Abstract:
An inflatable air-belt device including a shoulder belt and lap belt. When the air-belt is inflated, a tension is generated in the shoulder belt and is transferred to the lap belt so that both the shoulder belt and the lap belt adhere closely to an occupant. When an emergency condition is detected, an inflator is actuated to inflate a bag located in the shoulder belt creating a tension of more than a predetermined strength in the shoulder belt. The lap belt is drawn toward the shoulder belt to release a stopper located in a buckle positioned between the belts. The lap belt moves toward the shoulder belt through a hole located in the tongue of the buckle. A nozzle for receiving pressurized gas is inserted in a slit in the belts so that the lap belt may move smoothly toward the shoulder belt without obstruction.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to devices for protecting occupants of a movable body such as a vehicle especially during a collision involving the vehicle. In particular, the present invention relates to a device for restraining an occupant in the manner of a seatbelt and having an air-belt inflated by gas provided by a gas generator. 
     2. Description of the Related Art 
     In an air-belt device, at least a portion, especially the portion touching an occupant&#39;s body, of the webbing of a seatbelt device is implemented as an inflatable air-belt. When a collision or other emergency situation requiring protection of the occupant occurs, a gas generator is activated to inflate the air-belt. Japanese Unexamined Patent Publication No. 5-85301 and U.S Pat. No. 5,346,250, both of which are incorporated by reference herein, disclose an example of an air-belt device in which one end of an air-belt is connected to a tongue, and paths for gas are respectively disposed in the tongue and a buckle in which the tongue may be fitted, so that gas may be introduced into the air-belt via the paths. The other end of the air-belt is connected to a length of webbing identical to a conventional seatbelt device by sutures, and the length of webbing is wound onto a seatbelt retractor. A lap belt is formed of webbing identical to a conventional seatbelt and is connected to the tongue. When the air-belt is inflated by introduction of gas into the air-belt the length of the shoulder is shortened, creating a tension in the shoulder belt. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an air-belt device in which a portion of the tension generated in the shoulder belt is transferred to the lap belt while sufficient tension is applied to both the shoulder belt and the lap belt in order to protect and restrain the occupant. 
     An air-belt device according to the present invention comprises: an air-belt having a bag into which gas is introduced and a length of mesh webbing covering the bag; a tongue having a hole which the mesh webbing of the air-belt passes through; a buckle in which the tongue is mounted; a shoulder-side retractor for rolling up a shoulder-side end portion of the mesh webbing; a lap-side retractor for rolling up a lap-side end portion of the mesh webbing; a passage disposed in the buckle for carrying gas; and a gas-receiving means disposed in the tongue and connected to the bag positioned to mate with the passage when the tongue is mounted in the buckle, wherein a slit is formed in a side edge of the mesh webbing in the region of the hole in the tongue, and wherein the gas-receiving means is disposed in the slit. It is preferable that the slit in the webbing extend toward both the shoulder-side and the lap-side of the mesh webbing from the hole in the tongue. 
     In the air-belt device, the shoulder belt is drawn around the front portion of the upper half of an occupant body by mounting the tongue in the buckle. When a vehicle encounters an emergency such as a collision, gas is injected from the passage in the buckle into the bag via the gas-receiving means so as to inflate the bag and generate tension in the shoulder belt. The lap belt is drawn toward the shoulder belt to generate tension in the lap belt as well. A slit is formed in the length of mesh webbing of the air-belt. Because the gas-receiving means is inserted in the slit, when a tension is generated in the shoulder belt to draw the lap belt, the lap belt moves smoothly toward the shoulder belt through the hole in the tongue without obstruction. The gas-receiving means may be formed of a pipe-shaped nozzle to be connected to the tongue. It is preferable that the bag be connected to the rear end of the pipe-shaped nozzle. 
     According to the present invention, an air-belt device may further comprise a retaining member or stopper for securing the mesh webbing of the air-belt to the tongue. The retaining member may be located adjacent the hole in the tongue and may be released by when a predetermined force of more is exerted on the mesh webbing of the air-belt thereby allowing the webbing to pass freely through the hole in the tongue. 
     According to the present invention, the internal surface of the mesh webbing and the bag may be bonded together. Preferably the bonding releases when the bag is inflated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing an air-belt device according to an embodiment of the present invention. 
     FIG.  2 ( a ) is a schematic representation of the connection between the air-belt and the tongue shown in FIG.  1 . 
     FIG.  2 ( b ) is a schematic representation of a gas receiving nozzle and an inflatable bag for the air belt device of FIG.  1 . 
     FIG.  3 ( a ) is a schematic representation showing the connection between the air-belt and the tongue shown in FIG.  2 ( a ) in an inflated state. 
     FIG.  3 ( b ) is a schematic representation of the gas receiving nozzle and the inflatable bag shown in FIG.  2 ( a ) in an inflated state. 
     FIG.  4 ( a ) is a perspective view of the stopper. 
     FIG.  4 ( b ) is a perspective view of the stopper of FIG.  4 ( a ) in a separated state. 
     FIG. 5 is a partially cutaway schematic view showing the bonding layer connecting the inflatable bag to the mesh webbing of the air belt. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an air-belt device according to the present invention; FIG.  2 ( a ) is a plan view of the connecting portion between an air-belt and a tongue; FIG.  2 ( b ) is a perspective view showing a bag and a nozzle in the connecting portion; FIGS.  3 ( a ) and  3 ( b ) are perspective views of the same portions as in FIGS.  2 ( a ) and  2 ( b ) in an inflated state; FIG. 4 includes perspective views of a retaining member; and FIG. 5 is a perspective view showing an internal structure of the air-belt. 
     As shown in FIG. 1, the air-belt  1  comprises mesh webbing  7  including a shoulder belt  2  and a lap belt  3 , a buckle  4  disposed in a vehicle body (e.g. in the floor of the vehicle), a tongue  5  to be inserted and retained in the buckle  4  during belt mounting, and a shoulder anchor  6  for guiding the shoulder belt  2 . 
     The shoulder belt  2  and the lap belt  3  are integrally formed from the mesh webbing  7 . The shoulder belt  2  is preferably connected to a seat belt retractor  12  that includes an emergency locking mechanism. This type of retractor commonly is referred to as an “Emergency Locking Retractor” or ELR. The retractor may be fixed to the vehicle body. The shoulder belt  2  is wound or rolled up in the retractor  12  after being slidably inserted through the shoulder anchor  6 . The shoulder belt  2  is drawn across the front surface of the upper half of an occupant&#39;s body. The lap belt  3  drawn around the front surface of the occupant&#39;s waist and is would or rolled up in an ELR type seat belt retractor  13  fixed to the vehicle body. 
     The air belt also may include a bag  8  disposed in the mesh webbing  7 , and a nozzle  9  connected to the bag  8  and secured to the tongue  5 . An inflator  10  is connected to the buckle  4  for generating high pressure gas when it is actuated by an emergency situation such as a vehicle collision. A sensing device (not shown) detects the occurrence of an emergency situation to activate the inflator  10 . A cylindrically shaped passage  11  as a gas-injecting portion is disposed in the buckle  4  for injecting and guiding the gas provided by the inflator  10  to the nozzle  9 . When the tongue  5  is mounted in the buckle  4 , the front end of the nozzle  9  opposes and mates with the passage  11 . 
     A hole  15  is provided in the tongue  5 . The mesh webbing passes through the hole  15 . The tongue  5  also may include a stopper (i.e. a retaining member)  16  for preventing the webbing passing through hole  15  from moving in the longitudinal direction. The stopper  16  may comprise two half pieces  17 ,  18 , as shown in FIG. 4, for example. The first half-piece  17  includes a protrusion  17   a  and the second half-piece  18  includes a recessive hole  18   a . The half-pieces  17  and  18  are positioned on opposite sides of the tongue  5 . The protrusion  17   a  is tightly inserted into the recessive hole  18   a , so that the halfpieces  17  and  18  are connected together to pinch the webbing  7  of the air-belt therebetween, thereby preventing the webbing  7  from moving freely within the hole  15 . When the bag  8  is inflated a tensile force is generated in the shoulder belt  2 . When the force exceeds a predetermined value, the half-pieces  17  and  18  separate from each other permitting the air-belt  1  to move freely through the hole  15 . 
     A slit  20  is formed in the length of mesh webbing  7  along a side edge of the air-belt between the shoulder belt  2  and the lap belt  3  and passing through the hole  15 . The slit  20  extends from the tongue  5  in the direction of the shoulder belt  2  approximately 20 to 50 mm and from the tongue  5  in the direction of the lap belt  3  approximately 50 to 100 mm. Both ends of the slit  20  are securely sewed so that the mesh webbing  7  closes the slit  20  thereby preventing the split from spreading or increasing in length. 
     As shown in FIG. 2, the nozzle  9  passes through the slit  20 . The nozzle  9  may be formed of a bent pipe in a roughly S-shape and fixed to the tongue  5  by a bracket  19  integrally formed with the nozzle  9 . The nozzle  9  may be fixed to the tongue  5  by riveting, for example, through a hole  21 . The rear end of the nozzle  9  is fitted into the end of the bag  8  and the bag  8  may be hermetically and securely joined to the nozzle  9  with a clamping band  22 . 
     The bag  8  is formed of a material impermeable or scarcely permeable by gas (e.g. resin coated cloth) in an elongated shape. The bag may be folded into a slender belt. The bag  8  is folded twice in the direction orthogonal to the longitudinal direction of the shoulder belt  2  to form an additional or overlapping portion  25  as shown in FIG.  2 ( b ). The stress applied to a connecting portion between the bag  8  and the nozzle  9  is eased by forming the overlapping portion  25 . The overlapping portion  25  is unfolded to allow the bag to straighten when the bag  8  is inflated as shown in FIG.  3 ( b ). 
     The mesh webbing  7  covering the folded belt bag  8  comprises a flat and hollow belt. The mesh webbing  7  is formed of knit fabric, which has limited elasticity in the longitudinal direction but is more supple and may be stretched along its width or radial direction. 
     The inner surface of the length of mesh webbing  7  and the bag  8  may be bonded together with a bonding layer  23  as shown in FIG.  5 . The bonding layer  23  is preferably formed of a suitable adhesive or a bonding agent. Alternatively, the length of mesh webbing  7  and the bag  8  may be joined together by fusion. The inner surface of the mesh webbing  7  and the bag  8  are joined together in such a manner, so that the inner surface of the mesh webbing  7  and the outer surface of the bag  8  cannot slip relative to each other. As a result of the bonding between the bag  8  and the shoulder belt  2 , the shoulder belt  2  may be easily handled. The bonding between the inner surface of the length of mesh webbing  7  and the bag  8  is released by exfoliation, etc., when the bag  8  is inflated. The separation of the bag from the webbing  7  allows the bag to inflate without being restricted by the mesh webbing  7 . 
     The air-belt device formed as above is used for protecting an occupant of a vehicle when the tongue  5  is secured into the buckle  4 . When the inflator  10  is not actuated, the air-belt  1  restricts an occupant to the seat in the same manner as an ordinary seat belt device. When the bag  8  is not inflated, the shoulder belt  2  is flat. 
     When the tongue  5  is mounted in the buckle  4 , and the inflator  10  is actuated (e.g. by a collision involving the vehicle). Gas is introduced into the bag  8  from the gas-injecting passage  11  through the nozzle  9 . As the bag inflates, the shoulder belt  2  radially expands into a thick cylindrical shape. One end of the shoulder belt  2  rolls up within the ELR  12  thereby preventing the shoulder belt from unrolling and lengthening during the collision. Therefore, the length of the mesh webbing  7  forming the shoulder belt  2  is reduced by the radial expansion of the shoulder belt  2 , and a tensile force exceeding a predetermined amount of tensile force is generated in the shoulder belt  2 . The excessive force on the webbing causes the stopper  16  to be released allowing the lap belt  3  to move through the hole  15  toward the shoulder belt  2 . The positioning of the nozzle  9  within the slit  20  allows the lap belt  3  to move smoothly toward the shoulder belt  2  without obstruction by the nozzle  9 . The tension generated in the shoulder belt  2  is thereby transferred to the lap belt  3 , so that the air-belt  1  is tightened as a whole to fit an occupant and restrict the occupant firmly to the seat. 
     The bag  8 , the nozzle  9  and/or the buckle  4  may include vent holes (not shown) for venting the gas in the bag  8 . When the upper half of the occupant body leans over the inflated shoulder belt  2 , the gas may flow gradually out of the bag through the vent holes so that the impact applied to the occupant is absorbed. 
     As described above, according to the present invention, when the air-belt is inflated, the tension generated in the shoulder belt is transferred to the lap belt as well, so that both the shoulder belt and the lap belt adhere closely to the occupant. The priority document, Japanese Patent Application No. H11-63499, filed Mar. 10, 1999, is incorporated by reference herein.