Abstract: A two-cycle engine includes a port timing control device for varying a timing of the opening of an exhaust port by a piston. The port timing control means includes a first valve mounted within an exhaust passage adjacent to an upper end of the exhaust port and having a port timing control surface, a second valve mounted on a cylinder block between a cylinder head and the first valve and having a closure surface, and an urging member acting on the second valve to always urge it against the first valve. The first valve is operable to be angularly moved about an axis generally perpendicular to the axis of a cylinder into and out of an extended position where the control surface is disposed slightly below the upper end of the exhaust port to close a part of the exhaust port. The second valve is movable along a generally straight path into and out of an extended position where the closure surface closes that portion of the exhaust port lying between the upper end of the exhaust port and the first valve.

Abstract: The two-cycle internal combustion engine includes an engine block having a cylindrical wall defining a cylinder having a head end, a piston mounted for reciprocative movement in the cylinder, and a passage in the engine block, such as an exhaust passage, a transfer passage, or a crankcase fuel intake passage, terminating at the cylinder wall in a port, such as an exhaust port, a transfer port or a piston-controlled, crankcase fuel intake port, having upper and lower edges. A valve mounted in the passage for movement relative to the port is operable to selectively vary the effective distance of one of the port edges from the cylinder head end and thereby provide the capability of varying the timing of the port opening and/or closing as required to obtain optimum engine performance at different operating conditions.

Abstract: A cylinder liner comprising a generally cylindrical outer wall, a generally cylindrical inner wall defining a cylinder having a bottom end, and an exhaust port communicating with the cylinder and being defined by an upper wall extending between the inner and outer walls and being curved concavely with respect to the bottom end, a lower wall extending between the inner and outer walls and being curved convexly with respect to the bottom end, and opposite side walls extending between the inner and outer walls and between the upper and lower walls and converging toward the bottom end of the cylinder.

Abstract: A porting system for two-cycle internal combustion engines has two exhaust ports located on diametrically opposed sides of the cylinder. A pair of intake or by-pass ports are symmetrically positioned on each side of the two exhaust ports. The flow of fuel mixture is laminar and has a pattern which is inward and slightly upward from each intake port. As incoming streams collide, the gas flows upwardly and forms two mushrooms. Then, the flow is downwardly along the cylinder axis. The downward flow divides into two streams flowing radially outwardly from the center of the cylinder and out the two exhaust ports. With this flow pattern, there is a minimum of mixing of intake and exhaust gases, and as compared to the prior art, more unburned gas is retained in the cylinder to improve power output and reduce fuel consumption.

Abstract: An exhaust control system for a two-cycle engine wherein the cross-sectional area of an exhaust is controlled in accordance with the rpm. of the engine by opening and closing at least one auxiliary exhaust passage with respect to a main exhaust passage. The main exhaust passage and the auxiliary exhaust passage connected to the cylinder are located parallel to each other circumferentially of the cylinder, and the rotary valve in the form of a shaft disposed parallel to the center line of the cylinder is operative to open and close the auxiliary exhaust passage with respect to the main exhaust passage in accordance with an increase and a decrease in the engine speed.

Abstract: An exhaust control system for a 2-cycle engine having at least one combustion cylinder with a longitudinal axis comprises a main exhaust passage and an exhaust sub-passage communicating with the cylinder through respective main and sub-exhaust ports. The sub-port is located laterally of and in spaced relationship to the main exhaust port and further lies in a common plane arranged perpendicular to the cylinder axis. A control means is included which varies the degree of opening of the exhaust sub-passage in accordance with engine speed whereby timing of the ports is not altered.

Abstract: It is an object of this invention to provide a two-cycle engine which enables the prevention of carbon in the exhaust port, and ensures a minimum reduction in the open area of the exhaust port for a long period of time. This is attained by including a groove or shoulder formed in at a least a portion of the wall of an exhaust passage immediately behind an exhaust port, and extending along the edge of an opening defining the exhaust port to disable carbon to adhere easily to the exhaust port, or prevent any thick layer of carbon from adhering to the exhaust port so that the carbon layer may have only a limited strength and be easily removed.

Abstract: Disclosed herein is a method of fabricating an integrally cast engine block including a plurality of cylinders, exhaust passage portions which respectively extend from the cylinders and which form portions of exhaust gas passages of equal length, and a water jacket cavity including respective water jacket cavity portions in encircling relation to the exhaust passage portions, which method comprises the steps of providing a mold cavity which defines the exterior surface of the block, locating one or more disposable cores in the mold cavity so as to provide for the exhaust passage portions and for the water jacket cavity, filling the mold cavity with molten metal to provide a unitarily cast engine block, permitting soldification of the block with the cores contained therein, and removing the disposable cores from within the engine block to provide the hollow exhaust passage portions and the water jacket cavity.

Abstract: An internal combustion engine cylinder liner adapted to have a piston move reciprocally therewithin, the cylinder liner including an exhaust port, an exhaust port bridge extending across the exhaust port, and a relief hole in the cylinder liner positioned at one end of the exhaust port bridge for allowing the exhaust port bridge to expand in a direction other than toward the path of piston movement.

Abstract: An improved two cycle engine is disclosed which includes a subchamber which is in communication with the exhaust port with a cylindrical valve rotatably disposed therebetween. A reed valve unit is turnably supported in the inlet port to open and close the latter. The cylindrical valve is operatively connected to the reed valve unit by way of a linkage mechanism. Either of the cylindrical valve and the reed valve unit is actuated by a servomotor and the other one is actuated by the linkage mechanism. The servomotor is controlled with the aid of a control circuit so as to allow the engine to be operated at a predetermined number of revolutions.

Abstract: A two-cylinder two-stroke internal combustion engine is provided with insed cylinder liners carrying separate thin-walled cooling jackets. In the area of the intake and exhaust ports the walls of the liners are thickened in order to improve the directing of the inflowing charge and to facilitate a leak-proof attachment of the cooling jackets.The areas of the two cylinder liners facing each other are not thickened nor do they have any ports; they are only provided with a collar continuing the upper edge of the thickened portion and serving for the leak-proof attachment of the cooling jacket, such that the space between the cylinders lying below this collar may be utilized for the exchange of fresh charge between the two longitudinal sides of the engine, without the need for an increase of the distance between the cylinders.

Abstract: The two-cycle internal combustion engine includes an engine block having a cylindrical wall defining a cylinder having a head end, a piston mounted for reciprocative movement in the cylinder, and a passage in the engine block, such as an exhaust passage, a transfer passage, or a crankcase fuel intake passage, terminating at the cylinder wall in a port, such as an exhaust port, a transfer port or a piston-controlled, crankcase fuel intake port, having upper and lower edges. A valve mounted in the passage for movement relative to the port is operable to selectively vary the effective distance of one of the port edges from the cylinder head end and thereby provide the capability of varying the timing of the port opening and/or closing as required to obtain optimum engine performance at different operating conditions.

Abstract: The invention relates to a method and to a port-controlled two-stroke internal combustion engine in which the cross-sections of the intake and outlet are so constructed in the direction of the longitudinal axis of the cylinder that in the case of an upward or downward movement of the piston, the noise-generating intake and outlet pressure gradients and amplitudes are reduced by the gradual opening of the particular intake and outlet, the piston lower edge and intakes having special constructions.

Abstract: In a two-stroke cycle internal combustion engine, cylinder structure has an inside peripheral surface which defines a cylinder bore and is formed with an exhaust port, which has an axial extent along the axis of said cylinder bore and communicates with said exhaust system. A piston is axially reciprocable in said cylinder bore and adapted to open and close said port. A restricting member is mounted in said cylinder structure adjacent to said port and adjustable between a full-flow position, in which said restricting member exposes said exhaust port throughout its axial extent, and a restricting position, in which said restricting member restricts the axial extent of said exhaust port. A positioning drive is operatively connected to said restricting member and operable to adjust said restricting member between said full-flow and restricting positions. The positioning drive is adapted to be controlled in dependence on the exhaust gas pressure in said exhaust gas system.

Abstract: A two stroke engine having an exhaust port formed in the cylinder wall. At the upper portion of the exhaust port, there is provided a rotary type exhaust timing control valve which is adapted to be rotatably actuated to control the exhaust timing in accordance with the engine speed. The control valve is interconnected with the engine starting mechanism so that the control valve is forcedly driven by the starting mechanism to thereby eliminate valve seizure.

Abstract: In an internal-combustion engine comprising at least one cylinder having a port and a piston which is reciprocable to open and close said port, the effective axial extent of said port is adapted to be reduced by a restricting member, which is movably mounted adjacent to a flow passage which adjoins said port. The restricting member has a restricting edge and is movable to a restricting position in which said restricting edge is substantially flush with the peripheral surface of the cylinder bore. The restricting member defines the exhaust passage on one side thereof adjacent to the exhaust port. In order to improve the cooling of the cylinder and the exhaust gas flow, the restricting member constitutes a hinged member, which is pivoted on an axis at that end which is opposite to the restricting edge.

Abstract: A two stroke engine having an exhaust port formed in the cylinder wall. At the upper portion of the exhaust port, there is provided a rotary type exhaust timing control valve which is adapted to be actuated by an electric servomotor to control the exhaust timing in accordance with the engine speed. A control circuit is provided for controlling a power supply to the servomotor in accordance with the engine speed and the position of the valve. A timer switch is provided for providing a power supply to the control circuit for a certain time after the engine ignition switch is turned off so that the valve is moved to the retracted position after the engine is stopped. As the valve is thus moved to the retracted position, carbon deposits on the valve is scraped off by a scraping edge formed in the cylinder.

Abstract: A two stroke engine having an exhaust port formed in the cylinder wall. At the upper portion of the exhaust port, there is provided a rotary type exhaust timing control valve which is adapted to be actuated by a centrifugal governor device to control the exhaust timing in accordance with the engine speed. The centrifugal governor device has a governor shaft which extends coaxially with the engine crankshaft and directly connected at one end with the adjacent end of the crankshaft. At the other end, the crankshaft is provided with a magneto device so that the magneto does not have any magnetic influence on the centrifugal governor device.

Abstract: An exhaust timing control device for a two-cycle internal combustion engine, in which a valve member functioning as the upper edge of an exhaust port that opens into the inner circumference of a cylinder is disposed in the upper wall of an exhaust passage from said exhaust port. A valve hole having an elongated cross-section is opened in the wall of the exhaust passage in the vicinity of the exhaust port, and is formed at an inclination with respect to the axis of said cylinder. The valve member is arranged slidably in said valve hole so that it can be retracted into said valve hole until the leading end portion thereof becomes substantially coextensive with the inner wall surface of said exhaust passage.

Abstract: The two-cycle internal combustion engine includes an engine block having a cylindrical wall defining a cylinder having a head end, a piston mounted for reciprocative movement in the cylinder, and a passage in the engine block, such as an exhaust passage, a transfer passage, or a crankcase fuel intake passage, terminating at the cylinder wall in a port, such as an exhaust port, a transfer port or a piston-controlled, crankcase fuel intake port, having upper and lower edges. A valve mounted in the passage for movement relative to the port is operable to selectively vary the effective distance of one of the port edges from the cylinder head end and thereby provide the capability of varying the timing of the port opening and/or closing as required to obtain optimum engine performance at different operating conditions.

Abstract: In a two cycle internal combustion engine having a cylinder, a piston, and an exhaust port, the improvement comprising tapering the edge of the exhaust port farthest into the cylinder where it intersects the cylinder wall as an isosceles triangle.

Abstract: A water-cooled two stroke engine including a cylinder formed with an exhaust port which is adapted to be cyclically closed by a piston reciprocating in the cylinder. The exhaust port is provided at the upper portion with a port timing control valve which is operated to control the port timing in accordance with the engine speed by a piston-cylinder type actuator. The actuator is adaped to be operated by the engine cooling water pressure and has an operating pressure chamber at one side of the piston and a compensating pressure chamber at the other side. The cooling water supply passage has a flow restriction and the pressure upstream of the restriction is introduced into the operating pressure chamber and that downstream of the restriction into the compensating pressure chamber.

Abstract: Two stroke engine having variable exhaust timing, which includes an exhaust timing control member disposed in the exhaust passage in the vicinity of the exhaust port. The control member is of an arcuately curved contour having diameter gradually decreasing from one end toward the other end so that it can readily be assembled in the cylinder simply by inserting from one side of the cylinder. The control member has a longitudinal axis which is inclined with respect to a line perpendicular to a line passing through the center axis of the cylinder and the center of the exhaust port so that the smaller diameter end is closer to the center axis of the cylinder than the large diameter end for making it possible to locate the arcuately curved contour of the control member substantially along the cylinder wall.

Abstract: This invention comprehends a two-cycle internal combustion engine using compression relief to provide a dual compression ratio. Compression relief ports above the exhaust ports of two cylinders firing 180 degrees out of phase connected by a relief passage. The passage is vented at its midpoint. At higher engine speeds exhaust flow, from the cylinder in its power stroke, through the relief passage, blocks the flow from the cylinder in its compression stroke.

Abstract: Two-stroke engine having variable exhaust timing, which includes an exhaust timing control member disposed in the exhaust passage in the vicinity of the exhaust port. The member is of an elongated configuration having a diameter gradually decreasing from the opposite ends to the intermediate portion to provide an external contour of an arcuate sectional configuration. The member is divided into two parts at the intermediate portion in order to facilitate to assemble it in the engine.

Abstract: In a two-stroke, water-cooled internal combustion engine the improvement is disclosed which permits to have a removable cylinder liner type of engine in spite of the intricate constructional arrangement of such engines having transfer ports and exhaust ports. The improvement consists in that the transfer and exhaust ports are formed through the liners and flanged fittings are provided between the liner transfer ports and the transfer ducts so as to ensure complete tightness. Differential-firmness gaskets are provided where appropriate and the engine is then assembled by stay bolts as usual. The construction suggested by the invention not only solves the tightness problem satisfactorily, but minimizes the stresses on the liners, especially the bending stresses.

Abstract: Two cycle internal combustion engines including a cylinder which is provided with one or more exhaust ports adapted to be closed by piston reciprocating in the cylinder. A valve member is provided in co-operation with the upper portion or upper one of the exhaust ports. Said valve member may be interconnected with the engine throttle valve in such a manner that it is closed under lower speed operation and opened under high speed operation of the engine so as to obtain optimum exhaust valve timing throughout the engine operating speed range.

Abstract: An internal combustion type pile driver which has a cylinder, a ram adapted to slide within this cylinder, an anvil fitted into the bottom end of the cylinder and an air intake/exhaust port fixedly provided on said cylinder, is improved so that the height of rise of the ram may be adjustable. The improvement exists in providing a choke opening communicating the interior of the cylinder with the atmosphere for the purpose of adjusting a combustion gas pressure in a cylinder wall between the air intake/exhaust port and a combustion chamber, and either a choke plug or a blind plug is adapted to be fitted in to this choke opening.