Abstract: An engine includes an electric supercharger as a first supercharger, a turbocharger as a second supercharger, a secondary air supply passage, a secondary air valve and a catalyst. The electric supercharger is provided in an intake passage which is in communication with a combustion chamber, and supercharges intake air into the combustion chamber. The turbocharger is provided in the intake passage in series with respect to the electric supercharger, and supercharges intake air to the combustion chamber. The secondary air supply passage and the secondary air valve supply air compressed by the electric supercharger to a discharge passage which is in communication with the combustion chamber. The catalyst is provided in the discharge passage to purify exhaust gas.

Abstract: An engine includes an electric supercharger as a first supercharger, a turbocharger as a second supercharger, a secondary air supply passage, a secondary air valve and a catalyst. The electric supercharger is provided in an intake passage which is in communication with a combustion chamber, and supercharges intake air into the combustion chamber. The turbocharger is provided in the intake passage in series with respect to the electric supercharger, and supercharges intake air to the combustion chamber. The secondary air supply passage and the secondary air valve supply air compressed by the electric supercharger to a discharge passage which is in communication with the combustion chamber. The catalyst is provided in the discharge passage to purify exhaust gas.

Abstract: In a SOHC type internal combustion engine having a single camshaft, a fuel injector is provided for directly injecting a fuel into a combustion chamber, and an intake port is provided such that one end of the intake port is open at intake openings to the combustion chamber. The intake port extends toward the top face of a cylinder head between the camshaft and two intake valves, such that at least a part of the intake port passes through a region between the shortest lines connecting respective head portions of the intake valves and the camshaft.

Abstract: In a SOHC type internal combustion engine having a single camshaft, a fuel injector is provided for directly injecting a fuel into a combustion chamber, and an intake port is provided such that one end of the intake port is open at intake openings to the combustion chamber. The intake port extends toward the top face of a cylinder head between the camshaft and two intake valves, such that at least a part of the intake port passes through a region between the shortest lines connecting respective head portions of the intake valves and the camshaft.

Abstract: In a SOHC type internal combustion engine having a single camshaft, a fuel injector is provided for directly injecting a fuel into a combustion chamber, and an intake port is provided such that one end of the intake port is open at intake openings to the combustion chamber. The intake port extends toward the top face of a cylinder head between the camshaft and two intake valves, such that at least a part of the intake port passes through a region between the shortest lines connecting respective head portions of the intake valves and the camshaft.

Abstract: In a cylinder injection engine which includes an injection valve disposed in the vicinity of an intake port of the engine and adapted to inject fuel into the combustion chamber, a spark plug disposed closer to the center portion of the combustion chamber than the injection valve, and a piston having a cavity formed in the top face that substantially faces the injection valve and the spark plug, the cavity is formed by smoothly connecting a curved surface located below the spark plug and a curved surface located below the injection valve via a connection curved surface. The curvature .kappa..sub.1 of the curved surface located under the injection valve and the curvature .kappa..sub.2 of the curved surface located under the spark plug satisfy a relationship .kappa..sub.1 <.kappa..sub.2.

Abstract: An engine cooling system for inducing a stream of cold air via a radiator fan toward the rear part of a vehicle so as to cool a vehicle engine, which includes catalysts downstream of an exhaust manifold. The radiator fan is displaced in front the engine so that substantially no cold airstreams from the radiator fan directly strike the exhaust manifold. Thus, exhaust emissions are prevented from being excessively cooled, so that the catalysts can become active to purify the exhaust emissions reliably. The engine cooling system is effective to keep the catalysts active when the engine is in the partial cylinder operation mode in which the exhaust emissions tend to be lowered in the temperature.

Abstract: In a valve-moving apparatus for an internal combustion engine, lever members are integrally formed with rocker shaft parts and arm parts, the lever members are provided with large-diameter parts larger in diameter than support parts, disposed between support parts of the rocker shaft parts supported by support members of the engine and the arm parts; rocker arms driven by cams are rotatably supported on the large-diameter parts; and change-over mechanisms for selectively engaging the large-diameter parts and the rocker arms are disposed in the large-diameter parts, thereby improving rigidity of the large-diameter parts and achieving improved reliability of the change-over mechanisms.

Abstract: An internal combustion engine of the present invention comprises at least first and second cylinder banks each including a plurality of cylinders or a single cylinder, a first valve operating mechanism provided for each of the cylinders of the first cylinder bank for operating an intake valve or an exhaust valve of the cylinder to open and close, and a second valve operating mechanism having a valve operating characteristic different from that of the first valve operating mechanism and provided for each of the cylinders of the second cylinder bank for operating an intake valve or an exhaust valve of the cylinder to open and close.

Abstract: In a valve-moving apparatus for an internal combustion engine, lever members are integrally formed with rocker shaft parts and arm parts, the lever members are provided with large-diameter parts larger in diameter than support parts, disposed between support parts of the rocker shaft parts supported by support members of the engine and the arm parts; rocker arms driven by cams are rotatably supported on the large-diameter parts; and change-over mechanisms for selectively engaging the large-diameter parts and the rocker arms are disposed in the large-diameter parts, thereby improving rigidity of the large-diameter parts and achieving improved reliability of the change-over mechanisms.

Abstract: An air diffuser has a non-porous rigid plate mounted on an air chamber to permit diffusion of air to the outside of the chamber, which porous plate has a smooth outer surface and diffusing pores extending therethrough, more than 95% of the diffusing pores having diameters within .+-.20% of a nominal diameter selected in a range of 50-300 .mu.m.