Patent Publication Number: US-2018043854-A1

Title: Gas generator

Description:
TECHNICAL FIELD 
     The present invention relates to a gas generator which is usable for an airbag apparatus of a vehicle or the like. 
     DESCRIPTION OF RELATED ART 
     When a gas generating agent is loaded as a gas generating source of a gas generator, mist is generated by combustion of the gas generating agent. The mist is mainly molten metal components contained in the gas generating agent, and it is desirable that the mist is prevented, as much as possible, from being discharged to an outside of the gas generator. 
     U.S. Pat. No. 5,584,506 discloses an inflator 10 in which a plurality of cylindrical members are stacked in a radial direction to form a filter (FIGS. 2 and 3). 
     A combustion gas generated by combustion of gas generating disks 114 enters a first portion 250 of a filter chamber 140 from openings 68, and then enters a second portion 252 from inner openings 220. Thereafter, the combustion gas flows from outer openings 182 into a third portion 254, and then is discharged from gas outlet openings 58. 
     When the combustion gas enters the second portion 252 from the inner openings 220, the combustion gas collides with and bypasses an inner tab 200 and then enters the second portion 252. When the combustion gas enters the third portion 254 from the outer openings 182, the combustion gas collides with and bypasses an outer tab 180 and then enters the third portion 254. As a result of such repeated collision and bypassing, mist is easily captured. 
     The inner tab 200 and the outer tab 180 are kept inclined as shown in FIGS. 2 and 3 even before actuation, and they are not the ones which change to the state shown in FIGS. 2 and 3 at the time of actuation. 
     U.S. Pat. No. 6,142,515 discloses a gas generator having two combustion chambers. The inner combustion chamber is closed by a cap 260, and when the internal pressure rises at the time of actuation, the cap 260 is disengaged and the gas is discharged to an outside of the combustion chamber. Before actuation, the combustion chamber is closed by the cap 260, but once the combustion chamber is opened, the cap 260 is completely separated from the wall surface forming the combustion chamber, and the cap 260 may block a gas discharge path. 
     SUMMARY OF INVENTION 
     The first aspect of the present invention (hereinafter, referred to as “the first aspect”) provides a gas generator including, in a cylindrical housing, a gas generation chamber accommodating a gas generating agent as a gas generating source and an ignition device, 
     the ignition device being disposed at a first end surface of the cylindrical housing, and a second end surface, which is axially opposite to the first end surface of the cylindrical housing, being closed by a closing member, 
     the closing member having a first surface on the side of the gas generation chamber and a second surface on the back side of the first surface, 
     the closing member having a fragile portion formed such that a part thereof is ruptured when the first surface receives a pressure of a gas including a combustion gas, and the ruptured portion is bent and opened to an axially opposite side of the first surface, 
     a gas discharge port for the combustion gas being formed by the ruptured portion which is bent and opened from a surface of a non-ruptured portion after the part of the closing member is ruptured along the fragile portion, 
     a control device restricting an angle between the second surface of the closing member and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being,
         a member which is adjusted to have such a distance that the bent ruptured portion of the closing member is in contact therewith, or   a support portion which is formed to protrude from the second surface of the closing member at a position such as to be in contact with the bent ruptured portion.       

     The second aspect of the present invention (hereinafter, referred to as “the second aspect”) provides a gas generator including, in a cylindrical housing, a gas generation chamber accommodating a gas generating agent as a gas generating source, and a diffuser portion provided with a gas discharge port, 
     a closing member closing between the gas generation chamber and the diffuser portion, 
     the closing member having a first surface on the side of the gas generation chamber and a second surface on the back side of the first surface, 
     the closing member having a fragile portion formed such that a part thereof is ruptured when the first surface receives a gas pressure from the gas generating source, and the ruptured portion is bent and opened toward the diffuser portion, 
     a gas discharge path leading to a gas discharge port being opened by the ruptured portion which is bent and opened from a surface of a non-ruptured portion after the part of the closing member is ruptured along the fragile portion, 
     a control device restricting an angle between the second surface of the closing member and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being,
         a wall surface of the diffuser portion which is adjusted to have such a distance that the bent ruptured portion of the closing member is in contact therewith, or   a support portion which is formed to protrude from the second surface of the closing member at a position such as to be in contact with the bent ruptured portion.       

     The third aspect of the present invention (hereinafter, referred to as “the third aspect”) provides a gas generator including, in a cylindrical housing, a gas generation chamber and a diffuser portion provided with a gas discharge port, 
     the gas generation chamber being a combination of a combustion chamber accommodating a gas generating agent and an ignition device, and a pressurized gas chamber filled with a gas, 
     the combustion chamber being arranged on the side of a first end surface of the cylindrical housing, the diffuser portion which is provided with the gas discharge port being arranged on the side of a second end surface which is axially opposite to the first end surface of the cylindrical housing, and the pressurized gas chamber being arranged between the combustion chamber and the diffuser portion, 
     a first closing member closing between the combustion chamber and the pressurized gas chamber, and a second closing member closing between the pressurized gas chamber and the diffuser portion, 
     the first closing member having a first surface on the side of the combustion chamber and a second surface on the back side of the first surface, which is on the side of the pressurized gas chamber, 
     the second closing member having a first surface on the side of the pressurized gas chamber and a second surface on the back side of the first surface, which is on the side of the diffuser portion, 
     the first closing member having a fragile portion formed such that a part thereof is ruptured when the first surface receives a combustion gas pressure generated in the combustion chamber, and the ruptured portion is bent and opened toward the pressurized gas chamber, 
     after the part of the first closing member is ruptured along the fragile portion, the ruptured portion being bent from a non-ruptured portion and opened so that a gas discharge path from the combustion chamber to the pressurized gas chamber is opened, 
     a control device restricting an angle between the second surface of the first closing member and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being a support portion which is formed to protrude from the second surface of the first closing member at a position such as to be in contact with the bent ruptured portion, 
     the second closing member having a fragile portion formed such that a part thereof is ruptured when the first surface receives a gas pressure of a combustion gas generated in the combustion chamber and a pressurized gas, and the ruptured portion is bent and opened toward the diffuser portion, 
     after the part of the second closing member is ruptured along the fragile portion, the ruptured portion being bent from a non-ruptured portion and opened so that a gas discharge path from the pressurized gas chamber to the diffuser portion is opened, 
     a control device restricting an angle between the second surface of the second closing member and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being,
         a wall surface of the diffuser portion which is adjusted to have such a distance that the bent ruptured portion of the second closing member is in contact therewith, or   a support portion which is formed to protrude from the second surface of the second closing member at a position such as to be in contact with the bent ruptured portion.       

     The forth aspect of the present invention (hereinafter, referred to as “the forth aspect”) provides a gas generator including, in a cylindrical housing, a gas generation chamber and a diffuser portion provided with a gas discharge port, 
     the gas generation chamber being a combination of a combustion chamber accommodating a gas generating agent and an ignition device, and a pressurized gas chamber filled with a gas, 
     the combustion chamber being arranged on the side of a first end surface of the cylindrical housing, the pressurized gas chamber being arranged on the side of a second end surface which is axially opposite to the first end surface of the cylindrical housing, and the diffuser portion being arranged between the combustion chamber and the pressurized gas chamber, 
     a first closing member closing between the combustion chamber and the diffuser portion, and a second closing member closing between the diffuser portion and the pressurized gas chamber, 
     the first closing member having a first surface on the side of the combustion chamber and a second surface on the back side of the first surface, which is on the side of the diffuser portion, 
     the first closing member having a fragile portion formed such that a part thereof is ruptured when the first surface receives a combustion gas pressure generated in the combustion chamber, and the ruptured portion is bent and opened toward the diffuser portion, 
     after the part of the first closing member is ruptured along the fragile portion, the ruptured portion being bent from a non-ruptured portion and opened so that a gas discharge path from the combustion chamber to the diffuser portion is opened, 
     a control device restricting an angle between the second surface of the first closing member and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being,
         a member which is adjusted to have such a distance that the ruptured portion of the first closing member is in contact therewith, or   a support portion which is formed to protrude from the second surface of the first closing member at a position such as to be in contact with the bent portion.       

    
    
     
       BRIEF DESCRIPTION OF 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 no limitative of the present invention and wherein: 
         FIG. 1  shows, in (a), a cross-sectional view in the axial direction of a gas generator according to the present invention. However, a control device is not shown.  FIG. 1  shows, in (b), a plan view from the side of the second surface of the closing member used in (a) in  FIG. 1 ; 
         FIG. 2  shows, in (a), a cross-sectional view illustrating a state after actuation of the gas generator shown in  FIG. 1  and, in (b), a perspective view of (a) in  FIG. 2 ; 
         FIG. 3  shows a cross-sectional view for explaining an operation of the closing member used in (a) in  FIG. 1 ; 
         FIG. 4  shows, in (a), a cross-sectional view illustrating a control device in the gas generator shown in  FIG. 1  and, in (b), a perspective view of (a) in  FIG. 4 ; 
         FIG. 5  shows, in (a), a cross-sectional view illustrating a control device of another embodiment in the gas generator shown in  FIG. 1  and, in (b), a cross-sectional view illustrating a state after actuation of (a) in  FIG. 5 ; 
         FIG. 6  shows a cross-sectional view in the axial direction of a gas generator of another embodiment; 
         FIG. 7  shows, in (a), a plan view of the closing member taken from the side of the diffuser portion. A gas discharge port is shown by a broken line to clarify the positional relationship with the gas discharge port.  FIG. 7  shows, in (b), a partial cross-sectional view in the axial direction of the gas generator including the closing member shown in (a) in  FIG. 7 ; 
         FIG. 8  shows, in (a), a plan view of a closing member and, in (b) a plan view of a closing member of another embodiment which differs from that shown in (a) in  FIG. 8 . In (a) and (b) in  FIG. 8 , gas discharge ports are shown by broken lines to clarify the positional relationship with the gas discharge ports.  FIG. 8  shows, in (c), a partial cross-sectional view in the axial direction of the gas generator including the closing member shown in (a) or (b) in  FIG. 8 ; 
         FIG. 9  shows, in (a) , a plan view of a closing member and, in (b), a plan view of a closing member of an embodiment which differs from that shown in (a) in  FIG. 9 . In (a) and (b) in  FIG. 9 , gas discharge ports are shown by broken lines to clarify the positional relationship with the gas discharge ports.  FIG. 9  shows, in (c), a partial cross-sectional view in the axial direction of the gas generator including the closing member shown in (a) or (b) in  FIG. 9 ; 
         FIG. 10  shows, in (a), a plan view of a closing member. A gas discharge port is shown by a broken line to clarify the positional relationship with the gas discharge port.  FIG. 10  shows, in (b), a partial cross-sectional view in the axial direction of the gas generator including the closing member shown in (a) in  FIG. 10 ; 
         FIG. 11  shows a cross-sectional view in the axial direction of a gas generator of yet another embodiment; 
         FIG. 12  shows a cross-sectional view in the axial direction of a gas generator of yet another embodiment; 
         FIG. 13  shows a cross-sectional view in the axial direction illustrating a preferred embodiment of the gas generator shown in  FIG. 12 ; 
         FIG. 14  shows a partially enlarged view (before actuation) of  FIG. 13 ; 
         FIG. 15  shows a partially enlarged view (during actuation) of  FIG. 13 ; and 
         FIG. 16  shows a partially enlarged view (after completion of actuation) of  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The present invention is to provide a gas generator capable of reducing a discharge amount of mist, which is generated during combustion, from the gas discharge port. 
     In the gas generator according to the first aspect, the second end surface of the cylindrical housing is closed by a closing member, and a fragile portion in a desired shape is formed in the closing member. 
     When a gas pressure is received on the first surface of the closing member at the time of actuation of the gas generator, the closing member is ruptured along the fragile portion, and then the ruptured portion is bent from a surface of a non-ruptured portion to the opposite side of the first surface. 
     A configuration of the fragile portion is not particularly limited, but the fragile portion is formed such that a non-ruptured portion remains even when the fragile portion is ruptured, and the ruptured portion does not fall off from the closing member and is bent from a surface of the non-ruptured portion. 
     For example, when the fragile portion formed in the closing member is composed of three sides of a quadrangle, the three sides are ruptured at the time of actuation, but the remaining one side of the quadrangle remains non-ruptured, and the ruptured portion formed of the three sides are bent from the non-ruptured side, thereby opening the closing member. 
     Here, to facilitate rupturing, the fragile portion may have a U-shape as a whole in which two corners formed by the three sides of a quadrangle are rounded. 
     The quadrangle may be a square, a rectangle, a trapezoid, an irregular shape, or the like. 
     For example, when the fragile portion formed in the closing member is composed of two sides of a triangle, two sides are ruptured at the time of actuation, but the remaining one side of the triangle remains non-ruptured, and the ruptured portion formed of the two sides are bent from the non-ruptured side, thereby opening the closing member. 
     Here, to facilitate rupturing, one corner between the two sides of the triangle may be rounded. 
     For example, when the fragile portion formed in the closing member is composed of a part of the circumference of a circle (for example, a length portion of 60% to 80% of the circumference), the length portion of 60% to 80% of the circumference is ruptured, but the length portion of 20% to 40% of the circumference remains non-ruptured, and the ruptured portion (the length portion of 60% to 80% of the circumference) is bent from a surface of the non-ruptured portion (the length portion of 20% to 40% of the circumference), thereby opening the closing member. 
     The circle may be an ellipse. 
     The gas generator of the first aspect has a control device for restricting an angle between the second surface of the closing member and the bent ruptured portion to be 5 degrees to 85 degrees when the ruptured portion of the closing member is bent and opened from the surface of the non-ruptured portion as described above. 
     Thus, when the ruptured portion is bent and opened from the surface of the non-ruptured portion, the ruptured portion is bent in a state of being inclined with respect to the second surface of the closing member (a state of being inclined at the abovementioned 5 degrees to 85 degrees). As a result, the combustion gas discharged from the opening collides with and bypasses the ruptured portion in the inclined state before being discharged, so that mist is easily captured thereby. 
     The control device is:
     (I) a member which is adjusted to have such a distance that a part of the bent ruptured portion of the closing member is in contact therewith; or   (II) a support portion which is formed on the second surface of the closing member at a position such as to be in contact with a part of the bent ruptured portion.   

     The member of the control device (I) can be a plate-like member fixed at a position such as to cover the fragile portion to be ruptured at a distance therefrom on the side of the second end surface of the cylindrical housing. 
     The distance is set such that the angle of 5 degrees to 85 degrees between the ruptured portion and the second surface of the closing member is obtained when a part of the ruptured portion bent from the surface of the non-ruptured portion of the fragile portion comes into contact with the plate-like member and the bending stops. 
     The support portion serving as the control device (II) is a convex portion formed so as to protrude from the second surface of the closing member. A formation position and a shape of the convex portion and a height thereof from the second surface are set to have the angle of 5 degrees to 85 degrees between the ruptured portion and the second surface of the closing member when bending of the ruptured portion of the fragile portion bent from the surface of the non-ruptured portion stops. 
     In the second aspect, a cylindrical housing has therein a gas generation chamber accommodating a gas generating agent as a gas generating source, and a diffuser portion provided with a gas discharge port. 
     A gas generating agent is loaded in the gas generation chamber as a gas generating source, but both a gas generating agent and a pressurized gas may be loaded as a gas generating source. 
     A closing member closes between the gas generation chamber and the diffuser portion. A fragile portion in a desired shape is formed in the closing member. 
     When a gas pressure is received on a first surface of the closing member at the time of actuation of the gas generator, the closing member is ruptured along the fragile portion and then the ruptured portion is bent from a surface of the non-ruptured portion to the opposite side of the first surface. 
     A configuration of the fragile portion is not particularly limited, but the fragile portion is formed such that a non-ruptured portion remains even when the fragile portion is ruptured, and the ruptured portion does not fall off from the closing member and is bent from a surface of the non-ruptured portion. 
     For example, when the fragile portion formed in the closing member is composed of three sides of a quadrangle, the three sides are ruptured at the time of actuation, but the remaining one side of the quadrangle remains non-ruptured, and the ruptured portion formed of the three sides are bent from the non-ruptured side, thereby opening the closing member. 
     Here, to facilitate rupturing, the fragile portion may have a U-shape as a whole in which two corners formed by the three sides of a quadrangle are rounded. 
     The quadrangle may be a square, a rectangle, a trapezoid, an irregular shape, or the like. 
     For example, when the fragile portion formed in the closing member is composed of two sides of a triangle, two sides are ruptured at the time of actuation, but the remaining one side of the triangle remains non-ruptured, and the ruptured portion formed of the two sides are bent from the non-ruptured side, thereby opening the closing member. 
     Here, to facilitate rupturing, one corner between the two sides of the triangle may be rounded. 
     For example, when the fragile portion formed in the closing member is composed of a part of the circumference of a circle (for example, a length portion of 60% to 80% of the circumference), the length portion of 60% to 80% of the circumference is ruptured, but the length portion of 20% to 40% of the circumference remains non-ruptured, and the ruptured portion (the length portion of 60% to 80% of the circumference) is bent from a surface of the non-ruptured portion (the length portion of 20% to 40% of the circumference), thereby opening the closing member. 
     The circle may be an ellipse. 
     The gas generator of the second aspect has a control device for restricting an angle between the second surface of the closing member and the bent ruptured portion to be 5 degrees to 85 degrees when the ruptured portion of the closing member is bent and opened from the surface of the non-ruptured portion as described above. 
     Thus, when the ruptured portion is bent and opened from the surface of the non-ruptured portion, the ruptured portion is bent in a state of being inclined with respect to the second surface of the closing member (a state of being inclined at the abovementioned 5 degrees to 85 degrees). As a result, the combustion gas discharged from the opening collides with and then bypasses the ruptured portion in the inclined state before being discharged, so that mist is easily captured thereby. 
     The control device is:
     (I) a diffuser portion which is adjusted to have such a distance that a part of the bent ruptured portion of the closing member is in contact therewith; or   (II) a support portion which is formed on the second surface of the closing member at a position such as to be in contact with a part of the bent ruptured portion.   

     The control device (I) is a wall surface of the diffuser portion, or can be a convex portion integrally formed with this wall surface. 
     The distance is such that the angle of 5 degrees to 85 degrees between the ruptured portion and the second surface of the closing member is obtained when a part of the ruptured portion bent from the surface of the non-ruptured portion of the fragile portion comes into contact with the above member and the bending stops. 
     The support portion serving as the control device (II) is a convex portion formed so as to protrude from the second surface of the closing member. A formation position and a shape of the convex portion and a height thereof from the second surface are set to have the angle of 5 degrees to 85 degrees between the ruptured portion and the second surface of the closing member when bending of the ruptured portion of the fragile portion bent from the surface of the non-ruptured portion stops. 
     A different (other) aspect of the second aspect of the present invention (hereinafter referred to as “the second—(1) aspect”) can provide a gas generator including a gas generation chamber which is a combustion chamber accommodating a gas generating agent and an ignition device, 
     a closing member closing between the combustion chamber and a diffuser portion, 
     the closing member having a first surface on the side of the combustion chamber and a second surface on the back side of the first surface, 
     the closing member having a fragile portion formed such that a part thereof is ruptured when the first surface receives a pressure of gas including a combustion gas generated in the combustion chamber, and the ruptured portion is bent and opened toward the diffuser portion, 
     after the part of the closing member is ruptured along the fragile portion, the ruptured portion being bent from a non-ruptured surface and opened so that a combustion gas discharge path leading to a gas discharge port is opened, 
     a control device restricting an angle between the second surface of the closing member and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being a wall surface of the diffuser portion which is adjusted to have such a distance that the bent ruptured portion of the closing member is in contact therewith, or a support portion which is formed to protrude from the second surface of the closing member at a position such as to be in contact with the bent ruptured portion. 
     In other words, it is possible in the gas generator according to the second—(1) aspect that the gas generation chamber is a combustion chamber accommodating the gas generating agent and the ignition device, 
     the part of a closing member is ruptured and opened when the first surface receives a gas pressure of a combustion gas generated in the combustion chamber, so that a combustion gas discharge path leading to the gas discharge port is opened. 
     In the second—(1) aspect, the gas generation chamber according to the second aspect includes the combustion chamber accommodating the gas generating agent and the ignition device, and the closing member closes between the combustion chamber and the diffuser portion. 
     The fragile portion is formed in the closing member, and further the control device is provided. 
     At the time of actuation, the closing member is opened in the same manner as in the second aspect. 
     A yet different (other) aspect of the second aspect of the present invention can provide a gas generator including a gas generation chamber which is a combination of a combustion chamber accommodating a gas generating agent and an ignition device, and a pressurized gas chamber filled with a gas, 
     the combustion chamber being arranged on the side of a first end surface of a cylindrical housing, a diffuser portion which is provided with a gas discharge port being arranged on the side of a second end surface which is axially opposite to the first end surface of the cylindrical housing, and the pressurized gas chamber being arranged between the combustion chamber and the diffuser portion, 
     a first closing member closing between the combustion chamber and the pressurized gas chamber, and a second closing member closing between the pressurized gas chamber and the diffuser portion, 
     the first closing member having a first surface on the side of the combustion chamber and a second surface on the back side of the first surface, which is on the side of the pressurized gas chamber, 
     the second closing member having a first surface on the side of the pressurized gas chamber and a second surface on the back side of the first surface, which is on the side of the diffuser portion, 
     the first closing member having a fragile portion formed such that a part thereof is ruptured when the first surface receives a combustion gas pressure generated in the combustion chamber, and the ruptured portion is bent and opened toward the pressurized gas chamber, 
     after the part of the first closing member is ruptured along the fragile portion, the ruptured portion being bent from a non-ruptured portion and opened so that a gas discharge path from the combustion chamber to the pressurized gas chamber is opened, 
     a control device restricting an angle between the second surface of the first closing member and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being a support portion which is formed to protrude from the second surface of the first closing member at a position such as to be in contact with the bent ruptured portion, 
     the second closing member having a fragile portion formed such that a part thereof is ruptured when the first surface receives a gas pressure of a combustion gas generated in the combustion chamber and a pressurized gas, and the ruptured portion is bent and opened toward the diffuser portion, 
     after the part of the second closing member is ruptured along the fragile portion, the ruptured portion being bent from a non-ruptured portion and opened so that a gas discharge path from the pressurized gas chamber to the diffuser portion is opened, 
     a control device restricting an angle between the second surface of the second closing member and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being a wall surface of the diffuser portion which is adjusted to have such a distance that the bent ruptured portion of the second closing member is in contact therewith, or a support portion which is formed to protrude from the second surface of the second closing member at a position such as to be in contact with the bent ruptured portion. 
     In the third aspect, the gas generation chamber is a combination of the combustion chamber accommodating the gas generating agent and the ignition device, and the pressurized gas chamber filled with a gas. 
     The combustion chamber and the pressurized gas chamber are arranged such that the combustion chamber is arranged on the side of the first end surface of the cylindrical housing, the diffuser portion provided with the gas discharge port is arranged on the side of the second end surface which is axially opposite to the first end surface of the cylindrical housing, and the pressurized gas chamber is arranged between the combustion chamber and the diffuser portion. 
     The first closing member closes between the combustion chamber and the pressurized gas chamber, and the second closing member closes between the pressurized gas chamber and the diffuser portion. 
     At the time of actuation of the gas generator, the first closing member opens upon receipt of a combustion gas pressure generated in the combustion chamber, and the combustion gas flows into the pressurized gas chamber. 
     A pressure in the pressurized gas chamber rises due to the combustion gas flowing into the pressurized gas chamber, the second closing member opens upon receipt of the gas pressure, and then the combustion gas and the pressurized gas flow into the diffuser portion and are finally discharged from the gas discharge port. 
     The same fragile portion as that in the second aspect is formed in the first closing member. 
     The control device for the bent ruptured portion when the first closing member is ruptured at the fragile portion is a support portion (a convex portion) which is formed to protrude from the second surface of the first closing member at a position such as to be in contact with the bent ruptured portion. 
     The support portion (the convex portion) can be the same as the control device (II) in the second aspect. 
     The same fragile portion as that in the second aspect is formed in the second closing member. 
     The control device for the bent ruptured portion when the second closing member is ruptured at the fragile portion is a wall surface of the diffuser portion adjusted to have a distance such as to be in contact with the bent ruptured portion of the second closing member, or a support portion which is formed to protrude from the second surface of the second closing member at a position such as to be in contact with the bent ruptured portion. 
     The control device of the second closing member can be the same as the control device (I) or (II) in the second aspect. 
     At the time of actuation, the first closing member and the second closing member are opened in the same manner as in the second aspect. 
     A yet different (other) aspect of the second aspect of the present invention can be a gas generator including a gas generation chamber being a combination of a combustion chamber accommodating a gas generating agent and an ignition device, and a pressurized gas chamber filled with a gas, 
     the combustion chamber being arranged on the side of a first end surface of a cylindrical housing, the pressurized gas chamber being arranged on the side of a second end surface which is axially opposite to the first end surface of the cylindrical housing, and a diffuser portion being arranged between the combustion chamber and the pressurized gas chamber, 
     a first closing member closing between the combustion chamber and the diffuser portion, and a second closing member closing between the diffuser portion and the pressurized gas chamber, 
     the first closing member having a first surface on the side of the combustion chamber and a second surface on the back side of the first surface, which is on the side of the diffuser portion, 
     the first closing member having a fragile portion formed such that a part thereof is ruptured when the first surface receives a combustion gas pressure generated in the combustion chamber, and the ruptured portion is bent and opened toward the diffuser portion, 
     after the part of the first closing member is ruptured along the fragile portion, the ruptured portion being bent from a non-ruptured portion and opened so that a gas discharge path from the combustion chamber to the diffuser portion is opened, 
     a control device restricting an angle between the second surface of the first closing member and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being a member which is adjusted to have such a distance that the bent ruptured portion of the first closing member is in contact therewith, or a support portion which is formed to protrude from the second surface of the first closing member at a position such as to be in contact with the bent ruptured portion. 
     In the fourth aspect, the gas generation chamber is a combination of the combustion chamber accommodating the gas generating agent and the ignition device, and the pressurized gas chamber filled with a gas. 
     The combustion chamber and the pressurized gas chamber are arranged such that the combustion chamber is arranged on the side of the first end surface of the cylindrical housing, the pressurized gas chamber is arranged on the side of the second end surface which is axially opposite to the first end surface of the cylindrical housing, and the diffuser portion is arranged between the combustion chamber and the pressurized gas chamber. 
     At the time of actuation of the gas generator, the first closing member is opened upon receipt of a combustion gas pressure generated in the combustion chamber, and the combustion gas flows into the diffuser portion and is finally discharged from the gas discharge port. 
     Further, a pressure in the diffuser portion rises due to the combustion gas flowing into the diffuser portion. As a result, the second closing member is opened by utilizing the pressure rise, and after the pressurized gas flows into the diffuser portion, the gas is discharged from the gas discharge port. 
     A means for opening the second closing member can be directly using the gas pressure, a breaking device using the gas pressure, or the like. 
     The same fragile portion as that in the second aspect is formed in the first closing member. 
     The control device for the bent ruptured portion when the first closing member is ruptured at the fragile portion is a support portion which is formed to protrude from the second surface of the first closing member at a position such as to be in contact with the bent ruptured portion. 
     The support portion can be the same as the control device (II) in the second aspect. 
     Alternatively, the control device for the bent ruptured portion when the first closing member is ruptured at the fragile portion can be the same as the control device (I) in the first aspect. 
     At the time of actuation, the first closing member is opened in the same manner as in the second aspect. 
     The second closing member may have a fragile portion or may not have a fragile portion. 
     When the second closing member has a fragile portion, the fragile portion may be the same as or different from that in the second aspect. The different fragile portion can be, for example, a fragile portion formed radially. 
     In the gas generator of the present invention, a part (a tab) of the closing member is ruptured in a state in which a pressure in the combustion chamber having a gas generating agent is sufficiently increased, and the tab is bent and opened. Since a combustion gas flowing out from the combustion chamber through the opening collides with and then bypasses the tab before being discharged, mist is easily captured on the tab surface. 
     The gas generator of the present invention is usable for an airbag apparatus mounted on a vehicle. 
     Embodiments of Invention &lt;Gas Generator in FIGS.  1  and  2 &gt; 
     A gas generator  1  shown in (a) in  FIG. 1  has a cylindrical housing  2  and therein a gas generation chamber  5  accommodating gas generating agents  3  as a gas generating source and an igniter  4 . 
     The igniter  4  is fixed to a first end surface  2   a  of the cylindrical housing  2 , and a second end surface  2   b  of the cylindrical housing  2  on the side axially opposite to the first end surface  2   a  is closed by a closing member  6 . 
     A periphery of the closing member  6  is welded and fixed to an annular portion protruding inward from an inner circumferential wall surface of the cylindrical housing  2  at the second end surface  2   b.    
     A retainer  10  having a plurality of through holes  10   a  is disposed in the gas generation chamber  5 . The retainer  10  minimizes gaps between gas generating agents  3  charged therein and prevents contact between the gas generating agents  3  and the closing member  6 . 
     The closing member  6  shown in (a) and (b) in  FIG. 1  has a first surface  6   a  on the side of the gas generation chamber  5  and a second surface  6   b  on the back side of the first surface  6   a.    
     The closing member  6  has a U-shaped fragile portion  7  in the second surface  6   b , but may have the fragile portion  7  in the first surface  6   a.    
     The fragile portion  7  can be any portion which has lower strength than other portions and can be, for example, a groove having a V-shaped cross section or the like. 
     When the first surface  6   a  receives a pressure of gas including a combustion gas, the first surface  6   a  is ruptured along the U-shaped fragile portion  7  and a portion (a tab)  9  ruptured along the U-shaped fragile portion  7  is bent from a surface of a non-ruptured portion  8  and opens to be a gas discharge port  11  ((a) and (b) in  FIG. 2 ). 
     In (b) in  FIG. 1 , the fragile portion  7  is formed in one location, but the fragile portion can be formed in a plurality of locations so that a plurality of the tabs  9  are bent to open a plurality of the gas discharge ports  11 . 
     The gas generator  1  shown in  FIG. 1  has a control device, so that an angle (α) between the second surface  6   b  of the closing member  6  and the bent ruptured portion (the tab)  9  is restricted to be 5 degrees to 85 degrees. 
     As shown in  FIG. 3 , the angle (α) is an angle between the second surface  6   b  of the closing member  6  and an inner side surface (a surface closer to the second surface  6   b  of the closing member  6 )  9   a  of the ruptured portion (the tab)  9 . 
     The angle (α) can be selected from the above range according to components of the gas generating agent, a performance of the gas generator, and the like. 
     For example, in order to increase a gas outflow rate, the angle is increased within the range of 5 degrees to 85 degrees (preferably 60 degrees to 85 degrees). 
     For example, in order to enhance an effect of capturing mist in the gas, the angle can be reduced within the range of 5 degrees to 85 degrees (preferably 5 degrees to 40 degrees). 
     For example, in order to obtain satisfactory balance of the gas outflow rate and the mist capturing effect, the angle can be approximately an intermediate angle between the above ranges within the range of 5 degrees to 85 degrees (preferably 40 degrees to 60 degrees). 
     A control device shown in  FIG. 4  or  FIG. 5  can be used as the control device. 
     A control device  15  shown in  FIG. 4  has a rectangular main body  16 , and a first leg portion  17   a  and a second leg portion  17   b  extending in the same direction from the short sides on both ends of the rectangular main body  16 . 
     Inner side surfaces of the first leg portion  17   a  and the second leg portion  17   b  are welded and fixed to an outer circumferential surface of the cylindrical housing  2 . 
     A predetermined distance is obtained between the main body  16  and the closing member  6  (the second surface  6   b ) by adjusting the fixing positions of the first leg portion  17   a  and the second leg portion  17   b.    
     The predetermined distance is a distance to set the angle (α) shown in  FIG. 3  to be 5 degrees to 85 degrees when the ruptured tab  9  is bent at the time of actuation, a distal end portion of the tab  9  abuts against the main body  16 , and the bending is stopped. 
     A control device shown in  FIG. 5  is a convex portion (a support portion)  20  formed on the second surface  6   b  of the closing member  6 . 
     The convex portion  20  is a member separate from the closing member  6  and fixed to protrude from the second surface  6   b.    
     A shape of the convex portion  20  is not particularly limited, and the convex portion  20  can have a trapezoid cross-sectional shape such as shown in  FIG. 5 , or a triangle, square, rectangular, or irregular cross-sectional shape. 
     The convex portion  20  shown in  FIG. 5  has an inclined surface  21  facing the second surface  6   b.    
     An angle between the inclined surface  21  of the convex portion  20  and the second surface  6   b  is set such that the angle (α) shown in  FIG. 3  becomes 5 degrees to 85 degrees when the ruptured tab  9  is bent at the time of actuation, the outer side surface  9   b  of the tab  9  abuts against the inclined surface  21 , and the bending is stopped. 
     An operation of the gas generator  1  shown in (a) in  FIG. 1  will be described hereinbelow. 
     When the igniter  4  is actuated, the gas generating agents  3  in the gas generation chamber  5  are ignited and burnt to generate a combustion gas. 
     When the combustion gas applies pressure to the closing member  6  after passing through the through holes  10   a  of the retainer  10 , the U-shaped fragile portion  7  shown in (b) in  FIG. 1  is ruptured, and the tab  9  is bent from a surface of the non-ruptured portion  8  as shown in  FIG. 2 . 
     At this time, as the bending of the tab  9  is stopped by the control device  15  shown in  FIG. 4  or the control device (the convex portion  20 ) shown in  FIG. 5 , the gas discharge port  11  is opened in a state in which the angle (α) between the inner side surface  9   a  of the tab  9  and the second surface  6   b  of the closing member ( FIG. 3 ) is restricted within the range of 5 degrees to 85 degrees. 
     When the combustion gas in the gas generation chamber  5  is discharged from the gas discharge port  11 , the gas necessarily collides with and then bypasses the inner side surface  9   a  of the tab  9 . Therefore, mist adheres to the inner side surface  9   a  and is captured thereby. 
     In the gas generator  1  shown in  FIG. 1 , the combustion gas in the gas generation chamber  5  is discharged directly from the gas discharge port  11 . Therefore, the gas generator  1  is suitable in the case where a gas generating agent generating a small amount of mist is used as the gas generating agents  3 . 
     &lt;Gas Generator Shown in  FIG. 6 &gt; 
     A gas generator  50  shown in  FIG. 6  has a cylindrical housing  52 , and therein a combustion chamber  55  accommodating gas generating agents  53  as a gas generating source, and a diffuser portion  60 . 
     An igniter  54  is fixed to a first end surface  52   a  of the cylindrical housing  52 , and the diffuser portion  60  is attached to a second end surface  52   b  of the cylindrical housing  52  which is axially opposite to the first end surface  52   a.    
     A retainer  56  having a plurality of through holes  56   a  is disposed in the combustion chamber  55 . The retainer  56  minimizes gaps between the gas generating agents  53  charged therein and prevents contact between the gas generating agents  53  and a closing member  70 . 
     The diffuser portion  60  has the same shape and the same outer diameter of the radial cross section as the cylindrical housing  52  and has a circumferential surface  61  and a bottom surface  62 . 
     A plurality of gas discharge ports  63  are formed in the bottom surface  62 . 
     The closing member  70  closes between the combustion chamber  55  and the diffuser portion  60 . 
     A periphery of the closing member  70  is welded and fixed to an annular portion protruding inward from the inner circumferential wall surface of the cylindrical housing  52  at the second end surface  52   b.    
     The closing member  70  has a first surface  70   a  on the side of the combustion chamber  55  and a second surface  70   b  on the side of the diffuser portion  60 . 
     The closing member  70  can be the same as the closing member  6  shown in (b) in  FIG. 1 . The closing member  70  has a fragile portion in the second surface  70   b , but may have a fragile portion in the first surface  70   a.    
     In  FIG. 6 , the reference numeral  79  denotes a portion (a tab) where the fragile portion of the closing member  70  is ruptured at the time of actuation. 
     Preferred embodiments of the closing member  70  will be described with reference to  FIGS. 7 to 10 . 
     ( FIG. 7 ) 
     In  FIG. 7 , (a) in  FIG. 7  shows a plan view (before actuation) of the closing member as viewed from the side of the diffuser portion  60 , and (b) in  FIG. 7  is a radial sectional view (after actuation) including the second end surface  52   b  of the cylindrical housing  52  and the diffuser portion  60 . 
     As shown in (a) in  FIG. 7 , a fragile portion  77  formed in a cross shape is provided in the second surface  70   b  of the closing member  70 . The corners of the cross are rounded. 
     A circle indicated by a broken line in the central portion of the fragile portion  77  formed in a cross shape is the non-ruptured portion (a bending portion)  78  which is not ruptured. 
     In the state in (a) in  FIG. 7 , it is shown that the four gas discharge ports  63  of the diffuser portion are disposed at positions such as to axially face the fragile portion  77  formed in the cross shape. 
     As shown in (b) in  FIG. 7 , when a combustion gas pressure is received from the combustion chamber  55 , the fragile portion  77  of the closing member  70  is ruptured in a cross shape and the four tabs  79  are bent from the surface of the non-ruptured circular portion (the bending portion)  78  toward the diffuser portion  60 . 
     Thereafter, the distal end portions of the four tabs  79  abut against the bottom surface  62  of the diffuser portion  60 , thereby stopping the bending. 
     At this time, an angle between each tab  79  and the second surface  70   b  is within the range of the angle (α) (5 degrees to 85 degrees) shown in  FIG. 3 , and a distance between the second surface  70   b  and the bottom surface  62  is adjusted such that the above angle (α) is obtained. 
     The bottom surface  62  is a flat surface, but a convex portion may be formed on the bottom surface  62  at a portion where the tab  79  abuts in order to adjust the distance (the angle (α)) between the bottom surface  62  and the second surface  70   b.    
     In this way, the four tabs  79  are bent and opened (openings  58 ), and the combustion chamber  55  and the diffuser portion  60  are communicated with each other. 
     In  FIG. 7 , since the surface of the non-ruptured portion (the bending portion)  78  is located at the center portion of the closing member  70 , bending and opening proceed from a portion close to an outer circumference of the closing member  70 . 
     When the combustion gas in the combustion chamber  55  is discharged from the openings  58  into the diffuser portion  60 , the gas necessarily collides with and then bypasses the inner side surfaces  79   a  of the tabs  79 . Therefore, mist adheres to the inner side surfaces  79   a  and is easily captured thereby. 
     ( FIG. 8 ) 
     In  FIG. 8 , (a) in  FIG. 8  shows a plan view (before actuation) of the closing member as viewed from the side of the diffuser portion  60 , (b) in  FIG. 8  shows a plan view (before actuation) of the closing member of an embodiment other than that shown in (a) in  FIG. 8 , and (c) in  FIG. 8  shows a radial sectional view (after actuation) including the second end surface  52   b  of the cylindrical housing  52  and the diffuser portion  60 , this view being common to both (a) in and (b) in  FIG. 8 . 
     As shown in (a) in  FIG. 8 , the second surface  70   b  of the closing member  70  has fragile portions  77  arranged separately at four locations, each thereof being formed of three sides of a quadrangle. Corners of thereof are rounded. 
     The remaining side of the quadrangle at each fragile portion  77  formed of three sides and separately at four locations is a non-ruptured portion (a bending portion)  78 . This portion is indicated by a broken line. 
     In the state in (a) in  FIG. 8 , it is shown that the four gas discharge ports  63  of the diffuser portion are arranged at positions such as not to axially face the fragile portions  77  each formed of three sides of a quadrangle. 
     As shown in (b) in  FIG. 8 , the second surface  70   b  of the closing member  70  has fragile portions  77  arranged separately at four locations, each thereof being formed in a substantially fan shape (a fan shape has two sides each corresponding to a radius and a long circular arc between the two sides, but the two sides do not intersect at the portion radially opposite to the long circular arc). Corners thereof are rounded. 
     A short circular arc opposite to the long circular arc in each substantially fan shape arranged at four locations is the non-ruptured portion (a bending portion)  78 . 
     In the state in (b) in  FIG. 8 , it is shown that the four gas discharge ports  63  of the diffuser portion are arranged at positions such as to axially face the fragile portions  77  in a substantially fan shape. 
     As shown in (c) in  FIG. 8 , when a combustion gas pressure is received from the combustion chamber  55 , the fragile portions  77  of the closing member  70  are ruptured at four locations and the four tabs  79  are bent from the surface of the non-ruptured portion (the bending portion)  78  toward the diffuser portion  60 . 
     Thereafter, the distal end portions of the four tabs  79  abut against the bottom surface  62  of the diffuser portion  60 , thereby stopping the bending. 
     At this time, an angle between each tab  79  and the second surface  70   b  is within the range of the angle (α) (5 degrees to 85 degrees) shown in  FIG. 3 , and a distance between the second surface  70   b  and the bottom surface  62  is adjusted such that the above angle (α) is obtained. 
     The bottom surface  62  is a flat surface, but a convex portion may be formed on the bottom surface  62  at a portion where the tab  79  abuts in order to adjust the distance (the angle (α)) between the bottom surface  62  and the second surface  70   b.    
     In this way, the four tabs  79  are bent and opened (openings  58 ), and the combustion chamber  55  and the diffuser portion  60  are communicated with each other. 
     In  FIG. 8 , since the non-ruptured portion (the bending portion)  78  is located at the center portion of the closing member  70 , bending and opening proceed from a portion close to the outer circumference of the closing member  70 . 
     When the combustion gas in the combustion chamber  55  is discharged from the openings  58  into the diffuser portion  60 , the gas necessarily collides with and then bypasses the inner side surfaces  79   a  of the tabs  79 . Therefore, mist adheres to the inner side surfaces  79   a  and is easily captured thereby. 
     ( FIG. 9 ) 
     In  FIG. 9 , (a) in  FIG. 9  shows a plan view (before actuation) of the closing member as viewed from the side of the diffuser portion  60 , (b) in  FIG. 9  shows a plan view (before actuation) of the closing member of an embodiment other than that shown in (a) in  FIG. 9 , and (c) in  FIG. 9  shows a radial sectional view (after actuation) including the second end surface  52   b  of the cylindrical housing  52  and the diffuser portion  60 , this view being common to both (a) in and (b) in  FIG. 9 . 
     As shown in (a) in  FIG. 9 , the second surface  70   b  of the closing member  70  has fragile portions  77  arranged separately at four locations, each thereof being formed of three sides of a quadrangle. Corners of thereof are rounded. 
     The remaining side of the quadrangle at each fragile portion  77  formed of three sides and separately at four locations is the non-ruptured portion (a bending portion)  78 . This portion is indicated by a broken line. 
     In the state in (a) in  FIG. 9 , it is shown that the four gas discharge ports  63  of the diffuser portion are arranged at positions such as not to axially face the fragile portions  77  each formed of three sides of a quadrangle. 
     As shown in (b) in  FIG. 9 , the second surface  70   b  of the closing member  70  has fragile portions  77  arranged separately at four locations, each thereof being formed of three sides of a quadrangle. Corners thereof are rounded. 
     The remaining side of the quadrangle at each fragile portion  77  formed of three sides and separately at four locations is the non-ruptured portion (a bending portion)  78 . This portion is indicated by a broken line. 
     In the state in (b) in  FIG. 9 , it is shown that the four gas discharge ports  63  of the diffuser portion are arranged at positions such as to axially face the fragile portions  77  each formed of three sides of a quadrangle. 
     As shown in (c) in  FIG. 9 , when a combustion gas pressure is received from the combustion chamber  55 , the fragile portions  77  of the closing member  70  are ruptured at four locations and the four tabs  79  are bent from the surface of the non-ruptured portion (the bending portion)  78  toward the diffuser portion  60 . 
     Thereafter, the distal end portions of the four tabs  79  abut against the bottom surface  62  of the diffuser portion  60 , thereby stopping the bending. 
     At this time, an angle between each tab  79  and the second surface  70   b  is within the range of the angle (α) (5 degrees to 85 degrees) shown in  FIG. 3 , and a distance between the second surface  70   b  and the bottom surface  62  is adjusted such that the above angle (α) is obtained. 
     The bottom surface  62  is a flat surface, but a convex portion may be formed on the bottom surface  62  at a portion where the tab  79  abuts in order to adjust the distance (the angle (α)) between the bottom surface  62  and the second surface  70   b.    
     In this way, the four tabs  79  are bent and opened (openings  58 ), and the combustion chamber  55  and the diffuser portion  60  are communicated with each other. 
     In  FIG. 9 , since the non-ruptured portion (the bending portion)  78  is located close to an outer circumference of the closing member  70 , bending and opening proceed from a portion close to the center portion of the closing member  70 . 
     When the combustion gas in the combustion chamber  55  is discharged from the openings  58  into the diffuser portion  60 , the gas necessarily collides with and then bypasses the inner side surfaces  79   a  of the tabs  79 . Therefore, mist adheres to the inner side surfaces  79   a  and is easily captured thereby. 
     ( FIG. 10 ) 
     In  FIG. 10 , (a) in  FIG. 10  shows a plan view (before actuation) of the closing member as viewed from the side of the diffuser portion  60 , (b) in  FIG. 10  shows a radial sectional view (after actuation) including the second end surface  52   b  of the cylindrical housing  52  and the diffuser portion  60 . 
     As shown in (a) in  FIG. 10 , the second surface  70   b  of the closing member  70  has fragile portions  77  arranged separately at four locations, each thereof being formed of an irregular shape surrounded by three sides. Corners thereof are rounded. 
     Each irregular shape surrounded by three sides and formed at four locations is in a shape surrounded by a long side along the circumference of the closing member  70 , a short side along the circumference radially spaced from the long side and a connecting side radially connecting a first end of the long side and a first end of the short side. 
     A side circumferentially opposite to the connecting side of each of the irregular shapes surrounded by three sides (a side connecting a second end of the long side and a second end of the short side) is the non-ruptured portion (a bending portion)  78 . 
     In the state in (a) in  FIG. 10 , it is shown that the four gas discharge ports  63  of the diffuser portion are arranged at positions such as to axially face the fragile portions  77  of the irregular shape. 
     As shown in (b) in  FIG. 10 , when a combustion gas pressure is received from the combustion chamber  55 , the fragile portions  77  of the closing member  70  are ruptured at four locations and the four tabs  79  are bent from the surfaces of the non-ruptured portions (the bending portion)  78  toward the diffuser portion  60 . 
     Thereafter, the distal end portions of the four tabs  79  abut against the bottom surface  62  of the diffuser portion  60 , thereby stopping the bending. 
     At this time, an angle between each tab  79  and the second surface  70   b  is within the range of the angle (α) (5 degrees to 85 degrees) shown in  FIG. 3 , and a distance between the second surface  70   b  and the bottom surface  62  is adjusted such that the above angle (α) is obtained. 
     The bottom surface  62  is a flat surface, but a convex portion may be formed on the bottom surface  62  at a portion where the tab  79  abuts in order to adjust the distance (the angle (α)) between the bottom surface  62  and the second surface  70   b.    
     In this way, the four tabs  79  are bent and opened (openings  58 ), and the combustion chamber  55  and the diffuser portion  60  are communicated with each other. 
     In  FIG. 10 , since the non-ruptured portions (the bending portions)  78  are formed at intervals in the circumferential direction of the closing member  70 , the surface of each non-ruptured portion  78  is bent and opened in the circumferential direction of the closing member  70 . 
     When the combustion gas in the combustion chamber  55  is discharged from the openings  58  into the diffuser portion  60 , the gas necessarily collides with and then bypasses the inner side surfaces  79   a  of the tabs  79 . Therefore, mist adheres to the inner side surfaces  79   a  and is easily captured thereby. 
     In  FIGS. 7 to 10 , the bottom surface  62  of the diffuser portion  60  is used as the control device for the bending angle (α) of the tab  79 . However, the convex portion  20  such as shown in  FIG. 5  can be formed on the second surface  70   b  of the closing member  70  and used as the control device. 
     When the convex portion  20  such as shown in  FIG. 5  is used as the control device, the distance between the second surface  70   b  and the bottom surface  62  can be made larger than the distance shown in  FIGS. 7 to 10 . Therefore, the gas discharge port  63  can also be formed, if required, on a circumferential surface  61  of the diffuser portion  60 . 
     (3) Gas Generator Shown in  FIG. 11   
     A gas generator  100  shown in  FIG. 11  has a cylindrical housing  102 , and therein a combustion chamber  106  accommodating gas generating agents  105  as a gas generating source, a pressurized gas chamber  120  filled with a gas (argon, helium, or the like) and a diffuser portion  140  formed with a discharge port  143 . 
     A first closing member  110  closes between the combustion chamber  106  and the pressurized gas chamber  120 . 
     A periphery of the first closing member  110  is welded and fixed to an annular portion protruding inward from the inner circumferential wall surface of the cylindrical housing  102 . 
     The first closing member  110  has a first surface  110   a  on the side of the combustion chamber  106  and a second surface  110   b  on the side of the pressurized gas chamber  120 . 
     The first closing member  110  can be the same as the closing member  6  shown in (b) in  FIG. 1  or the closing member  70  shown in the plan views of  FIGS. 7 to 10 , but in this configuration, a convex portion  115  which serves as a control device and functions in the same manner as the convex portion  20  shown in  FIG. 5  is formed on the second surface  110   b  of the first closing member  110 . 
     The first closing member  110  has a fragile portion in the second surface  110   b , but a fragile portion may be formed in the first surface  110   a.    
     A second closing member  130  closes between the pressurized gas chamber  120  and the diffuser portion  140 . 
     A periphery of the second closing member  130  is welded and fixed to an annular portion protruding inward from an inner circumferential wall surface at an second end  102   b  of the cylindrical housing  102 . 
     The second closing member  130  has a first surface  130   a  on the side of the pressurized gas chamber  120  and a second surface  130   b  on the side of the diffuser portion. 
     The second closing member  130  can be the same as the closing member  6  shown in (b) in  FIG. 1 , or the closing member  70  shown in the plan views of  FIGS. 7 to 10 . 
     The second closing member  130  has a fragile portion in the second surface  130   b , but may have a fragile portion in the first surface  130   a.    
     An igniter  104  is fixed to the first end surface  102   a  of the cylindrical housing  102 . 
     A retainer  107  having a plurality of through holes  107   a  is disposed in the combustion chamber  106  so as to minimize gaps between the filled gas generating agents  105  and to prevent contact between the gas generating agents  105  and the first closing member  110 . 
     The diffuser portion  140  has the same shape and the same outer diameter of the cross section in the radial direction as the cylindrical housing  102 , and has a peripheral surface  141  and a bottom surface  142 . 
     A plurality of gas discharge ports  143  are formed in the bottom surface  142 . 
     An operation of the gas generator  100  shown in  FIG. 11  will be described hereinbelow. 
     When the igniter  104  is actuated, the gas generating agents  105  in the combustion chamber  106  are ignited and burnt to generate combustion gas. 
     When the combustion gas applies pressure to the first closing member  110  through the through holes  107   a  of the retainer  107 , the fragile portion is ruptured as shown in the cross-sectional views of  FIGS. 7 to 10 , and a tab  119  is bent from the surface of the non-ruptured portion. 
     At this time, as shown in  FIG. 5 , the bending of the tab  119  is stopped by the convex portion  115 , whereby the opening is restricted to be within the range of the angle (α) of 5 degrees to 85 degrees. 
     When the combustion gas in the combustion chamber  106  is discharged from the opening formed in the first closing member  110  into the pressurized gas chamber  120 , the combustion gas necessarily collies with and then bypasses the tab  119  before being discharged. Therefore, mist adheres to the tab  119  and is easily captured thereby. 
     As a pressure in the pressurized gas chamber  120  rises due to the combustion gas flowing thereinto, the pressure is applied to the second closing member  130 , the fragile portion is ruptured as shown in the cross-sectional views of  FIGS. 7 to 10 , and a tab  139  is bent from the surface of the non-ruptured portion. 
     At this time, as shown in the cross-sectional views of  FIGS. 7 to 10 , the bending of the tab  139  is stopped, whereby the opening is restricted to be within the range of the angle (α) of 5 degrees to 85 degrees. 
     When a mixed gas of the combustion gas and the pressurized gas in the pressurized gas chamber  120  is discharged from the opening formed in the second closing member  130  into the diffuser portion  140 , the mixed gas necessarily collides with and then bypasses the tab  139  before being discharged. Therefore, mist adheres to the tab  139  and is easily captured thereby. 
     The mixed gas discharged into the diffuser portion  140  is discharged from the gas discharge port  143 . 
     &lt;Gas Generator Shown in  FIG. 12 &gt; 
     A gas generator  200  shown in  FIG. 12  has a cylindrical housing  202  and therein a combustion chamber  206  accommodating gas generating agents  205  as a gas generating source, a pressurized gas chamber  220  charged with a gas (argon, helium, or the like) and a diffuser portion  230  formed with a discharge port  231 . 
     A first closing member  210  closes between the combustion chamber  206  and the diffuser portion  230 . 
     A periphery of the first closing member  210  is welded and fixed to an annular portion protruding inward from the cylindrical housing  202 . 
     The first closing member  210  has a first surface  210   a  on the side of the combustion chamber  206  and a second surface  210   b  on the side of the diffuser portion  230 . 
     The first closing member  210  can be the same as the closing member  6  shown in (b) in  FIG. 1  or the closing member  70  shown in the plan views of  FIGS. 7 to 10 , but in this configuration, a convex portion (not shown) which serves as a control device and functions in the same manner as the convex portion  20  shown in  FIG. 5  is formed on the second surface  210   b.    
     The first closing member  210  has a fragile portion in the second surface  210   b , but a fragile portion may be formed in the first surface  210   a.    
     A second closing member  221  closes between the pressurized gas chamber  220  and the diffuser portion  230 . 
     A periphery of the second closing member  221  is welded and fixed to an annular portion protruding inward from an inner circumferential wall surface of the cylindrical housing  202 . 
     Since the second closing member  221  is not required to capture mist, the second closing member does not have a fragile portion such as that in the first closing member  210 , but the second closing member may have a fragile portion (for example, a fragile portion formed radially) to facilitate rupturing. 
     An igniter  204  is fixed to the first end surface  202   a  of the cylindrical housing  202 . 
     A retainer  207  having a plurality of through holes  207   a  is disposed in the combustion chamber  206  so as to minimize gaps between the filled gas generating agents  205  and to prevent contact between the gas generating agents  205  and the first closing member  210 . 
     A plurality of gas discharge ports  231  is formed in the diffuser portion  230 . 
     &lt;Gas Generators Shown in  FIGS. 13 to 16 &gt; 
     A preferred embodiment of the gas generator shown in  FIG. 12  will be described with reference to  FIG. 13 . 
     In a gas generator  300  shown in  FIG. 13 , a combustion chamber  330 , a diffuser portion  340 , and a pressurized gas chamber  350  are arranged in a cylindrical housing  310 . 
     The cylindrical housing  310  includes a combustion chamber housing  311  and a pressurized gas chamber housing  312 , but the entire cylindrical housing may be formed of a single housing. 
     In the combustion chamber housing  311 , an electric igniter  325  is fixed to an opening of a first end portion  311   a.    
     A second end portion  312   a  of the pressurized gas chamber housing  312  is closed (a closing surface  313 ). 
     An opening of a second end portion  311   b  of the combustion chamber housing  311  and an opening of a first end portion  312   b  of the pressurized gas chamber housing  312  are welded and integrated at a joining portion  314 . 
     The cylindrical housing  310  (the combustion chamber housing  311  and the pressurized gas chamber housing  312 ) is made of iron, stainless steel or the like. 
     A gas such as argon, helium, or the like is filled in the pressurized gas chamber  350  under a high pressure. 
     The gas is filled from a gas filling hole in the closing surface  313  of the pressurized gas chamber housing  312 . 
     A pin  315  is inserted into the gas filling hole after the gas is filled, and then the pin  315  and the closing surface  313  are welded together to close the gas filling hole. 
     A second closing device  341  closes between the pressurized gas chamber  350  and the diffuser portion  340 . 
     The second closing device  341  includes a fixing portion  342  and a rupturable plate  347  welded and fixed to the fixing portion  342 . 
     The fixing portion  342  has an annular plate surface  343  extending radially inward from the second end portion  311   b  of the combustion chamber housing  311 , and a cylindrical wall  344  extending from the inner peripheral portion of the annular plate surface  343  toward the diffuser portion  340  (see  FIG. 14 ). 
     A boundary between the annular plate surface  343  and the cylindrical wall  344  of the fixing portion  342  is a curved surface. 
     The annular plate surface  343  of the fixing portion  342  has an annular groove  348  in the surface on the side of the pressurized gas chamber  350  (see  FIG. 14 ). 
     The rupturable plate  347  is made of iron, stainless steel or the like. A periphery of the rupturable plate  347  is abutted against the annular groove  348  formed in the annular plate surface  343  of the fixing portion  342 , and in this state, the rupturable plate  347  is welded and fixed at the abutting portion. 
     At this time, a pressure of the pressurized gas filled in the pressurized gas chamber  350  deforms the rupturable plate  347  toward the diffuser portion  340  along the curved surface of the boundary between the annular plate surface  343  and the cylindrical wall  344 . Therefore, concentration of stress on the rupturable plate at the boundary is avoided by the curved surface. As a result, the pressure resistance of the rupturable plate is enhanced. 
     The diffuser portion  340  is a space into which a gas flows from the pressurized gas chamber  350  and a combustion gas flows from the combustion chamber  330  at the time of actuation. 
     In  FIG. 14 , a plurality of gas discharge ports  329  are formed in the combustion chamber housing  311  facing the diffuser portion  340 . 
     The plurality of the gas discharge ports  329  are formed at equal intervals in the circumferential direction of the combustion chamber housing  311 . 
     A known filter can be disposed at a position such as to cover the gas discharge ports  329  of the diffuser portion  340  from the inside. 
     A breaking device  331  including a base portion  332  and a rod  333  extending from the base portion  332  to the rupturable plate  347  is disposed between the diffuser portion  340  and the combustion chamber  330 . 
     In the breaking device  331  shown in  FIGS. 13 to 16 , the base portion  332  and the rod  333  are integrated. 
     The base portion  332  includes a disk portion  335  having a plurality of through holes  334  in the thickness direction and a cylindrical wall surface  336  extending from the outer periphery of the disk portion  335  toward the igniter  325 . 
     An outer circumferential surface  336   a  of the cylindrical wall surface  336  is abutted against an inner circumferential wall surface  311   c  of the combustion chamber housing  311  so that the base portion  332  slides in the axis X direction. Since a length of the cylindrical wall surface  336  in the axial direction (the axis X direction) is greater than a thickness of the disk portion  335 , the rod  333  does not tilt with respect to the axis X, and the base portion  332  slides parallel to the axis X direction. 
     A sealant for maintaining airtightness in the combustion chamber  330  is applied between the outer circumferential surface  336   a  of the cylindrical wall surface  336  and the inner circumferential wall surface  311   c  of the combustion chamber housing  311 . 
     The rod  333  has a rod main body  337  extending from the base portion  332  and an enlarged diameter portion  338  which is enlarged radially outward from the rod main body  337 . 
     A diameter of the enlarged diameter portion  338  is smaller than the inner diameter of the cylindrical wall  344 . 
     A surface  338   a  (see  FIG. 14 ) of the enlarged diameter portion  338  of the rod  333  has a shape curved toward the center as shown in  FIGS. 13 to 15 , but it may be, for example, a rectangular recessed portion. 
     The breaking device  331  and the second closing device  341  are arranged such that the enlarged diameter portion  338  which is the distal end portion of the rod  333  is surrounded by a cylindrical wall  344  of the fixing portion  342  before actuation. At this time, a slight gap is formed between the outer circumferential portion of the enlarged diameter portion  338  and the inner circumferential surface  344   a  of the cylindrical wall  344 . 
     A first closing member  360  is disposed at a position in contact with an annular distal end portion  336   b  of the cylindrical wall surface  336  of the base portion  332 . 
     The first closing member  360  includes a circular main body  361  and an annular wall  362  extending from a peripheral portion of the circular main body  361 . 
     The circular main body  361  has a first surface  361   a  on the side of the combustion chamber  330  and a second surface  361   b  on the side of the diffuser portion  340 . 
     A sealant for maintaining airtightness in the combustion chamber  330  is applied between the annular wall  362  and an inner circumferential wall surface  311   c  of the combustion chamber housing  311 . 
     The first closing member  360  can be the same as the closing member  6  shown in (b) in  FIG. 1 , or the closing member  70  shown in the plan views of  FIGS. 7 to 10 . 
     In the combustion chamber  330 , the igniter  325  is fixed to the first end portion  311   a , and the opposite side in the axis X direction is partitioned by the base portion  332 . 
     A prescribed amount of gas generating agents  326  is filled in the combustion chamber  330 . 
     A protrusion  317  for restricting movement and a reduced diameter portion  318  for stopping movement are provided, in the order of the above description on the inner circumferential wall surface  311   c  of the cylindrical housing from the combustion chamber  330  to the diffuser portion  340 . 
     Next, an operation of the gas generator  300  shown in  FIG. 13  will be described with reference to  FIGS. 13 to 15 . 
     The gas generating agents  326  are ignited and burnt by combustion products generated by the actuation of the igniter  325 , and a high-temperature combustion gas is generated. 
     When a pressure in the combustion chamber  330  is raised by the combustion gas, the fragile portion of the first closing member  360  is ruptured as shown in the cross-sectional views of  FIGS. 7 to 10 , and the tab  365  is bent from the surface of the non-ruptured portion. 
     At this time, as shown in  FIG. 15 , the distal end portion of the bent tab  365  abuts against a surface (a control device) of the base portion  332  having no through holes  334  and the bending is stopped, whereby opening (an opening  366 ) is restricted to be within the range of the angle (α) of 5 degrees to 85 degrees. 
     When the combustion gas in the combustion chamber  330  passes through the opening  366  formed in the first closing member  360 , the combustion gas necessarily collides with the tab  365 . Therefore, mist adheres to the tab  365  and is easily captured thereby. 
     Where the tab  365  is thus bent to form the opening  366  and the gas is discharged to the diffuser portion  340 , the base portion  332  of the breaking device  331  passes over the protrusion  317  and moves while sliding on the inner circumferential wall surface  311   c  of the combustion chamber housing in the axis X direction. At this time, the first closing member  360  also moves in the axis X direction. 
     Thereafter, the base portion  332  collides with a stepped portion (the reduced diameter portion)  318  with a reduced internal diameter and stops. By that time, since the enlarged diameter portion  338  of the rod  333  collides with and ruptures the rupturable plate  347 , the gas in the pressurized gas chamber  350  flows into the diffuser portion  340  through an annular gap  339  between an opening of the rupturable plate  347  (the inner circumferential surface  344   a  of the cylindrical wall  344 ) and the rod main body  337  ( FIG. 16 ). 
     When the base portion  332  stops, the movement of the first closing member  360  also stops ( FIG. 16 ). 
     In the state shown in  FIG. 16 , in the case that, when the gas flows into the diffuser portion  340  from the annular gap  339 , the breaking device  331  (the base portion  332 ) receives pressure, passes over the protrusion  317  and returns toward the combustion chamber  330  and the enlarged diameter portion  338  is located within the inner circumferential surface  344   a  of the cylindrical wall  344 , a cross sectional area of the annular gap  339  changes, and a stable gas flow rate cannot be maintained. 
     However, since the gas generator  300  has the protrusion  317 , as shown in  FIGS. 14 to 16 , the breaking device  331  (the base portion  332 ) does not pass over the protrusion  317  and return toward the combustion chamber  330 . As a result, the cross-sectional area of the annular gap  339  is kept constant. 
     Further, since the fixing portion  342  has the cylindrical wall  344 , even when a center axis of the rod  333  is displaced when the breaking device  331  (the base portion  332 ) slides at the time of actuation, the cylindrical wall  344  preferably exerts the guide function, and thereby the rod reliably collides with the rupturable plate  347 . 
     The combustion gas and the pressurized gas flowing into the diffuser portion  340  are discharged from the gas discharge port  329 . 
     Preferred embodiments of the gas generator  300  shown in  FIGS. 13 to 16  are described hereinbelow. 
     (1) A gas generator including the cylindrical housing  310  in which the ignition device (the igniter)  325  is fixed to an opening of the first end portion  311   a  and the second end portion  312   a , on the axially opposite side to the first end portion, is closed, 
     the combustion chamber  330  provided with the ignition device  325 , the diffuser portion  340  provided with the gas discharge port  329  and the pressurized gas chamber  350  being arranged inside the housing in the above described order from the first end portion  311   a,    
     the closing device  341  including the fixing portion  342  and a rupturable plate  347  fixed to the fixing portion  342 , the closing device  341  closing between the pressurized gas chamber  350  and the diffuser portion  340 , 
     the breaking device  331  for the rupturable plate  347  including the base portion  332 , whose outer circumferential surface is abutted against an inner circumferential wall surface of the cylindrical housing  310 , and the rod  333 , which extends from the base portion  332  toward the rupturable plate  347 , the breaking device  331  being arranged between the combustion chamber  330  and the diffuser potion  340 , 
     the base portion  332  including the disk portion  335  which has a plurality of the through holes  334  in the thickness direction, and the cylindrical wall surface  336  which extends from an outer periphery of the disk portion  335  toward the igniter  325 , 
     the first closing member  360  being disposed at a position such as to abut against the annular distal end portion  336   b  of the cylindrical wall surface  336  of the base portion  332 , 
     the first closing member  360  including the circular main body  361  and the annular wall  362  which extends from the peripheral end of the circular main body  361 , 
     the circular main body  361  having the first surface  361   a  on the side of the combustion chamber  330  and the second surface  361   b  on the side of the diffuser portion  340 , 
     the first closing member  360  having the fragile portion formed such that a part thereof is ruptured when the first surface  361   a  receives a gas pressure of the combustion gas generated in the combustion chamber  330  and the ruptured portion is bent toward the diffuser portion  340  to be opened, 
     after the part of the first closing member  360  is ruptured along the fragile portion, the ruptured portion being bent from the surface of the non-ruptured portion and opened so that a gas discharge path to the diffuser portion  340  is opened, 
     the control device restricting an angle between the second surface  361   b  of the first closing member  360  and the bent ruptured portion to be 5 degrees to 85 degrees, 
     the control device being a surface of the disk portion  335  of the base portion  332  in part where no through holes are formed, the control device being adjusted to have such a distance that the bent ruptured portion of the first closing member  360  abuts against the surface of the disk portion  335 , 
     the fixing portion  342  of the closing device  341  including the annular plate surface  343 , which extends inward from the inner circumferential wall surface of the cylindrical housing  310  in the radial direction, and the cylindrical wall  344 , which extends from the inner periphery of the annular plate surface portion  343  toward the diffuser portion  340 , 
     the rupturable plate  347  of the closing devise  341  being welded and fixed to the annular plate surface  343  of the fixing portion  342  from the pressurized gas chamber  350   
     the breaking device  331  being disposed such that the distal end portion of the rod  333  is surrounded by the cylindrical wall  344  of the fixing portion  342  of the closing device  341 . 
     (2) The gas generator according to the above (1), wherein 
     the breaking device includes the base portion  332  and the rod  333  extending from the base portion  332  toward the rupturable plate  347 , 
     the rod  333  has the rod main body  337  extending from the base portion and the enlarged diameter portion  338  in which the distal end portion of the rod main body  337  is enlarged in diameter in the radial direction, and 
     the enlarged diameter portion  338  is disposed so as to be surrounded by the cylindrical wall  344  of the fixing portion of the closing device  341 . 
     The invention 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.