Abstract:
A sustainer for securing a roof rail to a vehicle surface, which does not require protrusions or bumps to be formed on the vehicle surface to prevent unwanted rotation of the sustainer during tightening of an external bolt onto the sustainer.

Description:
TECHNICAL FIELD 
     The invention relates to a sustainer for a vehicle roof rail, and more particularly to a sustainer that is self-adjusting and does not require protrusions or bumps to be formed in the roof surface of a vehicle to assist in holding the sustainer stationary during assembly to the vehicle roof. 
     BACKGROUND OF THE INVENTION 
     A generic sustainer is shown in EP0780267A1. This known sustainer features a fastening bolt with a first threaded portion and a second threaded portion running in the opposite direction to the first. A support part, which separates the threaded portions from each other, is located between the threaded portions. 
     During assembly, the support part comes to rest on a support sheet upon which rib-shaped bumps have been molded. The bumps are supposed to prevent the fastening bolt from rotating further than desired while a nut is being screwed on. 
     A disadvantage of this known sustainer is the unavoidably necessary manipulation on the vehicle&#39;s roof (i.e., on the roof panel or on the floor of a roof channel) for the purpose of molding rib-shaped bumps. It has been shown in practice that automobile manufacturers strongly resist forming such bumps or protrusions during manufacture of the vehicle. 
     SUMMARY OF THE INVENTION 
     It is the objective of the present invention to provide automatic compensation for tolerances between a sustainer and a roof, or a roof channel, without the need for additional steps of forming rib-shaped bumps on the roof to assist in securing the sustainer to the roof. 
     The sustainer of the present invention comprises a fastening bolt assembly having a fastening bolt. The fastening bolt has a head portion and a shank. The head portion includes a first threaded portion and the shank portion includes a second threaded portion. The second threaded portion is formed with its threads opposite to the first threaded portion. The head portion also includes a through bore within which is disposed a spring positioned inbetween opposing blocking elements. A pair of channels are also formed in the head portion which each receive moveable pins. The head portion is screwed into a journal piece of a roof rail prior to fastening of the roof rail to the vehicle roof. 
     During assembly, when a nut is tightened onto the shank of the fastening bolt, this causes the head portion to be unscrewed from the journal piece. As this occurs, the pins move into positions whereby the blocking elements are able to extend through openings formed in each of the pins, and into integrally formed structure on the journal piece. This prevents further rotation of the fastening bolt as the nut is tightened further onto the shank. 
     The present invention accomplishes self-adjustment of the sustainer and prevents unwanted rotation of the fastening bolt relative to the journal without requiring special surface projections to be formed on the vehicle roof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various advantages of the present invention will become apparent to one skilled in the art by reading the following specification and subjoined claims and by referencing the following drawings in which: 
     FIG. 1 is an exploded perspective view of the fastening bolt assembly forming a sustainer in accordance with a preferred embodiment of the present invention; 
     FIG. 2 is a side cross-section view of the fastening bolt assembly of FIG. 1 placed in position ready to secure a journal piece of a roof rail to the roof of the vehicle; and 
     FIG. 3 illustrates the fastening bolt assembly in a fully secured position relative to the vehicle roof. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a fastening bolt assembly  1  in accordance with a preferred embodiment of the present invention, which is designed as a tolerance compensator for a sustainer of a roof rail (not shown). The fastening bolt assembly  1  contains a bolt  1   a  having a cylindrical bolt head  2  and a cylindrical bolt shank  4 . The shank  4  is offset from the bolt head  2  by a step  3 , whose diameter is substantially smaller than that of the bolt head  2 . Bolt head  2  features a left-handed thread and bolt shank  4  a right-handed thread. 
     Bolt head  2  features a cross hole or bore  5 , which is designed as a through-hole, and which is used to accommodate two blocking elements  6  and a spring  7  installed between them. The spring is preferably a compression spring. The bolt head  2  also features two channels or bores  8  passing axially therethrough which each intersect the cross bore  5 . The bores  8  each are used to accommodate one pin  9  in each. 
     The bores  8  can be designed closed, as illustrated, or also could be formed as channels that open on the rim and be undercut at the same time, if necessary. Each bore  8  features a cross-sectional opening that is matched to the cross sectional shape of the pins  9 , such as square, rectangular, or even rounded shapes. The pins  9  are detachably fastened within the bores  8 , preferably by an adhesive bond. The pins  9  each feature an opening  10  that is shaped strongly conical. A washer  11 , which can be milled from a steel part or cast out of various materials, is also preferably part of the fastening bolt assembly  1 . 
     Referring to FIG. 2, when a roof rail is delivered, each sustainer, respectively, is equipped with a fastening bolt assembly  1  which serves as a tolerance compensator at the same time. In this regard, the bolt head  2  is located within a tapped hole of a journal piece  12  of the roof rail. Bolt head  2  is screwed sufficiently far into the tapped hole so that the step  3  and the open end of journal piece  12  are at approximately the same height. The pins  9 , which are detachably fastened within the channels  8  preferably via adhesives, are located in a position in which they protrude over the open end of the journal piece  12  on the one hand and on the other hand prevent the blocking elements  6  from coming out of the cross bore  5 . 
     The actual fastening process can be executed according to the fitting arrangement shown in FIGS. 2 and 3, wherein a fixing nut  15  (FIG. 3) is screwed onto bolt shank  4 . When the fixing nut  15  is being screwed on, the bolt head  2  is forced to unscrew itself downwards out of the left-handed thread of the journal piece  12  because of the small degree of friction between it and the thread of the journal piece. During this process, the fastening of pins  9  becomes detached because the relatively weak adhesive bond tears. By additional rotation of the fixing nut  15  in the tightening direction, bolt head  2  continues to be unscrewed out of journal piece  12  until the step  3  abuts the washer  11 . In this position of assembly, the blocking elements  6 , which each feature a conical tip, are pressed through the openings  10  of the pins  9  and out of the cross bore  5 , as a consequence of the prestressing force of the spring  7  acting upon them. The blocking elements  6  are urged against the wall of the tapped hole of journal piece  12 . Since this wall features several longitudinal slots  16  distributed over the perimeter, the fastening bolt  1   a  will only continue to rotate until the blocking elements  6  each engage one of the longitudinal slots  16  and lock the bolt head  2  into position with the journal piece  12 . At this point, the screw connection can then be tightened fully and the roof  14  can be braced between the step  3 , the washer  11 , and the fixing nut  15 . 
     FIG. 2 shows the delivery state as well as the start of assembly. The bolt shank  4  passes through the washer  11  and an opening  13  in the vehicle&#39;s roof  14 . he washer  11  rests on the roof  14  and supports the open end of the pins  9 . The term “roof” should also be understood to encompass the floor of a roof channel designed within a vehicle roof. 
     The actual fastening process can be executed according to the fitting arrangement shown in FIGS. 2 and 3, wherein a fixing nut  15  (FIG. 3) is screwed onto bolt shank  4 . When the fixing nut  15  is being screwed on, the bolt head  2  is forced to unscrew itself downwards out of the left-handed thread of the journal piece  12 . During this process, the fastening of pins  9  becomes detached because the relatively weak adhesive bond tears. By additional rotation of the fixing nut  15  in the tightening direction, bolt head  2  continues to be unscrewed out of journal piece  12  until the step  3  abuts the washer  11 . In this position of assembly, the blocking elements  6 , which each feature a conical tip, are pressed through the openings  10  of the pins  9  and out of the cross bore  5 , as a consequence of the prestressing force of the spring  7  acting upon them. The blocking elements  6  are urged against the wall of the tapped hole of journal piece  12 . Since this wall features several longitudinal slots  16  distributed over the perimeter, the fastening bolt  1   a  will only continue to rotate until the blocking elements  6  each engage one of the longitudinal slots  16  and lock the bolt head  2  into position with the journal piece  12 . At this point, the screw connection can then be tightened fully and the roof  14  can be braced between the step  3 , the washer  11 , and the fixing nut  15 . 
     The position of the openings  10  in the pins  9  define the path that can still be reached after everything is locked into position, and that can be used for pressing a conventional base, not depicted here, that is installed between the sustainer and the roof  14 . The gap arising between the sustainer and the roof panel can largely be kept constant by the described measures. In particular, the described system is assembly-friendly and insensitive to its own and external tolerances. 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification and following claims.