Patents Assigned to Hitachi Engineering Co.
  • Method and system for process control with complex inference mechanism using qualitative and quantitative reasoning
    Patent number: 5377308
    Abstract: A process control system for controlling a process exhibiting both linear behavior and non-linear behavior with a plurality of control quantities has a knowledge base storing therein universal facts, production rules including expert's empirical rules, meta rules describing flows of inferences, algorithm methods by mathematical expressions and membership functions referenced in fuzzy inference and a complex inference mechanism.
    Type: Grant
    Filed: February 5, 1993
    Date of Patent: December 27, 1994
    Assignees: Hitachi, Ltd., Hitachi Engineering Co.
    Inventors: Haruki Inoue, Motohisa Funabashi, Masakazu Yahiro, Yoshiyuki Satoh
  • Capacitive load driving device
    Patent number: 4733106
    Abstract: A device for driving a capacitive load, comprising a first switching element responsive to an external control signal for selectively conducting a charge current therethrough to the load, a second switching element responsive to the external control signal for conducting a discharge current from the load and a generator for generating from the discharge current a cutoff signal to be applied to the first switching element to ensure turn-off of the latter.
    Type: Grant
    Filed: April 1, 1985
    Date of Patent: March 22, 1988
    Assignees: Hitachi, Ltd., Hitachi Engineering Co.
    Inventors: Mitsuhiko Okutsu, Tatsuo Shimura, Tadaaki Kariya
  • Reference voltage circuit
    Patent number: 4725770
    Abstract: A reference voltage circuit in which an output reference voltage is stabilized against variations in power source as well as in transistor current amplification factor h.sub.FE.
    Type: Grant
    Filed: February 11, 1987
    Date of Patent: February 16, 1988
    Assignees: Hitachi, Ltd., Hitachi Engineering Co.
    Inventors: Mitsuhiko Okutsu, Tatsuo Shimura, Tadaaki Kariya, Kazuyoshi Masuda
  • Apparatus for making diagnosis of valve device in turbine system
    Patent number: 4523286
    Abstract: A diagnostic apparatus for diagnosising of a valve device in a turbine system comprises at least one of a pressure sensor for sensing hydraulic pressure in a hydraulic cylinder for driving a valve body of the valve device and a position sensor for sensing the displacement of the valve body, and a processing device for processing the output signal from the above-mentioned at least one sensor. The processing device has an offset computing device which receives a signal representing the actual operating state of the valve device obtained on the basis of the output signal from the at least one sensor and a signal corresponding to a reference value obtained under the normal operating state of the valve device. The offset computing device is operable to compute the offset between the signals received thereto. A judging device is provided for judging as to whether or not there is a symptom of a sticking in the valve device, in accordance with the output signal from the offset computing device.
    Type: Grant
    Filed: August 5, 1982
    Date of Patent: June 11, 1985
    Assignees: Hitachi, Ltd., Hitachi Engineering Co., Hitachi Service Engineering Co., Ltd.
    Inventors: Tsuguaki Koga, Hidesumi Kuwashima, Hidenori Inoue, Hidetoshi Hamaoka, Hiroshi Ohta