Abstract: Several embodiments of internal combustion engines having at least five valves, three intake and two exhaust, all operated by a single camshaft. The intake valves are disposed so as to provide a smooth combustion chamber configuration by minimizing the difference in angle between the valves and the valves and rocker arms are arranged so that different degree of lift may be provided. One rocker arm operates one valve and another rocker arm operates two valves with the two valves being operated being differently configured so as to provide the desired different lift. In addition, a staged intake system is included that has a single intake passage that extends perpendicular to a plane containing the cylinder bore axis and serving one intake valve and a siamese intake passage serving the other intake valves. The siamese intake passage has a section that extends also perpendicularly to the plane.

Abstract: The invention relates to an internal combustion engine comprising an inlet manifold, at least one combustion chamber with at least two inlet valves and at least one outlet valve, a piston reciprocable in the or each chamber to define a variable volume space therein, and means for controlling the timing of the opening and closing of each of two of the inlet valves of the or each chamber independently so that opening of one of the independently controlled inlet valves of the or each chamber occurs during the exhaust stroke of the engine, opening of the other of the independently controlled inlet valves of the or each chamber, at a time when said one of the independently controlled inlet valves is closed, and when pressure in the or each chamber is lower than pressure in said inlet manifold, producing a predetermined pressure differential across said other of the independently controlled inlet valves, creating an in-flow to the or each chamber generating turbulence, at least some of which is present when combust

Abstract: An internal combustion engine of the type having a fuel injection valve provided with assist air supply device for finely atomizing fuel and disposed in an intermediate portion of the intake passage, and swirl control device for producing a swirl in the combustion chamber in accordance with an operational condition of the engine, which engine is capable of conducting a lean burn. The engine further includes a control unit for controlling the operation of the assist air supply device in accordance with the operational conditions of the engine including at least the temperature of the engine cooling water, the operational condition of the swirl control device, and the condition whether the engine is in the range of the lean burn to thereby improve the operaation of engine under various conditions.

Abstract: In an internal combustion engine comprising a valve operating system connected to a pair of intake valves and arranged to open one of the intake valves only in a very small amount such that the one intake valve is brought into its substantially inoperative state, in a suction stroke mainly in a low speed rotation region of the engine, a fuel injection valve capable of injecting fuel toward a pair of intake ports independently corresponding to the intake valves, and a control means for controlling the operation of the fuel injection valve, the control means is arranged to control the fuel injection valve with a fuel injection completion time determined within a suction stroke, when the one intake valve is in the substantially inoperative state.

Abstract: A valve operating system in an overhead cam type multicylinder internal combustion engine having three intake-side rocker arms disposed to operate a pair of intake valves and two exhaust-side rocker arms disposed to operate a pair of exhaust valves. The intake-side rocker arms are provided with a connection switchover mechanism capable of switching-over the connection and disconnection of the adjacent in take-side rocker arms. Exhaust-side cams are provided on a cam shaft on opposite sides of intake-side cams which are provided adjacent one another. Two of the intake-side rocker arms and both of the exhaust-side rocker arms are in rolling contact with the corresponding cams through rollers mounted on the rocker arms. The exhaust-side a rocker arms are provided with notches in the area near the cam shaft for accommodating portions of the intake-side rocker arms, respectively.

Abstract: Multiple intake valves operatively associated in a common combustion chamber are advantageous in that the design achieves high output for an internal combustion engine. The subject modified cylinder head utilizes the advantages available in a multiple intake valve system, but further enhances the design by reducing heat rejection. In the subject modified cylinder head, three intake valves (38,40,42) having corresponding intake valve ports (26,28,30) and one exhaust valve (68) having an exhaust valve port (66) are operatively associated in a common combustion chamber. A reduction in heat rejection is achieved through a relationship between the cross-sectional areas of the intake and exhaust valve ports (26,28,30,66). The intake valve ports (26,28,30) are constructed so that their cross-sectional area is larger than about 69% of the combined cross-sectional area of the intake and the exhaust ports (26,28,30,66).

Abstract: A motorcycle powered by a fuel injected four cycle internal combustion engine having three valves per cylinder served by a Siamese type intake port arrangement. The centers of the inlet openings of the intake ports are offset from the center of the center intake port served thereby and a single fuel injector is disposed for spraying fuel into each of the intake openings so that all ports will receive equal amounts of fuel and so that the fuel injectors are disposed in parallel relationship to permit a single fuel rail to supply fuel to all of the fuel injectors.

Abstract: An internal combustion engine is described as having a unique angular relationship between the longitudinal axis of each piston cylinder, the center axis of any associated intake ports through which fluid enters the cylinder, and the longitudinal axis of any associated intake passageway for channeling fluid to the communicating intake port, to induce the fluid entering the cylinder to swirl about an axis which is angularly disposed to the longitudinal axis of the cylinder, rather than conventionally swirling about the longitudinal axis of the cylinder. The initial velocity of swirl is then accelerated by the principle of conservation of angular momentum to a more rapid and robust velocity during the compression stroke, thereby allowing the use of a much leaner fuel to air mixture.

Abstract: A number of embodiments of these valve intake systems for internal combustion engines served by a siamese type intake passage and configured to generate a swirl in the intake charge. A single fuel injector sprays fuel into a common inlet opening of the siamese intake passage and sprays more fuel toward the swirl side port so as to insure equal flow through all of the ports.

Abstract: A diesel engine includes a variable swirl forming mechanism, an exhaust gas recirculation (EGR) control mechanism, and an injection timing control mechanism. The variable swirl forming mechanism forms strong, middle or weak air swirls in a combustion chamber according to engine loads and engine speeds. The EGR control mechanism recirculates a part of exhaust gas to the combustion chamber according to the engine loads and the engine speeds. The injection timing control mechanism advances or retards the injection timing according to the engine loads and the engine speeds.

Abstract: A timing system, in particular for high performance internal combustion engines, having five or more valves per cylinder, is described. Three identical valves serving a given cylinder of an engine are controlled by a single camshaft by means of a pair of corresponding cams which act together with a pair of tappets which are mounted slidably in corresponding guides in the cylinder head. The tappets act together at the edges with corresponding valve stems of the three valves which are slidably mounted within second guides within the cylinder head, against the force of corresponding elastic means in a radially eccentric position with respect to the axis of the tappets in such a way that the valve stem of the intermediate valve acts simultaneously with both tappets, while the valve stems of the two lateral valves each act together with a corresponding different tappet in positions of mirror-image symmetry with respect to the center plane of the cylinder passing through the axis of the intermediate valve.

Abstract: An internal combustion engine having an assist air supply device for finely dividing injected fuel and an exhaust gas recirculation device for selectively circulating an exhaust gas from an exhaust passage into an air intake passage. In this internal combustion engine, a swirl operation for a lean burn during a low load on the engine and a non-swirl operation for a burn based on a theoretical air-fuel ratio can be selectively switched between such operations. In the non-swirl operation, the supply of an assist air and the recirculation of a large amount of an exhaust gas are carried out. This makes it possible to reduce both specific consumption of fuel and the amount of NO.sub.x in the exhaust gas over the entire operational region of the engine.

Abstract: An air intake system for a fuel injection engine having cylinders equipped with a swirl port and a conventional straight port. The air intake system comprises a swirl control valve for opening or closing the inlet air passage to the straight port, and further comprises an adapter piece installed in the division wall separating the inlet air passages into the swirl port and the straight port. An aperture communicating both inlet air passages is formed in the adapter piece, and the size thereof is optimized in consideration of the size of an air induction hole disposed in the swirl control valve, to thereby obtain a larger operation area of the air fuel ratio of the lean air fuel mixture supplied to the engine.

Abstract: The inlet arrangement comprises two inlet ports for a fuel and air mixture each of which terminates at an orifice openable and closeable by a respective valve. Each inlet port is of a high flow/low swirl type and a mixture of fuel and air which flows through the orifice can be deflected to enable the inlet port to perform as a low flow/high swirl at smaller throttle openings. In one embodiment, flow of mixture through the inlet port can be deflected at low throttle openings by a transverse flow of gas from inlet ducts. In other embodiments, the direction of mixture flow can be varied by members movable into and out of the mixture flow.

Abstract: This invention concerns a fuel injector for an engine having a combustion chamber provided with a plurality of intake ports, an intake manifold connected to these ports via a branch, intake valves which open and close the ports, and stems passing through the ports which support the intake valves. A fuel injector body is provided upstream of the branch, and the fuel delivered by this body is ejected near the valve stems of the intake ports via a guide pipe which is branched at its end. The openings in the ends of the guide pipe are preferably situated on the side of the center of the combustion chamber, and inject fuel only when the intake valves are open. A mixing mechanism may also be provided to mix fuel and air in the body of the fuel injector. The ends of the guide pipe may also be further branched toward respectively the center and the outside of the combustion chamber.

Abstract: In a direct injection diesel engine provided with a fuel injector facing the center of the combustion chamber, a fuel injection pump supplying high pressure fuel to said injector, two air intake ports and two exhaust ports disposed in apposition to one another around said injector as center, air intake valves and exhaust valves which open and close these ports in synchronization with the engine, a swirl control valve installed in one air intake port, and a control means which adjusts the aperture of said control valve depending on the fuel injection pressure, the swirl control valve shuts when the fuel injection pressure is low so as to enhance the swirl of intake air. This promotes conversion of fuel to fine droplets, uses air more efficiently in the combustion and thereby reduces smoke generation. On the other hand, when the injection pressure is high, the swirl control valve opens which increases the charging efficiency and makes it possible to withdraw high power from the engine.

Abstract: An air-fuel ratio control device for an engine, by which the air-fuel ratio of the air-fuel mixture supplied to the engine is changed. The device set the air-fuel ratio to a lean mixture when the engine load is lower than a set load value and predetermined set speed, and when the engine load become higher than the set load value, or the engine speed exceeds the set speed, the device switches the air-fuel ratio from a lean mixture to a rich mixture to obtain higher engine output. The set load value is varied in accordance with the engine speed such that it is reduced as the engine speed is increased.

Abstract: A multi-valve internal combustion engine has a plurality of intake valves, and the same number of intake ports as there are intake valves, for each engine cylinder. One of the intake ports forms a helical passage, opening into a center of a combustion chamber of the engine at the location of a spark plug, which is disposed adjacent an intake valve located in the center intake port. In addition to a fuel injector disposed in one of the intake ports, a secondary fuel injector, energized so as to inject fuel when the engine operates at lower loads, is preferably disposed adjacent the intake valve located in the one intake port.

Abstract: In an internal combustion engine with two or more inlet valves for each engine cylinder and roof-shaped boundary surfaces of the combustion chamber in the cylinder head--the main flow directions of the partial streams admitted into the combustion chamber by the inlet valves each forming an acute angle with the plane defined by the cylinder axes of a cylinder bank, i.e., the symmetry plane--, a strong torque of the charge in the combustion chamber is obtained at partial load without impairing the intake of charge at full load due to a deterioration of flow characteristics, by providing that the angle of at least one partial stream on one side of a plane going through the cylinder axis and being normal to the symmetry plane, be made larger by 10 to 40 degrees than the angle of at least one corresponding partial stream on the other side of this normal plane.

Abstract: An intake duct in a cylinder head of an internal-combustion engine has a defined flow profile by which the flow rate of the gas flow is accelerated continuously, specifically up to a first intake duct segment of the intake duct which, as viewed in the flow direction, is situated in front of the valve stem. Subsequently, in a second intake duct segment, the flow rate of the gas flow is reduced continuously, whereby a lower approach flow rate of the valve is achieved. This results in an optimized volumetric efficiency which has a favorable influence on the performance and consumption of the internal-combustion engine.

Abstract: A method for controlling a spark-ignition engine without a throttle flap is carried out with variable inlet valve opening durations. The method includes the steps of: detecting a speed signal having a value dependent upon the engine speed; detecting an accelerator pedal signal having a value dependent upon the accelerator pedal position; determining the intake valve opening durations as well as the fuel quantity in dependence upon the particular values of the engine speed signal and the accelerator pedal signal; and, determining the ignition angle in the dependence upon the particular values of the engine speed and fuel quantities. The method affords the advantage that for all driving conditions and even for sudden changes of the accelerator pedal signal, the masses of air and fuel are optimally adapted to each other in order to obtain high driving comfort without misfirings and with low toxic gas exhaust.

Abstract: An SOHC type internal combustion engine comprises a pair of intake valves and a pair of exhaust valves, which are carried in a cylinder head, for opening and closing operation, at a small angle formed by axes of both the pairs of the valves in a projected view on a plane perpendicular to a crankshaft axis including an axis of a cylinder, a single cam shaft rotatably disposed above a combustion chamber, a single rocker shaft fixedly disposed above the combustion chamber, a plurality of intake rocker arms interposed between the cam shaft and the pair of intake valves and swingably carried on the rocker shaft, a pair of exhaust rocker arms interposed between the rocker shaft and the pair of exhaust valves and swingably carried on the rocker shaft, and a plug insertion cylindrical portion which is provided in the cylinder head between both the exhaust valves and into which is inserted a spark plug disposed at a substantially central portion of a ceiling surface of the combustion chamber.

Abstract: A SOHC type internal combustion engine includes a pair of intake valves and a pair of exhaust valves. The intake valve driving means comprises a plurality of rocker arms disposed adjacent one another, including a pair of driving rocker arms operatively connected separately to the intake valves and a connection switchover mechanism capable of switching-over the connection and disconnection of the adjacent rocker arms in accordance with the operational condition of the engine. The exhaust valve driving means comprises a pair of exhaust valve-side rocker arms operatively connected separately to the exhaust valves and disposed on opposite sides of the intake valve driving means in positions opposed to said cam shaft, respectively. In the intake valve driving means, the opening and closing mode of the intake valves can be changed in accordance with the operational condition of the engine by operation of the connection switchover mechanism, thereby providing an improvement in output from the engine.

Abstract: A timing system for controlling, by means of a single overhead camshaft, three adjacent, homologous valves of an internal combustion engine cylinder; each valve having a tappet located between the valve stem and a respective control cam on the camshaft. The valve stems are arranged with their axes shifted laterally, and alternately on opposite sides, in relation to a plane including the axes of the tappets, so as to define a first eccentricity between each valve stem and respective tappet in a plane perpendicular to the camshaft axis. The intermediate valve item is aligned with the axis of the respective tappet in the first plane. In a plane perpendicular to the above plane the other two valve stems are both shifted laterally towards the intermediate valve stem, so as to define, with the respective tappets, a second eccentricity perpendicular to the first. The tappets may thus be arranged side by side and aligned centrally along the camshaft axis.

Abstract: A timing system for controlling, via a single overhead camshaft, three or more valves of an internal combustion engine cylinder, each valve presenting a tappet located between each valve stem and a respective cam on the camshaft. The tappet axes are shifted laterally on alternate opposite sides in relation to the axes of the respective valve stems, so as to define a first predetermined eccentricity between the valve stem axes and the axis of each tappet. Moreover, the axis of each tappet is arranged eccentrically in relation to the rotation axis of the camshaft on the valve stem side, so as to define a second predetermined eccentricity in relation to the camshaft axis.

Abstract: An intake system of an internal combustion engine includes first and second intake valve openings provided in the engine body and exposed to a combustion chamber, first and second intake valves in the engine body for opening and closing the valve openings, respectively, and a valve operating system connected to the intake valves for changing the modes of operation of the valves in compliance with the operation of the engine, wherein the engine body is provided with a swirl producing intake port leading to the first intake valve opening and a substantially linear main intake port leading to the second intake valve opening, and wherein the valve operating system is capable of changing over between a state meeting a low speed operation of the engine in which the first intake valve is operated in a mode corresponding to the low speed operation and the second intake valve is in a resting or substantially resting condition, and a state meeting at least a part of operational ranges of the engine other than the low s

Abstract: The two-stroke engine includes at least one cylinder, a piston reciprocable within the cylinder and a cylinder head which contains at least one exhaust port which is controlled by a poppet valve and at least two inlet ports which are controlled by respective poppet valves and are connected to respective inlet ducts. The inlet ports are of directed type with the axes of the inlet ducts being convergent in the direction of flow whereby the air flowing through them into the cylinder flows preferentially generally towards the cylinder axis. The axes of the inlet ducts pass substantially through the cylinder axis where the air flows through the inlet ports merged to form a single air flow on or adjacent the cylinder axis.

Abstract: A two-stroke engine includes at least one cylinder, a piston reciprocable within the cylinder and a cylinder head which contains at least one exhaust port and at least two inlet ports which are controlled by respective poppet valves. The cylinder defines a combustion chamber of pent-roof form with which the inlet and exhaust ports communicate. The inlet ports are of directed type whereby, in use, the flow of air through them is generally away from the exhaust valve(s) and thus flows down the wall of the cylinder adjacent the inlet port. The axes of the inlet ducts converge in the direction of flow through them and the axis of each inlet defines angle of at least 20.degree. with that of the other inlet duct when viewed in the direction of the cylinder axis.

Abstract: An intake system having first, second and third intake ports connected to first, second and third air intake passages, respectively and up stream ends of three air intake passages are connected to a common air intake passage. The first air intake passage is set to supply air through the first intake port along an inner peripheral surface of the combustion chamber. The second and third air intake passages are set so that axial center lines thereof may intersect an axial center line of the first air intake passage and an intersecting point of the axial center lines of the third and first air intake passages are up stream of the intersection of the axial center lines of the second and first air intake passages. Thus, swirl of intake air in the combustion chamber from the third intake port is stronger than that generated by the intake air from the second intake port. Then, swirl around an ignition plug arranged almost in the center of the combustion chamber is strengthened.

Abstract: An air-fuel ratio control system in an internal combustion engine, whereby an acceleration condition is detected to obtain an enrichment correction of a fuel injection amount. An occurrence of a mild acceleration is detected by calculating a value of a rate of change in a parameter of an engine load, such as a degree of opening of a throttle value, between adjacent timings, accumulating values of the rate of change of the engine load parameter during a sampling period, and comparing the accumulated value with a predetermined threshold value.

Abstract: A stratified-combustion internal combustion engine according to the present invention comprises at least two intake ports situated on one side of a combustion chamber, guide passages connected individually to the intake ports, a fuel injector disposed in one of the guide passages. Each guide passage has a straight region extending over a predetermined length from its corresponding intake port. Thus, an air-fuel mixture and air, guided by the respective straight regions of the guide passages to be supplied through their corresponding intake ports to the combustion chamber, flow along the axial direction of a cylinder bore, thereby forming barrel swirl flow separated in layers from each other.

Abstract: There is disclosed an internal combustion (V-8) engine having an improved form of cylinder head and intake manifold for augmented combustion air flow and improved fuel mixing wherein the intake chamber immediately upstream of the intake valve is provided with two inlet ducts rather than the usual one inlet duct. The primary inlet duct may be conventional; the secondary inlet duct branches off in a direction more nearly parallel to the central axis of the cylinder and preferably connects to an inlet pipe which draws air through an independent air filter. The secondary inlet duct is provided with its own butterfly valve which can be independently controlled either automatically or manually and may be provided with a fuel injector. Secondary inlet ducts of the system can be attached on the outside to the inlet stacks (for injected engines), to an air breather base (on carburated engines), or to draw filtered air from the atmosphere directly into the system.

Abstract: A cylinder head and valve train mechanism for an internal combustion engine having six valves per cylinder. There are provided four intake valves and two exhaust valves. In some embodiments, the size of the intake valves is varied because they are served by a common port so as to insure equal flow to the cylinder through all valves. In one embodiment, a single insert forms two of the valve seats. Also, two of the four valves are disposed at acute angles to both a plane containing the cylinder bore axis and a perpendicular plane passing through this axis in many embodiments. In these embodiments, the cam lobes that operate the angularly disposed valves have cam surfaces that are inclined relative to the axis of rotation of the camshaft. In some embodiments, all of the intake valves are operated by a single camshaft. In other embodiments, two camshafts operate different pairs of the intake valves. Various bearing arrangements for the camshafts are illustrated and described.

Abstract: A cylinder head structure for a multiple cylinder engine, comprising, at least for each of its cylinders (1) located at either longitudinal end of its cylinder bank: a combustion chamber (13) defined by the cylinder and a piston received therein; an intake passage (18) communicated with an intake manifold (20) at its one end and with said combustion chamber at its other end; and exhaust passage (19) communicated with an exhaust manifold (21) at its one end and with said combustion chamber at its other end; at least one of said intake passage and said exhaust passage being curved toward a longitudinally central part of said cylinder bank as it extends from its other end to its one end. Hence, the size and weight of the intake manifold and/or the exhaust manifold can be reduced.

Abstract: To smoothly introduce intake air or mixture through at least one intake valve and exhaust combustion gas through at least exhaust valve, an intake side conical wall surface is formed in an inner wall of the cylinder head in smooth continuous connection with a conical surface formed at an end of the intake valve seat, and an exhaust side conical wall surface is also formed in the inner wall of the cylinder head in smooth continuous connection with a conical surface formed at an end surface of the exhaust valve seat. It is preferable not to allow liquid fuel introduced through the intake to flow directly toward an ignition plug provided at the center of the cylinder, but to allow the introduced liquid fuel to flow directly toward the exhaust port along a flat surface, recess, groove, guide surface, etc. formed around the ignition plug for prevention of misfiring.

Abstract: An intake valve lift control system for optimizing both rotational movement and inducted flow of a mixture inducted into the chambers of an internal combustion engine. The combustion chamber includes a mask partially surrounding the intake valve seat thereby imparting rotational movement to the inducted mixture. During light load engine operating conditions, maximum valve lift displacement is limited to the height of the mask such that rotational movement of the inducted mixture is maximized during the entire intake stroke of the intake valve. During heavy load engine operating conditions in which optimal flow is desire, maximum valve lift displacement is extended beyond the mask such that flow, rather than rotational movement, is optimized. Commencement of valve lift is also delayed during normal engine operations such that rotational movement of the inducted mixture is further optimized.

Abstract: The present invention relates to a combustion system of an internal combustion engine having a combustion chamber with two inlet openings and at least one outlet opening, an intake manifold for inducing mixture, two intake ports bifurcated from the intake manifold and communicated with the corresponding inlet openings and a swirl control valve disposed in the intake manifold. The combustion system has an improvement wherein a side passage in a spiral shape for guiding the mixture by bypassing the swirl control valve is formed along with the intake manifold and one of the intake ports from an upstream side of the swirl control valve to the inlet opening. The swirl control valve is arranged with a predetermined inclination so as to position an edge of the swirl control valve facing to the side passage to the upstream side of the other edge of the swirl control valve when the swirl control valve is fully closed.

Abstract: An intake and exhaust valve system deployed in an internal combustion engine that improves available charge flow through the engine, provides improved charge turbulence and swirl of charge during each intake stroke for better mixture, provides for multiple independent fuel mixing at the cylinder, allows the use of concentric intake and exhaust valves also providing for balanced charge entry exit symmetry. The intake and exhaust valve system includes using a plurality of three or more concentric valve assemblies per cylinder, each intake valve being mounted within a hollow exhaust valve, the multiple intake and exhaust valves providing optimum flow area entering and exiting the cylinder. Three or more charge passage openings per cylinder strategically disposed enhances the uniform distribution of charge per unit time. Utilization of the present invention greatly increases the fuel efficiency of the engine, reduces emission pollution without sacrificing engine horsepower.

Abstract: A two-stroke engine having an intake valve and an exhaust valve which are arranged on the cylinder head. A masking wall is formed on the inner wall of the cylinder head to mask the valve opening between the valve seat and the peripheral portion of the intake valve, which is located on the exhaust valve side, for the entire time for which the intake valve is open. The valve seat and the masking wall are formed by a built-up layer which is built up on the wall of the cylinder head and machined.

Abstract: In an internal combustion engine with two or more cylinders and two inlet valves per cylinder, in which the intake passages of two adjacent cylinders, which lead towards the inlet valves, are located side by side, symmetrically relative to the symmetry plane of the two cylinders, and in which the cylinder head is made in one piece and has one common inlet flange with an inlet channel, which is flow-connected, past a lug receiving one of the cylinder head studs, with the intake passages formed by guiding surfaces and leading towards the individual inlet valves, the intake passages leading to the inlet valves positioned at a lesser distance in the direction of flow are guided on one side of the lug and the intake passages leading to the inlet valves positioned at a greater distance are guided on the other side of the lug, and the inlet valves of the adjacent cylinders are controlled in such a way that the cylinders are fed with combustion air at different points in time.

Abstract: A direct-injection diesel engine comprising a cylinder block having a cylinder in which a piston is slidably received, a cylinder head connected to an upper surface of the cylinder block, a fuel injector nozzle mounted on the cylinder head to directly inject fuel into a combustion chamber defined between the piston and the cylinder head, and first and second independent intake ports provided in the cylinder head for introducing intake gas into the combustion chamber. An intake controller is mounted in the second intake port for bringing the second intake port into a controlled intake gas flow state in a region of low speed operation of the engine and into a normal state in a region of high speed operation of the engine. Each of the first and second intake ports are formed helically in the same direction to produce swirls in the same direction in intake gases introduced respectively through the intake ports into the combustion chamber.

Abstract: An improved pent roof configured combustion chamber for an internal combustion engine wherein the pent roof has a generally D configuration in top plan view so as to prevent opposing squish flow and to generate swirls within the combustion chamber as the piston approaches top dead center.

Abstract: A two-stroke engine having an intake valve and an exhaust valve which are arranged on the cylinder head. A masking wall is formed on the inner wall of the cylinder head to mask the valve opening between the valve seat and the peripheral portion of the intake valve, which is located on the exhaust valve side, for the entire time for which the intake valve is open. Due to the masking wall, fresh air fed into the cylinder is turned around a central axis perpendicular to the axis of the cylinder. A fuel injector is arranged on the inner wall of the cylinder on the central axis to inject fuel therefrom along the central axis.

Abstract: In a multi-cylinder engine, equipped with at least two induction valves per cylinder, with one of said valves having a narrower induction and crossing stroke, and with another of said at least two valves having a wider induction and crossing stroke, and with a choke valve per each cylinder, the invention provides for a fuel injector to be installed substantially in correspondence of the induction valve having the narrower induction stroke and crossing.

Abstract: An intake system with a simple and compact structure for an internal combustion engine having a plurality of cylinders each cylinder having an intake port, the opening timing of the intake ports being determined so that that of each cylinder overlaps with that of another in which the intake stroke takes place subsequently to that in the former, the intake system comprising intake passges each being connected to the intake port of one of the cylinders, a juction portion connected to the respective intake passages, a resonance intake passage connected to the junction portion at one end thereof, in which the intake pressure resonance effect is to be produced and control valves provided in the respective intake passages, the opening timing of the respective control valves being determined so as to be retarded relative to that of said respective intake ports under at least a low speed and heavy load engine operating condition.

Abstract: An internal combustion engine in which each cylinder has a plurality of inlet ports (17,19) and a plurality of outlet ports (14), each port being openable and closeable by means of a respective valve (12,13,11). The inlet and outlet valves (12,13,11) are disposed with their center lines substantially on opposite sides of a cylinder center plane (16) and angled generally towards said center plane (16). There are three, or possibly more, valves on at least one of said sides, arranged with two outer valves (12) separated by one, or possibly more, inner valve (13). The angle of inclination with respect to said center plane (16) for the outer valves (12) is less than or equal to the angle of inclination for the inner valve (13). The valves are preferably operated directly with a separate camshaft (18,20,15) being provided for each one or more valves inclined at the same angle.

Abstract: An ICE with at least one intake port and intake valve has an air inlet passage that is split by a divider wall into primary and secondary runners, the primary being smaller than the secondary. The secondary contains a flow deactivation valve for shutting off or permitting flow to the inlet port opening. The divider wall extends to a point immediately adjacent the intake valve stem so as to positively divide the passage into the two independent runners. The centerline of the primary passage is oriented so as to produce the desired swirl rate to the air flow, other geometric considerations being defined to accurately control the swirl rate of flow and velocity to provide maximum efficiency of operation; one being that the primary passage cross-sectional area be 40%-50% of the total cross-sectional area of the port opening, another being that the volume between the closed deactivation valve and the intake valve being less than 15% of the cylinder displaced volume, and including other sized ratios.

Abstract: Two embodiments of valve driving arrangements for internal combustion engines that permit a low camshaft positioning without adding to the width of the engine. In each embodiment, three intake valves are slidably supported, two in a common plane and the third in a plane that intersects the first plane along a line that is disposed farther from the valve heads than the rotational axis of the camshaft which operates the valves.

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: 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.