Abstract: A fuel-injection arrangement and a two-stroke engine define a combination for a portable handheld work apparatus such as a motor-driven chain saw or the like. The combination includes a fuel-feed pump for pumping fuel from a fuel tank and a fuel-injection pump for supplying the fuel for injection into the engine. The fuel-feed pump and the fuel-injection pump are mounted in a con, non injection-pump block separate from the engine. The engine has an intake channel through which combustion air is drawn into the engine and the intake channel is configured so as to open directly into the engine. A throttle flap is pivotally mounted in the intake channel as to be completely separate from the common injection-pump block. The injection pump block is effectively thermally decoupled from the intake channel. The danger of vapor bubble formation because of a heating of the injection pump is thereby reliably avoided.

Abstract: For fuel injection control in a cylinder direct-injection engine, fuel injection beginnings for injecting fuel successively into a plurality of cylinders are calculated; threshold voltage impression beginnings at which a threshold voltage for starting to inject the fuel from injectors is applied are calculated, corresponding to the fuel injection beginnings, and the ends of the threshold voltage impression are calculated; it is determined whether or not a first period between the beginning and end of threshold voltage impression for a preceding cylinder is coincident with a second period between the beginning and end of threshold voltage impression for a succeeding cylinder; and the second period is modified so as to be earlier or later than the first period, if the two periods are coincident with each other.

Abstract: The fuel injected two-cycle internal combustion engine having an exhaust control valve and direct cylinder injection. The fuel injection timing and duration are increased at starting over idle and the exhaust control valve, which is normally closed at idle and opened at high speed is moved to its high speed condition during starting to assist in starting. In addition, when the engine is returned to an idle condition after racing, the engine idle speed is reduced in steps to prevent stalling and improve return to idle.

Abstract: Apparatus for imparting a spiral spin on a fluid in zone 2 surrounding a columnar substance in zone 1 which may be a metal electrode or a fluid, such as gas for welding. The spirally spinning fluid may be an inert gas for sheathing zone 1 down to the welding site on a workpiece. For a four-stroke-cycle internal combustion engine, exhaust gas return (EGR) in zone 1 is sheathed from a fuel-air mixture in zone 3 by the spirally spinning fluid (fresh air) in zone 2. In a two-stroke-cycle engine, the spirally spinning fluid in zone 2 may be injected gas while the EGR is injected in zone 1. Fresh air, precharged in the cylinder at the end of the power stroke, constitutes zone 3.

Abstract: A two-stage fuel delivery system for an internal combustion engine that includes a first stage pump having a first pump chamber with an inlet coupled to a fuel source, an outlet and a diaphragm responsive to pressure pulsations from the engine crankcase for reciprocation within the chamber. A second stage pump includes a second pump chamber having an inlet coupled to the outlet of the first chamber, an outlet for delivering fuel under pressure to engine fuel injectors or the like, a permanent magnet for mounting on the flywheel of the engine for rotation in synchronism with operation of the engine, and a diaphragm in the second chamber operatively coupled to the magnet for reciprocation with the second chamber responsive to rotation of the magnet to pump fuel from the inlet to the outlet of the second chamber.

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: The invention is directed to a membrane fuel pump for a membrane carburetor of an internal combustion engine. The carburetor has a pressure controller and the engine has a crankcase wherein pressure fluctuates during the operation thereof. The membrane fuel pump includes a pump membrane mounted in a housing which partitions a space of the housing into a pump chamber for receiving fuel from a fuel supply connection and a drive chamber. The drive chamber is charged with the pressure of the crankcase. A pressure connection connects the pump chamber to the pressure controller of the membrane carburetor. A bypass channel connects the pressure connection to the fuel supply connection and a valve is interposed between the pressure connection and the bypass channel.

Abstract: An intermittent fuel-injection method for two-stroke engine, which is done by means of an injection nozzle mounted under a cylinder head or on cylinder wall so as to have fuel directly injected into a cylinder to mix the air inside the cylinder into a homogeneous mixture; a controller is used for controlling the fuel-injection timing and quantity; the controller determines the injection timing and quantity in accordance with the engine intake air flow quantity and engine rpm; under idle running or low-load running condition, an intermittent fuel-injection control method is used so as to enable an engine to perform one, two, three, four or five scavenging and exhaust cycles after one fuel-injection cycle in order to obtain a steady and high combustion efficiency.

Abstract: A two-stroke internal combustion engine comprising a combustion chamber, a fuel injector for injecting fuel into the combustion chamber, an intake passage communicating with the combustion chamber, the intake passage including a venturi section, a throttle in the intake passage, and an engine control for sensing the pressure P.sub.V in the venturi section during engine operation, for sensing throttle position TP, for determining, in response to TP, a specific amount of fuel to be injected by the fuel injector, and for modifying the specific amount of fuel in response to P.sub.V.

Abstract: A motorcycle powered by a two cycle crankcase compression fuel injected internal combustion engine. The injection system for the engine includes a main fuel air/injector that injects fuel directly into the combustion chamber and a second or auxiliary fuel injector that injects fuel into the induction system for the engine. Control means control the fuel injectors so that the second or auxiliary fuel injector supplies fuel only during starting and high load, high speed conditions. The engine components are laid out in such a way that the spark plugs of the engine and the fuel injector will each be exposed to unobstructed air flow for cooling.

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: Two embodiments of crankcase compression, internal combustion engines have air/fuel injection systems that include an air compressor driven by the engine and protected by the intake manifold. In one embodiment, the air compressor also drives a water pump and in both embodiments the induction system is designed so as to maintain substantially equal length runners for the individual crankcase chambers. This is accomplished by forming the check valves the communicate the runners with the crankcase chambers in parallel relationship to the respective runners.

Abstract: Several embodiments of fuel injected engines wherein stability and running is achieved by maintaining an injection velocity that is greater than the velocity of the charge in the chamber including that component contributed by the squish action in the engine and at least equal to 40 meters per second so as to ensure effective stratification and the existence of a stoichiometric charge at the spark plugs at the time of ignition, even under low load and speed conditions such as idle.

Abstract: The invention is directed to a fuel injection pump for a two-stroke engine mounted in a work apparatus such as a motor-driven chain saw. The injection pump includes a pneumatic drive chamber which is charged with the crankcase pressure of the two-stroke engine. A membrane mounted in the drive chamber transmits the pulses of the crankcase pressure to a pump piston which moves into a pump chamber against the force of a leaf spring. The leaf spring is configured as a leaf spring packet of individual leaf springs in order to obtain an adaptation of the injected fuel quantity to the position of the throttle flap of the engine.

Abstract: The invention is directed to a fuel injection pump for a two-stroke engine which is especially for portable handheld tools such as motor-driven chain saws or the like. A pneumatic drive chamber is provided in the pump housing which is partitioned by a membrane into a pulse chamber charged by the crankcase pressure and a return chamber. A membrane plate holds the membrane and charges a pump piston which plunges into a pump cylinder for injecting fuel when a pulse is present in the pulse chamber. The pump piston draws fuel in by suction during a return stroke of the membrane plate into a start position determined by a stop. The stop is configured so as to be displaceable in the direction of the stroke of the piston in dependence upon temperature in order to obtain an adaptation of the injected quantity of fuel to the operating temperature of the engine. In this way, the stroke of the pump piston can be varied and therefore also the quantity of fuel supplied by the pump.

Abstract: Two embodiments of fuel injection systems for two cycle crankcase compression internal combustion engines that employ two fuel injectors. One fuel injector injects into the combustion chamber while another injects into the induction system of the engine. A simplified regulating system is incorporated so that the first injector receives fuel under a higher pressure than the second injector.

Abstract: A fuel injection system for engines for improving performance and fuel economy. The fuel injector controlled along with an exhaust port timing control mechanism so that fuel injected into the engine will not pass out of the exhaust port under most engine running conditions. The invention is disclosed particularly in conjunction with a two cycle crankcase compression engine wherein it has particular utility. The timing of the opening and closing of the exhaust port is changed by means of an exhaust control valve that obstructs the exhaust port under certain running conditions so as to delay its opening and closing.

Abstract: A first fuel injection pulse width is provided based on engine operating conditions. The amount of fuel is necessary for one combustion stroke of the engine at one time. A second fuel injection pulse width is provided based on engine operating conditions so as to inject at one time an amount of fuel for two combustion strokes of the engine. The first fuel injection pulse width is compared with a minimum value. The first fuel injection pulse width is selected when the first fuel injection pulse width is larger than the minimum value, and otherwise, the second fuel injection pulse width is selected when the first fuel injection pulse width is smaller than the minimum value. Fuel is injected at the selected injection pulse.

Abstract: A diesel engine operating on the two cycle crankcase compression principle and having a means for reducing nitrous oxide emissions under low and medium range speeds. This is done by throttling the scavenge air flow which can be accomplished either by throttling the air admitted to the crankcase chamber or bypassing a portion of the compressed air from the crankcase chamber back to the induction system. In addition, an exhaust control valve is provided for raising the compression ratio and the injection timing is advanced when the scavenge air is reduced so as to further improve the control of hydrocarbon and carbon monoxide emissions.

Abstract: An improved method of operating a two cycle direct injected internal combustion engine so as to provide good ignition and combustion even when operating in a stratified condition. This is achieved either by extending the duration of firing of the spark plug either by extending a single firing or providing multiple firings per cycle or by changing the energy level across the gap of the spark plug during its firing.

Abstract: A fuel injection control system for a two cycle crankcase compression internal combustion engine that employs two sensors for sensing engine load. One of the sensor, a throttle valve position sensor, is more sensitive at low speed and low load conditions and the other of the sensor, a crankcase pressure sensor, is more sensitive under high speed and high load conditions. The output of the fuel injectors is controlled by a map ratio showing the input signals from the two sensors in response to their areas of greatest selectivity.

Abstract: A fuel injection system for a two cycle crankcase compression internal combustion engine including a first injector that supplies fuel directly to the combustion chamber of the engine. An induction system is provided for inducting air into the crankcase chamber of the engine and in a multiple cylinder engine this includes a manifold having a single inlet. A throttle body having a throttle valve controls the flow of air through the inlet and a second fuel injector sprays fuel into the throttle body upstream of the throttle valve and against the throttle valve in certain positions of the throttle valve. In accordance with one disclosed embodiment of the invention, the second fuel injector supplies the fuel requirements for maximum power while the first fuel injector supplies the fuel requirements for low and mid range performance, but does not have adequate capacity to supply all of the fuel for high range performance.

Abstract: This invention relates to a fuel injection apparatus for an internal combustion engine, and more particularly to an improved control arrangement for a fuel injection arrangement. In accordance with the invention, an arrangement is disclosed for determining the mass of air taken into the engine crankcase chamber by calculating an average intake air mass which is based not on pressure measurements taken upon each crankshaft rotation individually, but on the arithmetical mean of such pressure measurements taken during a plurality of crankshaft rotations. Thus, a fuel injection control system is achieved which senses differences in crankcase pressure and which eliminates the effects of abnormal changes in crankcase pressure due to effects other than the amount of air inducted.

Abstract: Method for operating an engine having a piston reciprocable in a cylinder, an intake port for admitting air, an exhaust valve controlled by a valve actuator independently of crankshaft position, spark ignition, and fuel injection. During a first stroke the piston moves from BDC to TDC, the intake port is closed, the exhaust valve is closed, and fuel is injected. During a second stroke (TDC to BDC) the exhaust valve remains closed, lowering the pressure and causing some evaporation of the fuel-air mixture. During a third stroke (BDC to TDC), the fuel air mixture is again increased and finally ignited. During a fourth stroke (TDC to BDC) the ignited mixture expands, followed by opening the exhaust valve and the intake port. The second and third strokes enhance evaporation thus permit ignition of low vapor pressure fuel in a cold engine. Once the engine is hot, the valve actuators permit transition to a two-stroke-cycle.

Abstract: A fuel air injection system for a multiple cylinder engine wherein an air manifold is rigidly affixed to all of the fuel air injectors so as to form a unitary assembly that can be removed from the engine as a unit.

Abstract: In a two cycle internal combustion engine (80) comprising three cylinders (22, 24, 26) vertically in-line, a single intake manifold (82) services all three of the cylinders, and a single fuel delivery device (84), such as a carburetor, on the manifold delivers fuel to each of the cylinders. Location and orientation of the three reed block openings (90, 92, 94) relative to each other and relative to the throttle bore (128) provide desired fuel distribution. Manifold structure, including internal dams (142, 146) and a deflector plate (138), prevents an overly rich fuel mixture in the lower cylinder (26) at idle, and prevents an overly rich fuel mixture in the upper cylinder (22) at running speeds above idle.

Abstract: Apparatus and method for operating a 2-stroke or 4-stroke reciprocating compression-ignition internal combustion engine, of the direct injection type, to reduce fuel consumption and to reduce NO.sub.x emissions. A staged fuel injection process involving two fuel injectors, but only one type of fuel, is used. A low pressure fuel injection device injects a pilot fuel charge into the combustion chamber when the combustion chamber is near its lowest pressure and its maximum volume. The pilot fuel charge stratifies within the combustion chamber, and undergoes a preflame reaction with a resultant release of heat energy. Near the end of the compression stroke of the piston, when the combustion chamber is near its minimum volume, a high pressure fuel injector injects a main fuel charge into the combustion chamber. The main fuel charge is ignited by the burning pilot fuel charge, and combustion of the main fuel charge is accelerated by the heat energy released by the pilot fuel charge preflame reaction.

Abstract: A two cycle crankcase compression internal combustion engine having a main air/fuel injection system for injecting fuel and air directly into the combustion chamber and an auxiliary injection system for injecting fuel into the engine upstream of the combustion chamber for cooling the piston. A variety of arrangements of control strategies and auxiliary injection nozzle positions are illustrated and described.

Abstract: When a two-stroke combustion engine (10) runs in the no-load or underload mode with intermittent fuel injection, besides the injection nozzles (12) being activated intermittently, the throttle (18) is opened more than is usual on transition into the no-load or underload mode and the fuel is simultaneously injected at a constant angle of aperture and flow. The process ensures reliable ignition of a weak mixture in the no-load or coasting mode; thus the energy consumption and exhaust production are limited in these modes and the engine runs in a cost-effective manner.

Abstract: A fuel injection system for a two cycle engine having main fuel injectors that inject directly into the engine combustion chambers and a sub or auxiliary fuel injector that injects into the induction system only under high load conditions to effect better piston cooling. Once the sub fuel injector begin to inject, then the amount of fuel per cycle injected by the main fuel injectors is decreased. The sub injector injects into a common manifold for a multiple cylinder engine and injects only one per crankshaft revolution.

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 combustion chamber of an engine has a fuel injector provided for injecting fuel directly in the combustion chamber. A fuel injector and a gap of a spark plug are located on the axis of the cylinder of the engine. A fuel injection finishing crank angle is set at an angle to advance an ignition timing in accordance with an arrival time of a fuel spray at the tap, and a fuel injection starting angle with respect to the fuel injection finishing angle is set in accordance with a quantity of the injected fuel.

Abstract: A solenoid operated valve controls the pressure of fuel supplied to a fuel injector. The fuel pressure is determined in accordance with the engine operating conditions. A driver is provided for operating the solenoid operated valve for setting the fuel pressure. The fuel pressure is increased as the load on the engine increases.

Abstract: A two-stroke-cycle spark ignited internal combustion engine operates with an exhaust valve that is controlled independently of crankshaft position and optimally for high power and low pollutant output in combination with a scavenging pump and fuel injector. The volume of combustible mixture is established at the point in the cycle when the exhaust valve is selectably closed with the piston traveling upwardly and decreasing the volume of the cylinder. Throttling losses are eliminated since the piston forces the scavenging air out of the cylinder through the wide-open exhaust valve rather than the air being drawn into the cylinder against the reduced pressure caused by a conventional partially closed throttle plate. The volume of combustible air in the cylinder is determined by the point in the cycle at which the exhaust valve is closed and a correspondingly appropriate charge of fuel is thereafter injected into the cylinder.

Abstract: The invention is directed to an internal combustion engine for a portable handheld work apparatus with an intake pipe or induction elbow being attached to the cylinder. The engine can be a two-stroke engine having an inlet opening in the cylinder for the combustion mixture. A cylinder flange is provided at the inlet opening for connecting the induction elbow for conducting the combustion mixture. The induction elbow is made of rubber-elastic material and fits over the cylinder flange in a form-tight manner and is fixed thereto. The connecting end of the induction elbow is provided with an inner annular shoulder which engages an outer annular slot of the cylinder flange which is adapted with respect to volume and is reliably held by a clamp ring having a fixed diameter. The rubber-elastic material of the connecting end is compressed in the annular slot by the clamp ring thereby seating the induction elbow on the cylinder flange in such a manner that it cannot become disconnected.

Abstract: An in-line, two-cycle, crankcase compression, internal combustion engine having a plurality of scavenge ports and an exhaust port for each cylinder in which an exhaust control valve is positioned. To permit a compact assembly, the ports are rotated about the cylinder bore axis in a transverse plane so that the exhaust ports extend at an acute angle to a common plane containing the cylinder bore axes and the control shafts for the exhaust control valves extends perpendicularly to this plane. A wide variety of actuators are disclosed for operating the exhaust control valves simultaneously including flexible transmitters and a linkage system.

Abstract: An exhaust control valve arrangement for an in-line, two-cycle, crankcase compression engine which permits the porting arrangement to be rotated relative to the cylinder bore axis to achieve a compact configuration and wherein all of the exhaust control valves are operated by a single shaft assembly that extends parallel to a plane containing the cylinder bore axes. As a result of this orientation, the exhaust control valves provide an asymmetric exhaust port opening under at least some operative positions of the valves when the valves are in a flow obstructing position. A number of embodiments are disclosed which configure the exhaust control valves so that the port is symmetric in at least some operative obstructing positions of the valves. Also, several embodiments using curved valve configurations are disclosed.

Abstract: A two-stroke engine having an intake valve and an exhaust valve arranged on an inner wall of the cylinder head, an intake passage connected to the cylinder via the intake valve, a fuel injection device arranged in the cylinder, for injecting fuel into the cylinder, a pressure regulator for regulating a fuel pressure supplied to the fuel injection device on the basis of a scavenging pressure in the intake passage, to thereby increase the fuel pressure in accordance with an increase of the scavenging pressure, and a control device for controlling the injection of fuel by the fuel injection device for a time ranging from a time at which the intake valve is opened to a time at which the scavenging pressure becomes equal to a pressure in the cylinder after the intake valve is closed.

Abstract: A two-stroke internal combustion engine provided with a masking wall (8a, 40b) which is disposed between an intake valve (6) and exhaust valve (7) disposed on a cylinder head inner wall surface (3a) and which closes the opening between the peripheral edge of the intake valve (6) and valve seat (9) positioned at the exhaust valve (7) side, over the period of full opening of the intake valve (6), and a fuel injection valve (14, 42) which is disposed at the peripheral side portion of the cylinder head inner wall surface (3a) at the intake valve (6) side, wherein the fuel injection from the fuel injection valve (14, 42) to the cylinder (1) is started when the intake valve (6) opens. By this, it is possible to easily ignite the fuel and to stabilize the combustion after ignition.

Abstract: A two-cycle engine has a fuel injector provided for injecting fuel directly in a cylinder of the engine. An amount of air actually induced into the cylinder is calculated based on the amount of escape air and the amount of intake air detected by an air-flow meter. The quantity of fuel injected by the fuel injector is calculated based on the engine speed and the amount of air induced in the cylinder. The timing of the fuel injection is advanced as engine load increases and the duration of fuel injection increases as the engine load and engine speed increase.

Abstract: A method and means are described for determining the average backpressure at a cylinder exhaust port in a crankcase scavenged two-cycle engine. The exhaust backpressure is determined by averaging the pressure of air within a crankcase chamber associated with the cylinder, during a portion of the engine operating cycle when the cylinder inlet and exhaust ports are simultaneously open. The overlap interval in port openings creates a channel for airflow between the crankcase chamber and the cylinder exhaust port, and except for an initial portion of the interval assocated with the pressure equalization between the cylinder and its crankcase chamber, the crankcase pressure substantially equals the backpressure appearing at the cylinder exhaust port. In the preferred embodiment of the invention, a pressure sensor is disposed within the crankcase chamber to sample air pressure at specified engine rotational positions during the overlap interval.

Abstract: A temperature sensor is provided for detecting temperature of exhaust gas in an exhaust passage of a two-cycle engine. The temperature is compared with a reference temperature for activating a catalytic converter. When the temperature is lower than the reference temperature, the ignition timing and the fuel injection timing of the engine are retarded. The quantity of injected fuel is increased so as to compensate reduction of engine power caused by retarding the ignition timing.

Abstract: A two-stroke, two-cylinder internal combustion engine for use in portable applications has a cylinder head design, a fuel injection system and an ignition system which enables the engine to start and run on a fuel such as JP5 or DFM.

Abstract: A two-cycle engine having a fuel injector provided for injecting fuel directly in a combustion chamber. An offset cavity having a hemispherical shape in vertical section is formed at a top of the combustion chamber, and a spark plug is located at a top portion of the cavity. A fuel injector is located to inject fuel in the opposite direction to the discharge direction from an exhaust port. A recess is formed in a crown of a piston corresponding to the cavity and the fuel injector.

Abstract: Disclosed herein is an engine comprising an engine block, a crankshaft rotatably mounted on the engine block, having an axis, and including a cylindrical surface in excentric relation to the crankshaft axes, a plurality of cylinders supported by the engine block in a common plane and having respective axis extending radially from the crankshaft axis, which cylinders each have a radially outer end including an outlet valve, a plurality of pistons respectively movable in the cylinders, each of which pistons includes an air inlet valve, a plurality of connecting rods respectively pivotally connected to the pistons, and a drive hub rotatably mounted on the crankshaft surface and pivotally connected to the connecting rod such that crankshaft rotation causes reciprocation of the pistons in the cylinders and pumping of air into the cylinders through the inlet valves and out of the cylinders through the outlet valves.

Abstract: A multiple cylinder two-stroke fuel-injected internal combustion engine is operated at idle by interrupting the fuel injection stages in a predetermined pattern such that over a certain number of crankshaft revolutions a fewer number of injections occur than over the same number of revolutions at non-idle. The quantity of fuel injected per injection is increased relative to that required to operate the engine at idle wihtout any injection interruptions. Spark timing is also advanced.

Abstract: A two-stroke engine has a scavenge pump provided in an intake passage, and a fuel injector provided for injecting fuel directly into a cylinder of the engine. A sensor is provided in an exhaust passge for detecting the concentration of a component of the exhaust gas, thereby detecting the actual air-fuel ratio. A desired air-fuel ratio of exhaust gas including a part of scavenging air supplied by the scavenge pump is derived from a map. The actual air-fuel ratio is compared with the desired air-fuel ratio to produce an error signal. In accordance with the error signal, the quantity of fuel injected by the fuel injector is controlled so as to cause the actual air-fuel ratio to converge to the desired air-fuel ratio.

Abstract: A two-stroke-cycle uniflow spark-ignition engine. A fluid sucked and pressurized by a compressor driven by the engine is delivered to an annular scavenging chamber formed in a cylinder around the entire circumference thereof, so as to be accumulated therein. The fluid within the annular scavenging chamber is discharged therefrom, through a plurality of scavenging ports formed in the cylinder and capable of opening into a cylinder chamber toward the end of a descending stroke of a piston, and/or into a recess which is above the piston, the discharged fluid serving as a scavenging fluid that flows generating a swirling uniflow. A mixture compressed within the cylinder chamber during an ascending stroke of the piston is ignited by an ignition plug for combustion.

Abstract: A two-stroke engine comprises a cylinder which accommodates a piston and which has inlet and outlet ports, means for injecting fuel into the cylinder and control means for controlling the amount of fuel injected. The engine also includes a vent passage communicating with the interior of the cylinder and a first valve which is arranged to prevent communication between the interior of the cylinder and the vent passage and is connected to be opened and closed in synchronism with movement of the piston. Situated in the vent passage downstream of the first valve is a second throttling valve which is coupled to the control means and is arranged to be opened to an increasing extent to permit an increasing proportion of the inlet charge to be discharged as the control means is operated to reduce the amount of fuel which is injected into the cylinder thereby achieving homogeneous combustion at a constant air fuel ratio.

Abstract: A method and apparatus for improving the output torque response of a crankase scavenged, two-stroke engine to a change in throttle position by adjusting the conventional timing of cylinder fuel injection as a function of the position of the throttle and the time rate of change in the throttle position. Preferably, throttle position is measured with a potentiometer connected to the engine air intake throttle, and then filtered with a filter having a first order lag characteristic. Injection timing is advanced based upon a first predetermined schedule as a function of the measured throttle position. The difference between the measured and filtered throttle positions represents an indication of the time rate of change of throttle position and is employed to advance or retard timing in accordance with the second predetermined schedule, depending upon whether the difference is positive or negative, respectively.