Abstract: A device for limiting the flow of drilling fluid through a section of drill string is described. The device includes a cylindrical tube with holes in its periphery. Flow enters the device through an upper end of the tube and a portion of the flow exits through the lower end of the tube. In addition, some of the flow is diverted through the peripheral holes. A valve piston is supported near the lower end of the tube by a spring of approximately constant force through its range of travel. The valve piston moves axially as the flow rate through the tube changes flow rate to ensure that a substantially constant amount of flow exits through the lower end, while the excess flow is diverted from the tube through the peripheral holes. A means of damping or stopping the axial movement of the valve piston is included in the device.
Type:
Grant
Filed:
November 30, 2015
Date of Patent:
January 28, 2020
Assignee:
Dynomax Drilling Tools USA, Inc.
Inventors:
David S. Cramer, Michael J. Harvey, David D. Devlin