Methods and systems for operating a vehicle powertrain that includes an engine and a transmission including a power take off output are presented. In one non-limiting example, engine speed may be adjusted responsive to a level of a signal input to a controller. The controller may select an operating mode responsive to the level of the signal input to the controller.

To satisfy both a request for ensuring worker's safety at the engine start and a worker's request for promptly starting a work, on the premise of a working machine including an engine RPM suppression mode.

A working machine (1) has a centrifugal clutch (6). The engine RPM suppression mode is executed at the start of an internal combustion engine (2). With the RPM suppression mode, the RPM of the internal combustion engine (2) is controlled not to exceed a clutch-in RPM. The working machine (1) has a mode cancelling means (S5) canceling the engine RPM suppression mode when a predetermined mode cancelation condition for cancelling the engine RPM suppression mode is satisfied, and a cancellation condition changing means (S2) changing the mode cancelation condition depending on a change in an engine operational state and/or an environment.

A vessel propulsion system includes an engine that provides a propulsive force to a vessel, a throttle valve to adjust an air amount supplied to the engine, an accelerator operation unit operated by an operator to adjust a throttle opening degree, the throttle opening degree corresponding to an operation amount of the accelerator operation unit, and a control unit programmed to vary an engine output even when the throttle opening degree is maintained at a fixed value other than an idling opening degree, the engine output corresponding to the operation amount of the accelerator operation unit as a reference output.

An energy-saving and durable linkage mechanism for electronic engine speed regulation of generator sets, comprises an inverter, a stepping motor, a buffer linkage assembly for engine speed regulation, and a carburetor shaft. The stepping motor is electrically connected to the inverter, and the buffer linkage assembly for engine speed regulation is provided between the stepping motor's output shaft and carburetor shaft. The buffer linkage assembly for engine speed regulation comprises a crank I, crank II, link, and buffer spring. Crank I's one end is fixed to the stepping motor's output shaft, and crank II's one end is fixed to the carburetor shaft's upper end. The crank I's free end is provided with link hook hole I and spring hook hole I, and the crank II's free end is provided with link hook hole II and spring hook hole II. The invention achieves throttle opening control and buffering function with long service life.

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 for mixed fuel determined based on fuel injection amount characteristics 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. And the fuel injection amount is corrected based on the estimated air/fuel ratio, thereby enabling to estimate the output air/fuel ratio without using an expensive air/fuel ratio sensor and to feedback-control the fuel injection amount such that the engine is operated at the output air/fuel ratio.

Constant-speed-travel-apparatus controlling prime-mover so that mobile-body mounted with the prime-mover travels at constant-speed, includes: function-operation-member being instructed activation of speed-maintaining-function of the mobile-body in response to operation by operator; first-speed-operation-member being instructed the travel-speed of the mobile-body in accordance with operation-amount by the operator; second-speed-operation-member being instructed change of the travel-speed by predetermined amount in response to operation by the operator in state where activation of the speed-maintaining-function has been instructed through the function-operation-member; and electronic-control-unit controlling output of the prime-mover based on the operation-amount of the first-speed-operation-member and number of times of operation of the second-speed-operation-member so that the mobile-body travels at constant-speed in the state.