Yamaha Hatsudoki Kabushiki Kaisha

Yuji Saiki

Naoki Tsuchida

Mitsuo Tsuchiya

Kengo Nishi

Toshiyuki Takahashi

Matsunori Narita

An improved cam and follower arrangement suitable for actuating, for example, poppet valves of an internal combustion engine and method and apparatus for forming the cam surface. This permits the use of skewed valve axes without using multiple rocker arms for each valve. The shapes are chosen and formed to provide better contact area and permits the cams to be ground with conventional grinding methods and for multi-cylinder engines.

Three dimensional cam, grinding method and grinding apparatus

A multi-valve internal combustion engine having a plurality of valves having skewed axes that are operated by cam lobes of a single cam shaft. The cam shaft operates the valves through rocker arms each of which are pivoted independently about axes that are skewed relative to the cam shaft axis so as to minimize bending stresses on the valve during its actuation. This also avoids scuffing between the rocker and the valve stem. At the same time, good contact is maintained between the cam lobe and the follower surface by machining the cam lobe so that it will have a slight concavity at least in its tip portion so as to ensure constant line contact with the follower.

Method of forming a camshaft for an engine

Valve operating system for engine

In a valve drive system, a plurality of intake or exhaust valves are disposed radially in a cylinder, and the intake or exhaust valves each are driven by respective rocker arms supported for rotation on a cylinder head via a rocker pin and an intake or exhaust cam shaft having three-dimensional cams for engaging these rocker arms. A boss of the rocker arm is coupled to the rocker pin for tilting movement in a direction perpendicular to the axis of the rocker pin. The rocker arm is tiltable with respect to the rocker pin to follow the three-dimensional cam surface. The cam surface can be in line contact with the sliding surface of the rocker arm throughout its circumference.

Valve drive system for engines

In a valve drive system, a plurality of valves are disposed in skewed relation to a cylinder. The valves each are driven by respective rocker arms supported for rotation on a cylinder head via respective rocker pins and cam shafts having three-dimensional cams for engaging these rocker arms. The rocker pins are individually supported on the cylinder head between the cam shafts.

Growing community of inventors

Iwata, Japan

Yuji Saiki