Abstract: The invention relates to a membrane carburetor for an internal combustion engine in a portable handheld work apparatus such as a motor-driven chain saw. A throttle flap is arranged in the intake channel for the combustion air. The throttle flap is pivotally journalled downstream of a venturi section of the intake channel. A main nozzle for supplying fuel from a fuel-filled control chamber of the carburetor is provided in the region of the venturi section. The control chamber is delimited by a membrane which actuates a control valve controlling the fuel inflow into the control chamber. The main nozzle includes a check valve which includes a valve seat with a valve platelet assigned thereto. In order to avoid a dripping of the main nozzle even under unfavorable operating conditions, a sieve platelet is provided which effects an additional capillary sealing of the main nozzle during idle. The sieve platelet substantially completely covers the outlet cross section of the main nozzle downstream of the check valve.

Abstract: A diaphragm carburetor having a carburetor casing defining a mixing passage. A measuring chamber is disposed in the carburetor casing and is partitioned into a fuel chamber and a compensation chamber separated by a control diaphragm. The compensating chamber is closed to the surrounding atmosphere but is connected to a channel. An opening of the channel enters into a space between the air filter and a fuel inlet in the mixing passage. The channel is at least partially defined by a pipe extending through the carburetor casing. The pipe is adapted for assembly/disassembly from outside of the casing. The pipe is attached to a spacer for properly orienting and fixing the pipe relative to the casing during assembly.

Abstract: A carburetor having a fuel pump, a fuel metering diaphragm defining a fuel chamber on one side of the diaphragm and an air chamber on the opposite side of the diaphragm vented to the atmosphere, and a second diaphragm defining a first chamber on one side of the second diaphragm in communication with the carburetor fuel pump and a valve actuated by the second diaphragm to control the application of engine crankcase pressure pulses to the fuel metering diaphragm in response to the pressure at the carburetor fuel pump. The second diaphragm is yieldably biased to position the valve in a first position and upon cranking for initially starting the engine, pressure pulses from the engine crankcase are communicated to the air chamber of the fuel metering diaphragm. The pressure pulses from the engine crankcase act on the fuel metering diaphragm causing it to fluctuate and thereby increase the quantity of fuel mixed with the air flowing through the carburetor to facilitate staring the engine.

Abstract: A diaphragm carburetor system includes a diaphragm-controlled closed-loop control chamber for fuel communicating through a number of fuel conduits with an aspiration conduit for air. All of the fuel conduits extend separately from one another over their entire length in order to attain the least possible acceleration delay with simultaneously high efficiency. As a result, both a main channel and an idling conduit and each partial load conduit are supplied with fuel from the control chamber. Since an entry of air is prevented both into the partial load conduit or conduits and into the idling conduit, each conduit remains completely filled with fuel during the entire period of operation, so that upon sudden acceleration events, the fuel can emerge into the aspiration conduit of the diaphragm carburetor without delay.

Abstract: A carburetor having an idle nozzle and a main nozzle each with a fixed flow area and an idle speed single adjustment screw adjustable by the user. The idle and high speed fuel flows are controlled by the idle nozzle and the main nozzle, respectively. The user can adjust the engine speed only by adjustment of the idle speed adjustment screw which changes the position of the carburetor throttle valve to control the flow through the carburetor. This provides a more consistent fuel and air mixture to improve the performance of the engine and better control engine emissions by preventing the user from changing the fuel and air ratio to a mixture which is either too lean or too rich for the steady and low level exhaust emission operation of the engine.

Abstract: A vacuum actuated valve for a constant vacuum type carburetor is formed with a first guide hole, a jet needle engaging step portion and a jet needle insertion hole therein. A spring seat has an outer cylindrical portion in an upper portion thereof, and an inner cylindrical portion and a jet needle supporting cylindrical portion therein. The outer cylindrical portion of the spring seat is arranged on the outer circumference of a diaphragm plate. The jet needle supporting cylindrical portion is inserted within a first guide hole. A lower end of a vacuum actuated valve return spring engages with a spring seating flange of the spring seat. A flange portion of a jet needle is restricted by the jet needle engaging step portion and the jet needle supporting cylindrical portion.

Abstract: The present invention serves to facilitate atomization of fuel in a diaphragm type carburetor for all-purpose two-cycle engines. A check valve used to prevent back flow is installed in the fuel passage leading from a constant-fuel chamber to a main nozzle, and an air bleed passage is connected at a position on the downstream side of the check valve. The main nozzle is constructed by forming nozzle openings which face downstream with respect to the engine intake air flow. The nozzle openings are located in a tubular member which cuts across a central axial line of the venturi so that the tubular member bridges the neck of the venturi.

Abstract: A fuel delivery system for an internal combustion engine. The fuel delivery system includes a carburetor housing having an air passage with a throttle valve disposed therein. A choke lever is movably mounted to the carburetor housing for restricting air flow into the air passage. A fuel injection device is provided for injecting fuel into the air passage before the engine is started. Movement of the choke lever to an engaged position simultaneously opens the throttle valve, restricts air flow into the air passage and activates the fuel injection device to inject a predetermined volume of fuel into the air passage. The air-flow restriction and the predetermined volume of fuel are adjusted to compensate for changes in ambient temperature.

Abstract: A diaphragm carburetor for an internal combustion engine of a portable hand-held working tool has a housing with a control chamber. A suction channel extends through the housing and has a venturi section. An inlet valve is connected to the control chamber and supplies the control chamber with fuel. A main valve channel connects the control chamber to the venturi section of the suction channel. A check valve is positioned in the main valve channel adjacent to the control chamber and closes the main valve channel toward the control chamber. The main valve channel has a straight and elongate portion extending from the check valve into the venturi section and projecting into the suction channel.

Abstract: The invention is directed to a membrane carburetor which includes an intake channel having a throttle flap which is pivotally journalled. The carburetor also includes a control chamber from which fuel can be supplied to the intake channel. A valve is mounted in an ancillary channel and a corresponding adjustment of the throttle flap results in dependence upon the opening and closing position.

Abstract: A variable venturi carburetor, which is part of an intake system of an internal combustion engine, includes structural features which allow an air intake path of the carburetor to be shortened, and which allow the size of air chambers of the carburetor to be reduced. A piston valve is composed of a plate-shaped valve and a tubular portion. The plate-shaped valve is guided by a pair of grooves provide in sidewalls of the intake path. The tubular portion is attached to one side of the plate-shaped valve near a center of the side of the plate-shaped valve. The tubular portion has a rectangular or square cross-section. Each side of the rectangular cross section is shorter than the internal diameter of the intake path. A flange is attached to an upper end of the piston valve. The flange is of a reduced diameter and facilitates connection of the piston valve to a diaphragm.

Abstract: A fuel delivery system for an internal combustion engine. The fuel delivery system includes a carburetor housing having an air passage with a throttle valve disposed therein. The air passage has an inlet and an outlet. The outlet is in communication with the engine. Means are provided for simultaneously opening the throttle valve, restricting air flow into the air passage and injecting a predetermined volume of fuel into the air passage before the engine is started. Other means are provided for automatically adjusting the restriction of air flow and the predetermined volume of fuel to compensate for changes in ambient temperature.

Abstract: An internal vent system contains a pressure sensing orifice located in a carburetor main bore or an auxiliary bore. In one embodiment, this orifice is moved thereby sensing different combinations of total and static pressure of the moving gas stream in which it is located. In another embodiment, the orifice is fixed with a moveable restrictor which changes the gas flow velocity across the orifice and thus changes the pressure sensed by the orifice. The pressure in this orifice establishes the average reference pressure for a float bowl carburetor or a wet diaphragm carburetor, and hence establishes the fuel flow through the carburetor. This adjustable vent is effective in changing fuel delivery over a wide range of engine operating conditions, and is able to minimize the need for changing high speed jets or mid-range calibrations due to changing atmospheric conditions or other operating parameters. The vent movement can be manual or automatic.

Abstract: A fuel metering system comprises a throttle body 1 having an air passage 2, a throttle valve 6 mounted in the air passage, and at least one port 9-11, 13 opening into the air passage which is responsive to engine manifold vacuum to provide a negative pressure signal at a connector 12 or 14. The system also includes a repeater (FIG. 2) remote from the throttle body having a fuel inlet, a fuel outlet for delivery of fuel to the engine, and means for metering the delivery of fuel as a function of the negative pressure signal.

Abstract: A hand-guided, portable tool includes a housing and an internal combustion engine mounted in the housing. A fuel tank is mounted in the housing. The internal combustion engine has a carburetor with induction port for preparing a fuel/air mixture. An air filter is mounted in the housing. The air filter has a clean air side that is connected to the induction port. The internal combustion engine also has a control chamber with inlet valve. The control chamber is filled with fuel supplied thereto via the inlet valve from the fuel tank. The control chamber supplies fuel to the carburetor. The internal combustion engine has a compensation chamber delimited on one side by a control diaphragm that controls the inlet valve. The compensation line connects the compensation chamber to the clean air side of the air filter. The compensation line has a first connection section connected to the clean air side of the air filter and a second connection section connected to the compensation chamber.

Abstract: A down-drafting constant vacuum pressure type diaphragm carburettor includes a carburettor body with an induction passage, a throttle valve, a Venturi portion variable of open area. A vacuum actuated valve is arranged at upstream side of the throttle valve across the induction passage and extending in horizontal direction from one side to the other side, and controls an open area of a Venturi portion depending upon a vacuum pressure generated in the Venturi portion. A jet needle is mounted on the vacuum actuated valve. A fuel control system including a diaphragm arranged between a recessed portion of the carburettor body and a cover covering for defining a regulator chamber at the side of the recessed portion and an atmospheric pressure chamber at the side of the cover, and a valve seat. The diaphragm is arranged at lower side of a longitudinal axis of the jet needle.

Abstract: A diaphragm carburetor for an internal combustion engine has a housing and a control chamber positioned in the housing and having a fuel inlet valve. A control diaphragm is positioned in the control chamber. A Venturi channel extends through the housing. At least one throttle valve is positioned in the Venturi channel. An idle valve and a main valve open into the Venturi channel and are connected with an idle valve channel, respectively, a main valve channel to the control chamber. A fuel pump is positioned in the housing. A fuel channel connects the fuel pump and the fuel inlet valve of the control chamber. A control lever that is actuated by the control diaphragm for controlling the fuel inlet valve is provided. The fuel inlet valve has a valve seat and a valve member with a sealing member cooperating with the valve seat for opening and closing the fuel inlet valve. The sealing element has a flat end face. The valve member is connected to the control lever.

Abstract: An orifice assembly is detachably attached to a cover serving as a wall surface of an atmospheric chamber. The orifice assembly includes two inner and outer communication ports in a housing thereof. The two inner and outer communication ports are shut out by a partition wall through which an orifice having a small diameter and a communication hole having a diameter larger than that of said orifice, and a check valve is disposed in the communication hole to close the latter therewith. One of the two inner and outer communication ports is communicated with an atmospheric chamber and the other inner and outer communication ports is communicated with the atmosphere. When the pressure in the atmospheric chamber becomes higher than the atmospheric pressure, the communication hole is closed with the check valve, and when the pressure in the atmospheric chamber 48 is equal to or becomes lower than the atmospheric pressure, the communication hole is opened.

Abstract: A construction of a fuel supply pipe with a proximal end press-fit portion formed of metal and a metering tip portion formed of synthetic resin. The metering tip portion, formed with a fuel jet therein, is telescopically connected to the proximal end press-fit portion of the fuel supply pipe to provide a stable fuel supply in a rotary throttle valve type carburetor.

Abstract: To improve a carburetor including a main housing portion (12), in which a Venturi tube (2) and a throttling part (2a) are defined and which has an air intake side and an engine exit side, and a fuel pump (5) to the effect that, on the other hand a better starting procedure is provided and, on the other hand, the carburetor and, consequently, the engine are reliably prevented from getting flooded, it is suggested to supply fuel to the fuel pump (5) via a fuel intake (8) which is connected to the fuel tank (63) through a fuel line (64), and a fuel vapor supply (or vent) line (60) is provided which with its one end (61) is connected to the fuel intake feed channel (28) and with its other end (62) is connected to the fuel tank (63), and that in the route of the fuel vapor supply line (60) a check valve (66) is provided.

Abstract: The invention is directed to a carburetor for an internal combustion engine and includes an intake channel having a throttle flap mounted therein. Fuel passes from a fuel-filled control chamber via channels to main and idle nozzles through which the fuel enters the intake channel. The maximum permissible fuel quantity must be adjusted during a test run be means of an adjusting screw. This value can be changed by an operator. The maximum flow cross section for the fuel throughput is limited by at least one fixed throttle to which the main nozzle and the idle chamber are connected at the downstream end. In this way, strict exhaust-gas limit values are maintained. An adjustable throttle is provided with the aid of which the entire flow cross section can be reduced up to a pregiven minimum value. The carburetor described above is especially suitable for two-stroke engines of portable handheld work apparatus.

Abstract: An arrangement in an internal combustion engine comprises a membrane carbureter (10) having a fuel chamber (12) provided with a movable membrane (11) cooperating with a valve (17) for controlling the fuel supply to said fuel chamber. The air inlet of the carbureter is connected to a filter housing (31) provided with an air filter (32) for cleaning the inlet air, and a pressure chamber (13) is disposed adjacent said membrane and connected to said filter housing to control the fuel supply in relation to the pressure drop across said air filter (32). According to the invention, the membrane (11) is arranged in parallel with a wall (33) of the filter housing, and said wall is disposed adjacent to the pressure chamber (13) and provided with an opening (34) via which said pressure chamber communicates with the interior of said filter housing.

Abstract: A diaphragm-type carburetor has a high speed adjusting needle and a low speed/idle adjusting needle which are independently supplied with fuel from the metering chamber. The path for fuel to the low speed/idle needle has a valve which is controlled by the angular position of the throttle shaft such that when the throttle shutter is closed the valve is open whereas when the throttle shutter is open the valve is closed.

Abstract: In a carburetor for an internal combustion engine, the improvement embodying an air flow surface disposed strategically in a venturi or air flow passageway of the carburetor, the air flow surface providing enhanced air flow velocity characteristics over a region thereof relative to the free stream velocity over the air flow surface, and an orifice located adjacent to the air flow surface in the vicinity of the region of enhanced air flow velocity so as to provide a vacuum signal through the orifice which corresponds substantially proportionally to the air flow velocity through the venturi or air flow passageway, the vacuum signal being usable for improving fuel delivery characteristics to the venturi as well as for other purposes. Several methods for incorporating the present invention into existing carburetor constructions are likewise disclosed.

Abstract: The invention is directed to a membrane carburetor for an internal combustion engine such as a two-stroke engine having an intake for drawing the mixture in by suction. The membrane carburetor has a venturi section wherein the mixture is formed. A main nozzle opening opens forward of a throttle flap and an idle nozzle opening opens rearward of the throttle flap both viewed in flow direction. Both openings are connected via channels to a fuel-filled control chamber to which fuel flows via an inflow channel. An inlet valve is mounted in the inflow channel and has a valve body disposed opposite a valve seat fixed in the housing. The inlet valve is actuated in the opening direction via a control lever by a control membrane delimiting the control chamber.

Abstract: An engine for a portable working machine includes a carburetor having a fuel supply device which is to be operated by an intake pipe of a cylinder head provided with an intake valve and an exhaust valve, and a pulse pickup passage which is in fluid communication with the carburetor and which is connected to an inner wall of the intake pipe. The passage is provided at a connection portion between the intake pipe and the carburetor.

Abstract: A synthetic composite flexible diaphragm of a fabric of warp-knitted polyester fibers and an elastomeric polymer coating applied only to one side of the fabric and disposed in interstices between the fibers to provide when cured a barrier at least substantially impervious to liquid fuel.

Abstract: A diaphragm carburetor with both the main metering nozzle and an idle circuit supplied with liquid fuel from the same metering chamber and an accelerator and shut-off assembly in the idle circuit. The assembly has a valve which is open to supply fuel to the idle circuit when the throttle is in a closed idle position and closes off the supply of fuel from the metering chamber as the throttle is moved to its wide open position. Opening of the throttle also actuates a piston to supply additional fuel for accelerating an engine.

Abstract: An internal combustion engine with a diaphragm carburetor which provides additional fuel injection in all starting and environmental conditions. The carburetor is provided with a fuel recirculation line which communicates at one end with the fuel feed line of the carburetor, and which communicates at the other end with the fuel tank. The recirculation line is also provided with a choke for flow resistance.

Abstract: Method, system and apparatus for metering fuel to an internal combustion engine via a carburetor having a mixture conduit with a venturi therein. A main fuel nozzle supplies fuel to the venturi of the carburetor in response to the static pressure drop induced across an associated main fuel flow controlling restriction by the engine intake induced air flow through the carburetor mixture conduit. A pitot tube is disposed in the venturi with an opening facing upstream in a zone of maximum air flow through the carburetor venturi. A vent passageway system connects the pitot tube to a single closed air chamber cooperable with either a diaphragm or a float to regulate operation of an inlet valve controlling flow of fuel to a main fuel controlling restriction.

Abstract: The invention relates to a membrane carburetor having an air filter connected upstream of the intake channel. The combustion air passes through the air filter and into the intake channel of the carburetor and coacts with the fuel drawn into the intake channel to form a fuel/air-mixture which enters the combustion chamber of the engine communicating with the intake channel. The compensation chamber of the carburetor is connected exclusively to the clean-air side of the air filter in order to avoid an overenrichment of the mixture when the filter material of the air filter becomes contaminated. The membrane carburetor can be used on two-stroke engines for portable handheld tools such as motor chain saws, cutoff machines, brushcutters or the like.

Abstract: There is disclosed herein an arrangement for limiting the rotation of adjustment valves which control main and idle fuel paths in a diaphragm carburetor. The valves are disposed relatively close together and have caps that are configured to act as stoppers for each other so as to limit the maximum rotation of each valve.

Abstract: A mechanism for idling position adjustment of a diaphragm carburetor will be described. The carburetor includes an idling nozzle which receives a fuel/air emulsion from an emulsifying chamber under idling conditions. The emulsifying chamber receives fuel from a fuel chamber and air from an acceleration port opening into the mixing passage. Furthermore, the emulsifying chamber communicates via a flow control valve to a venting port opening into the mixing passage. The flow control valve is coupled to the shaft of the throttle valve via mechanical connection means so that the idle position of the throttle valve is varied in accordance with manual adjustments of the flow control valve. This allows to adjust the fuel/air ratios under idling conditions by means of a single adjustment member.

Abstract: The invention is directed to a control membrane of a carburetor including a carburetor chamber containing fuel. The control membrane defines a wall of this chamber and has a reinforcement portion in the center region thereof. This reinforcement portion transmits the membrane stroke to a controller lever. The control membrane provides for a simpler manufacture thereof and achieves a better functional reliability. The control membrane together with the reinforcement portion are configured as a one-piece component.

Abstract: A diaphragm type carburetor comprising a main body portion defining a venturi having an air intake side and an engine outlet side. The carburetor has a throttle shutter mounted within the venturi between the air intake side and the engine outlet side, and a metering chamber supplies fuel into the venturi via a main discharge port. The main discharge port opens into the venturi on the air intake side of the throttle shutter. A monitoring means (FIG. 3) is provided to monitor an engine parameter and an electrically controlled valve means is provided to adjust the fuel flow through the main discharge port into the venturi. The valve means is responsive to an electrical signal generated by the monitoring means in response to the engine parameter.

Abstract: The invention is an arrangement for controlling the air/fuel ratio A/F in a carburetor. The arrangement can be connected to a membrane or a float carburetor and controls the mixture ratio by influence on the differential pressure .DELTA.p between the fuel chamber (18) and the venturi (12). The subpressure from some part of the intake system (16) is passed through a magnetic valve (32) activated by pulses of a variable length. In order to equalize the whole or part of the subpressure there is an opening (33) with inlet from the atmosphere to the valve. By varying the pulse length a changeable subpressure is obtained which is connected in lieu of the regular atmospheric ventilation of the carburetor.

Abstract: An arrangement for limiting the temperature in a carburetor etc. of an engine prevents evaporation of fuel at a temporary stop in the operation of the engine. A receptacle (30) integrated with the carburetor contains a material (31), e.g. paraffin, with a melting point over the normal operating temperature. At a temperature above this melting point the material absorbs melting heat from the environment causing a limitation of the temperature. In this limited temperature the fuel evaporates much slower and a direct start with the remaining fuel after the operating stop is quite possible.

Abstract: The invention relates to a carburetor for an internal combustion engine and especially for a portable small engine. The carburetor includes a carburetor housing defining an intake pipe and a control chamber which communicates with the intake pipe via intake channels. A fuel-feed line which is closable by an inlet valve opens into the control chamber. The inlet valve includes a valve seat formed in the fuel-feed line and a valve body mounted on a positioning lever which is connected to a membrane defining a wall of the control chamber. The positioning lever can be pivotally actuated to open the inlet valve to admit fuel into the control chamber. An actuating lever is pivotally mounted on the carburetor housing and can be pivoted from a rest position to an active position whereat the actuating lever applies a force against the membrane to displace the latter and pivotally actuate the positioning lever to immediately open the inlet valve when starting the engine.

Abstract: In one embodiment of the present invention, a pulse fog generator powered by a resonant intermittent combustion device having a carburetor and a combustion antechamber, includes a starting air supply system for directing a flow of starting air into the antechamber, comprising an inlet/outlet ball check valve mounted over the discharge opening piston chamber within which a piston head is reciprocated by a connecting rod eccentrically mounted to an electric motor. A priming pump is mounted on the carburetor, and comprises a priming fuel chamber hydraulically communicating with the carburetor and a piston reciprocatable within the priming fuel chamber to draw fuel from a fuel tank into the priming fuel chamber and to discharge the fuel from the priming fuel chamber into the carburetor. In lieu of the reciprocatable piston, a resilient priming bulb and valve assembly can supply the priming fuel to the throat passage of the carburetor in another embodiment.

Abstract: In a charge forming apparatus comprising fuel supply means including an idling orifice and a low speed orifice for feeding the amount of fuel required during the period that an engine is idling or running at a low r.p.m. and a supplemental fuel passage for guiding the fuel to such orifices and an air feeding bypass for keeping the engine idling, the supplemental fuel passage is connected to a portion of the bypass upstream of a manually operable valve for regulating the flow rate of air by means of a connecting path. A negative pressure generated on the engine side rather than on a throttle valve makes negative the supplemental fuel passage and the bypass, but a negative pressure on the upstream side of a valve of the bypass varies in correspondence with the effective path area varied by the valve.

Abstract: An apparatus for reducing or eliminating the occurrence of vapor lock in two-cycle engines isolates the fuel pump from the heat radiating engine block in a two-cycle, air cooled engine spaces the fuel pump from the carburetor and injects the fuel directly against the carburetor inlet valve. Application of an additional cooling means including airflow and liquid fuel means, may be provided in order to convey heat away from the fuel pump and therefore maintain the fuel pump temperature below the point at which vaporation pressure exceeds the impulse pressure generated from the power head. The fuel pump is removed from the hot carburetor as part of the vapor lock prevention system.

Abstract: A carburetor comprising a main body portion defining a carburetor mixing passage having an air intake side and an engine outlet side, a fuel pump, a throttle shutter mounted within the carburetor mixing passage between the air intake side and the engine outlet side. The carburetor has a metering chamber for supplying fuel from the fuel pump into the carburetor mixing passage via a main discharge port, the main discharge port opens into the carburetor mixing passage on the air intake side of the throttle shutter. A starting fuel supply passage extends from the pressure side of the fuel pump to the carburetor mixing passage. A means is provided for selectively opening and closing the starting fuel supply passage such that when the throttle is in a partially opened position and the starting fuel supply passage is open, the fuel pump causes fuel to be injected through the starting fuel supply passage into the carburetor mixing passage.

Abstract: A vapor return primer for priming and regulating pressure in a carburetor is disclosed. The vapor return primer includes a housing having an inlet and an outlet. The inlet is coupled with the high pressure side of the carburetor. The outlet is coupled with a fuel tank. A resilient flexible membrane is coupled with the housing for moving fluid through the inlet and outlet to prime the carburetor. A pressure relief mechanism is coupled with the housing to provide one-way flow from the housing through the outlet to the fuel tank during priming. Also, the pressure refief mechanism regulates the carburetor pressure when the internal combustion engine is in a continuous running mode.

Abstract: A diaphragm-controlled carburetor which includes a diaphragm positioned in a chamber and dividing the chamber into wet and dry chamber sides. A valve is positioned in the wet chamber side, and is responsive to the diaphragm for feeding fuel to fuel jets and thence to a fuel/air passage. The dry chamber side is connected to receive pressure pulses from the engine crankcase through a three-position valve. The valve has orifices selectively interconnected by a rotatable valve disc for feeding pulses at first intensity to provide an enriched fuel/air mixture for starting, at a second lesser intensity to provide a less enriched fuel-air mixture for engine warm-up, and to block pressure pulses from the dry side of the control diaphragm.

Abstract: In the preferred embodiment of the present invention, a pulse fog generator powered by a resonant intermittent combustion device having a carburetor and a combustion antechamber, includes a starting air supply system for directing a flow of starting air into the antechamber, comprising an inlet/outlet check valve mounted over the discharge opening of a bellows that is reciprocated by a connecting rod eccentrically mounted to an electric motor. A priming pump is mounted on the carburetor, and comprises a priming fuel chamber hydraulically communicating with the carburetor and a piston reciprocatable within the priming fuel chamber to draw fuel from a fuel tank into the priming fuel chamber and to discharge the fuel from the priming fuel chamber into the carburetor.

Abstract: A carburetor comprises a main body portion defining a venturi having an air intake side and an engine outlet side, a throttle shutter mounted within the venturi between the air intake side and the engine outlet side, a fuel chamber for supplying fuel into the venturi via a main discharge port and at least one idle discharge port, the main discharge port opening into the venturi on the air intake side of the throttle shutter, a choke feed passage extending from the fuel chamber to the venturi, the choke feed passage opening into the venturi on the opposite side of the throttle shutter to the main discharge port, and means for selectively opening and closing the choke feed passage.

Abstract: A fuel primer for small internal combustion engines is disclosed. The fuel primer is associated with a metering chamber of a carburetor. The metering chamber includes an inlet port and an outlet port and communicates with both a fuel source and a venturi on the carburetor by conventional means. The primer includes a mechanism which communicates with the restricted inlet port to provide one way flow into the metering chamber. A second mechanism communicates with the unrestricted outlet port to provide one way flow from the metering chamber. A third mechanism associates the first and second one way mechanisms for pressurizing and depressurizing the flow through the primer so that fuel is drawn into the metering chamber from the fuel source.

Abstract: A carburetor arrangement changes the ratio of air and fuel in the air/fuel mixture for an internal combustion engine of a handheld motor-driven apparatus such as a chain saw, hedge trimmer or the like. The carburetor arrangement includes a membrane carburetor with a regulating membrane by means of which a valve needle is lifted from a valve seat against the force of a spring. The valve needle and valve seat conjointly define a valve for admitting fuel into a chamber of the carburetor. A positioning member is mounted with respect to the regulating membrane and is actuable in dependence upon the rotational speed of the engine. The actuation occurs such that the valve needle is additionally displaced a further incremental amount in response to a predetermined rotational speed of the engine thereby enriching the air/fuel mixture by an additional amount.

Abstract: A diaphragm carburetor with a fuel metering chamber designed for easy restart when hot which includes a separate escape chamber connected to the metering chamber having a second diaphragm controlled exhaust valve. The second diaphragm is subject to positive crankcase pressure during engine operation to maintain the exhaust valve closed. When the engine is stopped, the exhaust valve is opened by a spring and fuel in the metering chamber will move into the escape chamber and out of the carburetor rather than be forced into the fuel mixing passage and venturi of the carburetor. A porous absorbent material is positioned to receive the fuel leaving the open exhaust valve and to retain it until it vaporizes and dissipates through openings in the retainer atmosphere. The exhaust valve may be manually operated as an option.

Abstract: A diaphragm carburetor with a fuel metering chamber designed for easy restart when hot which includes a separate escape chamber connected to the metering chamber having a second diaphragm controlled exhaust valve. The second diaphragm is subject to positive crankcase pressure during engine operation to maintain the exhaust valve closed. When the engine is stopped, the exhaust valve is opened by a spring and fuel in the metering chamber will move into the escape chamber and out of the carburetor rather than be forced into the fuel mixing passage and venturi of the carburetor.