joined to the gas generator holder16B.

The embodiment has the recess28in the bottom of the airbag module housing8dof the seat pan8, for accommodating the patches22and the first nuts24. The width of the recess28is smaller than that of the gas generator holder16B. Accordingly, when the gas generator holder16B is disposed in the airbag module housing8d, the patches22and the first nuts24which project from the lower surface of the gas generator holder16B are accommodated in the recess28and the lower surface of the gas generator holder16B is brought into close contact with the bottom of the airbag module housing8dthrough the airbag12. Other structure of the occupant protection system ofFIG. 8is the same as that of the occupant protection system ofFIGS. 1 to 6.

The above-described embodiments use a bag-shaped enclosure that covers the entire folded airbag as the enclosure for covering the airbag so as to restrain the airbag in a folded condition. The structure of the enclosure, however, is not limited to that.

For example, an airbag12A of an airbag module10C ofFIG. 9(a) includes brackets40on the left and right opposite ends for joining the airbag12A to a seat pan (not shown) and openings18aon the left and right opposite ends of the enclosure18A for extending the brackets40outwards. Numeral40adenotes an insertion hole for a bolt (not shown) for fixing each bracket40to the seat pan.

An enclosure18B of an airbag module10D ofFIG. 9(b) is shaped like a tube surrounding the center of the length of the folded airbag12.

An enclosure18C of an airbag module10E ofFIG. 9(c) is shaped like a band wound around the intermediate of the length of the folded airbag12.

When the enclosures that are constructed to enclose the folded airbag are used, such as the enclosure18B ofFIG. 9(b) and the enclosure18C ofFIG. 9(c), the displacement of the enclosures can be prevented by arranging them such that the stud bolts projecting from the retainer pass through the enclosures or the enclosures are in contact with the stud bolts.

It is to be understood that the above-described embodiments are merely examples of the invention and the invention is not limited to those. For example, in the embodiments, the joining of the airbag to the retainer and the fixing of the retainer to the seat pan are made with common stud bolts. Alternatively, the stud bolt for joining the airbag to the retainer and the stud bolt for fixing the retainer to the seat pan may be provided separately. The means for joining the airbag to the retainer and the means for fixing the retainer to the seat pan are not limited to the stud bolt and the nut.