Abstract: An engine-driven working machine includes a controller, which varies a control value of a solenoid valve so as to decrease or increase an opening degree of the solenoid valve when a rotating speed of an engine is within a predetermined high rotating speed range and the rotating speed of the engine is lower or higher than a predetermined rotating speed, respectively. When the control value of the solenoid valve is varied so as to decrease the opening degree of the solenoid valve and corresponds to a predetermined opening degree larger than a fully-closed state, the control value is set to a limitation value.

Abstract: An engine-driven working machine includes a controller, which varies a control value of a solenoid valve so as to decrease or increase an opening degree of the solenoid valve when a rotating speed of an engine is within a predetermined high rotating speed range and the rotating speed of the engine is lower or higher than a predetermined rotating speed, respectively. In case the controller determines that the engine-driven working machine gets started saw cutting, the controller stops varying the control value of the solenoid valve when the rotating speed of the engine is within the predetermined high rotating speed range and lower than the target rotating speed.

Abstract: A speed reduction method for a hand-carried engine-driven working machine is provided in which a speed reduction of an engine can be attained reliably and safely by preventing the occurrence of lean come-down phenomenon in such a state that the engine is operating in a practical revolution speed range. An acceleration is calculated based on a change in revolution speed, and when the acceleration becomes smaller than a predetermined threshold, an ignition timing is retarded by a desired amount based on a determination that the engine is being decelerated, and further, a fuel flow rate is also increased, whereby the decelerated state of the engine is maintained without fail, so that the occurrence of lean come-down phenomenon is prevented in the process of reducing the revolution speed of the engine.

Abstract: The opening of a solenoid valve is automatically adjusted after an engine is started and before actual work is performed for an appropriate air-fuel ratio, whereby it is possible to attain a good and stable driving of the engine without any delay even for an abrupt change in load. After the engine is started, when a rotation speed enters a “fuel flow rate adjusting rotation speed range” in which a definite load is applied to the engine in a working rotation speed range of the engine in which a throttle valve is opened to a definite opening, a detected rotation speed is fed back to a target rotation speed, and the opening of the solenoid valve is controlled to adjust a fuel flow rate, so that the combustion state in the engine is optimized at the valve opening so determined.

Abstract: A method for making an optimum combustion during engine operating time changes a fuel flow rate of the solenoid valve on the basis of engine rotational speed feedback control during engine idling time at low engine rotational speed and low electric power consumption. During engine idling time of an engine are carried out a rotational speed detecting process, an idle rotation adjusting process of making a rotational speed detected by the rotational speed detecting process equal to an initial value of rotational speed by controlling an ignition timing while comparing the detected rotational speed with the initial value of rotational speed as target value, and a valve opening correction process according to idle ignition timing change (I.I.T.C.) obtained by the idle rotation adjusting process. The valve opening is set to an adjusted valve opening (A.V.O.) plus a correction valve opening (C.V.O.) by the valve opening correction process.

Abstract: The opening of a solenoid valve is automatically adjusted after an engine is started and before actual work is performed for an appropriate air-fuel ratio, whereby it is possible to attain a good and stable driving of the engine without any delay even for an abrupt change in load. After the engine is started, when a rotation speed enters a “fuel flow rate adjusting rotation speed range” in which a definite load is applied to the engine in a working rotation speed range of the engine in which a throttle valve is opened to a definite opening, a detected rotation speed is fed back to a target rotation speed, and the opening of the solenoid valve is controlled to adjust a fuel flow rate, so that the combustion state in the engine is optimized at the valve opening so determined.

Abstract: A speed reduction method for a hand-carried engine-driven working machine is provided in which a speed reduction of an engine can be attained reliably and safely by preventing the occurrence of lean come-down phenomenon in such a state that the engine is operating in a practical revolution speed range. An acceleration is calculated based on a change in revolution speed, and when the acceleration becomes smaller than a predetermined threshold, an ignition timing is retarded by a desired amount based on a determination that the engine is being decelerated, and further, a fuel flow rate is also increased, whereby the decelerated state of the engine is maintained without fail, so that the occurrence of lean come-down phenomenon is prevented in the process of reducing the revolution speed of the engine.

Abstract: A method for making an optimum combustion during engine operating time changes a fuel flow rate of the solenoid valve on the basis of engine rotational speed feedback control during engine idling time at low engine rotational speed and low electric power consumption. During engine idling time of an engine are carried out a rotational speed detecting process, an idle rotation adjusting process of making a rotational speed detected by the rotational speed detecting process equal to an initial value of rotational speed by controlling an ignition timing while comparing the detected rotational speed with the initial value of rotational speed as target value, and a valve opening correction process according to idle ignition timing change (I.I.T.C.) obtained by the idle rotation adjusting process. The valve opening is set to an adjusted valve opening (A.V.O.) plus a correction valve opening (C.V.O.) by the valve opening correction process.

Abstract: Oil level detection sensor detects an oil level in a crankcase. First charging circuit includes a serial connection of a first charging capacitor for charging a reverse voltage produced in a primary coil, the detection sensor, and a first diode. Thyristor is turned on, in response to voltage-charging of the first charging capacitor, to disable an ignition operation of an ignition circuit. Second charging circuit includes a serial connection of a second charging capacitor for charging a forward voltage, produced in the primary coil, and a second diode. Transistor is turned on, in response to voltage-charging of the second charging capacitor, to disable a turning-on operation of the thyristor.

Abstract: Oil level detection sensor detects an oil level in a crankcase. First charging circuit includes a serial connection of a first charging capacitor for charging a reverse voltage produced in a primary coil, the detection sensor, and a first diode. Thyristor is turned on, in response to voltage-charging of the first charging capacitor, to disable an ignition operation of an ignition circuit. Second charging circuit includes a serial connection of a second charging capacitor for charging a forward voltage, produced in the primary coil, and a second diode. Transistor is turned on, in response to voltage-charging of the second charging capacitor, to disable a turning-on operation of the thyristor.

Abstract: The invention simplifies the structure of a magneto generator and stabilizes the operation of an internal combustion engine at the time of start-up, thereby providing an ignition device simplified in structure and reduced in size and providing improved safety to the internal combustion engine. In an ignition device for a capacitive discharge internal combustion engine, an ignition timing signal is calculated with a cycle detection signal obtained at a timing at which a forward voltage portion of an output voltage from a generator coil has reached a cycle detection voltage for making continual ignition operations available, and a peak voltage detection signal and a start-up voltage detection signal are obtained in accordance with a delayed reverse voltage portion of the output voltage from the generator coil. In a preset normal region speed or less in which a load is coupled to the engine, an ignition signal is output immediately after the peak voltage detection signal has been generated.

Abstract: A method and an apparatus for driving an auxiliary device of an internal combustion engine according to the present invention is directed to preventing an over revolution of an engine by detecting a speed of the revolution of the engine, regardless the magnitude of an induced voltage of a primary winding of an ignition device.

Abstract: The present invention discloses a system which utilizes the storage action of capacitors and the characteristic of the turn-off operation due to a potential difference between the base and emitter of a transistor, and immediately after a primary short-circuit current flowing through a primary winding of an ignition coil has reached a maximum, that is, immediately after a forward induced voltage in the primary winding has reached a maximum, the primary short-circuit current is cut off in accordance with information in which the forward induced voltage in the primary winding is at its maximum to always effect the ignition operation immediately after the primary short-circuit current is at its maximum.