Komatsu Corporation

Wataru Sumino

Masatoshi Ikeda

Shinobu Nagura

Daisuke Kozuka

Akira Hasebe

Yuichi Hishinuma

Yuuki Yokoyama

A control method of an excavator including: a first circuit of an open circuit including a main valve controlling inflow of hydraulic oil from a main pump to a working equipment cylinder, and a tank to which the oil flowed out of the cylinder is ejected via the main valve; a second circuit of a closed circuit including a first valve between swing pump and motor; and a second valve on a first passage between the main valve and the tank, adjusting back pressure of the main valve, the control method includes: causing the oil to flow into a second passage around a spool of the first valve from an upstream portion of the first passage between the main valve and the second valve; and causing the oil to flow out of the second passage to a downstream portion of the first passage between the second valve and the tank.

Hydraulic system, excavator, and control method of excavator

An excavator includes: a swing motor driven by oil from a swing pump coupled to a power take-off and driven by an engine; a first main oil passage connecting a first discharge port of the swing pump and a first suction port of the swing motor; a second main oil passage connecting a second discharge port of the swing pump and a second suction port of the swing motor; a neutral retention valve disposed in the first main oil passage and the second main oil passage and controlling passage of oil; a regenerative energy absorbing device coupled to the power take-off and absorbs regenerative energy generated by oil from the swing motor to the swing pump via a meter-out opening of the neutral retention valve; and a valve control section controlling an area of the meter-out opening based on a state of the regenerative energy absorbing device.

Excavator and method of controlling excavator

A hydraulic system of an excavator includes a work state determination unit and a valve control unit. When it is determined that a work state of working equipment is a heavy excavation state, the valve control unit controls a first boom operation valve, a first arm operation valve, a first bucket operation valve, a second boom operation valve, a second arm operation valve, and a second bucket operation valve such that passing of hydraulic oil from a first hydraulic pump to a boom cylinder is restricted, hydraulic oil is supplied from a second hydraulic pump to a boom cylinder, hydraulic oil is supplied from both the first hydraulic pump and the second hydraulic pump to an arm cylinder, and hydraulic oil is supplied from one or both of the first hydraulic pump and the second hydraulic pump to a bucket cylinder.

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Tokyo, Japan

Wataru Sumino