Abstract:
A tailgate of a motor vehicle has a vibration absorber configured as a spring-mass system. In order to reduce a vibrating of the tailgate in the driving mode, it is provided that the vibration absorber is fastened as a separate component to the tailgate. The advantages mainly obtained are that of enabling the separate absorber mass to be coordinated with the tailgate in a simple manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the priority, under 35 U.S.C. §119, of German application DE 10 2005 046 891.8, filed Sep. 30, 2005; the prior application is herewith incorporated by reference in its entirety.  
       BACKGROUND OF THE INVENTION  
     FIELD OF THE INVENTION  
       [0002]     The invention is based on a tailgate of a motor vehicle, which has a vibration absorber configured as a spring-mass system.  
         [0003]     A tailgate forming the generic type is known from German patent DE 195 24 160 C1. The tailgate there itself forms the absorber mass which is supported in relation to the body shell of the motor vehicle via a spring/damper system. The spring/damper system together with the absorber mass therefore constitutes the spring-mass system. The spring/damper system in the known tailgate is configured as a rubber element on which the lock bow of the tailgate lock is supported. Alternatively, the seal which surrounds the bodywork opening and on which the tailgate rests can serve as the spring/damper system.  
         [0004]     Published, non-prosecuted German patent DE 40 30 990 A1 reveals, as a vibration absorber, a spring-mass system which is disposed in a windshield frame of a convertible.  
       SUMMARY OF THE INVENTION  
       [0005]     It is accordingly an object of the invention to provide a tailgate of a motor vehicle which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which, while having a simple construction, is adequately damped in its vibration behavior.  
         [0006]     With the foregoing and other objects in view there is provided, in accordance with the invention, a tailgate of a motor vehicle. The tailgate contains a vibration absorber configured as a spring-mass system, the vibration absorber being fastened as a separate component to the tailgate.  
         [0007]     The advantages mainly obtained with the invention are considered that of enabling the separate absorber mass to be coordinated with the tailgate in a simple manner. Thus, the vibration absorber according to the invention, which is fastened as a separate component to the tailgate, for example is matched to tailgates in different ways, since the latter may differ in weight. In particular, optional equipment items of the motor vehicle may influence the weight of the tailgate. Optional equipment items of this type may be, for example, optionally provided wipers, opening aids for the tailgate, different rear windows for the tailgate, or the like. In the case of the tailgate known from the prior art, these optional equipment items may lead to a miscoordination of the spring-mass system, as a result of which the absorber effect may possibly no longer be satisfactory. Furthermore, it has been shown that the vibration absorber according to the invention can also be used for tailgates which are used in vehicles with a body in the manner of a coupe. In the case of vehicles of this type, the tailgate lies in a plane which is inclined only by a small angle in relation to an imaginary horizontal plane. In the case of configurations of this type, the tailgate may have an increased tendency to vibrate. However, it has been shown that, with the vibration absorber according to the invention, even tailgates of this type can be damped such that the knocking noises, which are described in the prior art, within the motor vehicle can be completely prevented or at least very largely avoided.  
         [0008]     According to a development of the invention, it is advantageous for the damping of the tailgate to be able to take place with a relatively small absorber mass.  
         [0009]     In the case of an exemplary embodiment, the space which already exists in many cases between an outside panel and an inside panel of the tailgate is used for the arrangement of the vibration absorber. Additional installation space for the vibration absorber therefore does not need to be provided.  
         [0010]     An exemplary embodiment is particularly preferred, according to which the vibration absorber is inserted into a recess on the inside panel. The vibration absorber can accordingly be suspended on the edge surrounding the recess.  
         [0011]     In an exemplary embodiment, the vibration absorber is covered by an interior trim panel.  
         [0012]     In order to be able to suspend the vibration absorber permanently and securely, the edge which surrounds the recess is of reinforced construction, preferably peripherally. The reinforcement of the edge can be formed, for example, by an inside panel which is configured with a greater material thickness in the region of the edge than in other regions. Panels of this type are also referred to as tailored blanks. However, an exemplary embodiment is particularly preferred, in which the reinforcement of the edge is formed by a separate reinforcing part which is placed onto the inside panel. The reinforcing part is preferably configured as a peripheral frame and is connected to the inside panel of the tailgate. In this case, the reinforcing part can be a sheet-metal part.  
         [0013]     In order to provide an enlarged installation space for the vibration absorber, the edge of the recess can be configured as a protuberance or can have a protuberance. There is therefore increased space between inside panel and outside panel.  
         [0014]     Other features which are considered as characteristic for the invention are set forth in the appended claims.  
         [0015]     Although the invention is illustrated and described herein as embodied in a tailgate of a motor vehicle, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.  
         [0016]     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a diagrammatic, perspective view of a motor vehicle with a tailgate according to the invention; and  
         [0018]      FIG. 2  is diagrammatic, perspective view of the tailgate from the inside. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, there is shown a motor vehicle  1  that contains a body  3 , which is supported by wheels  2 , with a bodywork  4  which, in a rear region  5 , has a bodywork opening  6  into which a tailgate  7  is inserted. The tailgate  7  is shown in  FIG. 1  in a closed position ST in which it is substantially flush with the outer skin  8  of the bodywork  4 . The tailgate  7  can be folded about a pivot axis  9 , which runs transversely to a vehicle longitudinal axis FL, into an open position. For this purpose, hinges  12  and  13  (see  FIG. 2 ) are fitted in the upper corner regions  10  and  11  of the tailgate  7  and are also connected to the body  3 . The tailgate  7 , which has a large surface area, has a window cutout  14  into which a rear window  15  is fixedly inserted. The window cutout  14  is bounded by lateral frame parts  16  and  17  which are connected to each other in the corner regions  10  and  11  via a transverse frame part  18 . A lower boundary edge  19  of the window cutout  14  is adjoined by an opaque section  20  of the tailgate  7 . The section  20  is formed by an outside panel which also has the frame parts  16  and  17  and the frame transverse part  18 . An outside panel  21  consequently has the window cutout  14 . To support the outside panel  21 , an inside panel  23 , which likewise has the window cutout  14 , is fastened to the side of the outside panel which faces a vehicle interior  22 . The inside panel  23  and the outside panel  21  are preferably connected fixedly to each other at least on an outer tailgate edge  24 . A partial region of the inside panel  23  situated below the section  20  has one or more recesses  25 ,  26 ,  27 ,  28  of which a recess  26  lies adjacent to the lower boundary edge  19  and approximately on the vehicle longitudinal axis FL, i.e. is formed approximately centrally in the inside panel  23 . With regard to the measured length of the tailgate  7  in the direction of the vehicle longitudinal axis FL, the recess  26  is likewise formed on the tailgate  7  approximately centrally. A driving motor  29  for a rear window wiper  30  ( FIG. 1 ) can be inserted into another, in particular lateral recess  25  or  27 .  
         [0020]     The central recess  26  is bounded by an edge  31  which has a protuberance  32  which is directed in the direction of the vehicle interior  22  and furthermore can also be provided for the other recesses  25 ,  27 ,  28 . The protuberance  32  consequently forms an elevation on the inside of the inside panel  23 , which side faces the vehicle interior  22 , and enlarges the intermediate space present between inside panel  23  and outside panel  21 .  
         [0021]     A vibration absorber  33 , which is configured as a spring-mass system and therefore has an absorber mass  34  and at least one spring element  35  as a suspension device, is inserted as a separate component into the central recess  26 . In the exemplary embodiment shown, the absorber mass  34  is suspended by two spring elements  35 . For this purpose, the spring elements  35 , which can have a damping effect, are connected to the edge  31  of the inside panel  23 , so that the vibration absorber  33  comes to lie within the central recess  26 . In this case, the vibration absorber  33  is fastened to the inside panel  23  in such a manner that it comes to lie at least in some sections within the tailgate  7  in the intermediate space bounded by the outside panel  21  and inside panel  23 . For secure suspension of the vibration absorber  33 , the edge  31  of the recess  26  is of reinforced construction. A reinforcement can surround the recess  26  in a strip-shaped manner or in the manner of a frame. The reinforcement is configured on the inside of the inside panel  23 , which side faces the vehicle interior  22 , as a separate reinforcing part  36  in the form of a peripheral frame which is connected fixedly to the inside panel  23 . The peripheral frame of the reinforcing part  36  is preferably configured as a sheet-metal part. Alternatively, it would be conceivable to fasten the reinforcing part  36  to that side of the inside panel  23  which faces the outside panel  21 . In a further embodiment, the inside panel  23  could also be configured as a tailored blank which has a material section with greater material thickness as reinforcing part  36  in the region of the edge  31 . The strip-shaped reinforcing part  36  preferably extends over the entire protuberance  32  of the recess  26 .  
         [0022]     A non-illustrated interior trim panel for the tailgate can also be fitted on the inside of the inside panel  23 , which side faces the vehicle interior  22 , as a result of which the parts fitted to the tailgate  7 , such as, for example, the driving motor  29  and the vibration absorber  33 , are covered by the interior trim panel.  
         [0023]     As  FIG. 1  also shows, the motor vehicle  1  is configured as a passenger vehicle, and, in the vehicle interior  22  behind a front seat row  37  or rear seat row  38 , it has a loading compartment  39  or luggage compartment which is upwardly closed or opened up by the tailgate  7 . The body  3  of the motor vehicle  1  is realized, in particular, as a coupe with a rear region  5  dropping to the rear in a relatively shallow manner. The tailgate  7  is therefore situated in a plane which, with respect to an imaginary horizontal plane in which, for example, a belt line  40  of the body  3  is situated, takes up an angle a which is smaller than 90°, in particular smaller than 45°, and, for example, lies between 10° and 35°.