Hitachi Construction Machinery Co., Ltd.

Hitachi Industrial Equipment Systems Co., Ltd.

Masami Ochiai

Takashi Kanai

Genroku Sugiyama

Toichi Hirata

Tsutomu Udagawa

Hideyo Kato

Yutaka Watanabe

Morio Oshina

Yukihiko Sugiyama

Ken Ichiryu

Yusaku Nozawa

Takashi Yagyu

Mitsuo Sonoda

Kazuo Takiguchi

Mitsuo Aihara

Teruo Igarashi

Kazuhisa Ishida

Kouji Funato

Koji Nozaki

Toshimi Sakai

Yasuo Tanaka

Takatoshi Ooki

Yoshinori Furuno

Akira Hashimoto

Gen Yasuda

Nobuhiko Ichiki

Sotaro Tanaka

Akira Nakayama

Koji Ishikawa

Katsumi Ueno

Takashi Yagyuu

Atsushi Tanaka

Shinobu Higashi

Hirotsugu Kasuya

Yuusaku Nozawa

Yoshiomi Jojima

A swing drive system for a construction machine enhances safety for an operator. A swing control meansA has a lever input amount-torque tableand an actual rotating speed-torque table. Based on a lever input amount and an actual rotating speed of an electric motor, the tables are used to derive torque values. A minimum value of the torque values is taken as the acceleration torque. The swing control meansA further has a lever input amount-meter-out restriction area tableand an actual rotating speed-relief torque table. Based on the lever input amount and the actual rotating speed of the electric motor, a meter-out restriction area is derived from the lever input amount-meter-out restriction area table and the actual rotating speed to calculate a meter-out torque. A minimum value of the meter-out torque and relief torque is taken as the braking torque.

Swing drive system for construction machine

A hydraulic drive system comprises directional flow control valves (-) for selectively supplying a hydraulic fluid from a first hydraulic pump (), inflow control valves (-) disposed respectively in branch lines (A-C) branched from a supply line () for supplying a hydraulic fluid delivered from a second hydraulic pump () to rod pushing-side chambers (A,A,A,A) of hydraulic cylinders, a bypass flow control valve () disposed in a line () connecting the supply line () and a reservoir (), and a controller () for computing control variables corresponding to operation command signals from control levers () and controlling the inflow control valves (-) and the bypass flow control valve () in accordance with the computed control variables. Thus, the number of flow control valves and the length of piping required for their connection can be reduced, and a total pressure loss can be further reduced.

Hydraulic driving system of construction machinery

The control valve apparatus holds a seat valve member in a position seated on a valve seat to thereby prevent a backward flow even if the pressure in the inlet chamber side becomes lower than the pressure in the outlet chamber side. With a pilot control valve member is in a closed state, when the pressure in the inlet chamber is higher, a pressurized medium is introduced to the control pressure chamber via a first valve unit and is cut off from the outlet chamber by a second valve unit. When the pressure in the outlet chamber is higher, the pressurized medium is introduced to the control pressure chamber via the second valve unit and is cut off from the outlet chamber by the first valve unit.

Control valve apparatus and pressure circuit

Fault diagnosis of hydraulic pumps is made automatically during an actual operation of a working machine, particularly when there is a problem with horsepower limiting control of the hydraulic pumps. A controller performs horsepower limiting control for a plurality of variable displacement hydraulic pumps to . The controller measures a pump delivery pressure and pump delivery rate of each hydraulic pump when the pump delivery rate reaches a maximum during operation of the hydraulic drive system based on their detected values, collects the measured values as fault diagnostic data, and then compares a calculated target pump delivery rate with the collected pump delivery rate to decide if there is a fault of the hydraulic pump.

Pump trouble diagnosing device for hydraulic drive device and display device of the diagnosing device

A winch over-winding prevention apparatus includes: a winch drum that is driven for up/down hoist in response to a command issued through an operating lever; a stop switch that is activated when a suspended object raised or lowered as a hoisting cable wound around the winch drum is further taken up or fed out is hoisted up to a predetermined stop position; and a stop device that stops drive of the winch drum when the stop switch is activated, and further includes: a speed detection device that detects a hoist speed of the suspended object; a speed reduction device that reduces a drive speed of the winch drum once the suspended object reaches a predetermined speed reduction start position; and a speed reduction control device that calculates a deceleration rate of the winch drum in correspondence to the hoist speed of the suspended object detected by the speed detection device and controls drive of the speed reduction device in response to a speed reduction command corresponding to the deceleration rate.

Overwinding prevention device for winch

A swivel control apparatus according to the present invention , includes: a hydraulic pump; a hydraulic motor for swiveling which is driven by hydraulic oil emitted from the hydraulic pump; a control valve which controls a flow of hydraulic oil which is supplied from the hydraulic pump to the hydraulic motor for swiveling, and at a neutral position of the control valve cuts off from one another a pair of ports which communicate to input and output ports of the hydraulic motor; a valve device which communicates and cuts off from one another a pair of conduits which are respectively connected to the input and output ports of the hydraulic motor for swiveling; a pressure detection device which detects respective pressures in the two conduits and outputs pressure signals; a rotational speed detection device which detects a physical quantity based upon a rotational speed of the hydraulic motor for swiveling and outputs a rotational speed signal; a mode selection device which selects a neutral brake mode and a neutral free mode; and a control device which controls driving of the valve device so as to cut off the two conduits from one another when the neutral brake mode is selected, and so as to communicate the two conduits based upon the pressure signals and the rotational speed signal when the neutral free mode is selected.

Swivel control apparatus

A hydraulic drive system for a supersized hydraulic working machine such as a hydraulic excavator includes hydraulic pumps connected to main lines through a delivery line and a supply line. Branch portions from the main line include flow control valves for allowing a hydraulic fluid to flow from the hydraulic pumps toward hydraulic cylinders. A hydraulic reservoir is connected to the main lines through a reservoir line and a drain line. Other branch portions for the drain line include flow control valves for allowing a hydraulic fluid to flow from the hydraulic cylinders toward the hydraulic reservoir. A line branched for the delivery line includes a bypass valve for supplying the hydraulic fluid delivered from the hydraulic pumps to the supply line at a desired flow rate and returning the remaining hydraulic fluid to the hydraulic reservoir.

Hydraulique drive device

Apparatus for diagnosing failure of hydraulic pump for work machine

Hydraulic drive system

A flow control system is arranged in a hydraulic circuit provided with a variable displacement hydraulic pump, plural actuators and a pump controller. The pump controller controls the displacement of the pump so that a delivery pressure becomes higher by a predetermined value than a maximum load pressure of the plural actuators, whereby the flow rate of pressure oil to the actuators is controlled. The system includes plural valve units connected between the pump and the actuators. Each valve unit has an operating and correcting variable restrictors. The system also includes pressure compensation valves, which are each arranged on an upstream side of a restrictor group consisting of the operating and correcting variable restrictors. The opening of the pressure compensation valve is independently set by an opening drive force set based on a downstream pressure of the restrictor group, an opening drive force set by a pressure-difference setting device and a closing drive force set based on an upstream pressure of the restrictor group so that the upstream pressure becomes higher by a predetermined pressure than the downstream pressure of the restrictor group.

Growing community of inventors

Atsugi, Japan

Masami Ochiai