Abstract:
A vehicle includes at least one tailgate defining a door plane, wherein the tailgate is attached to the vehicle chassis in a jointed fashion by at least one multiple hinge having at least three pivot axes offset from one another and at least two pairs of pivotally connected hinge arms, of which a first hinge arm is pivotally connected to the vehicle chassis and a second hinge arm is pivotally connected to the tailgate. The multiple hinge is associated with a drivetrain controlling the motion of the hinge arms in the pivot axes. The door plane is moved along a predetermined motion path when the tailgate travels from a closed position, in which the tailgate spans a closed plane, to an open position, in which the tailgate spans an opening plane. The motion path of the door plane includes rotary and translational components, and the closed plane forms an angle to the opening plane in the range from 70° to 110°, preferably about 90°.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a Continuation Application of PCT/EP2008/005498, and claims priority from International Application PCT/EP2008/005498 filed Jul. 4, 2008 and German Application DE 10 2007 033 281.7 filed Jul. 17, 2007, the entire disclosure of each of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a vehicle having at least one tailgate attached to the vehicle by means of a suspension. 
       BACKGROUND OF THE INVENTION 
       [0003]    A similar vehicle and a similar suspension for a vehicle side door are known from DE 10 2004 042 808 A1. The suspension described therein comprises an articulated arm system including at least two bending-resistant articulated arms interconnected via a joint, of which a first articulated arm is connected via a joint to a carrier fastened to the chassis frame, and a second articulated arm is connected with its free end via a joint to a support element fastened to the door. The articulated arm system has assigned thereto a gear train with transmission elements for the parallel movement of the door between a closed position and a front or rear opening position. With this suspension the door is first moved away from the vehicle for a short time during the opening operation and is then guided along in parallel with the side of the vehicle. Hence, the suspension only allows for a parallel displacement of the vehicle door. In some cases, e.g., in tailgates of vehicles or also in vehicles with a short tail, the side doors of which are shifted rearwards, i.e., in those vehicles in which the doors in the opened state would project far beyond the vehicle laterally or rearwards, such a parallel displacement is unwanted. 
       SUMMARY OF THE INVENTION 
       [0004]    It is therefore the object of the present invention to provide a vehicle of the aforementioned type that exhibits an improved design of the door suspension and door opening, respectively, above all for tailgates. 
         [0005]    For this purpose it is provided according to the invention that the vehicle comprises at least one tailgate defining a door plane, said tailgate being attached to the vehicle chassis in a jointed fashion by means of at least one multiple hinge having at least three pivot axes offset from one another and at least two paired, pivotally interconnected hinge arms, of which a first hinge arm is pivotally connected to the vehicle chassis and a second hinge arm is pivotally connected to the tailgate, the multiple hinge being associated with a gear train controlling the hinge motion of the hinge arms in the pivot axes, whereby the door plane is moved along a predetermined motion path when the tailgate is moved from a closed position, in which the tailgate spans a closed plane, into an open position, in which the tailgate spans an opening plane, the motion path of the door plane comprising rotary and translational components, and the closed plane enclosing an angle with the opening plane in the range from 70° to 110°, preferably about 90°. 
         [0006]    As a result, the tailgate while being opened performs not only a parallel movement, but is also pivoted. Consequently, the opened tailgate no longer projects far beyond the vehicle, but is laterally arranged in parallel with the vehicle side. The vehicle will then have a large loading opening. 
         [0007]    According to a variant the length of the hinge arms is fixed such that the tailgate is arranged in the open position at a lateral distance next to a side of the vehicle. In the open position the tailgate is disposed completely next to the vehicle, whereby a rearward viewing onto the vehicle is not obstructed in any way. Taillights, warning lights, flashers, and other lights are thus not concealed by the opened tailgate. 
         [0008]    According to a preferred configuration the tailgate is arranged in the open position approximately up to half the door width next to the vehicle. This makes the opening curve or motion path of the door plane flatter. Both during opening of the tailgate and in the open position of the tailgate the space needed at the rear, behind the vehicle, is smaller. 
         [0009]    In an expedient embodiment, the first hinge arm may be connected on a first pivot axis to the vehicle chassis and the length of the first hinge arm corresponds at least to the depth of the tailgate. As a result, the tailgate can be moved out of the door plane in an easy way. In the open position the tailgate can easily be arranged laterally next to the vehicle. 
         [0010]    In a further expedient embodiment, it may be provided that the second hinge arm is connected on a second pivot axis to a rigid carrier of the tailgate, and the distance between the second pivot axis and the connection of the first hinge arm to the vehicle chassis corresponds to about ⅔ of the width of the tailgate. It can thereby be ensured on the one hand that the tailgate in the open position is arranged at an adequate lateral distance from the side of the vehicle and on the other hand the torque acting on the multiple hinge gets thereby smaller. 
         [0011]    In a further variant, the second hinge arm may be longer than the first hinge arm. This makes it possible that the tailgate is arranged in the open position laterally next to the vehicle and does not project too much rearwards beyond the vehicle tail. The lateral distance of the tailgate to the vehicle can be varied by changing the length of the second hinge arm. 
         [0012]    Expediently, the gear train is configured such that the gear ratio between the second hinge arm and the rigid carrier of the tailgate to the gear ratio between the vehicle chassis and the first hinge arm and to the gear ratio between the first hinge arm and the second hinge arm is negative. Therefore, when the tailgate is opened, the rotational angle between the rigid carrier and the second hinge arm is decreasing, while the rotational angle between the vehicle chassis and the first hinge arm and between the first hinge arm and the second hinge arm is increasing. The rigid carrier is thereby rotated in a direction opposite to the two hinge arms when the tailgate is opened. The tailgate is moved next to the vehicle in such a way that it is arranged in parallel with the vehicle side in the open position. It is thereby easier to adjust the lateral distance between the attachment of the multiple hinge to the vehicle chassis and the position of the tailgate in the opened state. 
         [0013]    In a further advantageous embodiment it may be provided that the gear train is configured such that the gear ratio between the vehicle chassis and the first hinge arm exactly corresponds to the gear ratio between the first hinge arm and the second hinge arm and exactly to the absolute value of the gear ratio between the second hinge arm and the rigid carrier of the tailgate. Thus the first hinge arm is always displaced by the same angle as the second hinge arm whereas the rigid carrier of the tailgate is adjusted by the same angle, but in opposite rotational direction. As a result, the gear train can be configured in a very simple way. 
         [0014]    Preferably, in the open position of the tailgate an angle α′ spanned between the vehicle chassis and the first hinge arm is about 90°, an angle β′ spanned between the extension of the first hinge arm and the second hinge arm is about 90°, and an angle γ spanned between the extension of the second hinge arm and the rigid carrier of the vehicle chassis is about 0°. With this suitable selection of the angles in the open position it is easily achieved that the tailgate is arranged in the open position in parallel with the side of the vehicle and encloses an angle of about 90° with the closed plane. Since the opening angles have the same gear ratio or the same magnitude of the gear ratio, the gear train can be designed in a simple way. 
         [0015]    Preferably, the gear train is formed by toothed belt connections. This accomplishes a slip-free connection of low friction and low noise emission. 
         [0016]    However, it may also be provided that the gear train comprises toothed wheel gears and toothed belt connections. The toothed wheel gears permit a high loadability and require little space. 
         [0017]    In a further configuration the tailgate may be connected via two multiple hinges with associated gear trains to the vehicle chassis. Higher loads can thereby be carried, which is particularly advantageous in the case of large and heavy tailgates. 
         [0018]    Expediently, at least one motor can be assigned to the at least one multiple hinge with the gear train. The tailgate can then be opened and closed via the motor; forces need no longer be exerted. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Embodiments of the present invention will now be explained in more detail with reference to a drawing, in which: 
           [0020]      FIG. 1  is a schematic illustration of a tailgate in different positions; 
           [0021]      FIG. 2  shows an embodiment of a multiple hinge with associated gear train; 
           [0022]      FIG. 3  is a perspective view of two superposed multiple hinges attached to the vehicle chassis; and 
           [0023]      FIG. 4  shows the tailgate with two multiple hinges according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]      FIG. 1  is a schematic view showing a tailgate  2  attached to a vehicle chassis  1 , in different positions. The tailgate  2  is fastened via a multiple hinge  3  to the vehicle chassis  1 . The tailgate  2  defines a door plane  24 . In the illustration drawn with continuous lines, the tailgate  2  is closed and is positioned in a closed plane  22 . The door plane  24  is then identical with the closed plane  22 . In the illustration with broken lines the tailgate  2  is located in an intermediate position during the opening process. The door plane  24  encloses an angle with the closed plane  22 . The illustration plotted with dash-dotted lines shows the tailgate  2  in a fully opened position, in which the tailgate  2  is located in an opening plane  23 . The door plane  24  is thus identical with the opening plane  23  in this position. 
         [0025]    The multiple hinge  3  comprises a first hinge arm  4  and a second hinge arm  5 , which are rotatably interconnected on a pivot axis  6 . The first hinge arm  4  is rotatably connected at its free end on a pivot axis  7  to the vehicle chassis  1 . The second hinge arm  5  is rotatably connected at its free end on a pivot axis  8  to a rigid carrier  9  fastened to the tailgate  2 . However, it would also be conceivable to fasten the second hinge arm  5  via a rigid connection directly to the tailgate  2 . 
         [0026]    The pivot axes  6 ,  7 ,  8  have assigned thereto gear elements  10 ,  11 ,  12  forming a gear train. When the tailgate  2  is moved out of the closed position into the opening position, the door plane  24  is moved by the gear train along a predetermined motion path. The gear elements  10 ,  11 ,  12  are kinematically interconnected, so that the motion path of the door plane  24  is constant all the time. The motion paths of the individual components of the multiple hinge  3 , and thus the motion path of the door plane  24 , are set via the gear ratios of the individual gear elements  10 ,  11 ,  12 . 
         [0027]    Since the tailgate  2  is moved through a combination of rotation and displacement from the closed position into the open position, the closed plane  22  and the opening plane  23  enclose an angle. This angle is in the range of 70° to 110° and is preferably 90°. During opening the tailgate  2  is thus not only shifted in parallel, but is also pivoted. 
         [0028]      FIG. 2  is an enlarged perspective view showing the multiple hinge  3 , wherein the second hinge arm  5  is not shown in its full length. 
         [0029]    The first hinge arm  4  is rotatably supported on the pivot axis  7  in the vehicle chassis  1 . To this end the vehicle chassis  1  has assigned thereto a toothed structure  14  on the pivot axis  7 . On the hinge arm  4 , a toothed wheel  15  is mounted, which engages into the toothed structure  14  of the vehicle chassis  1 . The toothed structure  14  and the toothed wheel  15  form the gear element  10 . 
         [0030]    The first hinge arm  4  and the second hinge arm  5  are rotatably mounted with one another on the pivot axis  6 . The gear element  11  is arranged on this pivot axis  6 . The gear element  11  comprises a toothed wheel  16  arranged on the first hinge arm  4 , and a toothed structure  17  arranged on the second hinge arm  5 , the toothed wheel  16  and the toothed structure  17  meshing with each other and transmitting movements of the one hinge arm  4 ;  5  to the respectively other hinge arm  5 ;  4 . 
         [0031]    At its other end the second hinge arm  5  is rotatably supported on a further pivot axis  8  on the rigid carrier  9  of the tailgate  2 . The pivot axis  8  has assigned thereto a further gear element  12 . The gear element  12  comprises a toothed wheel  18  which is arranged on the second hinge arm  5  and which is connected via a toothed belt  19  to a toothed wheel  20  arranged on the rigid carrier  9 , so that the second hinge arm  5  can be pivoted about the rigid carrier  9 . 
         [0032]      FIG. 3  is a perspective view showing two superposed multiple hinges  3 , in which the second hinge arm  5  is shown in its full length. The first hinge arm  4  is connected at one end to the vehicle chassis  1 ; the second hinge arm  5  is connected at one end to the rigid carrier  9 , which is attached to an accommodating duct  21  assigned to the tailgate  2 . As has already been described, the gear train is formed on the first pivot axis  7  by a toothed structure  14  assigned to the vehicle chassis  1  and by a toothed wheel  15  assigned to the first hinge arm  4 , on the second pivot axis  6  by a toothed wheel  16  assigned to the first hinge arm  4  and by a toothed structure  17  arranged on the second hinge arm  5 , and on the third pivot axis  8  by a toothed wheel  18  assigned to the second hinge arm  5  and by a toothed wheel  20  assigned to the rigid carrier  9 , which are interconnected via a toothed belt  19 . However, it is also conceivable that other mechanisms are used in the gear train, e.g. only toothed belts or also chains. 
         [0033]    In the closed position of the tailgate  2 , the multiple hinge  3  is arranged in the accommodating duct  21  of the tailgate  2 . The stiffness of the tailgate  2  can be enhanced through the accommodating duct(s)  21 . To this end additional struts may be mounted between the accommodating ducts  21 . Preferably, the struts should be mounted on the upper accommodating duct at the place where the rigid carrier is arranged so as to absorb arising forces. Hence, the accommodating ducts  21  are interconnected via the struts and can therefore form the supporting structure of the tailgate  2 . All of the essential elements, such as for instance the lock or the closing mechanism, are then mounted on the accommodating ducts  21 . The forces arising on the tailgate  2  are absorbed and passed on, respectively, by the accommodating ducts  21  and the struts connecting the accommodating ducts. The visible outer skin of the tailgate  2  is thus only a casing. The tailgate  2  can thereby be implemented as a lightweight structure. 
         [0034]      FIG. 4  is a perspective view showing the tail portion of a vehicle according to the invention with a tailgate  2  arranged thereon. Both the tailgate  2  and the vehicle chassis  1  are only schematically shown in  FIG. 4 . The tailgate  2  is here connected via two multiple hinges  3  to the vehicle chassis  1 . The multiple hinges  3  are of identical construction with respect to each other, each of the multiple hinges  3  comprising three pivot axes  6 ,  7 ,  8 . However, it would also be conceivable to design the multiple hinges such that in each multiple hinge only two pivot axes are provided. The accommodating ducts for the multiple hinges are here not shown. 
         [0035]    In  FIG. 4 , the tailgate  2  is being opened and is located in a central opening position. The length of the hinge arms  4 ,  5  is defined such that the tailgate  2  is arranged in the open position at a lateral distance next to a side of the vehicle. The tailgate  2  is here arranged up to about half the door width next to the vehicle. 
         [0036]    The multiple hinge  3  is preferably configured such that the second hinge arm  5  is longer than the first hinge arm  4  and also longer than the rigid carrier  9 . 
         [0037]    The length of the first hinge arm  4  corresponds here at least to the depth of the tailgate  2 . The distance between the rigid carrier  9  of the tailgate  2  and the pivot axis  7 , and the connection of the first hinge arm  4  to the vehicle chassis, respectively, is about ⅔ of the width of the tailgate  2 . 
         [0038]    Furthermore, it may be provided that a motor is arranged next to the vehicle chassis  1 , the motor communicating with the gear train or with one of the gear elements  10 ,  11 ,  12 , so that the tailgate  2  can be opened and closed by the motor. 
         [0039]    The operation of the tailgate  2  and of the multiple hinge  3 , respectively, will now be described in more detail with reference to  FIGS. 1 to 4 . 
         [0040]    As has already been described,  FIG. 1  shows various positions the tailgate  2  can assume. Continuous lines show the closed position in which the tailgate  2  is positioned in a closed plane  22 . The dash-dotted lines show the open position in which the tailgate  2  is positioned in the opening plane  23 . The tailgate  2  defines the door plane  24 , which in the closed position of the tailgate  2  is identical with the closed plane  22  and which in the open position of the tailgate  2  is identical with the opening plane  23 . When the tailgate  2  is moved from the closed position into the open position, the door plane  24  is moved by the gear train along a predetermined, always invariable motion path. The motion paths of the individual components of the multiple hinge  3 , and thus the motion path of the door plane  24 , are adjusted by the gear ratios of the gear elements  10 ,  11 ,  12  of the gear train. The gear train is here configured such that the motion path of the door plane  24  comprises rotary and translational components. 
         [0041]    The opening operation of the tailgate  2  can e.g. be started in that a user operates a door handle and pulls the tailgate  2 , and thus also the rigid carrier  9 , to the outside. Since all components of the multiple hinge  3  are kinematically interconnected via the gear train, a movement of one of the components results in a movement of all of the other components in a predetermined way and the door plane  24  delineates the predetermined motion path. Hence, the movement of the rigid carrier  9  is transmitted on the joint or pivot axis  8  via the associated gear element  12  to the second hinge arm. The movement of the second hinge arm  5 , in turn, is transmitted via the pivot axis  6  and the associated gear element  11  to the first hinge arm  4 , which then pivots along the pivot axis  7  and with the help of the gear element  10  about the vehicle chassis  1 . 
         [0042]    In the closed position of the tailgate  2 , the first hinge arm  4  and the second hinge arm  5  form a straight line; the rigid carrier  9  encloses an angle γ 0  of 90° with the extension of the second hinge arm  5 . After initiation of the door opening process, e.g. by operating a door handle or an automatic door opener, the tailgate  2  is moved outwards. The gear ratio of the gear element  12  is chosen such that the rigid carrier  9  is pivoted along the pivot axis  12  in such a way that the angle γ, which is spanned between the extension of the second hinge arm  5  and the rigid carrier  9 , is decreasing. The movement of the rigid carrier  9  is transmitted via the gear element  12  to the second hinge arm  5 . The gear elements  11 ,  12  are preferably configured such that the angle β spanned between the first hinge arm  4  and the second hinge arm  5  is increasing to the extent the angle γ is decreasing. The movement of the second hinge arm  5  is transmitted via the gear element  11  to the first hinge arm  4 . In this instance, too, the gear elements  10 ,  11  are again configured such that the angle α spanned between an extension of the vehicle chassis  11  and the first hinge arm  4  is increasing to the same extent as does the angle β. This is made possible by pivoting the first hinge arm  4  on the pivot axis  7 . 
         [0043]    Since the motion path of the door plane  24  as defined by the gear elements  10 ,  11 ,  12  shows rotary and translational components, the tailgate  2  is moved in the opening process such that it is pivoted from the closed position, in which it is positioned in parallel with the vehicle tail, into an open position, in which the tailgate  2  is substantially arranged in parallel with the corresponding side wall of the vehicle chassis  1 . As can be seen in  FIG. 1 , the angles α and β in the closed position of the tailgate  2  are 0°; the angle γ 0  is 90°. In the illustrated open position the angles α′, β′ are about 85°; the angle γ′ is about 5°. The gear train is thus configured such that the gear ratio on the pivot axes  6 ,  7  assumes the value 1 and on the pivot axis  8  the value −1. Hence, the gear ratio between the rigid carrier  9  of the tailgate  2  and the second hinge arm  5  has an opposite sign with respect to the gear ratio between the first hinge arm  4  and the second hinge arm  5  and the gear ratio between the first hinge arm  4  and the vehicle chassis  1 ; the absolute values of the gear ratios are identical. This has the effect that the angles α and β are increasing when the tailgate  2  is opened, whereas the angle γ is decreasing when the tailgate  2  is opened. 
         [0044]    It is also conceivable that the gear ratio assumes other values, but attention must be paid that the gear ratio on the pivot axis  8 , i.e., of the gear elements  12 , has an opposite sign with respect to the gear ratios on the gear elements  10  and  11 .