A cylinder block includes a support wall part that rotatably supports a crank shaft. The support wall part has a fitting recess part to which a bearing cap can be fitted. In each of the left and right corner parts where a bottom surface and a fitting surface of the fitting recess part intersect, a notch groove is formed that extends in the array direction of cylinder bores and has a substantially arc-shaped cross section when cut by the virtual plane along the extension direction thereof. As a result, stress having a greater value as the location becomes closer to the center part in the extension direction of the notch groove can be substantially uniform in the extension direction of said notch groove, and it is possible to effectively mitigate the stress concentration.

An internal combustion engine includes an engine block, a piston, a cylinder head, and a valve train. The engine block includes a cylinder block including a cylinder bore and a crankcase defining a crankcase chamber with a crankshaft positioned within the crankcase chamber. The piston is coupled to the crankshaft and configured to reciprocate within the cylinder bore. The cylinder head is coupled to the cylinder block. The valve train includes a camshaft, a first and second pushrod, a first and second rocker arm, an exhaust valve housed, and an intake valve. The first rocker arm, the second rocker arm, the exhaust valve, and the intake valve each include at least a layer of a low friction material. The first and second pushrod each pass through a pushrod seal to prevent fluid from reaching the rocker chamber to fluidly isolate the rocker chamber from the crankcase chamber.

An opposed piston engine has a driveshaft with at least one combustion cylinder positioned between opposing, curvilinear shaped cams mounted on the driveshaft, where the center axis of the combustion cylinder is parallel with but spaced apart from the driveshaft axis. A piston assembly is disposed in each end of the cylinder, with one piston assembly engaging one cam and the other piston assembly engaging the other cam. Each piston assembly includes a cam follower that can move along a curvilinear shaped cam to reciprocate the piston assembly within the cylinder. The combustion cylinder includes an intake port in fluid communication with an annular intake channel formed in the engine block in which the cylinder is mounted, and an exhaust port in fluid communication with an annular exhaust channel formed in the engine block.

A combustion engine housing with cylinder cooling includes at least one cylinder. The cylinder cooling channel has a distribution cross-sectional area having a cross-sectional area through which coolant can flow, in a first cross-sectional plane that is perpendicular to the cylinder axis. In a second cross-sectional plane, which is perpendicular to the cylinder axis and which is arranged in relation to the vertical direction between the first cross-sectional plane and the coolant outflow opening, has a throttle cross-sectional area, which is a cross-sectional area through which coolant can flow. The throttle cross-sectional area is smaller than the distribution cross-sectional area.

A method is for generating a cylinder crankcase including a foreign object inclusion for cast reduction and for the improved cleanliness of the generated component. The cast material is in particular removed or pushed from the areas between the tie-rods (2) below the water jacket (1), to avoid dirt input into the component during later engine operation. The areas below the water jacket (1) between the tie-rods (2) are designed as a separate tie-rod core (3), and the bolts (4) used during later installation at the water jacket core (5) are enclosed in the tie-rod core (3), so that the tie-rod core (3) is completely surrounded by cast material in the component following the cast and the bolt (4) has coalesced with the cast, and the tie-rod core (3) remains in the generated component and is located in an encapsulated space generated by the cast material.

To minimize the risk of damaging an internal oil passage for conducting oil, the lower structure of an internal combustion engine includes a bottom wall (6), a side wall (7) provided along a peripheral edge of the bottom wall to define the oil chamber in cooperation with the bottom wall, a device mounting seat (52) provided on the side wall and configure to have a prescribed device (51) attached thereto; and an oil passage portion (57) formed in the side wall to define the oil passage (56), wherein the oil passage opens at the device mounting seat, and a part of the side wall adjacent to the oil passage portion is provided with a load absorbing portion (61) configured to be more readily deformable than the oil passage portion.

A ventilation apparatus of an internal combustion engine of the invention ventilates a chain chamber by recirculating blow-by gas to an intake passage through a blow-by gas recirculation pipe and introducing air into the chain chamber through an air introduction pipe. The air introduction pipe is secured to a head cover wall portion which corresponds to a portion of a head cover wall which defines the chain chamber.

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.

A cylinder block of an engine is provided. The cylinder block includes a cast body defining one or more cylindrical bores. The cylinder block also includes a crankshaft bearing wall formed within the cast body. The crankshaft bearing wall is configured to be removably coupled with a bearing cap to define an opening for rotatably supporting a crankshaft of the engine. The cylinder block further includes a chamfered shoulder portion casted on the crankshaft bearing wall.

A sliding bearing that is disposed in a cylinder block and supports a journal portion of a crankshaft, including: a semi-annular first split bearing having a first circumferential end surface; and a semi-annular second split bearing having a second circumferential end surface. The first and second circumferential end surfaces contact each other, the first split bearing has a same outer diameter as an outer diameter of the second split bearing, the second split bearing has a thickness at a second circumferentially central position that is greater than a thickness of the first split bearing at a first circumferentially central position, the thickness of the first split bearing is decreased from the first circumferentially central position toward the first circumferential end surface, the thickness of the second split bearing is decreased from the second circumferentially central position toward the second circumferential end surface.