In technology, a large number of tensioning or guide rails is used for internal combustion engines, in particular for timing drives. In this field of use, high demands have to be satisfied with respect to the strength of the rails as well as the sliding and guiding characteristics in the area of contact with the flexible, endlessly circulating drive means of the timing drive. The endless drive means must be kept under a defined tension during operation. At the same time, tolerances and elongations of the drive means resulting from the respective operating conditions must be compensated for in the timing drive. Therefore, tensioning or guide rails are normally configured as bipartite elements comprising a supporting body and a sliding body arranged on the supporting body. The supporting body is often provided with a truss structure, which improves the strength of the rails, and is manufactured as a die-cast aluminum profile or a fiber-reinforced plastic profile. Due to the different demands that have to be satisfied by the sliding surface of the sliding body for contact with the endless drive means, the sliding body is produced from a different material in a separate production step, said material having the desired sliding and guiding characteristics for pressure contact with an endless drive means. For reasons of wear, the sliding body may also be configured such that it can be exchanged.
DE 296 02 917 U1 discloses a tensioning or guide rail for a timing chain drive, comprising a supporting body made of filled or fiber-reinforced plastics and a sliding body made of low-friction plastics. The supporting body and the sliding body are produced separately of one another as prefabricated structural units. During final assembly, the sliding body is mechanically connected to the supporting body by means of form-fit elements on the lower side of the sliding lining carrier, said supporting body having appropriate cutouts for receiving the form-fit elements therein.
Another tensioning or guide rail is described in DE 43 103 06 A1. Also in the case of these rails, the supporting body is produced from fiber-reinforced plastics by means of an injection molding process. For connecting the sliding body including the sliding surface, the bearing surface of the body has formed therein undercut grooves which extend over the entire length of the supporting body. For attaching the sliding body, said supporting body is placed in a mold, in which the sliding body is injection molded onto the prefabricated supporting body. By means of the undercut grooves, a very strong bond is accomplished between the supporting body and the sliding body, which can, however, no longer be released. Since this manufacturing method is very work-intensive and the supporting body must be positioned precisely so that the sliding body can be connected thereto by injection molding, this manufacturing method is, in total, very cost-intensive.
Although many of the tensioning and guide rail structural designs known in the prior art proved to be very useful in practice, it is, due to the general pressure for innovations in the field of automotive industry, constantly endeavored to improve structural designs and to adapt them to the increasing demands. In addition, tensioning or guide rails are mass-produced articles which, with respect to the high numbers of pieces involved, constantly necessitate that the structural designs used are replaced by less expensive or synergetic concepts.
USPTO Backgrounds
USPTO Backgrounds