In timing drives of internal combustion engines, such tensioners with a guiding-side guide shoe and a tensioning-side tensioning shoe are used in particular for camshaft-camshaft chain drives. The drive chain connects two juxtaposed camshafts of one cylinder bank, the guide shoe being provided on the driving side, viz. the taut span of the drive chain, and the tensioning shoe on the loose driven side, viz. the slack span of the drive chain, so as to maintain a predetermined chain tension. If, due to wear, the tension of the drive chain changes, a reliable operation of the timing drive of the internal combustion engine requires compensating the chain elongation via the tension of the drive chain in the slack span and maintaining the necessary pretension in the taut span.
A tensioner for a chain drive between two camshafts is known e.g. from U.S. Pat. No. 5,782,625. The chain tensioner shown in this reference comprises a housing as well as a tensioning piston, which is longitudinally movable in a piston bore of the housing and which is provided with a tensioning shoe on its tensioning-side end projecting beyond the piston bore. The tensioner housing is provided with a guide shoe on the guiding side facing away from the tensioning piston and has a fastening flange, which projects laterally from the center of the tensioner housing on one side of the latter and which comprises two fastening apertures and a connection for the hydraulic fluid. This tensioner is secured to the engine block of an internal combustion engine by means of bolts extending through the fastening apertures of the fastening flange. The hydraulic fluid connection provided in the mounting surface establishes a connection to the circuit of the engine oil, which, starting from the hydraulic fluid connection, is fed via a hydraulic fluid line inclined in the direction of the guide shoe, through the fastening flange and into the damping pressure chamber of the tensioner.
Although this tensioner and other tensioners known from the prior art proved to be successful in use, especially when used in timing chain drives of internal combustion engines, there are frequently cases of use which necessitate an adaptation of the structural design or a modified basic concept. It is precisely the compact design of modern, innovative internal combustion engines that necessitates not only a structural adaptation of known tensioners but also completely new concepts for the construction of tensioners in an increasing number of times.
USPTO Backgrounds
USPTO Backgrounds