A head cover structure (45) for an internal combustion engine (1) comprises a head cover (4) connected to a cylinder head (3), and an auxiliary cover (44) connected to the head cover and defining a gas-liquid separation passage (74) jointly with the head cover, the gas-liquid separation passage being communicated with a crankcase chamber (11) of the internal combustion engine, and configured to separate lubricating oil from a crankcase gas drawn from the crankcase chamber, wherein the auxiliary cover is integrally formed with an intake pipe (49) internally defining a part of an intake passage (20) of the internal combustion engine, and the auxiliary cover internally defines a crankcase gas introduction passage (63) communicating the gas-liquid separation passage with an interior of the intake pipe.

A cylindrical part capable of supporting an ignition-coil-integrated plug cap is formed on a head cover so as to correspond to a plug hole of a cylinder head. The cylindrical part is formed by fitting and fixing a pipe material to a mounting hole part formed in the head cover, the mounting hole part facing the plug hole.

A novel cylinder head arrangement for an in-line four cylinder or eight cylinder engine. A modified arrangement allows additional space for installation of wider rocker arm assemblies used for variable valve lift (VVL), cylinder deactivation (CDA) and other types of variable valve actuation (VVA). In one embodiment, cam towers adjacent the end two cylinders are not used. At least one end support is used, which may be an outboard bearing on a camshaft for each end. The wider rocker assemblies may then be installed. In another embodiment, cam towers adjacent the inner two cylinders are eliminated and a single camshaft support piece with a support bearing is installed between the inner cylinders to provide support for the camshafts. The wider rocker assemblies may then be installed on at least one of the middle cylinders. A novel oil control valve operates latches in switching rocker arm assemblies.

A four stroke internal combustion engine is disclosed comprising at least one cylinder arrangement, an exhaust conduit, and at least one turbine. The cylinder arrangement comprises an exhaust port arrangement configured to open and close an exhaust flow area, A.sub.CYL. The cylinder arrangement has a maximum volume, V.sub.MAX. The exhaust conduit extends between the exhaust flow area, A.sub.CYL, and a turbine wheel inlet area, A.sub.TIN, of the turbine and has an exhaust conduit volume, V.sub.EXH that is ≤0.5 times the maximum volume, V.sub.MAX. The exhaust port arrangement is configured to expose the exhaust flow area, A.sub.CYL, at a size of at least 0.22 times the maximum volume, V.sub.MAX, when a piston of the cylinder arrangement is at the bottom dead centre, BDC.

An engine (E) includes a crankcase body (19) including a bottom plate (19a) and a tubular portion (19c), a crankcase cover (20) covering a case opening portion (19b) of the crankcase body (19), a crankshaft (2), a cylinder base portion (21a) located inside the crankcase body (19), a cylinder block (21b) located outside the crankcase body (19), and a camshaft (25) located inside the crankcase body (19) and between the bottom plate (19a) and cylinder base portion (21a). The crankcase body (19) has the bottom plate (19a) detachably attached to the tubular portion (19c).

Systems, devices, and methods are disclosed for supporting one or more camshafts by the engine block in overhead arrangement relative to the cylinder heads and valve train.

An internal combustion engine (1) includes an internal combustion engine main body (20), a head cover (11, 15) attached to an upper end part of the internal combustion engine main body, and an exhaust system (34) connected to the internal combustion engine main body, and a gas-liquid separator (45, 60) for blowby gas provided in the head cover. A part of the exhaust system is positioned adjacent to the internal combustion engine main body in a first direction (X) along a cylinder row, and the gas-liquid separator is positioned in the head cover so as to be offset in the first direction.

A bearing frame or a cylinder head cover for an internal combustion engine may include at least one camshaft mounted in tunnel bearings in at least two bearing openings arranged along a bearing channel and completely enclosing at least one of the camshaft and a radial bearing, and at least one axial shaft bearing ring arranged on the camshaft. The axial shaft bearing ring may have a ring groove which is open towards the bearing frame or towards the cylinder head cover. At least one engagement element may be arranged on the bearing frame or on the cylinder head cover, which engagement element may engage into the ring groove and forms an axial bearing for the camshaft.

A cylinder head cover that prevents the gas outlet for the blow-by gas from being cooled by structural improvements so that the gas outlet does not freeze or become clogged in a cold condition. A cylinder head cover includes: a gas passage through which blow-by gas from a crankcase passes; and a gas outlet portion protruding upward from a head cover upper wall. The gas outlet portion includes a protruding case portion bulging upward from the head cover upper wall so as to form an outlet passage through which blow-by gas passes, and an air layer is formed outside the outlet passage in the protruding case portion.

An internal combustion engine having at least one cylinder bank comprising multiple cylinders, each cylinder comprises a rocker arm box for accommodating rocker arms of a valve train, and each cylinder comprises a rocker arm cover pivotable relative to the rocker arm box. The rocker arm cover carries an ignition coil contactable with a spark plug via an extension extending through a protective tube between the cylinder head and the rocker arm box or the rocker arm cover. The rocker arm cover comprises a first portion with a first introduction aid, into which the protective tube is threaded during closure of the rocker arm cover and a second portion with a second introduction aid, into which the spark plug extension is threaded during closure of the rocker arm cover to automatically and self-centringly form an electrical contact between the spark plug extension and the ignition coil.