Abstract: To smoothly perform a shift change by the actuator with a simple structure, a drive motor M as a running drive source is connected with a drive motor electronic motor unit 103 through a FET driver 107. A change motor 61 for driving a shift drum 62 is connected with a change motor electronic control unit 111 through a FET driver 112. When a drive motor electronic control unit 103 outputs the speed change signal on the basis of the detection signal of an accelerator opening sensor 106 and a drive motor rotational speed sensor 104, the output of the driver motor M is temporarily reduced or stopped to release the meshing surface pressure of the gear trains of the transmission T, and during the period thereof, a shift drum 62 is driven by the change motor 61 for performing the shift change. After completion of the shift change, the output of the drive motor M is smoothly increased.

Abstract: Engines having cylinders of noncircular cross section wherein the cylindrical curve is generated at a preselected constant outwardly normal distance from a closed curve. The closed curve is defined as including two spaced points on a major axis of symmetry of the cylinder with two continuously curved portions extending between these points and curved outwardly from the major axis. The closed curve about which the cylinder curve is generated is preferred such that there is a continuous change of curvature without discontinuity in that curvature in the cylindrical curve. The avoidance of discontinuity in the generating curve aids in mass production considerations and cutter life. A plurality of intake and exhaust port arrangements are disclosed illustrating four intake ports and four exhaust ports on opposite sides of the major axis of symmetry of the defined cylinder. In one embodiment, the outermost of the ports are smaller and are positioned closer to the major axis of symmetry.

Abstract: Rocker arm clearance removing device wherein a hydraulic adjuster applies torque to a pressure bearing surface at right angles thereto on a curved outwardly extending pressure bearing arm of an eccentric cam which eccentrically supports the rocker arm. Rotation of the rocker arm resulting from the torque causes the rocker arm to come into pressure contact with a valve operating cam and an intake or exhaust valve. An engaging piece can be provided radially extending from the eccentric cam circumferentially spaced from the pressure bearing arm for engaging a swivel stop on the case of the hydraulic adjuster to limit swinging of the eccentric cam and rocker arm during assembly. An arm stopper can also be provided on the case of the hydraulic adjuster to prevent swinging of cam and rocker arm in the opposite direction during assembly.

Abstract: Intake and exhaust rotary valves (10, 10', 20; 110, 110', 120; 210, 210') are separately disposed in intake and exhaust passages (7, 7', 8, 8'; 107, 108) communicating with a combustion chamber (6; 106) in an internal combustion engine (1; 101), respectively, and are adapted to open and close the corresponding intake and exhaust passages. These rotary valves have spherical valve bodies (13, 13', 23; 113, 113', 123; 213, 213'). A valve operating system (30) for rotatively driving the valve bodies interlockingly with the movement of a piston (5; 105) in the internal combustion engine (1; 101) has drive shaft (34, 36; 134; 234) each of which is connected to the valve body through a connecting member (17, 18; 117, 118; 217, 218). In case a plurality of the intake and exhaust rotary valves are mounted, the valve bodies of the intake rotary valves as well as the valve bodies of the exhaust rotary valves are also interconnected through connecting members.

Abstract: A rotary valve system for an internal combustion engine having ball-type valves with through bores. The valves are driven by rocking cam mechanisms within passageways for controlling communication through intake and exhaust passages. Valve seats are arranged to either side of the valves such that sealing thereof may occur. In one embodiment, side cut portions are employed to allow either intake or exhaust gases to flow around the valve body as well as through the through bore when the valve is in the opening or closing orientation. In another embodiment, a through bore of square cross section is provided to increase flow during opening and closing thereof. In a third embodiment, a bias mechanism is employed to provide torque on the valves and drive mechanism to eliminate clearances such that impact between components will be reduced or eliminated.

Abstract: An internal combustion piston engine having a plurality of intake valves and a plurality of exhaust valves per cylinder employs apparatus for disabling the operation of at least one exhaust valve upon decrease in speed of the engine below a predetermined level.

Abstract: In an internal combustion engine in which intake and exhaust rotary valves each having a spherical valve body are controlled in opening and closing through a valve operating mechanism interlockingly with the movement of a piston, the intake and exhaust rotary valves (10, 20; 110, 120; 210, 220; 310, 310', 320, 320') respectively assume the fully opened positions to open intake and exhaust passages (7, 8; 107, 108; 207, 208; 307, 307', 308, 308'), during the intake and exhaust strokes of the engine (1; 101; 201; 301), and assume the fully closed positions during the explosion stroke. In the fully opened and closed positions, the intake and exhaust rotary valves (10, 20; 110, 120; 210, 220; 310, 310', 320, 320') are held at a stop state for a predetermined period of time by the intermittently operating function of the valve operating mechanism (30; 130; 230; 330).

Abstract: An internal combustion engine includes an engine body having a chamber and an endless transmission member extended around and operatively engaged with a crankshaft and a cam shaft to transmit a rotation of the crankshaft to the cam shaft, the endless transmission member being movable along a closed path of travel in the chamber. A hollow mounting member is disposed in the chamber and has an upper open end and a lower tubular portion. The mounting member is fixed to the engine body through fastening elements secured to an upper portion of a peripheral wall of the mounting member. A tensioner device is disposed in the chamber and includes a tensioner member movably mounted on the engine body, and a hydraulic lock mechanism including a hollow cylinder and a plunger slidably received in the cylinder to define a hydraulic chamber in the cylinder. The cylinder is received in the hollow mounting member and snugly fitted in the lower tubular portion of the mounting member against movement.

Abstract: Engines having cylinders of noncircular cross section wherein the cylindrical curve is generated at a preselected constant outwardly normal distance from a closed curve. The closed curve is defined as including two spaced points on a major axis of symmetry of the cylinder with two continuously curved portions extending between these points and curved outwardly from the major axis. The closed curve about which the cylinder curve is generated is preferred such that there is a continuous change of curvature without discontinuity in that curvature in the cylindrical curve. The avoidance of discontinuity in the generating curve aids in mass production consideration and cutter life. A plurality of intake and exhaust port arrangements are disclosed illustrating four intake ports and four exhaust ports on opposite sides of the major axis of symmetry of the defined cylinder. In one embodiment, the outermost of the ports are smaller and are positioned closer to the major axis of symmetry.

Abstract: An internal combustion piston engine having a plurality of intake valves and a plurality of exhaust valves per cylinder employs apparatus for disabling the operation of at least one exhaust valve upon decrease in speed of the engine below a predetermined level.

Abstract: An apparatus and a method for controlling the operation of intake and exhaust valves of an internal combustion engine having a plurality of intake and exhaust valves for each cylinder to provide an optimum engine output at all operating speeds. When the engine is rotating at a low speed, a part of both of the intake and exhaust valves are rendered inoperative. When the engine is rotating at a medium speed, all of the intake valves are made operative and a part of the exhaust valves are rendered inoperative. Finally, when the engine is rotating at a high speed, all of both of the intake and exhaust valves are rendered operative.

Abstract: A valve actuating apparatus for an internal combustion engine having selectively energizable intake/exhaust valves. Oil is supplied to valve actuators which perform the selective energization of the valve through a spool valve. The spool valve has a bypass for supplying operating oil to the actuators when the spool valve is set to the unenergized position in an amount insufficient for energizing the actuators but sufficient to purge air from the lines connecting the spool valve to the actuators. By so doing, the responsiveness of the actuator system is improved.

Abstract: Herein disclosed is a valve actuating mechanism having a stopping function for use in an internal combustion engine of the type, in which at least one pair of intake or exhaust valves having an identical function and disposed adjacent to each other are arranged for one cylinder. First and second rocker arms respectively having arms abutting against the upper ends of the paired intake or exhaust valves are rockingly supported on a common support shaft which is fixed on the engine body while having an axis perpendicular to the operating directions of the valves. The first rocker arm is formed with a cylinder bore which is opened toward the second rocker arm to bear a plunger therein whereas the second rocker arm is formed with a guide bore which is opened toward the first rocker arm to fit the plunger therein.

Abstract: A valve disabling device for use in an internal combustion engine having inlet valve means, exhaust valve means, at least one of which comprises a plurality of valves. Disabling means selectively holds the at least one of the inlet valve means and the exhaust valve means in a first state wherein part of the valves thereof are inoperative, and in a second state wherein all the valves thereof are operative for alternate closing and opening actions. Transmission state detecting means detects whether power transmission means of the engine is in a connected state wherein power transmission between the engine output shaft and a load on the engine is allowed, and in a disconnected state wherein the power transmission is inhibited.

Abstract: A valve disabling device has an engaging member and an urging member slidably disposed, respectively, in first and second axial bores formed within, respectively, first and second rocker arm means, one of which engages a valve actuating cam. The engaging member is displaceable within the first axial bore by means of pressure applying means, into the second axial bore for driving coupling of the first and second rocker arm means whereby a pair of inlet valves or exhaust valves corresponding to the first and second rocker arm means make valving motions in unison with each other, or out of the second axial bore for disconnection of the first and second rocker arm means from each other to disable part of the valves. Biasing means biases the engaging member into the second axial bore irrespective of operation of the pressure applying means, to correspondingly bias the urging member into a predetermined position where a portion thereof is projected out of the second axial bore.

Abstract: A valve driving control apparatus in an internal combustion engine comprises a plurality of power cylinders each having a plurality of intake and exhaust reciprocating valves which are made operative or inoperative depending upon the load conditions of the engine.This apparatus selectively makes the valves operative or inoperative according to a control signal which is generated in a control circuit in response to the engine rotational speed. A part of the intake valves and a part of the exhaust valves are made inoperative in a low rotational speed range of the internal combustion engine. A part of the intake valves is made inoperative and all of the exhaust valves are made operative in a medium rotational speed range. All of the intake and exhaust valves are made operative in a high rotational speed range.

Abstract: An intake device for an engine including the first intake valve located at the downstream end of the first intake passage that is connected to the primary carburetor. A second intake valve is located at the downstream end of the second intake passage that is connected to the secondary carburetor in a cylinder. Both intake passages are connected to each other through a pathway situated in the middle of said intake passages. A check valve located in said pathway allows flow from the first intake passage to the second intake passage. In accordance with a second embodiment, the primary and secondary carburetors are configured so that operation of the secondary carburetor is a function of negative pressure in the primary system to remain closed under minimal load conditions.

Abstract: An apparatus and a method for controlling the operation of intake and exhaust valves of an internal combustion engine having a plurality of intake and exhaust valves for each cylinder to provide an optimum engine output at all operating speeds. When the engine is rotating at a low speed, a part of both of the intake and exhaust valves are rendered inoperative. When the engine is rotating at a medium speed, all of the intake valves are made operative and a part of the exhaust valves are rendered inoperative. Finally, when the engine is rotating at a high speed, all of both of the intake and exhaust valves are rendered operative.

Abstract: A valve .[.disabling.]. .Iadd.operation control .Iaddend.device for use in an internal combustion engine having inlet valve means, exhaust valve means, at least one of which comprises a plurality of valves. Disabling means selectively holds the at least one of the inlet valve means and the exhaust valve means in a first state wherein part of the valves thereof are inoperative, and in a second state wherein all the valves thereof are operative for alternate closing and opening actions. Transmission state detecting means detects whether power transmission means of the engine is in a connected state wherein power transmission between the engine output shaft and a load on the engine is allowed, and is a disconnected state wherein the power transmission is inhibited.

Abstract: Herein disclosed is a valve actuating mechanism having a stopping function for use in an internal combustion engine of the type, in which at least one pair of intake or exhaust valves having an identical function and disposed adjacent to each other are arranged for one cylinder. First and second rocker arms respectively having arms abutting against the upper ends of the paired intake or exhaust valves are rockingly supported on a common support shaft which is fixed on the engine body while having an axis perpendicular to the operating directions of the valves. The first rocker arm is formed with a cylinder bore which is opened toward the second rocker arm to bear a plunger therein whereas the second rocker arm is formed with a guide bore which is opened toward the first rocker arm to fit the plunger therein.