Patents Assigned to Varco, Inc.
  • Solid state controller
    Patent number: 4276502
    Abstract: An improved alternating current prime mover control system and method for, for example, the control of a valve position or other physical variable whose state can be sensed or calculated wherein the state of the physical variable is compared with a reference variable to generate, in conjunction with a waveform generator, a fixed amplitude signal that has variable time duration which feeds a part of the control system that drives the alternating current prime mover source in more than one direction.
    Type: Grant
    Filed: April 28, 1978
    Date of Patent: June 30, 1981
    Assignee: Varco, Inc.
    Inventor: Harry S. Elliott
  • Solid state controller
    Patent number: 4112342
    Abstract: An improved alternating current prime mover control system and method for, for example, the control of a valve position or other physical variable whose state can be sensed or calculated wherein the state of the physical variable is compared with a reference variable to generate, in conjunction with a waveform generator, a fixed amplitude signal that has variable time duration which feeds a part of the control system that drives the alternating current prime mover source in more than one direction.
    Type: Grant
    Filed: September 27, 1976
    Date of Patent: September 5, 1978
    Assignee: Varco, Inc.
    Inventor: Harry Samuel Elliott