A tensioner lever is generally mounted, by means of a mounting bolt or pin, on an engine block or other frame, in the vicinity of a tensioner which cooperates with the lever. The tensioner lever, in cooperation with the tensioner, maintains appropriate tension in the transmission medium to prevent transmission failure due to excess tension and excess loosening of the transmission medium.
In one well-known example of a conventional tensioner lever, described in Japanese Laid-open Patent Publication No. 2001-323976 (pages 1 to 4, FIG. 2), a sliding contact portion extending along the traveling plane of the chain, and a reinforcing body, which reinforces the sliding contact portion, are fused together. In another example of a conventional tensioner lever, described in Japanese Utility Model Registration Publication No. 2540896 (pages 1 to 3, FIG. 1), the lever includes a resin shoe for sliding contact with the transmission chain, and an aluminum arm for supporting the resin shoe.
In the first of the above two conventional chain levers, the reinforcing body is strengthened by glass fibers. As the reinforcing body continues to pivot about a pivoting shaft on an internal combustion engine, the internal surface of its mounting hole is subject to wear, and the glass fibers are exposed and crushed. The crushed glass fibers act as an abrasive, causing accelerated wear and damage to the mounting hole of the reinforcing body and the pivoting shaft. In the case of a lever incorporating an aluminum arm, the continued pivoting of the lever about a pivoting shaft on an engine causes the arm to be burned and thereby also subjected to wear and damage. The use of a bushing or the like, fitted to the pivoting hole, has been considered to avoid the problem of wear. However, this measure increases the number of parts, the difficulty of assembly, and the production cost. Moreover, in the case of an aluminum arm, recycling of a spent lever is troublesome because the resin shoe, the aluminum arm, and a resin pad, must be separated before disposal.
Accordingly, the objects of the invention are to solve the above-described problems, and to provide a tensioner lever having excellent mechanical strength and wear resistance, reduced production cost, reduced weight, and ease of recycling. A particular object of the invention is to reduce wear on the inner circumferential surface and the boss portion of the pivoting hole by which the lever is mounted on the engine block.