Doosan Infracore Co., Ltd.

Doosan Corporation

Daewoo Heavy Industries Ltd.

Dal Sik Jang

Woo Yong Jung

Yong Lak Cho

Min Ha An

Kwang Ho Lim

A Reum Seo

Sung Ha Park

Young Sik Cho

Dong Ho Han

Hyeon Sik Ahn

Sang Woo Lee

Min Ha Ahn

Ki Nam Jung

Yoon Seok Jang

Jeong Hee Hong

Tae Kyung Kim

The present disclosure relates to a hydraulic system for a construction machine, and more particularly, to a hydraulic system for a construction machine including a plurality of actuators, in which each of the actuators includes a pump/motor, is operated under a control of a corresponding pump/motor, and stores working oil in an accumulator or receives the working oil supplemented from the accumulator in accordance with a difference between a flow rate entering the actuator and a flow rate discharged from the actuator.

Hydraulic system for construction machine

The present disclosure relates to a hydraulic system for construction equipment, and more particularly, to a hydraulic system, in which an actuator is controlled by a pump/motor. The hydraulic system for construction equipment according to the present disclosure includes logic valves in first and second hydraulic lines provided to an actuator, respectively, and when it is desired to operate the actuator in a state where an operation of the actuator is stopped by closing the logic valves, a pressure difference may be resolved by increasing pressure in sections of a pump/motor and the logic valves in advance even if a load is applied to the actuator, and thus the actuator may implement a desired operation without being affected by the load. That is, it is possible to improve operation controllability of the actuator.

Hydraulic system for construction equipment

An exemplary embodiment of the present specification relates to an apparatus for controlling a hydraulic pump for an excavator with respect to a change of an operation mode, the apparatus including: an operating unit configured to generate an operation signal according to an operation of an operator, and including a joystick or a pedal; an oil flow supplying unit configured to supply oil to actuators, in order to drive a plurality of actuators corresponding to the operation signal, and including a plurality of pumps and a plurality of logic valves; and a control unit configured to control the oil flow supplying unit by using a priority algorithm for each operation considering a use frequency and a load of the actuator with respect to a change of a predetermined operation mode according to the operation signal.

Apparatus and method for controlling oil hydraulic pump for excavator

The present disclosure relates to an energy reclaiming system for an electric forklift truck. The energy reclaiming system includes an electronic device operated by a motor when a working machine is raised and operated by a generator when the working machine is lowered, a hydraulic pump/motor connected to the electronic device and configured to perform two functions of a hydraulic pump and a hydraulic motor, a main control valve unit including a lift cylinder operating unit connected to the hydraulic pump/motor and configured to operate a lift cylinder and a secondary consumer operating unit connected to the hydraulic pump/motor and configured to operate a secondary consumer, and a control lever including a control valve configured to control the lift cylinder or the secondary consumer through the lift cylinder operating unit and the secondary consumer operating unit of the main control valve unit, respectively. The energy reclaiming system includes: a working fluid return line provided with a flow amount limiting valve configured to interrupt a flow of a return flow amount generated by the lift cylinder when the working machine (or fork carriage) is lowered; and an energy reclaiming unit installed in the working fluid return line and configured to, if a return flow amount generated when the working machine is lowered is smaller than a flow amount consumed by the secondary consumer, reclaim the return flow amount to an oil tank, and, if the return flow amount generated when the working machine is lowered is larger than the flow amount consumed by the secondary consumer, guide the return flow amount to the hydraulic pump/motor.

Energy reclaiming system for electric forklift truck

The present disclosure is a construction machine, such as an excavator, which comprises a plurality of hydraulically driven actuators, in which some of the actuators are provided in a one-to-one pump system where hydraulic pumps are connected to the respective actuators such that a working fluid is supplied from the respective pumps, and the remaining actuators are provided in an auxiliary control valve system where the working fluid is distributed by an auxiliary control valve connected to one or more pumps. When an amount of the working fluid of an actuator associated with the auxiliary control valve is insufficient, the actuator associated with the auxiliary control valve is connected to a pump of the one-to-one pump system to share the pump of the one-to-one pump system.

Pump control operating system of construction machine

A hydraulic pump controlling apparatus of a construction machine according to the present disclosure includes: a hydraulic pump in which a swash plate angle is controlled to control a discharge flow; an auxiliary pump; a control valve controlling a flowing direction of a fluid discharged from the hydraulic pump and selectively supplying the fluid to an actuator; an orifice and a relief valve connected between a center bypass line of the control valve and a tank T to be parallel to each other; signal pressure selecting units receiving a fluid passing through the center bypass line of the control valve and a fluid discharged from the auxiliary pump, and selecting the pressure of any one of the fluids as a signal pressure; and a regulator receiving the signal pressure selected from the signal pressure selecting units to control the swash plate angle of the hydraulic pump, and the signal pressure selecting unit selects the pressure of the fluid discharged from the auxiliary pump as the signal pressure and transfers the selected pressure to the regulator when the construction machine is in an idle state.

Hydraulic pump controller for construction machine

A fluid pump control system for excavators enables fluid pumps to produce hydraulic flows of a quantity great enough to actuate hydraulic actuators for smooth composite operations. The system includes variable displacement fluid pumps, fluid quantity control mechanisms for controlling the discharge quantity of the respective fluid pumps, fluid quantity control signal lines respectively connected to the fluid quantity control mechanisms, signal pressure control lines for bringing the fluid quantity control signal lines into connection with a fluid tank to drop the fluid quantity control signal pressures within the fluid quantity control signal lines, and a plurality of cutoff valves attached to the signal pressure control lines in tandem and shiftable in concert with the shifting movement of spools of a control valve for increasing the fluid quantity control signal pressures within the signal pressure control lines in proportion to the shifting amounts of the cutoff valves.

Fluid pump control system for excavators

A spool-out type booster brake valve device for industrial vehicles is configured to allow hydraulic working fluid to be supplied not only to a booster chamber but also to a master chamber thereby eliminating the need to use a separate brake fluid reservoir tank for supplementing brake fluid in the master chamber. The brake valve device is used in an industrial vehicle equipped with a fluid pump, a reservoir tank and a brake actuator. The brake valve device includes a valve body having an inlet port, a drain port, a brake port, a booster chamber communicatable with the pump via the inlet port and a master chamber communicatable with the brake actuator via the brake port. The master chamber is connected to the inlet port to receive working fluid from the pump. A valve spool is slidably fitted in the valve body through the booster chamber and the master chamber, the valve spool being shifted between an idle position and an operating position. The brake valve device also includes a booster sleeve and a master piston which are moved along with the valve spool in response to the shifting movement of the valve spool into the operating position, thereby reducing the volume of the master chamber so that the fluid in the master chamber can be introduced into the brake actuator via the brake port.

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Seoul, South Korea

Dal Sik Jang