Patent Publication Number: US-2010127486-A1

Title: Inflator

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an inflator which is configured to discharge a compressed gas sealed in a compressed gas chamber from discharge ports by rupturing a rupture plate by a combustion gas spouted from a gas generator when the inflator is activated and relates to, for example, an inflator which can preferably be used in an airbag system which is installed on a vehicle for inflating an airbag to protect an occupant inside or a pedestrian outside of the vehicle. 
     2. Related Art 
     Conventionally, an inflator of this type includes a compressed gas chamber defined by closing an exit portion from which a compressed gas sealed therein is allowed to exit with a rupture plate and a housing installed so as to be consecutive to the exit port of the compressed gas chamber for holding a gas generator (a micro gas generator) which can rupture the rupture plate by a combustion gas spouted therefrom when the gas generator is activated. In addition, the housing has discharge ports formed between the gas generator and the exit port for discharging the compressed gas which flows out as a result of the rupture of the rupture plate to the outside thereof (for example, refer to JP-A-2006-502030). 
     In the inflator of this type, although an output of the generator is made small, for the rupture plate to be ruptured smoothly when the inflator is activated, a guide is provided at a gas exit port of the gas generator so as to cause an inflation gas spouted to converge on the rupture plate. This guide is formed so that an inner circumference thereof is narrowed in a tapered fashion towards a distal end thereof so that a combustion gas spouted from the gas generator is allowed to exit from a distal end with the flow velocity thereof increased so as to be concentrated on a small area on the rupture plate for a smooth rupture of the rupture plate. 
     In the inflator including the conventional guide for causing the combustion gas to converge, however, the guide is assembled closely on to an outer circumferential surface of the gas generator while extending from the gas generator towards the exit port, and further, the guide is inserted together with the gas generator into the housing from an opening on a side of the housing which faces the exit port. In addition, in order to restrict the movement of the guide towards the exit port of the housing, the guide is fixed to the housing by a distal end of the housing which lies on the exit port thereof being crimped to be bent into annular groove on the guide. 
     Namely, the assemblage of the conventional guide involves too many labor hours because a distal end of the housing is bent while being plastically deformed so that the guide is locked at an end face portion of the housing which faces the exit port so as to restrict the movement of the guide towards the exit port so that the guide is not dislocated from the gas generator towards the exit port by the combustion gas spouted from the gas generator. For example, when a compressed gas is sealed in the compressed gas chamber by increasing a pressure imposed thereon, the strength of the rupture plate needs to be increased, and as this occurs, as to the converging form in which the combustion gas converges on the rupture plate, a converging form needs to be adopted in which the combustion gas is caused to converge on a narrower area so as to rupture the rupture plate whose strength is so increased. However, as this occurs, a construction is then required in which the guide is locked on the housing with a stronger force so that the guide is not dislocated from the gas generator, and with the conventional inflators, there is still room for improvement in the holding construction of the guide by the housing. 
     SUMMARY OF THE INVENTION 
     The invention has been made with a view to solving the problem, and an object thereof is to provide an inflator in which a guide can be held to a housing strongly and stably even when the guide is assembled to the housing by simple assembling work. 
     According to an aspect of the invention, there is provided an inflator comprising: 
     a compressed gas chamber defined by closing an exit port through which a compressed gas sealed therein is allowed to exit with a rupture plate; 
     a housing installed so as to be consecutive to the compressed gas chamber which holds a gas generator which can rupture the rupture plate by a combustion gas spouted therefrom when the gas generator is activated and which has discharge ports formed between the gas generator and the exit port for discharging the compressed gas which flows out as a result of the rupture of the rupture plate to the outside thereof; and 
     a guide for converging the combustion gas spouted from the gas generator so as for the combustion gas to be guided to the rupture plate for promoting the rupture thereof, wherein 
     the guide comprises: 
     a spouting tube portion having a substantially cylindrical shape which extends to face the exit port at a distal end and of which an inside diameter dimension is made smaller than an opening dimension of the exit port; 
     a mounting seat which is disposed at a proximal portion of the spouting tube portion and which extends in a direction which intersects an axis of the spouting tube portion at right angles in a flange-like shape; and 
     a connecting portion having a bent plate shape which bends from the mounting seat to an inner circumferential side of the spouting tube portion into a substantially arc-like shape and disposed at a boundary portion between the mounting seat and the spouting tube portion, wherein 
     the housing comprises: 
     a holding tube portion for holding the gas generator on an inner circumferential side thereof; and 
     a connecting tube portion disposed to extend from the holding tube portion to the exit port, having a riser surface which extends from an inner circumferential surface of the holding tube portion towards an axis of the holding tube portion, extending towards the exit port with an inside diameter dimension made smaller than that of the holding tube portion and lying consecutive to the compressed gas chamber with the discharge ports provided so as to penetrate from an inner circumference to an outer circumference thereof, and wherein 
     the guide is installed with the spouting tube portion extending towards the exit portion while defining a space between an inner circumferential surface of the connecting tube portion and itself and the mounting seat brought into abutment with the riser surface so as to be held on the holding tube. 
     In the inflator according to the aspect of the invention, when the gas generator is activated to spout the combustion gas, the combustion gas strikes the rupture plate by way of the spouting tube portion of the guide. When this occurs, since the spouting tube portion of the guide extends towards the exit port at the distal end thereof and the inside diameter dimension of the spouting tube portion is made smaller than that of the exit port, the combustion gas can be concentrated to a smaller area on the rupture plate with the flow velocity thereof increased when the combustion gas exits from the distal end of the spouting tube portion whose opening is narrowed, so as to rupture the rupture plate smoothly. Then, when the rupture plate is ruptured, the exit port of the compressed gas chamber is opened, and the compressed gas flows towards the discharge ports in the connecting tube portion by passing between the spouting tube portion of the guide and the connecting tube portion of the housing so as to be discharged from the discharge ports. 
     The mounting seat of the guide is brought into abutment with the riser surface of the housing which is disposed so as to be opposed to the direction in which the combustion gas is spouted from the gas generator. Because of this, even in the event that the combustion gas is spouted from the gas generator to thereby impose a pressure at which the combustion gas is so spouted from the mounting seat to the inner circumferential surface of the connecting tube portion and further to the inner circumferential surface of the spouting tube portion, the riser surface of the housing can receive the mounting seat which attempts to move in the spouting direction of combustion gas in a squared fashion, whereby the guide can be kept held strongly to the housing. The guide only has to simply be held to the holding tube portion with the mounting seat in abutment with the riser surface of the housing, and the guide can easily be assembled to the housing by being welded to or press fitted in the portion of the housing where the riser surface is provided. In other words, the riser surface of the housing only receives the compression load when receiving the pressure at which the combustion gas is spouted via the mounting seat, and compared with the conventional inflators in which for the assemblage of the guide, the guide is locked on the housing by crimping the housing to bend it through plastic deformation, a sufficient thickness dimension in the spouting direction of combustion gas can easily be secured in advance without bending the housing when the guide is assembled thereto. As a result, the housing is allowed to hold the guide strongly and rigidly in an easy fashion by the simple construction of the riser surface and the simple assembling work. 
     Further, since the guide is not assembled to the gas generator but is assembled to the housing, in the event that a change is required in the converging form of combustion gas on the rupture plate by changing the length and/or inside diameter of the spouting tube portion, the shape of the mounting seat where the guide is assembled to the housing or the portion of the housing where the guide is assembled does not have to be changed, and hence, the change can easily be dealt with while the simple assembling work to the housing is maintained. 
     Consequently, in the inflator according to the aspect of the invention, even with the simple assembling work, the guide can be held to the housing stably, and further, even in the event that the change is required in the converging form of combustion gas on the rupture plate, the change can easily be dealt with. 
     In the inflator according to the aspect of the invention, in the event that the guide is configured to be held in the housing by the mounting seat being press fitted in a portion of the holding tube portion in the housing where the riser surface is situated, the assembling work of the guide to the housing is facilitated, reducing the manhours and costs involved in fabrication of the inflator. 
     Further, in the inflator according to the aspect of the invention, in the event that the gas generator is provided with a plurality of door portions on a surface thereof which faces the exit port which open at rupture portions formed to be ruptured radially from a center thereof when the combustion gas is spouted when the inflator is activated, it is desirable that the guide is held in the housing and is disposed in a position where the guide can receive the respective doors which open when the gas generator spouts the combustion gas by an inner circumferential surface of the connecting portion. 
     In this configuration, when the individual door portions of the gas generator open when the inflator is activated, the inner circumferential surface of the connecting portion of the guide receives the individual doors. The connecting portion has the bent plate shape which is bent into the substantially arc shape from the mounting seat to the inner circumference of the spouting tube portion, and the individual door portions which are received by the connecting portion open into the bent plate shape at an opening angle of about less than 90°. This suppresses the centrifugal force that would otherwise be imposed on the door portions, whereby a stress concentration in the vicinity of hinge portions which constitute centers of the opening of the individual door portions is made difficult to take place, thereby making it possible to prevent the separation of the door portions from the vicinity of the hinge portions in a proper fashion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic sectional view of an inflator which is an embodiment of the invention. 
         FIG. 2  is a partial enlarged sectional view showing the vicinity of a guide in the inflator shown in  FIG. 1 . 
         FIG. 3  is a partial enlarged sectional view showing the vicinity of the guide when the inflator shown in  FIG. 1  is activated. 
         FIG. 4  is a partial enlarged perspective view showing the vicinity of a distal end wall portion of a cup portion in a gas generator of the inflator shown in  FIG. 1 . 
         FIGS. 5A and 5B  are perspective views of the guide used in the inflator shown in  FIG. 1 , showing states in which the guide is shown from a front side and a rear side thereof. 
         FIG. 6  is a partial enlarged sectional view in the vicinity of a guide which results when the guide of the inflator shown in  FIG. 1  is changed. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, an embodiment of the invention will be described based on the drawings. An inflator  1  according to the embodiment shown in  FIG. 1  is used for discharging an inflation gas for inflating an airbag of an airbag system installed on a vehicle and for this inflator, an inflator of a hybrid type is adopted in which an inflation gas IG which is a mixture of a compressed gas CG and a combustion gas GG is discharged from discharge ports  18 . 
     As is shown in  FIG. 1 , the inflator  1  of this embodiment includes a compressed gas chamber  3  in which the compression gas CG is sealed, a housing  10  which holds a gas generator  22  and a guide  40 . The compressed gas chamber  3  is made up of a substantially cylindrical steel bottle  4 , and an opening  4   a  at a proximal portion of the bottle  4 , which lies away from a closed distal end portion of the bottle  4 , is closed by a closing wall  6 . An exit port  7  is provided in the closing wall  6 , and the exit port  7  is closed by a rupture plate  8  made up of a steel plate or the like. The compression gas CG is made up of a nitrogen gas, a helium gas, an argon gas or a mixture thereof, and the compression gas CG is filled in the compressed gas chamber  3  from a filling port  4   b.  The filling port  4   b  is closed by a sealing cap  5  which is welded to the bottle  4  after the compressed gas CG has been filled. In the case of this embodiment, the closing wall  6  is made by a diametrically contracted portion  19  at a distal end of the housing  10  being welded to an inner circumferential side of the opening  4   a,  and the rupture plate  8  is secured to the diametrically contracted portion  19  from an inner circumferential side of the compressed gas chamber  3  so as to close the exit port  7  described above at a distal end face side  20  of the diametrically contracted portion  19  where the exit port  7  is opened. 
     The gas generator  22  includes a cup portion  23  in an interior of which gas generants  30  are filled, an ignition squib  32  for burning the generants  30  to produce a combustion gas GG; and a holder  36  for connecting the cup portion  23  and the squib portion  32  together. In the squib  32 , an ignition portion  33  is installed at a distal end thereof which constitutes a side facing the cub portion  23  and a terminal portion  34  is installed at a proximal portion thereof facing the housing  10 , and a lead wire, not shown, is connected to the terminal portion  34  for inputting an electrical signal for igniting the ignition portion  33 . 
     As is shown in  FIGS. 2 and 4 , the cup portion  23  is made of a metal such as an aluminum alloy and includes a cylindrical circumferential wall portion  24  and a distal end wall portion  25  which is installed to close the circumferential wall portion  24  at a distal end of the circumferential wall portion  24  which faces the exit port  7 . As is shown in  FIG. 4 , thin rupture occurring portions  26 , where ruptures are expected to occur when the gas generator  22  is activated (when the gas generants  30  are burnt), are formed to extend linearly in a substantially radial direction from a center of the distal end wall portion  25 . In the case of this embodiment, the rupture occurring portions  26  are made by providing continuous cuts of a depth of the order of one half of the thickness of the distal end wall portion  25  on an external surface of the distal end wall portion  25 , and the rupture occurring portions  26  are formed at a plurality of portions (six portions in the case of this embodiment) on the distal end wall portion  25  so as to extend in the radial direction from the center of the distal end wall portion  25 . To describe this in greater detail, the rupture occurring portions  26  are not formed so as to divide the distal end wall portion  25  but are formed so that end portions of the rupture occurring portions  26  lie slightly further inwards than an outer circumferential edge of the distal end wall portion  25 . Portions of the distal end wall portions  25  which are situated between the rupture occurring portions  26  are defined as door portions  27 , and these six door portions  27 , each having a substantially triangular plate shape, are allowed to open radially from portions in the vicinity of a boundary portion with the circumferential wall portion  24  (in the vicinity of an outer circumferential edge of the distal end wall portion  25 ) as hinge portions  28  which constitute centers of the opening of the door portions  27  when the rupture occurring portions  26  are ruptured as a result of the activation of the gas generator  22 . 
     The gas generants  30  are made by forming a predetermined chemical, which can produce a combustion gas GG when they are burnt, into a predetermined shape, and in the case of the embodiment, the gas generants  30  are formed into a substantially spherical shape and are filled in the cup portion  23  (refer to  FIGS. 1 and 2 ). 
     As is shown in  FIG. 1 , the holder  36  is made of a metal such as an aluminum alloy and has a substantially cylindrical shape. The holder  36  is crimped to be diametrically contracted at front and rear ends thereof with the cup portion  23  and the squib  32  inserted therein, so as to hold the cup portion  23  and the squib  32  so that they are joined together. 
     As is shown in  FIG. 1 , the housing  10  is made of a metal such as steel and has a substantially cylindrical shape. The housing  10  is installed to be consecutive to an opening  4   a  of the bottle  4  which lies at a proximal portion of the compressed gas chamber  3 . The housing  10  includes a holding tube portion  11  for holding the gas generator  22  on an inner circumferential side thereof and a connecting tube portion  15  which extends from the holding tube portion  11  towards the compressed gas chamber  3 . 
     The holding tube portion  11  includes a crimping portion  12  which is disposed at an end of a proximal portion  11   a  (refer to  FIG. 1 ) for crimping the holder portion  36  of the gas generator  22  so as to hold the gas generator  22  so as not to move back and forth and a cylindrical straight portion  13  which extends from the crimping portion  12  to a distal end portion  11   b  (refer to  FIG. 2 ) which lies to face the exit port  7  with an inside diameter dimension thereof remaining constant. 
     As is shown in  FIG. 2 , the connecting tube portion  15  includes a straight portion which lies consecutive to the straight portion  13  of the holding tube portion  11  and the diametrically contracted portion  19  which lies on a side thereof which faces the compressed gas chamber  3 . The straight portion  17  extends towards the exit port  7  and is formed into a cylindrical shape. An inside diameter dimension D 3  of the straight portion  17  is made smaller than an inside diameter dimension D 1  of the straight portion  13  of the holding tube portion  11  so as to have a riser surface  16  which extends from an inner circumferential surface  12   a  of the straight portion  13  of the holding portion towards an axis O of the holding portion  11 . The diametrically contracted portion  19  is formed to extend from a distal end of the straight portion  17  while being diametrically contracted so that an inside diameter dimension D 4  thereof is made narrower than the inside diameter dimension of the straight portion  17 , and the exit port  7  is formed in the diametrically contracted portion  19 . As has been described before, the rupture plate  8  is secured to the distal end face  20  of the diametrically contracted portion  19 . 
     The plurality of (four, in the case of this embodiment) discharge ports  18  are opened in the straight portion  17  of the connecting tube portion  15  radially along a circumferential direction so as to penetrate through the straight portion  17  from an inner to an outer circumference thereof. 
     The straight portion  13  of the holding tube portion  11  includes, as is shown in 
       FIG. 2 , a fitting portion  13   b  which are formed by slightly contracting the inner circumferential surface  13   a  in the diametrical direction at a portion lying in the vicinity of the rising surface  16 . An inside diameter dimension D 2  of this fitting portion  13   b  is set to such a dimension that enables the fitting of a mounting seat  41  of the guide  40  in the fitting portion  13   b,  and a length dimension L 1  of the fitting portion  13   b  is set to be substantially equal to a thickness dimension T 1  of the mounting seat  41  (refer to  FIG. 3 ). 
     A thickness dimension L 0  (refer to  FIG. 2 ) of the riser surface  16  of the holding tube portion  11 , which supports the mounting seat  41  of the guide  40 , is set so as to have a sufficient strength. In the case of this embodiment, the thickness dimension L 0  of the portion of the holding tube portion  11  where the riser surface  16  is formed is set so as to be referred to as a length from the riser surface  16  to the distal end surface  20  of the housing  10  and hence, a recess portion which recedes as deep as an area where the riser surface  16  is formed is not provided at all along the full circumference in the circumferential direction in an area extending from the riser surface  16  to the distal end surface  20 . 
     The guide  40  is made of a metal such as an ultra high strength steel and includes the mounting seat  41 , a connecting portion  42  and a spouting tube portion  43 , as is shown in  FIGS. 2 ,  5 A and  5 B. The spouting tube portion  43  has a cylindrical shape whose inside diameter dimension D 5  is made smaller than an opening dimension (the inside diameter dimension of the diametrically contracted portion  19 ) and extends towards the exit port  7  at a distal end  43   a  thereof. The mounting seat  41  is disposed at a proximal portion of the spouting tube portion  43  and has a substantially ring shape which extends in a flange-like shape in a direction which intersects an axis of the spouting tube portion  43  at right angles. The connecting portion  42  has a bent plate shape which is bent into a substantially arc shape (in the case of this embodiment, an arc of a quarter of a circle) from the mounting seat to an inner circumferential side of the spouting tube portion  43  and is disposed at a boundary portion between the mounting seat  41  and the spouting tube portion  43  so as to connect the mounting seat  41  to the spouting tube portion  43 . 
     In the case of this embodiment, a thickness dimension T 1  of the guide  40  is set so as to be equal at the respective constituent portions. Incidentally, in the case of this embodiment, the thickness dimension T 1  of the guide  40  is referred to as 1.6 mm, and a thickness T 0  of the bottle  4  is referred to as 2.0 mm. 
     Further, in this guide  40 , an outside diameter D 6  of the spouting tube portion  43  is made smaller than the inside diameter dimension D 3  of the straight portion  17  so that the spouting tube portion  43  can extend towards the exit port  7  with a space H defined between an inner circumferential surface  15   a  of the connecting tube portion  15  and the spouting tube portion  43 , and the guide  40  is installed so as to be held on to the housing  11  with the mounting seat  41  kept in abutment with the riser surface  16 . 
     In the case of the embodiment, as is shown in  FIG. 2 , an outside diameter dimension D 7  of the mounting seat  41  is set to be equal to the inside diameter dimension D 2  of the fitting portion  13   b  or slightly smaller than the inside diameter dimension D 2  so that the guide  40  is held to the housing  10  by the mounting seat  41  being fitted in the portion of the holding tube portion  11  of the housing  10  where the riser surface  16  is formed (the fitting portion  13   b ). Further, The outside diameter D 6  of the spouting tube portion  43  is set to be equal to the inside diameter dimension D 4  of the exit port  7 . 
     The guide  40  is disposed so as to be fixed (held) to the holding tube portion  11  in a position where the door portions  27  which are opened when the combustion gas GG is spouted from the gas generator  22  can be received by an inner circumferential surface  42   a  of the connecting portion  42  (refer to  FIG. 3 ). 
     In the inflator  1  of the embodiment, firstly, the guide  40  is inserted from the proximal portion  11   a  of the housing  10  into which the gas generator  22  has not yet been assembled with the spouting tube portion  43  making a leading end and is then press fitted in the fitting portion  13   b  of the holding tube portion  11  so that the mounting seat  41  is brought into abutment with the riser surface  16 . Following this, the gas generator  22 , in which the cup portion  23  which is filled with the gas generants  30  and the squib  32  are made integral with each other by the holder  36 , is inserted into the holding tube portion  11 , and the crimping portion  12  is crimped so as to hold the gas generator  22  on to the holding tube portion  11 . Thereafter, the rupture plate  8  is secured to the distal end surface  20  of the housing  10 , and then, the housing  10  is inserted into the opening  4   a  of the bottle  4  and is then welded to the bottle  4 . Thereafter, a compressed gas CG is filled in the interior of the compressed gas chamber  3  from the filling port  4   b,  and the filling port  4   a  is closed by the sealing cap  5 , whereby the inflator  1  can be fabricated. 
     In the inflator  1  of this embodiment, when the gas generator  22  is activated, the ignition portion  33  of the squib  32  is ignited, and the gas generants  30  are fired to produce a combustion gas GG The combustion gas GG so produced push opens the individual door portions  27  of the cup portion  23  so as to be spouted from the gas generator  22 . Then, the combustion gas GG so spouted strikes the rupture plate  8  by way of the spouting tube portion  43  of the guide  40 . As this occurs, since the spouting tube portion  43  of the guide  40  extends towards the exit hole  7  at the distal end thereof and the inside diameter dimension D 5  of the distal end  43   a  of the spouting tube portion  43  is made smaller than the opening dimension (the inside diameter dimension) D 4  of the exit port  7 , the combustion gas GG is spouted from the distal end  43   a  whose opening is narrowed with the increasing flow velocity so as to be concentrated to the small area on the rupture plate  8 , thereby making it possible to rupture the rupture plate  8  in a smooth fashion, as is shown in  FIG. 3 . When the rupture plate  8  is ruptured, the exit port  7  of the compressed gas chamber  3  is opened, and the compressed gas CG flows out of the exit port  7  so as to be mixed with the combustion gas GG for production of an inflation gas IG The inflation gas IG so produced then flows to a discharge port  18  of the connecting tube portion  15  by way of the space H defined between the spouting tube portion  43  of the guide  40  and the connecting tube portion  15  of the housing  10 , so as to be discharged from the discharge ports  18 . 
     In the inflator  1  of the embodiment, the guide  40  is installed in the housing  10  so that the mounting seat  41  is brought into abutment with the riser surface  16  of the housing  10  which is disposed so as to face the spouting direction SD of combustion gas GG from the gas generator  22 . By this configuration, even in the event that the pressure at which the combustion gas GG is spouted is imposed from the mounting seat  41  on the inner circumferential surface  42   a  of the connecting portion  42  and further on the inner circumferential surface  43   b  of the spouting tube portion  43 , the riser surface  16  of the housing  10  can receive the mounting seat  41  which attempts to move in the spouting direction SD of combustion gas GG in the squared fashion, whereby the guide  40  can be kept held to the housing  10  strongly and stably. The guide  40  only has to simply be held to the holding tube portion  11  with the mounting seat  41  kept in abutment with the riser surface  16  of the housing  10  and can easily be assembled to the housing  10  by being welded to or press fitted in the portion (the fitting portion)  13   b  of the housing  10  where the riser surface  16  is formed. In other words, when receiving the pressure at which the combustion gas GG is spouted via the mounting seat  41 , the riser surface  16  of the housing  10  only has to receive the compression load, and the sufficient thickness dimension L 0  in the spouting direction SD can easily be secured in advance without bending the housing  10  when the guide  40  is assembled, compared with the conventional inflator in which the housing is crimped to be bent for plastic deformation so as to lock the guide when the guide is assembled. As a result, the housing  10  is allowed to easily hold the guide  40  strongly by the simple construction of the riser surface  16  and the simple assembling work. 
     Since the guide  40  is not assembled to the gas generator  22  but is assembled to the housing  10 , even in the event that a change is required in the converging form of the combustion gas GG on the rupture plate  8  by changing the length dimension L 2  and/or the inside diameter D 5  of the spouting tube portion  43 , the shape of the mounting seat  41  which constitutes the portion where the guide  40  is assembled to the housing  10  or the assembling portion (the fitting portion  13   b ) on the housing  10  does not have to be changed, and the change can easily be dealt with while the simple assembling work to the housing  10  is maintained. 
     For example, in a guide  40 A shown in  FIG. 6 , in order to rupture a rupture plate  8 A whose strength is increased in conjunction with an increase in pressure of the compressed gas CG smoothly by the use of the gas generator  22  whose output remains unchanged, compared with the guide  40  shown in  FIG. 2 , the guide  40 A is changed so that a length dimension L 2  of a spouting tube portion  43  is lengthened and an inside diameter dimension D 5  is made smaller. Namely, in this guide  40 A, a converging form of combustion gas GG on the rupture plate  8  is configured so that the combustion gas GG is concentrated to a smaller area, and even in this case, the shape of the mounting seat  41  which constitutes the assembling portion of the guide  40 A to the housing  10  or the assembling portion (the fitting portion  13   b ) on the housing  10  does not have to be changed, the change can easily be dealt with while the simple assembling work is maintained in which the guide  40 A is press fitted in the fitting portion  13   b  for assemblage to the housing  10 . 
     Consequently, in the inflator  1  of the embodiment, even though the simple assembling work is adopted, the guide  40 / 40 A can be held to the housing  11  stably, and further, even in the event that a change is required in the converging configuration of combustion gas GG on the rupture plate  8 / 8 A, the change can easily be dealt with. 
     In the inflator  1  of this embodiment, the guide  40 / 40 A is configured to be held on to the housing  10  by the mounting seat  41  being press fitted in the portion (the fitting portion)  13   b  of the holding tube portion  11  where the riser surface  16  is formed, whereby the assembling work of the guide  40 / 40 A to the housing  10  becomes easy, thereby making it possible to reduce the manhours and costs involved in the fabrication of the inflator  1 . 
     Further, in the inflator  1  of the embodiment, the gas generator  22  is configured to include the plurality of door portions  27  which are formed on the side facing the exit port  7  so as to open at the rupture portions which are ruptured radially from the center thereof when the combustion gas GG is spouted from the gas generator  22  when it is activated. In addition, the guide  40  is held in the housing  10  and is disposed in the position where the individual door portions  27  can be received by the inner circumferential surface  42   a  of the connecting portion  42  when the door portions  27  are opened by the combustion gas GG spouted from the gas generator  22 . Because of this, in the inflator  1  of the embodiment, when the individual door portions  27  of the gas generator  22  are opened when the gas generator  22  is activated, the inner circumferential surface  42   a  of the connecting portion  42  of the guide  40  is allowed to receive the door portions  27  so opened. The connecting portion  42  has the bent plate shape which bents into the substantially arc shape (in the case of the embodiment, the arc of a quarter of a circle) from the mounting seat  41  to the inner circumferential surface  43   b  of the spouting tube portion  43 , and the individual door portions  27  which are received by the connecting portion  42  open into the bent plate shape at an opening angle of about less than 90°. This suppresses the centrifugal force that would otherwise be imposed on the door portions, whereby a stress concentration in the vicinity of the hinge portions  28  which constitute the centers of the opening of the individual door portions  27  is made difficult to take place, thereby making it possible to prevent the separation of the door portions  27  from the vicinity of the hinge portions  28  in a proper fashion. 
     In the inflator  1  of the embodiment, while the guide  40 / 40 A is described as being held to the holding tube portion  11  of the housing  10  by being press fitted in the fitting portion  13   b,  the guide  40 / 40 A may be held (fixed) to the holding tube portion  11  with the mounting seat  41  kept in abutment with the riser surface  16  by making use of welding such as resistance welding. Of course, the guide may be held to the holding tube portion by making use of press fitting and welding in parallel. 
     In addition, in the embodiment, while the hybrid type inflator in which the compressed gas and the combustion gas are mixed together to be discharged from the inflator is illustrated as being applied to the inflator, the invention may be applied to an inflator of a stored type in which a combustion gas spouted from a gas generator is used simply for rupturing a rupture plate. 
     Further, there exists a case in which the rupture plate is ruptured by a shock wave generated when the gas generator is activated, and even in that case, since the shock wave can be caused to converge to be spouted from the distal end of the spouting tube portion, the invention can be applied to the inflator in which the rupture of the rupture plate is mainly implemented by the shock wave produced when the gas generator is activated.