Hitachi Construction Machinery Co., Ltd.

Hitachi Construction Machinery

Nobuhiko Ichiki

Yusaku Nozawa

Kinya Takahashi

Yoshizumi Nishimura

Mitsuhisa Tougasaki

Hiroshi Matsuzaki

Minoru Aoki

Ken Ichiryu

Masami Ochiai

Takashi Kanai

Kazuyuki Ino

Kaoru Endo

Kunihiko Yoshida

Kenichi Koshi

Hiroyasu Masubuchi

Wataru Ohtsu

Wataru Otsu

A joystick for an electro-hydraulic control system is provided with a rotary potentiometer having a pivotable arm. This pivotable arm is integrally arranged on a rotary shaft and pivots responsive to pivotal control of a joystick in a predetermined direction or a direction opposite to the predetermined direction. The joystick is also provided with a torsion coil spring for normally holding the pivotable arm in a neutral position, a pin arranged on the pivotable arm and capable of expanding the torsion coil spring upon pivotal movement of the pivotable arm, a holding pin for holding the torsion coil spring at its coil portion, and a cover member having a pair of guide portions for limiting movements of the coil portion of the torsion coil spring in the predetermined direction and the opposition direction when the torsion coil spring is in its neutral position.

Joystick for electro-hydraulic control system

A recovery check valve,and a piston valve,are axially slidably disposed within a spool,in coaxial relation. An axial fluid passage,is formed within a cylindrical portion,of the piston valve,and a seat portion,for the recovery check valve is formed at an open end of the cylindrical portion,The cylindrical portion,of the piston valve is formed with a hole,through which a hydraulic fluid in the fluid chamber,is introduced to a bridge passage,when the spool,is operated so as to introduce a hydraulic fluid from a hydraulic pump to the bottom side of a hydraulic cylinder. Fluid passages,are formed within the spool so that a hydraulic fluid in the bridge passage,is introduced to the closed end of the piston valve through the fluid passages when the spool is operated in the opposite direction. With such a structure, the size of the valve apparatus can be set to the same size as the directional control valve not provided with the recovery check valve.

Directional control valve device

Pressure compensating valves

Directional control valve with flow distribution valves

Hydraulic control system

Hydraulic drive system

High-speed solenoid valve apparatus

A solenoid operated valve apparatus in which a solenoid device includes an inner yoke, a plunger guide disposed in the opposed relationship with the inner yoke, a plunger movably accommodated in s space formed between the inner yoke and the plunger guide, a bobbin frame disposed to surround the inner yoke and said plunger guide, a coil wound around the bobbin frame, and an outer yoke disposed to surround the coil. The bobbin frame is made of a polymeric material, and is adhered to the inner yoke and the plunger guide in a unitary structure.

Solenoid operated valve apparatus

A fluid control valve apparatus comprises logic valve means including a valve housing, a first valve member defined in the valve housing, and an axially movable valve body arranged in the first valve chamber, with the valve body including opposite end portions and a conical surface portion brought into contact with the conical surface portion when the valve body is moved in a valve closing direction. First and second hydraulic fluid chambers are defined in the valve housing and communicate with each other when the conical surface portion is out of contact with the valve seat and out of communication when the conical surface portion contacts the valve seat. A first pilot chamber in the valve housing, adjacent one end portion of the valve body, biases the valve body in a closing direction by a first pilot pressure signal. A second valve chamber is defined in the valve housing with an extension of the valve body being formed by extending the other end portion of the valve body through the first hydraulic fluid chamber, and is arranged in the second valve chamber for axial movement. An independent second pilot chamber biases the valve body in an opening direction by a second pilot pressure signal.

Fluid control valve apparatus

Growing community of inventors

Ibaraki-ken, Japan

Nobuhiko Ichiki