Abstract: The invention relates to a portable handheld work apparatus having an internal combustion engine and an injection pump. The work apparatus includes an injection-pump block which is mounted on the housing of the work apparatus. The injection-pump block includes a feed pump for pumping fuel from a fuel tank mounted in the housing of the work apparatus and the injection pump for injecting fuel into the engine. An interface is provided between the block and the housing through which connecting lines are passed. Each line includes a connecting receptacle and a plug-in element at the interface. The plug-in elements jointly engage corresponding ones of the connecting receptacles when the injection-pump block is seated in the housing of the work apparatus. In this way, all connections of the connecting lines are made simultaneously when fixing the injection-pump block in position. A simplified installation of the injection-pump block in the housing of the work apparatus is achieved with the invention.

Abstract: A fuel supply system for a two cycle crankcase compression internal combustion engine embodying direct cylinder injection and carburetors for supplying a fuel air mixture to the crankcase chambers of the engine for high speed cooling. The direct fuel injectors supply the fuel at the low speed operation and a fixed amount of fuel at mid range and high speed, while the carburetor supplies only the mid range and high speed requirements of the engine in combination with the fuel injectors. Fuel is supplied first to the fuel bowls of the carburetors which have a vapor vent and then from the fuel bowls to the fuel injectors so as to avoid the necessity of a separate vapor separator for the fuel injectors.

Abstract: Disclosed herein is an internal combustion engine comprising first and second cylinders respectively including head ends and side walls, first and second pistons respectively reciprocably movable in the first and second cylinders between top dead center and bottom dead center positions, one of the first and second pistons being adjacent top dead center position when the other of the first and second pistons is adjacent bottom dead center position, a fuel supply venturi extending between the cylinders and including a throat, and a fuel injector located adjacent the head ends of the first and second cylinders, communicating with the throat, and including a valve movable between a closed position and an open position affording fuel flow into the throat.

Abstract: Disclosed herein is an internal combustion engine comprising a plurality of cylinders respectively including a head end, an exhaust port, and a pressure port located between the head end and the exhaust port, a like plurality of pistons respectively movable in the cylinders through respective compression strokes, a like plurality of fuel injectors respectively connected to the cylinders and operative to supply, from a fuel source to each of the cylinders, a metered quantity of fuel conveyed by compressed gas in response to fuel injector operation during the compression stroke of the associated cylinder, a storage tank for accumulating and storing compressed gas, a duct system including a selector value for selectively connecting the pressure ports to the storage tank only during the compression strokes of the associated cylinders, and a conduit connecting the storage tank to the fuel injectors for supplying the fuel injectors with compressed gas in response to fuel injector operation.

Abstract: A pump body which comprises three chambers, a first chamber communicating with the outer atmosphere and the air intake or the exhaust pipe, a second chamber communicating with the precompression casing of the engine, said second chamber being separated from the first chamber by a movable partition integral with a support held by a spring with a piston resting on the support and sliding axially in a channel when the movable partition displaces the support, and a third chamber having an opening communicating with the fuel intake line and an opening connected by a tube to a fuel injector opening into the drive cylinder in a substantially radial direction so as to spray the fuel over the flushing or sweeping currents.

Abstract: A four cycle internal combustion engine including a secondary intake system. The secondary intake system includes a pumping diaphragm actuated by pressure variation within the engine crankcase. The pumping diaphragm is in turn connected to the intake passage through a secondary intake passage to receive and expel air/fuel mixture toward the intake valving at appropriate intervals. A control valve control communication between the crankcase and the pumping diaphragm to restrict or allow actuation of the pumping diaphragm. An outlet also extends from the system to vent the crankcase at appropriate intervals.

Abstract: A crankchamber precompression type two-cycle internal combustion engine including at least one cylinder assembly, each cylinder assembly including a stepped cylinder constituted by a minor diameter cylinder portion and a major diameter cylinder portion, a stepped piston received in the stepped cylinder and constituted by a minor diameter piston portion and a major diameter piston portion adapted to be fitted in the minor diameter cylinder portion and the major diameter cylinder portion respectively, a crankchamber connected to the major diameter cylinder portion, a working chamber defined between the minor diameter cylinder portion and the minor diameter piston portion, and a sub-intake chamber defined between the major diameter cylinder portion and the minor diameter piston portion.

Abstract: A crankchamber precompression type two-cycle internal combustion engine including cylinder assemblies of an even number consists of at least one pair of cylinder assemblies having working cycles with 180.degree. phase difference, each cylinder assembly having a stepped cylinder constituted by a minor diameter cylinder portion and a major diameter cylinder portion, a stepped piston received in the stepped cylinder and constituted by a minor diameter piston portion and a major diameter piston portion, the minor diameter and major diameter piston portions being in sliding engagement with the minor diameter and the major diameter cylinder portions of the stepped cylinder respectively to provide an annular space serving as sub-intake chamber in the major diameter portions of the cylinders, the sub-intake chambers being connected to an auxiliary scavenging nozzle oriented toward a combustion chamber of the other associated cylinder.

Abstract: A fuel distribution system for an engine (10) having the fuel nozzles (74) located downstream from the air intake reed valves (52) to prevent the operation of the reed valves (52) from effecting the dual flow to the combustion chambers (42) through the transfer tubes (26). A manually operated pump (106) responds to an operator input to add or subtract fuel supplied to a flow divider (98) by a fuel valve (104) to provide a substantially immediate response from the engine to the operator input. A choke (160) receives an input from the engine to allow the mass air flow responsive fuel valve (104) to supply the flow divider (98) with an additional quantity of fuel during a starting operation.

Abstract: A two-cycle internal combustion engine includes a power cylinder, a drive piston being positioned therein. A first transfer duct extends between an auxiliary cylinder, which is supplied with carburetted air and the power cylinder and opens thereinto via a carburetted air inlet port provided on the side wall of the power cylinder or its combustion chamber. A pump crankcase, which is supplied with pure air, is connected to the power cylinder via a second transfer duct which opens thereinto via a scavenging inlet port on the side wall of the power cylinder. An exhaust port is provided on the side wall of the power cylinder. The ports are operatively arranged so that the scavenging port starts to open after the exhaust port and before the carburetted air inlet port.