Patents by Inventor Howard Brian James Stone

Howard Brian James Stone 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).

  • Valving for multi-stage vacuum pumps
    Patent number: 7318706
    Abstract: A multi-stage vacuum pump comprises a first piston in a first cylinder defining a first stage pumping chamber and a second piston in a second cylinder defining a second stage pumping chamber. The pump has a spool valve between the first and second cylinders for controlling flow from the first stage pumping chamber to the second stage pumping chamber. Either the first cylinder and the first piston or the second cylinder and the second piston being stepped so as to define a third stage pumping chamber. The spool valve is arranged to control the flow from the second stage pumping chamber to the third stage pumping chamber.
    Type: Grant
    Filed: August 18, 2004
    Date of Patent: January 15, 2008
    Assignee: Edwards Limited
    Inventors: Nigel Paul Schofield, Howard Brian James Stone