| 摘要 |
A drill bit for use in an earthen annulus that contains loose particles is connected to a fluid supply source and includes a bit body having at least one journal segment and at least one fluid conduit in fluid communication with the fluid supply source. A roller cone is rotatably mounted upon the journal segment and forms at least one bearing cavity therebetween. An annular primary seal is disposed between the roller cone and the bit body and between the bearing cavity and the earthen annulus, and an annular gap is disposed between the annular primary seal and the earthen annulus. The annular gap is in fluid communication with the fluid conduit and the earthen annulus. An annular secondary seal is disposed between the annular primary seal and the earthen annulus and is capable of substantially preventing the ingress of debris from the earthen annulus to the annular primary seal. |
