Patents by Inventor Keith D. Waldo

Keith D. Waldo 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).

  • Oil free dry screw compressor including variable speed drive
    Patent number: 6474950
    Abstract: An oil-free dry screw compressor system is provided and includes a variable speed drive and motor along with control logic to increase or decrease the speed of the drive and motor based on sensed pressures. By using an electric motor and a rectifier/inverter drive, a variable speed compressor system is provided having a drive system that can be stopped and started an unlimited number of times over a given time period. Methods of controlling pressure in a compressor system including an oil-free dry screw compressor are also provided.
    Type: Grant
    Filed: July 13, 2000
    Date of Patent: November 5, 2002
    Assignee: Ingersoll-Rand Company
    Inventor: Keith D. Waldo