Abstract: The automatic enrichment mechanism for an internal combustion engine is thermally-responsive and may also be centrifugally-responsive. The invention increases engine startability and minimizes stumbling and stalling of the engine during engine warmup. The thermally-responsive mechanism allows an additional reverse gas flow through the intake manifold to thereby increase the fuel discharged by the carburetor fuel nozzle. In several embodiments, the thermally-responsive mechanism, at low engine temperatures, causes a blocking or retaining member to keep an auxiliary cam member engaged with the cam follower of the valve assembly. As a result, the intake valve is partially unseated at low engine temperatures and a portion of the air/fuel mixture is fed back to the intake manifold. In these embodiments, when the engine temperature reaches a predetermined level, the thermally-responsive mechanism allows the auxiliary cam member to disengage from the cam follower in response to centrifugal force on the flyweights.

Abstract: A fuel injector nozzle comprising an inner member including an axially extending fuel passage adapted to communicate with a source of fuel under pressure and having an outlet end with a surface defining a valve seat, and an outer surface extending axially outwardly and converging to the valve seat, a valve member located in the fuel passage and movable axially thereof relative to the valve seat between open and closed positions, which valve member includes a valve head which is engageable with the valve seat when the valve member is in the closed position and spaced from the valve seat when the valve member is in the open position, and which includes an axially outwardly extending and converging surface, and an outer member surrounding the inner member and the valve head in spaced relation thereto and defining therebetween an air flow passage adapted to communicate with a source of air under pressure, which outer member includes an axially outwardly extending and converging surface located in spaced relation

Abstract: Disclosed herein is an exhaust system for a two-cycle internal combustion engine including a rotatable crankshaft, first and second cylinders firing 180.degree. apart, and first and second exhaust ports communicating with the first and second cylinders respectively, the exhaust system comprising a substantially Y-shaped hollow exhaust pipe having first, second and third branches each having an open end and each being substantially equal in length to the distance an acoustical wave will travel through the exhaust pipe during an interval over which the crankshaft rotates through substantially ten to twenty degrees of rotation at a predetermined engine speed, the open ends of the first and second branches being adapted to be coupled to the exhaust ports of the first and second cylinders respectively.

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: Disclosed herein is an apparatus which is adapted for controlling operation of an internal combustion engine operable selectively which is on gaseous fuel or liquid fuel, and which comprises a gaseous fuel supply line extending between the engine and a source of gaseous fuel, a liquid fuel supply line extending between the engine and a source of liquid fuel, and a control for controlling supply to the engine of the gaseous fuel and the liquid fuel, which control includes an operator controlled fuel selector switch movable between a gaseous fuel position and a liquid fuel position, which control is operable following prior engine operation with gaseous fuel and in response to movement of the fuel selector switch from the gaseous fuel position to the liquid fuel position for permitting liquid fuel flow through the liquid fuel supply line, for permitting continued gaseous fuel flow through the gaseous fuel supply line until initiation of liquid fuel combustion, and thereafter preventing further gaseous fuel flow

Abstract: Disclosed herein is a gaseous fuel and air supply system for an internal combustion engine, which system comprises an air-fuel mixing chamber, an air supply duct communicating with the mixing chamber and with the atmosphere and including a sensing tap, a flow control valve adapted to communicate with a source of pressurized gas, being operable between open and closed positions, and being biased toward the closed position, a fuel supply duct extending between the flow control valve and the mixing chamber and including a sensing tap, and an actuator communicating with the sensing tap in the air supply duct and with the sensing tap in the fuel supply duct for controlling operation of the flow control valve between the open and closed positions.

Abstract: The device for proportioning a gaseous fuel and air for combustion in an internal combustion engine includes a plate-like first member having a peripheral edge portion and a second member cooperating with the first member having a peripheral edge portion and a second member cooperating with the first member to define a mixing chamber having an outlet adapted to be connected in communication with the air intake of the engine carburetor. The second member also includes an annular portion having an arcuate first wall which is convex to and spaced from the peripheral edge portion of the first member to define an annular venturi having an inlet in communication with the atmosphere and an annular outlet in communication with the mixing chamber. A base member or second wall cooperates with the arcuate wall to form a substantially closed, annular plenum chamber into which a gaseous fuel, such as natural gas, is admitted when the engine is to be operated on the gaseous fuel.

Abstract: Disclosed herein is a spark advance control mechanism for an engine capable of being selectively operated on gaseous fuel and on liquid fuel.

Abstract: The device for proportioning a gaseous fuel and air for combustion in an internal combustion engine includes a plate-like first member having a peripheral edge portion and a second member cooperating with the first member to define a mixing chamber having an outlet adapted to be connected in communication with the air intake of the engine carburetor. The second member also includes an annular portion having an arcuate first wall which is convex to and spaced from the peripheral edge portion of the first member to define an annular venturi having an inlet in communication with the atmosphere and an annular outlet in communication with the mixing chamber. A base member or second wall cooperates with the arcuate wall to form a substantially closed, annular plenum chamber into which a gaseous fuel, such as natural gas, is admitted when the engine is to be operated on the gaseous fuel.

Abstract: Disclosed herein is an apparatus which is adapted for controlling operation of an internal combustion engine which is selectively operable using gaseous fuel or liquid fuel, and which comprises a gaseous fuel supply line extending between the engine and a source of gaseous fuel, a liquid fuel supply line extending between the engine and a source of liquid fuel, and a control for controlling supply to the engine of the gaseous fuel and the liquid fuel, which control includes an operator controlled fuel selector switch movable between a gaseous fuel position and a liquid fuel position, which control is operable following prior engine operation with gaseous fuel and in response to movement of the fuel selector switch from the gaseous fuel position to the liquid fuel position for permitting liquid fuel flow through the liquid fuel supply line, for permitting continued gaseous fuel flow through the gaseous fuel supply line until initiation of liquid fuel combustion, and thereafter preventing further gaseous fuel f

Abstract: The invention includes a combined clutch and brake mechanism for use in lawn mowers and other machines having a cutting means driven by a rotatably driven drive shaft. The combined clutch and brake mechanism includes a clutch member driven by the drive shaft. A brake member is spaced from the clutch member and is fixedly connected to the housing. A drive member is disposed between the clutch member and the brake member and is movable between a drive position wherein the drive member frictionally engages the clutch member and is rotatably driven by the clutch member and a brake position wherein the drive member frictionally engages the brake member and is restrained against movement. A linkage is provided for selectively moving the drive member between the drive position and the brake position.

Abstract: Disclosed herein is a chain saw including a drive shaft, a chain sprocket and a clutch including a drive member driven by the drive shaft and a driven member for rotating the chain sprocket in response to rotation of the drive shaft. One of the members is axially movable relative to the other between an engaged or driving position and a released position wherein they are disengaged from each other. The drive and driven members have intermeshing clutch teeth which coact to produce an axial force in a direction tending to separate the axially movable one of the members from the other. The members are releasably held in the driving position by a resilient element which is movable between a first position wherein it yieldably resists axial displacement of the axially movable one of the members and a second position which is spaced from the first position so as to permit movement of the axially movable one of the members to the released position.