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.

The invention relates to a method for adapting the composition of a mixture of fuel and combustion air. The mixture is supplied to a combustion chamber of a mixture-lubricated combustion engine in a work apparatus. The fuel is supplied to the combustion engine via a controlled fuel valve. In an operating state (I) of the combustion engine, the quantity of fuel is metered by the fuel valve. For the purpose of adapting the composition of the mixture, the combustion engine is shifted into a special operating state (II) which differs from the normal operating state (I). After starting, the combustion engine is operated in a first rotational speed range (B) for a prespecified operating time (T.sub.min), wherein, after the prespecified operating time (T.sub.min) has elapsed, the operating state (II) for adapting the composition of the mixture is initiated by a prespecified user action.

A system for combusting volatile vapors includes a carburetor having intake valves for receiving base fuel from a fuel source, ambient combustion air, and volatile vapors from a vapor source. A plurality of sensors measure and generate sensor data based on a respective plurality of physical properties associated with the carburetor and associate combustion engine operation. One or more programmable controllers receive the sensor data and control the intake valves to regulate respective ratios of the fuel, air, volatile vapors drawn through the carburetor based on the received sensor data. To increase the burn of volatile vapors, an engine loading system automatically operated by the controller(s) applies an automatically adjustable braking load on the engine. The load level applied is based on the sensor data and commensurate with maintaining stable engine running conditions. The loading system decreases time necessary to remediate a site.

To improve responsiveness of fuel supply control, a rotary carburetor 100 has a nozzle 8 including a fuel discharge port 8a and a needle 10 disposed coaxially with the nozzle 8 and disposed with a portion inserted into the nozzle 8. The needle 10 can be displaced relative to the nozzle 8 to change an effective area of the fuel discharge port 8a. The rotary carburetor 100 has an electric motor 14 for displacing the needle 10 along an axis, and a drive mechanism component 12 interposed between the electric motor 14 and the needle 10 and converting a rotational movement of the electric motor into a linear movement.

To improve responsiveness of fuel supply control, a rotary carburetor 100 has a nozzle 8 including a fuel discharge port 8a and a needle 10 disposed coaxially with the nozzle 8 and disposed with a portion inserted into the nozzle 8. The needle 10 can be displaced relative to the nozzle 8 to change an effective area of the fuel discharge port 8a. The rotary carburetor 100 has an electric motor 14 for displacing the needle 10 along an axis, and a drive mechanism component 12 interposed between the electric motor 14 and the needle 10 and converting a rotational movement of the electric motor into a linear movement.

To meet stringent emission standards and improve performance of two-stroke crankcase-scavenged engines, the muffler (13) of the engine is provided with mixing means (130, 31) for mixing the exhaust gases (42) resulting from the mixture participating in combustion and gases resulting from scavenging, so that a substantially homogenous gaseous mixture is formed within the muffler (13), and means (81) for sensing oxygen concentration is located in the homogeneous gaseous mixture and are configured to provide an output value to a control unit (80) for controlling supply of fuel to the engine and thereby the air-fuel ratio in the combustion chamber (41). The muffler (13) suitably is provided with a catalytic element (140), preferably a three-way catalyst. The engine (1) preferably is a stratified charge engine.

A garden tool includes a gasoline engine and a power source, the gasoline engine including a fuel supply system and an ignition system. The garden tool may further include a control system with at least one sensor used for collecting a working condition signal of the gasoline engine and a controller used for receiving the working condition signal and controlling the fuel supply system and/or the ignition system according to the working condition signal received. The power source may provide a power supply for the fuel supply system, the ignition system, and the control system through the controller.

An engine-driven working machine according to the present invention has a controller and a muffler. The controller is operated from starting of the engine in a rotational speed limitation mode in which the engine is prevented from rotating at a rotational speed that is higher than the predetermined limitation rotational speed. The controller forces to stop the engine, after a predetermined period has passed, during which the engine operates in the rotational speed limitation mode.

A system for combusting volatile vapors includes a carburetor having intake valves for receiving base fuel from a fuel source, ambient combustion air, and volatile vapors from a vapor source. A plurality of sensors measure and generate sensor data based on a respective plurality of physical properties associated with the carburetor and associate combustion engine operation. One or more programmable controllers receive the sensor data and control the intake valves to regulate respective ratios of the fuel, air, volatile vapors drawn through the carburetor based on the received sensor data. To increase the burn of volatile vapors, an engine loading system automatically operated by the controller(s) applies an automatically adjustable braking load on the engine. The load level applied is based on the sensor data and commensurate with maintaining stable engine running conditions. The loading system decreases time necessary to remediate a site.

The invention relates to a method for adapting the composition of a mixture of fuel and combustion air. The mixture is supplied to a combustion chamber of a mixture-lubricated combustion engine in a work apparatus. The fuel is supplied to the combustion engine via a controlled fuel valve. In an operating state (I) of the combustion engine, the quantity of fuel is metered by the fuel valve. For the purpose of adapting the composition of the mixture, the combustion engine is shifted into a special operating state (II) which differs from the normal operating state (I). After starting, the combustion engine is operated in a first rotational speed range (B) for a prespecified operating time (T.sub.min), wherein, after the prespecified operating time (T.sub.min) has elapsed, the operating state (II) for adapting the composition of the mixture is initiated by a prespecified user action.