Abstract: The invention refers to a cylinder (1) for a two-stroke internal combustion engine intended for a handheld working tool, preferably a chain saw, and the exhaust duct (2) and transfer ducts (3, 4) of the cylinder are symmetrically arranged around a mutual symmetry plane (5) which follows the centre line (6) of the cylinder, and at the mouth (7) of the exhaust duct (2) outside the cylinder, a mounting plane (8) with mounting holes (9) for a directly mounted muffler, is arranged.According to the invention, at least one inlet port (11) is located in the cylinder wall (12) and/or in an adjacent crankcase half (10), and the cylinder's in let duct (13) up to the inlet port (11) is so arranged that it forms a fixed and heat-conducting part of the cylinder, and has a length longer than 0.8 times the diameter (14) of the cylinder, preferably longer than 10 times the diameter.

Abstract: A stratified scavenging two-cycle engine, having excellent scavenging performance and a simple structure which can be manufactured at low cost, includes a cast cylinder block (2, 2a) containing a cylinder chamber (9) and two scavenging ports (14, 14, 14a, 14a), which are provided in opposite portions of the interior wall surface of the cylinder chamber (9). Each scavenging port (14, 14a) and the crank chamber (7) are connected via a scavenging flow passage (20) which includes a generally horizontally extending scavenging flow passage segment (22, 22a) and a generally vertically extending scavenging flow passage segment (21). Two recesses (23, 23, 23a, 23a) are provided in the outer surface of the cylinder block (2, 2a) with each recess being an outwardly directed extension of a respective horizontally extending scavenging flow passage segment. An air supply flow passage member (30, 30a) is attached to the cylinder block to cover a respective recess.

Abstract: A loop scavenge two-cycle internal combustion engine that includes a partial wall partition disposed between a scavenging path and a cylinder bore, with a cooling port formed in the partial wall partition for enabling fresh gas in the scavenging path to contact directly with a peripheral wall of a piston in the cylinder. The fresh gas in the scavenging path directly contacts and efficiently cools the peripheral surface of the piston to prevent heat rise and distortion within the engine. The partial wall partition and cooling port maximize both cooling efficiently and cylinder strength and durability.

Abstract: A two-stroke internal combustion engine having a crankcase provided with a crank chamber, a suction port which opens to the crank chamber, a scavenging passage opening into the crank chamber, and a crankshaft is provided with a flow control surface formed on an inner peripheral wall portion of the crank chamber which is capable of retarding the flow rate of unatomized raw fuel and which extends from the vicinity of the suction port to the vicinity of the scavenging passage. The flow control surface is comprised of a large number of intersecting unit ribs.

Abstract: A stratified scavenging two-cycle engine, which enables a reduction in size and an improvement in productivity, includes a carburetor (6), which is provided between an air cleaner (7) and a suction fitting (4), wherein a mixture flow passage (6B) and an air flow passage (6A) are formed in the carburetor at least generally in parallel with each other, an air control valve (6a) is disposed in the air flow passage in the carburetor, and a mixture control valve (6b) is disposed in the mixture flow passage in the carburetor so that the carburetor and the valves (6a and 6b) constitute a single unit.

Abstract: A crankcase scavenged two-stroke engine includes a piston reciprocably mounted in a cylinder. The cylinder wall has an exhaust port and a rear transfer port opposed thereto formed in it. The rear transfer port communicates with the interior of the crankcase via a rear transfer passage and is arranged to open before the exhaust port closes, whereby, in use, the cylinder is scavenged. An inlet duct is arranged to supply combustion air to the crankcase and a throttling valve is arranged to throttle the flow of air through the inlet duct. A carburettor is arranged to supply fuel into the inlet duct. The interior of the crankcase is divided into at least two separate crankcase volumes, a rich volume (V1,V2) and a lean volume (V3). Each crankcase volume communicates with the cylinder via a respective hole in the crankcase wall. The cylinder wall also has at least one lateral transfer port formed in it at a position between the rear transfer port and the exhaust port.

Abstract: To provide a compact two-cylinder engine in which adjacent cylinders are located close to each other. In the two-cycle engine of the present invention, the scavenging passages of scavenging ports adjacent to the exhaust ports are flat or elongate in their cross section and extend to the sides of the exhaust ports. This structure allows the cross-sectional area of the scavenging passages to be sufficient, but allows the width of the cylinder section between adjacent cylinders to be decreased. Furthermore, in the two-cycle engine of the present invention, the exhaust passages of the cylinders are arranged in the direction substantially orthogonal with the direction of alignment of the cylinders, and the exhaust control valves are positioned near the exhaust ports in order to control an opening amount of the exhaust ports.

Abstract: Cylinder (1) for a two-stroke combustion engine intended for a handheld working tool, preferrably a chain saw. The exhaust port's (3) mouth (17) inside the cylinder as well as the cylinder's transfer ports (5, 6, 7, 8) are arranged symmetrically around a common symmetry plane (9) which follows the cylinder's symmetry axis (10). At the exhaust port's (3) mouth (11) on the outside of the cylinder a fastening plane (12) with fastening holes (13) is embodied for a directly mounted muffler, and the fastening plane (12) is essentially perpendicular to the symmetry plane (9), and the exhaust port is angled sideways in relation to the symmetry plane (9) and its mouth (11) is shifted sideways in relation to the symmetry plane (9).

Abstract: The invention is directed to a two-stroke engine for a portable handheld work apparatus such as a motor-driven chain saw. The engine includes a cylinder housing and a crankshaft journalled in shaft bearings. The cylinder housing is closed by a crankcase cover. Half shells are formed in the cylinder housing and the crankcase cover to accommodate the shaft bearings. Overflow channels are formed in the wall of the cylinder and lead from the crankcase to the combustion chamber. The overflow channels are open at their ends facing toward the crankcase cover and interrupt the support surface of the half shells formed in the cylinder housing. An adequate support of a small crankshaft bearing is ensured for an arrangement of several overflow channels. This is achieved in that the half shells are configured with a significantly larger diameter than the outer diameter of the shaft bearing and a support shell is seated in the free space between the half shell and the shaft bearing.

Abstract: A two-cycle internal combustion engine of the fuel injection type, which comprises a cylinder block provided with a combustion chamber and a scavenging passage; a scavenging passage cover constituting a portion of a wall of the scavenging passage; and a fuel injection nozzle mounted on and penetrating through the scavenging passage cover, a distal end portion of the fuel injection nozzle being directed into the combustion chamber so as to inject the fuel directly into the combustion chamber.

Abstract: In a two-stroke internal combustion engine, output power is increased and total hydrocarbon (THC) exhaust is decreased as a result of small structural changes. An exhaust port and scavenging ports are configured and disposed such that they are open in a reduced period of the combustion cycle.

Abstract: A two-stroke engine for driving a crankshaft includes a cylinder defining a longitudinal elevation axis and having a top wall and a cylindrical side wall terminating in the top wall. A piston is mounted in the cylinder so as to be movable along the side wall for driving a crankshaft. The cylinder and the piston conjointly define a combustion chamber wherein combustion gases are generated during operation of the engine and the side wall of the cylinder has an exhaust window which opens into the combustion chamber for conducting away the combustion gases. The exhaust window defines a longitudinal center axis passing approximately through the elevation axis and the side wall of the cylinder has a surface portion lying opposite the exhaust window. A plurality of main channels and a plurality of support channels open into the combustion chamber for conducting fuel mixture into the combustion chamber.

Abstract: An internal combustion engine is provided with a top hat piston disposed in a cylinder having first and second portions of different diameters. The piston, with first and second portions of different diameters, is disposed within the cylinder and defines a compression chamber between a cylinder step and a piston step created by the different diameters. The compression chamber is connected in fluid communication with a fuel supply, such as a carburetor or fuel injector, which provides a fuel/air mixture into the compression chamber during the downstroke of the piston. When the piston is moving upward, it compresses the fuel/air mixture within the compression chamber until a second end of a transfer passage is moved into fluid communication with a transfer port formed in the wall of the first portion of the cylinder. This occurs after the exhaust port is closed by the piston and therefore significantly diminishes the chance for unburned fuel to pass directly out the exhaust port from the combustion chamber.

Abstract: A four-cycle internal combustion engine wherein the piston connecting rod crankshaft and crankcase chamber are formed so that the crankcase chamber acts as compressor. An induction system supplies atmospheric air to the crankcase chamber and a pressure conduit supplies air from the crankcase chamber to the engine intake valve. A plenum chamber is disposed within this pressure conduit and pressure control is possible by bypassing air form the plenum chamber to the atmospheric air inlet. A throttle valve is positioned downstream of the plenum chamber so as to improve engine braking and charge forming systems are disclosed that permit a compact assembly and good response under all engine running conditions.

Abstract: A number of embodiments of two-cycle engines employing Schnurle-type scavenging. In addition and in some embodiments, a ramble port is also incorporated so as to introduce a tumble charge into the combustion chamber and reduce the likelihood of fresh charge from exiting from the exhaust port. This tumble charge may be utilized to achieve stratification, and the fuel charge may be delivered to the combustion chamber through the tumble port or in proximity to it. Various arrangements are shown for controlling the amount of scavenge flow to improve stratification and fuel vaporization.

Abstract: A two-stroke internal combustion engine in a working machine such as a chain saw has been prone to stalling when the stance of the machine was changed from slanting down to slanting up. Such stalling is minimized when lower longitudinal scavenging passage in the cylinder block of the engine have smaller cross section as compared with upper scavenging passage, and when the crank chamber of the engine includes a flow restricting portion for impeding the flow of liquid fuel into the lower scavenging passage when the stance is changed. The engine has a cylinder block (12), a crankcase (20), scavenging passages (27, 27), and a flow restricting portion (40) on an inner peripheral surface (22a) of the crank chamber (22).

Abstract: A two-cycle internal combustion engine is provided which is capable of preventing the blow-by phenomenon, thereby improving both fuel economy and exhaust purifying performance, and superior in the response of fuel injection volume. In a two-cycle internal combustion engine wherein a chamber is disposed in scavenging passages which provide communication between a crank chamber and a combustion chamber, sealable control valves are disposed in an inlet and an outlet, respectively, of the chamber. A fuel feeding system is provided for the supply of fuel into the chamber. The chamber is brought into communication with one scavenging passage out of a plurality of parallel scavenging passages. The control valve, disposed in the chamber outlet which is on the combustion chamber side and on a scavenging downstream side, is positioned at the bottom part of the scavenging passage communicating with the chamber with respect to the control valve disposed in the chamber inlet which is on the crank chamber side.

Abstract: Air/fuel mixture supply device for a two-stroke internal-combustion engine, of the type with scavenging by compressed air in the casing, comprising at least one cylinder, a piston capable of reciprocating motion in the cylinder, and a scavenging-air compression casing, the cylinder comprising at least one exhaust port, at least one transfer port and a port for introduction of an air/fuel mixture.A rotary closure member (19) driven in synchronism with the rotation of the engine is associated with the port (16) for introduction of the air/fuel mixture into the combustion chamber, this closure member being placed in an air reservoir (14) fed with air under a pressure greater than the pressure in the combustion chamber (10) after opening of the exhaust port (11).

Abstract: A multi-cylinder reciprocating piston internal combustion engine, preferably operating on the two-stroke cycle, having a cylinder block 8 incorporating a bank of cylinders 10 each communicating with a crankcase 15. Each cylinder having inlet ports 20,21,22,29,30 located on each of the two opposite sides of the bank of cylinders 10, and a conduit 17 communicating at least one port on one side of the bank with at least one port on the opposite side of the bank. That conduit 17 extends through a crankshaft bearing support portion 14a of the cylinder block 8 located within said crankcase 15 below the level of the cylinders 10. There is preferably one bearing support portion 14a within the crankcase 15 and below the junction between each two adjacent cylinders 10, with a respective conduit 17 extending through said bearing support portion 14a.

Abstract: A two-stroke engine of crankcase scavenged type includes a piston reciprocably mounted in a cylinder, an exhaust port, an inlet port arranged to supply combustion air to the crankcase and a transfer port comprising two or more transfer passages extending between the crankcase and the cylinder. The transfer port is arranged to open before the exhaust port closes whereby, in use, the cylinder is scavenged. Fuel metering means communicates with at least one but not all of the transfer passages and is arranged to supply fuel into the said transfer passage at a rate which is directly determined by the mass flow rate of air through the inlet port. The fuel metering means includes a metering valve connected to actuating means, which is arranged to modulate the valve in response to the mass flow rate of air through the inlet port and fuel supply means arranged to supply pressurised fuel continuously to the metering valve.

Abstract: A variable volume transfer duct for maintaining an optimum volume of buffer gas in the transfer duct of a two-stroke engine during operation in order to minimize short circuit loss of fresh charge at all load levels during engine operation. The variable volume transfer duct that has two pieces, a top and a bottom duct wherein the bottom duct is aligned with and slidably disposed within the upper duct. Control means are provided for raising and lowering of the bottom duct to vary the transfer duct volume accordingly. A control means controls recirculates exhaust gas, or the secondary air, as buffer gas that fills the top of the transfer passage and regulates the buffer gas according to engine load conditions such that it provides a larger amount at higher loads and a lesser quantity at lighter loads.

Abstract: Embodiments of the scavenge passages and the scavenge ports for a two cycle crankcase compression engine wherein the scavenge ports have their side edges tapered outwardly to facilitate the flow into the cylinder block.

Abstract: The invention is directed to a two-stroke internal combustion engine for handheld portable tools such as a motor-driven chain saw with the engine having a piston guided in a cylinder. The base of the piston is rotationally symmetrical and delimits a combustion chamber. An injection valve is mounted in the cylinder wall opposite an exhaust opening for exhaust gases. The injection valve injects fuel toward the piston base at an angle of less than 90.degree.. At least one overflow opening is arranged in the cylinder wall between the exhaust opening and the injection valve. Combustion air flows in through the overflow opening with the downward movement of the piston. The injection jet is directed opposite to the flow direction of the entering combustion air. The injection jet is directed for the most part to the half of the piston base which is disposed away from the exhaust opening and the injection opening is the last opening to be closed by the piston travelling toward top dead center.

Abstract: An improved air intake passage arrangement for use on an internal combustion engine is disclosed wherein intake passages are integrated with the crankcase such that an outer wall of the crankcase defines an inner wall of the intake passages. This construction minimizes the size of the engine and promotes heating of the air flowing within the intake passages. In addition, depending upon the location of the fuel supply lines, the air intake structure of the present invention can enhance the vaporization of the fuel sprayed therein.

Abstract: A fuel injection system for engines that employs a fuel injector that sprays into a chamber to which compressed air is delivered and which chamber communicates with the combustion chamber through a port that is opened and closed by the reciprocation of the piston in a reciprocating engine. The source of compressed air may either be an air compressor or a crankcase chamber of the engine and the air compressor and/or crankcase chamber may also provide scavenging air for the engine. A variety of port arrangements are disclosed which include either single ports or a plurality of ports either circumferentially or axially spaced from each other and disposed between either the scavenge ports and exhaust ports or around a scavenge port or an exhaust port. Various arrangements are disclosed for improving the vaporization of the fuel in the chamber in which it is injected.

Abstract: A number of embodiments of scavenging port configurations for two-cycle internal combustion engines wherein the a scavenge port is formed adjacent the exhaust port and is masked by a cylinder liner so as to avoid the escape of scavenging gases to the exhaust port, particularly at the end of the scavenging cycle.

Abstract: An improved scavenging system for a two cycle internal combustion engine wherein the cylinder block of the engine is provided with an internal plenum chamber that surrounds the lower portion of the cylinders and which supplies the scavenge ports of the engine. In this way, it will be ensured that the proper air flow can issue from each scavenge port.

Abstract: Two embodiments of two cycle, crankcase compression engines wherein exhaust emissions are controlled by controlling the amount of scavenging air flow at low and mid ranges. The scavenging air flow is controlled by balance passages that interconnect at least two crankcase chambers of the engine and in which a control valve is provided. In one embodiment, the balance passage is positioned above the crankcase chambers and communicates with them through downwardly extending passages so as to preclude the likelihood of condensation of fuel or lubricant in the balance passages and to return any fuel or lubricant to the crankcase chambers.

Abstract: A fuel injection system for engines that employs a fuel injector that sprays into a chamber to which compressed air is delivered and which chamber communicates with the combustion chamber through a port that is opened and closed by the reciprocation of the piston if applied to a reciprocating engine. The source of compressed air may either be an air compressor or a crankcase chamber of the engine and the air compressor and/or crankcase chamber may also provide scavenging air for the engine. A variety of port arrangements are disclosed which include either single ports or a plurality of ports either circumferentially or axially spaced from each other and disposed between either the scavenge ports and exhaust ports or around a scavenge port or an exhaust port.

Abstract: Several embodiments of fuel injection systems for two cycle internal combustion engines wherein fuel is injected into a conduit for delivery into the combustion chamber through a port in the cylinder liner. A nozzle insert is positioned in the conduit and has a restricted opening that forms the discharge through which fuel and gas under pressure are supplied to the combustion chamber for facilitating servicing and replacement.

Abstract: A motor block for a multiple cylinder internal combustion motor, particularly an outboard motor, has a cooling passage that is integrally cast as a part of the motor block casting that extends from a water jacket in the cylinder head area to a water jacket space that is provided between the banks of cylinders in the V-block motor.

Abstract: A two-stroke cycle reciprocating internal combustion engine for spark ignition and crankcase scavenging comprises a fuel injection nozzle and an arbitrarily operable throttle valve, which is provided in an air intake passage in upstream of leaf spring dampers, which are biased in a cloging sense.

Abstract: A plurality of cylinders have a predetermined firing order. The crank case of the engine is divided by partitions so that each piston has its own crankchamber. Air is induced into the crank chambers via reed valves and subject to compression as the respective piston descends. Transfer ports are provided which open when the pistons have descended by a predetermined amount from TDC and which inject scavenging air from the crankchamber of the previous cylinder on the firing order, into the combustion chamber of the instant cylinder.

Abstract: A two-stroke engine with controlled pneumatic injection is disclosed, wherein at least one connecting duct joins the combustion chamber of a first cylinder to the crankcase-pump of a second cylinder. The means for controlling the injection of carburetted air into the chamber of the first cylinder comprise at least one flange fixed rigidly to the shaft of the crankcase of the engine inside the crankcase-pump of the second cylinder. The flange comprises a recess on its peripheral portion so as to be able to isolate the crankcase-pump from or place it in communication with the inner volume of the combustion chamber at given times of the engine cycle.

Abstract: A two cycle engine with pneumatic injection, with the engine including a cylinder, a crankcase communicating with one end of the cylinder, and at least one transfer passageway joining the crankcase to the cylinder. A fuel injector is supplied with compressed air by a container connected to the crankcase and a flow restriction arrangement for restricting the flow of gases is disposed in the transfer passageway. The opening and closing of the flow restriction arrangement is controlled and regulated as a function of at least one engine operating parameter, with the overall result being an improvement in a quality of the fuel injection into the two cycle engines.

Abstract: A two cycle, crankcase compression internal combustion engine which has one or more individually sealed crank chambers defined by one or more crank webs and a transfer passage associated with each chamber formed within the crankshaft body and cylinder block to provide increased flow area for the fuel/air mixture between the induction system and each cylinder. An inner wall forming portion of the crankcase body is expanded outwardly around crank webs and has an inwardly extending member associated with each crank web. A groove is formed in each inwardly extending member and cooperates with each of the outwardly expanding areas to define each of the transfer passages.

Abstract: A cylinder block includes a cylinder with a piston therein and a main crankcase. A combustion space is disposed above the piston and a compression space is disposed below the piston. An exterior passage including a reservoir transfers compressed air from the compression space to the combustion space. A first valve permits one-way flow of ambient air into the compression space, and a second valve permits one-way flow from the compression space into the passage so that the compression process is independent of the combustion process. In one embodiment, the exterior passage includes a first passage for air and a second passage for fuel-air mixture for selective communication with the combustion chamber. In another embodiment, an inner crankcase is disposed within and spaced from the main crankcase and incorporates the first and second valves.

Abstract: A device (4, 5) for introducing, under pressure, a fuel-air mixture into a first cylinder of an internal combustion engine, with the engine comprising at least one other cylinder having a pump crankcase. A connecting passageway (9) is provided between the pump crankcase (12) and the upper part of first cylinder (1), with the passageway being supplied with fuel. A communication between the passageway and the combustion chamber of the first cylinder is blocked, and a non-zero angular offset exists between the cycles of the cylinders. The device (4, 5) controls the start of injection by interrupting, in an intermittent and predetermined fashion, the communication between the passageway (9) and the pump crankcase.

Abstract: The invention relates to a method and apparatus for arranging a post-charging two-stroke engine. The apparatus includes a post-charging system (16) including an air admission duct (22) to the cylinder (14). The duct communicates intermittently either with the source of scavenging air (A) or alternatively with a chamber (30) for storing gases under pressure. Advantageously, the chamber (30) is inside the piston (12), whereas the air admission duct (22) is formed by at least one curved duct going round the cylinder (14) and having sufficient volume to constitute a reserve of charging air for use in post-charging. The invention improves engine operation.

Abstract: A method and device for introducing a carburetted mixture into a first cylinder of an internal combustion engine under pressure, this engine comprising at least one other cylinder with a pump crankcase, further comprising a connecting duct between the crankcase and the first cylinder, with an angular non zero shift between the cycle of each of the cylinders, and at least one of the gas transfer ports of said other cylinder is positioned so that a back-flow occurs therein during a part of the cycle.

Abstract: To improve control of the scavenging in accordance with the load and speed conditions in a two-stroke internal combustion engine with scavenge passages which open into the interior of the cylinder and an outlet passage and with scavenge ports and an outlet port governed by the piston of said internal-combustion engine, the present invention provides that communication with said scavenge passages is governed by an electromagnetically unlocking pressure-controlled valve, which is positioned in a passageway section and actuation of which within the opening periods of the scavenge ports, blocks the flow of the scavenging agent to the individual scavenge ports to the effect that the period of scavenging is timed relative to the load and speed conditions under which the internal-combustion engine is working.

Abstract: A fuel injection and gasifying system for an internal combustion engine is disclosed. The combustion system includes a piston assembly with a piston furnished with a gasifying chamber, a cylinder which contains the combustion apparatus, a crank assembly with a crankcase, an injection apparatus, and a control apparatus. The crank assembly manipulates the piston assembly between a first position and a second position. The injection apparatus delivers a fuel mixture to the combustion system, and is positioned such that, when the piston assembly is in the first position, the injection apparatus opens into the gasifying chamber, and when the piston assembly is in the second position, the injection apparatus opens into the crankcase. The control apparatus controls the operation of injection apparatus. When the temperature of the gasifying chamber is below the vaporizing temperature of the fuel the fuel is injected into the crankcase.

Abstract: A unique method of manufacturing a liquid cooled cylinder block by means of a die-casting process is disclosed. The cylinder block (12) has a bore (15) with a plurality of apertures. There is an intake passage (24) through the cylinder block (12) which terminates in an intake port (25) in the bore (15), and an exhaust passage (29) that extends from an exhaust port (31). There are also a plurality of scavenge passages (27) which terminate in scavenge ports (28). The scavenge passages (27) interconnect the bore (15) and the combustion chamber (18). The scavenge passages (27) are formed by means of a pair of side covers (37) which are attached to the cylinder block (12) by means of a plurality of fasteners and a gasket (43). Suitable coolant enters via coolant passageway (44) and circulates through coolant passageways (33, 38, 50, 60).

Abstract: A two-cycle engine having a crank shaft, a main transmission shaft and a balancer shaft in order to lower the center of gravity and to improve lead valve layout is provided with a casing structure containing an intake passage formed integrally with a crank chamber and a transmission chamber and wherein the intake passage is located in a portion of the casing above the axes of the crank shaft and the main shaft and the balancer shaft is located below such axes.

Abstract: A two-cycle internal combustion engine comprising a cylinder including an exhaust outlet and scavenging paths formed in the inner wall thereof, and a piston including openings formed in its peripheral wall at positions near respective piston-pin bosses thereof, the respective upper ends of the scavenging paths serving as scavenging ports which are opened and closed through reciprocating movement of the piston and the openings being so arranged as to communicate with the scavenging paths at positions nearer to the exhaust outlet of the cylinder.

Abstract: Disclosed herein is an internal combustion engine comprising first and second cylinders, first and second crankcases extending respectively from the first and second cylinders, a crankshaft extending through the first and second crankcases, first and second pistons connected to the crankshaft to afford opposite action of the pistons and respectively reciprocally movable in the first and second cylinders to define first and second combustion chambers respectively communicable, subject to piston movement, with the first and second crankcases, first and second air induction passages respectively including first and second reed valves for respectively supplying air to the first and second crankcases, a duct extending between the first and second crankcases, and a valve located in the duct and movable between open and closed positions to respectively permit and prevent fluid flow between the first and second crankcases.

Abstract: A multi-cylinder engine block for an engine operating on the two-stroke cycle and having two or more adjacent cylinder bores (10,11,12) with the axes of the bores parallel and in a common longitudinal plane. Each cylinder bore having an exhaust port (20), and an exhaust passage (21) extending from each exhaust port (20) to an external surface (22) of the block in a direction generally at right angles to said common longitudinal plane (25). Two transfer ports (27,28) being provided communicating with the same cylinder bore on either side of the exhaust port in the direction of said common longitudinal plane. Each transfer port communicating with a respective transfer passage. The transfer ports (27,28) not extending beyond the common longitudinal plane (25), and the transfer passages (26,23) adjacent the respective transfer ports (27,28) extending in a direction generally tangential to the cylinder bore.

Abstract: A two-cycle internal combustion engine capable of improving its output and a rate of feed consumption. In the engine, an ignition plug is so disposed that its tip end is arranged in a top chamber and positioned on a vertical plane extending through the top chamber and a partition is provided in a region of the top chamber apart from the ignition plug in a manner to extend substantially along the vertical plane from one end of the top chamber by a distance toward the ignition plug, to thereby divide the region into two compartments. The partition cooperates with the top chamber to form corners to both sides of the one end of the top chamber with the partition being interposed therebetween so that they may serve to direct fuel gas supplied to the top chamber toward the ignition plug.

Abstract: A cylinder head for internal combustion engines for motor vehicles is provided with intake and exhaust manifolds formed integrally by casting and is arranged for the selective application of the fuel supply and ignition members typical of Otto-cycle or Diesel-cycle internal combustion engines respectively.

Abstract: A high power, fuel efficient, low-emission, four-stroke, 6 cycle method of operation. A primary intake conduit carries air or a lean mixture from the compression chamber (crankcase) to the combustion chamber. Fuel is added to the air or lean mixture as it passes through the intake conduit. A secondary intake conduit runs from the compression chamber to ports in the cylinder located slightly above the bottom dead center position of the piston. Supplemental air or lean mixture from the compression chamber is fed to the combustion chamber through the secondary conduit when the piston is near its bottom dead center position. While the piston is in its bottom dead center position between its intake and compression strokes, the air or lean mixture from compression chamber provides a stratified charge in the combustion chamber, which is far more efficient than a homogeneous mixture, and has the further benefit of filling the cylinder from the bottom as well as from the top.