Abstract: An oil-passage structure of an internal combustion engine which eliminates the necessity of drilling a hole through the chain cover or the tensioner bracket and allows the tensioner bracket to be moved to its proper position according to vehicle layout restrictions, and. maintains optimum functioning of the oil control valve by cooling the oil supplied thereto. The oil-passage structure includes an external oil pipe interconnecting the oil pump and the oil control valve and arranged between the auxiliaries machine driving belt and the chain cover.

Abstract: A blowby gas path structure for an internal combustion engine prevents deterioration in an oil separating function of a breather chamber of a head cover by reducing oil mist conveyed therethrough. The blowby gas path structure includes a plurality of blowby gas paths. The plurality of blowby gas paths have different path sectional areas. Ends of the gas paths are opened to a crank chamber of an internal combustion engine and pass through a cylinder block and a cylinder head. The other ends of the gas paths are opened to a breather chamber of a head cover and open at a communication chamber.

Abstract: A crank chamber structure for an engine which is designed to reduce vibratory noise, to achieve a reduction in weight and cost, and to improve lubricating performance. The crank chamber structure is positioned between a block-side skirt section and a case-side skirt section respectively provided in a cylinder block and a lower case. The skirt sections are curved outwardly to permit the crank chamber to enclose peripheral loci of connecting rods, and further to permit the crank chamber to be formed by a curvilinear surface whose radius is smaller at successively higher positions above the crankshaft axis, thereby providing a substantially egg-like cross-sectional shape. An opening is provided in the lower case by the case-side skirt section being collapsed to taper toward an oil pan-mating surface of the lower case so as to communicate with the oil pan.

Abstract: An improved lubricating oil passage structure for an engine, which includes: a sub-gallery and a main gallery positioned adjacent to one another in a cylinder block; a head-side oil passage and a journal-side oil passage both being communicated to the main gallery and provided in the cylinder block, in which the head-side oil passage is led to an upper surface of the cylinder block, while the journal-side oil passage is inclined so as be oriented toward a journal portion of a crankshaft; a housing-side oil passage communicated to the journal-side oil passage, the housing-side oil passage being provided in a journal housing section of the cylinder block by the use of a spot facing for a housing bolt, the journal housing section supporting the journal portion; a metal-side oil passage communicated to the housing-side oil passage, the metal-side oil passage being provided in the journal housing section at the rear of a journal metal disposed between the journal portion and the journal housing section; and, a cha

Abstract: An oil pump sprocket cover for an internal combustion engine. One side of the oil pump sprocket cover is fixed to the crankcase and the other side of the oil pump sprocket cover is fixed to the oil pump, The oil pump sprocket cover protects the oil pump sprocket, reduces aeration of the oil flowing through the internal combustion engine, and decreases the flow velocity of the oil existing the oil pump sprocket cover thereby reducing oil mist and oil aeration.

Abstract: The weight of the first and fifth counterweights, which are located at opposite ends of a crankshaft, are set to be equal to or smaller than the weight of the remaining second to fourth counterweights. In addition, the thickness of the first and fifth counterweights are set to be equal to or smaller than the thickness of the remaining second to fourth counterweights. Moreover, the first to fifth counterweights are formed generally the same in configuration.

Abstract: An oil pan has a partition for regulating the transverse movement of oil and baffle plates for regulating the vertical movement of oil. The oil pan is divided into an oil pan upper portion and an oil pan lower portion, the oil pan upper portion is formed with a lower portion attaching face on the lower face of an upper-side bottom, a partition for partitioning the oil level is formed by raising a part of the upper-side bottom surrounded by the lower portion attaching face, a first oil chamber is provided on one side of the partition and a second oil chamber is provided on the other side of the partition, attaching bosses are formed at the upper part of the partition to install an upper portion baffle plate, and air holes are formed at the upper part of the partition close to the attaching bosses to provide communication between the first oil chamber and the second oil chamber.

Abstract: An internal chamber of a water pump is extended to a position so as to radially surround at least parts of the water pump bearing and water drain hole. Ribs may be provided in the internal chamber to reinforce the water pump casing.

Abstract: A cylinder head is provided with bolt hole portions for permitting cylinder head bolts to attach the cylinder head to a cylinder block of an engine, and the height of the bearing surfaces of the bolt hole portions is set to a large value so that an oil passage extending in the longitudinal direction of the cam chamber of the engine is provided in the lower portion of the elevated bearing surfaces.