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 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 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.

Abstract: A suction system for an internal combustion engine which is equipped with a sub-suction path provided separately from a main suction path for generating a swirl of the gases in a combustion chamber during the suction stroke. The amount of the air to be supplied via the sub-suction path to the combustion chamber is less than 40% preferably from 10 to 40%, more preferably from 20 to 30% of the total amount of the air to be supplied to the combustion chamber. Alternatively the effective area of the sub-suction path at its outlet end is 0.2 to 3.0% of that of the main suction path.

Abstract: Internal combustion engine constituted such that two inlets are provided to a sub-suction path which is provided separately from the main suction path and serves to inject gas such as air or air-fuel mixture at high velocity in the peripheral direction of a combustion chamber at the suction stroke; one of said inlets is located upstream of the throttle valve, the other located in the air path of the carburetor at a position where the throttle valve can be shut in time of idling, wherein the effective opening area of the throttle valve can be enlarged through appropriate number and form of the inlets to be shut by the throttle valve and the downstream side inlet of the two inlets is set to be within the range of an angle, i.e., the downstream side inlet is located within the range of 60.degree.-120.degree.

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: An internal combustion engine having a plurality of main suction paths adapted to respectively communication with a single combustion chamber are so provided that they can be opened or closed by different suction valves and in which a plurality of sub-suction paths provided separately of the main suction paths are pointed directing to the single combustion chamber so that the gases injected therefrom during the suction stroke may be swirled in an identical circumferential direction within said identical combustion chamber.

Abstract: An internal combustion engine is described in which the shape and construction of the gas outlet end portion of a sub-suction path is made operative to inject a gas such as air, an air-fuel mixture or exhaust gas circumferentially into the combustion chamber during the suction stroke. The gas outlet end portion has a reduced diameter and an injection nozzle which has a length greater than its internal diameter. Moreover, the gas outlet end portion is constructed of a pipe member which is rotatably and adjustably fitted into the insertion hole of a cylinder head and which is so shaped that the open direction of the outlet end thereof can be changed when it is rotationally adjusted.