A method of evaluating operating capability of a prime mover includes: starting the prime mover with a minimum load requirement threshold; obtaining a reference prime mover operation parameter for the prime mover; comparing the reference prime mover operation parameter with a standard prime mover operation parameter to determine a reference matrix; and adjusting via a TRS controller a standard operation threshold based on the reference matrix to obtain an optimal operation threshold.

An engine-driven working machine including a controller by which a time period until the rotation speed limitation mode is canceled can be shortened. After a throttle valve is moved to a fully-closed position by an operation to allow the engine to finish the fast idling state and while the engine is transited to an idling state, the controller cancels the rotation speed limitation mode by detecting an event in which a cycle period of rotation speed variations of the engine is longer than a cycle period of rotation speed variation in the fast idling state.

The power equipment such as a lawn mower (10) comprises an internal combustion engine (100) having a plurality of cylinders, an engine control unit (110) for selectively deactivating at least one of the cylinders, a work implement such as a cutting blade (70) connected to the engine in a power transmitting relationship, a clutch (80) provided in a power transmission path between the engine and the work implement, and a central control unit (50) for controlling an operation of a propelling device, the clutch and the engine control unit. The central control unit is configured to start the engine with two or more of the cylinders activated, to cause the engine control unit to operate the engine at a prescribed rotational speed, and to cause the engine control unit to deactivate at least one of the cylinders when the engine has reached a stable state at the prescribed rotational speed.

The lawn mower (10) comprises an internal combustion engine (100) having a plurality of cylinders, an engine control unit (110) for selectively deactivating at least one of the cylinders, a cutting blade (70) supported by a lawn mower main body via a cutter deck, and connected to the engine in a power transmitting relationship, a clutch (80) provided in a power transmission path between the engine and the cutting blade, a height adjustment mechanism (90) provided on the cutter deck for adjusting the height of the cutting blade, and a central control unit (50) for controlling an operation of the height adjusting mechanism, the clutch and the engine control unit. The central control unit is configured to cause the engine control unit to deactivate at least one of the cylinders when a prescribed operating condition is met, and to raise the cutting blade to a prescribed elevated height before deactivating the at least one of the cylinders.

The invention concerns a method for controlling the fuel supply to an internal combustion engine at start-up, the engine having a fuel supply system. The invention also concerns a carburetor having a fuel supply system including a main fuel path connecting a diaphragm controlled regulating chamber to a main outlet in the region of the venturi section, the main fuel path including an actively controlled fuel valve, and an idling fuel path branching off from the main fuel path downstream of the valve and ending in at least one idling outlet in the region of a throttle valve, the fuel supply system further including a start fuel line starting upstream or downstream of the fuel valve and ending in at least one start fuel outlet to the intake channel.

An altitude fuel limiter and method for controlling an engine using the same is provided. The altitude fuel limiter includes a torque screw sleeve extending from an inboard end to an outboard end. The torque screw sleeve has an interior surface defining a central bore extending axially within the torque screw sleeve. A plunger is disposed within the central bore and moves axially between a first position and a second position. A plunger regulator senses ambient pressure and is coupled with the plunger to axially displace the plunger toward the inboard end of the torque screw sleeve to the first position in response to sensing an ambient pressure that is below a predetermined pressure. The predetermined pressure may be associated with non-compliant altitudes and the plunger limits fuel delivered to the engine when displaced to the first position.

An engine is configured such that, during the starting of the engine, when it is being detected that throttle opening has been set at a starting position, if it is detected that the engine speed has exceeded a predetermined speed slightly lower than a speed when a centrifugal clutch becomes an engaged state, a control unit retards the ignition timing from a general angle to a first angle BTDC, and then advances the ignition timing to a second angle at predetermined intervals, and holds the ignition timing at the second angle for a predetermined time period, thereby preventing the engine from stopping due to fouling on the spark plug while suppressing the engine speed at the speed when the centrifugal clutch becomes the engaged state, or less.

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.

Provided is an engine working apparatus capable of smoothly decelerating an engine. The engine working apparatus includes: an internal combustion engine including a piston reciprocally movable in a cylinder and a combustion chamber defined by the piston; an ignition plug configured to ignite air-fuel mixture in the combustion chamber; a detector configured to detect a rotation number of the internal combustion engine; and a controller configured to control an ignition timing of the ignition plug based on the detected rotation number, execute feedback control of determining the ignition timing based on a deviation between a target rotation number and the detected rotation number, and to execute the feedback control when the detected rotation number satisfies a predetermined deceleration condition.

Disclosed is a method for regulating the speed of an engine which drives a disengageable device. The regulation of the engine speed is effected in accordance with a first mode when the disengageable device is disengaged and in accordance with a second mode when the disengageable device is engaged. The determination is effected by: —estimating the resistive torque exerted on the engine by the disengageable device; —changing a binary value from a first value representative of the disengaged state to a second value representative of the engaged state when the estimated resistive torque is higher than a first predetermined threshold for a first predetermined period of time; and —changing the binary value from the second value to its first value when, for a second predetermined period of time, the estimated resistive torque is lower than a second threshold possibly equal to the first threshold.