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Mud pressure control system

  • US 4,636,995 A
  • Filed: 08/09/1985
  • Issued: 01/13/1987
  • Est. Priority Date: 08/27/1980
  • Status: Expired due to Term
First Claim
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1. A down-hole signal transmitter for a mud-pulse telemetry system, comprising a flow constrictor defining a throttle orifice for the mud passing along a drill string, a throttling member displaceable as a whole towards and away from the throttle orifice to vary the throughflow cross-section of the throttle orifice, a turbogenerator for supplying a measuring instrument and arranged to be driven by the mud flow passing along the drill string, and control means for controlling displacement of the throttling member towards and away from the throttle orifice to modulate the mud pressure, wherein the control means is coupled to the rotor of the turbogenerator and is adapted to displace the throttling member in one direction when the electrical load of the turbogenerator is such that the torque required to drive the rotor exceeds the maximum torque available for driving the rotor, and to displace the throttling member in the opposite direction when the electrical load of the generator is such that the torque required to drive the rotor does not exceed the maximum torque available for driving the rotor.

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