Construction machine

Abstract

Provided is a construction machine including an engine with a supercharger, a capacity variable hydraulic pump driven by the engine, and a hydraulic actuator driven by hydraulic oil erupt from the hydraulic pump, and a controller to control absorption torque of the hydraulic pump, namely, pump torque. Until engine speed of the engine reaches target engine speed, the controller calculates target pump torque from a predetermined relationship between engine no-load speed and the target pump torque, corrects the target pump torque so as to make it smaller as the detected supercharging pressure is lower, and limits actual pump torque to the corrected target pump torque, until engine speed reaches target engine speed from engine speed lower than the target engine speed. Therefore, rapid raise of the rotation speed of the engine is achieved, while operation of the hydraulic actuator is carried out.

Description

technical field [0001] The present invention relates to a construction machine such as an excavator, and more particularly, to a construction machine provided with a controller for controlling a pump torque so that the engine speed increases rapidly from a low speed to a target speed. Background technique [0002] The background technology of the present invention will be described by taking an excavator as an example. [0003] The no-load rotational speed of an engine mounted on an excavator is usually determined by the operation of an engine rotational speed setter called an acceleration potentiometer and the selection of an operation mode (when there are multiple determining factors, select the lower value ) and so on to decide. The excavator controls the fuel injection amount in the engine by setting the determined rotational speed as a target engine rotational speed. [0004] On the other hand, an excavator equipped with an auto-deceleration function, when a pre-set d...

AI Technical Summary

Problems solved by technology

However, the countermeasure of suppressing the pump torque to the minimum in this way leads to the problem that the actuator operation, that is, the excavator operation cannot be substantially performed until the engine speed is completely increased.

This problem is not limited to deceleration and reset, but may also occur when the engine is raised from a low speed to the target speed, including when the engine is started.

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