The present invention is an internal combustion engine composed of a plurality of cylinders arranged into banks. Located near the mid-point of each bank of cylinders is a section formed with passages that are configured to provide distribution and recovery of cooling and lubrication fluids. This section is located such that the path of these fluids begins and ends at a mid-point so as to provide a shortened path across each half of the bank of cylinders within which the section is located.

An internal combustion engine according to the invention comprises at least two engine blocks which are coupled to one another and each of which includes at least two cylinders, each cylinder being connected to a common drive shaft via a transmission and a clutch. If there is a problem with one engine block, same can be disconnected from the drive shaft so that the engine can continue to operate by means of the other engine block.

A structural frame is provided herein. The structural frame may provide a lubrication passage that feeds a lubricant to a cylinder block. The structural frame may increase cylinder block strength while allowing a cylinder block to be constructed of less material.

An outboard motor comprises an engine block having vertically-aligned first and second banks of cylinders that extend from each other in a V-shape, a vertically-extending central drain passage located below the first bank of cylinders and being configured to drain lubricant to an underlying sump, a vertically-extending crankshaft, and a central deflector located between the first and second banks of cylinders. The central deflector extends from the engine block towards the crankshaft and being configured to deflect lubricant away from the crankshaft to the central drain passage.

Recesses are formed in edge portions of a bearing cap bridge from second fastening portions toward first fastening portions, and when seen in an orthogonal direction to the cylinder block bottom wall, third fastening portions that fasten an engine auxiliary device driven by a crankshaft to the cylinder block bottom wall are arranged in spaces R1 to R4 that are demarcated by first imaginary lines L1, which pass through the second fastening portions and are orthogonal to a crankshaft axial line A, and outlines of the recesses.

An internal combustion engine includes a crankcase that rotatably supports a crankshaft, a case cover that liquid-tightly covers a side of the crankcase, a cylinder block that is joined to the crankcase and divides a plurality of cylinders in a V-type arrangement in which the cylinders are disposed above a virtual horizontal plane including a rotational axis of the crankshaft and intersect each other at a bank angle, a to-be-detected body that rotates integrally with the crankshaft, and a detection sensor that is mounted from the outside on the crankcase at a position higher than the virtual horizontal plane and is made to face a trajectory of the to-be-detected body to generate a pulse signal in response to movement of the to-be-detected body. This provides, in a so-called V-type internal combustion engine, a structure for disposing a detection sensor that can detect the angular velocity of a crankshaft with high precision.

Recesses are formed in edge portions of a bearing cap bridge from second fastening portions toward first fastening portions, and when seen in an orthogonal direction to the cylinder block bottom wall, third fastening portions that fasten an engine auxiliary device driven by a crankshaft to the cylinder block bottom wall are arranged in spaces R1 to R4 that are demarcated by first imaginary lines L1, which pass through the second fastening portions and are orthogonal to a crankshaft axial line A, and outlines of the recesses.

An improved surface activation technique improves the adhesion of thermal spray coatings, which is useful for engine cylinder bores. The new method includes compressing the cylinder bore surface to create a surface profile on the surface, such as through rolling a roller along the surface. An engine block is also provided, which includes a plurality of cylinder bores, each cylinder bore having an inner surface, and each inner surface having a surface profile that includes a helical groove and other surface profiles formed in the inner surface. A thermal spray coating is formed on the inner surface of each cylinder bore, the thermal spray coating being adhered to the surface profile of the inner surface. A roller assembly for activating the surface is also provided.

Provided is a head cover structure of an engine, which is capable of increasing supporting rigidity of a head cover. The engine includes a driving force transmission mechanism for transmitting a driving force of a crankshaft to a valve train, in which on one end side in a cylinder row direction of the head cover, a bulging portion for covering an upper side of the driving force transmission mechanism is provided, and an engine mounting portion is attached to the bulging portion. The bulging portion is provided with an inclined surface portion having an inclined surface inclined downwardly toward the other end side in the cylinder row direction, and the inclined surface is formed to rise upwardly from an intermediate position in the cylinder row direction so as to be continuous with a top surface of the bulging portion on the one end side in the cylinder row direction.

A structural frame is provided. The structural frame includes a bottom surface, first and second cylinder block sidewall engaging surfaces, the first and second cylinder block sidewall engaging surfaces positioned above the bottom surface at a height that is above a centerline of a crankshaft support included in a cylinder block when the structural frame is coupled to the cylinder block.