Power regeneration device for working machine and working machine

摘要

In a lowering operation of a boom, the amount of operation of a control lever is detected by a pressure sensor and input to a controller. Based on the input operation amount, the controller obtains a target flow rate Q0 of return oil discharged from a boom cylinder, calculates a deviation ΔQ between the target flow rate Q0 and an actual flow rate Q obtained from an actual rotation speed N of an electric motor acquired by a rotation speed sensor, calculates a signal Sm for controlling the opening area of a proportional solenoid valve in a manner allowing hydraulic fluid to flow to a control valve in just as much as ΔQ, and controls an operation pilot pressure of the control valve supplied from a sub-pump in accordance with the signal Sm so that the hydraulic fluid will flow to the control valve exactly in the amount of ΔQ.

主权项

1. A power regeneration device for a working machine equipped with a hydraulic actuator for driving a work device, a control valve for operating and controlling the hydraulic actuator, and a control lever device with a control lever for operating the control valve to activate the hydraulic actuator, the power regeneration device comprising:
a hydraulic motor driven by return oil from the hydraulic actuator; an electric motor connected mechanically to the hydraulic motor and driven thereby to generate electric power; an inverter which controls the rotation speed of the electric motor, and an electric storage device which stores the electric power generated by the electric motor; wherein the return oil discharged from the hydraulic actuator is branched and distributed to the side of the control valve and that of the hydraulic motor, the power regeneration device further comprising: a rotation speed detector which detects an actual rotation speed of the electric motor; an operation amount detector which detects the amount of operation of the control lever; a proportional solenoid valve which adjusts the opening area of the control valve, and a control device to which the rotation speed detected by the rotation speed detector and the operation amount detected by the operation amount detector are input; wherein the control device obtains a target flow rate of the return oil discharged from the hydraulic actuator and a target rotation speed of the electric motor based on the operation amount to control the rotation speed of the electric motor via the inverter in a manner attaining the target rotation speed of the electric motor, and obtains a deviation between the target flow rate and the actual flow rate of hydraulic fluid passing through the electric motor based on the target flow rate and on the actual rotation speed of the electric motor detected by the rotation speed detector, and controls the proportional solenoid valve based on the deviation obtained.