Patents by Inventor Edward H. Fletcher

Edward H. Fletcher 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).

  • Electrohydraulic valve system
    Patent number: 4437385
    Abstract: A control system for controlling a double-acting cylinder includes four pilot-operated, proportional-type poppet valves for controlling fluid flow between the cylinder, a pump and a reservoir. Four solenoid-controlled pilot valves operate the poppet valves in response to error signals generated by a control circuit. The control circuit receives a cylinder position feedback signal and an operator-generated command signal. The control circuit provides for float, shutdown, variable deadband and pressure adjustment operation.
    Type: Grant
    Filed: April 1, 1982
    Date of Patent: March 20, 1984
    Assignee: Deere & Company
    Inventors: Kenneth D. Kramer, Edward H. Fletcher
  • Electrohydraulic valve system
    Patent number: RE33846
    Abstract: A control system for controlling a double-acting cylinder includes four pilot-operated, proportional-type poppet valves for controlling fluid flow between the cylinder, a pump and a reservoir. Four solenoid-controlled pilot valves operate the poppet valves in response to error signals generated by a control circuit. The control circuit receives a cylinder position feedback signal and an operator-generated command signal. The control circuit provides for float, shutdown, variable deadband and pressure adjustment operation.
    Type: Grant
    Filed: January 22, 1990
    Date of Patent: March 17, 1992
    Assignee: Deere & Company
    Inventors: Kenneth D. Kramer, Edward H. Fletcher