Patent Publication Number: US-2011062690-A1

Title: Occupant restraining apparatus for a motorcycle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2009-213113 filed on Sep. 15, 2009 the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an occupant restraining apparatus for a motorcycle. 
     2. Description of Background Art 
     Conventionally, various motorcycles which include an airbag and/or a seatbelt have been proposed. See, for example, Japanese Patent Laid-Open No. 2003-276668, FIGS. 1 and 5. 
     As shown in FIG. 1 of Japanese Patent Laid-Open No. 2003-276668, at a rear portion of a vehicle body (16) (the reference numeral in parentheses indicates a reference numeral described in Japanese Patent Laid-Open No. 2003-276668, this similarly applies also to the description given below) of a motorcycle, connection means (29) is provided, and the waist part of an occupant seated on a seat (12) is fixed by a seatbelt (24) of this connection means (29). Operation upon collision of the motorcycle is described below. 
     If the motorcycle collides, then since an airbag (19) provided at a front portion of the vehicle body (16) is inflated and expanded as shown in FIG. 5 of Japanese Patent Laid-Open No. 2003-276668, the impact force which acts upon the occupant can be absorbed by the airbag (19). Further, when a predetermined interval of time elapses after the airbag (19) starts the inflation and expansion, a tongue (27) is automatically disconnected from a buckle (28), the fixation of the occupant by the seatbelt (24) can be cancelled upon falling down after the collision. 
     In addition, in the motorcycle of Japanese Patent Laid-Open No. 2003-276668, although the occupant can be released from the motorcycle because the fixation of the occupant by the seatbelt (24) is cancelled upon falling down after a collision, it is more preferable if the occupant can be released more smoothly. 
     Therefore, an occupant restraining apparatus for a motorcycle which can release an occupant more smoothly is on demand. 
     SUMMARY AND OBJECTS OF THE INVENTION 
     It is a subject of the present invention to provide an occupant restraining apparatus for a motorcycle which can release an occupant smoothly from a vehicle body upon falling down. 
     According to an embodiment of the present invention, an occupant restraining apparatus for a motorcycle which includes an occupant&#39;s seat provided on a vehicle body and adapted to be seated by an occupant and a seatbelt provided on the occupant&#39;s seat and adapted to fix the occupant includes an occupant&#39;s seat having a releasing mechanism which allows release thereof from the vehicle body together with the occupant when the vehicle falls down. 
     According to an embodiment of the present invention, the occupant restraining apparatus includes an impact absorbing member built in a rear portion thereof, and the impact absorbing member expands when the occupant&#39;s seat is released from the vehicle body. 
     According to an embodiment of the present invention, the impact absorbing member is an airbag. 
     According to an embodiment of the present invention, the releasing mechanism is released from the vehicle body in response to detection of the falling down of the vehicle. The falling down detection detects at least one of an inclination angle of the vehicle body, a seat load and a step load to decide inclination of the vehicle body and a state of the occupant by means of a control section provided on the vehicle body. 
     According to an embodiment of the present invention, a tongue provided on the seatbelt is removably connected to a buckle provided on the occupant&#39;s seat and a seatbelt detection section is provided on the buckle such that, when the seatbelt detection section detects that the occupant does not wear the seatbelt as yet, the seatbelt detection section sends a signal to a warning notification section provided on the vehicle body so that the warning notification section issues a seatbelt wearing warning to the occupant. 
     According to an embodiment of the present invention, since the occupant&#39;s seat includes the releasing mechanism which allows release thereof from the vehicle body together with the occupant when the vehicle falls down, when the vehicle falls down, the occupant&#39;s seat can be released smoothly from the vehicle body. Thus, an occupant restraining apparatus that allows the occupant to be released smoothly from the vehicle body upon the falling down of the motorcycle can be provided. 
     Further, since the occupant&#39;s seat is released while the occupant remains seated thereon, when the occupant&#39;s seat lands on the ground surface, it can be expected to interpose the occupant&#39;s seat between the occupant and the ground surface. 
     According to an embodiment of the present invention, since the impact absorbing member built in the rear portion of the occupant&#39;s seat expands when the occupant&#39;s seat is released from the vehicle body, the occupant can be covered with the occupant&#39;s seat and the impact absorbing member. In other words, the impact absorbing member can be interposed between the occupant and the ground surface or the like. 
     According to an embodiment of the present invention, since the impact absorbing member is an airbag, the occupant can be covered with the occupant&#39;s seat and the airbag. In other words, the airbag can be interposed between the occupant and the ground surface or the like. 
     According to an embodiment of the present invention, since the falling down detection detects at least one of the inclination angle of the vehicle body, the seat load and the step load to decide inclination of the vehicle body and the state of the occupant by means of the control section provided on the vehicle body, the falling down detection of the vehicle can be carried out with certainty. By the carrying out of the falling down detection with certainty, when the vehicle falls down, the occupant&#39;s seat can be released from the vehicle body with certainty. 
     According to an embodiment of the present invention, when the seatbelt detection section detects that the occupant does not wear the seatbelt as yet, it sends a signal to the warning notification section provided on the vehicle body, and the warning notification section issues a seatbelt wearing warning to the occupant. Therefore, it is possible to urge the occupant to wear the seatbelt with certainty. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a left side elevational view of a motorcycle; 
         FIG. 2  is an exploded view of an occupant&#39;s seat and a vehicle body frame; 
         FIGS. 3(   a ) and  3 ( b ) are views showing a structure of a seatbelt; 
         FIGS. 4(   a ) and  4 ( b ) are views showing a structure of a step; 
         FIGS. 5(   a ) and  5 ( b ) are views illustrating operation of the step; 
         FIGS. 6(   a ) and  6 ( b ) are views showing a structure of a step load detection mechanism; 
         FIGS. 7(   a ) and  7 ( b ) are views illustrating operation after release of the occupant&#39;s seat till landing; 
         FIG. 8  is a flow chart until a seat lock is released; 
         FIG. 9  is a view showing a modified form of that of  FIG. 2 ; 
         FIGS. 10(   a ) and  10 ( b ) are views illustrating the operation of sliding expansion of an impact absorbing member; 
         FIG. 11  is a flow chart until the impact absorbing member is expanded; 
         FIG. 12  is a view showing another modified form of that of  FIG. 2 ; 
         FIGS. 13(   a ) and  13 ( b ) are views illustrating operation of rotational expansion of the impact absorbing member; 
         FIG. 14  is a view showing a further modified form of that of  FIG. 2 ; 
         FIGS. 15(   a ) and  15 ( b ) are views illustrating the operation of an airbag upon inflation expansion; 
         FIG. 16  is an exploded view of another occupant restraining apparatus and the vehicle body frame; 
         FIGS. 17(   a ) and  17 ( b ) are views showing a structure of a pawl member; 
         FIGS. 18(   a ) to  18 ( c ) are views illustrating the operation of another occupant&#39;s seat and the pawl member; 
         FIGS. 19(   a ) to  19 ( c ) are views showing a modified form of that of  FIGS. 18(   a ) to  18 ( c ); 
         FIGS. 20(   a ) to  20 ( c ) are views showing another modified form of that of  FIGS. 18(   a ) to  18 ( c ); 
         FIG. 21  is a view showing a configuration of another releasing mechanism; and 
         FIGS. 22(   a ) and  22 ( b ) are views illustrating the operation after an occupant&#39;s seat including a different releasing mechanism is released till landing. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention are described below with reference to the accompanying drawings. It is to be noted that the drawings should be viewed in the direction of reference symbols. Further, the front and rear and the left and right are defined with reference to a driver seated on a seat. 
     An embodiment 1 of the present invention is described with reference to the drawings. As shown in  FIG. 1 , a motorcycle  10  is a vehicle which includes a front fork  13  provided for steering operation on a head pipe  12  of a vehicle body frame  11 , a front wheel  14  provided for rotation at a lower end of the front fork  13 , a steering handle bar  15  provided at an upper end of the front fork  13 , a swing arm  17  provided for upward and downward rocking motion on a pivot plate  16  extending downwardly from a rear portion of the vehicle body frame  11 , a step  18  (details are hereinafter described) provided on the pivot plate  16 , a rear wheel  19  provided for rotation at a rear end of the swing arm  17 , an engine  21  disposed below the vehicle body frame  11  such that the rear wheel  19  is driven by the engine  21  through a chain  22 , a meter panel  24  provided at an upper portion of a front cowl  23  which covers the head pipe  12 , a seat rail  25  extending rearwardly from the upper side of a rear portion of the vehicle body frame  11 , and an occupant restraining apparatus  30  provided on the seat rail  25  which can be released from the vehicle body frame  11  upon falling down of the vehicle. 
     This occupant restraining apparatus  30  includes an occupant&#39;s seat  31  (details are hereinafter described) for being seated by an occupant, and a seatbelt  32  (details are hereinafter described) provided on the occupant&#39;s seat  31  for fixing an occupant. The mounting structure of the occupant&#39;s seat  31  and the vehicle body frame  11  will be described with reference to  FIG. 2 . 
     As shown in  FIG. 2 , the occupant&#39;s seat  31  includes a bottom plate  33 , a cushion  34  placed on the bottom plate  33 , and a skin  35  attached to the bottom plate  33  so as to cover the cushion  34 . Further, a seating portion  36  for being seated by an occupant and a waist receiving portion  37  with which the waist part of the occupant contacts are formed on an upper face of the occupant&#39;s seat  31 . 
     Further, a hook  38  extending forwardly is provided at a front end portion of the bottom plate  33 , and a seat load detection section  39  for detecting the load of an occupant seated on the seating portion  36  is attached to an intermediate portion of the bottom plate  33 . Further, a releasing mechanism  40  (details are hereinafter described) which allows release thereof from the right seat rail  25  together with an occupant upon falling down of the motorcycle (reference numeral  10  of  FIG. 1 ) is provided at a rear portion of the bottom plate  33 . 
     This releasing mechanism  40  is formed from a recessed portion  41  which is recessed upwardly from the bottom plate  33 , and a lock pin  42  extending downwardly from the recessed portion  41  such that a lower end thereof is disposed above the bottom plate  33  and removably attached to a seat lock section hereinafter described. 
     Meanwhile, a seat support member  47  on which the bottom plate  33  of the occupant&#39;s seat  31  is placed is provided on the right seat rail  25 . A set stay  48  into which the hook  38  of the occupant&#39;s seat  31  is inserted is provided at a front end portion of the seat support member  47 , and a female terminal  51  for fitting with a male terminal  49  extending from the seat load detection section  39  is attached to an intermediate portion of the seat support member  47 . Further, a well-known seat lock section  52  to which the lock pin  42  of the releasing mechanism  40  is removably connected is provided at a rear end portion of the seat support member  47 . 
     Meanwhile, the seat support member  47  has provided thereon a cylinder lock  54  and an actuator  55  which are connected to the seat lock section  52  through a wire  53  and a control section  56  which receives a signal of the seat load detection section  39  and issues an operation instruction to the actuator  55  through the male terminal  49  and the female terminal  51 . 
     In particular, the occupant&#39;s seat  31  and the right seat rail  25  are assembled by inserting the hook  38  into the set stay  48 , threading the male terminal  49  through an opening  57  of the seat support member  47  until it is fitted into the female terminal  51  and connecting the lock pin  42  to the seat lock section  52 . 
     When the vehicle falls down during traveling, a signal is transmitted from a bank angle detection section (details are hereinafter described) to the control section  56 , and the control section  56  issues an operation instruction to the actuator  55 . When the actuator  55  pulls the wire  53  to the front side, since the cylinder lock  54  is rotated to the front side simultaneously, the locking of the releasing mechanism  40  by the seat lock section  52  is canceled. It is to be noted that, also if the cylinder lock  54  is manually rotated while the vehicle stops, the locking of the releasing mechanism  40  by the seat lock section  52  is canceled. 
     Also, the male terminal  49  and the female terminal  51  are terminals of a structure by which the occupant&#39;s seat  31  comes off simply when it is released from the seat support member  47 . Now, a structure of the occupant&#39;s seat and the seatbelt is described. 
     Referring to  FIG. 3(   a ), the seatbelt  32  includes a takeup mechanism  58  provided in the inside of the left side of the occupant&#39;s seat  31 , a waist webbing  59  extending from the takeup mechanism  58  to the right side of the occupant&#39;s seat  31  past above the occupant&#39;s seat  31 , a tongue  61  provided at an end of the waist webbing  59 , and a buckle  62  to which the tongue  61  is removably connected and which is attached to the right side of the occupant&#39;s seat  31 . 
     A seatbelt detection section  63  of the contact type is attached to a side face of the buckle  62 . If the buckle  62  is mounted fully on the tongue  61 , then the tongue  61  pushes a detection piece of the seatbelt detection section  63 , and consequently, the connection state of the tongue  61  and the buckle  62  can be detected by the seatbelt detection section  63 . 
     It is to be noted that, if the mounting of the tongue  61  on the buckle  62  is not full, then the seatbelt detection section  63  detects the unconnected state of the tongue  61  and the buckle  62 . 
     The seatbelt detection section  63  is connected to a female terminal  65  attached to the right seat rail  25  through a male terminal  64 . The male terminal  64  is a terminal of a structure by which it can come off simply from the female terminal  65  when the occupant&#39;s seat  31  is released from the seat rails  25 ,  25  when the motorcycle  10  in  FIG. 1  falls down. 
     In addition, the female terminal  65  is connected to the control section  56 , and this control section  56  is connected to the meter panel  24 . If the seatbelt detection section  63  detects the unconnected state of the tongue  61  and the buckle  62 , then the seatbelt detection section  63  sends a signal to the control section  56 , and the control section  56  sends a signal to the meter panel  24 . Accordingly, a warning that the seatbelt is not worn is displayed on the meter panel  24 . 
     In particular, as shown in  FIG. 3(   b ), the tongue  61  provided on the seatbelt  32  is removably connected to the buckle  62  provided on the occupant&#39;s seat  31 , and the seatbelt detection section  63  of the contact type is provided on a side face  67  of the buckle  62 . When this seatbelt detection section  63  detects that the occupant does not wear the seatbelt as yet, it sends a signal to the meter panel  24  provided on the vehicle body, and the meter panel  24  displays a warning to wear the seatbelt to the occupant. 
     By the display of the warning to wear the seatbelt, it is possible to urge the occupant to wear the seatbelt with certainty. A detection piece  43  of the seatbelt detection section, and the seatbelt detection section  63  exhibits an ON state when the detection piece  43  is pushed by the tongue  61 . Now, a structure of the step is described. 
     Referring to  FIG. 4(   a ), the left foot  27  of an occupant is placed on the left step  18 . The left step  18  includes a support member  73  provided on the pivot plate  16 , a rotatable portion  72  (details are hereinafter described) attached for rotation on the support member  73 , a foot receiving portion  71  attached to the rotatable portion  72  for receiving the left foot  27  of the occupant placed thereon, a left bank angle detection member  68  extending downwardly from the foot receiving portion  71  and having a contact end  69  for contacting with the ground surface, and a stopper  74  extending from the foot receiving portion  71  so as to contact with the pivot plate  16  for stopping rotation of the left step  18 . 
     In addition, a step load detection mechanism  171  (details are hereinafter described) for detecting the step load is attached to the pivot plate  16 . 
     As shown in  FIG. 4(   b ), the rotatable portion  72  includes a connection member  76  having a fork portion  75  which sandwiches the support member  73 , extending to the left side, having the foot receiving portion  71  attached thereto and including a connecting portion  79 , a shaft  78  fitted in the connection member  76 , the support member  73  and a left bank angle detection section  77  (details are hereinafter described) attached to the pivot plate  16 , a pin  81  for connecting the shaft  78  and the connecting portion  79  to each other, and a pin  83  for connecting the shaft  78  and a connecting portion  82  of the left bank angle detection section  77 . It is to be noted that the left bank angle detection section  77  is covered with a cover  84 . 
     The left bank angle detection section  77  detects a bank angle when the motorcycle  10  in  FIG. 1  falls down to the left side until the contact end  69  of the left bank angle detection member  68  hits on the ground surface. The bank angle detected by the left bank angle detection section  77  is transmitted to the control section  56 . Now, the operation of the left step  18  is described. 
     Referring to  FIG. 5(   a ), the motorcycle  10  is driven in a state wherein it keeps a bank angle θ 1 , and the contact end  69  of the left bank angle detection member  68  contacts with the ground surface  87 . The bank angle θ 1  is an angle defined by a vehicle center line  86  of the motorcycle  10  and the ground surface  87 . 
     If the motorcycle  10  is further inclined as indicated by an arrow mark ( 1 ), then the contact end  69  of the left bank angle detection member  68  moves as indicated by an arrow mark ( 2 ) from the position of an imaginary line as shown in  FIG. 5(   b ). If the rotational angle of the left step  18  at this time is represented by θ 2 , then the rotational angle θ 2  indicates an angular variation of the left step  18  after the contact end  69  of the left bank angle detection member  68  is brought into contact with the ground surface  87 . Further, the rotational angle θ 2  is detected by the left bank angle detection section  77 . 
     In particular, in the motorcycle  10 , the rotational angle θ 2  is set, and if an angle exceeding the rotational angle θ 2  is detected by the left bank angle detection section  77 , then it is decided by the control section  56  in  FIG. 4(   b ) that the rotational angle reaches an angle at which the motorcycle  10  can fall down. Now, a structure of the step load detection mechanism  171  is described. 
     Referring to  FIG. 6(   a ), the step load detection mechanism  171  includes a case  172  attached to the pivot plate  16 , a step load detection section  173  (details are hereinafter described) attached for movement in the vehicle widthwise direction (leftward and rightward direction in the figure) to the pivot plate  16 , and a compression spring  174  provided between the step load detection section  173  and the inner face of the case  172  for exerting a pushing out action to the step load detection section  173 . 
     The step load detection section  173  includes a guide rail  175  provided on the upper side and another guide rail  176  provided on the lower side. The guide rail  175  is fitted in a guide slot  177  of the pivot plate  16 , and the guide rail  176  is fitted in a guide slot  178  of the pivot plate  16 . Consequently, the step load detection section  173  can move in the vehicle widthwise direction. 
     Since the left foot  27  of the occupant is placed on the left step  18 , a detection piece  179  of the step load detection section  173  is pushed by the stopper  74  and the step load detection section  173  compresses the compression spring  174 . The projecting length of the detection piece  179  at this time is L 1 , and the step load detection section  173  is in an ON state. Further, since the step load detection section  173  is connected to the control section  56 , an ON signal of the step load detection section  173  can be sent to the control section  56 . 
     If the left foot  27  is moved fully away from the foot receiving portion  71 , then the compression spring  174  pushes the stopper  74  leftwardly through the step load detection section  173 , the foot receiving portion  71 , left bank angle detection member  68 , connection member  76  and shaft  78  are rotated in the counterclockwise direction as illustrated in  FIG. 6(   b ). The projecting length of the detection piece  179  at this time is L 1 +α, and the step load detection section  173  is placed into an OFF state. 
     In particular, in the motorcycle  10  in  FIG. 1 , for example, when the vehicle begins to fall down, it can be detected as an OFF state of the step load detection section  173  that the left foot  27  of the occupant is spaced away from the left step  18 . Since an OFF signal of the step load detection section  173  is sent to the control section  56 , the control section  56  decides that the inclination angle of the motorcycle  10  reaches an angle at which the motorcycle  10  can fall down. 
     Operation of the occupant restraining apparatus  30  described above is described below. 
     Referring to  FIGS. 7(   a ) and  7 ( b ), when the motorcycle  10  in  FIG. 1  falls down to the left side, since the actuator  55  operates in accordance with an instruction of the control section  56  to pull the wire  53  to the front side as seen in  FIG. 7(   a ), the seat lock section  52  cancels the connection to the releasing mechanism  40 . Consequently, the occupant&#39;s seat  31  is released to the left side as indicated by an arrow mark ( 3 ) from the seat support member  47  while the occupant  85  remains seated on the occupant&#39;s seat  31 . 
     Referring to  FIG. 7(   b ), since the occupant  85  lands on the ground surface  87  while it remains seated on the occupant&#39;s seat  31 , the waist part  92  and the thigh parts  93  of the occupant  85  are covered with the occupant&#39;s seat  31 . 
     Since the occupant&#39;s seat  31  includes the releasing mechanism  40  which allows release thereof from the seat support member  47  together with the occupant  85  when the vehicle falls down, the occupant&#39;s seat  31  can be released smoothly from the seat support member  47  when the vehicles falls down. Accordingly, the occupant restraining apparatus  30  for a motorcycle which allows the occupant  85  to be released smoothly from the seat support member  47  (vehicle body) when the motorcycle falls down can be provided. 
     Further, since the occupant&#39;s seat  31  is released while the occupant  85  remains seated thereon, when the occupant&#39;s seat  31  is landed on the ground surface  87 , it can be expected to interpose the occupant&#39;s seat  31  between the occupant  85  and the ground surface  87 . Now, a flow until the seat lock is canceled when the motorcycle falls down is described. 
     As shown in  FIG. 8 , at step number (hereinafter referred to as step ST)  01 , it is confirmed whether or not the seat belt detection section is ON, and if the result of the confirmation is YES, then the processing advances to step ST 03 , but if the result of the confirmation is NO, then the processing advances to step ST 02 . In particular, it is confirmed by the seatbelt detection section  63  of the contact type whether or not the tongue  61  is fully mounted on the buckle  62  as seen in  FIG. 3(   b ). 
     At step ST 02 , an alarm is issued. In particular, a seatbelt wearing warning to the occupant is displayed on the meter panel  24  as shown in  FIG. 3(   a ). 
     It is confirmed at step ST 03  whether or not the bank angle detection section is ON, and if the confirmation is YES, then the processing advances to step ST 05 , but if the confirmation is NO, then the processing advances to step ST 04 . In particular, the rotational angle of the left step  18  is detected by the left bank angle detection section  77  as illustrated in  FIG. 5(   b ). 
     It is confirmed at step ST 04  whether or not the seat load detection section is OFF, and if the confirmation is YES, then the processing advances to step ST 05 , but if the confirmation is NO, then the processing returns to step ST 03 . At step ST 04 , the seat load detection section  39  in  FIG. 2  detects the OFF state such that it is decided by the seat load detection that the occupant has moved in a direction away from the vehicle even if it is detected that the bank angle does not reach a predetermined angle at which falling down is decided. 
     At step ST 05 , the seat lock is canceled. In particular, the seat lock section  52  cancels the connection to the releasing mechanism  40  by operation of the actuator  55  as illustrated in  FIG. 7(   a ). 
     It is to be noted that the confirmation carried out at step ST 04  regarding whether or not the seat load detection section is OFF may be replaced by a confirmation of whether or not the step load detection section  173  in  FIGS. 6(   a ) and  6 ( b ) is OFF. 
     Referring to  FIG. 7(   a ), the releasing mechanism  40  is released from the seat support member  47  in response to the falling down detection of the vehicle, and the falling down detection detects at least one of the inclination of the vehicle load, the seat load and the step load to decide the inclination of the vehicle body and the state of the occupant  85  by means of the control section  56  provided on the vehicle body. The inclination angle of the vehicle body is detected by the bank angle detection section  77  in  FIGS. 4(   a ) and  4 ( b ), and the seat load is detected by the seat load detection section  39  while the step load is detected by the step load detection section  173  in  FIGS. 6(   a ) and  6 ( b ). 
     Since the control section  56  decides the inclination of the vehicle body and the state of the occupant  85 , the falling down detection of the vehicle can be carried out with reliability. By carrying out the reliable falling down detection, when the vehicle falls down, the occupant&#39;s seat  31  can be released with certainty from the seat support member  47 . 
     The occupant&#39;s seat described above lands, after it is released from the vehicle body, on the ground surface and covers the waist part and the thigh parts of the occupant. It is more desirable if the occupant&#39;s seat can cover the back part in addition to the waist part and the thigh parts of the occupant. An occupant&#39;s seat which can cover also the back part of the occupant is described in connection with the following embodiment 2. 
     Now, the embodiment 2 of the present invention is described with reference to the drawings. 
     Referring to  FIG. 9 , a description of a common structure to that of  FIG. 2  is omitted using like reference symbols. An occupant&#39;s seat  31 B has an impact absorbing member  94  built in a rear portion thereof, and this impact absorbing member  94  slidably expands when the occupant&#39;s seat  31 B is released from the seat support member  47  connected to the right seat rail  25 . Now, an expansion apparatus for the impact absorbing member  94  is described. 
     The expansion apparatus  95  includes an inflator  96  provided on the bottom plate  33  for generating gas instantaneously so as to play a role as an expansion power source for the impact absorbing member  94 , a cylinder  98  connected to the inflator  96  through a pipe  97  and extending in the downward direction, a piston  99  built in the cylinder  98 , and a piston rod  101  extending from the piston  99  and having an impact absorbing member  94  provided at an end thereof. 
     A female terminal  103  with which a male terminal  102  of the inflator  96  is fitted is attached to the seat support member  47 , and this female terminal  103  is connected to the control section  56 . The female terminal  103  and the male terminal  102  are terminals of a structure by which they come off simply when the occupant&#39;s seat  31 B is released from the seat support member  47 . 
     If an instruction is issued from the control section  56  to the inflator  96  through the female terminal  103  and the male terminal  102  when the vehicle falls down, then the inflator  96  generates gas instantaneously. This gas flows into a lower chamber in the cylinder  98  through the pipe  97  so that the piston  99  and the piston rod  101  are pushed out upwardly and the impact absorbing member  94  is pushed out outwardly of the occupant&#39;s seat  31 B. Now, the operation of sliding expansion of the impact absorbing member is described. 
     Referring to  FIG. 10(   a ), the occupant&#39;s seat  31 B is released from the seat support member  47  while the occupant  85  remains seated thereon when the vehicle falls down and moves to the left side as indicated by an arrow mark ( 4 ). At this time, if an expansion instruction is issued from the control section  56  to the inflator  96 , then the impact absorbing member  94  slidably expands upwardly as indicated by an arrow mark ( 5 ). 
     In  FIG. 10(   b ), since the occupant  85  lands on the ground surface  87  while it remains seated on the occupant&#39;s seat  31 B, the waist part  92  and the thigh parts  93  of the occupant  85  are covered. Also the back part  104  of the occupant  85  is covered with the impact absorbing member  94 . 
     In the occupant restraining apparatus  30 B, when the occupant&#39;s seat  31 B is released from the seat support member  47 , since the impact absorbing member  94  built in a rear portion of the occupant&#39;s seat  31 B slidably expands, the occupant  85  can be covered with the occupant&#39;s seat  31 B and the impact absorbing member  94 . In particular, the occupant&#39;s seat  31 B can be interposed between the occupant  85  and the ground surface  87  and so forth and also the impact absorbing member  94  can be interposed. Now, a flow until the impact absorbing member is expanded when the motorcycle falls down is described. 
     As illustrated in  FIG. 11 , at step ST 11 , it is confirmed whether or not the seatbelt detection section is ON, and if the result of the confirmation is YES, then the processing advances to step ST 13 , but if the result of the confirmation is NO, then the processing advances to step ST 12 . In particular, it is confirmed by the seatbelt detection section  63  of the contact type whether or not the tongue  61  is mounted fully on the buckle  62  as shown in  FIG. 3(   b ). 
     At step ST 12 , an alarm is issued. In particular, a seatbelt wearing warning to the occupant is displayed on the meter panel  24  as shown in  FIG. 3(   a ). 
     At step ST 13 , it is confirmed whether or not the bank angle detection section is ON, and if the confirmation is YES, then the processing advances to step ST 15 , but if the confirmation is NO, then the processing advances to step ST 14 . In particular, the rotational angle of the left step  18  is detected by the left bank angle detection section  77  as illustrated in  FIG. 5(   b ). 
     At step ST 14 , it is confirmed whether or not the seat load detection section is OFF, and if the confirmation is YES, then the processing advances to step ST 15 , but if the confirmation is NO, then the processing returns to step ST 13 . At step ST 14 , the seat load detection section  39  in  FIG. 2  detects the OFF state such that it is decided by the seat load detection that the occupant has moved in a direction away from the vehicle even if it is detected that the bank angle does not reach a predetermined angle at which falling down is decided. 
     At step ST 15 , the seat lock is released. In particular, the seat lock section  52  cancels the connection to the releasing mechanism  40  by operation of the actuator  55  as illustrated in  FIG. 7(   a ). 
     At step ST 16 , the impact absorbing member is expanded. In particular, an expansion instruction is issued from the control section  56  to the inflator  96  to slidably expand the impact absorbing member  94  upwardly as indicated by an arrow mark ( 5 ) as shown in  FIG. 10(   a ). 
     It is to be noted that the confirmation carried out at step ST 14  regarding whether or not the seat load detection section is OFF may be replaced by a confirmation of whether or not the step load detection section  173  in  FIGS. 6(   a ) and  6 ( b ) is OFF. 
     In addition, while the occupant&#39;s seat of the embodiment 2 is configured such that the impact absorbing member is slidably expanded after release from the vehicle body, the expansion method of the impact absorbing member may be different from the sliding method. An example wherein the impact absorbing member is rotationally expanded is described in connection with the next embodiment 3. 
     Now, the embodiment 3 of the present invention is described with reference to the drawings. 
     Referring to  FIG. 12 , a description of a common structure to that of  FIG. 2  is omitted using like reference symbols. A occupant&#39;s seat  31 C has an impact absorbing member  105  built in a rear portion thereof, and the impact absorbing member  105  rotationally expands when the occupant&#39;s seat  31 C is released from the seat support member  47 . The impact absorbing member  105  is held for rotation on the occupant&#39;s seat  31 C by a pin  106 . Now, an expansion apparatus of the impact absorbing member  105  is described. 
     The expansion apparatus  107  includes an inflator  108  which is an expansion power source for the impact absorbing member  105 , a pipe  109 , a cylinder  111 , a piston  112 , a piston rod  113 , and a link  114  for linking the piston rod  113  and the impact absorbing member  105  to each other. 
     A female terminal  116  with which a male terminal  115  of the inflator  108  is mated is attached to the seat support member  47 , and the female terminal  116  is connected to the control section  56 . The female terminal  116  and the male terminal  115  are terminals of a structure with which they come out simply when the occupant&#39;s seat  31 C is released from the seat support member  47 . 
     If an instruction is issued from the control section  56  to the inflator  108  when the vehicle falls down, then the inflator  108  generates gas instantaneously, and this gas flows into a lower chamber in the cylinder  111 . Since the piston  112 , piston rod  113  and link  114  are pushed upwardly by the gas, the impact absorbing member  105  rotates upwardly around the pin  106 . Now, the operation of the rotational expansion of the impact absorbing member is described. 
     Referring to  FIGS. 13(   a ) and ( b ), the occupant&#39;s seat  31 C is released from the seat support member  47  while the occupant  85  remains seated thereon when the vehicle falls down and moves to the left side as indicated by an arrow mark ( 6 ) as illustrated in  FIG. 13(   a ). At this time, if an expansion instruction is issued from the control section  56  to the inflator  108 , then the impact absorbing member  105  rotationally expands upwardly as indicated by an arrow mark ( 7 ). 
     In  FIG. 13(   b ), since the occupant  85  lands on the ground surface  87  while it remains seated on the occupant&#39;s seat  31 C, the waist part  92  and the thigh parts  93  of the occupant  85  are covered. Further, also the back part  104  of the occupant  85  is covered with the impact absorbing member  105 . 
     In the occupant restraining apparatus  30 C, when the occupant&#39;s seat  31 C is released from the seat support member  47 , the impact absorbing member  105  built in the rear portion of the occupant&#39;s seat  31  is rotationally expanded, and consequently, the occupant  85  can be covered with the occupant&#39;s seat  31 C and the impact absorbing member  105 . In other words, the occupant&#39;s seat  31 C can be interposed between the occupant  85  and the ground surface  87  or the like and also the impact absorbing member  105  can be interposed. 
     While, in the embodiment 2 and the embodiment 3, the impact absorbing member is built in the occupant&#39;s seat, this impact absorbing member may be an airbag. An occupant&#39;s seat in which an airbag is built is described in connection with the following embodiment 4. 
     Now, the embodiment 4 of the present invention is described with reference to the drawings. 
     Referring to  FIG. 14 , the description of a common structure to that of  FIG. 2  is omitted using like reference symbols. An occupant&#39;s seat  31 D includes an impact absorbing member provided at a rear portion thereof, and this impact absorbing member is an airbag  117 . Now, a configuration of an airbag module which includes the folded airbag  117  is described. 
     The airbag module  118  includes an accommodation box  119  contacting with the cushion  34  in the inside of the occupant&#39;s seat  31 D, an inflator  121  attached to a bottom portion of the accommodation box  119 , an airbag  117  attached to the bottom portion of the accommodation box  119  in such a manner as to cover the inflator  121  and held in a folded state, and a lid  122  connected to the accommodation box  119  and covering the internal airbag  117 . 
     A cutaway portion  123  which is broken when the airbag  117  is inflated and expanded is formed on the inner face of the front side of the lid  122 . Further, on the inner face of the rear side of the lid  122 , a connecting portion  124  is formed which plays a role of a hinge when the lid  122  is opened by the inflation expansion of the airbag  117 . 
     A female terminal  126  with which a male terminal  125  of the inflator  121  is mated is attached to the seat support member  47 , and the female terminal  126  is connected to the control section  56 . The female terminal  126  and the male terminal  125  are terminals of a structure with which they come off simply when the occupant&#39;s seat  31 D is released from the seat support member  47 . Now, operation of the inflation expansion of the airbag is described. 
     Referring to  FIG. 15(   a ), the occupant&#39;s seat  31 D is released from the seat support member  47  while the occupant  85  remains seated thereon and moves to the left side as indicated by an arrow mark ( 8 ) when the vehicle falls down. At this time, if an expansion instruction is issued from the control section  56  to the inflator  121 , then the airbag  117  inflates and expands upwardly as indicated by an arrow mark ( 9 ). 
     In  FIG. 15(   b ), since the occupant  85  lands on the ground surface  87  while it remains seated on the occupant&#39;s seat  31 D, the waist part  92  and the thigh parts  93  of the occupant  85  are covered. Further, also the back part  104  of the occupant  85  is covered with the airbag  117  in the inflated and expanded state. In particular, the occupant&#39;s seat  31 D is interposed between the occupant  85  and the ground surface  87  or the like and the airbag  117  can be interposed. 
     While, in the description of the occupant restraining apparatus given above, the structure wherein the occupant&#39;s seat is released sidewardly from the vehicle body when the vehicle falls down, when the vehicle collides at the front face thereof, also there is the possibility that the occupant&#39;s seat may be released forwardly. An example which prevents the occupant&#39;s seat from being released forwardly when the vehicle collides at the front face thereof is described in connection with the following embodiment 5. 
     Now, the embodiment 5 of the present invention is described with reference to the drawings. 
     Referring to  FIG. 16 , the description of a common structure to that of  FIG. 2  is omitted using like reference symbols. An occupant&#39;s seat  131  includes a bottom plate  33 , a cushion  34  and a skin  35 , and includes a releasing mechanism  140  provided at a front portion of the bottom plate  33  which can be released from the right seat rail  25  together with the occupant when the motorcycle  10  in  FIG. 1  falls down. 
     It is to be noted that, since the structure of the releasing mechanism  140  is similar to that of the releasing mechanism  40  (refer to  FIG. 2 ), description thereof is omitted. 
     Further, an abutting portion  147  for being abutted with a pawl member hereinafter described when the motorcycle collides at the front face thereof is provided at a rear portion of the bottom plate  33 . The abutting portion  147  includes an inclination member  151  provided on the front side and having a lower end  149  disposed on the front side with respect to an upper end  148  thereof, another inclination member  154  disposed on the rear side with respect to the inclination member  151  and having a lower end  153  disposed on the front side with respect to an upper end  152  thereof, an upper side member  155  which connects the inclination member  154  and the inclination member  151  to each other, and an abutting member  143  connected to the inclination member  154  and formed along the shape of the pawl member. 
     Meanwhile, a seat support member  156  on which the bottom plate  33  of the occupant&#39;s seat  131  is placed is provided on the right seat rail  25 , and a well-known seat lock section  157  to which a lock pin  142  of the releasing mechanism  140  is removably connected is provided at a front portion of the seat support member  156 . 
     Meanwhile, the seat support member  156  includes a cylinder lock  159  and an actuator  161  connected to the seat lock section  157  by a wire  158 , and a control section  162  for receiving a signal of the seat load detection section  39  through the male terminal  49  and the female terminal  51  and issuing an operation instruction to the actuator  161 . 
     In addition, a pawl member  163  (details are hereinafter described) with which the abutting portion  147  provided at a rear portion of the occupant&#39;s seat  131  is abutted is provided at a rear portion of the seat support member  156 . 
     In particular, the occupant&#39;s seat  131  and the right seat rail  25  are assembled by inserting the hook  38  into the set stay  48 , connecting the lock pin  142  to the seat lock section  157  through an opening  164  of the seat support member  156 , fitting the male terminal  49  into the female terminal  51  through an opening  165  of the seat support member  156  and disposing the pawl member  163  in the inside of the abutting portion  147 . 
     It is to be noted that the surface shape of the abutting member  143  of the abutting portion  147  and the shape of a receiving face  166  of the pawl member  163  are formed so as to coincide with each other. Now, a detailed structure of the pawl member  163  is described. 
     Referring to  FIG. 17(   a ), the pawl member  163  is formed so as to be bent rearwardly from the seat support member  156 . Further, the pawl member  163  is formed such that the widthwise dimension thereof in the vehicle widthwise direction (leftward and rightward direction in  FIG. 17(   a ) decreases toward the rear. 
     As shown in  FIG. 17(   b ), the pawl member  163  is formed in a trapezoidal shape as viewed in plan. If the inner face  167  of the abutting portion (reference numeral  147  of  FIG. 16)  of the occupant&#39;s seat (reference numeral  131  of  FIG. 16 ) is indicated by a phantom line, then since a left side face  168  and a right side face  169  of the pawl member  163  do not contact with the inner face  167 , the occupant&#39;s seat becomes liable to be released to the left or right in comparison with that in a case wherein they contact with the inner face  167 . Now, the operation of the occupant&#39;s seat released from the vehicle body when the motorcycle  10  in  FIG. 1  collides at the front face thereof and the vehicle falls down sidewardly is described. 
     A description is given under the assumption that the seat lock is released in  FIGS. 18(   a ),  18 ( b ) and  18 ( c ). 
     In  FIG. 18(   a ), when the motorcycle  10  in  FIG. 1  collides at the front face thereof, if the occupant&#39;s seat  131  moves forwardly as indicated by an arrow mark ( 10 ), then the abutting member  143  of the abutting portion  147  is brought into abutment with the receiving face  166  of the pawl member  163  as shown in  FIG. 18(   b ). 
     On the bottom plate  33  of the occupant&#39;s seat  131 , the abutting portion  147  which is abutted with the pawl member  163  on the seat support member  156  is provided on the bottom plate  33  of the occupant&#39;s seat  131 . As the abutting member  143  of the abutting portion  147  is abutted with the receiving face  166  of the pawl member  163 , forward release of the occupant&#39;s seat  131  can be stopped. 
     If the vehicle subsequently begins to fall down sidewardly, then the occupant&#39;s seat  131  rides on the pawl member  163  and begins to be released from the seat support member  156  as shown in  FIG. 18(   c ). 
     It is to be noted that, while, in the embodiment 5, the releasing mechanism  140  is provided only at a front portion of the bottom plate  33  of the occupant&#39;s seat  131  as shown in  FIG. 16 , the releasing mechanism  140  may be provided at each of a front portion and a rear portion of the bottom plate  33 . 
     While, in the embodiment 5, the abutting portion  147  and the pawl member  163  are used as means for stopping the occupant&#39;s seat  131  from being released forwardly, different restriction means is described in the following description of an embodiment 6. 
     Now, the embodiment 6 of the present invention is described with reference to the drawings. 
     Referring to  FIGS. 19(   a ) to  19 ( c ), the description of a common structure to that of  FIGS. 18(   a ) to  18 ( c ) is omitted using like reference symbols. As shown in  FIG. 19(   a ), the occupant restraining apparatus  190  includes an abutting portion  192  provided at a rear portion of the bottom plate  33  of an occupant&#39;s seat  191 . 
     The abutting portion  192  includes an inclination member  151 , another inclination member  195  provided on the rear side with respect to the inclination member  151  and having a lower end  194  disposed on the front side with respect to an upper end  193  thereof, an upper side member  155 , and a bar-like abutting member  196  extending downwardly from the upper side member  155  and further extending in the vehicle widthwise direction. 
     Meanwhile, a bar-like member  197  formed so as to be bent rearwardly for restricting forward movement of the abutting member  196  is provided on the seat support member  156 . 
     When the motorcycle  10  in  FIG. 1  collides at the front face thereof, if the seat lock is in a released state, then the occupant&#39;s seat  191  moves forwardly as indicated by an arrow mark ( 11 ). As a result, the abutting member  196  of the abutting portion  192  is brought into abutment with the bar-like member  197  on the seat support member  156  as shown in  FIG. 19(   b ). 
     On the bottom plate  33  of the occupant&#39;s seat  191 , the abutting member  196  for being abutted with the bar-like member  197  on the seat support member  156  is provided. As the abutting member  196  is abutted with the bar-like member  197 , forward release of the occupant&#39;s seat  191  can be stopped. 
     Then, if the vehicle begins to fall down forwardly, then the occupant&#39;s seat  191  rides on the bar-like member  197  and begins to be released from the seat support member  156  as shown in  FIG. 19(   c ). 
     While, in the embodiment 6, the abutting member  196  and the bar-like member  197  are used as means for stopping the occupant&#39;s seat  191  from being released forwardly, further restriction means is described in the following description of an embodiment 7. 
     Now, the embodiment 7 of the present invention is described with reference to the drawings. 
     Referring to  FIGS. 20(   a ) to  20 ( c ), the description of a common structure to that of  FIGS. 18(   a ) to  18 ( c ) is omitted using like reference symbols. As shown in  FIG. 20(   a ), in an occupant restraining apparatus  200 , an abutting portion  202  is provided at a rear portion of the bottom plate  33  of an occupant&#39;s seat  201 . 
     The abutting portion  202  includes an inclination member  151 , another inclination member  205  provided on the rear side with respect to the inclination member  151  and having a lower end  204  disposed on the front side with respect to an upper end  203  thereof, and an upper side member  155 . 
     Meanwhile, on the seat support member  156 , an inclination member  208  having a lower end  207  disposed on the front side with respect to an upper end  206  thereof is provided. 
     When the motorcycle  10  in  FIG. 1  collides at the front face thereof, if the seat lock is in a released state, then the occupant&#39;s seat  201  moves forwardly as indicated by an arrow mark ( 12 ). As a result, the inclination member  205  of the abutting portion  202  is brought into abutment with the inclination member  208  on the seat support member  156  as shown in  FIG. 20(   b ). 
     On the bottom plate  33  of the occupant&#39;s seat  201 , the inclination member  205  for abutting with the inclination member  208  on the seat support member  156  is provided. As the inclination member  205  is brought into abutment with the inclination member  208 , forward release of the occupant&#39;s seat  201  can be stopped. 
     Then, when the vehicle begins to fall down sidewardly, the occupant&#39;s seat  201  rides on the inclination member  208  and begins to be released from the seat support member  156  as shown in  FIG. 20(   c ). 
     While, in the occupant&#39;s seats described above, the lock pin is disposed at a position higher than that of the bottom plate, the lock pin may be disposed lower than the bottom plate if landing of the occupant&#39;s seat is stabilized when the occupant is released from the vehicle body side together with the occupant&#39;s seat and lands. A particular example of this is described in the following description of an embodiment 8. 
     Now, the embodiment 8 of the present invention is described with reference to the drawings. 
     Referring to  FIG. 21 , the description of a common structure to that of  FIG. 2  is omitted using like reference symbols. An occupant&#39;s seat  211  includes a bottom plate  33 , a cushion  34  and a skin  35 , and further includes a releasing mechanism  220  (details are hereinafter described) provided at a rear portion of the bottom plate  33  such that it can be released from the right seat rail  25  together with the occupant when the motorcycle  10  in  FIG. 1  falls down. 
     The releasing mechanism  220  includes a recessed portion  221  recessed upwardly from the bottom plate  33 , a lock pin  222  provided for upward and downward movement in the recessed portion  221  and removably attached to a well-known seat lock section  212  provided on the seat support member  47 , stoppers  223  and  224  attached to the opposite end portions of the lock pin  222 , and compression springs  225  and  226  attached between the stoppers  223  and  224  and the cushion  34 . 
     If upward force acts upon the lock pin  222 , then since the lock pin  222  moves upwardly, the compression springs  225  and  226  are placed into a compressed state. In other words, when upward force acts upon the lock pin  222 , the lock pin  222  does not project downwardly farther than the bottom plate  33 . Now, the operation of the occupant&#39;s seat  211  is described. 
     Referring to  FIGS. 22(   a ) and  22 ( b ), the description of a common structure to that of  FIGS. 7(   a ) and  7 ( b ) is omitted using like reference symbols. 
     When the motorcycle  10  in  FIG. 1  falls down to the left side, as shown in  FIG. 22(   a ), if the actuator  55  operates in accordance with an instruction of the control section  56  to pull the wire  53  to the front side, then the seat lock section  212  cancels its connection to the releasing mechanism  220 . Consequently, the occupant&#39;s seat  211  is released leftwardly sidewards as indicated by an arrow mark ( 13 ) from the seat support member  47  while the occupant  85  remains seated thereon. 
     In  FIG. 22(   b ), since the occupant  85  lands on the ground surface  87  while it remains seated on the occupant&#39;s seat  211 , the waist part  92  and the thigh parts  93  of the occupant  85  are covered with the occupant&#39;s seat  211 . At this time, the lock pin  222  of the releasing mechanism  220  contacts with the ground surface  87  and compresses the compression springs  225  and  226 . When the occupant&#39;s seat  211  lands on the ground surface  87 , the lock pin  222  does not project downwardly farther than the bottom plate  33 , unique occupant action after falling down can be prevented. 
     It is to be noted that, while, in the embodiments, the occupant restraining apparatus according to the present invention is applied to a motorcycle, it can be applied also to a three-wheeled vehicle and a four-wheeled vehicle such as a buggy and a jeep and may be applied to general vehicles. 
     In addition, while, in the embodiments, the expansion power source for the impact absorbing member in the present invention is formed applying an inflator, a structure wherein a compression spring is provided between the inner bottom face of the cylinder and the lower face of the piston may be applied instead. In the structure which uses a compression spring, before release of the occupant&#39;s seat, the compression spring is in a compressed state, and after release of the occupant&#39;s seat, since the stopper which has held the compression spring comes off, the piston moves upwardly by an expanding action of the compression spring. As a result, the impact absorbing member is expanded upwardly. 
     Further, while, in the embodiments, the seat load in the present invention is detected by the seat load detection section provided on the bottom plate of the occupant&#39;s seat, the seat load detection section may be provided on the seat supporting member (vehicle body side) so that it detects the seat load. Where the seat load detection section is provided on the seat supporting member (vehicle body side), the male terminal and the female terminal described in the description of the embodiments become unnecessary. 
     Further, while, in the embodiments, the seatbelt detection section in the present invention is formed applying that of the contact type, that of the non-contacting type may be applied. 
     Further, while, in the embodiments, the warning notification section in the present invention is formed applying a type wherein a warning is displayed on the meter panel, that of another type wherein warning sound is emitted may be adopted. 
     The occupant restraining apparatus of the present invention is suitable for a motorcycle. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.