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: To provide a 2-stroke cycle internal combustion engine for a vehicle in which less blowoff of a gas mixture occurs in a combustion chamber, fuel consumption is low and high exhaust gas purifying performance is attained. The cylinder of the internal combustion engine is slightly inclined toward the forward side of the vehicle body from its upright position. The high pressure chamber and the communication passages are arranged forwardly toward the vehicle body from the cylinder. Openings of the communicating passages toward the combustion chamber are arranged, from the scavenging port, near the combustion chamber. The intake control valve rotated from the crank chamber near the openings of the communicating passages toward the combustion chamber is arranged near the openings of the communicating passages, and the exhaust pipe and the exhaust expansion chamber communicating with the exhaust gas passage of the internal combustion engine are arranged at a rear part of the vehicle body from the cylinder.

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: A two-cycle engine for boosting intake pressure for higher performance per displacement. The two-cycle engine includes a crankcase having a blower housing and a crankshaft therein extending through the blower housing. The blower housing has an intake opening and a discharge opening. An impeller is disposed around the crankshaft. At least one cylinder is provided with a corresponding piston therein. The cylinder has an exhaust port located on a side wall of the cylinder. An intake conduit extends along the side wall of the cylinder in a spiral rising towards the top of the cylinder and passing beneath the exhaust port to terminate at a pair of intake ports in the side wall of the cylinder. A boost plenum has an intake tube fluidly connecting the discharge opening of the blower housing to the boost plenum. The boost plenum also has a discharge tube fluidly connecting the boost plenum to the intake conduit.

Abstract: A cylinder block for an internal combustion engine includes a mounting surface having therein a crankcase cavity and a pair of cylinders respectively extending from the cavity in acute angular relation to each other and each including a cylinder wall. The cylinder walls include outer ends having cylinder head mounting surfaces, mixture transfer ports, mixture supply ports, gas discharge ports and a main exhaust gas discharge passage. A passage communicates between the exhaust gas discharge ports and with the main exhaust gas discharge passage. Mixture supply passages extend between the mounting surface and the cylinder head mounting surfaces and include reed valves. Branch passages communicate between the transfer ports in the cylinder walls and the mixture supply passages at respective locations between the cylinder head mounting surfaces and the reed valves. Auxiliary supply passages extend from the mounting surface and communicate with the mixture supply ports in the cylinder walls.

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: A two-cycle engine having an enclosed crankcase assembly and a cylinder assembly. A cylinder wall is sized to sealingly cooperate with the piston as it reciprocates relative thereto. The cylinder assembly is provided with an exhaust port in a first plane and a pair of diametrically opposed recessed transfer ports positioned in a second plane along the cylinder axis. The cylinder assembly is provided with a pair of decompression slots each formed in the cylinder wall in communication with one of the opposed transfer ports and extending towards the combustion chamber end of the cylinder assembly. The decompression slots having a circumferential width W which is substantially constant and a radially measured depth D which varies generally linearly from a maximum depth at the intersection of the decompression slot and the transfer port to a minimum depth at the uppermost end of the decompression slot.

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: A cylinder for a two-cycle internal combustion engine is disclosed which enables reduction of HC in exhaust gas to be effectively attained without any complicated modification. A pair of scavenging ports 20, 20 are oppositely formed which employ loop scavenging mode towards the direction opposite to an exhaust port 16 symmetrically with respect to the longitudinal section F bisecting the exhaust port 16. A pocket portion 20c is formed at the innermost end of the inner surface 20a of the end portion closer to the exhaust port 16 of each of the scavenging ports 20, 20 to form a prolonged wall portion 20d extending along the inner wall surface 5 of the cylinder 1 in the direction apart from the exhaust port 16.

Abstract: A two-stroke engine comprising a crankshaft rotating around a first axis of rotation and having at least one balancing mass, a controller for controlling feeding of at least one combustion chamber of the engine. A second shaft is rotatable around a second axis of rotation parallel to the first axis of rotation and is rotatably driven by the crankshaft. At least one balancing mass is connected in rotation to the controller so as to achieve a first order balancing of the reciprocating masses of the engine. A pneumatic fuel injection system, utilizing a portion of an air charge of the engine, sprays fuel into the combustion chamber at predetermined times of a working cycle, and a counter rotating drive of the pneumatic injection controller means by the crankshaft is achieved by a two-space toothed belt.

Abstract: The invention relates to a gas-exchanging process for two-stroke internal combustion engines, and a two-stroke internal combustion engine for executing the process, in which two scavenging paths of the gas are provided, namely the known reverse scavenging as the first scavenging path, and a second supply of combustion air effected by precompression serving as the second scavenging path, wherein during the second scavenging an ignitable fuel-air mixture forms in the area of the point of ignition and, by means of the differential pressure established at the intake valve, controls the mixture as well as the quantity itself.

Abstract: A scavenge system for a two cycle internal combustion engine that includes separate scavenge manifolds and riser scavenge passages extending therefrom to the individual scavenge ports so as to permit the establishment of a desired flow pattern within the engine without the flow to one scavenge port interfering with the flow to the other scavenge ports.

Abstract: A two-stroke internal combustion engine is provided with a cylinder and a piston reciprocatingly mounted in the cylinder; the cylinder has two inlet ducts each having a inlet port opening into the cylinder for delivering a inlet strain to the cylinder and an exhaust duct having an exhaust port opening in the cylinder for removing an exhaust product from the cylinder with the inlet ducts and ports disposed so that the inlet stream impacts the wall of the cylinder at a substantially identical location between the exhaust port and an end of the cylinder opposite the piston with the inlet ports and exhaust ports arranged to eliminate crossing of the inlet streams and the exhaust stream.

Abstract: The invention relates to new and useful improvements in dual-cycle engine design and construction. The invention enhances the mechanical ability of such engines to automatically match the engine cycle with the load conditions while the system is in operation in a manner which significantly reduces the specific fuel consumption. Using the standard L-head engine configuration, the upper cylinder manifolding and the lower cylinder manifolding are combined as single flow channels reducing the number of components required to sequence flow to and from the engine. Combining the upper and lower cylinder manifold circuits standardizes the operating pressures in each system improving exhaust gas ejector efficiencies, facilitating engine control, and simplifying the application of pressure boosting in the air induction circuit. These improvements reduce the design complexity and simplify the automatic transition from 4-stroke to 2-stroke operation.

Abstract: Two embodiments of multiple cylinder two cycle internal combustion engines embodying scavenge manifolds that extend around the cylinder bores and which communicate with the cylinder bores through a plurality of circumferentially spaced scavenge ports. The scavenge ports are arranged so that a charge issuing therefrom is not directed toward the exhaust port and the scavenge ports are staggered so as to permit common scavenge manifolds between adjacent cylinder bores to reduce the length of the engine without adversely effecting its breathing ability.

Abstract: An internal combustion engine comprising an engine block defining a cylinder bore and including an exhaust passage communicating with the cylinder bore, a cylinder liner which is housed in the cylinder bore and which includes an exhaust port communicating with the engine block exhaust passage, and structure on one of the engine block and the cylinder liner for permitting one of the engine block and the cylinder liner to expand adjacent the exhaust port.

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 cylinder for an internal-combustion two-stroke engine, having multiple intake ports, multiple intake valve ports and multiple exhaust ports. The cylinder enables a two-stroke engine to run on gasoline without premixing it with lubricating oil and, due to its optimal volumetric efficiency and good separation of air-fuel mixture and exhaust gases, provides the possibility to satisfy requirements for high fuel efficiency, high power output and low emissions released into the atmosphere. An engine using this cylinder construction will be lightweight, will not require valve trains and camshaft and can be manufactured with any number of cylinders. Utilizing a slightly different process and slightly different configuration, the present invention will also enable a two-stroke engine to run on diesel fuel and produce significant benefits in comparison to existing two-stroke diesel engines.

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 wherein the scavenging gas is heated at low loads to improve scavenging. The gas may be heated by passage through finned passages in heat exchange relation with the exhaust ports with valves to direct the flow through unheated passages during higher load operation.

Abstract: A two-stroke cycle internal combustion engine without crankcase scavenging is disclosed which is able to operate in a four-stroke mode at cranking and idle speeds. The engine utilizes a turbocharger driven by exhaust gases to recharge the cylinder with fresh air or an air/fuel mixture. An auxiliary inlet valve responsive to pressure within the cylinder enables the engine to operate in a four-stroke mode, thus eliminating the need for an externally driven air pump when the engine is either idling, being started, or under light loads where turbocharger boost is too low to supply sufficient flow of air or an air/fuel mixture.

Abstract: The present invention relates to a combustion chamber in which two flows of gas are admitted via ports at the bottom of the cylinder, one of the flows being a mixture containing fuel and the other being a flow of pure air. These flows are admitted so that they meet inside the chamber close to the wall opposite from an exhaust port (5) so that the mixture is confined and slowed down in a cavity (9) in the cylinder head while the flow of pure air is split by an edge (12) formed between said cavity and the bottom wall (11) of the cylinder head so that one portion of this air flow returns and scavenges the combustion chamber (1).

Abstract: A method and system, including a valve (32) for controlling the amount of fluid purged from a cylinder (12) of a two-cycle engine prior to the combustion of an air-fuel mixture within the cylinder especially during low demand periods of engine operation. The system including a throttle (26) disposed upstream of an inlet port (14) and controlled to be maintained in an open condition during such intervals. The valve (32), which is adapted to communicate with a scavenge port (30) includes a piston (80) that is movable relative to an aperature (76) in response to a pressure differential created in part by the operation of a cooperating electromagnetic valve (54), such that when the piston is moved to uncover the aperture a predeterminable amount of fluid within the cylinder can be purged therefrom as the cylinder piston is moved through its compression cycle.

Abstract: Disclosed is a two-stroke engine having a central scavenging system through which the scavenging mixture, regulated into a single stream at a scavenging port provided in the top wall of the piston, jets upwardly into the center of the top portion of the cylinder bore and then spreads radially outwards so as to provide a plurality of currents of scavenging mixture. These currents branch from the main stream of scavenging mixture and flow through shorter distance as well as undergo similar flow environment with respect to one another due to symmetry in regard to the center of the cylinder. Thus, the scavenging performance of the two-stroke engine can be greatly improved.

Abstract: A cooling system for a two-stroke engine including a water jacketed cylinder having cooling passages located beneath the exhaust port and beneath the transfer ports in the cylinder wall. Liquid coolant flows upwardly from the crankcase structure into the cylinder wall cooling jacket and finally upwardly into the head.

Abstract: A two-cycle internal combustion engine having an oblong cylinder and an oblong piston therein. The engine includes two sets of scavenging ports at either end of the oblong cylinder having at least three ports each. Scavenging passages extending to the scavenging ports may be directed at sequentially increasing angles of inclination to the local normal with the cylinder away from the exhaust porting. In this way, flow may be directed across the piston head away from the exhaust porting and then upwardly to return toward the exhaust porting. A domed piston is also disclosed having discrete guide surfaces on the domed surface of the piston to specifically direct incoming air/fuel mixture upwardly from each of the scavenging ports. An element of the cylinder midway in the long dimension of the cylinder extends in the direction of piston movement without porting so as to provide a smooth wall surface.

Abstract: A two cycle internal combustion piston engine is provided with cam controlled inlet valves, as well as exhaust valves, disposed in the head of the engine cylinder. The two cycle engine can perform with an expansion ratio greater than the compression ratio. A standard two cycle internal combustion piston engine can be converted to the inventive two cycle engine construction by replacing the conventional engine cylinder head, replacing the conventional engine valve cam shaft, and directing air flow in the intake manifold to one side of the replacement cylinder head.

Abstract: In the case of a high-speed, port-controlled two-stroke internal combustion engine with crankcase scavenging with at least one cylinder having in each case at least one suction duct with an inlet port, with in each case at least one outlet duct with an outlet port and with at least one scavenging duct with a transfer port, the inlet, outlet and transfer ports being arranged on the cylinder inside, the geometrical construction of the suction duct (4) and/or outlet duct (6) is such that the engine noise is reduced throughout the speed range, while increasing the engine efficiency and while simultaneously improving the specific fuel consumption.

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: A deflector piston two stroke internal combustion engine has a piston (10) reciprocable in a cylinder and sealed thereto by means of piston rings (P2), the cylinder having communicating with it a scavenge part SC2) and an exhaust part (E2). The piston crown has an upper first planar surface lying at right angles to the piston cylinder axis and a lower parallel planar surface, these two surfaces being connected by a deflector edge (D). The upper planar surface co-operates, at or near top-dead-center with a complementary planar surface on the interior (underside as shown) of the cylinder head with which it has a minimum clearance C2. The approach of these surfaces as top-dead-center is approached generates a "squish" that is a jet of fuel/air mixture in the direction of arrow (S2) towards the spark plug which improves combustion.

Abstract: The two-cycle internal combustion engine has a crankcase, a combustion chamber including an exhaust port, a fuel intake port and a pair of air-intake ports located on the opposite sides of the fuel intake port, and a piston movable relative to the combustion chamber between top dead center and bottom dead center positions. The crankcase has separate air and fuel inlets and includes interior portions defining an air crankcase portion which communicates with the crankcase air inlet and with two air transfer passages which communicated with the air intake ports and a separate fuel crankcase portion which communicates with the crankcase fuel inlet and a fuel transfer passage which communicates with the fuel intake port. Air is drawn through the crankcase air inlet into the air crankcase portion and a fuel-air mixture is drawn through the crankcase fuel inlet into the fuel crankcase portion during the upstroke of the piston toward top dead center.

Abstract: A two-stroke cycle gasoline engine, comprising a power cylinder-piston assembly having a scavenging port configuration including a first scavenging port configuration first uncovered by the power piston as it moves along the power cylinder from its top dead center to its bottom dead center and a second scavenging port configuration uncovered by the power piston as it moves from its top dead center to its bottom dead center immediately after said power piston has completed uncovering the first scavenging port configuration, wherein the general rate relative to piston position in the power cylinder of uncovering of the area of the first scavenging port configuration is substantially lower than that of the second scavenging port configuration, so that the idling and low-load performance of the engine is substantially improved by improving scavenging.

Abstract: A method and apparatus is disclosed for decreasing fuel consumption in a variably loaded, two cycle internal combustion engine. Fluid communication is provided between the working cylinder and air chamber during the upward stroke of the engine up to about 85.degree.-105.degree. BTDC, during which time the cylinder gases can flow back into the air chamber reducing engine friction as a result of a delay in the rise of the cylinder gas pressure during compression and a reduction in the peak compression pressure.

Abstract: A front transfer port system to help ensure a regular cooling of the piston and cylinder temperature at the points where the heat conditions are more severe, and to improve the transfer process of the mixture that transfers from the crankcase to the cylinder with more scavenging efficiency to displace spent products to the atmosphere through the exhaust ports in an internal combustion two-stroke cycle engine. The front transfer port system is situated in the cylinder wall at the front and between the exhaust ports.

Abstract: An internal combustion engine comprises a combustion chamber and a piston movable relative to the combustion chamber between top dead center and bottom dead center positions. A fuel transfer passage introduces fuel-air mixture into the combustion chamber in response to piston movement. An auxiliary chamber is also provided which is communicable with the combustion chamber in response to piston movement shortly after the ignition of a fuel-air mixture, such that high pressure ignition gases enter the auxiliary chamber. The high pressure ignition gases thereafter flow back into the combustion chamber in response to piston movement before communication is established between the combustion chamber and the fuel transfer passage. The incoming flow of high pressure ignition gases serves to influence the normal scavenging streams.

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: A method for operating a two-cycle internal combustion engine wherein in the scavenging stroke the air-fuel mixture charged into the cylinder forms a stratum adjacent to a piston and the stratum of the air-fuel mixture is made into contact with the stratum of the residual gases remote from the piston. Alternately, in the scavenging stroke the rich mixture is first charged into the cylinder immediately above the piston and then the lean mixture is charged into the cylinder immediately above the piston so that the strata of the lean and rich mixtures and the residual gases may be formed in the order named from a portion close to the piston within the cylinder. The decomposition of part of the air-fuel mixture or the rich air-fuel mixture is caused by the heat contained in the residual gases so that the chemically activated radicals are produced.

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: An improved multicylinder internal combustion engine is described for efficiently producing power. The internal combustion engine described is fuel injected with a stoichiometric fuel mixture to develop a stratified charge suitable for igniting a leaner mixture of fuel and air. The charge is advantageously introduced into two adjacent cylinders for igniting a fuel mixture common to both cylinders. Improved fuel injection and super charging of the internal combustion engine is also described herein.

Abstract: A two-stroke cycle gasoline engine including at least one two-stroke cycle power cylinder - piston assembly incorporating uniflow scavenging and two horizontally opposed pistons, and a scavenging structure which gives zero or a relatively weak swirl to the scavenging mixture ejected into the power cylinder so as to effect stratified scavenging of exhaust gases when the engine is operating at relatively low load and which gives a relatively strong swirl to the scavenging mixture ejected into the power cylinder so as to cause high turbulence in the mixture when the engine is operating at relatively high load.

Abstract: A two-stroke cycle diesel engine having at least one two-stroke cycle power cylinder-piston assembly incorporating uniflow scavenging and having two horizontally opposed pistons, at least first and second scavenging ports and two crankcases which may perform crankcase compression; a pump assembly including at least one scavenging pump cylinder-piston assembly of the reciprocating type which is separate from and is driven by the power cylinder-piston assembly; a scavenging air introducing device which introduces scavenging air compressed by the pump assembly to the first and the second scavenging ports through first and second passage systems, respectively; and a fume generating device incorporated in the second passage system and supplying fuel mist in an initial part of the air supplied through the second passage system; wherein the fume is supplied as stratified with exhaust gases so as to be heated by the exhaust gases toward decomposition and then the first passage system is interrupted before the pump as

Abstract: A two-cycle internal combustion engine includes a cylinder, a piston in the cylinder and a crankcase pump. The crankcase pump is divided into a first chamber and a second chamber by a membrane. At least one respective transfer passage connects each of the respective chambers to the cylinder. Inlets are provided for admitting pure air into the first chamber and for admitting carbureted air into the second chamber. Devices are provided for opening that one of the transfer passages communicating between the cylinder and the first chamber first and thereafter for opening the one of the transfer passages communicating between said cylinder and said second chamber during operation of the engine.

Abstract: A two-stroke cycle diesel engine having: at least one two-stroke cycle power cylinder - piston assembly incorporating uniflow scavenging and having two horizontally opposed pistons, at least first and second scavenging ports and two crankcases which may perform crankcase compression; a pump assembly including at least one scavenging pump cylinder - piston assembly of the reciprocating type which is separate from and is driven by the power cylinder - piston assembly; and a scavenging air introducing device which introduces scavenging air compressed by the pump assembly to the first and the second scavenging ports through first and second passage systems, respectively; wherein the first passage system is interrupted before the pump assembly reaches its top dead center so that thereafter the scavenging air compressed by the pump assembly is all supplied to the second scavenging port which is adapted to generate strong swirl flows in the power cylinder when scavenging air at high pressure is supplied in a large a

Abstract: A two-cycle engine including first set of passages formed outside a cylinder connecting a first crank case with scavenging ports for feeding air-fuel mixtures from the first crank case to the cylinder, second set of passages formed outside the cylinder connecting a second crank case with the scavenging ports for feeding air-fuel mixtures from the second crank case to the cylinder, and scavenging gas merging chamber cooperative with the first and second sets of passages and located upstream of the scavenging ports for restricting flow of air-fuel mixtures in vicinity of the scavenging ports. First and second pistons are mounted in opposed relation to each other in the cylinder, the first piston opening and closing an exhaust port and the second piston opening and closing the scavenging ports.

Abstract: A two-stroke cycle engine is provided with valveless exhaust and inlet ports in a cylinder wall. A piston is mounted for reciprocal movement in the cylinder. A precombustion chamber is formed in the piston, which communicates with the combustion chamber above the piston by a relatively large aperture adapted to receive the end of a spark plug. When the piston is at the bottom of its stroke, pressurized fresh air is supplied through the inlet ports for purposes of scavenging the combustion chamber and filling it with fresh air. There is also provided means for forcing a charge of rich fuel-air mixture into the precombustion chamber. The aperture providing communication between the precombustion chamber and the combustion chamber is sufficiently large that a desired amount of fuel can be ejected into the combustion chamber. During the compression stroke of the piston, the fuel-air mixtures in the precombustion chamber and in the combustion chamber are compressed.

Abstract: A method of bevelling the peripheral edges of port openings on the inner wall of cylinders for two-cycle engines. At least the upper and lower edges of the port opening on the inner wall of a cylinder are shaped, in advance when casting the cylinder, into concavities arcuately recessed in both axial and radial directions of the cylinder. The boundary edges between the recessed concavities and the inner wall of the cylinder are lightly bevelled by pressing or grinding so that an excellent workability, mass-productivity, and great precision can be attained.

Abstract: Disclosed are intake and exhaust assemblies for forced air intake, reciprocating piston, internal combustion engine. Alternate embodiments of the air intake valve assembly include a hollow tube defining the intake port with means operatively coupling the tube and piston to respectively open and close the intake port in response to the reciprocation of the piston. The exhaust valve assembly includes operatively interrelated valve stem, spring retainer, rocker arm, and camming assemblies for alternatingly opening and closing the exhaust port for predetermined time intervals.

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: A single-piston or multi-piston two-stroke internal combustion engine for introducing into the working space or working spaces of the one cylinder or of the several cylinders respectively a pressurized fluid such as a gas, ambient air or a gaseous mixture or a mixture of a gaseous medium and a liquid at approximately an intermediate height of the cylinder working space between top and bottom dead center positions of the piston head surface for separating inflowing fuel-air mixture from the exiting combustion gases and for establishing a layer charge overlying the piston head. The two-stroke engine is provided with an additional inlet port for admitting this additional pressurized fluid into the cylinder working space, the inlet port being in communication with fluid supply means and optionally including an automatically pressure operated or positively actuated control member.