Hitachi Construction Machinery Co., Ltd.

Kazuyoshi Hanakawa

Mariko Mizuochi

Akinori Ishii

Tsuyoshi Nakamura

Makoto Mitsuhashi

Masayuki Norita

A drive control system for a work machine. A gradual stoppage command and an operation speed limitation command are calculated and output. A pilot pressure is corrected such that, upon a stoppage operation of a control lever, a drive actuator is stopped gradually; and the pilot pressure is corrected such that an operation speed of the drive actuator is limited. A supply of the pilot hydraulic fluid to the speed increasing unit is interrupted when a failure of a speed increasing solenoid proportional valve of the speed increasing unit is detected.

Drive control system for work machine

The work machine includes a stabilization control calculation unit that calculates and outputs a gradual stoppage command for making a drive actuator stop gradually and an operation speed limitation command for limiting an upper limit operation speed according to the status of stability of the work machine, a stoppage characteristic modification unit that corrects pilot pressure so as to make the drive actuator stop gradually when a stoppage operation is performed on a control lever, and an operation speed limitation unit that corrects the pilot pressure so as to limit the operation speed of the drive actuator.

Work machine

A hydraulic circuit system for a hydraulic excavator, which has a hydraulic circuit for an attachment, includes: a directional control valvethat supplies a hydraulic fluid to an attachment connected to the hydraulic circuit for an attachment; a first over-load relief valve unitthat is provided in one of lines of the hydraulic circuit for an attachment; a second over-load relief valve unitthat is provided in the other of the lines of the hydraulic circuit for an attachment; a first proportional solenoid valvethat controls set relief pressure of the first over-load relief valve unit; and a second proportional solenoid valvethat controls set relief pressure of the second over-load relief valve unit. The attachment having various characteristics and capacity, such as a hydraulic breaker or a crusher, can be applied to the hydraulic circuit for an attachment in a simple configuration.

Growing community of inventors

Tsuchiura, Japan

Kazuyoshi Hanakawa