In an internal combustion engine, an oil return passage extending from a breather chamber can be formed without increasing the number of component parts and without increasing the size of the internal combustion engine. The internal combustion engine (1) comprises an engine block (30) defining a cylinder (2); a case member (19) fastened to a lower part of the engine block to define a crank chamber jointly with the engine block; a bearing member (50) fastened to the engine block in the crank chamber to rotatably support a crankshaft; a breather chamber (113) defined in the engine block; an inlet passage (112) formed in the engine block to communicate the crank chamber with the breather chamber; a connection pipe (114) communicating the breather chamber with an intake device; and an oil return passage (150) formed at least in the bearing member, and extending from a bottom part of the breather chamber to an oil return port (147) opening at an outer surface of the bearing member. The oil return port may be provided in a lower part of the bearing member.

In some embodiments, a fuel rail for a two-stroke internal combustion engine includes a fuel rail body, a fuel inlet component integrated within the fuel rail body as a one-piece component and in fluidic contact with a fuel line, one or more fuel exit ports in fluidic contact with a cylinder of a combustion engine, and one or more fasteners adapted to secure the fuel rail body to a cylinder wall of the cylinder of the combustion engine

In some embodiments, a fuel rail for a two-stroke internal combustion engine includes a fuel rail body, a fuel inlet component integrated within the fuel rail body as a one-piece component and in fluidic contact with a fuel line, one or more fuel exit ports in fluidic contact with a cylinder of a combustion engine, and one or more fasteners adapted to secure the fuel rail body to a cylinder wall of the cylinder of the combustion engine.

An internal combustion engine comprises a variable compression ratio mechanism that changes the relative position of a cylinder block with respect to a crankcase and a controlling device that controls the variable compression ratio mechanism. The variable compression ratio mechanism contains a driving device that rotates a shaft that includes an eccentric axis, and the drive device includes a clutch that blocks reverse input and is disposed in a drive power transmission route that transmits the rotational power of a motor to the shaft. The control device fixes the mechanical compression ratio to a predetermined low mechanical compression ratio when the amplitude of the rotational power vibration applied to an output shaft of the clutch is less than a predetermined determination value.

An internal combustion engine with a turbocharger according to an embodiment includes a cylinder block internally including a plurality of cylinders, a cylinder head disposed on top of the cylinder block, and internally including a plurality of exhaust flow passages through which exhaust air discharged from each of the plurality of cylinders flows, and the turbocharger including a rotational shaft, a turbine wheel, and a compressor wheel, the turbine wheel being disposed at one end of the rotational shaft, the compressor wheel being disposed at the other end of the rotational shaft. At least the turbine wheel of the turbocharger is arranged inside the cylinder head. The cylinder head internally includes a plurality of scroll passages for introducing the exhaust air flowing through the plurality of exhaust flow passages to the turbine wheel, the plurality of scroll passages including a first scroll passage for introducing the exhaust air from a first range in a circumferential direction of the turbine wheel to the turbine wheel, and a second scroll passage for introducing the exhaust air from a second range, which is different from the first range in the circumferential direction of the turbine wheel, to the turbine wheel.

An iron-based sprayed coating for coating a bore inner surface of a cylinder block for an internal combustion engine. A coating surface contains pits, its pit amount is within a range of 0.01% to 2.1%, and an average roughness Ra of this coating surface is within a range of 0.01 μm to 0.15 μm. The cylinder block for an internal combustion engine includes a bore having this iron-based sprayed coating on its inner surface, and a cylinder block body having the bore. A sliding mechanism for an internal combustion engine includes this cylinder block for an internal combustion engine and a piston slidable with the bore of this cylinder block. The piston has a piston ring, and the piston ring has a chromium coating, a chromium nitride coating, or a diamond-like carbon coating at a sliding part with the bore.

An engine includes a cylinder, a rocker chamber, an air filter, a crankcase and a rocker chamber cover, wherein the rocker chamber cover is disposed above the cylinder. The engine further includes a cover plate, wherein the cover plate is located at the top of the rocker chamber cover, and the rocker chamber cover and the cover plate are spliced to form a separation cavity and a connection channel. According to the engine provided by the invention, the top structure of the rocker chamber is re-designed and the top space of the rocker chamber is sufficiently used so as to achieve the objects of optimizing a lubricating system and reducing emission, as well as reducing the manufacturing cost and difficulty.

Described is a crankcase and a method for assembling a multi-part crankcase. The method can include providing a cylinder block and a bearing tunnel upper part. The cylinder block has a plurality of threaded holes into each of which a stud screw is screwed, where the stud screws protrude from the cylinder block. The bearing tunnel upper part has a plurality of through-holes, where each of the through-holes is arranged coaxially to a corresponding stud screw. On a side facing the cylinder head, each of the through-holes has an internal thread having a first direction of rotation. A plurality of threaded sleeves, each threaded sleeve has an internal thread that has a second direction of rotation, an external thread that has a first direction of rotation, and a driver profile for inserting a screwdriver tool in a positive-locking manner, are provided.

An engine block has one or more bores configured for receiving one or more respective pistons; one or more coolant passages; and one or more lubricant passages. At least portions of the coolant passages and lubricant passages are disposed adjacent to and about the bores so as to cool the bores. The coolant passage portion extends over a first lengthwise portion of the bores and the lubricant passage portion extending over a second lengthwise portion of the bores. The first and second lengthwise portions are longitudinally spaced apart along the bores.

An internal combustion engine and related components and methods of manufacturing and implementing an internal combustion engine and related components. The internal combustion engine includes a base, a cylinder block mounted onto the base, a cylinder head mounted onto the block, and a structural overhead member mounted onto the cylinder head, such that the cylinder head is positioned between the cylinder block and the structural overhead member. At least one through-bolt positioned in a through-bolt opening, the through-bolt opening extending from the base to the structural overhead member through the cylinder block and the cylinder head to couple the base, the cylinder block, the cylinder head and the structural overhead member together.