Patent ID: 9255456
Filing Date: 2016-02-09
CPC Classification: E21B

Claim Text:
1. A dump valve for use with a positive displacement motor in a drill string comprising: a housing having an inlet and an outlet; an axially movable flow sleeve positioned within the housing and forming with the housing an annular space in communication with pressure exterior to the valve; and sealed against fluid communication with the interior of the housing in both an open and a closed position of the valve; the flow sleeve including a flow passage therethrough; one or more orifices formed in the housing extending between an interior portion of the housing and an exterior portion of the housing; and the flow sleeve being shiftable from a first open position to allow fluid flow through the one or more orifices to a second position blocking the flow of fluid to the one or more orifices in response to a pressure differential between the inside of the housing and an outside of the housing.