| 摘要 |
<p>A rotary pulsar for transmitting information to the surface from down hole comprises a stator forming passages 80 through which drilling fluid flows on its way to the drill bit. Also included is a rotor that has blades 74 that are capable of imparting a varying obstruction to the flow through the stator passages 80 depending on the orientation of the rotor, so that rotation of the rotor generates an encoded pressure pulse. The rotor is located downstream of the stator. Means for imparting a torque on the rotor is provided, so that the rotor is urged to rotate to the position of least flow obstruction. The torque may be induced by the shape of the downstream face 73 of the rotor blades or by a spring.</p> |
