Abstract:
To provide an airbag device for improving integrity between the airbag and exterior parts of a vehicle body and which excels in applicability. An airbag device is provided with a case which accommodates an airbag and an inflator. A lid is provided for releasing a side of the case when the airbag deploys together with a lid cover for covering the lid.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2008-021052 filed on Jan. 31, 2008 the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an airbag device for a vehicle such as a motorcycle or four-wheeled vehicle. 
     2. Description of Background Art 
     There has been a motorcycle equipped with an airbag device. The airbag device includes an inflator, an airbag, and a module cover. The inflator and the airbag are accommodated in a casing provided on the vehicle body. The module cover openably covers a top opening of the casing, thereby hiding the inflator and the airbag. The module cover includes a tear line. When the airbag is deployed, the module cover is torn along the tear line to be forwardly opened by being pushed by the deploying airbag, thereby allowing the airbag to be deployed further. See, for example, JP-A No. 2007-69792. 
     In the above technique, however, the module cover makes up a vehicle body exterior, so that there can be cases where it is difficult to secure an exterior design integrity between the module cover and other exterior parts of the vehicle body. Furthermore, to allow the module cover to make up a vehicle body exterior while being capable of appropriate opening movement, it is necessary to design the module cover differently for different models of motorcycles. This reduces the applicability of the airbag device. 
     SUMMARY AND OBJECTS OF THE INVENTION 
     An object of the present invention is to provide an airbag device which, while excelling in applicability, can improve exterior design integrity between the airbag device and a vehicle body exterior. 
     According to an embodiment of the present invention, an airbag device is provided that includes a case  53  which accommodates an airbag  51  and an inflator  52  with a lid  62  which, when the airbag deploys, releases a side of the case. A lid cover  70  is provided for covering the lid. 
     Designing a lid cover which is to make up an exposed exterior part of a vehicle body requires consideration to be made to prevent sink lines from being formed on the lid cover and also to secure integrity, in terms of both material and exterior design, between the lid cover and other exterior parts of the vehicle body. The lid cover structured as in the above embodiment of the present invention, however, requires no such consideration to be made, so that the lid cover is only required to be capable of being released when the airbag is deployed. 
     According to an embodiment of the present invention, the lid cover makes up an exterior design of a vehicle. 
     It is, therefore, possible to form the lid cover using a material similar to that of other exterior parts of the vehicle body separately from the lid closely related with the deploying function of the airbag. 
     According to an embodiment of the present invention, the lid cover is structured to be easily released from a peripheral part (for example, the fixing seat  77  of the following embodiment) when the airbag deploys. 
     Therefore, the lid cover does not hinder the opening movement of the lid. 
     According to an embodiment of the present invention, the lid cover is provided with a fixture part for fixation to a peripheral part, the fixture part includes a fragile portion. 
     It is, therefore, possible, by adjusting the fragile portion, to adjust the way the lid cover opens when the lid is opened by the deploying airbag. 
     According to an embodiment of the present invention, the lid cover is forwardly openable along a forward direction of the vehicle. This allows the airbag to be deployed effectively. 
     According to an embodiment of the present invention, an exterior surface of the lid cover makes up a panel section  32   a  or top shell  32  are positioned rearward of a handlebar  43  and forward of a seat  27  of a motorcycle. 
     In this arrangement, the lid cover does not spoil the appearance of the conspicuous exterior portion of the motorcycle. 
     According to an embodiment of the present invention, the lid cover itself can be formed of an exterior member of the vehicle body. Therefore, unlike in cases where a lid is exposed on the vehicle body, the lid cover can be designed without giving consideration for the prevention of sink line generation or for securing integration, in terms of both material and exterior design, between the lid cover and other exterior parts of the vehicle. Namely, the lid cover is only required to be capable of being released when the airbag is deployed. Thus, integrity between the lid cover and other exterior parts of the vehicle can be easily secured without special consideration. Furthermore, the case and the lid can be commonly used for different models of motorcycles, enhancing the applicability of the airbag device. 
     According to an embodiment of the present invention, the lid cover can be formed of a material similar to that of other exterior parts of the vehicle body separately from the lid closely related with the deploying function of the airbag. This facilitates improving the external appearance quality of the motorcycle. 
     According to an embodiment of the present invention, the lid cover does not hinder the opening movement of the lid, so that the airbag can be deployed smoothly. 
     According to an embodiment of the present invention, it is possible, by adjusting the fragile portion, to adjust the way the lid cover opens when the lid is opened. That is, the fragile portion can be adjusted to allow the lid cover to open without fail. 
     According to an embodiment of the present invention, the airbag can hold the occupant. 
     According to an embodiment of the present invention, the lid cover does not spoil the appearance of the conspicuous exterior portion of the motorcycle, and allows the external appearance quality of the motorcycle to be improved. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a side view of a motorcycle according to an embodiment of the invention; 
         FIG. 2  is a plan view of the motorcycle according to the embodiment of the invention; 
         FIG. 3  is a perspective view of a front portion of the motorcycle according to the embodiment of the invention; 
         FIG. 4  is an exploded perspective view of an airbag device according to the embodiment of the invention; 
         FIG. 5  is a schematic front view of the airbag device according to the embodiment of the invention; 
         FIG. 6  is a schematic right side view of the airbag device according to the embodiment of the invention; 
         FIG. 7  is a schematic rear view of the airbag device according to the embodiment of the invention; and 
         FIG. 8  is a plan view of a lid according to the embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention will be described below with reference to drawings. The directions front, rear, left, and right referred to in the following description are as seen in the forward direction of the motorcycle unless otherwise specified. In the attached drawings, arrows FR, LH, and UP represent the forward, leftward, and upward directions, respectively, of the vehicle. 
     As shown in  FIGS. 1 to 3 , a front wheel  2  of a motorcycle  1  is journaled to a lower end portion of a pair of left and right front forks  3 . An upper portion of each of the front forks  3  is steerably connected, via a steering system  4 , to a head pipe  6  provided in a front end portion of a body frame  5 . A handlebar  43  for steering the front wheel is attached to an upper portion of the steering system  4 . A pair of left and right main frames  7  extend downwardly and rearwardly from the head pipe  6 . A water-cooled, 4-stroke, horizontally-opposed six-cylinder engine  10  as a prime mover for the motorcycle  1  is mounted below the main frames  7 . 
     A front end portion of a swing arm  11  to which a rear wheel  9  is journaled is swingably connected to a pivot plate  8  connected to a rear end portion of each of the main frames  7 . The swing arm  11  is of a hollow one-sided type, and the rear wheel  9  is journaled to a rear end portion thereof. A drive shaft, not shown, extending from the engine  10  is inserted through the one-sided swing arm. Power generated by the engine  10  is transmitted to the rear wheel  9  via the drive shaft and a gear box  12  disposed in a central portion of the rear wheel. 
     A front portion of a seat frame  14  supporting front and rear seats  27  and  28  for occupants is joined to near the pivot plate  8 . The front seat  27  is for a rider. The rear seat  28  is for a pillion passenger. The front seat  27  includes a front seat body  27   a  and a backrest  27   b . The rear seat  28  includes a rear seat body  28   a  and a seat back  28   b . The front and rear seat bodies  27   a  and  28   a  are integrally formed, and the backrest  27   b  is disposed between them. A rear trunk  29  is disposed behind the rear seat body  28   a . The seat back  28   b  is positioned in front of the rear trunk  29 . A fuel tank  30  and an air cleaner box  31  for cleaning intake air are disposed forwardly of the front seat  27  with the fuel tank  30  extending to below the front seat  27 . These parts are covered by a top shelter  32  which is an exterior part. 
     A large front cowl  34  provided with a pair of left and right headlamps  33  is disposed in a front body portion of the motorcycle  1 . A large windscreen  35  is provided above a front portion of the front cowl  34 . A meter panel  36  provided with, for example, a speedometer and a tachometer is disposed on a rear side of an upper portion of the front cowl  34 . The top shelter  32  extending downwardly and rearwardly of the meter panel  36  covers a motorcycle body portion ranging from the rear side of the front cowl  34  to the front seat  27 . Left and right mirrors  38  each provided with a front winker  37  are attached to both sides of an upper portion of the front cowl  34 . A radiator  39  for the engine is disposed laterally inwardly of the front cowl  34  (inwardly in the vehicle width direction), the radiator  39  being oriented approximately perpendicularly to the lateral direction of the motorcycle. 
     Left and right saddle bags  40  are disposed on both sides below the rear seat  28  and rear trunk  29 . Rear combination lamps  41  each of which functions as tail lamps, brake lamps, and rear winkers are disposed on both sides of a rear portion of the left and right saddle bags  40  and both sides of a rear portion of the rear trunk  29 . A muffler  42  for engine exhaust is disposed downwardly of each of the left and right saddle bags  40 . 
     The top shelter  32  is provided with an openable/closable shelter lid  44  disposed in front of the front seat  27 . The shelter lid  44  allows fuel to be fed to the internal fuel tank through a filler opening of the fuel tank. A panel section  32   a  is formed in front of the shelter lid  44  to be rearward of a handlebar  43  and forward of the front seat  27 . The panel section  32   a  has a cut-out portion  44   a  in which an airbag device  50  is disposed. Alternatively, the top shelter  32  may be provided with a depressed part, and the airbag device  50  may be disposed in the depressed part, or such a depressed part to accommodate the airbag device  50  may be provided in the panel section  32   a.    
       FIG. 4  is an exploded perspective view of the airbag device.  FIGS. 5 to 8  each show the airbag device schematically. As shown in  FIGS. 4 to 8 , the airbag device  50  has a case  53  which accommodates an airbag  51  and an inflator  52 . The case  53  is shaped like a rectangular box having an open top, left and right sidewalls  54 , front wall  55 , rear wall  56 , and bottom wall  57 . A bracket  58  to be fixed to the body frame  5  is fixed to each of the sidewalls  54 . The bracket  58  varies in type between different models of motorcycles. 
     Fixing holes  60  for rivets  80  are formed in an upper portion of each of the front wall  55 , rear wall  56 , and side walls  54 . The number of the fixing holes  60  formed in each of the front wall  55  and rear wall  56  is, for example, three. The number of the fixing holes  60  formed in each of the side walls  54  is, for example, two. Two pins  61  are provided in a lower portion of the front wall  55 . 
     The airbag  51  is made of, for example, nylon cloth. The inflator  52  is provided with an electric igniter, an ignition agent, and a nitrogen gas generating agent. The airbag  51  accommodated in the case  53  may be attached with one end of a belt member, not shown, the other end of which is attached to the vehicle body. In such an arrangement, when the airbag  51  is deployed, the belt member can keep the airbag  51  in an appropriate position. 
     The open top of the case  53  is fixedly covered by the lid  62  such that the lid  62  is released when the airbag  51  is deployed. The lid  62  is a rectangular member having an upper wall  63 , a front wall  64 , side walls  65 , and a rear wall  66 , the upper wall  63  being surrounded by the other walls. It has fixing holes  67  corresponding to the fixing holes  60  for the rivets  80  provided in the case  53 , i.e. three each of the fixing holes  67  in the front wall  64  and rear wall  66 , and two each in the side walls  65 . The upper wall  63  of the lid  62  includes a U-shaped tear line  68  formed of three portions with one portion extending along the rear wall of the lid  62  and the rest of two portions extending along the two side walls of the lid  62 . When the airbag  51  deploys, the U-shaped portion, i.e. an opening portion L, defined by the tear line  68  of the top wall  63  of the lid  62  is torn open along the tear line  68 , allowing the airbag  51  to be deployed outward. 
     A lid cover  70  is, like the top shelter  32  and panel section  32   a , a member to make up the exterior design of the motorcycle  1 , so that it is formed of, for example, a material similar to that of the panel section  32   a  to look harmonious with the panel section  32   a . The lid cover  70  has an upper wall  72  and a peripheral wall  73  surrounding the upper wall  72  and extending diagonally downwardly. The peripheral wall  73  is, in a front edge portion thereof, provided with a pair of downwardly extending guide bars  74 . The guide bars  74  each have a guide slot  75 . The pins  61  of the case  53  are inserted through the guide slots  75 , so that, when the airbag  51  is deployed, the lid cover  70  is guided to move upwardly. A peripheral portion of the peripheral wall  73  of the lid cover  70  is designed to cover a peripheral portion of the cut-out portion  44   a  of the top shelter  32  so that the cut-out portion  44   a  is not visible from the outside. 
     The peripheral wall  73  of the lid cover  70  has, in a middle portion of its rear edge, a fixture piece  71  having a screw hole  76 . The fixture piece  71  is fixed, with a screw  78 , to a fixing seat  77  provided on the vehicle body. In this arrangement, when the lid cover  70  is set in place, a distance D is secured between the lid cover  70  and the lid  62 . The distance D secures a space required to allow an initial opening movement of the opening portion L. 
     The fixture piece  71  includes a tear line  79  formed in a base portion thereof. When receiving a load from below in deployment of the airbag  51 , the fixture piece  71  is broken off along the tear line  79  and separated from the peripheral wall  73 . 
     When the fixture piece  71  is broken off the lid cover  70 , the lid cover  70  is allowed to move up, relative to the case  53 , being guided by the guide bars  74  and subsequently open forwardly (in the direction indicated by the arrows in  FIG. 3 ) being led by its rear edge. As a result, the airbag  51  is allowed to inflate outward. 
     According to the above embodiment, when a frontal collision of the motorcycle  1  is detected, the inflator  52  is caused, by an ignition current from an airbag controller, not shown, to generate, for example, nitrogen gas. The nitrogen gas enters the airbag  51  to deploy it. 
     When, in an initial stage of inflation of the airbag  51 , the lid  62  is pushed from below by the airbag  51  inflated in the case  53 , the upper wall  63  of the lid  62  is torn along the tear line  68 . This causes the opening portion L to forwardly open about a front portion thereof, allowing the airbag  51  to inflate outward. 
     As the airbag  51  further deploys causing the opening portion L of the lid  62  and the airbag  51  to push the lid cover  70  from the back side, the lid cover  70  is subjected to an upward force which eventually causes the fixture piece  71  of the lid cover  70  to be broken off along the tear line  79 . As a result, the fixture piece  71  is left attached only to the fixing seat  77  provided on the vehicle body, and the lid cover  70  is moved upward causing the pins  61  to relatively move along the guide slots  75  of the guide bars  74 . This causes the lid cover  70  to further open forwardly (in the direction indicated by the arrows in  FIG. 3 ) about a front end portion thereof, allowing the airbag  51  to further deploy. The airbag  51  thus deployed can absorb the forward displacement of the occupant. 
     The lid cover  70  is only required to be capable of being released, when the airbag  51  deploys, by being pushed by the lid  62 . Whereas the lid  62  including the tear line  68  is required to meet requirements in terms of its strength, rigidity, shape, and material so as to make the airbag  51  appropriately deployable, no such requirements are imposed on the lid cover  70 . Therefore, the shape of the lid cover  70  can be designed, as an exterior part of the motorcycle  1 , with higher flexibility; the lid cover  70  can be shaped not to cause the generation of sink lines; and the lid cover  70  can be formed of the same material as that of the panel section  32   a . Thus, the lid cover  70  can be easily designed to be harmonious with the vehicle body design. The case  53 , airbag  51 , inflator  52 , and lid  62  included in the airbag device  50  can be made common to different models of motorcycles. Therefore, to install the airbag device in different models of motorcycles, only the lid cover  70  and brackets  58  of the case  53  are required to be designed differently to suit different models of motorcycles. Thus, the airbag device has flexible applicability, being easily applicable to different models of motorcycles. 
     The lid cover  70  is, like the top shelter  32  and panel section  32   a , a member to make up the exterior design of the motorcycle  1 . Therefore, unlike the lid  62  that is closely related with the deploying function of the airbag  51 , the lid cover  70  can be formed of a material similar to that of the panel section  32   a  so as to improve the external appearance quality of the motorcycle. 
     The lid cover  70  can be easily broken along the tear line  79 , so that, when the airbag  51  is deployed, the lid cover  70  opens without fail not to hinder the deployment of the airbag  51 . 
     The present invention is not limited to the above embodiment. For example, the fixture piece  71  of the lid cover  70  may be fixed to the rear wall  66  of the lid  62 . 
     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.