Airbag apparatus for a small size vehicle

[0001] The present nonprovisional application claims priority under 35 USC 119 to Japanese Patent Application No. 2002-103391 filed on Apr. 5, 2002 the entire contents thereof is hereby incorporated by reference.

[0002] 1. Field of the Invention

[0003] This invention relates to an airbag apparatus for a small size vehicle that includes an airbag, which can constrain a driver on a seat from moving forwardly through inflation expansion.

[0004] 2. Description of Background Art

[0005] Conventionally, a representative example of an airbag apparatus of the type described is disclosed in, for example, Japanese Patent Laid-open No. Hei 9-328053. According to the airbag apparatus, it is possible that the gas in the airbag is completely exhausted after a primary collision. If this occurs, then the constraint of the driver may become insufficient and the airbag may be kept in a half inflated state.

[0006] With the conventional airbag apparatus described above, however, a pressure regulation valve for keeping the airbag in a half inflated state is required, and the number of parts is great.

[0007] Further, where a conventional airbag apparatus is applied to such a motorcycle of a large size as shown in FIG. 5, in order to make the constraint of the driver reliable, not only it is necessary to increase the inflation expansion capacity of the airbag 19′ so that the airbag 19′ is expanded to a greater range, but also it is necessary to increase the amount of gas to be blown into the airbag 19′ and also the size of some other components such as an inflator is increased.

[0008] It is an object of the present invention to provide an airbag apparatus for a small size vehicle wherein an increase of the number of parts is prevented and miniaturization of the apparatus is achieved while constraining a driver on a seat.

[0009] In order to attain the object described above, an airbag apparatus for a small size vehicle which includes an airbag which can constrain a driver on a seat from forward motion through an inflation expansion. The airbag includes a main bag portion and an auxiliary bag portion communicating with the inside of the main bag portion through a connecting hole, and the auxiliary bag portion is inflated and expanded with gas exhausted from the main bag portion through the connecting hole.

[0010] According to the configuration of the present invention, upon inflation expansion of the airbag, the main bag portion is inflated and expanded first and then the auxiliary bag portion is inflated and expanded with gas exhausted from the main bag portion through the connecting hole and the force of the driver pushing the main bag portion. Consequently, while the amount of gas to be blown into the airbag can be set to a comparatively small amount necessary only for an inflation expansion of the main bag portion, the airbag can be expanded to a comparatively great range by the main bag portion and the auxiliary bag portion. Further, since a part for exclusive use for expanding the airbag to a great extent is not required, an increase in the number of parts can be prevented and miniaturization of the apparatus, particularly miniaturization of the inflator, can be achieved while constraining the driver on the seat.

[0011] Further, according to the present invention, the airbag apparatus for a small size vehicle includes an exhaust hole having a smaller diameter than that of the connecting hole in the auxiliary bag portion. According to the configuration just described, gas can be circulated smoothly from the main bag portion to the auxiliary bag portion, and an inflation expansion of the auxiliary bag portion after inflation expansion of the main bag portion can be made reliable.

[0012] Furthermore, according to the present invention, the airbag apparatus for a small size vehicle includes at least a portion of the airbag which can contact with the driver on the seat that is formed from a material having a high coefficient of friction. Thus, the constraining effect of the driver by the airbag can be further promoted.

[0013] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

[0022] In the following, an embodiment of the present invention is described based on a working example of the present invention as illustrated in FIGS. 1 to 4.

[0023] Referring first to FIG. 1, a front fork 7 is supported for a steering motion on a head pipe 6 provided at a front end of a body frame 5 of the motorcycle, and a front wheel WF is supported for rotation at a lower end of the front fork 7 while a steering handle bar 8 is connected to an upper portion of the front fork 7. Further, a swing arm 9 is supported for upward and downward rocking motion at a rear portion of the body frame 5, and a rear wheel WR is supported for rotation at a lower end of the swing arm 9.

[0024] A dummy tank 10 is carried at a front half portion of the body frame 5 and is formed in a shape the same as that of a conventional fuel tank. A seat rail 11 is provided at a rear end portion of the body frame 5, and a seat 12 of the tandem type is disposed rearwardly of the dummy tank 10 for upward and downward motion on the seat rail 11.

[0025] Most of the parts of the body frame 5 are covered with a body cover 15 made a synthetic resin and composed of a front cowl 13 and a rear cowl 14.

[0026] Referring also to FIG. 2, an accommodation recess 16 is provided at a rear portion of the dummy tank 10 such that it is open upwardly. An airbag module 17 of the airbag module is accommodated in the accommodation recess 16.

[0027] The airbag module 17 includes an airbag housing 18, an airbag 19 accommodated in the airbag housing 18, and an inflator 20 for generating gas for inflating and expanding the airbag 19.

[0028] The airbag housing 18 is formed in a cup shape from a light material such as a synthetic resin material and has an accommodation tubular portion 18a for being accommodated in the accommodation recess 16 such that the airbag 19 can be accommodated therein in a folded state. A lid portion 18b is provided for closing an upper end opening of the accommodation tubular portion 18a. The airbag housing 18 is attached at a lower portion of the accommodation tubular portion 18a thereof to the dummy tank 10 by mounting pieces 21 secured to the dummy tank 10.

[0029] The lid portion 18b is connected to the accommodation tubular portion 18a through a hinge portion 18c disposed at a location around the lid portion 18b, for example, at a location on the opposite side to the seat 12 and a fragile portion 18d disposed at a portion of the periphery of the lid portion 18b except the hinge portion 18c. The fragile portion 18d is formed such that it can be broken readily.

[0030] The airbag 19 includes a main bag portion 19a formed as a bag having an opening 22 at a lower face thereof and an auxiliary bag portion 19b communicating with the inside of the main bag portion 19a through a connecting hole 23. An exhaust hole 24 is provided in the auxiliary bag portion 19b.

[0031] The connecting hole 23 introduces gas exhausted from the main bag portion 19a therethrough to inflate and expand the auxiliary bag portion 19b, and the exhaust hole 24 is formed with a diameter smaller than that of the connecting hole 23.

[0032] At least a portion of the airbag 19 that can contact with a region of the driver positioned on the seat 12, except for the driver's face or head, is formed from a material having a high coefficient of friction such as rubber or a coarse material. FIGS. 6 and 7 are schematic showings of the portion of airbag 19 formed of material 19h having a high coefficient of friction.

[0033] The airbag 19 is accommodated in a folded state in the airbag housing 18. Meanwhile, the inflator 20 is supported by a mouse ring 25a securely attached to the opening 22 on the lower face of the airbag 19, the airbag 19 being accommodated in the airbag housing 18 which is supported fixedly to the mounting pieces 21 secured to the dummy tank 10.

[0034] An impact detection sensor (not shown) such as an acceleration sensor is attached to the body frame 5. In response to detection of an impact higher than a predetermined value by the impact detection sensor, the inflator 20 operates to supply high pressure gas into the airbag 19.

[0035] In addition, a baggage accommodation box 25 (refer to FIG. 1) is provided at a portion of the dummy tank 10 except for the location wherein the airbag module 17 is disposed. By opening or closing a lid (not shown) provided for opening and closing movement on the dummy tank 10, baggage can be placed into and removed from the baggage accommodation box 25.

[0036] Subsequently, operation of the present working example is described. The airbag 19 includes the main bag portion 19a and the auxiliary bag portion 19b communicating with the inside of the main bag portion 19a through the connecting hole 23. The auxiliary bag portion 19b is inflated and expanded with gas exhausted from the main bag portion 19a through the connecting hole 23.

[0037] Accordingly, when the inflator 20 operates in response to the detection of an impact higher than the predetermined value by the impact detection sensor upon collision or the like and high pressure gas is supplied into the airbag 19, first the main bag portion 19a of the airbag 19 breaks the fragile portion 18d of the airbag housing 18 and inflates upwardly in an instant while opening the lid portion 18b as shown in FIGS. 3 and 6. Consequently, the driver positioned on the seat 12 is constrained from forward motion by the inflated and expanded main bag portion 19a.

[0038] Then, the auxiliary bag portion 19b is inflated and expanded as shown in FIGS. 4 and 7 by gas exhausted from the main bag portion 19a through the connecting hole 23 and the force pushing the main bag portion 19a by the driver. Consequently, while the amount of gas to be blown into the airbag 19 can be set to a comparatively small amount only necessary for inflation expansion of the main bag portion 19a, the airbag 19 can be expanded to a comparatively great range by the main bag portion 19a and the auxiliary bag portion 19b.

[0039] Upon an inflation expansion of the airbag 19, the main bag portion 19a is inflated and expanded first and then the auxiliary bag portion 19b is inflated and expanded with gas exhausted from the main bag portion 19a through the connecting hole 23 in this manner. While the amount of gas to be blown into the airbag 19 from the inflator 20 can be set to a comparatively small amount necessary only for inflation expansion of the main bag portion 19a, the airbag 19 can be expanded to a comparatively greater range by the main bag portion 19a and the auxiliary bag portion 19b. Further, since a part for exclusive use for expanding the airbag 19 to a great extent is not required, an increase in the number of parts can be prevented and miniaturization of the apparatus, particularly miniaturization of the inflator 20, can be achieved while constraining the driver on the seat 12.

[0040] Further, since the exhaust hole 24 having a diameter smaller than that of the connecting hole 23 which interconnects the main bag portion 19a and the auxiliary bag portion 19b is provided in the auxiliary bag portion 19b, gas can be circulated smoothly from the main bag portion 19a to the auxiliary bag portion 19b and inflation expansion of the auxiliary bag portion 19b after inflation expansion of the main bag portion 19a can be made reliable.

[0041] Furthermore, since at least a portion of the airbag 19 that can contact with a region of the driver on the seat 12, except for the driver's face or head, is formed from a material having a high coefficient of friction, the constraining effect of the driver by the airbag 19 can be further promoted.

[0042] While the working example of the present invention is described above, the present invention is not limited to the working example described above and various design alterations can be made without departing from the present invention recited in the claims.

[0043] Further, the present invention can be applied widely not only to a motorcycle of the working example described above but also to small size vehicles such as a scooter type motorcycle or a motor tricycle.

[0044] As described above, according to the present invention, an increase in the number of parts can be prevented and miniaturization of the apparatus, particularly miniaturization of the inflator, can be achieved while constraining the driver on the seat.

[0045] Further, gas can be circulated smoothly from the main bag portion to the auxiliary bag portion and inflation expansion of the auxiliary bag portion after an inflation expansion of the main bag portion can be made reliable.

[0046] Furthermore, the constraining effect of the driver by the airbag can be further promoted.

[0047] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.