Abstract: In an internal combustion engine with a cylinder (1), the cylinder head (2) has four valves (3, 4) inclined towards each other and arranged to be radially aligned with respect to the combustion chamber, pairs of the valves being operable by a common camshaft (6) by means of conical cams (7). To make it possible to use such a valve control for high rotational speeds, too, bucket type tappets (8) are displaceably mounted between the radially aligned valves (3, 4) and the conical cams (7) in the cylinder head (2).

Abstract: An improved induction system for a V type engine that improves both charging and combustion efficiency. The engine includes an induction system for each cylinder barrel that includes a pair of intake valves and respective intake passages that have a common inlet. One of the intake passages is curved and an auxiliary intake passage extends through the cylinder head and terminates at an auxiliary intake port that is disposed at one side of the main intake port in proximity to the cylinder barrel for generating a swirl to the intake charge. A plenum chamber is positioned in the V of the engine and defines two separate chambers each of which communicates with a respective one of the auxiliary intake passages.

Abstract: An embodiment of an induction system for internal combustion engines that permits maximum power output while at the same time insuring good running at low speeds without loss in mid-range torque. Independent intake passages communicate with each chamber of the engine. A throttle valve arrangement is included that includes a first manually operated throttle valve positioned in a common portion of the intake passages, a second manually operated throttle valve that is positioned in the first intake passage between the first throttle valve and the chamber, and a third throttle valve positioned in the second intake passage between the first throttle valve and the chamber. A linkage system interconnects the first and second throttle valves so that the second throttle valve is opened at a predetermined degree of opening of the first throttle valve. The linkage causes the first and second throttle valves to reach their fully opened position simultaneously.

Abstract: An internal combustion engine in which a stream of air from a duct (46) to a cylinder (2) so as to flow adjacent to the cylinder walls. The duct (46) is arranged to admit the air only while the exhaust valve (42) is open. The air will circulate against the cylinder walls during the exhaust stroke but at least a portion thereof will remain adjacent the cylinder walls during the subsequent compression stroke. The combustible charge is admitted generally centrally of cylinder and remains stratified with respect to the circulating air. The circulating air maintains the combustible mixture relatively concentrated for good ignition, cushions the igniting gases, assists in maintaining the cylinder walls clean and cools the exhaust valve.

Abstract: An intake arrangement for an internal combustion engine, including a plurality of intake ports opening into a combustion chamber, a plurality of intake valves for opening and closing the intake ports, respectively, a main intake passage having a plurality of branch intake passages connected to the intake ports, respectively, a shutter valve for opening and closing the main intake passage, and an auxiliary intake passage branched from the main intake passage and connected to one of the intake ports.

Abstract: Several embodiments of induction systems for internal combustion engines embodying three intake valves per cylinder. Each system divides the induction passage for each cylinder into at least two parts and a flow controlling throttle valve is positioned in one of the parts. In some embodiments, the parts have equal effective flow areas and in others they have unequal flow areas. In further embodiments, there are three intake passages serving the same chamber and throttle valves are positioned in two if them. In some of these embodiments, the throttle valves are operated simultaneously while in others they are operated in staged sequence.

Abstract: Several embodiments of valve actuating mechanisms for internal combustion engines that facilitate the use of more intake and/or exhaust valves than the other type of valve. This is accomplished by embodying lifters or tappets that have a smaller diameter for the valves having the greater number.

Abstract: Disclosed is an engine having a swirl control valve in the intake port. When the engine is operating under a partial load, a lean air-fuel mixture is fed into the engine cylinders, and the swirl control valve is closed in order to create a swirl motion in the combustion chamber. When the throttle valve is fully open, a rich air-fuel mixture is fed into the engine cylinders, and the swirl control valve is closed. In addition, the ignition timing is retarded. After this, when the throttle valve is slightly closed, the swirl control valve is maintained at the open position, and the air-fuel mixture of an approximately stoichiometric air-fuel ratio is fed into the engine cylinders. At the same time, the ignition timing is slightly advanced.

Abstract: An engine having an intake port which comprises a straight port and a helical-shaped port which are separated by a separating wall. A control valve is arranged in the inlet portion of the straight port and opens when the engine is operating under a heavy load. A projection is formed on the side wall of the separating wall, which defines the straight port and is located downstream of the control valve. A bypass passage connected to the helix terminating portion of the helical portion of the helical-shaped port is formed in the separating wall. The projection has an arc-shaped cross-sectional tip face which is directed towards the upstream of the intake port. The inlet opening of the bypass passage is formed on the tip face of the projection.

Abstract: A valve train for an internal combustion engine embodying an improved valve spring arrangement that permits a compact valve placement. The valve springs are disposed so that they are non-circular in planes perpendicular to the axis of the associated valve stem and are disposed with a long axis and a short axis. The long axes of the respective springs extend parallel to each other so as to facilitate the close placement of the valves.

Abstract: An engine with three intake ports and three intake valves for each cylinder. The first intake port is a helical port. The remaining two intake ports have intake control valves, which open when the engine speed and the engine load are large and close when the engine speed and the engine are small. Air thus is introduced alternatively from the first port only or from all the ports. Fuel is injected in the third port between the corresponding intake valve and intake control valve.

Abstract: Stratification of charge in a four stroke internal combustion engine in which a stream of air issues from a duct (46) and is directed tangentially into a cylinder (2) to circulate about the cylinder adjacent to the cylinder walls. The air is admitted to the cylinder only while the exhaust valve (42) is open. The air circulates adjacent to the cylinder walls during the exhaust stroke and at least a portion thereof remains adjacent the cylinder walls during the subsequent induction and compression strokes. The combustible charge is admitted generally centrally of the cylinder and remains stratified with respect to the circulating air which contains the combustible mixture as a relatively concentrated central core whereby reliable ignition is achieved. The method may also be applied to two-stroke engines and to diesel engines.

Abstract: An internal combustion engine which devises the opened direction and position of the gas outlet end of a sub-suction path provided separately from a main suction path so as to inject a gas in the circumferential direction of a combustion chamber during the suction stroke, in which the outlet end of the sub-suction path opens within such a range that, in a plane normal to the axis of the cylinder, the line extending in an opened direction of the sub-suction path is at an angle of .+-.20 to 110 degrees with respect to the line joining the center of the suction port and the axis of the cylinder; the distance between the outlet end of the sub-suction path and the face of a suction valve at its closed position is not more than the internal diameter of the main suction path; or the outlet end of the sub-suction path is positioned within a sphere with its center being a spark point of an ignition plug and with the same diameter as the internal diameter of the cylinder and within a range of .+-.

Abstract: A cylinder head 1 has four valves 2, 4 per cylinder and the desirable arrangement whereby the sparking plug 7 electrodes are in the center of the four valves. The sparking plug 7 is housed in a tube 29 to protect it from the oil in the valve gear region of the head. By appropriate choice of dimensions, it has been found possible to operate the valves 2, 4 via rockers 9, 11 by means of a camshaft 18 located in the vee-space between the valves, while still allowing room to accommodate the sparking plug 7. A desirable compactness is thereby achieved.

Abstract: An engine intake system includes a combustion chamber, a first intake port opening to the combustion chamber, and a second intake port opening to the combustion chamber. A shut-off valve is provided for blocking intake gas flow to the combustion chamber through the second intake port in a first engine operating region wherein engine load is relatively small, and allowing the intake gas to flow to the combustion chamber through the second intake port in a second engine operating region wherein the engine load is relatively large. A first valve actuating mechanism is provided for opening the first intake valve at a first timing, and a second valve actuating mechanism is provided for opening the second intake valve at a second timing.

Abstract: An engine in which the cylinders are each provided with a first intake valve, a second intake valve and an intake passage common to the first and second intake valves. The intake passage is divided into a central passage and two side passages located on each side of the central passage by two side separating walls, which extend from the valve stem guides of the first and second intake valves toward the upstream of the intake passage. The downstream end portion of the central passage is divided into two branch passages. Each of the branch passages is in communication with the corresponding side passage via an opening formed in the corresponding side separating wall. A fuel injector is arranged in the central passage, and a control valve is arranged in the central passage upstream of the fuel injector and opens when the engine is operating under a heavy load.

Abstract: An internal combustion engine provided with a first port of a helical shape and second port of a straight shape opened to the combustion chamber. The first port provides a swirl motion in the cylinder, while the second port is opened to the combustion chamber at a position near the spark electrodes located at the upper portion of the combustion chamber in the center thereof. An intake control valve selectively opens or closes the second intake port in accordance with operating conditions of the engine. A main injector is arranged in the second port downstream of the intake control valve. The injector is so controlled that it opens substantially during the intake stroke when the intake control valve is closed. The injector is controlled to inject at the period substantially not located in the intake stroke.

Abstract: A four cycle internal combustion engine including a secondary intake system. The secondary intake system includes a pumping diaphragm actuated by pressure variation within the engine crankcase. The pumping diaphragm is in turn connected to the intake passage through a secondary intake passage to receive and expel air/fuel mixture toward the intake valving at appropriate intervals. A control valve control communication between the crankcase and the pumping diaphragm to restrict or allow actuation of the pumping diaphragm. An outlet also extends from the system to vent the crankcase at appropriate intervals.

Abstract: An intake system for an automotive engine having cylinders, primary intake ports communicated with the cylinders, and secondary intake ports communicated with the cylinders. Each of the primary and secondary intake ports is communicated with a corresponding cylinder at a common intake valve. A primary intake manifold communicated with the primary intake ports and a secondary intake manifold communicated with the secondary intake ports are provided. A control valve is provided in each branch of the secondary intake manifold for controlling a counter flow of induced mixture. A vacuum operated actuator opens the control valve in dependency on an increase of engine speed and load on the engine.

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: An improved intake system in an internal combustion engine of a high compression ratio capable of producing a swirl of air-fuel mixture so as to increase the combustion speed thereof for improved combustion efficiency and hence fuel economy during light-load operation of the engine, and at the same time of effectively suppressing the generation of a swirl so as to reduce the level of combustion noises to a substantial extent during heavy-load operation of the engine at full-open throttle. The engine has a combustion chamber defined in a recess in the cylinder head above the top of a piston, slidably received in a cylinder bore in the cylinder block, at its top dead-center, with a squish area of a limited clearance formed adjacent the combustion chamber in the cylinder bore between the cylinder head and the piston.

Abstract: An internal combustion engine comprising four valves for each cylinder consisting of a first pair of continuously operable intake and exhaust valves and a second pair of additional, optionally disconnectible intake and exhaust valves, the valve lift curve of the first pair being intended for torque in the partial load range and the second pair for power in the full load range, the engine including two overhead camshafts for actuating the four valves per cylinder, with the valves arranged so that in each case the disconnectible valves of two adjacent cylinders are adjacent to one another and may be actuated by cams on a sleeveshaft which is freely rotatable on the camshaft but may be coupled rotationally rigidly at the correct angle to the camshaft by way of an axially slidable shift collar.

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 method and a system is disclosed for controlling ignition timing in an internal combustion engine having a throttle valve and an intake air control valve independent of said throttle valve. Ignition timing is controlled in synchronism with the on-off operation of the intake air control valve. A change in the ignition timing is delayed by a predetermined period of time corresponding to a delay time in completing the on-off operation of the intake air control valve so that the optimum ignition timing is obtained at the proper time.

Abstract: A suction system for an internal combustion engine having a sub-suction path for generating a swirl of suction gases in a combustion chamber. The sub-suction path is in addition to the main suction path to be opened or closed by a suction valve. More specifically, in a multicylinder internal combustion engine, path portions for constructing the sub-suction path are formed in a cylinder head, a suction manifold and a carburetor such that the sub-suction path is automatically constituted when the carburetor is connected to the cylinder head through the suction manifold, without further connections being necessary.

Abstract: An embodiment of induction system for internal combustion engines that permit maximum power output while at the same time insuring good running at low speeds without loss in mid-range torque. Independent intake passages communicate with each chamber of the engine. A throttle valve arrangement is included that includes a first manually operated throttle valve positioned in a common portion of the intake passages, a second manually operated throttle valve that is positioned in the first intake passage between the first throttle valve and the chamber, and a third throttle valve positioned in the second intake passage between the first throttle valve and the chamber. A linkage system interconnects the first and second throttle valves so that the second throttle valve is opened at a predetermined degree of opening of the first throttle valve. The linkage causes the second throttle valve to be moved to its fully opened positioned before the first throttle valve is fully opened.

Abstract: A method for controlling intake flow of an internal combustion engine having an intake port including a helical passage and a straight passage both extending towards a common port end opening which opens to the combustion chamber of the engine, in such a manner that a minimum proportion of intake flow is directed through the straight passage during idling operation of the engine regardless of the temperature condition of the engine, a maximum proportion of intake flow is directed through the straight passage during loaded operation at any non idling load of the engine when the engine is not warmed up, and a proportion of intake flow increasing according to the level of engine load is directed through the straight passage during loaded operation of the engine when the engine has been warmed up. This method is performed by an intake passage switchover control valve system operated conveniently by utilizing intake vacuum under a proper switchover thereof which itself incorporates the engine load performance.

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: An internal combustion engine having a plurality of cylinders each comprising a first intake valve, a first intake passage connected to the corresponding cylinder via the first intake valve, a second intake valve, and a second intake passage connected to the corresponding cylinder via the second intake valve. A second throttle valve is provided for each second intake passage and opens when the load of the engine is increased beyond a predetermined level. A blind common connecting passage is provided, which has a plurality of branch passages each being open to the corresponding second intake passage located downstream of the corresponding second throttle valve.

Abstract: An improved performance internal combustion engine having a pair of intake passages that supply the charge to a single chamber of the engine. A valving arrangement is provided so that the idle charge is supplied primarily through one of the intake passages and the full load charge is supplied through both passages. An interconnecting passage interconnects the passages with each other downstream of the throttle valves so that at least a portion of even the idle charge will be supplied through both passages to cool the intake valves associated with the passages and to ensure against the collection of deposits. In accordance with a feature of the invention, a pair of spark plugs are positioned in the chamber at its outer periphery on diametrically opposite sides of the cylinder.

Abstract: An intake port structure comprises a cylinder head including combustion chambers and supporting an intake valve and an ignition plug in each of the combustion chambers, the intake valve having a stem slidably supported by the cylinder head, the cylinder head having a joint surface to which an intake manifold is connected. A primary intake passage is defined in the cylinder head and communicates with each of the combustion chambers, the primary intake passage having a primary intake port directed toward the stem and the ignition plug, and an opening at the joint surface. The opening has a central axis extending at an angle smaller than 90.degree. with respect to the joint surface. The primary intake passage is smoothly curved between the primary intake port and the opening. The intake manifold has a plurality of primary manifold branches arranged substantially symmetrically with respect to a central axis of the intake manifold.

Abstract: A dual induction type intake system for an internal combustion engine has a primary intake passageway for light load operation of the engine and a secondary intake passageway for heavy load operation of the engine. The downstream side open end of each intake passageway opens toward the intake port of the cylinder of the engine. The secondary intake passageway is provided with a controllable valve therein. The load on the engine is detected and the controllable valve is opened when the load on the engine is heavier than a predetermined value so that the intake gas is introduced into the combustion chamber through both the primary and secondary intake passageways, while otherwise the controllable valve is closed so that the intake gas is introduced into the combustion chamber only through the primary intake passageway.

Abstract: A downstream end of an intake port of an internal combustion engine opens to a combustion chamber as a parallel combination of a helical passage which extends helically around and towards its downstream end and a straight passage which extends substantially straight towards its downstream end, with an intake passage valve system being incorporated so as to selectively alter the proportions of intake flow through the straight passage and the helical passage; and a fuel injection valve injects fuel to the intake port. From immediately after starting of the engine for a certain time period the amount of fuel injected through the fuel injection nozzle is increased by a ratio dependent on the temperature of the engine.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. The side wall of the helical portion has a slightly inclined portion located near the outlet portion of the bypass passage and expanding towards the separating wall so as to define a narrow passage portion between the inclined portion and the separating wall. A rotary valve is arranged in the bypass passage and is actuated by a vacuum-operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. The separating wall has an upstream end portion centrally located between the opposed side walls of the intake port. A rotary valve is arranged in the bypass passage and is actuated by a vacuum-operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. The upper wall of the bypass passage is higher than that of the inlet passage portion. A rotary valve is arranged in the bypass passage and is actuated by a vacuum-operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: A fuel intake system for a supercharged engine including an engine driven supercharger comprises a primary intake passage having a primary throttle valve for controlling the flow of an air-fuel mixture to be supplied to the engine, an auxiliary intake passage having an auxiliary throttle valve for controlling the flow of at least an air supercharged by the supercharger and adapted to be supplied to the engine, and an electromagnetic clutch for initiating and interrupting the transmission of the drive from the engine to the supercharger. The clutch is in position to establish the drive transmission between the supercharger and the engine only during the high load engine operating condition.

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: Controlled amounts of relatively rich mixture and relatively lean mixture are supplied separately to a combustion chamber of an internal combustion engine. The position of the intake valves, exhaust valve and spark plug are such that the rich mixture tends to remain near the spark plug during the compression stroke of the engine and does not disperse throughout the lean mixture. At the time of ignition enriched mixture near the spark plug ignites readily and the flame propagates into and through the lean mixture which fills the remainder of the combustion chamber. Several constructions are disclosed to achieve the desired mixture ratios for various operating conditions of the engine.

Abstract: An intake system for an automotive engine having cylinders, primary intake ports communicated with the cylinders, secondary intake ports communicated with the cylinders. Each of the primary and secondary intake ports is communicated with a corresponding cylinder at a common intake valve. A primary intake manifold communicated with the primary intake ports and a secondary intake manifold communicated with the secondary intake ports are provided.A first valve is provided in each branch of the secondary intake manifold for preventing a counter flow of inducted mixture. A bypass is provided at a position downstream of the first valve for communicating the primary intake manifold with the adjacent secondary intake manifold, and a second valve is provided to be operated to open the bypass when load on the engine exceeds a predetermined partial load.

Abstract: An engine comprising an intake port which has a helical portion and a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion to the helical portion. A rotary valve is arranged in the bypass passage and actuated by a vacuum operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of an engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. The separating wall extends to near the side wall of the helical portion and defines a narrow passage portion therebetween. The width of the upper wall of the inlet passage portion is gradually reduced towards the narrow passage portion. A rotary valve is arranged in the bypass passage and is actuated by a vacuum-operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. A rotary valve is arranged in the inlet portion of the bypass passage so that the axis of the rotary valve is substantially parallel to the axis of the stem of the intake valve. The rotary valve is actuated by a vacuum-operated diaphragm apparatus and is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. The intake port has a bottom wall having a transverse width which is approximately equal to the diameter of the valve head of the intake valve. The opposed peripheral edges of the bottom wall are located on the extensions of the tanget lines of the outer periphery of the valve head of the intake valve. A rotary valve is arranged in the bypass passage and is actuated by a vacuum-operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: An internal combustion engine equipped with a sub-suction path to produce a swirl of suction in the combustion chamber, characterized in that there are two inlets to the sub-suction path, one of the inlets opening into the atmosphere side after bypassing the throttle valve of the carburetor to the venturi and the other being operable by the throttle valve of the carburetor and opening in the duct of the carburetor so that it can be closed by the throttle valve at idling. In this arrangement of the engine, the fuel consumption can be saved; a misfiring can be prevented; an untimely or delayed injection of fuel from the main fuel nozzle in low to high load operation can be averted; and a stable combustion can be assured in medium load operation in which a particularly heavy EGR takes place.

Abstract: Internal combustion engine with at least one combustion chamber produced within a cylinder head or similar device, it being possible to feed a fuel-and-air mixture into said combustion chamber through two inlet valves arranged in the cylinder head and to discharge from the said combustion chamber exhaust gases through two exhaust valves arranged in the cylinder head, with the invention also relating to a method of producing such a combustion chamber by means of a casting process. The invention is characterized in that the combustion chamber (1) consists of four cavities (4,5,6,7) distributed in quadrants with a circular plane forming part of base plane (8) of cylinder head (2), in that each individual cavity (4-7) has a shape which is in the main rotationally symmetrical and in that the cavities (4-7) overlap one another, whereby arc-shaped transitions are formed between cavities (4-7) in base plane (8).

Abstract: An improved intake system for an internal combustion engine is disclosed which includes a combustion chamber, an intake passage and an exhaust passage opening to the combustion chamber, and an intake valve and an exhaust valve disposed in the intake and exhaust passages for opening and closing thereof. The system is featurized by provision of one or more control passage(s) opening to the intake passage in the vicinity of the intake valve, and a supply chamber of a predetermined volume which is in communication with the control passage(s). The system is particularly effective in improving the intake efficiency in small-sized, four stroke cycle engines.

Abstract: An internal combustion engine, which is equipped with a sub-suction path for generating a swirl of the suction gas in the combustion chamber in addition to a main suction path to be opened or closed by a suction valve. The sub-suction path is equipped at its inlet side paths with two fuel supply device-line and atmosphere-line paths, the former of which is opened into the draft passage of a fuel supply device and between the air metering portion of said fuel supply device and a throttle valve downstream of the air metering portion and the latter of which is vented to the atmosphere while bypassing said air metering portion and said throttle valve. With the aforementioned atmosphere-line path, moreover, there is connected a vacuum-operated valve which is made operable in accordance with the vacuum prevailing downstream of said throttle valve.