Patent Publication Number: US-2023137554-A1

Title: Vehicle door device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2021-179835, filed on Nov. 2, 2021, the entire content of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a vehicle door device. 
     BACKGROUND DISCUSSION 
     In the related art, there has been a vehicle door device including a first link arm and a second link arm that include a first rotation coupling point with respect to a vehicle body, and a second rotation coupling point with respect to a door of a vehicle. In such a vehicle door device, the door provided in a door opening performs opening-and-closing operation, based on the operation of a link mechanism formed by the first link arm and the second link arm. Furthermore, for example, JP 2006-90097 A discloses a configuration in which each link arm forming a link mechanism is housed at a position outside a door opening mounted on a terminal portion of a vehicle body side portion and inside a weather strip mounted on a vehicle interior side of the door in a case where the door is in a closed state. For example, JP 2008-163693 A discloses a configuration in which such a link mechanism formed by each link arm is combined with a structure in which a guide rail on a vehicle body side and a guide roller unit on a door side engage with each other. 
     However, in a configuration of supporting a door of a vehicle on a vehicle body via the link mechanism formed by the first and second link arms as described above, the first and second link arms are more likely to be brought closer to each other and be linearly aligned in a case where the door is located in the vicinity of a fully closed position. Therefore, there is a problem that it is difficult to stably support the door. 
     A need thus exists for a vehicle door device which is not susceptible to the drawback mentioned above. 
     SUMMARY 
     A vehicle door device includes: first and second link arms that have a first rotation coupling point with respect to a vehicle body and a second rotation coupling point with respect to a door of a vehicle; a door-side engagement portion that is provided at a close-side end portion of the door that opens and closes a door opening of the vehicle based on operation of a link mechanism formed by the first and second link arms; and a vehicle body-side engagement portion that is provided at a close-side end portion of the door opening that the close-side end portion of the door comes into contact with and separates from based on opening-and-closing operation of the door, in which one side of the door-side engagement portion and the vehicle body-side engagement portion includes an axial engagement portion extending in a vertical direction of the vehicle, the other side of the door-side engagement portion and the vehicle body-side engagement portion includes a guide groove having a pair of side wall portions facing each other in a vehicle width direction and extending in an opening-and-closing operation direction of the door, and the axial engagement portion is disposed inside the guide groove at an opening-and-closing operation position in the vicinity of a fully closed position of the door at which the door-side engagement portion and the vehicle body-side engagement portion are engaged with each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein: 
         FIG.  1    is a perspective view of a vehicle door device; 
         FIG.  2    is a perspective view of a vehicle door device; 
         FIG.  3    is a plan view of first and second link arms forming a link mechanism; 
         FIG.  4    is a plan view of first and second link arms forming a link mechanism; 
         FIG.  5    is a plan view of first and second link arms forming a link mechanism; 
         FIG.  6    is a plan view of first and second link arms forming a link mechanism; 
         FIG.  7    is a schematic configuration diagram illustrating a door-side engagement portion and a vehicle body-side engagement portion; 
         FIG.  8    is an explanatory diagram illustrating arrangement of a door-side engagement portion and a vehicle body-side engagement portion; 
         FIG.  9    is a perspective view of a door and a door opening, illustrating arrangement of a door-side engagement portion and a vehicle body-side engagement portion; 
         FIG.  10    is a perspective view illustrating a door-side engagement portion and a vehicle body-side engagement portion; 
         FIG.  11    is a side view illustrating a door-side engagement portion and a vehicle body-side engagement portion; 
         FIG.  12    is a cross-sectional view illustrating a door-side engagement portion and a vehicle body-side engagement portion; 
         FIG.  13    is a cross-sectional view illustrating a door-side engagement portion and a vehicle body-side engagement portion; 
         FIG.  14    is an exploded perspective view illustrating a door-side engagement portion and a vehicle body-side engagement portion; 
         FIG.  15    is a front view of a door-side engagement portion; 
         FIG.  16    is a side view of a door-side engagement portion; 
         FIG.  17    is a perspective view illustrating a first guide member and a fixing bracket constituting an upper vehicle body-side engagement portion; 
         FIG.  18    is a perspective view illustrating a second guide member and a fixing bracket constituting a lower vehicle body-side engagement portion; 
         FIG.  19    is a side view illustrating a second guide member and a fixing bracket; 
         FIG.  20    is a cross-sectional view illustrating a second guide member and a fixing bracket; 
         FIG.  21    is a perspective view illustrating a first guide member and a fixing bracket; 
         FIG.  22    is a plan view of a joint link mechanism forming a connection length variable mechanism provided in a second link arm; 
         FIG.  23    is a plan view of a joint link mechanism; 
         FIG.  24    is a perspective view of a vehicle door device; 
         FIG.  25    is a perspective view of a vehicle door device; 
         FIG.  26    is a plan view of a second link arm including a joint link mechanism; 
         FIG.  27    is an operation explanatory diagram of a second link arm including a joint link mechanism; 
         FIG.  28    is a side view of a second link arm including a joint link mechanism; 
         FIG.  29    is an exploded perspective view of a second link arm including a joint link mechanism; 
         FIG.  30    is a cross-sectional view illustrating a second rotation coupling point with respect to a door of a second link arm and an intermediate coupling point of a joint link mechanism; 
         FIG.  31    is a plan view illustrating an engagement protrusion portion provided on a second link arm and a cam member provided on a door; 
         FIG.  32    is a plan view illustrating an engagement protrusion portion provided on a second link arm and a cam member provided on a door; 
         FIG.  33    is a plan view illustrating an engagement protrusion portion provided on a second link arm and a cam member provided on a door; 
         FIG.  34    is a plan view illustrating an engagement protrusion portion provided on a second link arm and a cam member provided on a door; 
         FIG.  35    is a perspective view of the vicinity of a first rotation coupling point of a second link arm with respect to a vehicle body; 
         FIG.  36    is a cross-sectional view of a first rotation coupling point of a second link arm with respect to a vehicle body; 
         FIG.  37    is a perspective view illustrating a first link arm and an actuator; 
         FIG.  38    is an exploded perspective view illustrating a first link arm and an actuator; 
         FIG.  39    is a side view of a first link arm; 
         FIG.  40    is a cross-sectional view illustrating a distal end bracket, a door bracket, and a friction member which form a second rotation coupling point of a first link arm with respect to a door; 
         FIG.  41    is a side view of the vicinity of a formation portion of a first rotation coupling point of a first link arm provided with an actuator with respect to a vehicle body; 
         FIG.  42    is a perspective view illustrating a guide member and a fixing bracket according to a second embodiment; 
         FIG.  43    is a side view illustrating a guide member and a fixing bracket according to the second embodiment; 
         FIG.  44    is a cross-sectional view illustrating a door-side engagement portion and a vehicle body-side engagement portion according to the second embodiment; 
         FIG.  45    is a cross-sectional view illustrating a door-side engagement portion and a vehicle body-side engagement portion according to the second embodiment; 
         FIG.  46    is an exploded perspective view illustrating a guide member and a fixing bracket according to the second embodiment; 
         FIG.  47    is a perspective view illustrating a guide member and a fixing bracket according to the second embodiment; 
         FIG.  48    is a perspective view illustrating a guide member and a fixing bracket according to a third embodiment; 
         FIG.  49    is a side view illustrating a guide member and a fixing bracket according to the third embodiment; 
         FIG.  50    is a cross-sectional view illustrating a door-side engagement portion and a vehicle body-side engagement portion according to the third embodiment; 
         FIG.  51    is an exploded perspective view illustrating a guide member and a fixing bracket according to the third embodiment; 
         FIG.  52    is a perspective view illustrating a guide member and a fixing bracket according to the third embodiment; 
         FIG.  53    is a plan view of an extension and contraction link mechanism forming a connection length variable mechanism of another example; and 
         FIG.  54    is a plan view of an extension and contraction link mechanism. 
     
    
    
     DETAILED DESCRIPTION 
     First Embodiment 
     Hereinafter, the first embodiment embodying a vehicle door device will be described with reference to the drawings. 
     As illustrated in  FIGS.  1  and  2   , a vehicle  1  of the present embodiment includes a door opening  3  provided on a side surface of a vehicle body  2 . The door opening  3  is provided with a first link arm  11  and a second link arm  12  which support a door  5  of the vehicle  1  at the door opening  3 . 
     More specifically, in the vehicle  1  of the present embodiment, the first and second link arms  11  and  12  each have a first rotation coupling point X 1  with respect to the vehicle body  2  and a second rotation coupling point X 2  with respect to the door  5 . Specifically, the first link arm  11  is coupled to the vehicle body  2  in a state of being axially supported by a support shaft N 1   a  extending in a vertical direction (in  FIG.  1    and  FIG.  2   , a vertical direction), and is coupled to the door  5  in a state of being axially supported by a support shaft N 1   b  extending in the vertical direction. The second link arm  12  is also coupled to the vehicle body  2  in a state of being axially supported by a support shaft N 2   a  extending in the vertical direction, and is also coupled to the door  5  in a state of being axially supported by a support shaft N 2   b  extending in the vertical direction. 
     That is, as illustrated in  FIGS.  3  to  6   , in the vehicle  1  of the present embodiment, the first and second link arms  11  and  12  form a link mechanism  15  having a configuration as a four-joint link. The vehicle  1  of the present embodiment is configured such that the door  5  supported by the door opening  3  is opened and closed based on the operation of the link mechanism  15 . 
     More specifically, as illustrated in  FIGS.  1  and  2   , the vehicle  1  of the present embodiment uses the first and second link arms  11  and  12  to support the door  5  on the door opening  3  on a vehicle rear side (left side in  FIG.  1   , right side in  FIG.  2   ). In the vehicle  1  of the present embodiment, the first and second link arms  11  and  12  each have the first rotation coupling point X 1  rotatably coupled to the vehicle body  2  in the vicinity of a rear edge portion  3   r  of the door opening  3 . In the vehicle  1  of the present embodiment, the first and second link arms  11  and  12  are disposed to be separated from each other in the vertical direction. 
     In the vehicle  1  of the present embodiment, the first link arm  11  is provided above the second link arm  12 . Furthermore, the first link arm  11  has the second rotation coupling point X 2  rotatably coupled to the door  5  at a substantially central position in a horizontal direction of the door  5 . On the other hand, the second link arm  12  has the second rotation coupling point X 2  coupled to the door  5  in the vicinity of a front end portion  5   f  of the door  5 . Accordingly, in the vehicle  1  of the present embodiment, a vehicle door device  20 , in which the door  5  is opened and closed based on the operation of the link mechanism  15  formed by the first and second link arms  11  and  12 , is formed. 
     Specifically, as illustrated in  FIGS.  3  to  6   , in the vehicle door device  20  of the present embodiment, the first and second link arms  11  and  12  rotate around the first rotation coupling point X 1  in a counterclockwise direction at the time of the opening operation of the door  5 . Accordingly, the door  5  of the vehicle  1  supported by the first and second link arms  11  and  12  performs opening operation toward the vehicle rear side (left side in  FIGS.  3  to  6   ). 
     Furthermore in the vehicle door device  20  of the present embodiment, the first and second link arms  11  and  12  rotate around the first rotation coupling point X 1  in a clockwise direction at the time of the closing operation of the door  5  in  FIGS.  3  to  6   . Accordingly, the door  5  of the vehicle  1  supported by the first and second link arms  11  and  12  performs closing operation toward a vehicle front side (right side in  FIGS.  3  to  6   ). 
     Moreover, in the vehicle door device  20  of the present embodiment, an opening-and-closing operation trajectory R of the door  5  is defined so as to draw an arc-shaped glide trajectory Rg based on the operation of the link mechanism  15  formed by the first and second link arms  11  and  12 . That is, as illustrated in  FIG.  5   , at an intermediate position at which the first and second link arms  11  and  12  extend in a vehicle width direction (in  FIGS.  3  to  6   , in a vertical direction), a movement component in a vehicle horizontal direction increases. As illustrated in  FIGS.  3  and  4   , the first and second link arms  11  and  12  are in a state of extending in the vehicle horizontal direction (in  FIGS.  3  to  6   , in a horizontal direction) as an opening-and-closing operation position of the door  5  is closer to a fully closed position P 0 , and thus the movement component in the vehicle width direction increases. 
     Furthermore, in the vehicle door device  20  of the present embodiment, the first link arm  11  has the second rotation coupling point X 2  with respect to the door  5  at a position closer to the center of gravity G as compared with the second link arm  12 . That is, in the vehicle door device  20  of the present embodiment, the first link arm  11  is thus positioned as a main link  21  that supports a larger door load. The second link arm  12  is positioned as a sub-link  22  in which the acting door load is relatively small. 
     In the vehicle door device  20  of the present embodiment, the first link arm  11  has an outer shape larger than the second link arm  12 . Accordingly, the vehicle door device  20  of the present embodiment is configured to impart high support rigidity to the first link arm  11  positioned as the main link  21 . 
     Furthermore, the vehicle door device  20  of the present embodiment includes an actuator  25  that rotationally drives the first link arm  11  by using a motor  25   m  as a drive source. In the vehicle door device  20  of the present embodiment, the actuator  25  is provided at a base end portion of the first link arm  11 . That is, the actuator  25  of the present embodiment drives the link mechanism  15  formed by the first link arm  11  and the second link arm  12  by rotating the first link arm  11 . Accordingly, the vehicle door device  20  of the present embodiment has a configuration as a power door device  30  capable of opening and closing the door  5  based on a drive force of the actuator  25 . 
     Furthermore, as illustrated in  FIGS.  3  to  7   , the vehicle door device  20  of the present embodiment includes a door-side engagement portion  31  provided at the front end portion  5   f  of the door  5  and a vehicle body-side engagement portion  32  provided at a front edge portion  3   f  of the door opening  3 . That is, in the vehicle  1  of the present embodiment, the door-side engagement portion  31  is provided at a close-side end portion  33  located on the closing operation side of the door  5  that opens and closes the door opening  3  of the vehicle  1  based on the operation of the link mechanism  15  formed by the first and second link arms  11  and  12 . 
     Moreover, the vehicle body-side engagement portion  32  is provided at a close-side end portion  34  of the door opening  3  which the close-side end portion  33  of the door  5  comes into contact with or separates from, that is, approaches or separates from, based on the opening-and-closing operation of the door  5  moving in the vehicle horizontal direction. The vehicle door device  20  of the present embodiment is configured such that the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with each other in a state in which the door  5  is in the vicinity of the fully closed position P 0 . 
     Specifically, as illustrated in  FIGS.  8  to  9   , the vehicle door device  20  of the present embodiment includes the door-side engagement portions  31  and  31  provided at the front end portion  5   f  of the door  5  at two positions separated in the vertical direction. Moreover, the vehicle door device  20  includes the vehicle body-side engagement portions  32  and  32  provided at the front edge portion  3   f  of the door opening  3  at two positions separated in the vertical direction in a similar manner. The vehicle door device  20  of the present embodiment is configured to hold the door  5  at the fully closed position P 0  in a state in which the door-side engagement portions  31  and  31 , and the vehicle body-side engagement portions  32  and  32  are engaged with each other. 
     Furthermore, as illustrated in  FIGS.  3  to  6   , in the vehicle door device  20  of the present embodiment, the second link arm  12  positioned as the sub-link  22  is provided with a connection length variable mechanism  35  capable of changing a connection length L between the first rotation coupling point X 1  and the second rotation coupling point X 2 . 
     Moreover, the connection length variable mechanism  35  is biased in a direction of shortening the length between the first rotation coupling point X 1  and the second rotation coupling point X 2 , that is, the connection length L of the door  5  by the second link arm  12  provided with the connection length variable mechanism  35 . Accordingly, the vehicle door device  20  of the present embodiment is configured to open and close the door  5  in a state in which the connection length L is shortened by the second link arm  12 . 
     Moreover, as illustrated in  FIGS.  3 ,  4 , and  7   , in the vehicle door device  20  of the present embodiment, the opening-and-closing operation of the door  5  in a state in which the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with each other is permitted based on the operation of the connection length variable mechanism  35  provided in the second link arm  12 . That is, in the vicinity of the fully closed position P 0  at which the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with each other, the connection length L of the door  5  by the second link arm  12  changes, and thus the orientation of the door  5  supported by the link mechanism  15  formed by the first and second link arms  11  and  12  changes. Accordingly, the vehicle door device  20  of the present embodiment is configured such that the door  5  is opened and closed in a mode in which the front end portion  5   f  side of the door  5  provided with the door-side engagement portion  31  moves in the vehicle horizontal direction and a rear end portion  5   r  side moves in the vehicle width direction. 
     Specifically, for example, at the time of the closing operation of the door  5  toward the fully closed position P 0 , the door  5  is in an inclined orientation in which the rear end portion  5   r  side protrudes outward in the vehicle width direction (upper side in  FIGS.  3 ,  4 , and  7   ) as compared with the front end portion  5   f  side. Furthermore, at this time, in a state in which the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with each other, the drive force of the actuator  25  or manual operation force is applied in a direction in which the door  5  is closed. Moreover, the connection length variable mechanism  35  provided in the second link arm  12  operates based on a force for closing the door  5 , and thus the connection length L of the door  5  by the second link arm  12  is extended based on the engagement state between the door-side engagement portion  31  and the vehicle body-side engagement portion  32 . Accordingly, the vehicle door device  20  of the present embodiment is configured such that the door  5  supported by the link mechanism  15  is fully closed in a mode in which the front end portion  5   f  side draws a linear slide trajectory Rs with movement of the rear end portion  5   r  side inward in the vehicle width direction. 
     Furthermore, also at the time of the opening operation from the state in which the door  5  is at the fully closed position P 0 , in a state in which the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with each other, the drive force of the actuator  25  or manual operation force is applied in a direction in which the door  5  is opened. Moreover, the connection length variable mechanism  35  operates based on a force for opening the door  5 , and thus the connection length L of the door  5  by the second link arm  12  is shortened based on the engagement state between the door-side engagement portion  31  and the vehicle body-side engagement portion  32 . Accordingly, the vehicle door device  20  of the present embodiment is configured such that the door  5  supported by the link mechanism  15  is opened in a mode in which the front end portion  5   f  side draws a linear slide trajectory Rs with movement of the rear end portion  5   r  side outward in the vehicle width direction. 
     Door-Side Engagement Portion and Vehicle Body-Side Engagement Portion 
     Next, configurations of the door-side engagement portion  31  and the vehicle body-side engagement portion  32  in the vehicle door device  20  of the present embodiment will be described. 
     As illustrated in  FIGS.  7  and  9  to  14   , in the vehicle door device  20  of the present embodiment, the door-side engagement portion  31  includes an axial engagement portion  41  extending in the vertical direction of the vehicle  1  (in  FIGS.  7  and  12   , a direction orthogonal to the paper surface, and in  FIGS.  11  and  13   , the vertical direction) of the vehicle  1 . Furthermore, the vehicle body-side engagement portion  32  includes a guide groove  42  having a pair of side wall portions  42   a  and  42   b  facing each other in the vehicle width direction (in  FIGS.  7  and  12   , the vertical direction, and in  FIG.  13   , the horizontal direction) and extending in an opening-and-closing operation direction of the door  5 . The vehicle door device  20  of the present embodiment is configured such that the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with each other in a state in which the axial engagement portion  41  is disposed inside the guide groove  42  in a case where the door  5  is in the vicinity of the fully closed position P 0 . 
     That is, as illustrated in  FIGS.  7  and  12   , the axial engagement portion  41  of the door-side engagement portion  31  is disposed inside the guide groove  42  of the vehicle body-side engagement portion  32  in a state of being sandwiched between a pair of the side wall portions  42   a  and  42   b  facing each other in the vehicle width direction, and thus the displacement of the door  5  in the vehicle width direction is regulated. 
     Accordingly, the vehicle door device  20  of the present embodiment can stably support the door  5  even at the opening-and-closing operation position in the vicinity of the fully closed position P 0  at which the first and second link arms  11  and  12  are likely to be aligned (see  FIGS.  3  and  4   ). 
     Moreover, when the door  5  is opened and closed in this state, the axial engagement portion  41  is apparently relatively displaced along the extending direction of the guide groove  42  along with the change of the connection length L based on the operation of the connection length variable mechanism  35 . Accordingly, the opening-and-closing operation trajectory R of the door  5  changes, that is, the arc-shaped glide trajectory Rg based on the operation of the link mechanism  15  changes to the linear slide trajectory Rs. 
     More specifically, as illustrated in  FIGS.  10  to  16   , the door-side engagement portion  31  of the present embodiment includes a support bracket  44  fixed to an installation surface  43  (see  FIG.  7   ) set at the close-side end portion  33  of the door  5 . Specifically, the support bracket  44  includes a pair of support walls  45  and  45  facing each other in the vertical direction (in  FIGS.  15  and  16   , the vertical direction), and a pair of flange portions  46  and  46  provided at base end portions of the support walls  45  and  45 . In the vehicle door device  20  of the present embodiment, the support walls  45  and  45  and the flange portions  46  and  46  are integrally formed by bending a metal plate material. Furthermore, the installation surface  43  on the door  5  side to which the support bracket  44  is fixed is set at the front end portion  5   f  of the door  5  to be the close-side end portion  33  in a direction in which the door  5  is closed, that is, at a position facing the vehicle front side. 
     The support bracket  44  of the present embodiment is configured such that the pair of the flange portions  46  and  46  is fastened to the installation surface  43  on the door  5  side. 
     Furthermore, the door-side engagement portion  31  of the present embodiment includes a support shaft  47  placed between a pair of the support walls  45  and  45  constituting the support bracket  44 . In the support bracket  44  of the present embodiment, the support shaft  47  is provided at the distal end portions of the support walls  45  and  45  protruding toward the vehicle front side from the installation surface  43  on the door  5  side set at the front end portion  5   f . Moreover, the door-side engagement portion  31  includes a roller  48  axially supported to be rotatable by the support shaft  47 . Accordingly, the vehicle door device  20  of the present embodiment is configured such that the roller  48  functions as the axial engagement portion  41  of the door-side engagement portion  31  axially supported to be rotatable. 
     On the other hand, as illustrated in  FIGS.  10  to  14   , in the vehicle door device  20  of the present embodiment, the vehicle body-side engagement portion  32  includes a guide member  50  forming the guide groove  42 . The vehicle body-side engagement portion  32  of the present embodiment includes a fixing bracket  53  that fixes the guide member  50  to the installation surface  52  set at the close-side end portion  34  of the door opening  3 . 
     More specifically, in the vehicle  1  of the present embodiment, an installation surface  52  on the vehicle body  2  side to which the guide member  50  and the fixing bracket  53  are fixed is set at the front edge portion  3   f  of the door opening  3  at a position facing outward in the vehicle width direction (lower side in  FIG.  12   , left side in  FIG.  13   ). The fixing bracket  53  of the present embodiment is configured to fix the guide member  50  in a state in which a formation portion of the guide groove  42  provided in the guide member  50  is sandwiched between the fixing bracket  53  and the installation surface  52  on the vehicle body  2  side. 
     Specifically, the guide member  50  of the present embodiment has a fixing surface  54  with respect to the installation surface  52  on the vehicle body  2  side, and a first facing surface  55  facing outward in the vehicle width direction in a state in which the guide member  50  is fixed to the installation surface  52 . That is, in the guide member  50  of the present embodiment, the fixing surface  54  and the first facing surface  55  face in directions opposite to each other. Moreover, the guide member  50  includes an engagement piece  57  having a second facing surface  56  facing the first facing surface  55 . 
     The guide member  50  of the present embodiment is configured to form the guide groove  42  by using the first facing surface  55  and the second facing surface  56  as a pair of the side wall portions  42   a  and  42   b  facing each other in the vehicle width direction. 
     That is, in the guide member  50  of the present embodiment, the engagement piece  57  has a substantially plate-like outer shape protruding toward the vehicle rear side (in  FIG.  12   , from the left side to the right side) from a front end portion  50   f  of the guide member  50 , which is disposed on the vehicle front side in a state in which the guide member  50  is fixed to the installation surface  52 . Accordingly, the guide member  50  of the present embodiment is configured to form the guide groove  42  that opens in the vertical direction of the vehicle  1  and to the vehicle rear side. 
     Furthermore, the fixing bracket  53  of the present embodiment has an outer shape having a substantially cross section U-shape that covers the front end portion  50   f  of the guide member  50  forming the guide groove  42 . Specifically, the fixing bracket  53  includes a regulation wall  61  that abuts on the engagement piece  57  provided at the front end portion  50   f  of the guide member  50  from the outside in the vehicle width direction. Moreover, the fixing bracket  53  has a pair of side wall portions  62  and  62  that covers the guide member  50  in the vertical direction in a state of being continuous with the regulation wall  61 . The fixing bracket  53  has a pair of flange portions  63  and  63  provided at the base end portions of the side wall portions  62  and  62 . 
     In the fixing bracket  53  of the present embodiment, the regulation wall  61 , the side wall portions  62  and  62 , and the flange portions  63  and  63  are integrally formed by bending a metal plate material. Moreover, a pair of the flange portions  63  and  63  of the fixing bracket  53  is fastened to the installation surface  52  on the vehicle body  2  side. The fixing bracket  53  of the present embodiment is configured to sandwich the front end portion  50   f  side of the guide member  50  including the engagement piece  57 , that is, the formation portion of the guide groove  42 , between the regulation wall  61  and the installation surface  52  on the vehicle body  2  side. 
     Furthermore, as illustrated in  FIGS.  9  to  14 ,  17 , and  18  to  20   , in the vehicle door device  20   of the present embodiment, there is a difference in the shape of each of the guide members  50  constituting two vehicle body-side engagement portions  32  and  32  provided to be separated from each other in the vertical direction. 
     More specifically, the guide member  50  of the present embodiment includes a guide surface  65  continuous with the guide groove  42 . Specifically, the guide surface  65  is provided at a rear end portion  50   r  of the guide member  50  disposed on the vehicle rear side in a state in which the guide member  50  is fixed to the installation surface  52 . Moreover, the guide surface  65  is provided continuously with the first facing surface  55  of the guide member  50 , that is, one side wall portion  42   a  forming the guide groove  42  in a state of facing outward in the vehicle width direction. That is, the axial engagement portion  41  that is engaged with or disengaged from the guide groove  42  of the guide member  50  based on the opening-and-closing operation of the door  5  is guided in a direction of entering the guide groove  42  and in a direction of disengaging from the guide groove  42  by abutting on the guide surface  65 . In the vehicle door device  20  of the present embodiment, for the formation portion of the guide surface  65 , a difference in shape is set between a first guide member  71  forming an upper vehicle body-side engagement portion  32   a  and a second guide member  72  forming a lower vehicle body-side engagement portion  32   b . 
     More specifically, as illustrated in  FIGS.  12  and  14   , in the vehicle door device  20  of the present embodiment, the first guide member  71  is provided with a guide protrusion  73  that protrudes outward in the vehicle width direction in a state in which the first guide member  71  is fixed to the installation surface  52 . That is, the guide protrusion  73  is provided to protrude in a contacting-and-separating direction of the axial engagement portion  41  based on the opening-and-closing operation of the door  5 . Specifically, the guide protrusion  73  has a substantially triangular plate-like outer shape in which a protrusion amount α gradually increases from the front end portion  50   f  side toward the rear end portion  50   r  side as the guide member  50 . Accordingly, the first guide member  71  is configured such that an inclined surface  74  formed by the guide protrusion  73  and facing outward in the vehicle width direction is the guide surface  65 . 
     That is, by using the inclined surface  74  as the guide surface  65  of the guide member  50 , when the axial engagement portion  41  of the door-side engagement portion  31  abuts, an abutting angle of the axial engagement portion  41  with respect to the guide surface  65  becomes small. Accordingly, the first guide member  71  is configured to alleviate impact applied when the axial engagement portion  41  abuts against. 
     Furthermore, in the vehicle door device  20  according to the present embodiment, the inclined surface  74  of the guide protrusion  73  forming the guide surface  65  is a curved surface having a substantially constant curvature such that the inclination becomes gentler toward the guide groove  42 . Accordingly, the vehicle door device  20  of the present embodiment can suitably alleviate the impact due to the abutting, for example, even in a case where the abutting position of the axial engagement portion  41  with respect to the first guide member  71  is shifted at the time of the closing operation of the door  5  due to tolerance or the like. 
     On the other hand, as illustrated in  FIGS.  18  to  20   , the second guide member  72  forming the lower vehicle body-side engagement portion  32   b  is not provided with the guide protrusion  73  unlike described above. Accordingly, the second guide member  72  has the substantially flat guide surface  65 . 
     That is, the vehicle door device  20  of the present embodiment supports the door  5  so as to be openable and closable by the link mechanism  15  formed by the first and second link arms  11  and  12 . Therefore, at the opening-and-closing operation position in the vicinity of the fully closed position P 0  at which a distance between the first link arm  11  and the second link arm  12  is shortened and the first and second link arms  11  and  12  are linearly aligned, the orientation of the door  5  is likely to change. Accordingly, there is a possibility that a difference occurs in the engagement and disengagement orientation of the axial engagement portion  41  with respect to the guide groove  42 , in the upper vehicle body-side engagement portion  32   a  and the lower vehicle body-side engagement portion  32   b . 
     In particular, as illustrated in  FIGS.  8  and  9   , in the vehicle door device  20  of the present embodiment, the upper vehicle body-side engagement portion  32   a  is provided at a first vertical direction position Y 1  corresponding to the first link arm  11  positioned as the main link  21 . Furthermore, the lower vehicle body-side engagement portion  32   b  is provided at a second vertical direction position Y 2  corresponding to the second link arm  12  positioned as the sub-link  22 . Therefore, the difference in the engagement and disengagement orientation tends to be noticeable. 
     Specifically, in the vehicle door device  20  of the present embodiment, the first vertical direction position Y 1  corresponding to the first link arm  11  is set to a vertical direction position closer to the support position of the door  5  by the first link arm  11  as compared with the support position of the door  5  by the second link arm  12 . 
     The second vertical direction position Y 2  corresponding to the second link arm  12  is set to a vertical direction position closer to the support position of the door  5  by the second link arm  12  as compared with the support position of the door  5  by the first link arm  11 . 
     That is, as described above, the first link arm  11  has the second rotation coupling point X 2  with respect to the door  5  at a position closer to the center of gravity G of the door  5  as compared with the second link arm  12 . Moreover, the second link arm  12  is provided with a connection length variable mechanism  35  capable of changing the connection length L between the first rotation coupling point X 1  and the second rotation coupling point X 2 . Therefore, in the vehicle door device  20  of the present embodiment, the orientation change of the door  5  becomes greater toward the lower side of the door  5  supported by the second link arm  12 . Accordingly, the engagement and disengagement orientation of the axial engagement portion  41  with respect to the guide groove  42  is likely to change in the lower vehicle body-side engagement portion  32   b  as compared with the upper vehicle body-side engagement portion  32   a . 
     In view of this point, in the vehicle door device  20  of the present embodiment, for the first guide member  71  forming the upper vehicle body-side engagement portion  32   a , the engagement and disengagement trajectory of the axial engagement portion  41  with respect to the first guide member  71  is defined by the guide surface  65  formed by the guide protrusion  73 . 
     On the other hand, the second guide member  72  forming the lower vehicle body-side engagement portion  32   b  is not provided with such a guide protrusion  73 , and thus the degree of freedom of engagement and disengagement of the axial engagement portion  41  with respect to the second guide member  72  is increased. Accordingly, the vehicle door device  20  of the present embodiment has a configuration in which the axial engagement portions  41  and  41  are hardly caught when the corresponding axial engagement portions  41  and  41  are engaged with or disengaged from the first and second guide members  71  and  72 . 
     Such a phenomenon in which the first and second guide members  71  and  72  provided to be separated from each other in the vertical direction and the axial engagement portions  41  and  41  are caught is likely to occur, for example, in a case where the door  5  is opened from the fully closed position P 0 , and thus there is a possibility that the door  5  rocks. However, in the vehicle door device  20  of the present embodiment, the rocking of the door  5  due to the occurrence of such catching is suppressed. Accordingly, the vehicle door device  20  is configured to secure excellent operation feeling of the door  5 . 
     Furthermore, as illustrated in  FIGS.  12 ,  14 ,  17 , and  21   , in the vehicle door device  20   according to the present embodiment, the first guide member  71  includes a buffer member  80  having elasticity that reduces impact when the axial engagement portion  41  that relatively moves based on the opening-and-closing operation of the door  5  abuts against the first guide member  71 . 
     More specifically, in the first guide member  71 , the buffer member  80  is provided on the guide surface  65  formed by the guide protrusion  73  and the first facing surface  55  forming the side wall portion  42   a  of the guide groove  42 . That is, the buffer member  80  is provided at a position at which the axial engagement portion  41  of the door-side engagement portion  31  that relatively moves based on the opening-and-closing operation of the door  5  abuts against the first guide member  71 . Furthermore, the buffer member  80  is provided on the fixing surface  54  with respect to the installation surface  52  on the vehicle body  2  side. That is, in the vehicle door device  20  of the present embodiment, the buffer member  80  and the installation surface  52  are located on an extension line in a direction in which the axial engagement portion  41  of the door-side engagement portion  31  comes into contact with and is separated from the first guide member  71  based on the opening-and-closing operation of the door  5 . Moreover, the buffer member  80  has a plurality of protrusions  80   x  that abut on the installation surface  52  on the vehicle body  2  side. The first guide member  71  is configured to be fixed to the installation surface  52  on the vehicle body  2  side in a state in which the protrusions  80   x  are crushed. 
     More specifically, in the vehicle door device  20  of the present embodiment, the first guide member  71  includes a base member  81  having the guide groove  42  and a covering body  82  covering the base member  81 . Accordingly, in the first guide member  71 , the covering body  82  functions as the buffer member  80 . 
     Specifically, for example, a relatively hard material such as fiber-reinforced plastic is used for the base member  81 . Furthermore, for the covering body  82 , for example, an elastic material such as rubber or elastomer is used. In the vehicle door device  20  of the present embodiment, the base member  81  and the covering body  82  forming the buffer member  80  are integrally formed by insert molding. 
     Furthermore, as illustrated in  FIGS.  12 ,  14 , and  17  to  20   , the vehicle door device  20  of the present embodiment includes a coupling shaft  83  passing through the guide member  50  and the fixing bracket  53 . Specifically, in the vehicle door device  20  of the present embodiment, the rear end portion  50   r  of the guide member  50  is provided with an insertion hole  84  extending in the vertical direction in a state in which the guide member  50  is fixed to the installation surface  52  on the vehicle body  2  side. Furthermore, the side wall portions  62  and  62  of the fixing bracket  53  respectively have through holes  85  and  85  provided at positions corresponding to the insertion hole  84 . The coupling shaft  83  of the present embodiment couples the guide member  50  with the fixing bracket  53  in a state of passing through the guide member  50  and the fixing bracket  53  in the vertical direction of the vehicle  1  by being inserted into the insertion hole  84  and the through holes  85  and  85 . 
     More specifically, as illustrated in  FIGS.  12  and  20   , the coupling shaft  83  is provided to pass through the guide member  50  and the fixing bracket  53  in a state of being parallel to the installation surface  52  on the vehicle body  2  side and the regulation wall  61  of the fixing bracket  53  sandwiching the guide member  50  with the installation surface  52 . Accordingly, the coupling shaft  83  of the present embodiment extends in a direction intersecting the vehicle horizontal direction in which the guide groove  42  extends. 
     That is, when the axial engagement portion  41  of the door-side engagement portion  31  abuts against the guide member  50 , the vehicle door device  20  of the present embodiment defines a direction in which the guide member  50  is to be displaced with the coupling shaft  83  as a support shaft. Specifically, the guide member  50  tends to rotate around the coupling shaft  83  by the abutting of the axial engagement portion  41 . The vehicle door device  20  of the present embodiment is configured such that the movement of the guide member  50  is regulated by the installation surface  52  on the vehicle body  2  side or the regulation wall  61  of the fixing bracket  53  which is located in the rotation direction. 
     For example, in a case where the axial engagement portion  41  to be engaged with the guide groove  42  based on the closing operation of the door  5  abuts against the guide member  50 , the guide member  50  tends to be displaced inward in the vehicle width direction (upward in in  FIGS.  12  and  20   ) in a mode of rotating around the coupling shaft  83  (clockwise direction in  FIGS.  12  and  20   ). In this case, the front end portion  50   f  side of the guide member  50  abuts on the installation surface  52  located in the rotation direction, and thus the displacement of the guide member  50  based on the pressing force of the axial engagement portion  41  is regulated. 
     On the other hand, even in a case where the axial engagement portion  41  to be disengaged from the guide groove  42  based on the opening operation of the door  5  abuts against the guide member  50 , the guide member  50  tends to be displaced outward in the vehicle width direction (downward in  FIGS.  12  and  20   ) in a mode of rotating around the coupling shaft  83  (counterclockwise direction in  FIGS.  12  and  20   ). 
     In this case, the front end portion  50   f  side of the guide member  50  abuts on the regulation wall  61  of the fixing bracket  53  located in the rotation direction, and thus the displacement of the guide member  50  based on the pressing force of the axial engagement portion  41  is regulated. 
     Furthermore, as illustrated in  FIGS.  12 ,  14 , and  17  to  20   , the guide member  50  of the present embodiment includes a frame-shaped portion  86  disposed at a position corresponding to an entrance of the guide groove  42 . Specifically, the frame-shaped portion  86  has a substantially quadrangular frame shape that opens to the vehicle rear side. Moreover, the frame-shaped portion  86  is provided in a manner as to connect a distal end  57   a  of the engagement piece  57 , which is a formation portion of the guide groove  42 , with the rear end portion  50   r  of the guide member  50 . The guide member  50  of the present embodiment is configured such that the axial engagement portion  41  enters the guide groove  42  through the frame-shaped portion  86  as an entrance. 
     Moreover, in the vehicle door device  20  of the present embodiment, the frame-shaped portion  86  is disposed at a position to cover a rear end surface  53   x  of the fixing bracket  53 , specifically, a rear end portion (right end portion in  FIGS.  12 ,  14 , and  17  to  20   ) having a substantially cross section U-shape formed by the regulation wall  61  and the side wall portions  62  and  62 . The vehicle door device  20  of the present embodiment is configured to protect the rear end surface  53   x  of the fixing bracket  53  so as not to come into contact with, for example, a user. 
     Second Link Arm and Connection Length Variable Mechanism 
     Next, configurations of the second link arm  12  having a configuration as the sub-link  22  and the connection length variable mechanism  35  provided in the second link arm  12  will be described. 
     As illustrated in  FIGS.  22  to  25   , in the vehicle door device  20  of the present embodiment, the second link arm  12  includes a vehicle body-side link  91  having the first rotation coupling point X 1  with respect to the vehicle body  2  and a door-side link  92  having the second rotation coupling point X 2  with respect to the door  5 . Specifically, the vehicle body-side link  91  is coupled to the vehicle body  2  via a vehicle body bracket  93  provided in the vicinity of the rear edge portion  3   r  of the door opening  3 . Furthermore, the door-side link  92  is coupled to the door  5  via a door bracket  94  fixed to an inner side surface  5   s  of the door  5 . Moreover, the second link arm  12  has a configuration in which the vehicle body-side link  91  and the door-side link  92  are rotatably coupled. In the vehicle door device  20  of the present embodiment, a joint link mechanism  100  formed by this configuration forms the connection length variable mechanism  35 . 
     More specifically, as illustrated in  FIGS.  22  and  23   , the door-side link  92  of the present embodiment has a configuration as a so-called mini arm having a short axial length in comparison with the vehicle body-side link  91 . Furthermore, the vehicle body-side link  91  has a vehicle body-side coupling portion  101  with respect to the vehicle body  2  on one end side in the longitudinal direction of the vehicle body-side link  91 . Moreover, the door-side link  92  also has a door-side coupling portion  102  with respect to the door  5  on one end side in the longitudinal direction of the door-side link  92 . The vehicle body-side link  91  and the door-side link  92  respectively have intermediate coupling portions  103  and  104  coupled to each other on the other end side in the longitudinal direction. 
     That is, in the vehicle door device  20  of the present embodiment, the intermediate coupling portions  103  and  104  form an intermediate coupling point X 3  of the joint link mechanism  100  provided in the second link arm  12 . Furthermore, in the second link arm  12 , the vehicle body-side link  91  and the door-side link  92  form a triangle with the intermediate coupling point X 3  as a vertex. Accordingly, the vehicle body-side link  91  and the door-side link  92  relatively rotate, and thus the length of the straight line connecting the first rotation coupling point X 1  with the second rotation coupling point X 2 , which forms the base of the triangle, that is, the connection length L changes. 
     Specifically, as illustrated in  FIGS.  22 ,  23 ,  26 , and  27   , in the present embodiment, the intermediate coupling point X 3  between the vehicle body-side link  91  and the door-side link  92  is disposed at a position closer to the inner side surface  5   s  of the door  5  than the second rotation coupling point X 2  with respect to the door  5 . A recess  105  for avoiding contact with the intermediate coupling portions  103  and  104  of the vehicle body-side link  91  and the door-side link  92  forming the intermediate coupling point X 3  is formed on the inner side surface  5   s  of the door  5  of the present embodiment. Accordingly, the vehicle door device  20  of the present embodiment is configured such that the connection length L between the vehicle body  2  and the door  5  by the second link arm  12  changes in a mode in which the intermediate coupling point X 3  apparently rotates around the second rotation coupling point X 2  based on the opening-and-closing operation of the door  5 . 
     More specifically, as illustrated in  FIGS.  26  to  29   , the vehicle body-side link  91  of the present embodiment has an elongated substantially axial outer shape. Moreover, the vehicle body-side link  91  has a crank-shaped bent portion  106 . Accordingly, the vehicle door device  20  of the present embodiment is configured to avoid interference of the second link arm  12  and the rear edge portion  3   r  of the door opening  3  and secure a larger door opening amount when the door  5  is fully opened. 
     Furthermore, as illustrated in  FIGS.  28  to  30   , in the vehicle door device  20  of the present embodiment, the door-side link  92  has a pair of clamping portions  107  and  107  rotatably coupled to an intermediate coupling portion  103  in a state in which the intermediate coupling portion  103  of the vehicle body-side link  91  is interposed between the clamping portions  107  and  107 . 
     Specifically, each of the clamping portions  107  and  107  has the door-side coupling portion  102  with respect to the door  5  on one end side in the longitudinal direction of the clamping portion  107 , and has an intermediate coupling portion  104  with respect to the door-side link  92  on the other end side in the longitudinal direction of the clamping portion  107 . Furthermore, the door-side link  92  of the present embodiment has a connection portion  108  at the intermediate coupling portion  104  by bending a metal plate material, and the clamping portions  107  and  107  are integrally formed. Moreover, in the vehicle door device  20  of the present embodiment, the intermediate coupling portion  103  of the vehicle body-side link  91  also has a substantially flat shape. Accordingly, the second link arm  12  has a configuration in which the intermediate coupling portion  103  of the vehicle body-side link  91  is interposed between the intermediate coupling portions  104  and  104  of the door-side link  92  formed by a pair of the clamping portions  107  and  107  having a bent plate shape. 
     Furthermore, in the door-side link  92  of the present embodiment, each of the clamping portions  107  and  107  has a bent plate-like cross-sectional shape in which the other end sides forming the door-side coupling portions  102  in the longitudinal direction are separated from each other. Accordingly, the door-side link  92  of the present embodiment is configured such that the clamping portions  107  and  107  are rotatably coupled to the door  5  at positions separated in the vertical direction. 
     More specifically, in the vehicle door device  20  of the present embodiment, the door bracket  94  fixed to the inner side surface  5   s  of the door  5  includes a pair of coupling walls  110  and  110  having a substantially flat shape and facing each other in the vertical direction. In the door-side link  92 , the vertically separated door-side coupling portions  102  and  102  formed by a pair of the clamping portions  107  and  107  are respectively coupled to the coupling walls  110  and  110 . 
     Furthermore, the vehicle door device  20  of the present embodiment includes a pair of support shafts  112  and  112  provided coaxially with the second rotation coupling point X 2  formed by the door-side coupling portions  102  and  102  of the door-side link  92  and the coupling walls  110  and  110  of the door bracket  94 . In the door bracket  94  of the present embodiment, one side of each of the support shafts  112  and  112  is erected in a state of protruding upward from each of the coupling walls  110  above the support shafts  112  and  112 . Furthermore, the other side of each of the support shafts  112  and  112  is erected in a state of protruding downward from the coupling wall  110  below the support shaft. Moreover, torsion coil springs  113  and  113  are respectively fitted to the support shafts  112  and  112 . 
     The vehicle door device  20  of the present embodiment is configured such that the door-side link  92  is rotationally biased by using the torsion coil springs  113  and  113  as a biasing member  115 . 
     That is, as illustrated in  FIGS.  31  and  32   , the torsion coil springs  113  and  113  generates a biasing force F for relatively rotating the vehicle body-side link  91  and the door-side link  92  in a direction in which the connection length L between the first and second rotation coupling points X 1  and X 2  is shortened. Furthermore, accordingly, in the second link arm  12 , the connection length L between the first and second rotation coupling points X 1  and X 2  becomes shorter than the fully closed position P 0  based on the opening operation of the door  5  (see  FIGS.  22  and  23   ). Accordingly, the vehicle door device  20  of the present embodiment is configured to open and close the door  5  in a state in which the connection length L between the first and second rotation coupling points X 1  and X 2  in the second link arm  12  is shortened (see  FIGS.  3  to  6   ). 
     As illustrated in  FIGS.  28  and  30  to  32   , in the vehicle door device  20  of the present embodiment, the door bracket  94  is provided with a stopper  116 . Specifically, when the door  5  performs the opening operation from the fully closed position P 0 , apparently the intermediate coupling point X 3  between the vehicle body-side link  91  and the door-side link  92  rotates around the second rotation coupling point X 2 , and thus the stopper  116  abuts against the connection portion  108  of the door-side link  92 . Accordingly, the vehicle door device  20  of the present embodiment is configured to secure a stable opening-and-closing operation orientation of the door  5  supported by the second link arm  12 . 
     Furthermore, as illustrated in  FIGS.  31  and  32   , the vehicle door device  20  of the present embodiment is configured such that the biasing force F of the biasing member  115  changes based on the relative rotation of the vehicle body-side link  91  and door-side link  92  constituting the joint link mechanism  100 . Specifically, when the door  5  performs the opening operation from the fully closed position P 0 , a component force F′ of the biasing force F in a connection length direction in the second link arm  12  becomes stronger than that at the fully closed position P 0 . Accordingly, the vehicle door device  20  of the present embodiment is configured to secure good fitting of the door  5  by reducing the component force F′ of the biasing force F in the connection length direction in a case where the door  5  is in the fully closed state. 
     More specifically, as illustrated in  FIGS.  28  to  34   , the vehicle door device  20  of the present embodiment includes an engagement protrusion portion  121  provided on the vehicle body-side link  91 , and a cam member  123  having a cam groove  122  with which the engagement protrusion portion  121  engages and provided on the door  5 . 
     Specifically, in the vehicle door device  20  of the present embodiment, the vehicle body-side link  91  includes a support shaft  124  provided in the vicinity of the intermediate coupling portion  103  with the door-side link  92  and protruding upward, and a roller  125  axially supported to be rotatable by the support shaft  124 . Accordingly, the vehicle door device  20  of the present embodiment is configured such that the roller  125  functions as the engagement protrusion portion  121 . 
     Furthermore, in the vehicle door device  20  of the present embodiment, the cam member  123  is provided integrally with a coupling wall  110   a  on the upper side of the door bracket  94  to which the door-side link  92  is coupled. That is, the cam member  123  has a substantially flat shape. Moreover, the cam member  123  is disposed above the vehicle body-side link  91  and the door-side link  92  so as to cover the upper side of the intermediate coupling portions  103  and  104 . The cam member  123  of the present embodiment includes the cam groove  122  provided so as to vertically penetrate the cam member  123 . 
     Specifically, the cam groove  122  of the present embodiment has an arc-shaped portion  126  protruding inward in the vehicle width direction (lower side in  FIGS.  31  to  34   ) in a state in which the cam member  123  formed integrally with the door bracket  94  is fixed to the inner side surface  5   s  of the door  5 . Furthermore, the cam groove  122  has a linear portion  127  extending toward the vehicle rear side continuously with the arc-shaped portion  126 . Moreover, in the vehicle door device  20  of the present embodiment, the roller  125  to be the engagement protrusion portion  121  is disposed inside the cam groove  122 . The vehicle door device  20  of the present embodiment is configured such that the roller  125  moves inside the cam groove  122  in a state of being in sliding contact with the cam groove  122  based on the opening-and-closing operation of the door  5 . 
     That is, when the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with each other, the roller  125  moves in the linear portion  127  of the cam groove  122  at the opening-and-closing operation position in the vicinity of the fully closed position P 0  at which the front end portion  5   f  of the door  5  draws the linear slide trajectory Rs. Furthermore, when the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are disengaged from each other, the roller  125  moves in the arc-shaped portion  126  of the cam groove  122  in a range in which the front end portion  5   f  of the door  5  draws the arc-shaped glide trajectory Rg and performs the opening-and-closing operation. Accordingly, the vehicle door device  20  of the present embodiment is configured such that the opening-and-closing operation trajectory R of the door  5  is defined. 
     Specifically, in the vehicle door device  20  of the present embodiment, the relative rotation between the vehicle body-side link  91  and the door-side link  92  is regulated according to the engagement position of the roller  125  in the cam groove  122 . That is, the connection length L between the first rotation coupling point X 1  and the second rotation coupling point X 2  based on the operation of the connection length variable mechanism  35  formed by the vehicle body-side link  91  and the door-side link  92  is defined. Furthermore, similarly, the rotation of the door  5  around the second rotation coupling point X 2  formed by the door-side link  92  is regulated based on the engagement position of the roller  125  in the cam groove  122 . 
     Accordingly, the vehicle door device  20  of the present embodiment is configured such that the opening-and-closing operation trajectory R of the door  5  is defined. 
     Furthermore, as illustrated in  FIG.  35   , the vehicle door device  20  of the present embodiment includes a buffer member  131  interposed between the vehicle body  2  and the second link arm  12  as a stopper in a case where the door  5  is at a fully opened position P 1 . 
     More specifically, in the vehicle door device  20  of the present embodiment, the buffer member  131  is formed using a relatively soft elastic member such as a rubber material or an elastomer. Furthermore, the buffer member  131  is provided on the vehicle body-side link  91  having the first rotation coupling point X 1  with respect to the vehicle body  2 . Specifically, the buffer member  131  is fixed to the crank-shaped bent portion  106  provided on the vehicle body-side link  91 . Accordingly, the second link arm  12  rotates around the first rotation coupling point X 1 , and the door  5  reaches the fully opened position P 1 , and thus the buffer member  131  of the present embodiment is sandwiched between the vehicle body-side link  91  and the rear edge portion  3   r  of the door opening  3 . 
     That is, in the vehicle door device  20  of the present embodiment, the buffer member  131  supports the door  5  that has reached the fully opened position P 1  on the vehicle body  2  in a state of being crushed between the vehicle body-side link  91  and the rear edge portion  3   r  of the door opening  3 . Accordingly, the vehicle door device  20  of the present embodiment is configured such that rocking of the door  5  is suppressed and stably held at the fully opened position P 1 . 
     Furthermore, as illustrated in  FIGS.  29 ,  35 , and  36   , in the vehicle door device  20  of the present embodiment, the vehicle body-side coupling portion  101  provided on the vehicle body-side link  91  has a substantially flat shape. Moreover, the vehicle body bracket  93  that supports the vehicle body-side link  91  on the vehicle body  2  has a pair of coupling walls  132  and  132  disposed with the vehicle body-side coupling portion  101  interposed therebetween in the vertical direction. In the vehicle door device  20  of the present embodiment, the rotation shaft of the vehicle body-side link  91  with respect to the vehicle body  2  is formed around a support shaft  133  vertically passing through the vehicle body-side coupling portion  101  of the vehicle body-side link  91  and the coupling walls  132  and  132  of the vehicle body bracket  93 . That is, the first rotation coupling point X 1  is formed with the support shaft  133  as the support shaft N 2   a  of the second link arm  12  with respect to the door  5 . 
     More specifically, in the vehicle door device  20  of the present embodiment, the vehicle body bracket  93  includes the coupling walls  132  and  132  and is formed by bending a metal plate material. Furthermore, through holes  134  and  134  and a through hole  135  are respectively provided on the coupling walls  132  and  132  of the vehicle body bracket  93  and the vehicle body-side coupling portion  101  of the vehicle body-side link  91 , the through holes  134  and  134 , and through hole  135  penetrating, in the thickness direction, the coupling walls  132  and  132  of the vehicle body bracket  93  and the vehicle body-side coupling portion  101  of the vehicle body-side link  91 , which have the substantially flat plate shape. The vehicle door device  20  of the present embodiment includes a bush  138  as a cylindrical buffer member  137  fitted in the through hole  135  of the vehicle body-side coupling portion  101  having the configuration as a plate-shaped coupling portion  136 . 
     Specifically, the bush  138  is formed using a relatively soft elastic member such as a rubber material or an elastomer. Furthermore, the support shaft  133  is inserted into the through hole  135  provided on the vehicle body-side coupling portion  101  of the vehicle body-side link  91  via the bush  138 . The axial opposite ends of the support shaft  133  are inserted into the through holes  134  and  134  provided on the coupling walls  132  and  132  of the vehicle body bracket  93 , and thus the support shaft  133  is supported by the vehicle body bracket  93  in a state of extending in the vertical direction. 
     That is, in the vehicle door device  20  of the present embodiment, the vehicle body-side link  91  rotates around the support shaft  133 , and thus the first rotation coupling point X 1  of the second link arm  12  with respect to the vehicle body  2  is formed. In the vehicle door device  20  of the present embodiment, a gap is set between the vehicle body-side coupling portion  101  of the vehicle body-side link  91  and the coupling walls  132  and  132  of the vehicle body bracket  93  sandwiching the vehicle body-side coupling portion  101  in the vertical direction. Moreover, in the vehicle door device  20  of the present embodiment, the bush  138  as the cylindrical buffer member  137  is elastically deformed, and thus the vehicle body-side coupling portion  101  having the configuration as the plate-shaped coupling portion  136  is allowed to be displaced. That is, the vertical displacement of the second link arm  12  including tilting with respect to the support shaft N 2   a  is allowed. Accordingly, the vehicle door device  20  of the present embodiment is configured to increase the degree of freedom of coupling the second link arm  12  with respect to the vehicle body  2 . 
     As illustrated in  FIG.  30   , in the vehicle door device  20  of the present embodiment, the intermediate coupling point X 3  formed by the intermediate coupling portions  103  and  104  of the vehicle body-side link  91  and the door-side link  92  also has a similar coupling structure. 
     That is, the intermediate coupling portion  103  of the vehicle body-side link  91  and the intermediate coupling portions  104  and  104  of the door-side link  92 , which are disposed so as to sandwich the intermediate coupling portion  103  in the vertical direction, also have a substantially flat plate shape. Furthermore, the intermediate coupling portions  103 ,  104 , and  104  are respectively provided with a through hole  143  and through holes  144  and  144  penetrating the intermediate coupling portions  103 ,  104 , and  104  in the thickness direction, which have the substantially flat plate shape. Similarly to the vehicle body-side coupling portion  101  of the vehicle body-side link  91 , the bush  138  as the cylindrical buffer member  137  is fitted into the through hole  143  provided on the intermediate coupling portion  103  of the vehicle body-side link  91  having the configuration as the plate-shaped coupling portion  136 . 
     Furthermore, the vehicle door device  20  of the present embodiment has a support shaft  149  inserted into the through hole  143  provided on the intermediate coupling portion  103  of the vehicle body-side link  91  via the bush  138 . Moreover, the axial opposite side portions of the support shaft  149  are inserted into the through holes  144  and  144  provided in the intermediate coupling portions  104  and  104  of the door-side link  92 . Accordingly, the vehicle door device  20  of the present embodiment is configured such that the vehicle body-side link  91  and door-side link  92  constituting the second link arm  12  relatively rotate around the support shaft  149 , and thus the intermediate coupling point X 3  is formed. 
     Moreover, also for the intermediate coupling point X 3 , the bush  138  as the cylindrical buffer member  137  is elastically deformed, and thus tilting of the intermediate coupling portion  103  of the vehicle body-side link  91  with respect to the support shaft  149  is allowed, the intermediate coupling portion  103  having the configuration as the plate-shaped coupling portion  136 . Accordingly, in the vehicle door device  20  of the present embodiment, the degree of freedom of coupling between the vehicle body-side link  91  and the door-side link  92  at the intermediate coupling point X 3  is increased. 
     First Link Arm 
     Next, a configuration of the first link arm  11  having a configuration as the main link  21  will be described. 
     As illustrated in  FIG.  24    and  FIGS.  37  to  39   , in the vehicle door device  20  of the present embodiment, the first link arm  11  includes a pair of pipe frames  151  and  151  disposed side by side in the vertical direction. The first link arm  11  includes a base end bracket  153  coupling the base end portions of the pipe frames  151  and  151  and a distal end bracket  154  coupling the distal end portions of the pipe frames  151  and  151 . 
     Furthermore, the vehicle door device  20  of the present embodiment includes a vehicle body bracket  155  to which the base end bracket  153  constituting the first link arm  11  is rotatably coupled in a state of being fixed in the vicinity of the rear edge portion  3   r  of the door opening  3 . Moreover, similarly, the vehicle door device  20  includes a door bracket  156  to which the distal end bracket  154  constituting the first link arm  11  is rotatably coupled in a state of being fixed to the inner side surface  5   s  of the door  5 . Accordingly, in the vehicle door device  20  of the present embodiment, the first and second rotation coupling points X 1  and X 2  in the first link arm  11  are formed. 
     More specifically, in the vehicle door device  20  of the present embodiment, the base end bracket  153  forming a base end portion  11   a  of the first link arm  11  includes a base portion  160  that couples a pair of the pipe frames  151  and  151  in a state of extending in the vertical direction. Furthermore, the base end bracket  153  includes a pair of coupling portions  161  and  161  extending in a direction opposite to the extending direction of the pipe frames  151  and  151  coupled to the base portion  160  from the upper end and lower end of the base portion  160 . Moreover, the vehicle body bracket  155  is provided with a pair of coupling portions  162  and  162  to which the coupling portions  161  and  161  are independently coupled. In the vehicle door device  20  of the present embodiment, the coupling portions  161  and  161  of the base end bracket  153  and the coupling portions  162  and  162  of the vehicle body bracket  155  are independently coupled to each other so as to be rotatable around the support shafts  163  and  163  extending in the vertical direction. 
     That is, accordingly, in the vehicle door device  20  of the present embodiment, the base end portion  11   a  of the first link arm  11  is rotatably coupled to the vehicle body  2  at two positions separated in the vertical direction. Accordingly, the first rotation coupling point X 1  is formed with the support shafts  163  and  163  as the support shaft N 1   a  of the first link arm  11  with respect to the vehicle body  2 . 
     In the vehicle door device  20  of the present embodiment, each of the support shafts  163  and  163  is also provided to pass through the bush  138  as the cylindrical buffer member  137  fitted into the each of the coupling portions  161  and  161  of the base end bracket  153  having a substantially flat plate shape. That is, for the first rotation coupling point X 1  in the first link arm  11 , similarly to the case of the second link arm  12 , the bush  138  is elastically deformed, and thus, the displacement of each of the coupling portions  161  and  161  of the base end bracket  153  is allowed as the plate-shaped coupling portion  136   d . Accordingly, the vehicle door device  20  of the present embodiment is configured to increase the degree of freedom of coupling the first link arm  11  with respect to the vehicle body  2  by allowing the displacement of the second link arm  12  in the vertical direction, which includes tilting with respect to the support shaft N 1   a . 
     On the other hand, in the vehicle door device  20  of the present embodiment, the distal end bracket  154  forming a distal end portion  11   b  of the first link arm  11  has a cover shape covering a distal end side of a pair of the pipe frames  151  and  151 . Specifically, the distal end bracket  154  includes a cover portion  164  that covers the distal end sides of the pipe frames  151  and  151  in a state of being disposed on the inner side than the pipe frames  151  and  151  in the vehicle width direction. In the vehicle door device  20 , for example, each of the pipe frames  151  and  151  is fixed to the back surface of the cover portion  164  by welding or the like. Accordingly, the vehicle door device  20  of the present embodiment is configured such that the distal end portions of the pipe frames  151  and  151  constituting the first link arms  11  are coupled by the distal end bracket  154 . 
     Furthermore, in the vehicle door device  20  of the present embodiment, the distal end bracket  154  includes a pair of coupling flanges  167  and  167  facing each other in the vertical direction. Moreover, the door bracket  156  fixed to the inner side surface  5   s  of the door  5  also includes a pair of coupling flanges  168  and  168  facing each other in the vertical direction. The coupling flanges  167  and  167  of the distal end bracket  154  and the coupling flanges  168  and  168  of the door bracket  156  are rotatably coupled to each other, and thus the second rotation coupling point X 2  in the first link arm  11  is formed. 
     Specifically, the vehicle door device  20  of the present embodiment includes a support shaft  170  that vertically passes through the coupling flanges  167  and  167  of the distal end bracket  154  and the coupling flanges  168  and  168  of the door bracket  156 . The coupling flanges  167  and  167  of the distal end bracket  154  and the coupling flanges  168  and  168  of the door bracket  156  relatively rotate around the support shaft  170 . 
     That is, in the vehicle door device  20  of the present embodiment, the coupling flanges  167  and  167  and the coupling flanges  168  and  168  are respectively used as a first rotation coupling portion  171  and a second rotation coupling portion  172 , and the second rotation coupling point X 2  is formed. Moreover, the vehicle door device  20  of the present embodiment includes a friction member  175  interposed between the first and second rotation coupling portions  171  and  172  and in sliding contact with the first and second rotation coupling portions  171  and  172 . Specifically, the friction member  175  is formed using a resin material having relatively large frictional resistance, such as nylon. Moreover, the friction member  175  is subjected to surface treatment for increasing the frictional resistance. Accordingly, sliding resistance is applied when the first and second rotation coupling portions  171  and  172  forming the second rotation coupling point X 2  relatively rotate. 
     More specifically, in the vehicle door device  20  of the present embodiment, each of the coupling flanges  168  and  168  of the door bracket  156  is disposed inside each of the coupling flanges  167  and  167  of the distal end bracket  154  separated from each other in the vertical direction. 
     That is, as illustrated in  FIG.  40   , for a coupling flange  167   a  and coupling flange  168   a  on the lower side, the coupling flange  168   a  of the door bracket  156  is disposed above the coupling flange  167   a  of the distal end bracket  154 . Furthermore, the friction member  175  of the present embodiment has an annular plate shape fitted to the support shaft  170 . In the vehicle door device  20  of the present embodiment, the friction member  175  is provided in a state of being sandwiched between the coupling flange  167   a  of the distal end bracket  154  and the coupling flange  168   a  of the door bracket  156 , which overlap each other in the vertical direction. 
     That is, in the vehicle door device  20  of the present embodiment, the load of the door  5  is applied to the friction member  175  via the coupling flange  168   a  of the door bracket  156  located above the friction member  175 . Furthermore, accordingly, a frictional force is generated between the friction member  175  and the coupling flange  167   a  of the distal end bracket  154  and the coupling flange  168   a  of the door bracket  156 , which sandwich the friction member  175 . Moreover, the coupling flange  167   a  of the distal end bracket  154  and the coupling flange  168   a  of the door bracket  156  relatively rotate around the support shaft  170 , and thus the sliding resistance is applied. Accordingly, the vehicle door device  20  of the present embodiment is configured to attenuate rocking and vibration generated in the door  5  by increasing the operation resistance of the door  5  rotating around the second rotation coupling point X 2  formed by the first and second rotation coupling portions  171  and  172 . 
     Actuator 
     Next, a configuration of the actuator  25  in the vehicle door device  20  of the present embodiment will be described. 
     As described above, in the vehicle door device  20  of the present embodiment, the actuator  25  that generates the drive force for opening and closing the door  5  is provided at the base end portion  11   a  of the first link arm  11 . Moreover, the actuator  25  rotationally drives the first link arm  11  by using the motor  25   m  as a drive source. Accordingly, the vehicle door device  20  is configured to open and close the door  5  supported by the vehicle body  2  via the link mechanism  15  based on the operation of the link mechanism  15  formed by the first link arm  11  and the second link arm  12  (see  FIGS.  3  to  6   ). 
     More specifically, as illustrated in  FIGS.  37  to  39    and  FIG.  41   , in the vehicle door device  20  of the present embodiment, the actuator  25  is disposed at a formation portion  180  of the first rotation coupling point X 1  of the first link arm  11  with respect to the vehicle body  2 . 
     Specifically, as described above, the base end portion  11   a  of the first link arm  11  is rotatably coupled to the vehicle body bracket  155  provided in the vehicle body  2  at two positions separated in the vertical direction. The actuator  25  of the present embodiment is disposed at a vertical direction position between the coupling portions  161  and  161  on the first link arm  11  side and the coupling portions  162  and  162  on the vehicle body bracket  155  side, which are rotatably coupled to each other at two positions separated from each other in the vertical direction. 
     That is, in the vehicle door device  20  of the present embodiment, the base end bracket  153  having a substantially U-shape forms the base end portion  11   a  of the first link arm  11 . Moreover, the vehicle body bracket  155  also has a substantially U-shaped portion including the coupling portions  162  and  162  separated from each other in the vertical direction. The vehicle door device  20  of the present embodiment is configured such that the actuator  25  is disposed in the formation portion  180  of the first rotation coupling point X 1  formed by coupling the two U-shaped members in a relatively rotatable manner. 
     In other words, in the vehicle door device  20  of the present embodiment, the first rotation coupling point X 1  of the first link arm  11  with respect to the vehicle body  2  has an upper coupling point  181  and a lower coupling point  182  which are provided to be separated from each other in the vertical direction. The actuator  25  is provided at a position between the upper coupling point  181  and the lower coupling point  182  in the formation portion  180  of the first rotation coupling point X 1 . 
     More specifically, in the actuator  25  of the present embodiment, the motor  25   m  serving as a drive source has a configuration as a geared motor  183  with a reduction gear. Furthermore, the actuator  25  of the present embodiment includes a speed reduction mechanism  184  that further decreases the rotation of the motor  25   m . Moreover, the vehicle door device  20  of the present embodiment includes a sector gear  185  that protrudes from the base portion  160  of the base end bracket  153  forming the base end portion  11   a  of the first link arm  11  and is disposed at a position between the coupling portions  161  and  161 . In the vehicle door device  20  of the present embodiment, a pinion gear  186  of the speed reduction mechanism  184  meshes with the sector gear  185 , and thus the drive force of the actuator  25  is transmitted to the first link arm  11 . 
     The actuator  25  of the present embodiment is fixed to the vehicle body bracket  155  by using a fixing bracket  187 . Furthermore, the vehicle door device  20  of the present embodiment includes a cover member  188  having a substantially cross section U-shape. Moreover, in the vehicle door device  20  of the present embodiment, in the cover member  188 , flange portions  189  and  189  provided at opposite ends of a cover portion  188   x  having the substantially cross section U-shape are fixed to the coupling portions  162  and  162  on the vehicle body bracket  155  side provided to be separated from each other in the vertical direction. Accordingly, the vehicle door device  20  of the present embodiment is configured such that the cover member  188  covers the side of the actuator  25  disposed in the formation portion  180  of the first rotation coupling point X 1 . 
     Next, an action of the present embodiment will be described. 
     That is, in the vehicle door device  20  of the present embodiment, the axial engagement portion  41  abuts against the first guide member  71  via the elastic buffer member  80 , and thus the impact at the time of the abutment is alleviated. When the axial engagement portion  41  abuts against the first guide member  71 , the buffer member  80  interposed between the fixing surface  54   and the installation surface  52  is elastically deformed, and thus the impact due to the abutment is alleviated. 
     Next, effects of the present embodiment will be described. 
     The vehicle door device  20  includes the first and second link arms  11  and  12  that include the first rotation coupling point X 1  with respect to the vehicle body  2 , and the second rotation coupling point X 2  with respect to the door  5  of the vehicle  1 . Furthermore, the vehicle door device  20  includes the door-side engagement portion  31  provided at the close-side end portion  33  of the door  5  that opens and closes the door opening  3  of the vehicle  1  based on the operation of the link mechanism  15  formed by the first and second link arms  11  and  12 . Moreover, the vehicle door device  20  includes the vehicle body-side engagement portion  32  provided at the close-side end portion  34  of the door opening  3  which the close-side end portion  33  of the door  5  comes into contact with or separates from, that is, approaches or separates from, based on the opening-and-closing operation of the door  5 . The door-side engagement portion  31  includes the axial engagement portion  41  extending in the vertical direction of the vehicle  1 , and the vehicle body-side engagement portion  32  includes the guide groove  42  having a pair of the side wall portions  42   a  and  42   b  facing each other in the vehicle width direction and extending in the opening-and-closing operation direction of the door  5 . 
     At the opening-and-closing operation position in the vicinity of the fully closed position P 0  of the door  5  at which the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with each other, the axial engagement portion  41  is disposed inside the guide groove  42 . 
     According to the above-described configuration, the axial engagement portion  41  is disposed inside the guide groove  42 , and thus the displacement of the door  5  in the vehicle width direction is regulated. Accordingly, even at the opening-and-closing operation position in the vicinity of the fully closed position P 0  at which the first and second link arms  11  and  12  are brought closer to each other and are linearly aligned, the door  5  can be stably supported. 
     (2) Furthermore, the configuration in which the door-side engagement portion  31  includes the axial engagement portion  41  is adopted, and thus the door-side engagement portion  31  is less likely to interfere with the user when the user gets on and off the vehicle  1 . Moreover, when the guide groove  42  is provided on the vehicle body-side engagement portion  32  side, for example, clothes of the user are less likely to be caught by the guide groove  42 . Therefore, convenience can be improved. 
     (3) The vehicle door device  20  includes the guide member  50  forming the guide groove  42 . The guide member  50  includes the buffer member  80  having elasticity that reduces the impact when the axial engagement portion  41  that relatively moves based on the opening-and-closing operation of the door  5  abuts against the guide member  50 . 
     According to the above-described configuration, when the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with or disengaged from each other based on the opening-and-closing operation of the door  5 , it is possible to effectively alleviate the impact acting on the guide member  50  due to the abutment of the axial engagement portion  41 . Therefore, it is possible to suppress the generation of noise or vibration and secure a high operation feeling. 
     (4) The buffer member  80  is provided at a position at which the axial engagement portion  41  of the door-side engagement portion  31  that relatively moves based on the opening-and-closing operation of the door  5  abuts against the first guide member  71 . 
     According to the above configuration, the axial engagement portion  41  abuts against the guide member  50  via the elastic buffer member  80 , and thus the impact acting on the guide member  50  due to the abutment of the axial engagement portion  41  can be effectively alleviated. 
     (5) The guide member  50  includes the guide surface  65  continuous with the guide groove  42 . The buffer member  80  is provided on the guide surface  65 . 
     That is, the axial engagement portion  41  that is engaged with or disengaged from the guide groove  42  of the guide member  50  based on the opening-and-closing operation of the door  5  is guided in a direction of entering the guide groove  42  and in a direction of disengaging from the guide groove  42  by abutting on the guide surface  65 . According to the above-described configuration, it is possible to effectively alleviate the impact acting on the guide member  50  due to the abutment of the axial engagement portion  41 . 
     (6) The buffer member  80  is provided on the fixing surface  54  of the guide member  50  with respect to the installation surface  52  on the vehicle body  2  side. 
     According to the above configuration, the buffer member  80  interposed between the fixing surface  54  and the installation surface  52  is elastically deformed, and thus the impact acting on the guide member  50  due to the abutment of the axial engagement portion  41  can be effectively alleviated. 
     (7) The buffer member  80  has a plurality of the protrusions  80   x  that are crushed by the installation surface  52  when the guide member  50  is fixed to the installation surface  52 . 
     According to the above-described configuration, since the crushed protrusions  80   x  reduce backlash, rattling of the guide member  50  fixed to the installation surface  52  can be suppressed. Therefore, a high operation feeling can be secured. 
     (8) The buffer member  80  and the installation surface  52  are located on an extension line in a direction in which the axial engagement portion  41  comes into contact with and separates from the guide member  50  based on the opening-and-closing operation of the door  5 . Therefore, it is possible to effectively alleviate the impact acting on the guide member  50  due to the abutment of the axial engagement portion  41 . 
     (9) The guide member  50  includes a base member  81  having the guide groove  42  and a covering body  82  forming the buffer member  80  in a state of covering the base member  81 . 
     According to the above-described configuration, the buffer member  80  can be appropriately disposed at a position at which the impact when the axial engagement portion  41  abuts against the guide member  50  can be alleviated. Moreover, for example, the covering body  82  to be the buffer member  80  can be integrally molded with the base member  81  by using two-color molding. Therefore, the manufacturing process of the guide member  50  can be facilitated. 
     (10) The vehicle door device  20  includes, as the guide member  50 , the first and second guide members  71  and  72  that are disposed to be separated from each other in the vertical direction. The first guide member  71  has the guide protrusion  73  protruding in the contacting-and-separating direction of the axial engagement portion  41  based on the opening-and-closing operation of the door  5 , and the guide protrusion  73  forms the guide surface  65 . The second guide member  72  does not have the guide protrusion  73 . 
     According to the above-described configuration, in the first guide member  71 , the engagement and disengagement trajectory of the axial engagement portion  41  with respect to the first guide member  71  is defined by the guide surface  65  formed by the guide protrusion  73 . Furthermore, in the second guide member  72 , the guide protrusion  73  is not provided, and thus the degree of freedom of engagement and disengagement of the axial engagement portion  41  with respect to the second guide member  72  is increased. Accordingly, the axial engagement portions  41  and  41  are hardly caught by the corresponding first and second guide members  71  and  72  when the corresponding axial engagement portions  41  and  41  are engaged with or disengaged from the first and second guide members  71  and  72 . As a result, the rocking of the door  5  caused by the occurrence of the catching can be suppressed, and good operation feeling can be secured. 
     (11) The first link arm  11  has the second rotation coupling point X 2  connected to the door  5  at a position closer to the center of gravity G of the door  5  as compared with the second link arm  12 . The first guide member  71  is provided at the first vertical direction position Y 1  corresponding to the first link arm  11 . 
     That is, near the support position by the first link arm  11  configured as described above, the orientation change of the door  5  tends to be small, that is, the engagement and disengagement orientation of the axial engagement portion  41  with respect to the guide groove  42  tends to hardly change. Therefore, by providing the first guide member  71  having the guide protrusion  73  at the first vertical direction position Y 1  corresponding to the first link arm  11 , it is possible to define the engagement and disengagement trajectory while preventing the axial engagement portion  41  from being caught. 
     (12) The vehicle door device  20  includes the connection length variable mechanism  35  provided in the second link arm  12  and capable of changing the connection length L between the first rotation coupling point X 1  and the second rotation coupling point X 2 . The second guide member  72  is provided at the second vertical direction position Y 2  corresponding to the second link arm. 
     That is, in a state in which the door-side engagement portion  31  and the vehicle body-side engagement portion  32  are engaged with each other, the opening-and-closing operation trajectory of the door  5  changes from the arc-shaped glide trajectory Rg to the linear slide trajectory Rs based on the operation of the connection length variable mechanism  35 . Therefore, the door  5  can be smoothly closed to the fully closed position and opened from the fully closed position. 
     However, near the position supported by the second link arm  12  provided with the connection length variable mechanism  35 , the orientation change of the door  5  tends to be large. That is, the engagement and disengagement orientation of the axial engagement portion  41  with respect to the guide groove  42  tends to change easily. In view of this point, as in the above-described configuration, the second guide member  72  not having the guide protrusion  73  is provided at the second vertical direction position Y 2  corresponding to the second link arm  12 . Therefore, by securing the degree of freedom of engagement or disengagement of the axial engagement portion  41 , it is possible to effectively prevent the axial engagement portion  41  from being caught. 
     (13) The vehicle door device  20  includes the fixing bracket  53  that fixes the guide member  50  to the installation surface  52  in a state in which the formation portion of the guide groove  42  is sandwiched between the fixing bracket  53  and the installation surface  52  on the vehicle body  2  side set at the close-side end portion  34  of the door opening  3 . 
     According to the above-described configuration, the guide member  50  can be stably fixed to the installation surface  52 . In particular, one side wall portion  42   b  of the guide groove  42  engaged with the axial engagement portion  41  tends to have a cantilever beam structure. However, by sandwiching the formation portion of the guide groove  42  with the installation surface  52 , high strength can be secured. Moreover, the fixing bracket  53  can cover the formation portion of the guide groove  42 . Therefore, the guide groove  42  can be protected, and, for example, clothes of the user can be prevented from being caught by the guide groove  42 . 
     (14) The fixing bracket  53  has the regulation wall  61  that sandwiches the formation portion of the guide groove  42  with the installation surface  52 . The vehicle door device  20  includes the coupling shaft  83  passing through the guide member  50  and the fixing bracket  53  in a state of being parallel to the installation surface  52  and the regulation wall  61 . 
     According to the above-described configuration, when the axial engagement portion  41  abuts against the guide member  50 , a direction in which the guide member  50  is displaced with the coupling shaft  83  as the support shaft is defined. That is, the guide member  50  tends to rotate around the coupling shaft  83  by the abutment of the axial engagement portion  41 . The movement of the guide member  50  is regulated by the installation surface  52  on the vehicle body  2  side or the regulation wall  61  of the fixing bracket  53 , which is located in the rotation direction, and thus the guide member  50  can be stably fixed to the installation surface  52 . 
     (15) The door-side engagement portion  31  includes the roller  48  axially supported to be rotatable by the support shaft  47 . The roller  48  functions as the axial engagement portion  41 . 
     According to the above-described configuration, the axial engagement portion  41  can be smoothly engaged with and disengaged from the guide groove  42 . 
     (16) The vehicle door device  20  includes the actuator  25  that applies a drive force to the link mechanism  15  formed by the first and second link arms  11  and  12  to open and close the door  5 . 
     Therefore, convenience can be improved. 
     Second Embodiment 
     Hereinafter, the second embodiment embodying a vehicle door device will be described with reference to the drawings. For convenience of description, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. 
     As illustrated in  FIGS.  42  to  47   , the present embodiment is different from the first embodiment in a configuration of a guide member  50 B, specifically, a configuration of a buffer member  80 B provided in the guide member  50 B. In the present embodiment, the guide member  50 B illustrated in  FIGS.  42  to  47    is used as the first guide member  71  forming the upper vehicle body-side engagement portion  32   a . The second guide member  72  forming the lower vehicle body-side engagement portion  32   b  is similar to that of the first embodiment (see  FIGS.  18  to  20   ). 
     More specifically, the guide member  50 B of the present embodiment also includes a base member  81 B having the guide groove  42 . Furthermore, in the guide member  50 B of the present embodiment, the base member  81 B is provided with a hole portion  190 . Moreover, the guide member  50 B of the present embodiment is provided with an insertion body  191  inserted into the hole portion  190 . In the guide member  50 B of the present embodiment, the insertion body  191  functions as the buffer member  80 B. 
     Specifically, in the guide member  50 B of the present embodiment, the hole portion  190  has a configuration as a through hole passing through the base member  81 B in the vehicle width direction (in  FIG.  44   , the vertical direction) in a state in which the guide member  50 B is fixed to the installation surface  52  on the vehicle body  2  side. Moreover, the hole portion  190  has a configuration as a groove hole extending in the vehicle horizontal direction (horizontal direction in  FIGS.  43  and  44   ) in a state in which the guide member  50 B is similarly fixed to the installation surface  52 . Accordingly, the guide member  50 B of the present embodiment is configured such that the hole portion  190  opens to the first facing surface  55  forming the side wall portion  42   a  of the guide groove  42 , the guide surface  65  formed by the guide protrusion  73 , and the fixing surface  54  with respect to the installation surface  52 . 
     Furthermore, in the guide member  50 B of the present embodiment, the insertion body  191  has a substantially flat plate shape to be inserted in a state of being fitted into the hole portion  190  provided in the base member  81 B. Moreover, the insertion body  191  is configured such that a first end portion  193  and a second end portion  194  disposed in the vehicle width direction slightly protrude from the hole portion  190  in a state of being inserted into the hole portion  190 . Accordingly, the guide member  50 B of the present embodiment is configured such that the insertion body  191  as the buffer member  80 B is disposed at a position at which the fixing surface  54  with respect to the installation surface  52  and the axial engagement portion  41  of the door-side engagement portion  31  that relatively moves based on the opening-and-closing operation of the door  5  abut. 
     More specifically, in the guide member  50 B of the present embodiment, the first end portion  193  of the insertion body  191  has an end surface shape substantially equal to that of the first facing surface  55  and the guide surface  65  of the guide member  50 B formed by the base member  81 B. Specifically, the insertion body  191  of the present embodiment has the end surface shapes of the side wall portion  42   a  of the guide groove  42  facing outward in the vehicle width direction and the first end portion  193  curved to have the substantially equal shape to the curved shape set to the guide surface  65  continuous with the side wall portion  42   a . Accordingly, the guide member  50 B of the present embodiment is configured such that the first end portion  193  of the insertion body  191  protruding from the hole portion  190  of the base member  81 B and facing outward in the vehicle width direction has a substantially constant protruding amount over the extending direction of the hole portion  190  having the groove hole shape. 
     Furthermore, the second end portion  194  of the insertion body  191  has a substantially flat end surface shape similarly to that of the fixing surface  54  with respect to the installation surface  52 . Accordingly, the guide member  50 B of the present embodiment is configured such that the second end portion  194  of the insertion body  191  protruding from the hole portion  190  of the base member  81 B and facing inward in the vehicle width direction also has a substantially constant protruding amount over the extending direction of the hole portion  190  having the groove hole shape. 
     The guide member  50 B of the present embodiment also includes a plurality of the protrusions  80   x  provided on the second end portion  194  of the insertion body  191  forming the buffer member  80 B. The guide member  50 B of the present embodiment is also configured to be fixed to the installation surface  52  on the vehicle body  2  side in a state in which the protrusions  80   x  are crushed. 
     Moreover, in the guide member  50 B of the present embodiment, the insertion body  191  includes a hole  195  into which the coupling shaft  83  is inserted. Accordingly, the guide member  50 B of the present embodiment is also configured such that the insertion body  191 , the base member  81 B, and the fixing bracket  53  are integrated with each other. 
     As described above, also in the present embodiment, the same effects as those of the first embodiment can be obtained. In addition, the following specific effects can be obtained. 
     The guide member  50 B includes the base member  81 B having the guide groove  42 , and the insertion body  191  forming the buffer member  80 B in a state of being inserted into the hole portion  190  provided in the base member  81 B. 
     According to the above-described configuration, the buffer member  80 B can be appropriately disposed at a position at which the impact when the axial engagement portion  41  abuts against the guide member  50 B can be alleviated. Moreover, the base member  81 B and the buffer member  80 B can be easily and integrally assembled. Therefore, the manufacturing process of the guide member  50 B can be facilitated. 
     (2) The hole portion  190  is provided at a position open to the guide surface  65 . The insertion body  191  forms the buffer member  80 B in a state of protruding to the guide surface  65 . 
     According to the above-described configuration, the buffer member  80 B can be appropriately disposed on the guide surface  65  that comes into contact with the axial engagement portion  41  that comes into contact with and separates from the guide member  50 B based on the opening-and-closing operation of the door  5  and defines the engagement and disengagement trajectory with respect to the guide groove  42 . Therefore, it is possible to effectively alleviate the impact acting on the guide member  50 B due to the abutment of the axial engagement portion  41 . 
     Furthermore, the elastic deformation amount of the buffer member  80 B in accordance with the abutment of the axial engagement portion  41  can be controlled based on the amount of protrusion from the hole portion  190 . That is, the portion protruding to the guide surface  65  is crushed, and thus the axial engagement portion  41  directly abuts on the guide surface  65 . Accordingly, the engagement and disengagement trajectory of the axial engagement portion  41  with respect to the guide groove  42  can be accurately defined. 
     (3) The hole portion  190  has a configuration as a through hole passing through the base member  81 B in the vehicle width direction in a state in which the guide member  50 B is fixed to the installation surface  52  on the vehicle body  2  side. Accordingly, the guide member  50 B is configured such that the insertion body  191  inserted into the hole portion  190  is sandwiched between the axial engagement portion  41  abutting on the insertion body  191  as the buffer member  80 B and the installation surface  52  of the guide member  50 B. 
     According to the above-described configuration, it is possible to elastically deform the insertion body  191  based on the pressing force of the axial engagement portion  41  abutting on the insertion body  191  forming the buffer member  80 B without interposing the base member  81 B. Therefore, it is possible to effectively alleviate the impact acting on the guide member  50 B due to the abutment of the axial engagement portion  41 . 
     Third Embodiment 
     Hereinafter, the third embodiment embodying a vehicle door device will be described with reference to the drawings. For convenience of description, the same components as those of the first embodiment and the second embodiment are denoted by the same reference numerals, and the description thereof will be omitted. 
     As illustrated in  FIGS.  48  to  52   , the present embodiment is also different from the first embodiment and the second embodiment in a configuration of a guide member  50 C, specifically, a configuration of a buffer member  80 C provided in the guide member  50 C. 
     More specifically, similarly to the guide member  50 B in the second embodiment, the guide member  50 C of the present embodiment also includes a hole portion  190 C provided in a base member  81 C and an insertion body  191 C inserted into the hole portion  190 C. The insertion body  191 C functions as the buffer member  80 C. 
     Specifically, the hole portion  190 C of the present embodiment has a slit-like groove shape provided by cutting out the rear end portion  50   r  of the guide member  50 C. Moreover, in comparison with the guide member  50 B of the second embodiment, the groove width of the hole portion  190 C of the present embodiment is set to be wider. Accordingly, the guide member  50 C of the present embodiment is configured such that the insertion body  191 C as the buffer member  80 C inserted into the hole portion  190 C forms a guide surface  65 C at the rear end portion  50   r  of the guide member  50 C. 
     More specifically, the insertion body  191 C of the present embodiment also has a substantially flat plate shape inserted in a state of being fitted to the hole portion  190 C. Furthermore, the insertion body  191  is configured such that a first end portion  193 C side facing outward in the vehicle width direction in a state of being inserted into the hole portion  190 C protrudes from the hole portion  190 C. Specifically, in the guide member  50  of the first embodiment, the insertion body  191 C has a protrusion  196  having substantially the same end surface shape as the guide protrusion  73  forming the guide surface  65  on the first end portion  193 C side. The guide member  50 C of the present embodiment is configured such that the protrusion  196  provided on the first end portion  193 C side of the insertion body  191 C protrudes from the hole portion  190 C of the base member  81 C to form the guide surface  65 C. 
     Also in the base member  81 C of the present embodiment, the hole portion  190 C extends to the front end portion  50   f  side of the guide member  50 C forming the guide groove  42 . Accordingly, the guide member  50 C of the present embodiment is configured such that the insertion body  191 C as the buffer member  80 C inserted into the hole portion  190 C forms a first facing surface  55 C forming the side wall portion  42   a  of the guide groove  42 . 
     Moreover, the guide member  50 C of the present embodiment also includes a plurality of protrusions  80   x  provided on a second end portion  194 C of the insertion body  191 C. The guide member  50 C is configured to be fixed to the installation surface  52  on the vehicle body  2  side in a state in which the protrusions  80   x  are crushed. 
     As described above, also in the present embodiment, the same effects as those of the first embodiment can be obtained. 
     Moreover, in the present embodiment, the insertion body  191 C as the buffer member  80 C inserted into the hole portion  190 C of the base member  81 C forms the guide surface  65 C of the guide member  50 C. 
     According to the above-described configuration, a larger amount of elastic deformation can be secured for the insertion body  191 C as the buffer member  80 C disposed on the guide surface  65 C that defines the engagement and disengagement trajectory with respect to the guide groove  42 . Therefore, it is possible to effectively alleviate the impact acting on the guide member  50 C due to the abutment of the axial engagement portion  41 . 
     Furthermore, since the insertion body  191 C itself forming the guide surface  65 C of the guide member  50 C is elastically deformed, there is an advantage that the axial engagement portion  41  is hardly caught when the axial engagement portion  41  is engaged with or disengaged from the guide groove  42 . Therefore, the rocking of the door  5  caused by the occurrence of the catching can be suppressed, and good operation feeling can be secured. 
     Moreover, the shape of the base member  81 C can be simplified. Accordingly, the manufacturing can be easily performed and the cost can be reduced. In addition, the assemblability of the insertion body  191 C to the base member  81 C can be improved. 
     The above-described embodiments can be modified as below. The above-described embodiments and the following modification examples can be implemented in combination with each other within a range not technically contradictory. 
     In the above-described embodiments, the connection length variable mechanism  35  has a configuration as the joint link mechanism  100  formed by rotatably coupling the vehicle body-side link  91  having the first rotation coupling point X 1  and the door-side link  92  having the second rotation coupling point X 2 . However, the present disclosure is not limited thereto, and the configuration of the connection length variable mechanism  35  may be arbitrarily changed. 
     For example, a linear motion extension and contraction link mechanism  200  as illustrated in  FIGS.  53  and  54    may be provided to a second link arm  12 D as the connection length variable mechanism  35 . That is, the second link arm  12 D illustrated in another example includes an outer tube  201  and an inner tube  202  disposed concentrically. Specifically, the outer tube  201  has the first rotation coupling point X 1  with respect to the vehicle body  2  on a first end portion  201   a  side and an opening portion  201   x  on a second end portion  201   b  side. Furthermore, the inner tube  202  has the second rotation coupling point X 2  with respect to the door  5  on a second end portion  202   b  side and an opening portion  202   x  on a first end portion  202   a  side. Moreover, the inner diameter of the outer tube  201  is set to a value greater than the outer diameter of the inner tube  202 . The second link arm  12 D is configured such that the outer tube  201  and the inner tube  202  are concentrically disposed by inserting the first end portion  202   a  side of the inner tube  202  into the cylinder of the outer tube  201  from the second end portion  201   b  side. 
     That is, in the second link arm  12 D illustrated in another example, the outer tube  201  forms a vehicle body-side link  91 D, and the inner tube  202  forms a door-side link  92 D. The outer tube  201  and the inner tube  202  are relatively displaced in an axial direction, and thus the connection length L between the first and second rotation coupling points X 1  and X 2  changes. 
     Specifically, the outer tube  201  and the inner tube  202  are relatively displaced in a direction in which the inner tube  202  is drawn out from the cylinder of the outer tube  201 , and thus the connection length L between the first and second rotation coupling points X 1  and X 2  is extended. The outer tube  201  and the inner tube  202  are relatively displaced in a direction in which the inner tube  202  is retracted into the cylinder of the outer tube  201 , and thus the connection length L between the first and second rotation coupling points X 1  and X 2  is shortened. 
     Furthermore, the second link arm  12 D illustrated in another example is provided with a biasing member  205  that applies a tensile force in a direction of shortening the connection length L between the first and second rotation coupling points X 1  and X 2 . As the biasing member  205 , for example, a tension spring  206  can be used. By using the biasing force F generated by the biasing member  205 , the connection length L between the first rotation coupling point X 1  and the second rotation coupling point X 2  is held at the time of the opening-and-closing operation of the door  5 . Even when such a configuration is adopted, the same effects as those of the above-described embodiments can be obtained. 
     • Furthermore, in another example, the extension and contraction link mechanism  200  is formed by using the long cylindrical outer tube  201  and inner tube  202  disposed concentrically as the vehicle body-side link  91 D and the door-side link  92 D. However, the present disclosure is not limited thereto, and the vehicle body-side link  91 D and the door-side link  92 D may not necessarily have a cylindrical shape disposed concentrically. As long as the vehicle body-side link  91 D and the door-side link  92 D are disposed so as to be relatively displaceable in an axial direction, the shapes of the vehicle body-side link  91 D and the door-side link  92 D may be arbitrarily changed. 
     A vehicle door device includes: first and second link arms that have a first rotation coupling point with respect to a vehicle body and a second rotation coupling point with respect to a door of a vehicle; a door-side engagement portion that is provided at a close-side end portion of the door that opens and closes a door opening of the vehicle based on operation of a link mechanism formed by the first and second link arms; and a vehicle body-side engagement portion that is provided at a close-side end portion of the door opening that the close-side end portion of the door comes into contact with and separates from based on opening-and-closing operation of the door, in which one side of the door-side engagement portion and the vehicle body-side engagement portion includes an axial engagement portion extending in a vertical direction of the vehicle, the other side of the door-side engagement portion and the vehicle body-side engagement portion includes a guide groove having a pair of side wall portions facing each other in a vehicle width direction and extending in an opening-and-closing operation direction of the door, and the axial engagement portion is disposed inside the guide groove at an opening-and-closing operation position in the vicinity of a fully closed position of the door at which the door-side engagement portion and the vehicle body-side engagement portion are engaged with each other. 
     According to the above-described configuration, the axial engagement portion is disposed inside the guide groove, and thus the displacement of the door in the vehicle width direction is regulated. Therefore, even at the opening-and-closing operation position in the vicinity of the fully closed position at which the first and second link arms are brought closer to each other and are linearly aligned, the door can be stably supported. 
     According to the present disclosure, even in a case where the opening-and-closing operation position of the door is in the vicinity of the fully closed position, the opening-and-closing operation can be performed in a state in which the door is stably supported. 
     The vehicle door device further includes a guide member that forms the guide groove, and the guide member includes a buffer member having elasticity that reduces impact when the axial engagement portion that relatively moves based on the opening-and-closing operation of the door abuts against the guide member. 
     According to the above-described configuration, when the door-side engagement portion and the vehicle body-side engagement portion are engaged with or disengaged from each other based on the opening-and-closing operation of the door, it is possible to effectively alleviate the impact acting on the guide member due to the abutment of the axial engagement portion. Therefore, it is possible to suppress the generation of noise or vibration and secure a high operation feeling. 
     In the vehicle door device, the buffer member is provided at a position at which the axial engagement portion abuts against the guide member. 
     According to the above configuration, the axial engagement portion abuts against the guide member via the elastic buffer member, and thus the impact acting on the guide member due to the abutment of the axial engagement portion can be effectively alleviated. 
     In the vehicle door device, the guide member is fixed to an installation surface set at the close-side end portion of the door or the close-side end portion of the door opening, and the buffer member is provided on a fixing surface with respect to the installation surface. 
     According to the above configuration, the buffer member interposed between the installation surface and the fixing surface of the guide member is elastically deformed, and thus the impact acting on the guide member due to the abutment of the axial engagement portion can be effectively alleviated. 
     In the vehicle door device, the buffer member has protrusions that come into contact with the installation surface and are crushed by the fixing. 
     According to the above-described configuration, since the crushed protrusions reduce backlash, rattling of the guide member fixed to the installation surface can be suppressed. Therefore, a high operation feeling can be secured. 
     In the vehicle door device, the buffer member and the installation surface are preferably located on an extension line in a direction in which the axial engagement portion comes into contact with and separates from based on the opening-and-closing operation of the door. 
     According to the above-described configuration, it is possible to effectively alleviate the impact acting on the guide member due to the abutment of the axial engagement portion. 
     In the vehicle door device, the guide member includes a base member having the guide groove and a covering body forming the buffer member in a state of covering the base member. 
     According to the above-described configuration, the buffer member can be appropriately disposed at a position at which the impact when the axial engagement portion abuts against the guide member can be alleviated. Moreover, for example, the covering body to be the buffer member can be integrally molded with the base member by using two-color molding. 
     Therefore, the manufacturing process of the guide member can be facilitated. 
     In the vehicle door device, the guide member includes a base member having the guide groove and an insertion body forming the buffer member in a state of being inserted into a hole portion provided on the base member. 
     According to the above-described configuration, the buffer member can be appropriately disposed at a position at which the impact when the axial engagement portion abuts against the guide member can be alleviated. Moreover, the base member and the buffer member can be easily and integrally assembled. Therefore, the manufacturing process of the guide member can be facilitated. 
     In the vehicle door device, the base member forms a guide surface continuous with the guide groove, and includes the hole portion opened to the guide surface, and the insertion body forms the buffer member in a state of protruding to the guide surface. 
     According to the above-described configuration, the buffer member can be appropriately disposed on the guide surface that comes into contact with the axial engagement portion that comes into contact with and separates from the guide member based on the opening-and-closing operation of the door and defines the engagement and disengagement trajectory with respect to the guide groove. Therefore, it is possible to effectively alleviate the impact acting on the guide member due to the abutment of the axial engagement portion. 
     Furthermore, the elastic deformation amount of the buffer member in accordance with the abutment of the axial engagement portion can be controlled based on the amount of protrusion from the hole portion. That is, the portion protruding to the guide surface is crushed, and thus the axial engagement portion directly abuts on the guide surface. Accordingly, the engagement and disengagement trajectory of the axial engagement portion with respect to the guide groove can be accurately defined. 
     In the vehicle door device, the guide member includes a guide surface continuous with the guide groove, and the insertion body forms the guide surface. 
     According to the above-described configuration, a larger amount of elastic deformation can be secured for the insertion body as the buffer member disposed on the guide surface that defines the engagement and disengagement trajectory with respect to the guide groove. Therefore, it is possible to effectively alleviate the impact acting on the guide member due to the abutment of the axial engagement portion. 
     Furthermore, since the insertion body itself forming the guide surface of the guide member is elastically deformed, there is an advantage that the axial engagement portion is hardly caught when the axial engagement portion is engaged with or disengaged from the guide groove. Therefore, the rocking of the door caused by the occurrence of the catching can be suppressed, and good operation feeling can be secured. 
     Moreover, the shape of the base member can be simplified. Accordingly, the manufacturing can be easily performed and the cost can be reduced. In addition, the assemblability of the insertion body to the base member can be improved. 
     The vehicle door device is configured such that the insertion body is sandwiched between the axial engagement portion and an installation surface of the guide member set at the close-side end portion of the door or the close-side end portion of the door opening. 
     According to the above-described configuration, it is possible to elastically deform the insertion body based on the pressing force of the axial engagement portion abutting on the insertion body forming the buffer member without interposing the base member. Therefore, it is possible to effectively alleviate the impact acting on the guide member due to the abutment of the axial engagement portion. 
     The vehicle door device further includes a guide member that forms the guide groove, in which the guide member includes a guide surface continuous with the guide groove, and includes first and second guide members that are disposed to be separated from each other in the vertical direction as the guide member, the first guide member has a guide protrusion protruding in a contacting-and-separating direction of the axial engagement portion based on the opening-and-closing operation of the door, the guide protrusion forms the guide surface, and the second guide member does not have the guide protrusion, or an amount of protrusion of the guide protrusion forming the guide surface is smaller than that of the first guide member. 
     According to the above-described configuration, in the first guide member, the engagement and disengagement trajectory of the axial engagement portion with respect to the first guide member is defined by the guide surface formed by the guide protrusion. Furthermore, in the second guide member, the degree of freedom of engagement and disengagement of the axial engagement portion with respect to the second guide member is increased. Accordingly, the axial engagement portions of the first and second guide members are hardly caught by the corresponding first and second guide members when the corresponding axial engagement portions are engaged with or disengaged from the first and second guide members. As a result, the rocking of the door caused by the occurrence of the catching can be suppressed, and good operation feeling can be secured. 
     In the vehicle door device, the first link arm has the second rotation coupling point coupled to the door at a position closer to the center of gravity of the door than the second link arm, and the first guide member is provided at a first vertical direction position corresponding to the first link arm. 
     That is, near the support position by the first link arm configured as described above, the orientation change of the door tends to be small, that is, the engagement and disengagement orientation of the axial engagement portion with respect to the guide groove tends to hardly change. Therefore, by providing the first guide member having the guide protrusion at the first vertical direction position corresponding to the first link arm, it is possible to define the engagement and disengagement trajectory while preventing the axial engagement portion from being caught. 
     The vehicle door device further includes a connection length variable mechanism that is provided in the second link arm and allows changing a connection length between the first and second rotation coupling points, and the second guide member is provided at a second vertical direction position corresponding to the second link arm. 
     According to the above-described configuration, in a state in which the door-side engagement portion and the vehicle body-side engagement portion are engaged with each other, the opening-and-closing operation trajectory of the door changes from the arc-shaped glide trajectory to the linear slide trajectory based on the operation of the connection length variable mechanism. Therefore, the door can be smoothly closed to the fully closed position and opened from the fully closed position. 
     However, near the position supported by the second link arm provided with the connection length variable mechanism, the orientation change of the door tends to be large. That is, the engagement and disengagement orientation of the axial engagement portion with respect to the guide groove tends to change easily. In view of this point, as in the above-described configuration, the second guide member is provided at the second vertical direction position corresponding to the second link arm having the connection length variable mechanism. Therefore, by securing the degree of freedom of engagement or disengagement of the axial engagement portion, it is possible to effectively prevent the axial engagement portion from being caught. 
     The vehicle door device further includes a connection length variable mechanism that is provided in at least one of the first link arm or the second link arm, and allows changing a connection length between the first and second rotation coupling points. 
     According to the above-described configuration, the opening-and-closing operation trajectory of the door can be changed based on the operation of the connection length variable mechanism. 
     The vehicle door device further includes a guide member that forms the guide groove and a fixing bracket that fixes the guide member to an installation surface in a state in which a formation portion of the guide groove is sandwiched between the fixing bracket and the installation surface set at the close-side end portion of the door or the close-side end portion of the door opening. 
     According to the above-described configuration, the guide member can be stably fixed to the installation surface. In particular, one side wall portion of the guide groove engaged with the axial engagement portion tends to have a cantilever beam structure. However, by sandwiching the formation portion of the guide groove with the installation surface, high strength can be secured. Moreover, the fixing bracket can cover the formation portion of the guide groove. Therefore, the guide groove can be protected, and, for example, clothes of the user can be prevented from being caught by the guide groove. 
     In the vehicle door device, the fixing bracket has a regulation wall that sandwiches the formation portion of the guide groove with the installation surface, and includes a coupling shaft passing through the guide member and the fixing bracket in a state of being parallel to the installation surface and the regulation wall. 
     According to the above-described configuration, when the axial engagement portion abuts against the guide member, a direction in which the guide member is displaced with the coupling shaft as the support shaft is defined. That is, the guide member tends to rotate around the coupling shaft by the abutment of the axial engagement portion. The movement of the guide member is regulated by the installation surface or the regulation wall of the fixing bracket, which is located in the rotation direction, and thus the guide member can be stably fixed to the installation surface. 
     In the vehicle door device, the door-side engagement portion has the axial engagement portion, and the vehicle body-side engagement portion has the guide groove. 
     According to the above-described configuration, the door-side engagement portion is less likely to interfere with a user when the user gets on and off the vehicle. Moreover, when the guide groove is provided on the vehicle body-side engagement portion side, for example, clothes of the user are less likely to be caught by the guide groove. Therefore, convenience can be improved. 
     The vehicle door device further includes an actuator that applies a drive force to the link mechanism to open and close the door. 
     According to the above-described configuration, convenience can be improved. 
     In the above-described embodiments, the first link arm  11  having the configuration as the main link  21  is disposed above the second link arm  12  having the configuration as the sub-link  22 . The second link arm  12  is disposed at a position closer to the close-side end portion  33  of the door  5  than the first link arm  11 . However, the present disclosure is not limited thereto, and the arrangement of the first and second link arms  11  and  12  may be arbitrarily changed. 
     In the above-described embodiments, the connection length variable mechanism  35  is provided in the second link arm  12 , but the connection length variable mechanism  35  may be provided in the first link arm  11 . Furthermore, the connection length variable mechanism  35  may be provided in both the first and second link arms  11  and  12 . Since the first and second link arms  11  and  12  and the connection length variable mechanism  35  are disposed, the connection length L between the first and second rotation coupling points X 1  and X 2  may be extended by the operation of the connection length variable mechanism  35  when the door  5  is closed to the fully closed position P 0 . 
     Moreover, the biasing members  115  and  205  of the connection length variable mechanism  35  may be arbitrarily changed. For example, another elastic member such as a compression spring, or a gas biasing member or an electromagnetic biasing member may be used. Furthermore, since the connection length variable mechanism  35  is disposed, a biasing force in a direction of extending the connection length L between the first and second rotation coupling points X 1  and X 2  may be generated. The connection length variable mechanism  35  may not be provided with a biasing member. 
     In the above-described embodiments, the actuator  25  drives the first link arm  11 , but may be configured to drive the second link arm  12 . Furthermore, the actuator  25  may be configured to drive both the first and second link arms  11  and  12 . That is, the number and arrangement of the actuators  25  may be arbitrarily changed. Furthermore, for example, the actuator  25  may be provided on the door  5  side. Moreover, the actuator  25  may be incorporated in the link arm. The configuration of the actuator  25  may also be arbitrarily changed. 
     In the above-described embodiments, the present disclosure is applied to the configuration in which the door  5  of the vehicle  1  performs the opening operation toward the vehicle rear side. However, the present disclosure may be applied to the configuration in which the door  5  performs the opening operation toward the vehicle front side. The present disclosure may be applied to a manual door device having no drive source such as the actuator  25 . 
     In the above-described embodiments, the axial engagement portion  41  is formed by the roller  48  axially supported by the support shaft  47 , but the axial engagement portion  41  does not necessarily need to rotate. 
     In the above-described embodiments, the door-side engagement portion  31  has the axial engagement portion  41 , and the vehicle body-side engagement portion  32  has the guide groove  42 . However, the present disclosure is not limited thereto, and the door-side engagement portion  31  may have the guide groove  42 , and the vehicle body-side engagement portion  32  may have the axial engagement portion  41 . In this case, for example, the guide member  50  may be fixed to the installation surface  43  set at the close-side end portion  33  of the door  5 . 
     In the above-described embodiments, the guide member  50  is fixed to the installation surface  52  by using the fixing bracket  53 . The fixing bracket  53  fixes the guide member  50  between the fixing bracket  53  and the installation surface  52  in a state in which the formation portion of the guide groove  42  provided in the guide member  50  is sandwiched. However, the present disclosure is not limited thereto, and the fixing structure of the guide member  50  may be arbitrarily changed including the shape of the fixing bracket  53 . For example, the regulation wall  61  that sandwiches the formation portion of the guide groove  42  with the installation surface  52  or the coupling shaft  83  passing through the guide member  50  and the fixing bracket  53  in a state of being parallel to the installation surface  52  and the regulation wall  61  may not be provided. For example, the guide member  50  may be directly fixed to the installation surface  52  without using the fixing bracket  53 . 
     In the above-described embodiments, the guide member  50  includes the buffer member  80  that alleviates the impact when the axial engagement portion  41  abuts against the guide member  50 . The buffer member  80  is provided at a position at which the axial engagement portion  41  abuts against the guide member  50 , on the fixing surface  54  of the guide member  50  with respect to the installation surface  52 , and on the guide surface  65  continuous with the guide groove  42 . 
     However, the present disclosure is not limited thereto, and the shape and arrangement of the buffer member  80  may be arbitrarily changed. For example, the buffer member  80  may be provided only at a position at which the axial engagement portion  41  abuts against the guide member  50 . Moreover, the buffer member  80  may be provided only on the guide surface  65 . Furthermore, for example, the buffer member  80  may be provided only on the fixing surface  54  with respect to the installation surface  52 . The buffer member  80  and the installation surface  52  may not necessarily be located on an extension line in a direction in which the axial engagement portion  41  comes into contact with and separates from the guide member  50 . The guide member  50  may not include the buffer member  80 . 
     Furthermore, the number of the protrusions  80   x  crushed by the installation surface  52  may be arbitrarily changed. The buffer member  80  may not have the protrusions  80   x . 
     In the first embodiment, the covering body  82  covering the base member  81  having the guide groove  42  functions as the buffer member  80 . The base member  81  and the covering body  82  are integrally formed by insert molding, more specifically, two-color molding. However, the present disclosure is not limited thereto, and for example, the covering body  82  to be the buffer member  80  may be attached to the base member  81  by adhesion or the like. 
     In the second and third embodiments, the insertion bodies  191  and  191 C for the hole portions  190  and  190 C provided on the base members  81 B and  81 C function as the buffer members  80 B and  80 C. Moreover, the hole portions  190  and  190 C have configurations as through holes penetrating the base members  81 B and  81 C. Accordingly, the insertion bodies  191  and  191 C as the buffer members  80 B and  80 C inserted into the hole portion  190  and  190 C are provided at the position at which the axial engagement portion  41  abuts, and on the fixing surface  54  with respect to the installation surface  52 . However, the present disclosure is not limited thereto, and the shapes of the hole portions  190  and  190 C and the insertion bodies  191  and  191 C may be arbitrarily changed. For example, the insertion bodies  191  and  191 C are not necessarily configured to be sandwiched between the axial engagement portion  41  abutting on the insertion bodies  191  and  191 C and the installation surface  52 . As in the above-described another example, the covering body  82  to be the buffer member  80  may be combined with a configuration in which the covering body  82  is attached to the base member  81 . 
     In the above-described embodiments, as the guide member  50 , the first and second guide members  71  and  72  that are disposed to be separated from each other in the vertical direction are provided. The first guide member  71  has the guide protrusion  73  protruding in the contacting-and-separating direction of the axial engagement portion  41  based on the opening-and-closing operation of the door  5 , and the guide protrusion  73  forms the guide surface  65 . The second guide member  72  does not have the guide protrusion  73 . However, the present disclosure is not limited thereto, and the second guide member  72  may be configured such that a protrusion amount a of the guide protrusion  73  forming the guide surface  65  is smaller than that of the first guide member  71 . Even when such a configuration is adopted, the degree of freedom of engagement and disengagement of the axial engagement portion  41  with respect to the second guide member  72  is increased, and the axial engagement portion  41  can be made less likely to be caught. 
     Furthermore, in a case where the first and second guide members  71  and  72  have different shapes, the buffer member  80  may be provided in the second guide member  72 . Therefore, it is possible to more effectively suppress noise and vibration generated when the axial engagement portion  41  abuts and to secure a high operation feeling. 
     Furthermore, the second guide member  72  may have the same configuration as that of the first guide member  71 . Therefore, a stable engagement and disengagement trajectory of the axial engagement portion  41  can be more effectively defined by the guide surface  65  formed by the guide protrusion  73 . 
     Furthermore, the number and arrangement of the door-side engagement portions  31  and the vehicle body-side engagement portions  32  may be arbitrarily changed. The first guide member  71  having the guide protrusion  73  may be only required to be provided at a vertical direction position close to the center of gravity G of the door  5 . The second guide member  72  is provided at a height position at which the connection length variable mechanism  35  is disposed. That is, in comparison with the first guide member  71 , it is only required to provide the guide member  50  which does not have the guide protrusion  73  or in which the protrusion amount a of the guide protrusion  73  forming the guide surface  65  is smaller as in the above-described another example. 
     Next, a technical idea that can be grasped from the above-described embodiments and modification examples will be described. 
     (A) The guide member includes a guide surface continuous with the guide groove, and the buffer member is provided on the guide surface. 
     That is, the axial engagement portion that is engaged with or disengaged from the guide groove of the guide member based on the opening-and-closing operation of the door is guided in a direction of entering the guide groove and in a direction of disengaging from the guide groove by abutting on the guide surface. According to the above-described configuration, it is possible to effectively alleviate the impact acting on the guide member due to the abutment of the axial engagement portion. 
     (B) The axial engagement portion is axially supported to be rotatable. 
     According to the above-described configuration, the axial engagement portion can be smoothly engaged with and disengaged from the guide groove. 
     The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.