Abstract: In an apparatus for controlling an air/fuel ratio of a general-purpose internal combustion engine using mixed fuel containing alcohol and gasoline and operated at a desired engine speed inputted by the operator while a throttle opening is regulated such that a detected engine speed converges to the inputted desired engine speed, a fuel injection amount determined for mixed fuel based on fuel injection amount characteristics is increased/decreased when a load is kept constant and the output air/fuel ratio is estimated to correct the fuel injection amount by the estimated air/fuel ratio, while a switch (knob) is installed to be manipulated by the operator to switch the fuel injection amount characteristics.

Abstract: An engine working machine that has an electronically controlled fuel injection system and a fuel tank disposed in an upper portion. The capacity of the fuel tank is effectively used and a complex structure is prevented while reducing the length of the fuel piping. An engine is disposed in a lower portion, and a fuel tank is disposed above the engine. A fuel pump is mounted on a bottom outside surface of the fuel tank, and disposed projecting on a side portion of the crankcase. An extended box is provided on a bottom surface of the fuel tank, and the fuel pump is mounted with a filter and a fuel intake port located inside the extended box. The fuel pump is housed in a pump case that is fixed to a bottom surface of the extended box.

Abstract: In an apparatus for controlling an air/fuel ratio of a general-purpose internal combustion engine using mixed fuel containing alcohol and gasoline and operated at a desired engine speed inputted by the operator while a throttle opening is regulated such that a detected engine speed converges to the inputted desired engine speed, a fuel injection amount prepared for mixed fuel is increased/decreased when a load is kept constant and the output air/fuel ratio (at which an output of the engine becomes maximum) is estimated. A rate of alcohol contained in the fuel is estimated from the estimated air/fuel ratio and the fuel injection amount is corrected based on the estimated alcohol rate, thereby determining the fuel injection amount appropriately in accordance with the estimated alcohol rate.

Abstract: An engine working machine that has an electronically controlled fuel injection system and a fuel tank disposed in an upper portion. The capacity of the fuel tank is effectively used and a complex structure is prevented while reducing the length of the fuel piping. An engine is disposed in a lower portion, and a fuel tank is disposed above the engine. A fuel pump is mounted on a bottom outside surface of the fuel tank, and disposed projecting on a side portion of the crankcase. An extended box is provided on a bottom surface of the fuel tank, and the fuel pump is mounted with a filter and a fuel intake port located inside the extended box. The fuel pump is housed in a pump case that is fixed to a bottom surface of the extended box.

Abstract: An electronic control system for a carburetor, includes: a transmission device linked to a valve; an electric actuator for driving the valve; and an electronic control unit for controlling operation of the electric actuator, the electric actuator being disposed between the transmission device and the electronic control unit, The transmission device, the electric actuator and the electronic control unit are housed and held in a casing mounted on the carburetor. A ventilation apparatus which places an interior of the casing in communication with an outside atmosphere relative to the carburetor is connected to the casing.

Abstract: In a blowby gas treatment system for a multiple cylinder engine, in which: a first cylinder and a second cylinder are provided to the engine; a first fuel supply device that always operates during operation of the engine is connected to the first cylinder; and a second fuel supply device that is capable of stopping an operation thereof during the operation of the engine is connected to the second cylinder, first and second branch pipes of an intake manifold are connected to the first and second cylinders, and a blowby gas outlet of a breather chamber and a blowby gas inlet opening into the first branch pipe communicate with each other via a breather pipe, the breather chamber collecting a blowby gas of the engine. Accordingly, when any of the cylinders is stopped, it is possible to easily prevent a blowby gas from flowing toward the stopped cylinder.

Abstract: In an intake control system for a general-purpose engine, comprising: a motor which is attached to a first side wall, supporting one end portion of a valve shaft of a throttle valve, of a throttle body, and which drives the throttle valve to be opened and closed; a sensor unit which is attached to a second side wall supporting the other end portion of the valve shaft, and which detects an opening degree of the throttle valve; a fuel injection valve which is attached to a third side wall integrally connecting upper end portions of the first and second side walls to each other, and through which a fuel is injected into the intake path at a position downstream of the throttle valve; and an electronic control unit which is attached to a fourth side wall facing the third side wall, the electronic control unit is connected to the motor, the fuel injection valve and the sensor unit with first, second and third conducting wires, respectively.

Abstract: In an apparatus for controlling an air/fuel ratio of a general-purpose internal combustion engine using mixed fuel containing alcohol and gasoline and operated at a desired engine speed inputted by the operator while a throttle opening is regulated such that a detected engine speed converges to the inputted desired engine speed, a fuel injection amount determined for mixed fuel based on fuel injection amount characteristics is increased/decreased when a load is kept constant and the output air/fuel ratio is estimated to correct the fuel injection amount by the estimated air/fuel ratio, while a switch (knob) is installed to be manipulated by the operator to switch the fuel injection amount characteristics.

Abstract: In an apparatus for controlling an air/fuel ratio of a general-purpose internal combustion engine using mixed fuel containing alcohol and gasoline and operated at a desired engine speed inputted by the operator while a throttle opening is regulated such that a detected engine speed converges to the inputted desired engine speed, a fuel injection amount prepared for mixed fuel is increased/decreased when a load is kept constant and the output air/fuel ratio (at which an output of the engine becomes maximum) is estimated. A rate of alcohol contained in the fuel is estimated from the estimated air/fuel ratio and the fuel injection amount is corrected based on the estimated alcohol rate, thereby determining the fuel injection amount appropriately in accordance with the estimated alcohol rate.

Abstract: An electronic control system for a carburetor, includes: a transmission device (24, 25) linked to a valve (7, 8); an electric actuator (20, 21) for driving the valve (7, 8); and an electronic control unit (12a) for controlling operation of the electric actuator (20, 21). The transmission device (24, 25), the electric actuator (20, 21) and the electronic control unit (12a) are housed and held in a casing (10) mounted on the carburetor (C). The ventilation means (72, 74, 74?, 89, 90) for causing an interior of the casing (10) to communicate with the outside is connected to the casing (10). Therefore, it is possible to house the transmission device, the electric actuator and the electronic control unit efficiently in a common casing so as to downsize the electronic control system for a carburetor, and improve durability of the electronic control unit and the electric actuator.

Abstract: In a system for controlling a general-purpose air-cooled internal combustion engine having two cylinders each equipped with a throttle valve and a fuel injector, and a cooling fan that selectively directs air onto the cylinders, a throttle driver selectively drives the respective throttle valve of each cylinder to open or close. The system also includes an injector driver that selectively drives the respective injector of each cylinder to open, and a controller that controls operation of the throttle driver and injector driver in such a way that the throttle opening and an amount of fuel to be injected are different for each cylinder, such that an engine speed becomes substantially constant, thereby enabling the engine to obtain desired output characteristics.

Abstract: A fuel injection control system corrects the amount of fuel injected by fuel injection valves toward an increased side when an acceleration state resulting from operation of a throttle occurs. A control unit includes a detector, an acceleration state determinor, and an acceleration corrector. When an increase in the detected value is a predetermined value or more within a first predetermined time period, the acceleration state determiner determines that a state is an acceleration state and inputs a signal inducing fuel-amount-increase correction to the acceleration corrector. When the state where an amount of change in the detected value reaches a predetermined value or more in an increasing or decreasing direction within a first predetermined time period continuously occurs a predetermined number of times or more before a second predetermined time period expires, determination of the acceleration state is stopped until a third predetermined time period passes.

Abstract: To a first bank B1 and a second bank B2, a first throttle body T1 and a second throttle body T2 placed between the banks B1, B2 are attached, respectively, in such a manner that an axis A3 of an intake path 8 of each of the first throttle body T1 and the second throttle body T2 is substantially perpendicular to an axis A2 of a corresponding one of the banks B1, B2. Each of the throttle bodies T1, T2 has a throttle valve 9 pivotally supported therein and the fuel injection valve 10 injecting fuel to the intake path 8 at a part downstream of the throttle valve 9. The throttle valve 9 of each of the first and second throttle bodies T1, T2 is placed in such a manner that an axis A4 of a valve shaft 9a of the throttle valve 9 is substantially orthogonal to the axis A3 of the corresponding intake path 8 and is substantially parallel to the axis A2 of a corresponding one of the banks B1, B2.

Abstract: In an intake control system for a general-purpose engine, comprising: a motor which is attached to a first side wall, supporting one end portion of a valve shaft of a throttle valve, of a throttle body, and which drives the throttle valve to be opened and closed; a sensor unit which is attached to a second side wall supporting the other end portion of the valve shaft, and which detects an opening degree of the throttle valve; a fuel injection valve which is attached to a third side wall integrally connecting upper end portions of the first and second side walls to each other, and through which a fuel is injected into the intake path at a position downstream of the throttle valve; and an electronic control unit which is attached to a fourth side wall facing the third side wall, the electronic control unit is connected to the motor, the fuel injection valve and the sensor unit with first, second and third conducting wires, respectively.

Abstract: In a blowby gas treatment system for a multiple cylinder engine, in which: a first cylinder and a second cylinder are provided to the engine; a first fuel supply device that always operates during operation of the engine is connected to the first cylinder; and a second fuel supply device that is capable of stopping an operation thereof during the operation of the engine is connected to the second cylinder, first and second branch pipes of an intake manifold are connected to the first and second cylinders, and a blowby gas outlet of a breather chamber and a blowby gas inlet opening into the first branch pipe communicate with each other via a breather pipe, the breather chamber collecting a blowby gas of the engine. Accordingly, when any of the cylinders is stopped, it is possible to easily prevent a blowby gas from flowing toward the stopped cylinder.

Abstract: A fuel injection control system corrects the amount of fuel injected by fuel injection valves toward an increased side when an acceleration state resulting from operation of a throttle occurs. A control unit includes a detector, an acceleration state determinor, and an acceleration corrector. When an increase in the detected value is a predetermined value or more within a first predetermined time period, the acceleration state determiner determines that a state is an acceleration state and inputs a signal inducing fuel-amount-increase correction to the acceleration corrector. When the state where an amount of change in the detected value reaches a predetermined value or more in an increasing or decreasing direction within a first predetermined time period continuously occurs a predetermined number of times or more before a second predetermined time period expires, determination of the acceleration state is stopped until a third predetermined time period passes.

Abstract: In a system for controlling a general-purpose internal combustion engine having two cylinders each equipped with a throttle valve and a fuel injector, and a cooling fan that sucks in and blows air onto the cylinders, there are provided a throttle driver that drives the throttle valve of each cylinder to open/close, an injector driver that drives the injector of each cylinder to open and a controller that controls operation of the throttle driver and injector driver in such a way that the throttle opening and an amount of fuel to be injected are different for each cylinder, such that an engine speed becomes constant, thereby enabling to obtain desired output characteristics.

Abstract: In a lawnmower engine speed control system having an actuator moving a throttle valve and a controller controlling operation of the actuator such that the engine speed becomes equal to a predefined desired engine speed, it is determined whether the lawnmower is under a mowing operation based on a value indicative of a load of the engine including an operation rate or output of the engine, the desired engine speed is changed based on a result of determination, thereby enabling to lower noise, to boost fuel efficiency, and to simplify operation by making manual regulation of engine speed unnecessary, while ensuring stable operation free from engine speed variance.

Abstract: In an engine speed control system mounted on a walk-behind truck having a bed that carries cargo, to power driven wheels through a clutch such that the truck runs and the engine speed is controlled to a desired engine speed, it is detected whether the operator performs operation for disengaging the clutch or for turning the truck, and the desired engine speed is determined to a first value when the operator does not perform any of the operations, while determining it to a second value (lower than the first value) when the operator performs the clutch disengaging or truck turning operation, thereby preventing lurching and sharp turning, protecting cargo against being damaged and falling off, and minimizing fuel consumption and noise.

Abstract: In an engine control system mounted on a machine such as a walk-behind truck through a CVT and having an actuator whose operation is controlled such that a detected engine speed becomes equal to a desired engine speed, the output of the engine is estimated based on the detected engine speed and a detected throttle opening, the desired engine speed is changed when the estimated engine output is greater or smaller than output threshold values, and a speed reduction ratio of the CVT is also changed based on the detected engine speed such that a detected speed of the CVT output shaft speed becomes equal to a desired output shaft speed, thereby enabling to reduce the fuel consumption and noise of the engine.