Patent ID: 9476263
Filing Date: 2016-10-25
CPC Classification: E21B

Claim Text:
1. A drilling apparatus for drilling a borehole in a subterranean formation, the drilling apparatus comprising: a body having a central axis, an upper end, a lower end, a central channel extending axially from the upper end, and a plurality of circumferentially-spaced fluid channels extending axially from the upper end and radially spaced from the central channel, wherein the central channel is configured to flow drilling fluid through the body; a plurality of pistons housed in the body, wherein each fluid channel in the body extends to one of the piston and is configured to flow drilling fluid to the corresponding piston, wherein each piston is configured to move radially outward relative to the body in response to drilling fluid supplied by the corresponding fluid channel, and wherein each piston has a formation facing surface including a plurality of cutting elements configured to engage the formation; a fluid-metering assembly configured to selectively meter the flow of drilling fluid into the fluid channels, wherein the fluid-metering assembly includes an upper component and a lower component; wherein the upper component includes a central through bore; wherein the lower component includes a central through bore and a plurality of circumferentially-spaced fluid inlets disposed about the central through bore of the lower component, wherein the central through bore of the lower component is in fluid communication with the central through bore of the upper component and the central channel of the body, and wherein the each fluid inlet of the lower component is in fluid communication with one of the fluid channels of the body; wherein the upper component is configured to move relative to the lower component to control the distribution of drilling fluid between the central through bore of the lower component and the fluid inlets of the lower component.