Abstract: Crankcase scavenged internal combustion engine (1) of two-stroke type, intended for a working tool, preferably a chain saw or a trimmer, and provided with a light-weight and compact muffler (2). The engine is arranged with a particularly high crankcase compression created in that at least one filling (3, 4, 5, 6) is placed into the compression area (7) under the engine piston (8) in form of a filled balance (3) and/or a piston filling (4) and/or a piston washer (5) and/or a stationary filling (6), at the same time as the engine is provided with an especially strong throttling created in the engine's exhaust side, i.e. in its exhaust port (9) and/or in a possible exhaust duct (10) and/or in the muffler (2).

Abstract: Disclosed is a two cycle engine designed and configured to replace conventional four cycle engines in a modern day automobile without any alternations, while steel accepting all of the accessories (i.e. air conditioning, power steering, alternators), without any modifications to the external structure of the engine block. This engine composites casting carbon--carbon cylinders, having carbon--carbon pistons located therein, into an aluminum block so all of the current external dimensions are maintained for manufacturing purposes.

Abstract: A two cycle, crankcase compression, diesel engine having a high specific output. This is achieved by using an appropriately sized and located precombustion chamber into which the fuel is injected. The porting and direction of crankshaft rotation insure against compression and combustion leakage.

Abstract: A feed back control system for a direct injected, two cycle engine having a catalytic exhaust. The injection control is modified if the catalyst overheats to control its temperature.

Abstract: The modification of the exhaust valve of a two cycle diesel engine in order to increase the amount of the valve stem travel and hence larger annular opening, without changing the total time period or degrees of crank shaft rotation during which time the exhaust valve is open and permits the combusted fuel air mixture to exhaust is disclosed. In cooperation with the improved valve opening, the intake port for the intake air is lowered and lengthened to therefore permit a longer power stroke, and the input of more air which, when combined with the improved scavenging, increases the amount of oxygen available for combustion. The increase in the opening of the valve is achieved by shortening one of the two arms of the rocker arm which engages the valve stem, the arm shortened being the arm which is activated by the push rod. This results in a lengthening of the stroke of the valve stem and the valve which translates into a larger annular opening for exhaust. In addition, the exhaust sector of the 180.degree.

Abstract: An internal combustion engine has a fuel and air mixing device which utilizes an open bore venturi to draw fuel from the device and deliver a rich fuel and air mixture to a compressor driven by the engine for direct injection of the rich fuel and air mixture into the engine. An engine air throttle body uses an engine throttle linkage and valve to control air flow into the engine crankcase and provides a positive air pressure signal, especially at small throttle openings, to assist the metering of fuel within the fuel and air metering device. The positive air pressure signal is preferably provided by a small port in the engine air throttle body slightly downstream of the throttle valve when closed and is communicated with the fuel and air metering device to cause additional fuel to be delivered from the device.

Abstract: A reverse rotation control system for a two-cycle engine of a motor vehicle which can be implemented inexpensively while preventing exhaust gas from degradation. The system includes a variety of sensors for generating signals corresponding to engine operation states, and an ignition control unit (10A) for generating an ignition signal (P) on the basis of the various signals. The sensors include a rotation sensor (6) for generating a rotation signal (SG) indicating engine rotation number (Re) and a reverse rotation switch (23) for generating a reverse rotation command signal (RW).

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-cycle internal combustion engine provided with at least one fuel injection nozzle, wherein the fuel injection nozzle is provided with a heating element for heating the fuel so as to cause the fuel to undergo a phase change before the fuel is injected from the fuel injection nozzle. A fuel control circuit for controlling the heating element is attached to the engine so that an AC electromotive force generated at a generator portion of an ignition device is input therein and, based on such electromotive force, the heating element is controlled. All of the ignition device, the fuel controlling circuit and the generator portion are formed into a single integrated body which functions as an ignition/fuel controlling device.

Abstract: An improved feedback control system and method for internal combustion engines that permits extremely accurate feedback control. This is done by utilizing a sensor device that is interrelated with the combustion chambers of the engine so that it only samples the gases from the engine at a time after the exhaust port has opened and before any fresh air charge enters the combustion chamber. By doing this, it is possible to ensure that only combustion product reach the sensor and the sensor chamber will have a time to purge itself of the combustion products from one cylinder before another sampling takes place. This is described in conjunction with both two and four-cycle engines.

Abstract: The efficiency of a vehicle having a body and a reciprocating piston four-stroke internal combustion engine is increased substantially by greatly reducing the size of the engine relative to the weight of the body. The great reduction in engine size relative to the weight of the body causes the engine to operate in a much more efficient range during almost all of the time of its operation. Peak power needs are satisfied by turbocharging and varying the compression ratio.

Abstract: A system for reversing the direction of a two-stroke, internal combustion engine provided with a spark ignition system, the engine having at least one cylinder and a piston reciprocating therein and connected to drive a rotary crankshaft, the system comprising: a manually operable inverse command button; trigger means located proximate a rotary member driven by the crankshaft, a cooperating member carried on the rotary member and cooperating with the trigger means as the rotary member rotates to generate a train of pulses; means detecting the direction of rotation of the crankshaft and generating a direction signal indicative of direction of rotation; a microprocessor control unit receiving the train of pulses, the direction signal and an output from the inverse command button and connected to control the spark ignition system, the microprocessor monitoring the speed and direction of rotation of the rotary member on the basis of the train of pulses and the direction signal, the microprocessor operable when th

Abstract: A feedback control system for controlling the fuel/air ratio of an engine. The system employs a fuel/air ratio or combustion condition sensor and includes a checking system for checking if the sensor is providing reliable data. This is determined by determining whether the output of the sensor changes when an adjustment in the amount of fuel supplied is made. If the sensor check indicates unreliable signals, then the system operates on an open control.

Abstract: An internal combustion engine in which the piston (10) rocks about a pivot point (60) with the piston (10) being connected adjacent the end remote from the pivot point (60) to a connecting rod (12) to drive a crankshaft. The piston (10) has a first arcuate sealing surface (41) and a second arcuate sealing surface (42) which is offset radially from the first sealing surface (41) with the first and second sealing surfaces (41, 42) being connected by a floor (44). The first arcuate sealing surface (41) seals against a correspondingly arcuate wall (51) of the combustion chamber (20) and the second arcuate sealing surface (42), which forms one wall of the combustion chamber (20), seals against a wall (52) of a boost chamber (53). The engine can be compression ignition or spark ignition and can be of the two-stroke cycle or four-stroke cycle.

Abstract: An internal combustion engine includes: a cylinder block having a connecting surface formed at a lower portion thereof and a skirt portion extending outwardly from the connecting surface; a crankcase having a connecting surface for contacting the connecting surface of the cylinder block and a bore for inserting the skirt portion therewithin; and, a gasket interposed between the connecting surfaces of the crankcase and the connecting surface of the cylinder block when assembled such that the gasket has a bore formed at the central portion thereof. A pair of detent portions are formed at the outer periphery of the skirt portion with each of the detent portion being different in shape from each other. A pair of recess portions, corresponding to the detent portions, are formed at each of the bores of the crankcase and the gasket.

Abstract: The modification of the exhaust valve of a two cycle diesel engine in order to increase the amount of the valve stem travel and hence larger annular opening, without changing the total time period or degrees of crank shaft rotation during which time the exhaust valve is open and permits the combusted fuel air mixture to exhaust is disclosed. In cooperation with the improved valve opening, the intake port for the intake air is lowered and lengthened to therefore permit a longer power stroke, and the input of more air which, when combined with the improved scavenging, increases the amount of oxygen available for combustion. The increase in the opening of the valve is achieved by shortening one of the two arms of the rocker arm which engages the valve stem, the arm shortened being the arm which is activated by the push rod. This results in a lengthening of the stroke of the valve stem and the valve which translates into a larger annular opening for exhaust. In addition, the exhaust sector of the 180.degree.

Abstract: An engine/generator set, especially for use in driving a hybrid motor vehicle, in which an internal combustion engine is equipped with free flying pistons. The internal combustion engine operates in a two-stroke cycle with asymmetrical electrically controlled gas exchange with an exhaust gas turbine driving a turbocompressor. The power excess is fed back via a synchronous alternating current machine to the generator so that the vehicle is driven with high efficiency with an apparatus of reduced volume and weight per unit output.

Abstract: A number of embodiments of outboard motors embodying pressure scavenged 2-cycle internal combustion engines. In each embodiment, a plenum chamber serves the scavenge passages of the engine and the pressure relief for a scavenge pump is provided by a pressure relief valve in the plenum chamber so as to reduce the opening and closing of the pressure relief valve due to pulsations caused by the engine operation. In one embodiment, the pressure is relieved by discharging the air to the exhaust system for silencing and also for cooling the exhaust gases. In other embodiments, the air for pressure relief is discharged to the atmosphere.

Abstract: A balanced motor two-stroke cycle engine having a linear drive includes a sealed gearcase secured to a cylinder housing having a plurality of concentric cylinders. The sealed gearcase includes a fixed ring gear, a pinion gear whose diameter is equal to the radius of the ring gear, a hub on which a piston rod is journaled for rotation, and two sets of counterweights. The piston rod moves in a linear fashion as the pinion gear rotates inside the fixed ring gear. The piston rod extends into the innermost cylinder, and a piston secured to the piston rod reciprocates linearly in the innermost cylinder. Different embodiments of exhaust valve structure are illustrated in different embodiments, and an external combustion chamber embodiment is also illustrated.

Abstract: A combustion chamber assembly for a two-stroke internal combustion engine has, in the upper dead point position of the piston, a space defined between the piston bottom and the cylinder head which is of the shape of a frustum of a right-circular cone or the shape of a right-circular cylinder. Surfaces of the piston bottom and the cylinder head extend tangentially to the wall of the space at 180.degree. offset from one another and are juxtaposed with surfaces of the cylinder head and piston bottom, respectively, defining narrow gaps squeezing fluid flow into this space tangentially form opposite directions to induce a vortex in the space in a single sense. The fuel injector opens axially into this space for autogenous ignition or self-firing or a spark plug extends axially into this space for external ignition.

Abstract: An improved internal combustion engine, particularly of the compression ignition, two cycle, aircraft type employing sleeve valves and a modular cylinder and removable cylinder head and retainer. The engine is turbocharged with the turbocharger separated into the compressor on one side of a V shaped cylinder array and the drive turbine on the opposite side. The exhaust is discharged through the center of the power output shaft making this engine particularly suited for pusher aircraft applications.

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 reversing internal combustion engine has an ignition system controlled by a microprocessor which samples the magneto voltage output in order to make decisions concerning spark/timing. By suppressing the spark to allow the engine to slow down, and reapplying the spark at a suitable advance, reversal of the engine is effected from forward to reverse or reverse to forward.

Abstract: In the embodiments described in the specification, a mixture-compressing internal combustion engine has intake and exhaust valve opening and closing times arranged to permit scavenging of the combustion chamber with fresh gas and a valve control is provided to advance the intake valve closing time as a function of engine load in order to increase the compression stroke under partial load conditions. The intake valve opening time and the exhaust valve opening and closing time may also be changed in accordance with the load.

Abstract: A bearing for receiving a crankshaft positioned in a crankcase of an inboard/outboard internal combustion engine which includes a seal member for sealing the inside of the bearing so as to prevent corrosion of the bearing. Preferably, the crankcase includes a plurality of crank chambers to accommodate a crankshaft rotatably received by a plurality of bearings, each of which includes a seal member.

Abstract: An engine, operating in accordance with the two-stroke cycle, is characterized in that the intake and exhaust timing elements are valves (7, 9). The control device for the valves is responsive to a parameter such as the speed of rotation of the engine, the comsumption of fuel, the value of a super-charging pressure, or the difference between the intake and the exhaust pressure. The control device is used for varying the angular position in the cycle of operation of the opening and the closure of the valves (7, 9) to obtain the introduction of a sufficient quantity of fresh air in the work chamber in the least favorable condition of operation, in particular by opening the intake during a period of increase in volume of the chamber.

Abstract: A crankshaft support structure comprises a crankshaft, a crankcase for supporting the crankshaft, a lubricant-sealed bearing interposed between the crankshaft and the crankcase. This structure enables the amount of a lubricant in combustion gas to be reduced and the structure of an engine to be simplified by avoiding the provision of a oil passage for suppling the bearing with a lubricant.

Abstract: An internal combustion engine provided with an air cleaner and a muffler respectively on both sides of the crankshaft of the engine body and with a fuel tank below them wherein the air cleaner and the muffler are formed to be vertically extended respectively at the lower ends thereof along both sides of the engine body, the fuel tank is formed to be substantially like T made integrally of a barrel part and a head part inflated out on both sides in front of the barrel part, the barrel part is fitted in a space made by the air cleaner and the muffler below the engine body and both side parts of the head are arranged respectively in front of the lower parts of the air cleaner and the muffler.

Abstract: An engine control system is disclosed for reducing the hydrocarbon content in exhaust gas from a crankcase scavenged, two-stroke engine in the operating range near idle, with light operator induced engine loading. As operator demand for engine output power is increased, the control system increases the fuel per cylinder delivered to the engine, while restricting the supplied mass of air per cylinder to a value less than or equal to that flowing at unloaded engine idle.

Abstract: A two-stroke internal combustion engine is provided including an engine block, a combustion chamber defined in the engine block and adapted to have a piston reciprocate therein along an axis between a top dead center position and a bottom dead center position, and to have air and fuel combusted therein, thereby causing production of an exhaust gas and at least partially causing the piston to reciprocate, the internal combustion engine further comprising an exhaust port communicating with the combustion chamber and adapted to conduct the exhaust gas away from the combustion chamber, a sensor chamber at least partially defined in the engine block, a passage extending from the sensor chamber to the combustion chamber at a location axially between the exhaust port and the top dead center position, valve structure, operable in the passage for allowing flow of exhaust gas from the combustion chamber to the sensor chamber, and for preventing flow of non-combusted air and fuel from the combustion chamber to the senso

Abstract: In a two-cycle internal combustion engine (10), the piston (20) has an outer peripheral oval shape (58) with a minor axis (62) offset from the centerline (54) of the wrist pin (26) towards a line (56) through the intake and exhaust ports (16 and 18). The outer peripheral shape of the piston also has increasing ovality, from at least the wrist pin (26) upwardly to at least the piston rings (22, 24).

Abstract: The present invention relates to an internal combustion engine cylinder assembly comprising a cylinder having substantially vertically disposed interior walls defining a firing chamber therein; piston means housed within the firing chamber and adapted for vertical reciprocation within the firing chamber; gas inlet channels in the lower portion of the firing chamber; a crankcase housing having a gas compression chamber disposed therein; valve means adapted for passing air into the gas compression chamber upon the depressuring thereof; cylinder closure means positioned at the upper end of the cylinder defining the upper end of the firing chamber and being provided with exhaust gas valve means, adapted for cyclic opening and closing to alternatively permit the removal of exhaust gases from the firing chamber and the pressuring of fresh fuel/air mixtures in the firing chamber; fuel introduction means for introducing fuel into the upper portion of the firing chamber; fuel ignition means for igniting a compressed f

Abstract: Several embodiments of outboard motor fuel feed systems wherein a position responsive valve is interposed between a remotely positioned fuel tank and the engine charge former for precluding the inadvertant flow of fuel to the charge former when the outboard motor is tilted up. In each embodiment, the valve is a gravity responsive valve and in another embodiment a pressure responsive valve member is provided for ensuring fuel flow when the outboard motor is again tilted down to its normal running position.

Abstract: An internal combustion engine cylinder assembly comprising a first elongated cylinder having substantially vertically disposed interior walls defining an elongated firing chamber therein; first piston means housed within the firing chamber and adapted for vertical reciprocation within the firing chamber; gas inlet channels means in the lower portion of the firing chamber; a crankcase housing having a gas compression chamber disposed therein; valve means adapted to permit fresh fuel/air mixtures to be charged into the gas compression chamber upon the depressuring of the chamber; second cylinder means positioned at the upper end of the first cylinder and having an exhaust chamber therein and a second piston means disposed within the exhaust chamber and adapted for vertical reciprocation therein, the exhaust chamber communicating with the upper end of the firing chamber; the second cylinder means being provided in the lower portion thereof with at least one exhaust gas port adapted for cyclic opening and closing

Abstract: An internal combustion engine cylinder assembly comprising an elongated cylinder having substantially vertically disposed interior walls defining an elongated firing chamber therein; piston means housed within the firing chamber and adapted for vertical reciprocation within the firing chamber; gas inlet channels in the lower portion of the firing chamber; a crankcase housing having a gas compression chamber disposed therein; a reed valve means pivotally secured to the inner walls of the gas compression chamber and adapted for passing fuel/air mixtures into the gas compression chamber upon the depressuring thereof; a cylinder closure means positioned at the upper end of the cylinder defining the upper end of the firing chamber and being provided with exhaust gas valve means, adapted for cyclic opening and closing to alternatively permit the removal of exhaust gases from the firing chamber and the pressuring to the fresh fuel/air mixtures in the firing chamber; fuel ignition means for igniting a compressed fuel

Abstract: An illustrative embodiment of the invention provides a four cycle internal combustion engine that produces one power stroke for each full rotation of the crankshaft. Direct fuel and oxidizer injection into the cylinder permits engine speed and power to be controlled by varying the duration of the intake stroke. This duration is controlled, moreover, by moving the distributor housing in relation to piston top dead center position.

Abstract: There is described a charging and distributing device for a piston engine, the device including a variable displacement rotary compressor delivering through one of its shafts to a coaxial rotating distribution tube (1,25), the tube being formed with ports (4,29) which sequentially coincide with inlets (7,27) to the respective cylinders of the engine. A control system (14) to regulate the displacement of the compressor is disclosed, and the use of eccentrically weighted rotary pistons (10,12) and/or distribution tube to balance the engine as a whole is envisaged.

Abstract: Several embodiments of fuel injection controls for two-cycle crankcase compression internal combustion engines. In each embodiment, the fuel injection is controlled by measuring the amount of air inducted through measurement of the pressure generated in the crankcase. In each embodiment, abnormal pressure variations in the crankcase not due to the amount of air inducted are eliminated by measuring the pressures at predetermined crankshaft angles. In some embodiments, this is done through the use of a valving arrangement and in other embodiments, this is done electronically.

Abstract: A 2-stroke engine having a combustion chamber and a scavenge port which is open to the combustion chamber. When the engine is operating under a light load in which a large amount of unburned components, incompletely burned components and oxygen remains in the combustion chamber, fresh air is fed into the combustion chamber from the scavenge port at a low speed so that the fresh air does not disturb the residual gas in the combustion chamber. As a result of this, oxidation of the unburned components and the incompletely burned components continues without interruption during the expansion stroke and the compression stroke and causes self-ignition of the residual gas at the end of the compression stroke. The self-ignited residual gas causes ignition of the fuel injected into the combustion chamber from a fuel injector.

Abstract: A two-cycle, gas-powered engine which is capable of operating over a wide range of loads including those (e.g. idle speed) which have previously caused misfirings in known engines of this type. A specially constructed head and piston assembly and a governor-controlled fuel system are incorporated into an otherwise typical two-cycle engine to convert the engine into a stratified charge engine. The head and piston assembly is constructed to provide an ovate-domed, flat-bottomed combustion chamber therebetween when the piston is in a top dead center position in the cylinder. This combustion chamber allows fuel injected in the top of the combustion chamber to mix with air being compressed by the piston to provide a rich stratified charge around the ignition means (e.g. spark plugs) which are also positioned near the top of the chamber. This charge is always rich enough to support rapid ignition and to quickly spread burning to the weaker, exhaust-contaminated mixture present in the lower combustion chamber.

Abstract: A two-stroke engine includes an intake-and-scavenge valve in the cylinder head together with a fuel injection system, a recirculating type pressure lubricating system, and a blower or turbo charger assisting in charging the cylinder with air and also assisting in scavenging the exhaust gases . The piston head is domed with one side curving downwardly towards the exhaust port formed through the wall of the cylinder above the bottom dead center position of the piston head. The exhaust port slopes outwardly and downwardly following generally the slope of the piston to facilitate the flow of exhaust gases therethrough assisted by the scavenging air entering through the inlet-and-scavenger valve. The valve is operated by a cam mounted on a cam shaft upon the cylinder head which in turn is operatively connected to the crankshaft. The width of the cam lobe is such that the opening, closing and duration of opening of the valve is controlled with the valve being opened approximately 140.degree.

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

Abstract: A 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: An aluminium 2-stroke engine cylinder and the crank case assembly is provided, in which a cylinder flange rests in sealing manner over its entire area upon a corresponding counter-surface of the crank case and a deformable packing lies between the sealing surfaces and in which the flange is tightened to the crank case by means of screws. The mutually opposite sealing surfaces of flange and crank case are slightly inclined in relation to one another in such a way that the distance between the sealing surfaces is greater radially inwards than radially outwards.

Abstract: An improved two-cycle Diesel internal combustion engine is provided, whereby the intake and exhaust port passages are modified to provide greater circulation of the combustible fluids and air during the intake and exhaust cycles of the Diesel engine, respectively. The intake passages are so located in each piston and each cylinder to provide communication thereinbetween during the intake cycle with the piston at the bottom of its stroke which effects the exhaust cycle simultaneously substantially similar to a normal two-cycle operation. The intake passages in each cylinder communicate with intake passages in each piston which are connected to an intake flume port located epicentrically in the upper portions of each piston. The movement of the combustible fluids and the evacuation air is directed from the intake flume port and deflected off a conical protrusion in the upper surface of the cylinder, in order to promote circulation of the combustible fluids and the evacuation air, respectively.

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: A two-cycle air-cooled engine has a carburetor with a throttle valve operated by a manual control member. A heat sensitive valve mounted on the engine cylinder head closes to cut off a supplementary air supply to the induction passageway and thereby richen the air-fuel mixture to prevent seizure upon overheating. When the manual control member is in position corresponding to idling of the engine, the member actuates means which introduce additional air into the induction passageway leading to the engine, to lean the air-fuel mixture.

Abstract: In a non-load operation of a multi-cylinder internal combustion engine, both suction flow of newly supplied air-fuel mixture to be introduced in a first combustion chamber and exhaust flow of combustion gas to be exhausted from the first combustion chamber or only the exhaust flow is throttled to carry out compression ignition combustion in the first combustion chamber, while suction flow of newly supplied air-fuel mixture to be introduced into a second combustion chamber is blocked to stop combustion in the second combustion chamber to increase a gas feed rate in the first chamber, to thereby cause a kind of run-on phenomenon in the engine in non-load condition.

Abstract: A port in the cylinder wall of a two-stroke cycle engine is connected by a passage and a restricted orifice with the idle reservoir of a diaphragm type carburetor. The idle reservoir is connected through an adjustable idle mixture valve with the metering chamber. The passage from the engine port is connected by a vent passage with the venturi of the carburetor. The dry side of the metering diaphragm is vented by a restricted opening and is connected with the dry side of a crankcase pressure operated fuel pump through a passageway having therein a check valve and a valve which is open when the choke valve is closed. This connection allows pressure pulses from the crankcase to influence fuel flow so that the desired fuel flow is obtained under more than one engine operating condition. In addition fuel is introduced directly into the crankcase at idle speeds instead of into the throttle bore giving more stable idle condition.