Patents by Inventor Liu Changnian

Liu Changnian 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: 4972870
    Abstract: The invention relates to a brandnew multi-function static-errorless pressure control method and the valve thereof, in which a cylindrical two-side three-way valve is used as the pilot valve 20 and an asymmetric double-action differential hydraulic cylinder is used as the main valve 10 to constitute an 1-type static-errorless closed-loop negative feedback control system, a transfer means with special oil network connects to the oil circuits 1, 2, 8 and ports 4, 5, 9, L of the system and makes the valve to correspond to six operating modes of the relief valve, remote control relief valve, constant valve pressure reducing valve, constant difference pressure reducing valve, internal control sequence valve and external control sequence valve respectively. The test results have shown that the static error of the pressure control valve of present invention is 0.5%, the overshoot is less than 5%, and no self-excitation is found.
    Type: Grant
    Filed: September 12, 1989
    Date of Patent: November 27, 1990
    Inventors: Liu Changnian, Chen Zhe, Liu Silan