Shin Caterpillar Mitsubishi Ltd.

Caterpillar Sarl

Caterpilalr Sarl

Nobuaki Matoba

Kouji Kishida

Shigeo Kajita

Yoshihiko Hata

Naoyuki Moriya

Yuya Kanenawa

Yorimichi Kubota

Shinya Nozaki

Tetsuya Yoshino

Kazunori Yoshino

Hideto Furuta

Shogo Tada

Shuhei Orimoto

Yoshinori Yamagishi

Yoshikazu Kurokawa

Yoshiyuki Hibi

Yukihiro Uto

Mitsuhiro Toyoda

A hydraulic working machine is provided that uses a variable displacement pump and open center type flow rate control valve for a controlling a hydraulic actuator, and has a negative control throttle disposed in a center bypass oil passage to generate a negative control pressure. A hydraulic pump control system performs virtual bleed-off control for reducing the bleed-off flow rate of the center bypass oil passage, and can operate the hydraulic actuator with the same performance as an open center control. The control system includes a bypass cut valve disposed upstream from the negative control throttle to reduce flow through the center bypass oil passages, and a negative control pressure output valve that outputs a virtual negative control pressure. The control system is configured to reduce the bleed-off flow rate by operating the bypass cut valve when virtual bleed-off control is performed, and to reduce the pump flow rate by the bleed-off reduction flow rate.

Hydraulic pump control system of hydraulic working machine

Provided are a hydraulic circuit and a work machine capable of improving an initial motion speed of a hydraulic cylinder during a contraction of the hydraulic cylinder and securing a necessary pump flow rate while hydraulic fluid is being accumulated in an accumulator. Hydraulic oil from a head side of a second boom cylinder is regenerated in a first boom cylinder and the second boom cylinder through a second control valve of a regeneration circuit. At the same time, oil from the head side of the first boom cylinder is accumulated to a first accumulator by a pressure accumulating circuit through a first control valve. The hydraulic oil supplied under pressure from a main pump is fed to a rod side of the first boom cylinder by a boom control valve. A bleed-off valve of a bleed-off circuit communicates the first control valve to a tank at the time of initial operation of the first control valve, thereby releasing hydraulic oil from the head end of the first boom cylinder to improve an initial motion speed.

Hydraulic circuit and working machine

A control device for suppressing engine load fluctuation according to main pump circuit conditions, wherein an assist torque calculation task includes a target engine torque calculation task separating smooth torque components from main pump load torque and setting a minimum value of either smooth torque component or engine setting torque as target engine torque, and a subtractor calculating target assist torque based on a difference between the main pump load torque and the target engine torque, the assist torque calculation task controlling a capacity of an assist pump based on the target assist torque and controlling switching between an assist mode and a charge mode.

Control device and working machine

An inexpensive engine assist device capable of performing stable energy regeneration from an accumulator and a working machine on which the engine assist device is mounted are provided. A variable capacity type main pump and a variable capacity type assist pump are directly connected to an engine. A return pressure oil flowing out from a fluid pressure actuator is temporarily accumulated by a sub-accumulator and is supplied to an inlet of the assist pump, and the assist pump pressurizes the return fluid pressure oil and supplies the return fluid pressure oil to a main accumulator. A controller calculates and controls an assist pump swash plate angle, and assist starting torque or charge starting torque, and introduces a pressure-accumulated fluid discharged from the main accumulator to the inlet of the assist pump or introduces a pressurized fluid discharged from an outlet of the assist pump into the main accumulator.

Engine-assist device and industrial machine

A construction machine which is less vulnerable to theft compared with conventional machines is provided. The system includes an antenna () for detecting removal of an engine key () after the engine has stopped, an angle detector () for detecting a posture of the upper structure, and an anti-theft unit () for forcing the engine to stop and outputting an alarm signal in cases the upper structure is not in a given posture when parked.

Construction machine

A hydraulic circuit for a working machine is provided which prevents a decrease in the working speed of a clamshell bucket upon expansion of an expansion arm, so that improvement of the operability can be achieved. A hydraulic circuit for a working machine is configured such that a clamshell bucket is attached to a tip end of an expansion arm and the expansion arm and the clamshell bucket are operated by pressure oil supplied from a common pressure source. The operating pressure is reduced for driving the expansion arm to the expansion side based on the operating pressure for opening the clamshell bucket. By the configuration, the clamshell bucket can be opened rapidly, and improvement of the operability is achieved.

Hydraulic circuit of working machine

Device for controlling a working arm of a working machine

An electro-hydraulic transducing valve ( ) and other elements associated with cylinder-controlling components, such as a control valve ( ), are connected to the output end of a controller ( ) adapted to perform control computation based on electric manipulation signals send from and electric joy stick ( ) or the like. Control valve return pressure (P ) and load-sensing pressure (P ) are detected by the first and second detectors ( ), ( ) so that start-up of a hydraulic cylinder ( ) or the like is detected based on rise of the differential pressure (&Dgr;P) between the two types of pressures. The controller ( ) is provided with a function generating unit ( ) and a calibration computing unit ( ). The function generating unit ( ) has a reference function (F) that determines the relationship between electric manipulation signals and command values for commanding the electro-hydraulic transducing valve ( ) and other similar elements. The calibration computing unit ( ) is adapted to correct the reference function (F) by computing the calibration deviation (&Dgr;S) between the actual command value stored at the moment with the cylinder actually started and the provisional command value that corresponds to an imaginary start-up moment of the cylinder and has been set beforehand according to the reference function (F), and adding the calibration (&Dgr;S) to the reference function (F).

Method and device for controlling work machine

An apparatus for controlling the lifting operation comprising an operation mode selection switch which is selectively set to an ordinary operation mode or to a lifting operation mode and a hydraulic circuit isolating means. The hydraulic circuit isolating means isolates the hydraulic circuit into a running drive hydraulic circuit which feeds the pressurized fluid of one of the variable-capacity hydraulic pumps to the actuators of the running apparatuses when the operation mode selection switch is set to the lifting operation mode and a hydraulic circuit for driving the apparatus on the side of the turning body, which feeds the pressurized fluid of the other variable-capacity hydraulic pump to the actuators other than those of the running apparatuses.

Growing community of inventors

Hyogo, Japan

Nobuaki Matoba