| 摘要 |
<p>A roller cone drill bit includes at least one roller cone (18) rotatably mounted on a bit body. The bit body defines a lubricant reservoir (14) adapted to supply lubricant to bearings (24, 58, 60) on which the roller cones (18) rotate about the bit body. The bit includes a sensor (62) adapted to detect drilling fluid contamination of the lubricant. The bit includes a processor/transmitter (40) coupled to the sensor (62) and adapted to communicate signals indicating the detection of contamination. The sensor (62) may be a capacitance sensor, a resistance sensor, or a pH sensor. A further embodiment describes measuring a lubricant pressure within a drill bit by a sensor (P2, fig 4) and a pressure in a drilling fluid outside the bit by a sensor (P1, fig 4). A pressure compensator piston (41, fig 4) is used to maintain a selected differential pressure between the lubricant and the fluid outside of the bit.</p> |
