Abstract: In an engine block structure in a multi-cylinder engine in which a piston is incorporated from the side of a crank chamber into each of a plurality of cylinders disposed in series in a cylinder block, cylinder axes of the two adjacent cylinders are disposed to extend in such directions that they are gradually spaced apart from each other as proceeding from the side of a valve operating chamber toward the crank chamber as viewed from a direction of arrangement of the cylinders. Thus, a sufficient crankshaft bearing area can be ensured without bringing an increase in number of parts and an increase in size of the engine block.

Abstract: In an engine for a vehicle including a bearing cap integral type oil pan which has a plurality of bearing cap sections integrally provided thereon and which is integrally coupled to a cylinder block, connecting bolts are screwed into the bearing cap sections from the cylinder block to integrally couple the cylinder block and the oil pan to each other. An oil pan chamber, which is an as-cast bore made by drawing a die in an axial direction of a crankshaft, is defined to extend continuously in the axial direction of the crankshaft between the bearing cap sections and a bottom wall of the oil pan. Thus, the oil pan can be produced simply, at a low cost, by a casting process and moreover, it is possible to reduce the weight and size of the oil pan and increase the rigidity of the oil pan.

Abstract: In a wrapping type transmission structure for internal combustion engines, provided with a first wrapping type transmission system which includes a first tensioner urged into press contact with a first endless power-transmitting belt and which is disposed on a side wall of an engine body, and a second wrapping type transmission system which includes a second tensioner urged into press contact with a second endless power-transmitting belt and which is disposed at a location remoter from the engine body than the first wrapping type transmission system, a support shaft is fixed to the engine body and is inserted through the first and second tensioners which are relatively movable in a plane perpendicular to the axis of the support shaft, while permitting the movements of the tensioners in directions of press contact with the first and second transmitting belts. This enables the tensioner arrangement to be compact and permits an increase in freedom for disposition of the transmission systems.

Abstract: An internal combustion engine has a crankcase coupled to a lower end of a cylinder block, the crankcase including an upper case integrally formed with the cylinder block and a lower case fixed to the upper case. The upper and lower cases have a plurality of journal support walls projecting from inner wall surfaces thereof. An oil pan is fixed to the lower open end of the lower case. A crankshaft is rotatably sandwiched by the journal support walls. A breather chamber is mounted on one side of the crankcase and defined by recesses on confronting surfaces of the upper and lower cases, the breather chamber having one end communicating with the crank chamber and an opposite end communicating with an air intake system. At least one balancer shaft is rotatably supported in a balancer chamber mounted on one side of the crankcase. The upper and lower cases define substantially semicylindrical recesses therein which jointly constitute bearings in which the crankshaft and the balancer shaft are rotatably supported.

Abstract: A valve operating mechanism for operating a valve in an internal combustion engine includes a hydraulic lash adjuster for imposing a hydraulic pressure against a cam follower slidably engaging a camshaft. The hydraulic lash adjuster includes a plunger slidably disposed in a cylinder and defining an oil chamber communicating with a pressure chamber between the plunger and the cylinder through a valve hole which can selectively be opened and closed by a free-ball check valve. The plunger is normally urged by a spring to move in a direction out of the cylinder toward the cam follower. The cam follower acts on an end of the valve stem of the valve through an interlink mechanism having an adjusting device for adjusting the volume of the pressure chamber of the hydraulic lash adjuster.

Abstract: An overhead camshaft in an engine is rotatably supported by a camshaft support assembly comprising a plurality of bearing bases, a plurality of cam holders mounted on the bearing bases, respectively, and a rigid frame mounted on the cam holders and interconnecting them. The bearing bases and the cam holders jointly define a plurality of bearing surfaces by which the camshaft is rotatably supported. The cam holders may be integrally interconnected by side walls joined to opposite ends of the cam holders. The rigid frame includes an internal longitudinal oil pipe for ejecting lubricating oil onto cam surfaces of the camshaft. The bearing bases and the rigid frame may be made of an aluminum alloy, whereas the cam holders may be made of cast iron. Each of the cam holders has an oil supply port opening into one of the bearing surfaces at a position such that the lubricating oil will be supplied fully around the journal of the camshaft which is rotatably supported by the bearing surface.

Abstract: An internal combustion engine includes a cylinder head having attachment surfaces which lie in the same plane and to which a head cover and an intake manifold are attached, respectively. The attachment surfaces can therefore be machined simultaneously in one process with a common cutting tool. The internal combustion engine also has a valve operating mechanism housed in a valve mechanism chamber in the cylinder head for actuating intake and exhaust valves. The valve mechanism chamber is defined by a pair of opposite trapezoidal end walls extending from the bottom of the valve mechanism chamber and a ceiling wall integrally interconnecting the upper ends of the trapezoidal end walls. The valve mechanism chamber has a pair of windows defined one on each side of the ceiling wall thereof between the trapezoidal end walls to provide access therethrough to the valve operating mechanism.

Abstract: Oil is supplied from an oil pump as working oil to hydraulic lash adjusters and also as lubricating oil to journals and cams of a camshaft. The oil passage system includes a first supply passage connected to the oil pump, a second supply passage connected between the first supply passage and a first distribution passage coupled to a group of hydraulic lash adjusters, a joint passage connected to the first distribution passage, and a second distribution passage coupled to the joint passage and connected to another group of hydraulic lash adjusters. The second distribution passage is connected by air vent passages to a lubricating oil passage which supplies the camshaft with the lubricating oil. The joint passage is connected to one of the camshaft journals by a relief passage having a relief valve.

Abstract: An oil supply system for the overhead valve actuating mechanism of an internal combustion engine. A cam follower is engaged by a hydraulic tappet for constantly maintaining positive contact among the valve actuating mechanism components including a rocker arm pivotally mounted on a rocker shaft and engaging the end of the valve for opening same and a pusher rod extending between the rocker arm and the cam follower. Oil is supplied under pressure to the hydraulic tappet for operating same and from a reservoir chamber in the tappet through oil passages in the cam follower, pusher rod and rocker arm to lubricate the rocker shaft and the points of engagement between those components.