Abstract: In a multipurpose engine with a reduced or limited displacement adapted for use in a portable work machine or the like, the engine includes a detecting element of a gas sensor for controlling an air-fuel ratio. Damage or degradation of the detecting element due to vibration from the engine is reduced or eliminated. To achieve this, a supporting device having a vibration-damping-function is provided for supporting the gas sensor or the gas sensor unit containing the gas sensor. The supporting device permits the gas sensor or the gas sensor unit to move by an amount equal to or less than a predetermined extent of movement of the engine, so that the transmission of vibration from the engine directly to the gas sensor is reduced or eliminated.

Abstract: A device that corrects with ease and high precision any deviation of the fuel flow rate due to variation in the constituent components of a carburetor, and to improve the exhaust condition and operability of an engine. A carburetor in which the delivery channel 23 and the suction channel 20 of a fuel pump 15 are connected with the aid of an escape channel 27, and in which a portion of the delivery fuel is allowed to escape to the suction side in order to prevent pressure exerted on the fuel valve 10 by the fuel delivered to the constant fuel chamber 5 from the fuel pump 15, which operates by pressure pulses, from reaching or exceeding a specified level, wherein the escape channel 27 is equipped with a manual control valve 29 for steplessly adjusting the surface area thereof.

Abstract: A starting apparatus of a diaphragm-type carburetor, a starting pump disposed at a convenient and accessible location which is separate from a carburetor main body, and air is prevented from being mixed into fuel, in such a structure constructed as a suction-type starting pump. A suction passage extends from a fuel metering chamber and extends beyond an outer portion of the carburetor main body. A starting pump conveniently disposed is separate from the carburetor, and an inlet check valve of the starting pump is disposed in the carburetor main body so as to reduce a volumetric capacity of a section extending to the inlet check valve from the fuel metering chamber, thereby preventing the air from remaining within the suction passage.

Abstract: In a multipurpose engine with a reduced or limited displacement adapted for use in a portable work machine or the like, the engine includes a detecting element of a gas sensor for controlling an air-fuel ratio. Damage or degradation of the detecting element due to vibration from the engine is reduced or eliminated. To achieve this, a supporting device having a vibration-damping-function is provided for supporting the gas sensor or the gas sensor unit containing the gas sensor. The supporting device permits the gas sensor or the gas sensor unit to move by an amount equal to or less than a predetermined extent of movement of the engine, so that the transmission of vibration from the engine directly to the gas sensor is reduced or eliminated.

Abstract: The present invention provides a carburetor that can be adapted to a variety of engines with different positional relationships between the location for feeding the air/fuel mixture and the location for feeding scavenging air. The carburetor a carburetor main body (22) with an air intake passage (24) forming a portion of the air/fuel mixture passage (23) and is provided with an air passage (33) that forms a portion of an air channel (32) for scavenging air. The air passage (33) is positioned parallel to an air intake passage (24), and the front end thereof is positioned further to the base end side than to the engine-side front end face of the carburetor main body (22), enhancing the degree of freedom for placing the conduit pipe (34) for connecting the air passage (33) to the scavenging air feed port (9). Also, the throttle valve (26) and the air valve (35) are butterfly valves with mutually parallel valve stems, and the interlocking mechanism thereof has a simple configuration.

Abstract: An accelerator for a carburetor that is linked to a throttle valve and allows a piston-type accelerator pump to be operated in a simple configuration that dispenses with a link mechanism and does not greatly enlarge the carburetor. The lower surface of a throttle valve lever (10) is provided with a cam (33) that has a circular shape centered about a throttle valve stem (8) and is configured such that the cam surface (33A) thereof faces a carburetor main body (1). An accelerator pump (25) is placed parallel to the throttle valve stem (8) and the upper end of a piston rod (28) thereof is brought into contact with the cam surface (33A). The cam (33) pushes the piston rod (28) down as the throttle valve lever (10) swings in the opening direction of the throttle valve, and the acceleration fuel in the pump chamber (29) is delivered and supplied to the suction channel (2).

Abstract: An air fuel ratio control apparatus readily satisfies an emission requirement and is particularly preferable for small-displacement engines. The air fuel ratio control apparatus for an engine includes a fuel control member disposed in a fuel passage delivering fuel from a fuel metering chamber of a carburetor supplying the fuel to a suction passage of a comparatively small engine such as a general purpose engine, a working machine engine and the like, a combustion gas sensor disposed in an exhaust pipe in the engine, and an electronic control unit. The control unit actuates the fuel control member in response to a concentration of a combustion gas component in an exhaust gas detected by the combustion gas sensor so as to control a fuel flow rate.

Abstract: An interlocking lever having first and second cam faces is mounted on a throttle valve stem, and a throttle valve is arbitrarily opened to perform start-up in a state in which the first cam face makes contact with the choke valve lever and the interlocking lever is stopped during low-temperature start-up with the choke valve closed. After the choke valve has been returned to the fully open position, the throttle valve alone is opened with a small degree of opening to perform low-load operation; and in the mid- and high-load region, the interlocking lever integrally turns with the throttle valve, the second cam face pushes the air valve lever, and the throttle valve and air valve are caused to open and close proportionally.

Abstract: A valve body of an on-off valve that minimizes the deviation of opening and closing characteristics of a valve member made of an elastic polymer material and provided in a valve body of the on-off valve due to expansion caused by the fluid handled thereby and that maintains the specified opening and closing operation. A base portion of the valve member made with an elastic polymer material is inserted in an attachment hole of a valve element of a valve body with space constituted by a small-diameter-hole portion left at the hole bottom. A constricted-diameter portion formed in a tip opening of the attachment hole is embedded in the valve member to secure the base portion of the valve member. Axial elongation due to swelling of the valve member is distributed as forward elongation and rearward elongation sandwiching the site of securing by the constricted-diameter portion, which minimizes the axial elongation of a tip portion with a valve face and curtails deviation from the settings for on-off timing.

Abstract: The apparatus prevents fuel vapor from being discharged to an intake passage from a fuel metering chamber of a carburetor and maintains a substantially constant fuel pressure in the fuel metering chamber so as to stabilize the amount of the fuel discharged to the intake passage. The pump has a drive force produced by a pulsation pressure generated in a crank chamber of an engine or an intake tube. A discharge chamber of a fuel pump and a fuel tank are connected by a relief passage, and the relief passage is provided with a pressure regulating valve discharging a pressure equal to or greater than a set pressure in the discharge chamber to the fuel tank.

Abstract: A choke valve is fixed to a predetermined position even after manual release, whereby an improved start and a subsequent stable operation are obtained. A fixing force and a valve opening force are applied to a choke valve shaft. Further, a pin of a choke valve lever pushes an arm piece of a throttle valve lever to slightly open a throttle valve a choke valve is in a fully open position, and the choke valve opens half way to return the throttle valve to an idle position by a valve closing spring when a complete firing of the engine is achieved. When opening the throttle valve, a cam of the throttle valve lever pushes the pin to open the choke valve, a valve opening force overcomes a fixing force near the fully open position to set the choke valve to the fully open position, and the pin separates from the cam to open and close the throttle valve without interference with the choke valve.

Abstract: A starting apparatus of a diaphragm-type carburetor, a starting pump disposed at a convenient and accessible location which is separate from a carburetor main body, and air is prevented from being mixed into fuel, in such a structure constructed as a suction-type starting pump. A suction passage extends from a fuel metering chamber and extends beyond an outer portion of the carburetor main body. A starting pump conveniently disposed is separate from the carburetor, and an inlet check valve of the starting pump is disposed in the carburetor main body so as to reduce a volumetric capacity of a section extending to the inlet check valve from the fuel metering chamber, thereby preventing the air from remaining within the suction passage.

Abstract: A carburetor is provided that supplies an appropriate amount of fuel at engine start-up and in a specific range of rotational speed, and allows stable engine operation at a target rotational speed. The carburetor comprises a first fuel system (F1) for metering fuel from the constant fuel chamber (18) with a metering needle (32) linked to a throttle valve (5), and delivering the fuel to an air intake passage (2); and a second fuel system (F2) for controlling fuel compressed by a fuel pump (8) with an electromagnetically driven control valve (52) and delivering the fuel to the air intake passage (2); by supplying pressured fuel controlled by the control valve (52) in a predetermined specific range of rotation and controlling the rotational speed during start-up and warm-up, a target rotational speed can be maintained.

Abstract: A carburetor with a single fuel system that is capable of ensuring stable engine operation and lower fuel consumption. The fuel system comprises an electrical fuel control C that, in addition to mechanically coordinating the fuel flow rate with air intake by way of a metering needle 22 that operates in coordination with the throttle valve 3, opens and closes opening/closing valve 30 and cuts off and delivers fuel to the air intake passage 2 so as to maintain a required target rotational speed with little fuel consumption in a specific region of the degrees of opening of the throttle valve 3. Stable operation with minimal fluctuations in the rotational speed is ensured by cutting off the fuel when the rotational speed rises above the target rotational speed, and delivering the fuel when the rotational speed falls below the target rotational speed.

Abstract: The present invention facilitates the stabilization of the fuel flow rate in a single fuel system carburetor in which bleed air, mixed with fuel, is controlled by a metering needle moving in response to the movement of a throttle valve and the mixture is discharged into an intake channel. The present invention is directed to a carburetor in which an effective surface area of a metering hole is adjusted by a metering needle moving in response to the movement of a throttle valve, and the fuel introduced into a mixing chamber from a constant-fuel chamber under flow rate control with a metering hole is mixed with bleed air and discharged into an intake channel from a nozzle orifice. The mixing chamber has a volume providing for absorption and relaxation of changes in the negative pressure acting upon the nozzle orifice, the fuel is sucked in under stabilized negative pressure, and the air-fuel mixture with a preset air/fuel ratio is supplied over the entire operation range of the engine.

Abstract: The present invention facilitates proper control of the scavenging air and fuel-air mixture for a stratified scavenging two-cycle engine that is based on a crankcase compression/scavenging method, using any carburetor. The present invention includes a drive member, which rotates based on an accelerator operation, installed on the air valve of the air passage, wherein the drive member is movable through angular reciprocal movements. A slave member, which constantly contacts a cam provided on the drive member is installed on the throttle valve of the carburetor, and wherein the slave member is movable through linear reciprocal movements. A fuel flow-rate controlling mechanism works in cooperation with these linear reciprocal movements.

Abstract: A carburetor start pump circuit, for starting an engine has an auxiliary fuel pump mounted on a relatively standard carburetor body, a start pulse passage extending through the carburetor body to the auxiliary fuel pump, and a fuel circuit having an intake side which extends from a metering chamber of the carburetor body to the auxiliary fuel pump and a discharge side which is interconnected to the intake side and extends from the auxiliary fuel pump to a throttle bore in the air intake of the carburetor body. To prevent the engine from stalling, a restriction jet is placed within the start pulse passage to prevent the auxiliary fuel pump from discharging fuel into the throttling bore when the engine transmits pulses at high frequencies.

Abstract: The present invention provides a carburetor that can be adapted to a variety of engines with different positional relationships between the location for feeding the air/fuel mixture and the location for feeding scavenging air. The carburetor a carburetor main body (22) with an air intake passage (24) forming a portion of the air/fuel mixture passage (23) and is provided with an air passage (33) that forms a portion of an air channel (32) for scavenging air. The air passage (33) is positioned parallel to an air intake passage (24), and the front end thereof is positioned further to the base end side than to the engine-side front end face of the carburetor main body (22), enhancing the degree of freedom for placing the conduit pipe (34) for connecting the air passage (33) to the scavenging air feed port (9). Also, the throttle valve (26) and the air valve (35) are butterfly valves with mutually parallel valve stems, and the interlocking mechanism thereof has a simple configuration.

Abstract: The present invention facilitates proper control of the scavenging air and fuel-air mixture for a stratified scavenging two-cycle engine that is based on a crankcase compression/scavenging method, using any carburetor. The present invention includes a drive member, which rotates based on an accelerator operation, installed on the air valve of the air passage, wherein the drive member is movable through angular reciprocal movements. A slave member, which constantly contacts a cam provided on the drive member is installed on the throttle valve of the carburetor, and wherein the slave member is movable through linear reciprocal movements. A fuel flow-rate controlling mechanism works in cooperation with these linear reciprocal movements.

Abstract: The present invention facilitates increased output, decreased size, and simplified design and manufacture for a carburetor system in which a metering pin, which moves on a throttle valve, controls the fuel flow rate for a single fuel system. A carburetor of the present invention comprises a butterfly-like throttle valve on an air intake pathway with a nearly uniform diameter along its entire length, and a fuel nozzle positioned on the downstream side thereof. A metering pin retained by an actuating member that reciprocates linearly and remains in constant contact with a cam face of a cam member located on a valve stem. Fuel supplied to the air intake pathway from a constant fuel chamber via the fuel nozzle is controlled according to the opening and closing of a throttle. The metering pin by means of a cam controls the volume of the fuel flow rate at a desired stroke set irrespective of the opening and closing movement of the throttle valve.