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 a valve operating system in an internal combustion engine, the operational characteristic of an engine valve which is an intake valve or an exhaust valve can be changed in accordance with the operational state of the engine, the reduction in size thereof can achieved and moreover, the operational characteristic of the engine valve can be finely changed, and the lifted state of the engine valve can be detected simply. A power transmitting device is formed of an inner wheel, an outer wheel and a carrier which rotatably carries a planetary rotor. Among these components forming the power transmitting device, a first component is operatively connected to a cam shaft, and a second component is connected to an engine valve. A rotational amount control device connected to a third component, controls the amount of rotation of the third component in accordance with the operational state of the engine.

Abstract: A valve operating system in an internal combustion engine is disclosed, wherein the operational characteristic of an engine valve which is an intake valve or an exhaust valve, can be changed in accordance with the operational state of the engine. In the valve operating system, a power transmitting means comprises an inner wheel, an outer wheel surrounding the inner wheel, and a carrier on which a planetary rotor is rotatably carried. The inner wheel is operatively connected to a cam shaft, and the outer wheel is connected to the engine valve. A rotational-amount control device is connected to the carrier for controlling the rotational amount of the carrier in accordance with the operational state of the engine. Thus, the size of the valve operating system can be reduced, and moreover, the operational characteristics of the engine valve can be finely changed.

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: A valve operating system includes a connection switch-over device provided in a plurality of cam followers. The connection switch-over device has a piston moved in response to a change in hydraulic pressure in a hydraulic pressure chamber. A roller shaft is disposed on at least one of the cam followers and has a roller carried thereon to come into rolling contact with a valve operating cam. In this valve operating system, the hydraulic pressure chamber and a communication passage, which permits an oil supply passage to communicate with the hydraulic pressure chamber, are defined in a particular one of all the cam followers, which moves a smallest amount when the connection switch-over device is in its disconnecting state. The roller shaft, having the roller rotatably carried thereon, is mounted on the cam follower other than the particular one cam follower.

Abstract: A valve operating mechanism for an internal combustion engine for varying the operation of the valve dependent on engine operating conditions. A first rocker arm movable to follow a first cam and a second rocker arm movable to follow a second cam corresponding to a higher speed operating condition than that of the first cam are pivotally supported on a rocker arm shaft. A first connection switching device capable of switching the connection and disconnection between the third and first rocker arms and a second switching device capable of switching the connection and disconnection between at least one of the first and third rocker arms and the second rocker arm independently from the first connection switching device, are disposed at locations displaced circumferentially relative to the rocker arm shaft.

Abstract: A valve operating mechanism for an internal combustion engine for varying the operation of the valve dependent on engine operating conditions. A first rocker arm movable to follow a first cam and a second rocker arm movable to follow a second cam corresponding to a higher speed operating condition than that of the first cam are pivotally supported on a rocker arm shaft. A first connection switching device capable of switching the connection and disconnection between the third and first rocker arms and a second switching device capable of switching the connection and disconnection between at least one of the first and third rocker arms and the second rocker arm independently from the first connection switching device, are disposed at locations displaced circumferentially relative to the rocker arm shaft.

Abstract: A valve operating mechanism for an internal combustion engine having a pair of intake valves or exhaust valves in each cylinder with a first and a second rocker arm corresponding to the pair of valves and a cam for pivoting the first rocker arm. The rocker arms are provided with a connecting mechanism having a piston assembly which is movable between a position in which both said rocker arms are connected and a position in which both said rocker arms are disconnected from each other whereby either both valves of the pair or only one valve may be selectively actuated. A trigger member in the first rocker arm selectively restricts the movement of the piston and a timing cam engages and actuates the trigger member.

Abstract: An internal combustion engine valve operating mechanism wherein there is a low speed cam corresponding to one intake valve or exhaust valve and having a shape designed for low speed operation as well as a high speed cam of a shape designed for high speed operation. A first rocker arm is in sliding contact with the low speed cam and abuts one intake valve or exhaust valve, a second rocker arm is in sliding contact with the high speed cam and a third rocker arm abuts the other intake valve or exhaust valve, with all three rocker arms pivotably supported by a single rocker shaft adjacent to each other. A first piston for connecting the first and second rocker arms is slidably mounted in the first rocker arm and a second piston for connecting the second and third rocker arms is slidably mounted in the second rocker arm extendable and contractable. A third piston is movably mounted in the third rocker arm and urged by a spring in a direction of abutment with the second piston.

Abstract: An internal combustion engine valve operating mechanism wherein there is a low speed cam corresponding to one intake valve or exhaust valve and having a shape designed for low speed operation as well as a high speed cam of a shape designed for high speed operation. A first rocker arm is in sliding contact with the low speed cam and abuts one intake valve or exhaust valve, a second rocker arm is in sliding contact with the high speed cam and a third rocker arm abuts the other intake valve or exhaust valve, with all three rocker arms pivotably supported by a single rocker shaft adjacent to each other. A first piston for connecting the first and second rocker arms is slidably mounted in the first rocker arm and a second piston for connecting the second and third rocker arms is slidably mounted in the second rocker arm extendable and contractable. A third piston is movably mounted in the third rocker arm and urged by a spring in a direction of abutment with the second piston.