Vehicle occupant side crash protection system

[0002] Reference should be made to the following commonly assigned prior patents (copending patent applications), and the contents of these patents (patent applications) are hereby incorporated in this application by reference.

[0003] The present invention relates to a vehicle occupant protection system, and in particular to a vehicle occupant protection system for protecting the vehicle occupant from the impact of a side crash.

[0004] In recent years, to the end of improving the protection of the occupant of a motor vehicle from the impact of a side crash, various vehicle body structures have been proposed which minimize the deceleration of the passenger compartment and prevent the deformation of the vehicle body from reaching the passenger compartment by appropriately controlling the deformation mode of the part (crushable zone) of the vehicle body other than the passenger compartment (see Japanese patent laid open publication No.7-101354).

[0005] According to such a conventional vehicle body structure, the crushable zone for absorbing the impact of a frontal crash can be provided by the length of the engine room, but the crushable zone for the impact of a side crash cannot be adequately provided by the thickness of the door. Therefore, it has been practiced to provide a reinforcing bar inside the door to prevent the deformation of the door from affecting the passenger compartment as a measure against a side crash.

[0006] However, because such a conventional measure against a side crash is based on the prevention of the deformation of the door so as to prevent the door from intruding into the passenger compartment, it inevitably detracts from the absorption of the impact acting upon the vehicle body, and is unable to adequately prevent the vehicle occupant from moving toward the door under the acceleration acting on the vehicle body.

[0007] In view of such problems of the prior art, a primary object of the present invention is to provide a vehicle occupant protection system which can favorably control the impact to the vehicle occupant at the time of a side crash.

[0008] A second object of the present invention is to provide a vehicle occupant protection system which prevents the vehicle occupant from colliding with the door at the time of a vehicle side crash.

[0009] A third object of the present invention is to provide a vehicle occupant protection system which can be fitted within a limited available space around the seat of the vehicle occupant.

[0010] According to the present invention, such objects can be accomplished by providing a vehicle occupant protection system, comprising a seat fitted with a seat belt for restraining a vehicle occupant and laterally moveably supported by a floor, said seat belt having two ends attached to the seat; a crash load input member having a higher rigidity than the vehicle body, the crash load input member being connected to the seat and having one end extending to a part adjacent to a side sill; and brake means for applying an opposite force to the seat after it has traveled a certain distance toward the central part of the vehicle body.

[0011] Thus, the crash load input member having a higher rigidity than the vehicle body causes the acceleration acting on the seat to rise before the acceleration acting on the vehicle body does during an early phase of a vehicle crash. Thereafter, the velocity (deceleration) of the seat is equalized to that of the vehicle body during an intermediate phase of the vehicle crash by the brake means. This favorably controls the maximum level of acceleration acting upon the vehicle occupant. The maximum level of acceleration determines the degree of the injury which the vehicle occupant sustains at the time of a vehicle side crash. Furthermore, the seat moves toward the central part of the vehicle body or away from the door panel before the side panel of the vehicle body is pushed into the passenger compartment so that an enlarged space is created between the vehicle occupant and vehicle body. This prevents the injury to the vehicle occupant that could be caused by the collision with the vehicle door panel intruding into the passenger compartment.

[0012] The crash load input member may have an inboard end attached to the seat and an outboard end located at a side part of the vehicle body, such as a part adjacent to the side sill, where an impact from a side crash is substantially directly transmitted. For a favorably controlled action of the crash load input member, it may be slidably supported by the upper or lower surface of the floor by using an appropriate slide bearing.

[0013] The seat is preferably provided with a restraining member for restraining the vehicle occupant from moving outwardly with respect to the seat so that the vehicle occupant may be held firmly to the seat and experience the designed time history of acceleration according to the present invention. The restraining member may consist of an armpit belt passed around an upper part of the vehicle occupant and/or an extension of a seat back extending forward from an outboard side thereof.

[0014] The brake means may consist of a power actuator, but more preferably consists of a member adapted to undergo a controlled deformation by a part of the seat as it travels toward the central part of the vehicle body. Such a member provides the required braking action in a more economical and simple manner.

[0015] To achieve the necessary motion of the vehicle seat at the time of a side crash without interfering with the existing arrangement for the fore-and-aft adjustment of the vehicle seat, the seat may be supported by the floor via a laterally extending rail which is in turn guided by a longitudinally extending rail attached to the floor for a fore-and-aft adjustment of the seat. In such a case, the power actuator may be attached to the floor if its working end is connected to the seat via a coupling for accommodating the fore-and-aft adjustment of the seat.

[0016] Now the present invention is described in the following with reference to the appended drawings, in which:

[0017] FIG. 1 is a schematic front view showing the structure of a vehicle occupant protection system embodying the present invention;

[0018] FIG. 2 is a schematic side view showing the structure of the vehicle occupant protection system embodying the present invention;

[0019] FIG. 3 is a view similar to FIG. 1 showing an early phase of the operation of the system of the present invention;

[0020] FIG. 4 is a view similar to FIG. 1 showing an intermediate phase of the operation of the system of the present invention;

[0021] FIG. 5 is a view similar to FIG. 1 showing a final phase of the operation of the system of the present invention;

[0022] FIG. 6 is a perspective view of an alternate arrangement for the seat; and

[0023] FIG. 7 is a horizontal sectional view of the seat back of the seat illustrated in FIG. 6.

[0024] FIGS. 1 and 2 show a vehicle occupant protection system for a vehicle side crash embodying the present invention. This vehicle occupant protection system comprises a seat 2 incorporated with a seat belt for restraining a vehicle occupant 1 seated in the seat, a pair of lateral slide rails 3 for supporting the seat in a laterally slidable manner, a crash load input bar 6 attached to a bottom part of the seat and laterally slidably supported by a lower surface of the floor 4 via a slide bearing 5, and a collapsible tube 7 for a braking action provided opposite to an inboard end surface of the crash load input bar 6 defining a gap having a prescribed dimension (A).

[0025] The lateral slide rails 3 are directly connected to the lower surface of the seat 2, and are provided with an appropriate retaining mechanism (not shown in the drawing) for normally retaining the seat 2 immobile at an initial position.

[0026] The lateral slide rails 3 are supported above the floor via a pair of longitudinal slide rails 8 provided with a suitable locking arrangement for adjusting the fore-and-aft position of the seat 2 according to the build of the vehicle occupant or the choice of the vehicle occupant. The longitudinal slide rails 8 of this embodiment consist of a per se conventional arrangement, and are fixedly attached to the floor 4.

[0027] The crash load input bar 6 extends between a centrally lower part of the seat 2 and the inboard surface of the side sill 9, and a side bumper 10 is attached to the outer end of the crash load input bar 6.

[0028] A longitudinal bar 11 having a T-shaped cross section is integrally attached to the lower surface of the seat 2, and is engaged by a U-shaped retaining part 12 which is integrally attached to the inboard end of the crash load input bar 6 so that this arrangement would not interfere with the fore-and-aft adjustment function for the seat 2.

[0029] The collapsible tube 7 is, for instance, made of a thin-walled steel tube, and is provided with a base end fixedly attached to the upper surface of the floor 4. The property and dimensions of the collapsible tube 7 are determined so that the collapsible tube 7 undergoes a plastic deformation, and produces a prescribed reaction load when hit by the inner end of the crash load input bar 6 (retaining part 12).

[0030] The seat 2 is provided with an outer shoulder anchor 13 attached to the seat back 2badjacent to the door, a shoulder belt 15 extending between the outer shoulder anchor 13 and a buckle 14 attached to the seat bottom adjacent to the central part of the vehicle body, an inner shoulder anchor 16 attached to the seat back 2badjacent to the central part of the vehicle body, an armpit belt 17 extending between the inner shoulder anchor 16 and the buckle 14, a retractor 18 attached to the seat bottom adjacent to the door, and a lap belt 19 extending between the retractor 18 and the buckle 14. The shoulder belt 15 and lap belt 19 perform the function of retaining the upper part of the vehicle occupant 1 against the deceleration of the vehicle occupant at the time of a frontal crash in a similar manner as a conventional three-point seat belt, and the armpit belt 17 mainly performs the function of retaining the upper part of the vehicle occupant against the acceleration of the vehicle body at the time of a side crash.

[0031] The mode of operation of the illustrated embodiment of the present invention is described in the following with reference to FIGS. 3 to 5.

[0032] When a side of a vehicle body (door) B is hit by another vehicle E, the kinetic energy of the other vehicle produces a lateral acceleration of the vehicle body B in the traveling direction D of the other vehicle E (see FIG. 3). At the same time, a crash load is applied to the side bumper 10 provided on the outer end of the crash load input bar 6 (see FIG. 3). The deformation of the crash load input bar 6 having a higher rigidity than the vehicle body B causes the crash load input bar 6 to move laterally toward the central part of the vehicle body B at a higher acceleration than the vehicle body B which absorbs the crash load as it deforms. The inboard movement of the crash load input bar 6 laterally inwardly accelerates the seat 2 which is substantially directly connected to the crash load input bar 6 along with the crash load input bar 6 (see FIG. 4).

[0033] Meanwhile, the vehicle occupant 1 in the seat 2 is somewhat delayed in accelerating inward because of its own inertia with respect to the seat which accelerates toward the center of the vehicle body. But, a tension is produced in the armpit belt 17 passed around the upper part of the vehicle occupant, and the armpit belt 17 restrains the upper part of the vehicle occupant from moving toward the door.

[0034] As the crashing vehicle E advances further into the vehicle body B, the seat 2 moves further toward the central part of the vehicle body by being pushed by the crash load input bar 6, and the inner end of the crash load input bar 6 eventually abuts the free end of the collapsible tube 7. Abutting of the inner end of the crash load input bar 6 moving inward toward the central part of the vehicle body along with the seat 2 causes a plastic deformation of the collapsible tube 7, and the resulting reaction load causes a deceleration to the seat 2 or a force directed opposite to the traveling direction D of the vehicle E (see FIG. 5).

[0035] Thus, the tension property of the armpit belt 17, the stress property of the collapsible tube 7 and the dimension of the gap (A) are determined in such a manner that the seat 2 decelerates as it moves toward the central part of the vehicle body and upon completion of the movement of the seat the velocity (deceleration) of the vehicle occupant coincides with the speed (deceleration) of the vehicle body B.

[0036] Once the deformation stroke of the collapsible tube 7 has been exhausted and the movement of the seat 2 toward the central part of the vehicle body has been completed, the deformation of the door and side sill may continue as they are pushed by the colliding vehicle E, but because the vehicle occupant 1 is held integrally with the seat 2 and vehicle body B, the acceleration acting upon the vehicle occupant can be kept sufficiently low, if the vehicle structure is designed in such a manner that the reaction load produced by the vehicle body B remains constant until immediately before the vehicle comes to a complete stop. Furthermore, because the seat 2 has already moved to a position adjacent to the central part of the vehicle body before the deformation of the door into the passenger compartment starts, and a relatively wide space is provided between the vehicle occupant and the inner surface of the door, the injury to the vehicle occupant which could be caused by the collision with the door can be substantially reduced. For the principle of controlling the maximum acceleration acting on the vehicle occupant, reference should be made to the prior patents (patent applications) mentioned above which are directed to the arrangement for reducing the impact of a frontal crash on the vehicle occupant.

[0037] As a means for restraining the lateral movement of the vehicle occupant, instead of using an armpit seat belt 17, the seat back 2bmay be provided with an extension 2cextending forwardly therefrom so as to wrap around the shoulder of the vehicle occupant 1 from sideways as shown in FIGS. 6 and 7.

[0038] Thus, according to the present invention, the impact acting on the vehicle occupant at the time of a vehicle crash can be substantially reduced by accelerating the seat to which the vehicle occupant is restrained in the traveling direction of the oncoming vehicle during an early phase of the crash, and decelerating the seat so as to reduce the difference in speed between the vehicle body and vehicle occupant during an intermediate phase of the crash. This, combined with the increase in the space between the door and vehicle occupant by moving the seat toward the central part of the vehicle body so as to prevent the vehicle occupant from hitting the door, makes a substantial contribution in improving the protection of the vehicle occupant at the time of a side crash.

[0039] Although the present invention has been described in terms of a preferred embodiment thereof, it is obvious to a person skilled in the art that various alterations and modifications are possible without departing from the scope of the present invention which is set forth in the appended claims.