Abstract:
Vehicle seat devices are provided with: a backrest; side supports that are disposed on both sides of the backrest, and that have protruding sections that protrude further forward than the backrest; a mechanism for adjusting the degree of restraint that changes the width of the protruding sections; a frame disposed inside the side supports; and a movable member that is disposed on the frame, and that displaceably holds the ends of a side surface leather material of the side supports in relation to the frame.

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicular seat device (vehicular seat devices) having side supports on both sides of a backrest. 
     BACKGROUND ART 
     Heretofore, vehicular seat devices have widely been known, which include side supports on both sides of a backrest for restraining a passenger in a vehicle, in order to prevent the passenger from becoming tilted in attitude under centrifugal forces while the vehicle is traveling. 
     As one type of such a vehicular seat device, a vehicular seat device is disclosed in which portions (protruding portions) of side supports, which project forwardly from a backrest, have widths that are changed in order to enable the extent to which the passenger is restrained to be variable (Japanese Laid-Open Patent Publication No. 06-284942). 
     SUMMARY OF INVENTION 
     Usually, each of the side supports has an upholstery cover layer, an end portion of which is introduced into the side support (or the backrest) between the backrest and the side support. In this manner, the upholstery cover layer is fixed to a frame disposed in the side support while the upholstery cover layer is stretched sufficiently. Thus, the end portions of the upholstery cover layers are concealed from view, and surfaces of the side supports are prevented from becoming wrinkled. 
     If the above structure were applied to Japanese Laid-Open Patent Publication No. 06-284942, then the upholstery cover layers would tend to resist an attempt to increase the widths of the protruding portions. Therefore, the widths of the protruding portions could not be increased adequately, i.e., the distance between the protruding portions thereof could not be reduced sufficiently. 
     If the tension of the upholstery cover layers of the side supports is decreased in an effort to reduce the resistance imposed by the upholstery cover layers, if the width of the protruding portions is reduced, the surfaces of the side supports are likely to become wrinkled, thereby making the side supports aesthetically poor in appearance. 
     The present invention has been made in light of the aforementioned difficulties. An object of the present invention is to provide a vehicular seat device having protruding portions, the widths of which are variable to an increased extent, without making the protruding portions aesthetically poor in appearance. 
     According to the present invention, there is provided a vehicular seat device comprising a backrest, side supports disposed on respective sides of the backrest and having respective protrusions that project forwardly of the backrest, means for variably changing widths of the protrusions, a frame disposed in the side supports, and a movable assembly mounted on the frame, wherein the side supports include respective covering layers, respective ends of the covering layers being held by the movable assembly for displacement with respect to the frame (claim  1 ). 
     Preferably, the movable assembly is mounted on the frame for displacement in a thicknesswise direction of the backrest, and for bearing a rearward load applied to the backrest (claim  2 ). 
     Preferably, the movable assembly further comprises a pressure bearing member held in contact with the backrest, and a flexible member mounted on the pressure bearing member, wherein the ends of the covering layers of the side supports are engaged by the flexible member (claim  3 ). 
     Preferably, the vehicular seat device further comprises engaging members mounted respectively on the ends of the covering layers of the side supports, the engaging members extending in one direction, wherein the flexible member includes engaging wires that extend along a direction in which the backrest extends and which are engaged by the engaging members (claim  4 ). 
     Preferably, the vehicular seat device further comprises an airbag unit disposed in one of the side supports, the airbag unit being inflatable outwardly, a webbing disposed around the airbag unit, and a webbing support held by the frame and supporting the webbing, wherein the engaging wires are offset from the webbing support along the direction in which the backrest extends (claim  5 ). 
     Preferably, the pressure bearing member is shaped like a plate and includes a constricted portion, which is narrow in a widthwise direction of the backrest, and the engaging wires are disposed adjacent to the constricted portion (claims  6  and  7 ). 
     According to the invention recited in claim  1 , since the ends of the covering layers of the side supports are displaceable with respect to the frame, when the widths of the protrusions are increased, the ends of the covering layers are displaced toward the protrusions, thereby pulling portions of the covering layers, which have been positioned in regions (within the side supports) that are concealed from view, onto the surfaces of the protrusions. Since resistance imposed from the covering layers when the widths of the protrusions are increased is reduced, the widths of the protrusions are capable of being changed to an increased extent. 
     When the widths of the protrusions are reduced, the ends of the covering layers are displaced in directions away from the protrusions, thereby pulling portions of the covering layers, which correspond to the protrusions, into the side supports. The surfaces of the side supports are thus prevented from wrinkling, and hence from becoming poor in appearance. 
     According to the invention recited in claim  2 , when the driver on the vehicular seat device is subjected to a rearward load toward the backrest due to a vehicle collision or the like, the movable assembly bears the rearward load toward the backrest and displaces the backrest relatively in a rearward direction. Therefore, any impact on the driver is reduced. 
     If the ends of the covering layers of the side supports are fixed to the frame by fixed members, then if a vehicle collision occurs, such fixed members tend to interfere with other members that bear the load on the backrest, possibly preventing the backrest from being displaced relatively in a rearward direction. The vehicular seat device according to the present invention is free of such a drawback. 
     According to the invention recited in claim  3 , when the widths of the protrusions are increased, the flexible member becomes elastically deformed, thereby displacing the ends of the covering layers of the side supports toward the protrusions. By reducing the widths of the protrusions, the ends of the covering layers are displaced in directions away from the protrusions under a recovering force from the flexible member. 
     In addition to the flexible member being elastically deformed, if the pressure bearing member also is displaced with respect to the frame, then it is possible for the ends of the covering layers to be displaced to an increased extent. 
     According to the invention recited in claim  4 , since the engaging members, which extend in one direction, engage with the engaging wires, variation in the tension that acts on the covering layers along the direction in which the backrest extends is made smaller and more uniform than if the ends of the covering layers of the side supports were held on the flexible member by C-rings or the like. 
     According to the invention recited in claim  5 , the airbag unit is disposed in one of the side supports, and the engaging wires are offset from the webbing support along the direction in which the backrest extends. Therefore, if the flexible member becomes elastically deformed, or if the pressure bearing member is displaced in the thicknesswise direction of the backrest, the webbing support and the flexible member are prevented from interfering with each other. 
     According to the invention recited in claim  6  or  7 , since the engaging wires are disposed adjacent to the constricted portion, the engaging wires or the covering layers of the side supports can be disposed in spaces created on both sides of the constricted portion. Therefore, the movable assembly is rendered compact as a whole. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a vehicular seat device according to a first embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of a seat back according to the first embodiment; 
         FIG. 3  is a rear perspective view of a frame and a movable member according to the first embodiment; 
         FIG. 4  is a cross-sectional view taken along line IV-IV of  FIG. 1 , showing air pouches in a collapsed condition; 
         FIG. 5  is a cross-sectional view similar to  FIG. 4 , showing the air pouches in an expanded condition; 
         FIG. 6  is a rear perspective view, partially cut away, of the seat back according to the first embodiment; 
         FIG. 7  is a graph showing a relationship between a load acting on a backrest and a rearward stroke of the backrest; 
         FIG. 8  is a schematic perspective view showing the structure of a vehicular seat device according to a comparative example shown in  FIG. 7 ; and 
         FIG. 9  is a rear perspective view of a frame and a movable member according to a second embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Vehicular seat devices according to preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. For facilitating understanding of the present invention, a left-hand side of a vehicular seat device as viewed from the perspective of a passenger seated on the vehicular seat device is denoted by the arrow “L”, a right-hand side of the vehicular seat device is denoted by the arrow “R”, a front side of the vehicular seat device is denoted by the arrow “Fr”, and a rear side of the vehicular seat device is denoted by the arrow “Rr”. 
     (First Embodiment) 
     A vehicular seat device (first seat device)  10  according to a first embodiment of the present invention will be described below with reference to  FIGS. 1 through 7 . In the following description, when it is necessary to distinguish between left and right components, the components are denoted by reference characters together with a suffix “L” or “R”. When the components do not need to be distinguished from each other, the components are denoted by reference characters alone without the appended suffixes. 
     The first seat device  10  may be used as a driver&#39;s seat for automobiles (vehicles), for example. As shown in  FIG. 1 , the first seat device  10  includes a seat cushion  12  mounted on a non-illustrated vehicle body for supporting the buttocks and thighs of the driver, a seat back  14  tiltably supported on the rear end of the seat cushion  12  for supporting the back of the driver, and a headrest  16  vertically and adjustably mounted on the upper end of the seat back  14  for supporting the head of the driver. 
     The seat back  14  has a backrest  18 , which serves as a lateral central area of the seat back  14 , and a pair of side supports  20 L,  20 R. The side supports  20 L,  20 R are disposed on respective left and right sides of the backrest  18 . Each of the side supports  20  projects in a forward direction from the front surface of the backrest  18 , and along a vertical direction in which the backrest  18  extends, so as to support a side of the driver. 
     The headrest  16  has a headrest body  22  and two stays  24 L,  24 R that extend in a downward direction parallel to each other from the lower end of the headrest body  22 . The headrest  16  is mounted on the seat back  14 , with the stays  24 L,  24 R being inserted in respective stay supports  26 L,  26 R on the upper end of the seat back  14 . 
     As shown in  FIG. 2 , the seat back  14  includes a seat back frame  28 , a back pad  30  covering the seat back frame  28 , and an upholstery cover layer  32  covering the back pad  30 . 
     As shown in  FIGS. 2 and 3 , the seat back frame  28  (hereinafter referred to as a “frame  28 ”), which serves as a skeleton of the seat back  14 , is tiltably coupled to the rear end of a lower frame  33 , which serves as a skeleton of the seat cushion  12 , so that the frame  28  can be tilted back and forth. The frame  28  includes a main frame  34 , which is substantially inversely U-shaped as viewed in front elevation. 
     The main frame  34  includes left and right side frame members  36 L,  36 R, and a top frame member  38  interconnecting upper portions of the side frame members  36 L,  36 R. The main frame  34  is made of a material, e.g., a metal material such as steel, aluminum, or the like, which is sufficiently rigid so as not to become deformed under loads. 
     The stay supports  26 L,  26 R, in which the stays  24 L,  24 R of the headrest  16  are inserted, are fixedly mounted on the top frame member  38 . An airbag device  40  for protecting the driver upon the occurrence of a vehicle collision is mounted on a right-hand side of the side frame member  36 R. 
     As shown in  FIGS. 2 through 5 , the airbag device  40  includes an airbag unit  42 , which is capable of being inflated when a propellant is ignited therein, two webbings  46   a ,  46   b  (see  FIGS. 4 and 5 ) that direct the inflating pressure of the airbag unit  42  toward a seam of the upholstery cover layer  32 , which serves as a rupturable region  44 , and a webbing support  48  for supporting the webbings  46   a ,  46   b.    
     The webbing support  48  is mounted on a fixed frame member  50 , which is disposed substantially in a longitudinally central location on the side frame member  36 R. The fixed frame member  50  is positioned within the main frame  34 . The webbing support  48  includes a front wire  52 , which is positioned forwardly of the airbag unit  42 , and a rear wire  54 , which is positioned rearwardly of the airbag unit  42 . Respective ends of the front wire  52  and the rear wire  54  are coiled around the fixed frame member  50 . 
     As shown in  FIGS. 4 and 5 , an end of one of the webbings  46   a  is held by the front wire  52 , and an end of the other webbing  46   b  is held by the rear wire  54 . The other ends of the two webbings  46   a ,  46   b  are stitched to the rupturable region  44  of the upholstery cover layer  32 . Since the airbag unit  42  is covered with the side frame member  36 R and the webbings  46   a ,  46   b , an inflating pressure, which is generated upon inflation of the airbag unit  42 , is directed toward the rupturable region  44 . 
     As shown in  FIGS. 2 ,  4  and  5 , the back pad  30 , which serves to produce the shape of the seat back  14 , is made of an elastically deformable material such as soft polyurethane foam, for example. The back pad  30  includes a central pad  56 , which is disposed in a lateral central position, and two side pads  58 L,  58 R, which are disposed on respective left and right sides of the central pad  56 . 
     As shown in  FIG. 2 , the back pad  30  has two grooves  60 L,  60 R defined at respective boundaries between the central pad  56  and the side pads  58 L,  58 R. The grooves  60 L,  60 R include respective vertically extending slits  62 L,  62 R, which are defined through the back pad  30  and extend from a rear surface to a front surface of the back pad  30 . Except for the slits  62 L,  62 R, the central pad  56  and the side pads  58 L,  58 R are joined together integrally at upper and lower portions thereof. The height of the slits  62  lies within a range from 12 cm to 40 cm, for example. 
     The central pad  56  has two insertion holes  64 L,  64 R, which are defined in an upper surface thereof for enabling insertion therein of the stay supports  26 L,  26 R on the upper end of the seat back  14 . The insertion holes  64  extend vertically through an upper wall portion of the back pad  30 . 
     As shown in  FIGS. 4 and 5 , the side pads  58 L,  58 R are disposed in covering relation to the side frame members  36 L,  36 R and have respective protrusions  66 L,  66 R that project forwardly from the front surface of the central pad  56 . The side pads  58  are associated with a restraint adjusting mechanism  68  (see  FIG. 1 ), which acts as a variable means for changing the width of the protrusions  66 L,  66 R. 
     As shown in  FIG. 1 , the restraint adjusting mechanism  68  includes two expandable and shrinkable air pouches (also referred to as “bladders” or “air cells”)  70 L,  70 R (see  FIGS. 4 and 5 ), which are disposed between the side frame members  36 L,  36 R and the side pads  58 L,  58 R, an air supply  74  for supplying compressed air through a tube  72  to the air pouches  70 , and a controller  76  for controlling the air supply  74 . The air supply  74  may comprise an air compressor or the like. The compressed air supplied to the air pouches  70  is discharged by exhaust valves or the like, not shown. The controller  76  may be incorporated in the vehicular seat device  10 , or may be incorporated in an engine control unit (ECU) of the vehicle. 
     As shown in  FIGS. 2 ,  4  and  5 , the upholstery cover layer  32  includes a central cover layer  78  that covers the front and upper surfaces of the central pad  56 , two side covering layers  80 L,  80 R that cover the respective side pads  58 L,  58 R, and a rear covering layer  82  that covers the rear surface of the central pad  56 . The upholstery cover layer  32  as a whole covers the back pad  30  substantially in its entirety. The central cover layer  78  corresponds to front and upper surfaces of the backrest  18  of the seat back  14 , whereas the side covering layers  80  correspond to the side supports  20  (see  FIG. 1 ). 
     As shown in  FIGS. 4 through 6 , the side covering layers  80 L,  80 R include respective covering webs  84 L,  84 R, the widths of which are substantially the same as the height of the slits  62 . The covering webs  84  extend rearwardly from locations corresponding to the slits  62 , through the slits  62  and into the seat back  14 . Respective ends of the covering webs  84  are held by a movable back support assembly  86  (also referred to as a movable assembly herein), which is displaceable with respect to the seat back frame  28 . Engaging members  88 L,  88 R are fixed to respective ends of the covering webs  84 L,  84 R over the entire length thereof. The engaging members  88 L,  88 R are tubular in shape, and may also be referred to as engaging sleeve members. 
     As shown in  FIGS. 2 through 6 , the movable assembly  86  includes two support wires  90   a ,  90   b  connected to the side frame members  36 L,  36 R, a plate-shaped pressure bearing member  92  supported on the support wires  90   a ,  90   b  for bearing rearward loads applied to the backrest  18 , and a flexible member  94 , which is mounted on the rear surface of the pressure bearing member  92  and holds the engaging members  88 . 
     As shown in  FIGS. 3 and 6 , the support wires  90   a ,  90   b  are disposed behind the pressure bearing member  92 , and are joined to and extend between the side frame members  36 L,  36 R. The support wires  90   a ,  90   b  are flexible. 
     As shown in  FIGS. 2 and 3 , the pressure bearing member  92  has a narrow constricted portion  96  positioned substantially centrally in the vertical direction. As shown in  FIGS. 4 and 5 , the pressure bearing member  92  has upper and lower portions (other than the constricted portion  96 ), the width of which is substantially the same as the width of the central pad  56 . As shown in  FIGS. 3 and 6 , the pressure bearing member  92  has a plurality of engaging teeth  98  on a back portion thereof, by which the pressure bearing member  92  is attached to the support wires  90   a ,  90   b , and the flexible member  94  is attached to the pressure bearing member  92 . The layout and number of the support wires  90   a ,  90   b  may be selected as desired. However, according to the present embodiment, the support wire  90   a  that is disposed on the upper portion of the pressure bearing member  92 , and the support wire  90   b  that is disposed on the lower portion of the pressure bearing member  92  allow the pressure bearing member  92  to be supported in a well balanced manner. 
     As shown in  FIGS. 2 ,  3  and  6 , the flexible member  94  includes a laterally extending holding wire  100 , which is held by the constricted portion  96 , and two engaging wires  102 L,  102 R, which are joined to respective left and right sides of the holding wire  100  and hold the engaging members  88 L,  88 R. The flexible member  94  is laterally symmetrically shaped. The holding wire  100  and the engaging wires  102  are made of steel, for example, having a diameter in the range from 3 mm to 6 mm. The length of the holding wire  100  is about one-half the width of the constricted portion  96 . 
     The engaging wires  102 L,  102 R include respective first wires  104 L,  104 R that extend from ends of the holding wire  100  toward the top frame member  38 , second wires  106 L,  106 R that extend from ends of the first wires  104 L,  104 R toward the side frame members  36 L,  36 R, third wires  108 L,  108 R that extend from ends of the second wires  106 L,  106 R toward the lower frame  33 , and fourth wires  110 L,  110 R that extend from ends of the third wires  108 L,  108 R inwardly of the main frame  34 . End portions of the fourth wires  110  are held by the lower end of the pressure bearing member  92 . 
     As shown in  FIGS. 3 and 4 , the second wires  106  extend obliquely rearward from the ends of the first wires  104 , whereas the fourth wires  110  extend obliquely forward from the ends of the third wires  108 . Therefore, a gap is defined in a front-rear direction between the third wires  108  and the pressure bearing member  92  through which the support wire  90   b  is inserted. Accordingly, the flexible member  94  and the support wire  90   b  are prevented from interfering with each other. Upper ends of the first wires  104  are positioned more closely to the lower frame  33  than to the webbing support  48  (see  FIG. 3 ). 
     As shown in  FIG. 6 , the engaging members  88  are attached to the third wires  108  such that the side covering layers  80  are stretched adequately. Since the side covering layers  80  are placed under a predetermined tension, the surfaces of the side supports  20  are prevented from wrinkling. 
     As shown in  FIG. 6 , the third wires  108  are slightly longer than the engaging members  88 . Therefore, any variation in tension that acts in a vertical direction on the side covering layers  80  is minimized, and the tension is more uniform than if the ends of the side covering layers  80  were held on the flexible member  94  by C-rings or the like. 
     Operations of the first seat device  10  to change the restraint will be described below. 
     As shown in  FIG. 4 , when the restraint imposed on the driver by the side supports  20  is small (compressed air is not present in the air pouches  70 ), the ends of the covering webs  84  are held on the third wires  108  by the engaging members  88  with the side covering layers  80  being stretched sufficiently. At this time, the surfaces of the side supports  20  are not wrinkled. 
     Then, as shown in  FIGS. 1 and 5 , the controller  76  controls the air supply  74  to supply compressed air to the air pouches  70 . At this time, the pressure of the compressed air (the expanding pressure of the air pouches  70 ) acts on the protrusions  66  of the side pads  58 . Thus, since the widths of the protrusions  66  are increased, the ends of the covering webs  84  are subjected to tensile forces toward the protrusions  66 . 
     When the ends of the covering webs  84  are subjected to such tensile forces, the support wires  90   a ,  90   b  are elastically deformed in order to displace the flexible member  94  and the pressure bearing member  92  in a forward direction with respect to the frame  28  (see  FIG. 6 , for example). 
     Since moments act on the flexible member  94  in the directions indicated by the arrows A, the flexible member  94  is elastically deformed in an arcuate shape. Further, since the flexible member  94  is held on the pressure bearing member  92  by the engaging teeth  98 , the pressure bearing member  92  also is elastically deformed in unison with the flexible member  94 . As a result, the ends of the covering webs  84  are displaced toward the protrusions  66  until portions of the covering webs  84  are pulled onto the surfaces of the protrusions  66 . Therefore, the widths of the protrusions  66  are increased while minimizing the resistance from the side covering layers  80 . More specifically, as shown in  FIGS. 4 and 5 , the widths of the protrusions  66  grow from W 1  to W 2 . Insofar as the distance between the protrusions  66 L,  66 R is reduced, the protrusions  66 L,  66 R produce increased forces that act to restrain the driver. 
     Thereafter, the controller  76  controls the exhaust valves to discharge compressed air from the air pouches  70 . At this time, the air pouches  70  shrink, thereby reducing the widths of the protrusions  66 . Since the tensile forces that have been acting on ends of the covering webs  84  are removed, the ends of the covering webs  84  are pulled rearwardly under recovering forces from the support wires  90   a ,  90   b , the flexible member  94 , and the pressure bearing member  92 . Consequently, the portions (extra covering portions) of the covering webs  84 , which up till now have been positioned on the surfaces of the protrusions  66 , are pulled rearwardly. Thus, the surfaces of the side supports  20  are prevented from wrinkling and becoming poor in appearance. 
     With the vehicular seat device  10  according to the present embodiment, the support wires  90   a ,  90   b , the pressure bearing member  92 , and the flexible member  94  are elastically deformed in order to make the ends of the covering webs  84  displaceable. The ends of the covering webs  84  can be displaced a greater distance than if only the flexible member  94  were elastically deformed. Therefore, the widths of the protrusions  66  can be changed to an increased extent, thereby enhancing the range within which the restraint on the driver can be varied. 
     According to the present embodiment, the third wires  108  are disposed adjacent to the constricted portion  96  of the pressure bearing member  92 . Thus, the third wires  108  or the covering webs  84  can be disposed in respective spaces, which are created on both sides of the constricted portion  96 . Therefore, the movable assembly  86  is rendered compact as a whole. 
     According to the present embodiment, furthermore, if the driver is subjected to a rearward load toward the backrest  18  due to a vehicle collision or the like, the pressure bearing member  92  bears the rearward load toward the backrest  18 , whereupon the support wires  90   a ,  90   b  become elastically deformed, thereby displacing the backrest  18  and the pressure bearing member  92  rearwardly. Therefore, the impact on the driver is reduced. 
     An impact absorbing effect on the driver will be described in further detail with reference to  FIGS. 7 and 8 . 
       FIG. 7  is a graph showing a relationship between the load that acts on the backrest  18  and the rearward stroke of the front surface of the backrest  18 . In the graph, the solid-line curve P 1  represents data that was plotted when the first seat device  10  was used, whereas the broken-line curve P 2  represents data that was plotted when a vehicular seat device  200  (see  FIG. 8 ) according to a comparative example was used. 
       FIG. 7  shows data obtained when an experiment was conducted on the vehicular seat device (comparative seat device)  200  according to the comparative example and the first seat device  10 , in order to measure relative positional changes of the front surfaces of the backrests  18  when a given static load was applied to the front surfaces of the backrests  18  with the backrests  18  being oriented in a horizontal position (i.e., with the seat devices  200 ,  10  being tilted 90°). 
     Structural details of the comparative seat device  200  will be described below with reference to  FIG. 8 . Only certain details of the comparative seat device  200 , which differ from those of the first seat device  10 , will be described below. In  FIG. 8 , which corresponds to  FIG. 3 , constituent parts that are identical to those shown in  FIG. 3  are denoted using identical reference characters. 
     As shown in  FIG. 8 , the comparative seat device  200  includes fixed members  202 L,  202 R instead of the flexible member  94  of the first seat device  10 . The fixed members  202 , which extend vertically, are positioned rearwardly of the pressure bearing member  92 . Respective ends of the fixed members  202  are fixed to the top frame member  38 , and opposite ends thereof are fixed to the lower portion of the seat back frame  28 . 
     In the experiment that was conducted on the comparative seat device  200 , when a static load was imposed on the backrest  18 , since the rear surface of the pressure bearing member  92  was brought into contact with the fixed members  202 , the backrest  18  was prevented from being displaced rearwardly. On the other hand, the first seat device  10  does not have any member located behind the pressure bearing member  92  that prevents the pressure bearing member  92  from being displaced rearwardly. Accordingly, the stroke over which the backrest  18  of the first seat device  10  was displaced rearwardly is greater than the stroke over which the backrest  18  of the comparative seat device  200  was displaced rearwardly (see  FIG. 7 ). 
     (Second Embodiment) 
     A vehicular seat device (second seat device)  300  according to a second embodiment of the present invention will be described below with reference to  FIG. 9 . Constituent parts of the second embodiment, which are identical to those of the first embodiment, are denoted by identical reference characters, and duplicate descriptions of such parts will be omitted. 
     As shown in  FIG. 9 , the second seat device  300  does not have the support wires  90   a ,  90   b , but has a pressure bearing member  301 , which differs in shape from the pressure bearing member  10  of the first seat device  10 . More specifically, the pressure bearing member  301  comprises a plurality of (three in  FIG. 9 ) laterally extending S-shaped springs  302 . Ends of each of the S-shaped springs  302  are fixed to the side frame members  36 . The first wires  104  and the fourth wires  110  of the flexible member  94  are held by clips on two of the S-shaped springs  302 . The second embodiment offers the same advantages as those of the first embodiment. 
     The present invention is not limited to the first and second embodiments, but may be reduced to practice in various other configurations. For example, the central pad and the side pads may be fully separated from each other. 
     In the vehicular seat device according to the present invention, the flexible member may be dispensed with, and the engaging members may be connected directly to the pressure bearing member. According to such a modification, the ends of the covering webs are displaced as a result of elastic deformation of the support wires and the pressure bearing member. 
     In the vehicular seat device according to the present invention, furthermore, the airbag device may be disposed outside of one of the side supports. According to such a modification, since a webbing support does not need to be mounted on the frame member, the upper ends of the first wires are not limited in position. 
     The restraint adjusting mechanism according to the present invention is not limited to using air pouches to change the widths of the protrusions, but may include plates, which are positionally variable with respect to the side frame members in order to change the widths of the protrusions.