Yuken Kogyo Kabushiki Kaisha

Yasuyuki Shingu

Kenichi Hirano

Susumu Yoshino

Takashi Yoshioka

Toshio Hashimoto

Akira Ohashi

Koichi Ohba

Taku Nagano

Eiji Mitsugi

Masao Egi

Siro Hattori

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 variable displacement piston pump of the type in which the hydraulic pressure in a pressure chamber of an output flow variable element is controlled by a proportional electro-hydraulic control valve to control the displacement of the variable element against a spring to vary the output flow within a range between a maximum output flow and a full cut-off and the output pressure or both the output pressure and the output flow of the pump are controlled electro-hydraulically through a closed loop. The variable displacement piston pump includes flow detector for generating an electric signal corresponding to the output flow of the pump, pressure detector for generating an electric signal corresponding to the output flow of the pump, and control amplifier responsive to the difference between a flow setting signal and the output signal of the flow detector to control a driving control current supplied to the proportional electro-hydraulic control valve and also responsive to the detected output pressure reaching a predetermined value to control the driving control signal in accordance with the difference between a pressure setting signal and the output signal of the pressure detector.

Variable displacement piston pump

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.

Control circuit for proportional electro-hydraulic fluid control valves

Growing community of inventors

Kanagawa, Japan

Yasuyuki Shingu