Kobelco Cranes Co., Ltd.

Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho

Takaharu Michida

Naoki Sugano

Naoto Hori

Katsuki Yamagata

Satoshi Maekawa

Hiroo Kondo

Naoya Kitazumi

Shintaro Sasai

Tomohiko Asakage

Kenji Onuki

Provided is a hydraulic drive apparatus for working machine capable of preventing an excessive pressure reduction on a meter-in side and moving a load in a lowering direction at a stable speed requiring no counter balance valve. The apparatus includes a hydraulic pump, a hydraulic actuator for lowering the load, an operating device, a hydraulic circuit including a meter-in flow passage, a meter-out flow passage and a regeneration flow passage, a control valve, a meter-in-flow-rate controller for controlling a meter-in flow rate, a meter-out-flow-rate controller for controlling a meter-out flow rate to one not lower than the meter-in flow rate, a back pressure generator located downstream of the regeneration flow passage in the meter-out flow passage, and a meter-out-flow-rate limiter. The meter-out-flow-rate limiter minimizes a flow passage area of the meter-out orifice when a pressure in the meter-in flow passage falls to or below a permissible pressure.

Hydraulic drive apparatus for work machine

Provided is a hydraulic drive apparatus for working machine capable of preventing an excessive pressure drop on a meter-in side and moving a load in a lowering direction at a stable speed requiring no counter balance valve, including a hydraulic pump, a first hydraulic actuator lowering a first load, an operating device, a first hydraulic circuit including meter-in and meter-out flow passages, a control valve, a meter-in-flow-rate controller, a meter-out-flow-rate controller making a meter-out flow rate not lower than a meter-in flow rate, a second hydraulic actuator, a second hydraulic circuit between the first hydraulic circuit and a tank and for the second hydraulic actuator, a back pressure valve between the second hydraulic circuit and the tank, a regeneration line leading a part of hydraulic fluid from between the second hydraulic circuit and the back pressure valve to the meter-in flow passage, and a check valve in the regeneration line.

Provided is a hydraulic driving apparatus for a working machine, preventing an excessive decrease in pressure on a meter-in side and moving a load at a stable speed in a lowering direction. The apparatus comprises: a hydraulic pump; a hydraulic actuator; a manipulation device; a working hydraulic circuit including a meter-in flow passage and a meter-out flow passage; a control valve for changing a state of supply of hydraulic fluid to drive the hydraulic actuator at a speed designated by the manipulation device; a meter-in flow adjuster and a meter-out flow adjuster adapted to adjust a meter-in flow rate and meter-in flow rate respectively to respective value corresponding to the speed designated by the manipulation device; and a relief valve. The meter-in and meter-out flow adjusters have respective flow adjustment characteristics such that the meter-in flow rate is greater than the meter-out flow rate.

Hydraulic driving apparatus for working machine

Provided is an apparatus to lower a load, comprising a hydraulic pump, a hydraulic actuator having first and second ports, a manipulation device, a hydraulic circuit including meter-in and meter-out flow passages for the first and second ports respectively and a regeneration flow passage with a check valve, a control valve, a meter-out flow controller adjusting a meter-out flow rate according to the manipulation device, a back pressure valve, and a non-regeneration operation relief valve whose set pressure is not less than a sum of a minimum set pressure of the back pressure valve, an inlet-outlet pressure difference of the meter-out flow controller when the meter-out flow rate is maximum and a discharge flow rate of the hydraulic pump is maximum, and an actuator pressure difference for driving the hydraulic actuator with no load, and not less than a maximum set pressure of the back pressure valve.

Provided is an apparatus provided in a working machine to lower a load, comprising a hydraulic pump, a hydraulic actuator, a manipulation device having a manipulation member, a meter-in flow control device, a meter-out flow control device, a back pressure valve, a regeneration fluid passage branched from the meter-out fluid passage at a position upstream of the back pressure valve and merged with the meter-in fluid passage, and a check valve. The meter-in flow control device controls a meter-in flow rate in a region of the meter-in fluid passage upstream of a merging point with the regeneration fluid passage. The meter-out flow control device controls a meter-out flow rate in a region of the meter-out fluid passage upstream of a branching point of the regeneration fluid passage so as to make the meter-out flow rate be greater than the meter-in flow rate.

Disclosed is a construction machine which comprises: a command changing regulation section; a loading device for imposing, on an engine, a load for raising an exhaust temperature of the engine up to a value at which particulate matter accumulated in a filter is burnt; and an instruction section for instructing the loading device to perform an operation for loading the engine. The instruction section prohibits the loading device from changing a loading level on the engine, during a period where a manipulation-state detection section detects a presence of a manipulation of a manipulation section. The command changing regulation section is set to a changing permission mode for permitting a value of a command which is to be assigned to an actuator control valve, to be changed according to changing a value of a command to be output from a manipulation device, during a period where the loading level is constant.

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Akashi, Japan

Takaharu Michida