Kawasaki Jukogyo Kabushiki Kaisha

Kobelco Construction Machinery Co., Ltd.

Kabushiki Kaisha Kawasaki Precision Machinery

Noboru Ito

Masahiro Matsuo

Yuko Funakubo

Hiroaki Fujiwara

Makoto Ito

Hiroshi Itoh

Takahiro Kobayashi

Ryo Yamamoto

Taisuke Tsunoo

Katsuki Yamagata

Masaaki Ehara

A valve device that changes the direction of flow of a hydraulic fluid supplied to and discharged from a cylinder mechanism to actuate the cylinder mechanism, the valve device including: a control valve including a main spool axially movable between different positions; a lock valve including a plunger and a pressure chamber; and a selector valve including a selector spool operable in conjunction with the main spool to axially move between different positions, the selector spool being located adjacent to the main spool and having an axis crossing an axis of the main spool.

Valve device

A solenoid flow control valve includes: an inlet passage that allows an inlet port to communicate with a pilot pressure chamber; an outlet passage that allows the pilot pressure chamber to communicate with an outlet port; a fixed restrictor provided on the outlet passage; a pilot spool that closes the inlet passage when a solenoid is in a non-excitation state, whereas when solenoid is in an excitation state, opens inlet passage at an opening degree corresponding to an input current value to generate a pilot pressure corresponding to the input current value in pilot pressure chamber, the pilot spool opening a bypass passage when input current value is less and closes bypass passage when input current value is greater than or equal to the predetermined value; and a main spool that controls a flow rate from inlet to outlet port in accordance with the pilot pressure chamber's pilot pressure.

Solenoid flow control valve

Provided is a configuration in which: a spool driven by an electromagnetic proportional solenoid is urged by a spool-returning spring configured to exert urging force in an opposite direction to a driving direction of the electromagnetic proportional solenoid; a mechanical stopper is disposed at the stroke end of the spool; current dither causes a control current to micro-vibrate, the control current driving the electromagnetic proportional solenoid; and the mechanical stopper includes a stopper-urging spring configured to allow the spool to vibrate owing to the current dither even when the spool is in contact with the mechanical stopper. A proportional solenoid control valve with this configuration is capable of reducing hysteresis at the stroke end of the spool by means of the current dither, and controlling the spool in a stable manner over the entire control range including the stroke end of the spool.

Proportional solenoid control valve

A pressure compensated electromagnetic proportional directional flow control valve of the present invention integrally includes: an electromagnetic proportional directional flow control valve configured to be driven by a solenoid; and a pressure compensated valve configured to carry out pressure compensation of a flow rate controlled by the electromagnetic proportional directional flow control valve. A pressure compensation spool moves so as to balance forces of a spring, a first pressure chamber, and a second pressure chamber. With this, the pressure compensation for maintaining a constant pressure difference between an upstream side and a downstream side of a first variable aperture can be carried out, and a surplus liquid of a liquid flowing from a liquid-pressure supply port to a derivation port can flow out from a branch port to outside.

Pressure compensated electromagnetic proportional directional flow control valve

A holding control valve of the present invention is configured such that: a spool is configured to perform strokes by a piston configured to operate by introduction of pilot pressure and have a larger diameter than the spool; the piston is divided into a pilot piston configured to receive the pilot pressure and a relief operation piston disposed adjacent to the spool to receive pressure of relief oil discharged when a relief valve operates; and the relief oil is introduced to between the pilot piston and the relief operation piston.

Holding control valve

The present invention provides a hydraulic circuit for a crane wherein a switching valve is provided between a plurality of motor circuits connected in series within the same actuator group, and at the time of simultaneous operation of the motor circuits, the switching valve is switched from a first position to a second position whereby the series connection between the motor circuits is cut off, and they are driven by each of separate hydraulic sources, thereby enabling prevention of pressure interference at the time of simultaneous operation of the motor circuits within the same actuator group without increasing hydraulic sources.

Growing community of inventors

Kobe, Japan

Noboru Ito