Patents by Inventor Rudolph E. Yeh

Rudolph E. Yeh 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).

  • Directional control valve with integral flow control valve
    Patent number: 4574839
    Abstract: The present invention is a pressure compensated directional control valve. The present invention allows the flow rate to a given hydraulic implement to be constant regardless of the load imposed upon the hydraulic implement or the hydraulic pressure supplied by the hydraulic pump. Pressure compensation is achieved by a piston mounted within a sleeve valve insert wherein the piston moves to create a variable orifice to control the amount of hydraulic fluid supplied to the hydraulic implement. The desired flow rate is maintained regardless of changes in the supply pressure and the implement load pressure. The present invention eliminates the need for two separate valves for directional flow control and pressure compensation, without increasing the casing size of the flow control auxiliary valve.
    Type: Grant
    Filed: April 19, 1984
    Date of Patent: March 11, 1986
    Assignee: J. I. Case Company
    Inventors: Rudolph E. Yeh, Joseph L. Zagotta