TECHNICAL FIELD  
       [0001]     The present invention relates to an inflator, and particularly to an inflator for use in inflating an inflatable vehicle occupant protection device.  
       BACKGROUND OF THE INVENTION  
       [0002]     A conventional inflator for inflating an inflatable vehicle occupant protection device includes a container having a storage chamber. Inflation fluid under pressure is stored in the storage chamber. An igniter assembly is associated with the container and is actuatable for heating the inflation fluid in the storage chamber to increase the fluid pressure in the storage chamber. The increased fluid pressure ruptures a burst disk. The ruptured burst disk defines an outlet opening through which the inflation fluid flows.  
         [0003]     U.S. Pat. No. 5,529,333 describes an inflator for inflating an air bag that includes a container that defines a storage chamber. The container has an opening that leads to the storage chamber. A plug member is received in the opening of the container and closes the opening of the container. Two passages extend through the plug member. A first passage through the plug member enables inflation fluid to flow from the storage chamber toward an air bag. A wall portion of the plug member closes the first passage. The wall portion of the plug member includes a break away center. An actuator is actuatable for opening the break away center of the wall portion of the plug member to form an outlet opening through which inflation fluid flows. A second passage through the plug member is provided for filling the storage chamber with inflation fluid. A ball is located in the second passage for preventing inflation fluid from flowing out of the storage chamber of the container through the second passage of the plug member.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention relates to an inflator comprising structure defining a chamber. First and second passages extend through the structure to the chamber. A burst disk closes the first passage. The inflator also comprises a fill valve assembly having a valve housing and a valve member. The valve housing is received in the second passage and defines a fill passage. A fluid is stored under pressure in the chamber. An igniter is actuatable for opening the burst disk for enabling fluid to flow out of the chamber through the first passage. The valve member enables flow of the fluid through the fill passage of the valve housing into the chamber and prevents flow out of the chamber through the fill passage.  
         [0005]     According to another aspect, the present invention relates to an inflator comprising structure defining a chamber. First and second passages extend through the structure to the chamber. A fluid is stored under pressure in the chamber. A device closes the first passage and is actuatable for enabling fluid to flow out of the chamber through the first passage. The inflator also comprises a fill valve having a valve housing, a valve member, and a plug member. The valve housing is received in the second passage and defines a fill passage. The valve member enables flow of the fluid through the fill passage of the valve housing into the chamber and prevents flow out of the chamber through the fill passage. The plug member seals the fill passage of the valve housing after the fluid is introduced into the chamber through the fill passage. The plug member is spaced away from the valve member outward of the chamber. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     The foregoing and other features of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which:  
         [0007]      FIG. 1  illustrates a vehicle safety system including an inflator constructed in accordance with the present invention;  
         [0008]      FIG. 2  is a cross-section of the inflator of  FIG. 1  in a non-actuated condition;  
         [0009]      FIG. 3  is an enlarged view of a portion of  FIG. 2 ;  
         [0010]      FIG. 4  is a partially exploded view of the portion of the inflator shown in  FIG. 3 ;  
         [0011]      FIG. 5  is a cross-section of the inflator of  FIG. 1  in an actuated condition; and  
         [0012]      FIG. 6  is an enlarged view of a portion of an inflator constructed in accordance with a second embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]      FIG. 1  illustrates a vehicle safety system  10  including the inflator  12  constructed in accordance with the present invention. The inflator  12  of the present invention is for use in inflating an inflatable vehicle occupant protection device of the vehicle safety system  10 . The inflatable vehicle occupant protection device of  FIG. 1  is an inflatable curtain  14 . Alternatively, the inflatable vehicle occupant protection device may include an inflatable air bag, an inflatable seat belt, an inflatable knee bolster, an inflatable headliner, or a knee bolster operated by an inflatable air bag.  
         [0014]     The inflatable curtain  14  of  FIG. 1  is in a deflated condition and is stored within a housing  16 . The inflatable curtain  14 , in the deflated condition, and the housing  16  have an elongated configuration and are mounted to a vehicle  18  in a location adjacent both the side structure of the vehicle and a roof  20  of the vehicle. The side structure of the vehicle  18  includes an A-pillar  22 , a B-pillar  24 , a C-pillar  26 , and side windows  28  and  30 .  FIG. 1  shows four brackets  32  securing the housing  16  and the inflatable curtain  14  to the side structure of the vehicle  18 .  
         [0015]     In the illustrated embodiment, a fill tube  34  connects the inflator  12  of the present invention to the inflatable curtain  14 . The inflator  12  is in fluid communication with the inflatable curtain  14  through the fill tube  34 . Upon actuation of the inflator  12 , inflation fluid flows through the fill tube  34  and into the inflatable curtain  14 . In response to receiving the inflation fluid, the inflatable curtain  14  deploys from the deflated condition to an inflated condition to cover portions of the side structure of the vehicle, such as side windows  28  and  30 .  
         [0016]     As shown in  FIG. 2 , the inflator  12  includes a tubular metal body portion  40 . The body portion  40  includes cylindrical inner and outer surfaces  42  and  44 , respectively. The inner and outer surfaces  42  and  44  are centered on a longitudinal axis A. The body portion  40  of the inflator  12  also has opposite first and second open ends  46  and  48 , respectively.  
         [0017]     An igniter endcap  50  closes the first open end  46  of the body portion  40 . The igniter endcap  50  includes an annular, radially extending peripheral portion  52 . An outer diameter of the peripheral portion  52  of the igniter endcap  50  is approximately equal to a diameter of the outer surface  44  of the body portion  40 . The peripheral portion  52  of the igniter endcap  50  is affixed to the body portion  40  at the first open end  46 . The peripheral portion  52  of the igniter endcap  50  may be welded to or crimped to the body portion  40  at the first open end  46 .  FIG. 2  shows the peripheral portion  52  of the igniter endcap  50  welded to the body portion  40  at the first open end  46 .  
         [0018]     The igniter endcap  50  also includes an axially protruding central portion  54 . The central portion  54  includes first and second annular, axially extending portions  56  and  58 , respectively. The first annular, axially extending portion  56  is disposed adjacent to the peripheral portion  52  and has a diameter that is greater than a diameter of the second annular, axially extending portion  58 . A tapered portion  60  connects the first and second annular, axially extending portions  56  and  58 . A central flange  62  extends radially inwardly from an end of the second annular, axially extending portion  58  opposite the tapered portion  60 . A radially inner surface  64  of the central flange  62  defines a passage  66  through the igniter endcap  50 .  
         [0019]     An igniter  70  is secured to the igniter endcap  50 . The igniter  70  includes a portion  72  containing a pyrotechnic material (not shown) and a resistive wire (not shown) for igniting the pyrotechnic material. The igniter  70  also includes leads  74  for connecting the resistive wire of the igniter to electronic circuitry  76  ( FIG. 1 ) of a vehicle safety system  10 . The electronic circuitry  76  includes a sensor  78  for sensing a deployment condition for which inflation of the inflatable curtain  14  is desired. When a deployment condition is sensed, the igniter  70  receives an actuation signal through the leads  74 . The igniter  70  is responsive to the actuation signal for actuating the inflator  12  to provide inflation fluid to the inflatable curtain  14 .  
         [0020]     An isolation disk  80  is affixed to the central flange  62  of the igniter endcap  50  on a side opposite to the igniter  70 . The isolation disk  80  closes and seals the passage  66  through the igniter endcap  50 . Preferably, the isolation disk  80  is welded to the central flange  62  of the igniter endcap  50 .  
         [0021]     The inflator  12  also includes a diffuser endcap  82 . The diffuser endcap  82  closes the second open end  48  of the body portion  40  of the inflator  12 . The diffuser endcap  82  includes a tubular end portion  84 . The tubular end portion  84  includes inner and outer surfaces  86  and  88 , respectively. The outer surface  88  of the tubular end portion  84  of the diffuser endcap  82  has a diameter that is equal to the diameter of the outer surface  44  of the body portion  40 . An annular end surface  90  of the tubular end portion  84  connects the inner and outer surfaces  86  and  88 . A passage  92  ( FIG. 4 ) extends radially through the tubular end portion  84  of the diffuser endcap  82 . As shown in  FIG. 4 , the passage  92  defines an opening  94  on the outer surface  88  of the diffuser endcap  82  and an opening  96  on the inner surface  86  of the diffuser endcap.  
         [0022]     An annular wall portion  100  of the diffuser endcap  82  extends radially inwardly from the tubular end portion  84  at an end of the tubular end portion opposite end surface  90 . The annular wall portion  100  includes inner and outer surfaces  102  and  104 , respectively, and terminates at a cylindrical end surface  106 . The inner surface  102  of the annular wall portion  100  joins with and extends perpendicular to the inner surface  86  of the tubular end portion  84  of the diffuser endcap  82 . The outer surface  104  of the annular wall portion  100  joins with and extends perpendicular to the outer surface  88  of the tubular end portion  84  of the diffuser endcap  82 .  
         [0023]     A tubular discharge portion  110  of the diffuser endcap  82  extends axially away from the annular wall portion  100 . The tubular discharge portion  110  includes cylindrical inner and outer surfaces  112  and  114 , respectively. The inner surface  112  of the tubular discharge portion  110  extends axially from the cylindrical end surface  106  of the annular wall portion  100 . The outer surface  114  of the tubular discharge portion  110  joins with and extends perpendicular to the outer surface  104  of the annular wall portion  100 . The inner surface  112  of the tubular discharge portion  110  and the cylindrical end surface  106  of the annular wall portion  100  collectively define a passage  116  through which inflation fluid flows. Inflation fluid flows axially, i.e., in a direction that is parallel to the longitudinal axis A of the body portion  40  of the inflator  12 , from the tubular discharge portion  110  of the diffuser endcap  82  of  FIGS. 2-4 .  
         [0024]     A metal burst disk  120  closes the passage  116  of the diffuser endcap  82 . The burst disk  120  has a domed central portion  122  and a radially outwardly extending flange portion  124  that is affixed to the inner surface  102  of the annular wall portion  100  of the diffuser endcap  82 . Preferably, the burst disk  120  is welded to the annular wall portion  100 . When the flange portion  124  of the burst disk  120  is affixed to the inner surface  102  of the annular wall portion  100 , the domed central portion  122  of the burst disk  120  is located in the passage  116 . The burst disk  120  is designed to rupture when subjected to a predetermined differential pressure. In a preferred embodiment, the burst disk  120  is designed to rupture when exposed to a differential pressure of approximately 12,000 pounds per square inch (psi). When the burst disk  120  ruptures, an outlet opening  126  ( FIG. 5 ) is formed in the burst disk  120 .  
         [0025]     The body portion  40 , the igniter endcap  50 , and the diffuser endcap  82  collectively define a chamber  130 . The chamber  130  extends axially along the longitudinal axis A between the igniter endcap  50  and the diffuser endcap  82 . The inner surface  42  of the body portion  40  and the inner surface  86  of the tubular end portion  84  of the diffuser endcap  82  define a radial outer boundary of the chamber  130 .  
         [0026]     The inflator  12  also includes a fill valve assembly  140  through which the chamber  130  is filled. Details of the fill valve assembly  140  are described with reference to  FIGS. 3 and 4 . The fill valve assembly  140  includes a valve housing  142  and a valve member  144 . The valve housing  142  has a main body portion  146 , an outer portion  148 , and an inner portion  150 . The main body portion  146  of the valve housing  142  is located between the outer and inner portions  148  and  150 . The main body portion  146  of the valve housing  142  includes a cylindrical outer surface  152 . A fill passage  154  extends through the main body portion  146 . As shown in  FIG. 4 , the fill passage  154  includes a large diameter portion  156 , a tapered portion  158 , and a smaller diameter portion  160 . The large diameter portion  156  of the fill passage  154  is located nearest the outer portion  148  of the valve housing  142 . The tapered portion  158  of the fill passage  154  is located nearest the inner portion  150  of the valve housing  142 . The smaller diameter portion  160  is located between the large diameter portion  156  and the tapered portion  158  of the fill passage  154 .  
         [0027]     The outer portion  148  of the valve housing  142  is the widest part of the valve housing. The outer portion  148  includes a tapered shoulder portion  162  and a tubular outer portion  164 . The tapered shoulder portion  162  extends radially outwardly of the main body portion  146  of the valve housing  142  as it extends axially away from the main body portion. The tapered shoulder portion  162  includes outer and inner surfaces  166  and  168  ( FIG. 4 ), respectively. The outer surface  166  joins with the cylindrical outer surface  152  of the main body portion  146 . The inner surface  168  of the tapered shoulder portion  162  leads to the large diameter portion  156  of the fill passage  154 . The tubular outer portion  164  extends axially away from the tapered shoulder portion  162  in a direction opposite to the main body portion  146 . The tubular outer portion  164  includes an outer surface  170  ( FIG. 4 ) having a diameter approximately twice the diameter of the cylindrical outer surface  152  of the main body portion  146 . An inner diameter of the tubular outer portion  164  defines a mouth  172  that leads to the fill passage  154  of the valve housing  142 .  
         [0028]     The inner portion  150  of the valve housing  142  is generally tubular and terminates at an end surface  174  ( FIG. 4 ). The inner portion  150  includes cylindrical outer and inner surfaces  176  and  178  ( FIG. 4 ), respectively. The outer surface  176  of the inner portion  150  of the valve housing  142  is coaxial with and has a diameter that is equal to the cylindrical outer surface  152  of the main body portion  146 . The inner surface  178  of the inner portion  150  defines a chamber  180 . The inner portion  150  of the valve housing  142  includes four cutouts  182 , one of which is shown in full in  FIG. 4 . The cutouts  182  are located adjacent to the end surface  174  of the inner portion  150 . The four cutouts  182  separate four finger portions  184  of the inner portion  150  of the valve housing  142 .  FIG. 4  shows two of the four finger portions  184 .  
         [0029]     The valve member  144  of the fill valve assembly  140  is a check ball. The check ball  144  is formed from an elastomer. Preferably, the check ball  144  is made from either VITON elastomer (trademark of E.I. DuPont de Nemours &amp; Co.) or a synthetic rubber made from the polymerization of butadiene and sodium. The check ball  144  is placed in the chamber  180  of the inner portion  150  of the valve housing  142 . The four finger portions  184  of the inner portion  150  of the valve housing  142  are bent inwardly toward one another to the positions shown in  FIG. 3  so as to form a cage for retaining the check ball  144  in the chamber  180 . The cutouts  182  between the finger portions  184  enable fluid flow into and out of the chamber  180 .  
         [0030]     The fill valve assembly  140  is inserted into the passage  92  in the diffuser endcap  82  until the outer surface  166  of the tapered shoulder portion  162  engages the outer surface  88  of the tubular end portion  84  of the diffuser endcap  82 . The valve housing  142  is then affixed to the diffuser endcap  82 . Preferably, the tapered shoulder portion  162  of the outer portion  148  of the valve housing  142  is welded to the tubular end portion  84  of the diffuser endcap  82 . When affixed to the diffuser endcap  82 , the inner portion  150  of the valve housing  142  and the check ball  144  are located in the chamber  130 .  
         [0031]     A combustible gas mixture  186  ( FIG. 2 ) is stored in the chamber  130 . The combustible gas mixture  186  preferably includes an inert gas, hydrogen, and oxygen or an inert gas, hydrogen and air. The inert gas may be argon, nitrogen, or any suitable inert gas. Trace amounts of helium may be added to the combustible gas mixture  186  to aid in leak detection. The combustible gas mixture  186  is stored under pressure in the chamber  130  of the inflator  12 . Preferably, the pressure of the stored combustible gas mixture  186  in the chamber  130  of the inflator  12  is 6,000 to 7,000 pounds per square inch (psi).  
         [0032]     When the fill valve assembly  140  is oriented as shown in  FIG. 3  and there is no difference between the air pressure in the chamber  130  and atmospheric pressure, gravity acts on the check ball  144  and the check ball lies on the bent finger portions  184  of the valve housing  142 . To fill the chamber  130  of the inflator  12  with the combustible gas mixture  186 , a filling tube (not shown) of a filling device (not shown) is inserted into the mouth  172  of the outer portion  148  of the valve housing  142 . The combustible gas mixture  186  flows through the fill passage  154  of the valve housing  142  of the fill valve assembly  140  and into the chamber  180  of the inner portion  150  of the valve housing  142  of the fill valve assembly  140 . The combustible gas mixture  186  then flows through the cutouts  182  into the chamber  130  of the inflator  12 .  
         [0033]     As the pressure of the combustible gas mixture  186  stored in the chamber  130  of the inflator  12  increases, the gas pressure in the chamber  130  tends to force the check ball  144  upwardly, as viewed in  FIG. 3 , toward the main body portion  146  of the valve housing  142  to close the fill passage  154 . The flow of the combustible gas mixture  186  through the fill passage  154  toward the chamber  130  moves the check ball  144  away from the main body portion  146  and enables flow into the chamber  130 . When the flow of the combustible gas mixture  186  through the fill passage  154  toward the chamber  130  ceases, the check ball  144  moves upwardly, as viewed in  FIG. 3 , into the tapered portion  158  of the fill passage  154  and seats against the main body portion  146  of the valve housing  142  to close the fill passage. The check ball  144  forms a seal against the main body portion  146  of the valve housing  142  to prevent the escape of the stored combustible gas mixture  186  from the chamber  130  through the fill passage  154 .  
         [0034]     When the filling tube (not shown) of the filling device (not shown) is removed from the mouth  172  of the tubular outer portion  164  of the outer portion  148  of the valve housing  142 , any of the combustible gas mixture  186  that is present in the fill passage  154  of the valve housing  142  dissipates into the atmosphere. Alternatively, the fill passage  154  may be aspirated to remove any of the combustible gas mixture  186  that is present in the fill passage. A metal seal plug  188  is then secured to the valve housing  142  to close and seal the large diameter portion  156  of the fill passage  154 . The metal seal plug  188 , prior to being secured to the valve housing  142 , is a spherical ball, as shown in  FIG. 4 . The metal seal plug  188  may have a shape other than spherical.  
         [0035]     To secure the metal seal plug  188  to the valve housing  142 , the inflator  12  is oriented so that the outer portion  148  of the valve housing  142  is located above the check ball  144 , as is shown in  FIG. 3 . The metal seal plug  188  is placed in the mouth  172  of the outer portion  148  of the valve housing  142  and gravity causes the metal seal plug  188  to rest on the inner surface  168  of the tapered shoulder portion  162  of the outer portion  148 . The metal seal plug  188  is then heated until a portion of the metal seal plug melts. Since the inner surface  168  of the tapered shoulder portion  162  leads to the large diameter portion  156  of the fill passage  154 , the melted portion of the metal seal plug  188  flows along the inner surface  168  and into the large diameter portion  156  of the fill passage  154 . When the heat is removed from the metal seal plug  188 , the metal seal plug  188  bonds to the valve housing  142  to close and seal the fill passage  154 . A portion of the metal seal plug  188  is located within and closes the large diameter portion  156  of the fill passage  154  and a portion of the metal seal plug is located outside of the fill passage and abuts the inner surface  168 .  
         [0036]     The fill passage  154  spaces the metal seal plug  188  away from the check ball  144  and thus, away from the combustible gas mixture  186  in the chamber  130 . The spacing of the metal seal plug  188  away from the chamber  130  and the seal of the check ball  144  over the fill passage  154  enable the metal seal plug to be safely heated without igniting the combustible gas mixture  186 .  
         [0037]     When the igniter  70  of the inflator  12  receives the actuation signal from the electronic circuitry  76  of the vehicle safety system  10 , the igniter  70  is actuated. Combustion products, including a shock wave, from actuation of the igniter  70  travel through the passage  66  in the igniter endcap  50 , rupture the isolation disk  80 , and enter the chamber  130 . The combustion products heat and ignite the combustible gas mixture  186  that is stored under pressure within the chamber  130 . The resulting combustion of the combustible gas mixture  186  produces inflation fluid, which is further heated by the combustion of the combustible gas mixture. The heating and ignition of the combustible gas mixture  186  increases the pressure within the chamber  130 . When the predetermined differential pressure across the burst disk  120  is reached, the burst disk  120  is ruptured and the outlet opening  126  is formed through the ruptured burst disk. Inflation fluid passes through the outlet opening  126 , through the passage  116  in the diffuser endcap  82 , and into the fill tube  34  for inflating the inflatable curtain  14 .  FIG. 5  illustrates an actuated inflator  12  including an actuated igniter  70 , a ruptured isolation disk  80 , and a ruptured burst disk  120 . The metal seal plug  188  and the check ball  144  of the fill valve assembly  140  prevent inflation fluid from passing through the fill passage  154  of the valve housing  142 .  
         [0038]      FIG. 6  is an enlarged view of a portion of an inflator  12 ′ constructed in accordance with a second embodiment of the present invention. Structures of  FIG. 6  that are the same as or similar to structures of  FIG. 3  are numbered using the same reference numbers.  
         [0039]     The diffuser endcap  82  illustrated in  FIG. 6  provides a radial discharge of inflation fluid from the inflator  12 ′. A tubular discharge portion  210  of the diffuser endcap  82  extends axially away from an annular wall portion  100  of the diffuser endcap. The tubular discharge portion  210  includes cylindrical inner and outer surfaces  212  and  214 , respectively. The inner surface  212  of the tubular discharge portion  210  extends from the cylindrical end surface  106  of the annular wall portion  100 . The outer surface  214  of the tubular discharge portion  210  joins with and extends perpendicular to the outer surface  104  of the annular wall portion  100 . A radially extending wall  216  closes an end of the tubular discharge portion  210  opposite the annular wall portion  100 . The radially extending wall  216  includes inner and outer surfaces  218  and  220 , respectively. The inner surface  212  of the tubular discharge portion  210  and the inner surface  218  of the radially extending wall  216  collectively form a discharge chamber  222 . Passage  116  leads from the chamber  130  into the discharge chamber  222 .  
         [0040]     A plurality of flow openings  224  extends radially through the tubular discharge portion  210 .  FIG. 6  illustrates two flow openings  224 . The flow openings  224  provide for radial flow of inflation fluid out of the inflator  12 ′. The inflator  12 ′ of  FIG. 6  operates in substantially the same manner as the inflator  12  of  FIG. 3  for providing inflation fluid to an inflatable vehicle occupant protection device. The fill valve assembly  140  of  FIG. 6  is identical to the fill valve assembly  140  described above with reference to  FIGS. 2-5 .  
         [0041]     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. For example, the passage  92  for receiving the fill valve assembly  140  may be located on the body portion  40  of the inflator  12 ,  12 ′ or on the annular wall portion  100  of the diffuser endcap  82 . Also, the inflator  12  may store a non-combustible gas under pressure. The inflator  12  may be connected to the inflatable vehicle occupant protection system in any manner, which may include eliminating the fill tube  34  of  FIG. 1 . Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.
An inflator ( 12) includes structure ( 40, 50, 82) defining a chamber ( 130). First and second passages ( 92 and 116) extend through the structure ( 40, 50, 82). A burst disk ( 120) closes the first passage ( 116). A valve housing ( 142) is received in the second passage ( 92) and defines a fill passage ( 154). A fluid ( 186) is stored under pressure in the chamber ( 130). An igniter ( 70) is actuatable for opening the burst disk ( 120) for enabling the fluid ( 186) to flow out of the chamber ( 130) through the first passage ( 116). A valve member ( 144) enables flow of the fluid ( 186) through the fill passage ( 154) of the valve housing ( 142) into the chamber ( 130) and prevents flow out of the chamber ( 130) through the fill passage ( 154).