Engine combustion chamber and air intake device

Abstract

A five-valve per cylinder internal combustion engine having a lens shaped combustion chamber that promotes a high compression ratio and which also reduces the likelihood of knocking. The engine includes a cylinder head having three intake valves disposed substantially on one side of a plane containing the cylinder bore axis and a pair of exhaust valves supported for reciprocation on the other side of the plane. The intake valves are disposed at acute angles to a plane containing the cylinder bore axis and containing the axis of rotation of the camshaft. The center of these poppet valves is disposed of on a plane also containing the cylinder bore axis and perpendicular to the first plane, while the remaining intake valves are disposed at opposite acute angles to this plane. The poppet valves are actuated by a camshaft journaled in bearing surfaces formed directly in the cylinder head and through tappets that are supported in bores formed integrally in the cylinder head. The bolting arrangement for the cylinder head and camshaft bearing caps facilitates machining and simplifies assembly. The timing of the drive of the camshaft for operating the intake valves can also be varied relative to the rotational position of the crankshaft so as to reduce or preclude knocking.