Patents by Inventor Takeshi Ohira

Takeshi Ohira has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4150734
    Abstract: An elevator car control apparatus is disclosed in which a three-phase AC tachometer generator is coupled to a motor for driving an elevator car, and the AC output of the tachometer generator is full-wave rectified for use as a speed feedback voltage. A waveform-shaping circuit generates one pulse for each cycle of the output of the AC tachometer generator. A counter counts such pulses after the car has passed a deceleration-initiating point, thereby producing the number of counts proportional to a car running distance after the passage of the deceleration-initiating point. From this number of counts, a deceleration command voltage decreasing progressively in accordance with car positions is obtained by a decoder and a digital-analog converter. During deceleration, the car-drive motor is subjected to feedback control in accordance with the difference between the speed feedback voltage and the deceleration command voltage, thus effecting deceleration control of the elevator car.
    Type: Grant
    Filed: January 24, 1978
    Date of Patent: April 24, 1979
    Assignee: Hitachi, Ltd.
    Inventors: Takeshi Ohira, Tadao Kameyama, Chihiko Honzyo, Yuzaburo Iwasa, Takanobu Hatakeyama
  • Patent number: 4042069
    Abstract: In an AC elevator which is provided with a multi-speed induction motor unit connected to an AC power source and including a high-speed motor and a low-speed motor and in which an elevator car is started and accelerated by the high-speed motor, a control system comprising regenerative braking means connecting the low-speed motor to the AC power source through one set of thyristors connected in parallel in opposite polarity, DC braking means for supplying direct current to the high-speed motor from a controlled reactifier circuit, means for controlling the regenerative braking means to reduce the speed of the elevator car, means for detecting the reduction of the speed of the elevator car to a level at which the regenerative braking means is no more effective in producing the regenerative braking torque, and means for deenergizing the regenerative braking means and energizing the DC braking means in response to the output of the detecting means.
    Type: Grant
    Filed: March 4, 1975
    Date of Patent: August 16, 1977
    Assignee: Hitachi, Ltd.
    Inventors: Takeshi Ohira, Akinori Watanabe