A speed controlling method for a vehicle comprises obtaining a driving speed limit of a road ahead from a navigation system of the vehicle. A current driving speed of the vehicle is detected and if the current driving speed of the vehicle is greater than the limit ahead, a driver of the vehicle is informed that he must slow down in a distance between the vehicle and a speed measuring device located on the road ahead.

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.

An engine device including: an intake manifold configured to supply air into a cylinder; an exhaust manifold configured to output exhaust gas from the cylinder; a gas injector which mixes a gaseous fuel with the air supplied from the intake manifold; and a main fuel injection valve configured to inject a liquid fuel into the cylinder for combustion. At the time of switching the operation mode from one to the other between a gas mode and a diesel mode, an instant switching to the diesel mode is executed when the engine rotation number is determined to approach the upper limit value which leads to an emergency stop of the engine device.

In some embodiments, a vehicle is provided having improved fuel economy by using gradual engine speed control. Once a governor activation threshold is crossed, a dynamic engine speed limit that gradually increases over time is implemented. In some embodiments, if the engine speed does not continue to rise over time, increases in the dynamic engine speed limit may be paused. In some embodiments, if the engine speed increases at too great of a rate for too long of a time, the dynamic engine speed limit may be reset. In some embodiments, increasing, pausing, and/or resetting the dynamic engine speed limit allows gradual acceleration while also avoiding torque lock.

A system is provided for controlling operation of an engine brake system of an engine in a vehicle. The system includes a controller having an over-speed condition detection unit and an operation mode transition unit. The over-speed condition detection unit is configured to detect an over-speed condition based on a current engine speed and a fuel cut limit speed, the fuel cut limit speed being a predetermined engine speed at which fuel supplied to the engine is suspended. The operation mode transition unit is configured to control the operation of the engine brake system by transitioning the controller between a plurality of brake operation modes based on at least one transition parameter.

Provided are a work machine, a power unit, and a diesel engine of a work machine that make it possible to reduce emitted noxious substances to levels below reference values stipulated by exhaust gas regulations in advanced countries and regions while also omitting or simplifying a post-treatment device. A hydraulic pump is driven by a diesel engine that limits maximum output torque in a low revolution speed region lower than a high revolution speed region including a rated revolution speed in such a manner that the maximum output torque has a characteristic of intermediate torque lower than torque of a maximum output horsepower point at the rated revolution speed, and a hydraulic actuator is driven by hydraulic fluid delivered from the hydraulic pump.

With a torque-controlled internal combustion engine and a variable-speed transmission having fixed shift gear ratios, during a shift, the internal combustion engine is controlled in such manner that the drive output torque of the transmission remains the same before and after the shift.

The present disclosure includes a system for improving the perceived ease of operation in a work vehicle with an internal combustion engine. According to an aspect of the present disclosure, the system comprises a torque converter coupled at one end to the internal combustion engine and is coupled to a transmission at an opposite end via at least a transmission input shaft. The system also comprises at least two governors coupled to the internal combustion engine, wherein the governors are configured to adjust an operating parameter of the internal combustion engine. In addition, the system comprises a vehicle control unit communicatively coupled to the governors wherein the vehicle control unit is configured to receive a first and a second speed signal. This vehicle control unit commands the engine control unit to enable to at least one of the governors when a ratio of the first speed signal to the second speed signal exceeds a first predetermined threshold.

An engine device (21) including: an intake manifold (67) configured to supply air into a cylinder (77); an exhaust manifold (44) configured to output exhaust gas from the cylinder (77); a gas injector (98) which mixes a gaseous fuel with the air supplied from the intake manifold 67; and a main fuel injection valve (79) configured to inject a liquid fuel into the cylinder (77) for combustion. At the time of switching the operation mode from one to the other between a gas mode and a diesel mode, an instant switching to the diesel mode is executed when the engine rotation number is determined to approach the upper limit value which leads to an emergency stop of the engine device.

In some embodiments, a vehicle is provided having improved fuel economy by using gradual engine speed control. Once a governor activation threshold is crossed, a dynamic engine speed limit that gradually increases over time is implemented. In some embodiments, if the engine speed does not continue to rise over time, increases in the dynamic engine speed limit may be paused. In some embodiments, if the engine speed increases at too great of a rate for too long of a time, the dynamic engine speed limit may be reset. In some embodiments, increasing, pausing, and/or resetting the dynamic engine speed limit allows gradual acceleration while also avoiding torque lock.