Abstract:
An inflator which can be easily and simply manufactured without disassembly. The inflator includes a bottle connected to a diffuser. The bottle includes projections and key grooves formed on its periphery. The projections extend in the peripheral direction and the grooves extend in the axial direction. The diffuser includes guide groves on its inner periphery for guiding the projections of the bottle when the diffuser and the orifice member are coupled with each other. The diffuser also includes grooves which mate with the projections either component rotates, and key grooves which align with the key grooves of the bottle. Keys are inserted into the key grooves to prevent the bottle and the diffuser from rotating.

Description:
BACKGROUND  
         [0001]    The present invention relates to an inflator which generates gas for inflating and extending an airbag.  
           [0002]    There are several types of inflators, which generate gas for expanding airbags, such as a combustion type, a stored-gas type, and a hybrid type. The combustion type inflates an airbag with combustion gas which is generated by chemical reaction started by combustion of a gas-generating agent (propellant). The stored-gas type ejects a high-pressure gas stored in a container. The hybrid type, in which a gas-generating agent and a high-pressure gas are used in combination, generates gas for inflation by mixing a gas generated by the combustion of the gas-generating agent with the high-pressure gas.  
           [0003]    In FIG. 4, a stored-gas-type inflator is shown. FIG. 4 is a schematic longitudinal-sectional view of the stored-gas-type inflator. As shown in FIG. 4, an inflator  100  includes a bottle  101  to be charged with a high-pressure gas, and a sleeve (receiving member)  103  for receiving a perforation structure. A sealing plate  107  is fixed by welding to an orifice  1   05  of the bottle  101 . The sealing plate  107  swells toward the side of the sleeve  103 , as shown in FIG. 4, due to the pressure of the gas stored in the bottle  101 .  
           [0004]    The sleeve  103  is welded to the bottle  101  at the orifice  1   05 . A plurality of gas-outlets  109  are provided to allow the high-pressure gas to eject from the bottle  101  when the inflator  100  operates. The gas-outlets  109  are formed in the sidewall of the sleeve  103 . A perforation structure  111  is coupled with the sleeve  103  at an end thereof (an open end to the left in FIG. 4). The perforation structure  111  includes an initiator  111   a , a piston  111   b , and a barrel  111   c.    
           [0005]    An airbag body (not shown) is mounted to receive gas from the gas-outlets  109 .  
           [0006]    When the automobile receives an impact, a sensor (not shown) operates to actuate an ignition plug which ignites the initiator  111   a , thereby generating a blast. The blast pushes the piston  111   b  toward the sealing plate  107 . The tip of the piston  111   b  breaks the sealing plate  107  at a central part. Then, the high-pressure gas sealed in the bottle  101  is ejected into the sleeve  103  and is ejected and supplied into the bag body through the gas-outlets  109 .  
           [0007]    Hybrid-type inflators are disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 9- 175315, 10-152012,  and 10-230814 (each publication is incorporated by reference herein in its entirety).  
           [0008]    The hybrid-type inflators must be each provided with a combustion chamber in which a solid or liquid gas-generating agent is burned and a container which contains a compressed gas to be mixed with the combustion gas generated in the combustion chamber. The connection between the combustion chamber and the container in each case disclosed in the above-mentioned publications is performed by welding.  
           [0009]    As described above, the connection between each chamber in the stored-gas type or the hybrid type is generally performed by welding. In the hybrid type, in particular, which is provided with a plurality of the sealed chambers, the number of welding processes is increased. In the welding processes, generally, there are many working steps, quality inspection is complex, and manufacturing time and costs are increased.  
         SUMMARY OF THE INVENTION  
         [0010]    Accordingly, one object of the present invention is to provide an inflator which can be easily manufactured in a simple manufacturing process so as not to be disassembled. According to an embodiment of the present invention an inflator is provided. Preferably, the inflator comprises a bottle having an orifice and to be charged with a high-pressure gas; a sealing plate which seals the bottle at the orifice;  
           [0011]    and a perforation structure for breaking the sealing plate. The bottle and/or a receiving member which receives the perforation structure include projection-groove mating parts at which the bottle and the receiving member are coupled with each other by rotating the bottle or the receiving member while being mated with each other.  
           [0012]    The bottle and/or receiving member also includes hollow parts (or guides) which guide the mating parts when the bottle and the receiving member are coupled with each other, and key grooves, the key grooves formed in the bottle associating with the key grooves formed in the receiving member when the bottle or the receiving member rotates. The inflator further comprises keys for preventing the bottle or the receiving member from rotation by being inserted into the key grooves.  
           [0013]    The bottle charged with a high-pressure gas and the receiving member receiving the perforation structure are connected to each other at the projection-groove mating parts and are fixed to each other by the keys so that the bottle or the receiving member does not rotate. Therefore, both components can be assembled with each other in a simple assembly process without using welding, and the manufacturing operation thereby becomes easy.  
           [0014]    According to another embodiment of the present invention, an inflator is provided. The inflator comprises a bottle charged with a high-pressure gas and including an orifice. The inflator also includes a sealing plate which seals the bottle at the orifice; and a perforation structure for breaking the sealing plate. A receiving member is provided for receiving the perforation structure. The orifice of the bottle is provided with projections formed on the peripheral surface of the orifice, extending in the peripheral direction, and key grooves formed in the peripheral surface of the orifice, extending in the axial direction. The receiving member is provided, in the inner surface at an end thereof, with guide grooves extending in the axial direction of the receiving member, for guiding the projections of the bottle when the receiving member is coupled with the bottle, grooves extending in the peripheral direction, for mating with the projections after the receiving member or the bottle rotates, and key grooves for associating with the key grooves, after the receiving member or the bottle rotates, which are formed in the peripheral surface of the orifice of the bottle. The inflator further comprises keys for preventing the bottle or the receiving member from rotation by being inserted into the key grooves of the bottle and the receiving member. The orifice of the bottle is coupled with the receiving member at the end thereof, and the bottle and the receiving member are connected to each other with the rotation of the bottle or the receiving member.  
           [0015]    In an inflator according to another embodiment of the present invention, the length of each key groove formed in the peripheral surface of the orifice of the bottle is preferably at least twice the length of each key. The length of each key groove formed in the inner surface of the receiving member is preferably substantially the same as the length of each key or greater. The keys are preferably completely inserted into the key grooves formed in the inner surface of the receiving member after the bottle and the receiving member are assembled with each other.  
           [0016]    When the length of the key grooves of the bottle is increased, mounting of the keys becomes easy. When the length of the key grooves of the receiving member is substantially the same as the length of the keys or greater, the keys once inserted into the key grooves of the receiving member cannot be removed, whereby both components cannot be disassembled from each other.  
           [0017]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    These and other features, aspects and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below.  
         [0019]    [0019]FIG. 1 is a perspective view of a part of an inflator according to an embodiment of the present invention.  
         [0020]    [0020]FIG. 2 is a longitudinal sectional view showing the entire structure of the inflator shown in FIG. 1.  
         [0021]    FIGS.  3 (A)- 3 (C) are illustrations showing a method for fixing an orifice member and a diffuser to each other.  
         [0022]    [0022]FIG. 4 is a schematic longitudinal-sectional view of a stored-gas-type inflator.  
     
    
     DETAILED DESCRIPTION  
       [0023]    The present invention will be further described below with reference to the drawings.  
         [0024]    The entire structure and the operation of the inflator are described below with reference to FIG. 2. The inflator  1  includes a bottle  3 , a sealing plate  5 , a diffuser (receiving member)  7 , an initiator  9 , a barrel  11 , and a piston  1   3 . The diffuser  7  receives a structure including the initiator  9 , the barrel  11  and the piston  13 . The structure is provided for perforating the sealing plate  5 .  
         [0025]    The bottle  3  is preferably made of steel or similar material and is formed as a cylinder with a bottom. The bottle  3  is preferably charged with an inactive gas at a high pressure. A ring-like orifice member  16  is connected to the bottle  3  at an end, as shown in FIG. 2. The orifice member  16  is shown in the left of FIG. 2 at the side of an open end of the bottle  3 . Two sets of projections are formed, each set including two projections  43  being parallel to each other and extending in the peripheral direction of the orifice member  16 . The two sets of the projections  43  are disposed in two positions opposing each other at the periphery of the orifice member  16 . The orifice member  16  is provided with a flange  17 , which extends inwardly, at the inner periphery of the orifice member  16  at the side of the bottle  3 . An aperture  17   a  is formed at a central part of the flange  17 . An orifice  15  of the orifice member  1   6  to the left of the flange  17  in the FIG. 2 is straight open.  
         [0026]    The sealing plate  5  is fixed to the flange  17  of the orifice member  16  from the inner side of the bottle  3  by welding or similar process. The sealing plate  5  is a planar circular plate made of steel or similar material, and has a thickness of, for example, 0.4 mm. When the bottle  3  is not charged with high-pressure gas, the sealing plate  5  is kept flat. However, when a high-pressure gas is sealed in the bottle  3 , the sealing plate  5  swells in a spherical shape with the pressure of the gas toward the outside of the bottle  3  at the aperture  17   a  of the flange  17 .  
         [0027]    The diffuser  7  is a cylindrical member made of steel or similar material, the ends of which are open. The inner surface of the diffuser  7  is provided with two sets of grooves extending in the peripheral direction at the right end of the diffuser. Each set of grooves includes two grooves  41  parallel to each other and being formed in two positions opposing each other. The diffuser  7  and the orifice member  16  are fixed to each other by coupling the right open end of the diffuser  7  with the orifice  15  of the orifice member  16  and rotating the diffuser  7  and the orifice member  16  relative to each other, thereby mating the grooves  41  with the projections  43  of the orifice member  16 . The fixing structure is described further below.  
         [0028]    The left end of the diffuser  7  serves as an outlet  19  for the high-pressure gas. The gas outlet  19  is connected to an airbag which is not shown. The diffuser  7  is provided with a through-hole  7   a  formed in the sidewall at an upper part of the diffuser  7 . A housing  21  is inserted into and affixed at the through-hole  7   a . A closure  35  is coupled with the housing  21  at the inside thereof. The closure  35  is mounted with an ignition plug  23  and the initiator  9 . The housing  21  is provided at a lower part thereof with a space  25  extending substantially to the center of the diffuser  7 . A through-hole  27  is formed in the sidewall of the housing  21  in the lower part thereof at the bottle side.  
         [0029]    The cylindrical barrel  11  is connected to the through-hole  27  formed in the lower part of the housing. An inner hole  11   a  of the barrel  11  communicates with the space  25  of the housing  21 . The barrel  11  extends toward the bottle  3  along the central axis thereof. The barrel  11  is provided at the left end thereof with a step  29  with which the piston  13  comes into contact at a larger diameter portion  13   b  thereof, which is described below. The inner hole  11   a  of the barrel  11  extends straight to the right from the step  29  and is open at the right end of the barrel  11 . The right end (an end at the bottle  3  side) of the barrel  11  is connected to the inner surface of the flange  17  of the orifice member  16  via a supporting plate  31 . The supporting plate  31  is formed in a frusto-conical shape and is provided with a plurality of through-holes  33 . The through-holes  33  serve as gas paths for the gas flowing from the bottle  3  to the diffuser  7  when the sealing plate  5  is broken. A left end  31  a of the supporting plate  31  is inserted into the inner hole  11   a  of the barrel  11  at the right end thereof, and is formed as a step in the inner hole  11   a.    
         [0030]    The piston  13  is preferably made of stainless steel or similar material and is slidingly disposed in the barrel  11 . The piston  13  includes a head  13   a  at the right end (the bottle-side end) and the larger diameter part  1   3 b at the left end (the housing-side end). The piston head  13   a  has an outer diameter smaller than the inner diameter of the barrel  11  and the end of the head  13   a  is two-forked. The larger diameter part  13   b  has an outer diameter substantially the same as the inner diameter of the barrel  11 . A ring groove  13   c  is formed in an intermediate portion of the larger diameter part  13   b . The left end of the larger diameter part  13   b  of the piston  13  is in contact with the step  29  disposed at the rear end of the barrel  11  in a normal state. The piston head  13   a  is positioned away from the sealing plate  5 .  
         [0031]    When an object impacts with the automobile (or a similar event triggering the initiation of the safety device occurs), the ignition plug  23  of the inflator  1  operates.  
         [0032]    The ignition plug  23  ignites the initiator  9 , whereby a blast is ejected from the initiator  9  into the space  25  disposed in the lower part of the housing  21 . The blast goes into the barrel  11  through the through-hole  27  formed in the lower part of the housing and pushes the piston  13  toward the bottle  3  along the central axis of the barrel  11 . Then, the tip of the piston  13  cuts into the sealing plate  5  and breaks the sealing plate  5  at a portion of the sealing plate  5  corresponding to the shape of the tip of the piston  13 . The piston  13  moves by being pushed until it anchors to the end  31   a  of the supporting plate  31  at the larger diameter part  13   b  of the piston  13 . The piston  13  moves in a stable manner in the barrel  11  along the central axis thereof because the larger diameter part  13   b  of the piston  13  has a predetermined length.  
         [0033]    When the sealing plate  5  is broken, the piston  13  is pushed to the left in the drawing (i.e., away from the bottle  3 ) by the pressure of the high-pressure gas stored in the bottle  3 . The piston , back to the position where the larger diameter part  13   b  of the piston  13  is anchored at the step  29  disposed inside the barrel  11 . The high-pressure gas which has been stored in the bottle  3  flows into a space between the flange  17  and the supporting plate  31  through a part  5   a  of the sealing plate  5  at which the sealing plate  5  has been broken, goes into the diffuser  7  through the through-holes  33  of the supporting plate  31 , and is discharged through the gas outlet  19 .  
         [0034]    The configuration of the orifice member  16  and the diffuser  7  is described below with reference to FIG. 1. The outer diameter of the orifice member  16  is substantially the same as the inner diameter of the diffuser  7 . The orifice member  16  mates with the diffuser  7 . The orifice member  16  and the diffuser  7  are connected to each other with the projections and the grooves mating with each other with the orifice member  16  and the diffuser  7  being rotated relative to each other, and are fixed to each other by separate keys  45 . The keys  45  are preferably made of steel or similar material and are each formed in a rectangular parallelepiped shape.  
         [0035]    Two sets of the two projections  43  extending in the peripheral direction are formed on the periphery of the orifice member  16 . The two sets of the projections  43  are formed symmetrical to each other at an angle of 180° with respect to the axis of the orifice member  16 . Each projection  43  has a given height and width. The height of the projection  43  gradually decreases toward the longitudinal ends thereof. The length of each projection  43  in the peripheral direction is approximately ¼ of the circumference of the outer surface of the orifice member  16 .  
         [0036]    In the peripheral surface of the orifice member  16 , key grooves  47  which extend in the axial direction from the open end of the orifice member  16  are formed. The key grooves  47  are disposed symmetrical to each other at an angle of 180° with respect to the axis of the orifice member  16  and at an angle of 90° apart from the projections  43  around the axis of the orifice member  16 . Each key groove  47  is open at one end thereof at the open end of the orifice member  16  and the bottom of the key groove  47  is inclined so as to gradually merge into the peripheral surface of the orifice member  16  at the other end of the key groove  47 . The length of each key groove  47  is at least approximately twice the length of the key  45 . The bottom of each key groove  47  is flat in a portion from the open end thereof having a length twice the length of the key  45 .  
         [0037]    A set of the two grooves  41  parallel to each other and extending in the peripheral direction are formed in the inner surface of the diffuser  7 . Another set of the two grooves  41  is disposed symmetrical to and at an angle of 180° apart from the set of the two grooves  41  with respect to and around the axis of the diffuser  7 . The depth of the grooves  41  is substantially the same as the height of the projections  43  formed on the orifice member  16 . The width of each groove  41  is substantially the same as that of the projection  43 . The length in the peripheral direction of each groove  41  is approximately ¼ of the inner periphery of the diffuser  7 . The distance in the axial direction between the grooves  41  is the same as that in the axial direction between the projections  43 . The grooves  41  mate with the projections  43  of the orifice member  16 .  
         [0038]    The diffuser  7  is provided with two guide grooves  49  formed in the inner surface of the diffuser  7  and extending in the axial direction from the open end of the diffuser  7 . The two guide grooves  49  are disposed symmetrical to each other with respect to the axis of the diffuser  7 . The two guide grooves  49  are disposed at an angle of 180° apart from each other and an angle of 90° apart from the grooves  41  around the axis of the diffuser  7 . The depth of the guide grooves  49  is the same as the height of the projections  43  of the orifice member  16 . The width of each guide groove  49  is the same as the length of each projection  43  (that is, approximately ¼ of the inner periphery of the diffuser  7 ). The grooves  41  are formed between the two guide grooves  49  such that the bottoms of the grooves  41  are gradually inclined downward from the sidewalls of the guide grooves  49 . The length of each guide groove  49  in the axial direction is substantially the same as the distance between the open end and the groove  41  disposed at the rear side.  
         [0039]    A key groove  51  is formed extending in the axial direction from the open end of the diffuser  7  in a widthwise intermediate part of the bottom of each guide groove  49 .  
         [0040]    The section of each key groove  51  is rectangular. The length of the key groove  51  is substantially the same as that of the key  45 .  
         [0041]    A method for fixing the orifice member  16  and the diffuser  7  to each other is described below with reference to FIG. 3.  
         [0042]    As shown in FIG. 3(A), the keys  45  are firstly placed at the rearmost sides of the key grooves  47  of the orifice member  16 . The projections  43  of the orifice member  16  are aligned with the guide grooves  49  formed in the inner surface of the diffuser  7 , and the orifice member  16  and the diffuser  7  are coupled with each other. The orifice member  16  is inserted until the leading ends of the projections  43  reach the end walls of the guide grooves  49 .  
         [0043]    Then, the orifice member  16  and the diffuser  7  are rotated relative to each other by approximately 90° , as shown in FIG. 3(B). As a result, the two sets of the projections  43  of the orifice member  16  mate with the two sets of the grooves  41  of the diffuser  7 . In this case, both components mate with each other with the gradually inclined upper faces of the projections  43  smoothly coupling with the grooves  41 .  
         [0044]    With this coupling, the orifice member  16  and the diffuser  7  are prevented from being removed from each other in the axial direction.  
         [0045]    In this position, the key grooves  47  of the orifice member  16  associate with the key grooves  51  of the diffuser  7 , as shown in FIG. 3(B). The keys  45  are knocked deeply into the key grooves  51  from the rear sides at the bottle sides of the key grooves  47  toward the left in the drawing by using a tool. Since each key groove  51  of the diffuser  7  has a length the same as that of the key  45  or greater, the keys  45  are pressed completely into the diffuser  7  (see FIG. 3(C)). The orifice member  16  or the diffuser  7  cannot rotate due to the keys  45 . The keys  45  which have been once knocked deeply into the grooves  51  cannot be removed by ordinary means, whereby the orifice member  16  and the diffuser  7  are fixed to each other so as not to be removed from each other.  
         [0046]    As described above, according to the present invention, a bottle charged with a high-pressure gas and a container for a perforation structure are connected to each other so as not to be removed from each other by using projection-groove coupling and keys and key grooves. Therefore, the bottle and the container can be assembled with each other so as not to be removed from each other without performing welding, whereby an inflator easy to manufacture can be provided.  
         [0047]    The priority application, Japanese Patent Application No.2001-1 71 276, is hereby incorporated by reference herein in its entirety.  
         [0048]    Given the disclosure of the present invention, one versed in the art would appreciate that there may be other embodiments and modifications within the scope and spirit of the invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is to be defined as set forth in the following claims.