Abstract: A valve operating system in an internal combustion engine includes a cam shaft provided with a valve operating cam, a rocker arm having a pair of support wall portions which are integrally connected at their base ends to a swinging support portion swingably supported on a support member mounted on a cylinder head and which are opposed to each other at a distance in a direction along the swinging axis of the swinging support portion, a support shaft supported between the support wall portions, and a roller which is rotatably supported on the support shaft with a bearing interposed therebetween so as to be in rolling contact with the valve operating cam. A lower connecting wall interconnecting lower portions of the base ends of the support wall portions is projectingly provided on the swinging support portion in a manner opposed to an outer peripheral surface of a lower portion of the roller. Thus, it is possible to increase the rigidity of the rocker arm, while avoiding an increase in size of the rocker arm.

Abstract: In a valve operating system for an internal combustion engine comprising a valve-operation driving force transmission means interposed between a valve operating camshaft and an engine valve carried in a body of the internal combustion engine for opening and closing operation of the engine valve, a valve operation mode changeover mechanism capable of switching the opening and closing mode of the engine valve in accordance with the operating condition of the engine, and a wrapping connector type transmission system provided between the valve operating camshaft and a crankshaft, the valve operating system further includes a tension adjusting means capable of adjusting the tension of a transmitting band of the wrapping connector type transmission system, and a control means for controlling the operation of the tension adjusting means in accordance with the operation mode of the valve operation mode changeover mechanism.

Abstract: A material, and a process for producing same, for fabricating components of valve-actuating mechanisms of internal combustion engines, the material comprising an iron-base sintered alloy, which comprises, by weight: 2-7% Cr (chromium); 0.1-1.5% Mo (molybdenum); 0.5-7% W (tungsten); 0.1-3% V (vanadium); and 0.5-3% C (carbon). Upon being subjected to a slide-contact with another member, the material exhibits a high degree of abrasion resistance and at the same time is capable of effectively protecting the material of a member operatively cooperating therewith in slide-contact. The material is thus highly suitable for very frequent slide-contact with a cam member or the like.