Patents by Inventor Yoshihiro Niimura

Yoshihiro Niimura 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).

  • Two-shaft type rotary machine having a tip circle diameter to shaft diameter within a certain range
    Patent number: 4943214
    Abstract: A two-shaft rotary machine for use in a vacuum pump system includes rotors having a specific profile whereby any vibration and noise generated by the machine is minimized and its efficiency is increased. The number of lobes of each rotor is three or more. The tip and root portions of each rotor are defined by circular arcs, respectively, which are made smoothly continuous with each other through an involute curve. The ratio of the diameter of the tip circle to the diameter of the root circle is selected to fall within a range which is given by a specific expression.
    Type: Grant
    Filed: December 15, 1989
    Date of Patent: July 24, 1990
    Assignee: Ebara Corporation
    Inventors: Yoshihiro Niimura, Ritsuo Kikuta, Katsuaki Usui