This invention relates to a roof frame arrangement of motor vehicles.
In conventional motor vehicles, in particular in “station wagons”, the roof frame comprises a multiplicity of individual sheet-metal pressed parts which are joined to form an inner shell and an outer shell which, for their part, are joined, in particular welded, to form a hollow profile with a hollow space. The supporting device for the tailgate which can be pivoted upward is formed by hinges which are fastened at one end to the rear roof frame. In addition, the tailgate is also supported by gas-filled springs which are coupled at one end to the rear post of the body work and at the other end directly to the tailgate. In order to ensure the bodywork is leak proof particularly in the end region of the lateral roof frame which is open to the rear in the unfinished state, these shells have to be sealed to the outside in the flange regions in a complex and careful manner. This frequently requires environmentally incompatible sealants. Furthermore, a disadvantage arises with regard to the structural space which is to be provided due to the necessary welding flanges, with relatively large structural spaces being required without substantially increasing the hollow profile cross section which has been produced. Furthermore, the multipart nature and the welding connections, which are affected by distortion, give rise to tolerance problems which, in respect of the connection to the rear roof frame, also hinder the possibility of sealing the arrangement and have the consequence that the roof frame arrangement is complicated to align.
A roof frame arrangement is disclosed in German publication DE-C 27 44 927; in this arrangement, the design of the entire roof frame is not discussed specifically, but the arrangement has a hollow space at the rear end in the upper corners of the flap opening. The hollow space is formed by the sheet metal of the rear post, by the sheet metal of the roof frame and by the roof itself. The supporting device for a tailgate of a motor vehicle is held in this hollow space, and the gas-filled compression spring, which is fastened in a vertically pivotable manner, is connected in a hinged manner to the tailgate hinge.
This invention is based on the object of providing a roof frame arrangement having increased stiffness, which can be produced in a simple and space-saving manner and with as few manufacturing tolerances as possible, and in which a relatively great outlay on leakproofness is not required.
The object is achieved according to the invention.
Owing to the fact that the rear end region of the lateral roof frame, which is open to the rear in the unfinished state, has a single-piece, circumferentially closed hollow profile, the stiffness of the frame is particularly increased in a simple manner in comparison to a shell-type construction. This is of considerable advantage, particularly during a side impact and if the motor vehicle overturns, because of the energy-absorbing effect. Welding flanges are no longer inevitably necessary for production and are no longer of any significance when considering the leakproofness. The absence of gaps and welding flanges means that the hollow profile according to the invention does not allow any leakproofness problems to arise, and it is possible for manufacturing to take place with substantially smaller tolerances than in a multipart shell-type construction. The very great stiffness resulting from the tubular form enables the wall thickness to be reduced with an insignificant reduction in stiffness, which saves structural space and weight. In an advantageous manner with regard to a space-saving and protected possibility of accommodating it, the hollow profile has a receiving housing in which the hinge and/or the gas-filled compression spring is/are fitted. As a blank, the hollow profile may, for example, be an extruded profile or a drawn tube, or may be cut from a billet and welded with a longitudinal seam after a subsequent bending or rolling operation.
In an advantageous development, the hollow profile is held in the hollow space of the roof frame. The shell-type construction then inevitably extends over the entire length of the lateral roof frame. As a result of this, however, the end region has, in conjunction with the held hollow profile, a doubling of the sheet metal, which furnishes the frame with particular stability and stiffness. The hollow profile either can be pushed from the rear with little play into the welded assembly of the shells and then connected to the latter in a suitable manner mechanically, by bonding or welding, or can be tightly encased by the shells of the rear end region of the lateral roof frame, achieving a clamping action. The shells then are welded to one another.
Further expedient refinements of the invention can be gathered from the subclaims; otherwise, the invention is explained in greater detail below with reference to a number of exemplary embodiments illustrated in the drawings.