Patent Publication Number: US-2006017266-A1

Title: Passenger protecting device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      The present application is a Continuation in Part of U.S. patent application Ser. No. 10/882,181 filed on Jul. 2, 2004. 
    
    
     BACKGROUND  
      The present invention relates to a passenger protecting device for protecting a passenger in a seat in a vehicle, such as an automobile, in the event of a collision, and particularly relates to a passenger protecting device having a configuration for restraining the waist of the passenger in a frontal collision so as to prevent forward and backward movement of the body of the passenger.  
      Japanese Unexamined Patent Application Publication No. 10-217818 discloses a system for protecting a passenger in an automobile in a collision. More specifically, Japanese Unexamined Patent Application Publication No. 10-217818 discloses a passenger protecting device for preventing the submarine phenomenon, which is a phenomenon wherein the passenger who wears a seat belt passes under a lap belt in a frontal collision, wherein an inflatable bag is disposed between a seat cushion and a seat pan, and is inflated so as to push up the front portion of the seat cushion in a collision of the vehicle.  
       FIG. 15  is a longitudinal cross-sectional view which shows a passenger protecting device along the longitudinal direction of a seat. An airbag  204  is disposed between a cushion frame (seat pan)  200  and a seat pad (seat cushion)  202  at the front portion of the seat. The airbag  204  extends in the width direction of the seat, and can be inflated by actions of an inflator (gas bag)  206 . The upper face of the seat pad  202  is covered with a trim cover  208 , on which the passenger sits.  
      In the event that the inflator  206  operates in a collision of the vehicle, the airbag  204  is inflated so as to push up the front portion of the seat pad  202 , or so as to reduce the flexibility thereof due to the pressure of the airbag  204  underneath the seat pad  202 , thereby preventing forward movement of the body of the passenger, as well as restraining the passenger.  
      The passenger protecting device disclosed in Japanese Unexamined Patent Application Publication No. 10-217818 has a problem in that the airbag  204  disposed underneath the seat pad  202  may be damaged due to friction between the airbag  204  and the seat pad  202 .  
      Furthermore, with the passenger protecting device disclosed in Japanese Unexamined Patent Application Publication No. 10-217818, the airbag  204  tends to inflate with maximum inflation around the middle portion thereof in the longitudinal direction, in the shape of a spindle. With such inflation of the airbag  204  in the shape of a spindle, the seat pad  202  is pushed up by a strong force around the middle portion in the lateral direction thereof, but is not pushed up by strong force around portions on both the left and right sides thereof where the left and right thighs of the passenger are to be positioned, as compared with the middle portion. Accordingly, there is the need to employ an airbag with a great capacity as the airbag  204 , sufficient for pushing up the left and right portions of the seat pad  202  by a strong force. In addition, there is the need to employ an inflator with a high performance as the inflator  206 , corresponding to the airbag  204  with a great capacity.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a passenger protecting device for reducing the damage to an airbag disposed underneath a cushion due to friction between the airbag and the cushion, or the like.  
      Furthermore, it is an object thereof to provide a passenger protecting device wherein the entire airbag including the left and right portions thereof is rapidly inflated so as to push up the lower face of the entire seat cushion, including the left and right portions thereof, without a gas generator with a high performance.  
      According to an embodiment of the present invention, a passenger protecting device for protecting a passenger of a vehicle in a case of an emergency includes: an inflatable bag disposed underneath a front portion of a seat cushion, for pushing up a lower face of the front portion of said seat cushion, a gas generator for inflating said bag in the case of emergency of the vehicle, and a cover for covering said bag, wherein the cover opens or expands due to pressure of said bag at a time of inflation of said bag.  
      It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and other features, aspects, and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below.  
       FIG. 1  is a perspective view which shows a seat frame including a passenger protecting device according to an embodiment of the present invention.  
       FIG. 2  is a cross-sectional view taken along line II-II in  FIG. 1 .  
       FIG. 3  is a disassembled perspective view which shows a passenger protecting device according to another embodiment of the present invention.  
       FIG. 4  is a longitudinal cross-sectional view which shows the passenger protecting device shown in  FIG. 3 .  
       FIG. 5  is a cross-sectional view taken along line V-V in  FIG. 4 .  
       FIG. 6   a  is a perspective view which shows another configuration for sealing both ends of the envelope cloth.  
       FIG. 6   b  is a cross-sectional view taken along line B-B in  FIG. 6   a.    
       FIG. 7  is a disassembled perspective view which shows a combination of a bag with a bag envelope and an envelope cloth.  
       FIG. 8  is a perspective view which shows an arrangement example of an envelope cloth including tear lines.  
       FIG. 9  is a perspective view which shows another arrangement example of an envelope cloth including tear lines.  
       FIG. 10  is a perspective view which shows an arrangement example of an envelope cloth including an opening for releasing the inflated bag.  
       FIG. 11   a  is an explanatory diagram for describing another arrangement example of an envelope cloth.  
       FIG. 11   b  shows an arrangement of the envelope cloth in which wrapping of the sheet member is completed.  
       FIG. 12  is a disassembled perspective view which shows a passenger protecting device according to another embodiment of the present invention.  
       FIG. 13   a  is an explanatory diagram which shows another configuration example of a patching plate.  
       FIG. 13   b  is a perspective view which shows the patching plate mounted on a side-wall supporting member.  
       FIG. 13   c  is a cross-sectional view taken along line C-C in  FIG. 13   b.    
       FIG. 14   a  is a perspective view which shows a patching plate according to another embodiment.  
       FIG. 14   b  is a cross-sectional view which shows the patching plate mounted to a side-wall supporting member taken along line B-B in  FIG. 14   a.    
       FIG. 15  is a cross-sectional view which shows a conventional passenger protecting device.  
       FIG. 16  is a disassembled perspective view of a passenger protecting device according to another embodiment of the present invention.  
       FIG. 17  is a disassembled view illustrating the configuration of attaching the passenger protecting device shown in  FIG. 16  to the seat pan.  
       FIG. 18  is a longitudinal-section view of a seat having the passenger protecting device shown in  FIG. 16 .  
       FIG. 19  is a plan view of a cover of the passenger protecting device shown in  FIG. 16 .  
       FIG. 20  is a longitudinal-section view of the passenger protecting device shown in  FIG. 16  with the bag inflated.  
       FIG. 21   a  is a plan view of a cover according to an embodiment of the present invention.  
       FIG. 21   b  is a cross-sectional diagram of the cover along line B-B in  FIG. 21   a.    
       FIG. 22   a  is a plan view of a cover according to an embodiment of the present invention.  
       FIG. 22   b  is a cross-sectional diagram of the cover along line B-B in  FIG. 22   a.    
       FIG. 23   a  is a plan view of a cover according to an embodiment of the present invention.  
       FIG. 23   b  is a cross-sectional diagram of the cover along line B-B in  FIG. 23   a.    
       FIG. 24   a  is a cross-sectional view of a cover according to another embodiment, wherein the bag is not inflated.  
       FIG. 24   b  is a cross-sectional view illustrating a state wherein the bag is inflated.  
       FIG. 25  is a longitudinal-section view of a passenger protecting device according to another embodiment of the present invention.  
       FIG. 26  is a longitudinal-section view of a passenger protecting device according to another embodiment of the present invention.  
       FIG. 27   a  is a perspective view of a passenger protecting device according to another embodiment.  
       FIG. 27   b  is a cross-sectional view along line B-B in  FIG. 27   a.    
       FIG. 27   c  is a cross-sectional view along the same portion as in  FIG. 27   b  in the state wherein the bag has inflated. 
    
    
     DETAILED DESCRIPTION  
      Embodiments of the present invention will be described below with reference to the drawings.  
       FIG. 1  is a perspective view which shows a seat frame of a seat including a passenger protecting device according to an embodiment of the present invention, and  FIG. 2  is a cross-sectional view taken along line II-II in  FIG. 1 .  FIG. 1  shows the frame forming the seat of an automobile, with the frame including a base frame  1  and a back frame  4  rotatably mounted to the base frame  1  through a support shaft  2  and a reclining device (not shown). Furthermore, the back frame  4  includes a headrest  6  on the upper portion thereof. The base frame  1  includes left and right side frames  1   a  and  1   b,  wherein a seat pan  8  is disposed between the front portions of the side frames  1   a  and  1   b.    
      Furthermore, a seat cushion (not shown) and a seat bag formed of urethane or the like (not shown) are mounted on the base frame  1  and the back frame  4 . The seat pan  8  is disposed underneath the front portion of the seat cushion. Reference numeral  1   d  in  FIG. 1  denotes springs for supporting the seat cushion.  
      A passenger protecting device  10  comprises an inflatable bag  12  for pushing up the lower face of the front portion of the seat cushion, a gas generator  14  for inflating the bag  12 , a bag envelope  16  for surrounding the bag  12 , a cover  18  for covering the bag  12 , the gas generator  14 , and the bag envelope  16 , which are disposed on the upper face of the seat pan  8 .  
      With such a configuration, the seat pan  8  may include a recess  20  on the upper face thereof, extending in the width direction of the seat (in the left and right direction thereof), so that the bag  12  may be folded and stored in the recess  20  along with the bag envelope  16  in normal situations (except for emergency situations such as a collision of the vehicle or the like). Note that the bag  12  may be disposed within the recess  20  so as to extend along the width direction thereof.  
      The bag envelope  16  may be formed in the shape of a tube for surrounding the outer face of the bag  12 . The bag envelope  16  may be formed with a smaller surrounding length than with the bag  12  at the time of free inflation thereof.  
      Note that the bag envelope  16  may be formed with generally the same length in the width direction thereof (in the longitudinal direction of the bag  12 ) as with the bag  12 , or may be formed with a smaller length thereof. Specifically, the bag envelope  16  is preferably formed with a length in the width direction of 40% to 100% of the length of the bag  12  in the width direction, more preferably with a length in the width direction of 50% to 90% thereof. The bag envelope  16  may be formed of a single envelope, or may be formed of multiple envelopes so as to surround multiple portions along the longitudinal direction. The bag envelope  16  formed of multiple envelopes is preferably formed with the sum of lengths of all the envelopes in the width direction within the aforementioned range.  
      The bag envelope  16  is preferably formed of a material or with a configuration wherein the bag envelope  16  does not readily stretch, or does not stretch at all, in the circumferential direction thereof. Furthermore, the bag envelope  16  preferably has a moisture-proof (waterproof) configuration. The bag envelope  16  may be formed of a relatively flexible material such as cloth, a synthetic resin sheet, a synthetic resin mesh sheet, or the like, or may be formed of a rigid material such as a metal sheet, metal mesh, or the like.  
      Furthermore, the passenger protecting device  10  according to the present embodiment may have a configuration wherein the cylindrical gas generator  14  is disposed within the bag  12 . The gas generator  14  may be disposed such that the longitudinal direction thereof matches the width direction of the vehicle. The gas generator  14  may include gas nozzles (not shown) on the circumferential face thereof for discharging gas radially in all directions.  
      The gas generator  14  may include a stud bolt  14   a  protruding therefrom. Specifically, the stud bolt  14   a  may pass through the lower faces of the bag  12  and the bag envelope  16 , and the bottom of the recess  20 , and protrude downward from the seat pan  8 . The stud bolt  14   a  may be secured to the seat pan  8  with a nut  14   b.  Thus, the gas generator  14 , the bag  12 , and the bag envelope  16 , are secured to the seat pan  8 .  
      Note that the passenger protecting device  10  according to the present embodiment may have a configuration wherein multiple stud bolts  14   a  are provided to the gas generator  14  in the longitudinal direction thereof at predetermined intervals for securing the gas generator  14 , the bag  12 , and the bag envelope  16 , to the seat pan  8 .  
      Furthermore, the cover  18  may be mounted for covering the bag  12 , the bag envelope  16 , and the gas generator  14  that are disposed within the recess  20 . The cover  18  may be formed in the shape of a plate with a size sufficient for covering the entire area of the recess  20 , and may be secured to the seat pan  8  through a pair of the flanges facing upward on the front and rear sides of the vehicle by bolts  22  and nuts  24 .  
      The cover  18  may have a configuration wherein upon inflation of the bag  12 , one of three actions is performed, i.e., (1) the cover  18  deforms so as to inflate upward following inflation of the bag  12 , (2) the cover  18  tears due to the pressure from inflation of the bag  12  so as to allow further inflation of the bag  12 , (3) the bolts  22  separate from the cover  18  due to inflation of the bag  12  so that the cover  18  is pushed up.  
      With the passenger protecting device  10  having such a configuration, upon detection of a frontal collision of the automobile, the gas generator  14  operates so as to discharge gas, and accordingly, the bag  12  inflates upward due to gas discharged from the gas generator  14  so as to push up or push away the cover  18 . As a result, the front portion of the seat cushion is pushed up, or is pressed upward so as to reduce the flexibility thereof, thereby preventing or suppressing forward movement of the waist of the passenger.  
      With such a configuration, the bag envelope  16  may be secured to the seat pan  8 , and accordingly, the inflated bag  12  is restrained by the seat pan  8  through the bag envelope  16 . This action prevents or suppresses the forward movement of the bag  12  at the time when the inflated bag  12  is affected by the forward pressing force from the waist of the passenger moving in the forward direction of the vehicle, thereby reducing forward movement of the body of the passenger.  
      Note that with such a configuration, the bag envelope  16  may encompass the entire bag  12  including portions around both left and right ends thereof, and accordingly, the bag  12  inflates with generally the same inflation (the same inflation width or inflation cross-sectional area) over the entire range including portions around both left and right ends. Thus, the lower face of the seat cushion is pushed up with generally the same pressing force over the entire range including the left and right sides thereof.  
      Furthermore, the bag envelope  16  may be formed with a smaller surrounding length than with the bag  12  at the time of free inflation thereof, and accordingly, with such a configuration according to the present embodiment wherein the bag  12  is inflated while being encompassed by the bag envelope  16 , the maximum size (maximum diameter) thereof is suppressed to the size corresponding to the surrounding length of the bag envelope  16 , thereby increasing the pressure of the bag  12 . Thus, the bag  12  is rapidly inflated over the entire range.  
      The passenger protecting device  10  may have a configuration wherein the bag  12 , the bag envelope  16 , and the gas generator  14 , are mounted within the recess  20  formed on the upper face of the seat pan  8 , and are covered with the cover  18 , thereby reducing damage thereof due to friction between these components and the seat cushion, or the like, during normal operation. Furthermore, the cover  18  reduces lumpiness of the seat cushion due to the bag  12 , the bag envelope  16 , the gas generator  14 , the recess  20 , and the like, thereby providing a comfortable seat cushion.  
      Thus, the bag may be formed with reduced durability, thereby reducing costs of the bag having such a configuration. Note that the cover opens or expands due to the pressure of the bag at the time of inflation of the bag. The cover may be formed of an elastic material or a plastic material, thereby allowed increased expansion of the cover during inflation of the bag.  
      Furthermore, with the passenger protecting device according to the present embodiment, the bag envelope may be included so as to cover at least a part of the bag along the longitudinal direction thereof, thereby preventing the middle portion of the bag along the longitudinal direction thereof from excessively expanding as compared with both ends thereof at the time of inflation of the bag, thereby aiding sufficient inflation of both left and right ends of the bag. As a result, both left and right portions of the seat cushion are pushed up from the bag disposed underneath the seat cushion. Furthermore, both left and right sides of the bag can be inflated without using a high-performance gas generator, thereby reducing costs and weight of the gas generator.  
      Furthermore, the bag envelope may be formed so as to surround a middle portion of the bag along the longitudinal direction thereof, or may be formed so as to surround multiple parts along the longitudinal direction thereof. With such a configuration, wherein the bag envelope is formed so as to cover a part of the bag along the longitudinal direction thereof, the bag envelope can be formed of a small amount of material.  
      The passenger protecting device according to the present invention may have a configuration wherein the bag envelope is formed so as to surround the bag over the entire range from a portion around the left end up to a portion around the right end. With such a configuration, the bag can be inflated with generally the same magnitude (e.g., inflation width, or inflation cross-sectional area) over the range from a portion around the left end up to a portion around the right end. Thus, the lower face of the seat cushion may be pushed up with generally the same pushing force over the range from the left portion up to the right portion.  
      With the passenger protecting device according to the present invention, the bag envelope may be formed with a smaller surrounding length for surrounding the bag than with the inflated bag. With such a configuration, the maximum surrounding length of the bag may be suppressed to the surrounding length of the bag envelope at the time of inflation of the bag, thereby increasing the pressure of the bag. Furthermore, this action effects sufficiently rapid inflation of the bag over the entire range thereof.  
      The passenger protecting device according to the present invention may have a configuration wherein the bag envelope is connected to the seat pan. With such a configuration, the inflated bag may be restrained by the seat pan through the bag envelope. Thus, even in the event that pressing force is applied to the inflating bag in the forward direction from the waist of the passenger moving in the forward direction, forward movement of the bag is prevented or suppressed, thereby further reducing front movement of the body of the passenger.  
      The passenger protecting device according to the present invention may have a configuration wherein the gas generator disposed within the bag is fixed to the seat pan with a fixing member passing through the bag, and the bag is supported between the gas generator and the seat pan. With such a configuration, the bag is mounted onto the seat pan with an improved mounting strength. Furthermore, the tension applied to the fixing portion on the bag for fixing to the seat pan is reduced at the time of inflation of the bag.  
      The cover may be preferably disposed so as to block the opening at least partially. Thus, the seat cushion can be prevented from falling into the opening when the passenger sits in the seat, and comfort is maintained.  
       FIG. 3  is a disassembled perspective view which shows a passenger protecting device according to another embodiment of the present invention,  FIG. 4  is a longitudinal cross-sectional view of the passenger protecting device, and  FIG. 5  is a cross-sectional view taken along line V-V in  FIG. 4 . A passenger protecting device  10 A according to the present embodiment may include a box-shaped retainer  30  without a lid disposed on the seat pan  8 A, a bag  12 A folded and disposed within the retainer  30 , a gas generator  14 A for inflating the bag  12 A, a fixing member  32  for connecting and fixing the bag  12 A and the gas generator  14 A to the retainer  30  with stud bolts  58  described later, an envelope cloth  34  for wrapping the folded bag  12 A so as to restrain the folded bag  12 A, and a cover  18 A mounted on the retainer  30  so as to cover an opening  30   a  on the upper face of the retainer  30 .  
      The seat pan  8 A may include a bottom  8   a  disposed along the lower face of the seat cushion (not shown), and a pair of side walls  8   b  and  8   b  erected from the left and right perimeters of the bottom  8   a.  The side walls  8   b  include flange portions  8   c  on the upper ends thereof, protruding in the horizontal direction. The bottom  8   a  is formed in the form of a curve over the region from the middle portion to the rear portion thereof in the moving direction of the vehicle. That is to say, the bottom  8   a  may include a recess  20 A on the upper face thereof for mounting the retainer  30 . Note that the front perimeter of the recess  20 A may extend so as to form a slanted face  8   d  with a uphill inclination toward the forward direction.  
      The retainer  30  may be formed in the shape of a box without a lid having an opened upper face, and specifically, generally in the shape of a rectangular parallelepiped with a greater length in the width direction. The bag  12 A is disposed within the retainer  30  so as to extend along the width direction. The front and rear perimeters along the opening  30   a  formed on the upper face of the retainer  30  may protrude so as to form a front supporting member  36 F and a rear supporting member  36 B for supporting the retainer  30  by being secured to the bottom  8   a  of the seat pan  8 A. Furthermore, the left and right perimeters along the opening  30   a  thereof protrude so as to form side-wall supporting members  38  and  38  for supporting the retainer  30  by being secured to the left and right side walls  8   b  and  8   b  of the seat pan  8 A.  
      The front supporting member  36 F may extend from the front edge along the opening  30   a  formed on the upper face of the retainer  30  forward with a predetermined uphill inclination along the slanted face  8   b  formed of the front perimeter of the recess  20 A, and the tip thereof may be fixed to the bottom  8   a  of the seat pan  8  around the peak of the slanted face  8   d  with bolts  40  and nuts  42 . Note that reference numeral  44  in  FIG. 3  denotes a bolt inserting hole provided on the tip of the front supporting member  36 F, and reference numeral  46  denotes a bolt inserting hole formed on the bottom  8   a  corresponding to the bolt inserting hole  44 .  
      The rear supporting member  36 B extends backward from the rear edge of the opening  30   a  formed on the upper face of the retainer  30  with a downhill inclination, and the tip thereof is secured to the bottom  8   a  of the seat pan  8  on the rear edge of the recess  20 A with the bolts  40  and the nuts  42 . Note that reference numeral  48  in  FIG. 3  denotes a bolt inserting hole provided on the tip of the rear supporting member  36 B, and reference numeral  50  denotes a bolt inserting hole formed on the bottom  8   a  corresponding to the bolt inserting hole  48 .  
      The side-wall supporting members  38  may extend upward from the left and right edges of the opening  30   a  formed on the upper face of the retainer  30  along the side walls  8   b  of the seat pan  8 A. The tips of the side-wall supporting members  38  may protrude in the horizontal direction so as to form flange portions  38   a  which are disposed on the flange portions  8   c  formed on the upper ends of the side walls  8   b  and secured thereto with bolts (not shown).  
      Also, note that both the left and right end sides of the retainer may be directly fixed to the left and right frame portions by fastening devices such as bolts or the like or by welding or the like, or may be fixed through linking members such as brackets or the like. Also, a retainer supporting member may be provided so as to bridge between the left and fight frame portions, with the retainer provided on this supporting member.  
      The retainer may be fixed, not only to the left and right frame portions of the seat, but also to other portions (e.g., the seat pan, etc.) as well.  
      The envelope cloth  34  may be formed in the shape of a tube with openings on both ends for mounting the bag  12 A therewithin. Note that the envelope cloth  34  may have a configuration wherein upon inflation of the bag  12 A, the cloth  34  tears or expands following inflation of the bag  12 A so as to allow further inflation of the bag  12 A.  
      With such a configuration, the left and right ends of the bag  12 A and the envelope cloth  34  are connected to the side-wall supporting members  38  of the retainer  30 . As shown in  FIG. 5 , the bag  12 A may include connection members  52  on both left and right ends thereof for connecting the bag  12 A to the side-wall supporting members  38 . As shown in the drawing, each connecting member  52  includes a bolt inserting hole (reference numeral is omitted).  
      With such a configuration, the envelope cloth  34  may be formed with a greater length between both ends in the longitudinal direction than the distance between the connecting members  52  and  52  disposed on both ends of the bag  12 A. As shown in  FIG. 5 , each of both ends of the envelope cloth  34  match the corresponding end of the bag  12 A, and are folded back onto the reverse face (facing the side-wall supporting member  38 ) of the corresponding connecting member  52 . As shown in the drawing, the envelope cloth  34  includes bolt inserting holes (reference numeral is omitted) at positions corresponding to the bolt inserting holes of the connecting members  52  such that each bolt inserting hole formed on the envelope cloth  34  matches the corresponding bolt inserting hole formed on the connecting member  52  at the time of folding back both ends of the envelope cloth  34  to the reverse faces of the connecting members  52 .  
      Furthermore, a patching plate  54  may be disposed on the front face of each connecting member  52  (which is opposite to the face onto which the end of the envelope cloth  34  is folded back) with the envelope cloth  34  introduced therebetween. Each patching plate  54  includes a bolt inserting hole  54   a  ( FIG. 3 ) at a position corresponding to the bolt inserting hole formed on the connecting member  52 . With such a configuration, the patching plate  54  is formed in the shape of a “U” so as to surround the front face and both left and right sides of the side-wall supporting member  38 .  
      Note that each side-wall supporting member  38  may include a bolt inserting hole  38   b  ( FIG. 3 ) at a position corresponding to the bolt inserting hole of the connecting member  52 .  
      A bolt  56   a  is inserted into each combination formed of the bolt inserting holes of the patching plate  54 , the envelope cloth  34 , the connecting member  52 , and the side-wall supporting member  38 , and is screwed to a nut  56   b  ( FIG. 5 ), whereby both ends of the bag  12 A and the envelope cloth  34  are connected to the side-wall supporting members  38 . Note that while description has been made regarding an arrangement wherein each nuts  56   b  is secured to the reverse face of the side-wall supporting member  38  by welding or the like as shown in  FIG. 5 , an arrangement according to the present invention is not restricted to the aforementioned arrangement.  
      Both ends of the envelope cloth  34  may be folded down in two and supported and pressed between the patching plates  54  and the side-wall supporting members  38  by the aforementioned bolting. Thus, both ends of the envelope cloth  34  are sealed.  
      With such a configuration, the bag  12 A includes the rod-shaped gas generator  14 A therewithin, connected to the fixing member  32 . The fixing member  32  may be formed in the shape of a plate, is disposed so as to extend along the bottom of the retainer  30 , and may be disposed on the inner face of the lower portion of the bag  12 A so as to press the lower portion of the bag  12 A to the bottom of the retainer  30 . A stud bolt  58  protrudes from the lower face of the fixing member  32 . As shown in  FIG. 4 , the stud bolt  58  is inserted into bolt inserting holes (reference numerals are omitted) formed on the lower portions of the bag  12 A and the envelope cloth  34 , and on the bottom of the retainer  30 , so as to protrude from the lower face of the retainer  30 . A nut  60  is screwed to the stud bolt  58 , whereby the lower portions of the bag  12 A and the envelope cloth  34  are supported and pressed between the fixing member  32  and the bottom of the retainer  30 , as well as fixing the fixing member  32  to the retainer  30 .  
      The gas generator  14 A may be disposed on the upper face of the fixing member  32  such that the longitudinal direction thereof matches the width direction, and is fixed to the fixing member  32  with a bracket  62 . With such a configuration, the bracket  62  is disposed so as to protrude from the rear edge of the fixing member  32 , and is formed of a C-shaped band portion  62   a  formed in the shape of a “C” protruding from the upper faces of the fixing member  32 , and a flange portion  62   b  extending from the tip of the C-shaped band portion  62   a  along the upper faces of the fixing member  32 . The aforementioned stud bolt  58  is inserted so as to protrude downward from the flange portion  62   b,  and passes through the fixing member  32  so as to protrude downward from the fixing member  32 . The gas generator  14 A may be inserted into a space surrounded by the C-shaped band portion  62   a,  following which the nut  60  is screwed to the stud bolt  58 , whereby the flange portion  62   b  is pressed and fixed to the fixing member  32 , thereby fixing the gas generator  14 A to the fixing member  32 .  
      The cover  18 A may be formed generally in the shape of a rectangle with an area generally sufficient for covering the entire opening  30   a  formed on the upper face of the retainer  30 . The cover  18 A may be disposed such that the front edge thereof matches the upper face of the front supporting member  36 F, and the rear edge thereof matches the upper face of the rear supporting member  36 B. As shown in  FIG. 4 , the rear edge of the cover  18 A is fixed to the rear supporting member  36 B with bolts  64  and nuts  66 . In  FIG. 3 , reference numeral  68  denotes a hole formed on the rear end of the cover  18 A for inserting the bolt  64 , and reference numeral  70  denotes a bolt inserting hole formed on the rear supporting member  36 B corresponding to the bolt inserting hole  68 .  
      As shown in  FIG. 4 , the cover  18 A may include snap pins  72  on the lower face of the front edge thereof, protruding therefrom. The snap pins  72  are elastically engaged to the pin engaging openings  74  formed on the front supporting member  36 F, whereby the front edge of the cover  18 A is secured to the front supporting member  36 F. Upon inflation of the bag  12 A, the snap pins  72  are disengaged from the pin engaging openings  74 , and the cover  18 A is opened upward in the shape of a flap with the rear edge thereof as a fulcrum.  
      With the passenger protecting device  10 A having such a configuration, upon detection of a frontal collision of the automobile, the gas generator  14 A operates so as to discharge gas, thereby inflating the bag  12 A due to gas discharged from the gas generator  14 A. In this case, the envelope cloth  34  is pressed in the expanding direction by actions of the bag  12 A, and tears or expands following inflation thereof so as to allow further inflation of the bag  12 A. The inflating airbag  12 A further inflates upward while pressing and opening the cover  18 A so as to push up the front portion of the seat cushion, or so as to reduce the flexibility thereof due to pressure of the bag  12 A disposed underneath the front portion of the seat cushion, thereby preventing or suppressing front movement of the waist of the passenger.  
      With the configuration according to the present embodiment, the front supporting member  36 F may be disposed so as to extend forward from the front edge of the opening  30   a  formed on the upper face of the retainer  30  with a uphill inclination along the slanted face  8   d  formed on the front edge of the recess  20 A of the seat pan  8 A, extending forward with a uphill inclination. Upon inflation of the bag  12 A, the bag  12 A inflating forward comes into contact with the front supporting member  36 F. Thus, even in the event that extremely strong pressing force is applied to the inflating bag  12 A in the forward direction from the waist of the passenger, the front supporting member  36 F receives the bag  12 A, thereby preventing forward movement of the bag  12 A.  
      The passenger protecting device  10 A has a configuration wherein the bag  12 A, the gas generator  14 A, the fixing member  32 , the envelope cloth  34 , and the like, disposed within the retainer  30  are covered with the cover  18 A, thereby reducing damage thereof due to friction between the seat cushion and these components. Furthermore, this configuration reduces with lumpiness of on the seat cushion due to these components, thereby providing a comfortable seat cushion.  
      Description will now be made regarding a procedure for mounting the passenger protecting device  10 A onto the seat pan  8 A.  
      First, the gas generator  14 A is inserted into a space surrounded by the C-shaped band portion  62   a  of the fixing member  32 , and the stud bolt  58  is inserted into the bolt inserting hole formed on the lower portion of the bag  12 A so as to protrude outward therefrom, as well as disposing the fixing member  32  within the bag  12 A. Subsequently, the bag  12 A is folded into a long and slender form, following which the envelope cloth  34  is mounted onto the folded body formed of the bag  12 A. The stud bolt  58  is inserted into the bolt inserting hole formed on the lower portion of the envelope cloth  34 , as well, so as to protrude therefrom.  
      Next, the folded body formed of the bag  12 A surrounded by the envelope cloth  34  is disposed within the retainer  30 . In this case, the stud bolt  58  protruding from the lower portion of the envelope cloth  34  is inserted into the bolt inserting hole formed on the bottom of the retainer  30 . Subsequently, the nut  60  is screwed to the stud bolt  58  from the lower side of the retainer  30 , whereby the fixing member  32  is fixed to the retainer  30 . Furthermore, both ends of the envelope cloth  34  are folded back onto the reverse face of the connecting members  52  disposed at both ends of the bag  12 A, and the folded ends of the envelope cloth  34  and the connecting members  52  are secured to the corresponding side-wall supporting members  38  with the bolts  56   a  through the patching plates  54 .  
      Subsequently, the cover  18 A is mounted onto the retainer  30 . Subsequently, the retainer  30  is mounted onto the seat pan  8 A.  
      As described above, with the mounting sequence according to the present embodiment, the bag  12 A, the envelope cloth  34 , the gas generator  14 A, the fixing member  32 , and the cover  18 A, are mounted onto the retainer  30  beforehand, thereby efficiently performing mounting operations for mounting the passenger protecting device  10 A onto the seat pan  8 A.  
      While description has been made regarding an arrangement as shown in  FIG. 3  through  FIG. 5  wherein both ends of the envelope cloth  34  are folded back onto the reverse face of the connecting members  52 , and each end of the envelope cloth  34  folded down in two are pressed between the patching plate  54  and the side-wall supporting member  38  so as to seal each end of the envelope cloth  34 , the method for sealing both ends of the envelope cloth according to the present invention is not restricted to the aforementioned arrangement.  
       FIG. 6 ( a ) is a perspective view which shows another configuration for sealing both ends of the envelope cloth, wherein  FIG. 6 ( b ) is a cross-sectional view taken along line B-B in  FIG. 6 ( a ). In  FIG. 6 , the same reference numerals denote the same components as in  FIG. 3  through  FIG. 5 .  
      An envelope cloth  34 A shown in  FIG. 6  may be formed in the shape of a tube as with the envelope cloth  34  shown in  FIG. 3  through  FIG. 5  described above, and the bag  12 A may be inserted into either of the openings formed on both ends thereof so as to be stored therewithin. The envelope cloth  34 A may have a configuration wherein the openings of both ends thereof are closed such that the perimeter parts on each opening facing one another are in contact with each other, following which these perimeter parts may be connected to one another with connecting means such as seaming, welding, or the like, thereby sealing the envelope cloth  34 A. Note that reference numeral  34   a  in  FIG. 6 ( a ) denotes holes for inserting bolts  56   a,  formed on both ends of the envelope cloth  34 A so as to match the bolt inserting holes formed on the connecting members  52  disposed on the bag  12 A.  
      While description has been made regarding an arrangement without any bag envelope as shown in  FIG. 3  through  FIG. 5 , and  FIG. 6 , described above, an arrangement including a bag envelope may be made. In this case, as shown in  FIG. 7 , the bag envelope  16  is mounted onto the bag  12 A beforehand, following which the bag  12 A with the bag envelope  16  is disposed within the envelope cloth  34 A. Note that reference numeral  52   a  in  FIG. 7  denotes bolt inserting holes formed on the connecting members  52  disposed on both ends of the bag  12 A.  
      While description has been made regarding an arrangement as shown in  FIG. 7 , including the envelope cloth  34 A shown in  FIG. 6 , an arrangement may be made, including the envelope cloth  34  shown in  FIG. 5  through  FIG. 7 .  
      The material of the envelope cloth according to the present invention is not restricted in particular, rather, the envelope cloth may be formed of various kinds of materials such as cloth like the bag or the bag envelope, or with synthetic resin, metal, or the like, for example.  
      While description has been made regarding an arrangement with a mechanism of the envelope cloth (not shown) for allowing inflation of the bag at the time of inflation, as shown in  FIG. 3  through  FIG. 5 , and  FIG. 6 , the mechanism is not restricted in particular. For example, an arrangement may be made wherein the envelope cloth includes tear lines (lines along which the envelope cloth is to tear) formed of perforations, grooves, or the like, and upon inflation of the bag, the envelope cloth tears along the tear lines so as to allow inflation of the bag. Furthermore, an arrangement may be made wherein the envelope cloth includes an opening beforehand so as to allow inflation of the bag, and the opening is closed with a closing member in normal situations.  FIG. 8  and  FIG. 9  are perspective views which show envelope clothes  34 B and  34 C, respectively, including such tear lines, and  FIG. 10  is a perspective view which shows an envelope cloth  34 D including an opening for allowing inflation of the bag.  
      The envelope cloth  34 B shown in  FIG. 8  includes an H-shaped tear line  76  formed of a pair of side tear lines  76   a  and  76   a  on both left and right ends on the upper face thereof, extending along the circumferential direction thereof, and a center tear line  76   b,  both ends of which are connected to the middle portions of the side tear lines  76   a,  extending around the middle portion of the upper face thereof in the longitudinal direction.  
      With the envelope cloth  34 B, upon inflation of the bag (not shown) therewithin, the upper face of the envelope cloth  34 B tears in the shape of an “H” along the tear lines  76   a,    76   a,  and  76   b,  so that the upper face is opened. In  FIG. 8 , reference numerals  78   a  and  78   b  denote two flaps formed due to tearing of the upper face of the envelope cloth  34 B, which are shown by two-dot broken lines. The flaps  78   a  and  78   b  are opened upward following inflation of the bag.  
      The envelope cloth  34 C shown in  FIG. 9  includes a C-shaped tear line  80  formed of a pair of side tear lines  80   a  and  80   a  on both left and right ends on the upper face thereof, extending along the circumferential direction thereof, and a longitudinal tear line  80   b  both ends of which are connected to the rear ends of the side tear lines  80   a,  extending along the rear end of the upper face thereof in the longitudinal direction.  
      With the envelope cloth  34 C, upon inflation of the bag therewithin, the upper face of the envelope cloth  34 C tears in the shape of a “C” along the tear lines  80   a,    80   a,  and  80   b,  so that the upper face is opened. In  FIG. 9 , reference numeral  82  denotes a flap formed due to tearing of the upper face of the envelope cloth  34 C, which is shown by two-dot broken lines. The flap  82  is opened upward following inflation of the bag.  
      The envelope cloth  34 D shown in  FIG. 10  includes an opening  84  on the upper face thereof beforehand for allowing inflation of the bag at the time of inflation of the bag therewithin. The opening  84  is closed with a closing sheet  86  in normal situations.  
      With the envelope cloth  34 D having such a configuration, upon inflation of the bag therewithin, the closing sheet  86  separates from the upper face of the envelope cloth  34 D due to inflation pressure of the bag, thereby releasing the opening  84 . This mechanism allows the bag to inflate upward through the opening  84 .  
      While description has been made regarding an arrangement in the aforementioned embodiments wherein the envelope cloth is formed in the shape of a tube beforehand, the envelope cloth according to the present invention is not restricted to the aforementioned arrangements. For example, a flat sheet member may be wrapped around in the form of a tube so as to form an envelope cloth.  FIG. 11  is an explanatory diagram which shows an envelope cloth  34 E having such a configuration, wherein (a) shows a sheet member at the time of wrapping, and (b) shows the sheet member with wrapping completed.  
      The envelope cloth  34 E is formed of a sheet member  88  formed of cloth, synthetic resin, metal, or the like, and is rolled, following which a pair of edges are engaged one to another with hooks  90 , whereby wrapping thereof is completed. With the envelope cloth  34 E having such a configuration, upon inflation of the bag (not shown) therewithin, the hooks  90  are disengaged due to inflation pressure of the bag, whereby the pair of the edges of the sheet member  88  are disengaged so as to open both sides thereof.  
      Note that the present invention is not restricted to an arrangement wherein the both ends of the bag are connected to the retainer or the sheet pan.  FIG. 12  is a disassembled perspective view which shows a passenger protecting device  10 B having such a configuration. Note that in  FIG. 12 , the same components are denoted by the same reference numerals as in  FIG. 3  through  FIG. 5 .  
      The passenger protecting device  10 B may have a configuration wherein the bag does not include any connecting members on both ends thereof. Furthermore, an envelope cloth  34 F for wrapping the folded body of the bag does not include any bolt inserting holes on both ends thereof. In such a configuration, the envelope cloth  34 F may be formed in the shape of a bag for wrapping the entire folded body of the bag. The retainer  30 A for storing the bag and the envelope cloth  34 F has generally the same configuration as with the retainer  30  without side-wall supporting members  38  and  38  disposed on both left and right sides thereof shown in  FIG. 3  through  FIG. 5 .  
      The passenger protecting device  10 B may have a configuration wherein the bag and the envelope cloth  34 F are fixed within the retainer  30 A by the stud bolt  58  protruding from the lower face of the fixing member (not shown) disposed within the bag.  
      Furthermore, the configuration of the patching plate according to the present invention, used for connecting both ends of the bag to the side-wall supporting members of the retainer, is not restricted to the arrangements shown in  FIG. 3  through  FIG. 5  described above.  FIG. 13 ( a ) is a perspective view which shows a patching plate  54 A according to another embodiment,  FIG. 13 ( b ) is a perspective view which shows the patching plate  54 A mounted on the side-wall supporting member, and  FIG. 13 ( c ) is a cross-sectional view taken along line C-C in  FIG. 13 ( b ). On the other hand,  FIG. 14 ( a ) is a perspective view which shows a patching plate  54 B according to yet another embodiment,  FIG. 14 ( b ) is a cross-sectional view which shows the patching plate  54 B mounted to the side-wall supporting member taken along line B-B in  FIG. 14 ( a ), which corresponds to  FIG. 13 ( c ).  
      The patching plate  54 A shown in  FIG. 13  may be formed generally in the shape of a “U” for surrounding the side-wall supporting member  38  over the front face thereof (the face for mounting the connecting member  52  disposed at the end of the bag), one of the sides thereof, and the rear face opposite to the front face. Note that in FIGS.  13 ( b ) and ( c ), reference numeral  34 G denotes an envelope cloth for wrapping the bag and the connecting members  52  disposed on both ends thereof.  
      The patching plate  54 A may include bolt inserting holes  92   a  and  94   a  at positions on a front-face portion  92  thereof for being mounted facing the front face of the side-wall supporting member  38 , and a rear-face portion  94  for being mounted facing the rear face of the side-wall supporting member  38 , corresponding to the hole (reference numeral is omitted in  FIG. 13 ) formed on the side-wall supporting member  38  for inserting the bolt  56   a.  Furthermore, the nut  56   b  is disposed on the outer face of the rear-face portion  94  (which is opposite to the face facing the side-wall supporting member  38 ), wherein the bolt  56   a  which has passed through the bolt inserting hole  94   a  is screwed to the nut  56   b.  Note that the nut  56   b  may be secured to the rear-face portion  94  by welding or the like.  
      Both ends of the bag may be connected to the side-wall supporting members  38  using the patching plates  54 A as follows. First, each connecting member  52  disposed at the end of the bag is positioned on the front face of the side-wall supporting member  38 , following which the patching plate  54 A is mounted onto the side-wall portion  38  so as to surround the connecting member  52  and the side-wall supporting member  38  between the front-face portion  92  and the rear-face portion  94 . Subsequently, the bolt  56   a  is inserted from the front face of the side-wall supporting member  38  into the bolt inserting holes formed on the front-face portion  92 , the envelope cloth  34 G, the connecting member  52 , the side-wall supporting member  38 , and the rear-face portion  94 , following which the bolt  56   a  is screwed to the nut  56   b.  Thus, the connecting member  52  and the side-wall supporting member  38  are pressed between the front-face portion  92  and the rear-face portion  94 , thereby fixing the connecting member  52  to the side-wall supporting member  38 .  
      Note that the passenger protecting device according to the present embodiment may have the same configuration as shown in  FIG. 3  through  FIG. 5  described above, except for the above-described configuration for connecting both ends of the bag to the side-wall supporting members using the patching plates  54 A, and the same components in  FIG. 13  are denoted by the same reference numerals as in  FIG. 3  through  FIG. 5 .  
      The patching plate  54 B shown in  FIG. 14  may be formed in the shape of a “U” in the same way as with the aforementioned patching plate  54 A described above, may be formed of a front-face portion  96  for being mounted facing the front face of the side-wall supporting member  38 , and a rear-face portion  98  for being mounted facing the rear face of the side-wall supporting member  38 , and be mounted onto the side-wall supporting member  38  so as to surround the connecting member  52  of the end of the bag and the side-wall supporting member  38  between the front-face portion  96  and the rear-face portion  98 . With the present embodiment, the bag and the connecting members  52  disposed on both ends thereof are wrapped by the envelope cloth  34 G, as well.  
      The patching plate  54 B may include a bolt inserting hole  96   a  at a position on only the front-face portion  96 , corresponding to the hole (reference numeral thereof is omitted in  FIG. 14 ) formed on the side-wall supporting member  38  for inserting the bolt  56   a.  The nut  56   b  may be disposed on the rear face of the side-wall supporting member  38  (which is to be positioned between the side-wall supporting member  38  and the rear-face portion  98  of the patching plate  54 ), wherein the bolt  56   a  is screwed to the nut  56 . The nut  56   b  may be fixed to the side-wall supporting member  38  by welding or the like.  
      The patching plate  54 B according to the present embodiment may include protrusions  96   b  and  98   b  protruding from the inner faces of the front-face portion  96  and the rear-face portion  98 , respectively (these inner faces are positioned facing one to another). The protrusions  96   b  and  98   b  may protrude around the tips of the front-face portion  96  and the rear-face portion  98 , respectively, facing one to another, as shown in  FIG. 14 ( b ).  
      As shown in  FIG. 14 ( b ), the protrusion  96   b  may be formed with a height protruding from the inner face of the front-face portion  96  generally the same as the total thickness of the connecting member  52  and the envelope cloth  34 G which wraps the connecting member  52 . On the other hand, the protrusion  98   b  may be formed with a greater height protruding from the inner face of the rear-face portion  98  than the height of the nut  56   b  protruding from the rear face of the side-wall supporting member  38 . Note that the gap between the protrusions  96   b  and  98   b  formed on the tips thereof may be generally the same as the thickness of the side-wall supporting member  38 , or is somewhat smaller than the thickness thereof.  
      Both ends of the bag may be connected to the side-wall supporting members  38  using the patching plates  56 B as follows. First, each connecting member  52  disposed on the end of the bag is positioned on the front face of the side-wall supporting member  38 , following which the patching plate  54 B is mounted onto the side-wall supporting member  38  such that the connecting member  52  and the side-wall supporting member  38  are supported between the front-face portion  96  and the rear-face portion  98 . In this case, the side-wall supporting member  38  is supported between the protrusions  96   b  and  98   b  protruding from the inner faces of the front-face portion  96  and the rear-face portion  98 , respectively, whereby the patching plate  54 B is temporarily fixed to the side-wall supporting member  38 . Subsequently, the bolt  56   a  is inserted from the front face of the side-wall supporting member  38  into the bolt inserting holes formed on the front-face portion  96 , the envelope cloth  34 G, the connecting member  52 , and the side-wall supporting member  38 , following which the bolt  56   a  is screwed to the nut  56   b  disposed on the rear face of the side-wall supporting member  38 . Thus, the connecting member  52  is supported and pressed between the front-face portion  96  and the side-wall supporting member  38 , whereby the connecting member  52  is secured to the side-wall supporting member  38 .  
      The passenger protecting device according to the present embodiment may have the same configuration as in  FIG. 3  through  FIG. 5  described above, except for the above-described configuration for connecting the both ends of the bag to the side-wall supporting portions using the patching plates  54 B, and the same components shown in  FIG. 14  are denoted by the same reference numerals as in  FIG. 3  through  FIG. 5 .  
       FIG. 16  illustrates a disassembled perspective view of the passenger protecting device  10 C according to another embodiment of the present invention,  FIG. 17  is a disassembled view (longitudinal-section view) illustrating the configuration of attaching this passenger protecting device  10 C to the seat pan,  FIG. 18  is a longitudinal-section view of a seat having this passenger protecting device  10 C,  FIG. 19  is a plan view of a cover of the passenger protecting device  10 C, and  FIG. 20  is a longitudinal-section view of the passenger protecting device  10 C with the bag inflated.  
      According to an embodiment of the present invention, the passenger protecting device  10 C may include a bag  12  that is long in the horizontal direction, which may be folded up and placed on a seat pan  8 , a gas generator  14 A for inflating the bag  12 , a fixing member  32  whereby the bag  12  and the gas generator  14 A are each linked and fixed to the seat pan  8  by a stud bolt  58 , an envelope cloth  34 ′ for wrapping the folded article of the bag  12  so as to restrain the bag  12  in the folded state, a cover  100  for covering the folded article of the bag  12 , and a holding member  110  for holding the folded article of the bag  12  to the cover  100 .  
      The cover  100  may include a main plate portion  101  disposed above the folded article of the bag  12 , a surrounding frame portion  102  hanging down from the lower face of the main plate portion  101 , a tear line  103  for tearing open the main plate portion  101  at the time of the bag  12  inflating, and retaining claws  104  for the holding member  110  retaining against the surrounding frame portion  102 . In the present embodiment, the main plate portion  101  may be a generally rectangular plate shape. The surrounding frame portion  102  may be a generally rectangular cylindrical shape longer in the sideways direction, with each of the faces extending along the four sides of the main plate portion  101 . The edge portion  101   a  of the main plate portion  101  may extend further outwards than the perimeter of the surrounding frame portion  102 . Retaining claws  104  may be erected on the outer face of each wall portion at the front side and rear side of the surrounding frame portion  102 .  
      With this embodiment, as shown in  FIG. 19 , the tear line  103  may include a center tear portion which passes through the center portion of the main plate portion  101  and extends in the left and right directions, and a left tear portion and right tear portion which each connect to the left end and right end of the center tear portion. The tear line  103  may be formed of a groove provided on the lower face of the main plate portion  101 . The left tear portion and right tear portion may each extend in the front and back directions (the front and back directions of the seat) along the base edges of the left and right wall portions of the surrounding frame portion  102 . The ends of the center tear portion may merge with around the center of the left tear portion and the right tear portion, respectively. At the time of the bag  12  inflating, the main plate portion  101  tears open along the center tear portion and left tear portion and right tear portion, forming two flaps  106  and  106  ( FIG. 20 ) which open toward the front and the back, respectively.  
      The cover  100  may be formed of a synthetic resin such as polypropylene or the like, but is not restricted thereto.  
      The holding member  110  may be disposed so as to traverse the lower side of the surrounding frame portion  102  in the front-back direction. Retaining pieces  111  and  111 , which pass around from the lower side of the surrounding frame portion  102  to the outer side faces of the front and rear wall portions of the surrounding frame portion  102 , are provided on both ends of the holding member  110 . Each retaining piece  111  may have a retaining hole  112  to which a retaining claw  104  engages.  
      This holding member  110  may be formed of synthetic resin or metal for example, but is not restricted thereto.  
      With this embodiment, a recessed portion  20 ′ where the surrounding frame portion  102  intrudes may be formed on the upper face of the front portion of the seat pan  8 .  
      Other configurations of the passenger protecting device  10 C are the same as those of the above-described passenger protecting device  10 A, and the same reference numerals indicate the same portions.  
      In the case of a configuration wherein the cover comprises a main plate portion disposed above the bag, and a surrounding frame portion hanging down from the main plate portion, with the bag disposed within the surrounding frame portion, the side perimeter of the bag is surrounded with the surrounding frame portion, and the upper side is covered with the main plate portion. Accordingly, damage due to abrasion or the like of the bag can be substantially reduced. Also, the bag can be prevented from directly striking against or hanging on the seat pan or the like can be prevented at the time of mounting the integrally assembled bag and cover to the seat pan.  
      An exemplary procedure for assembling the passenger protecting device  10 C and the procedures for mounting to the seat pan  8  will be described below.  
      In this arrangement as well, first, a rod-shaped gas generator  14 A is linked to the fixing member  32  with the fixing member  32  being disposed within the bag  12 , and with a stud bold  58  for fixing the fixing member  32  externally protruding from the bag through a bolt through hole (symbol omitted). Also, a harness  14   h  for conducting electricity to the gas generator  14 A is extended out from the bag  12  through a harness extending opening (omitted from the drawings) of the bag  12 . Next the bag  12  is folded in a long and slender shape, and the folded article of the bag  12  is covered with the envelope cloth  34 ′. The stud bolt  58  also protrudes from a bolt through hole (symbol omitted) at the lower portion of the envelope cloth  34 ′.  
      Next, the folded article of the bag  12  covered by the envelope cloth  34 ′ is positioned within the surrounding frame portion  102  of the cover  100 . Next, the holder member  110  is disposed so as to traverse the lower side of the surrounding frame portion  102 , and the retaining pieces  111  on both ends thereof are retained by the retaining claws  104 . Thus, the folded article of the bag  12  is supported from the below by the holding member  110 , and is held within the surrounding frame portion  102 .  
      Next, the stud bolt  58  protruding downwards from the folded article of the bag  12  is inserted into a bolt through hole  8   f  ( FIG. 17 ) on the base of the recessed portion  20 ′, and the surrounding frame portion  102  is made to intrude into the recessed portion  20 ′. At this time, the edge portion  101   a  of the main plate portion  101  extending outwards from the perimeter of the surrounding frame portion  102  overlaps with the perimeter of the recessed portion  20 ′, so that the main plate portion  101  covers the recessed portion  20 ′.  
      Subsequently, the stud bolt  58  is fastened with a nut  60  from the lower side of the seat pan  8 , and the fixing member  32  is fixed to the base portion of the recessed portion  20 ′. Thus, the lower portions of the bag  12  and the enveloped cloth  34 ′ are pinched and fixed between the fixing member  32  and the base of the recessed portion  20 ′. Further, the perimeter portion  101   a  of the main plate portion  101  is fastened to the seat pan  8  by rivets  105  through rivet through holes  101   b  and  8   e  ( FIG. 17 ). Thus, the passenger protecting device  10 C is mounted to the seat pan  8 .  
      With the passenger protecting device  10 C, the folded article of the bag  12  can be held to the cover  100  by the holding member  110  and these attached to the seat pan  8  together, so assembly work of the passenger protecting device  10 C to the seat pan  8  is easy.  
      Also, with this arrangement, the bag  12  may be held within the surrounding frame portion  102 , so the bag  12  can be prevented from directly striking against or hanging on the seat pan  8  or the like at the time of mounting the integrally assembled bag  12  and cover  100  to the seat pan  8 .  
      In the case of a configuration wherein the holding member is disposed so as to traverse the surrounding frame portion, the bag is supported by the holding member from below, so the bag can be prevented in a sure manner from falling out of the cover at the time of mounting the integrally assembled bag and cover to the seat pan.  
      In the case of a configuration wherein the holding member is attached to the surrounding frame portion by engaging with a retaining portion provided on the surrounding frame portion, the holding member can be easily mounted to the surrounding frame portion.  
      Further, with the passenger protecting device  10 C, at time of normal use, the side perimeter of the bag  12  may be surrounded by the surrounding frame portion  102 , and the upper side is covered with the main plate portion  101 , so damage due to abrasion or the like of the bag can be reduced.  
      With this arrangement, the surrounding frame portion  102  is disposed within the recessed portion  20 ′, preventing ill comfort in sitting due to the surrounding frame portion  102 , and the bag  12  and gas generator  14 A and the like therein jutting into the seat cushion.  
      Also, with the present embodiment, the recessed portion  20 ′ may be covered by the main plate portion  101 , and further the edge portion  101   a  of the main plate portion  101  may be fixed to the perimeter of the recessed portion  20 ′ by rivets  105 , preventing water (e.g., drinking water), trash, sand, and other like foreign material from entering the recessed portion  20 ′, thereby preventing deterioration and damage of the bag  12  due to water, foreign material, and the like. Note that other fastening devices besides rivets  105 , such as bolts or the like, may be used to fix the edge portion  101   a  to the seat pan  8 .  
       FIG. 21  through  FIG. 23  are each explanatory diagrams of covers  100 A,  100 B, and  100 C, according to different embodiments each, wherein (a) is a plan view of the cover, and (b) is a cross-sectional diagram along line B-B in (a). Note that (b) illustrates the bag inflated (the state wherein the main plate portion of the cover has torn open).  
      An embodiment of the present invention is shown in the example of  FIG. 21 . With the cover  100 A in  FIG. 21 , a tear line  103 A may be provided on the lower face of the main plate portion  101 , comprising a horizontal tear portion which extends in the horizontal direction along the base edge of the wall portion at the front side of the surrounding frame portion  102 , and a left tear portion and right tear portion which each extend in the front-back direction along the base edges of the wall portions at the left and right sides of the surrounding frame portion  102 , and connect to the left end and right end of the horizontal tear portion.  
      With the cover  100 A, in the case of the bag  12  inflating, as shown in  FIG. 21 ( b ), the main plate portion  101  tears open following the horizontal tear portion at the front side and the left tear portion and right tear portion, so that the general entirety of the main plate portion  101  opens toward the back as a single flap  106 A.  
      An embodiment of the present invention is shown in the example of  FIG. 22 . With the cover  100 B in  FIG. 22 , a tear line  103 B may be provided on the lower face of the main plate portion  101 , comprising a horizontal tear portion which extends in the horizontal direction along the base edge of the wall portion at the back side of the surrounding frame portion  102 , and a left tear portion and right tear portion which each extend in the front-back direction along the base edges of the wall portions at the left and right sides of the surrounding frame portion  102 , and connect to the left end and right end of the horizontal tear portion.  
      With the cover  100 B, in the case of the bag  12  inflating, as shown in  FIG. 22 ( b ), the main plate portion  101  tears open following the horizontal tear portion at the back side and the left tear portion and right tear portion, so that the general entirety of the main plate portion  101  opens toward the front as a single flap  106 B.  
      An embodiment of the present invention is shown in the example of  FIG. 23 . With the cover  100 C in  FIG. 23 , a tear line  103 C may be provided on the lower face of the main plate portion  101 , comprising two horizontal tear portions which extend in the horizontal direction along the base edges of the wall portions at the front and back sides of the surrounding frame portion  102 , and a vertical tear portion which extends in the front-back direction so as to connect the horizontal tear portions at the middle portions thereof.  
      With the cover  100 C, in the case of the bag  12  inflating, as shown in  FIG. 23 ( b ), the main plate portion  101  tears open following the horizontal tear portions at the front and back sides and the vertical tear portion, so that the main plate portion  101  opens toward the left and right as two flaps  106 C and  106 C.  
       FIG. 24  is a cross-sectional view of a cover  100 D according to yet another embodiment, wherein (a) illustrates a state wherein the bag is not inflated, and (b) illustrates a state wherein the bag is inflated (state wherein the main plate portion of the cover is torn open).  
      With the cover  100 D, the main plate portion  101 D may be curved in a convex shape upwards so that around the center portion in the front and back direction may be the highest position. Note that in this embodiment, a tear line  103  extending in the left and right directions may be provided around the middle in the front and back direction.  
      With the cover  100 D, in the case of the bag  12  inflating, the main plate portion  101 D tears open following the tear line  103 , so that the plate portion  101  opens toward the front and back as flaps  106 D and  106 D. As shown in  FIG. 24 ( b ), the flaps  106 D and  106 D are each curved so as to contour along the outer face of the bag  12 , so a situation wherein the flaps  106 D jut into the seat cushion and excessively press the seat cushion can be prevented.  
       FIG. 25  illustrates a longitudinal-section view of a passenger protecting device  10 E according to yet another embodiment. The passenger protecting device  10 E may also include a bag  12  long in the horizontal direction, which is folded up and placed on the seat pan, a gas generator  14 A for inflating the bag  12 , a fixing member  32  whereby the bag  12  and the gas generator  14 A may be each linked and fixed to the seat pan  8  by a stud bolt  58 , and a cover  100 E for covering the folded article of the bag  12 . In this embodiment as well, the cover  100 E may include a main plate portion  101  disposed above the folded article of the bag  12 , a surrounding frame portion  102  hanging down from the lower face of the main plate portion  101 , and a tear line  103  for tearing open the main plate portion  101  at the time of the bag  12  inflating.  
      With this embodiment as well, a recessed portion  120  may be provided on the upper face of the seat pan  8  for placing the passenger protecting device, and the surrounding frame portion  102  may be disposed within the recessed portion  120 . Also, the edge portion  101   a  of the main plate portion  101  may extend to the perimeter portion of this recessed portion  120 , overlap the upper face of the seat pan  8 , and may be fastened by rivets  105 .  
      With this embodiment, a groove  121  may be formed on the perimeter portion of the base of the recessed portion  120 , with the lower end of the surrounding frame portion  102  intruding into this groove  121  over the entire circumference thereof.  
      Other configurations of the passenger protecting device  10 E are the same as those of the above-described passenger protecting device  10 C, and the same reference numerals indicate the same portions.  
      With this passenger protecting device  10 E, the groove  121  may be provided on the perimeter portion of the base of the recessed portion  120  where the surrounding frame portion  102  of the cover  100 E intrudes, and the bottom end of the surrounding frame portion  102  may be within the groove  121 , so even in the event that water does flow in along the inner wall portion of the recessed portion  120 , the water only collects in the groove  121 , so the bag  12  can be prevented from getting wet from the water.  
      Also, as with a passenger protecting device  10 E′ shown in  FIG. 26 , providing a groove  121 A on the perimeter portion of the base of the recessed portion  120 A where the surrounding frame portion  102  of the cover  100 E′ intrudes so as to be capable of tightly engaging with the bottom end of the surrounding frame portion  102 , can sufficiently prevent water from flowing into the recessed portion  121 A.  
       FIG. 27 ( a ) is a perspective view of a passenger protecting device according to another embodiment,  FIG. 27 ( b ) is a cross-sectional view along line B-B in  FIG. 27 ( a ), and  FIG. 27 ( c ) is a cross-sectional view along the same portion as in  FIG. 27 ( b ) in the state wherein the bag has inflated.  
      In the present embodiment, the base frame  1 A of the seat may have a seat pan  8 A which continuously extends in the front-back direction, from between the front portions of the left and right side frames  1   a  and  1   b,  to the back portions thereof. That is to say, with the present embodiment, the seat cushion (not shown) may be supported by a single seat pan  8 A from the front end to the rear end. A passenger protecting device  10 F may be disposed below the rear portion of this seat pan  8 A. With this embodiment, an opening  130  permitting the inflated bag  12  to pass through to the seat cushion side may be provided at the front portion of the seat pan  8 A.  
      With the present embodiment, the passenger protecting device  10 F may include a container-shaped retainer  140  which may be opened at the upper face side, an inflatable bag  12  folded and stored within the retainer  140 , an inflator (omitted from the drawings) for inflating the bag  12 , and a cover  100 F which closes off the upper face of the retainer  140 . Note that the bag  12  may be formed into a module beforehand by being held by a holding member (omitted from the drawings) to the cover  100 F.  
      The retainer  140  may extend in the left and right directions so as to traverse the opening  130  in this embodiment, and both ends thereof are linked to the left and right side frames  1   a  and  1   b  by fixing devices such as bolts and nuts or the like (omitted from the drawings). The bag  12  may extend in the left and right directions within this retainer  140 .  
      Though not shown in the drawings, the inflator may be disposed within the bag  12 , and may be fixed to the base of the retainer  140  through the lower portion of the bag  12 . The cover  100 F may be configured so as to tear open upon being pressed by the bag  12  at the time of the bag  12  inflating.  
      With this passenger protecting device  10 F, upon the bag  12  inflating, the bag  12  passes through the opening  130  while pressing the cover  100 F open and expands out above the seat pan  8 A, and presses the front portion of the seat cushion upwards.  
      With the present embodiment, the passenger protecting device  10 F may be disposed below the seat pan  8 A, so the passenger protecting device  10 F does not cause ill ease of comfort in sitting on the seat. Also, with this embodiment, the retainer  140  of the passenger protecting device  10 F may be disposed traversing the opening  130  of the seat pan  8 A, and the cover  100 F mounted to the retainer  140  closes off the opening  130  at least partially, thereby preventing the seat cushion from falling into the opening  130  upon the passenger sitting thereupon.  
      With this passenger protecting device  10 F, the retainer  140  may be fixed to the left and right side frames  1   a  and  1   b,  so even in the event that a great weight is placed on the inflated bag from the passenger, the bag  12  may be securely supported by the retainer  140 , so the passenger can be received by the inflated bag  12  in a sure manner.  
      Note that with the present embodiment, the left and right side ends of the retainer  140  may be directly fixed to the left and right side frames  1   a  and  1   b  by fixing devices such as bolts or the like or by welding or the like, but may be fixed by linking members such as brackets or the like (omitted from the drawings). Also, a retainer supporting member (omitted from the drawings) may be provided so as to bridge between the side frames  1   a  and  1   b,  with the retainer  140  mounted to this supporting member.  
      The retainer may be fixed to at least the left and right frame portions of the seat. Due to this configuration, the bag is securely supported by the retainer at the time of the inflated bag receiving the passenger.  
      Note that in this embodiment the retainer may be fixed, not only to the left and right frame portions of the seat, but also to other portions (e.g., the seat pan, etc.). Both the left and right end sides of the retainer may be directly fixed to the left and right frame portions, or may be fixed through linking members such as brackets or the like, or a retainer supporting member may be provided so as to bridge between the left and fight frame portions, with the retainer provided on this supporting member.  
      The retainer  140  may be fixed to other members (e.g., the seat pan  8 A, etc.), besides the left and right side frames  1   a  and  1   b.    
      The priority applications, Japanese Patent Application No. 2003-340822 filed on Sep. 30, 2003, Japanese Patent Application No. 2004-228241 filed on Aug. 4, 2004, and Japanese Patent Application No. 2005-138697 filed on May 11, 2005, are hereby incorporated by reference herein in their entirety.  
      Given the disclosure of the present invention, one versed in the art would appreciate that there may be other embodiments and modifications within the scope and spirit of the invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is to be defined as set forth in the following claims.