Yuken Kogyo Kabushiki Kaisha

Kenichi Hirano

Toshio Hashimoto

Yasuyuki Shingu

Koichi Ohba

Taku Nagano

Shiro Hattori

Tsuyoshi Kitamira

Eiji Mitsugi

Disclosed is a solenoid type electromagnetic operating device which needs a relatively large current only for a limited short period at an excitation start initial stage and is adapted to achieve the speeding up at an excitation start stage and an improvement in responsiveness as well as power saving without increasing a power load on each of a drive circuit and power supply. The device is used for exerting a mechanical output on a valve element against a spring force, and comprises a solenoid coil composed of a plurality of split coils mutually electrically independent, an iron core structure including a fixed core, a movable core and a yoke and assembled with the solenoid coil so as to form a magnetic path loop through which magnetic fluxes from the split coils pass in common, an excitation controller for selectively switching/controlling the excitation current to each split coil, and a transmission mechanism for transmitting the mechanical output based on the displacement of the movable core magnetically attracted to the fixed core to the valve element when one or more of the split coils are excited.

Electromagnetic operating device

A hydraulic power system includes a reversible pump, a variable-speed servomotor for driving the pump, a pressure sensor for detecting load pressure, a detector for detecting the motor speed, signal command units for generating preprogrammed pressure and flow rate commands, a rotational speed controller and a signal processor. The signal processor preferentially outputs a speed command corresponding to the flow rate command by a limiter operation when the difference signal between the pressure command and the pressure detection signal is higher than a predetermined level, whereas it preferentially outputs a speed command corresponding to the difference signal when the difference signal is equal to or lower than said level. The rotational speed controller controls the magnitude of a driving current supplied to the servomotor by a closed loop on the basis of the speed command and the detected signal so that the speed of the servomotor corresponds to the speed command.

Hydraulic power system

A hydraulic pump with a built-in electric motor wherein an electric motor and a pump unit are arranged in tandem fashion and accommodated within a common housing. In this pump, the housing is in the form of a metal box having a rectangular parallelepiped external shape and forms an electric motor frame fixedly accommodating a stator of the electric motor therein. A space in the metal box on the electric motor side is separated as a dry space from an internal space of said pump unit by a seal mechanism. At least one hydraulic oil receiving chamber is formed in a peripheral wall of the metal box, and the hydraulic oil receiving chamber is communicated with a passage for receiving return oil externally and another passage communicating with a suction port of the pump unit. The pump is capable of simultaneously achieving the cooling of a built-in electric motor and the prevention of contamination of hydraulic oil due to the rotation of the electric motor, without any possibility of electrical troubles with the built-in electric motor even if a water-containing hydraulic oil or aqueous hydraulic oil is fed and discharged.

Hydraulic pump with a built-in electric motor

A control circuit for a proportional electro-hydraulic fluid control valve in which during a transient condition with a feedback control signal varying rapidly the control loop is changed to an open loop to change the transient characteristic of the valve to prevent the occurrence of an abnormal surge. The control circuit includes a control loop changeover circuit designed so that when the error signal is greater than a predetermined level, the control mode of the magnitude control of a control output signal is changed from a closed loop control in accordance with the feedback signal to an open loop control in accordance with an input signal.

Growing community of inventors

Kanagawa, Japan

Kenichi Hirano