Caterpillar Sarl

Caterpillar Inc.

Caterpilalr Sarl

Yuya Kanenawa

Tetsuya Yoshino

Nobuaki Matoba

Kouji Kishida

Yutaka Yokoyama

John James Krone

Keith Edward Lawrence

Shigeru Abe

Yoshiyuki Shimada

Nobuhiro Miki

Nick William Biggs

Sei Shimahara

Karl Arthur Kirsch

Shigeo Kajita

Shogo Tada

Shuhei Orimoto

Magomed Gabibulayev

Seiichi Akiyama

Yoshihiko Hata

Kenichi Yokota

Isao Konishi

Kazuya Miyamori

Takayasu Kitai

Mitsuhiro Toyoda

Shinya Ohmura

Genta Mine

Yujiro Yukimura

Problem to be solved: To provide a hydraulic circuit for the construction machine which enables to use the relief valve of low capacity in the work tool circuit. Solution: The hydraulic circuitfor a construction machine has: a hydraulic pumpof variable capacity, a work tooloperated by hydraulic oil delivered by the hydraulic pump, a work tool operating deviceto output a signal for operating the work tool, a control valveallowing the hydraulic pumpto supply the hydraulic oil to the work toolbased on the signal output from the work tool operating device, a tool's relief valveto release the hydraulic oil flowing between the control valveand the work tool, a pressure sensorto detect a pressure of hydraulic oil flowing into the work tool, and a controllerto reduce a delivery rate from the hydraulic pumpwhen the pressure detected by the pressure sensorexceeds a predetermined value.

Hydraulic circuit for a construction 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

In a control device, a pilot-operated first check valve connects a solenoid-operated first directional control valve to a lock side chamber of a lock cylinder installed in a quick coupler. A pilot-operated second check valve is connected to the lock cylinder unlock side chamber, a solenoid-operated second directional control valve connected between the second check valve and the first directional control valve. The first and second directional control valves are controlled by a controller with processed signals input from a mode selector switch, first sensor detecting a buck closing pilot pressure, and second sensor detecting a bucket closing working pressure.

Quick coupler control device for 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

In order to avoid cavitation in a boom cylinder head end at the beginning of a dig cycle, fluid from an alternate source is supplied to the head end before or in addition to fluid supplied by the main boom-up hydraulic circuit. In one embodiment, an electronic hydraulic valve, related sensors, and control system determines the beginning of a dig operation and uses fluid at an intermediate pressure to rapidly provide fluid to a boom head end cylinder to prevent voiding or cavitation before fluid under high pressure from the main pump can be brought to the cylinder. An on/off fluid switch is activated early in a dig operation to address low pressure at the boom cylinder head end and provide an alternate path for fluid into the cylinder in reaction to the boom being lifted by a motion of the stick and bucket in contact with the work surface.

Reducing dig force in hydraulic implements

In a work machine including a hydraulic pump (), a swing motor (), and swing relief valves (and), the amount of the swing operation (P) related to the swing motion of the swing motor () is detected, and the hydraulic pressure (P) supplied from the hydraulic pump () to the swing motor is also detected. Additionally, the required flow rate (F) of hydraulic oil required for the swing motor () is set based on the amount of the swing operation (P). In addition, the volume of relief (F) is estimated from the hydraulic pressure (P) based on the override characteristics of the swing relief valves (and). The discharge flow rate of the hydraulic pump () is controlled based on the value obtained by subtracting the volume of relief (F) from the required flow rate (F).

Hydraulic swing-controlling apparatus of work machine

The present invention is intended to provide a technology that can utilize the advantages of both a load sensing control and a regeneration circuit without causing any problem. A regeneration circuit is added to a hydraulic circuit provided with a hydraulic pressure signal line for detecting a hydraulic pressure value of a circuit and controlling a volume of hydraulic fluid to a cylinderwith reference to the detected value. A pressure reducing valvethat outputs a reduced pressure as an operating signal to a pump, and subsequently the controlling meanscauses the pressure reducing valveto output a pressure reduction command to a pumpand thus to reduce a discharge rate from the pump, when the regeneration circuit is in a regeneration state.

Method for controlling pump of working machine

Growing community of inventors

Tokyo, Japan

Yuya Kanenawa