Patents by Inventor John Mitchel Cobb

John Mitchel Cobb 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).

  • Hydraulic jar and an overpressure relief mechanism therefor
    Patent number: 7814995
    Abstract: A hydraulic jar for a drilling assembly is disclosed. In some embodiments, the hydraulic jar includes a tubular housing, a mandrel disposed in the housing, an annulus between the mandrel and the housing, and a pressure relief mechanism disposed in the annulus. The pressure relief mechanism generally divides the annulus into first and second portions. The pressure relief mechanism includes first and second annular members in engagement with one another when the pressure in the second annulus portion is less than a predetermined value and a fluid flow path between the first and second annulus portions. The fluid flow path has a first size when the pressure in the second annulus portion is less than the predetermined value, and a second size that is larger than the first size when the pressure in the second annulus portion becomes equal to or greater than the predetermined value.
    Type: Grant
    Filed: March 19, 2008
    Date of Patent: October 19, 2010
    Assignee: National Oilwell Varco, L.P.
    Inventors: Jeffery Ronald Clausen, Jonathan Ryan Prill, John Mitchel Cobb
  • Hydraulic Jar and an Overpressure Relief Mechanism Therefor
    Publication number: 20080236894
    Abstract: A hydraulic jar for a drilling assembly is disclosed. In some embodiments, the hydraulic jar includes a tubular housing, a mandrel disposed in the housing, an annulus between the mandrel and the housing, and a pressure relief mechanism disposed in the annulus. The pressure relief mechanism generally divides the annulus into first and second portions. The pressure relief mechanism includes first and second annular members in engagement with one another when the pressure in the second annulus portion is less than a predetermined value and a fluid flow path between the first and second annulus portions. The fluid flow path has a first size when the pressure in the second annulus portion is less than the predetermined value, and a second size that is larger than the first size when the pressure in the second annulus portion becomes equal to or greater than the predetermined value.
    Type: Application
    Filed: March 19, 2008
    Publication date: October 2, 2008
    Applicant: NATIONAL OILWELL VARCO, L.P.
    Inventors: Jeffery Ronald Clausen, Jonathan Ryan Prill, John Mitchel Cobb