| 摘要 |
<p>A system to maintain a desired pressure on a seal 201 comprising a motor actuated piston 206. Seal 201seals between an inside and outside environment and is acted on by pressure from the piston. Motor 207 actuates the piston along an axial path. Differential pressure sensor 204 measures fluid pressure between the inside and outside environments. Electronic feedback control system 205 is connected to the motor and interfaces with the pressure sensor to maintain pressure on the seal from the piston. There may be two pressure sensors, one detecting the outside environment mud pressure in the wellbore and a second detecting oil pressure in the inside environment. The seal may be a rotating seal. The pressure sensors may be absolute pressure sensors. A further independent claim concerns a hydraulic system with an electronically controlled valve used with a feedback control system to maintain a pressure on a seal.</p> |
