Well bore data transmission apparatus

A hydromechanical signal transmitter apparatus for transmitting information signals in a flowing liquid medium by generation of pressure pulses in the medium comprising:

• a housing (2) of generally cylindrical form having an axis;
• a hydromechanical signal transmitter (5) in said housing, said transmitter comprising a stator (6) fixed within the housing and a disc shaped rotor (7) rotatable relative to the stator about said axis;
• said stator having at least one pair of liquid passage (8,9) extending through said housing for passing fluid of said liquid medium therethrough, said at least one pair of passages being axially aligned with each other and disposed on opposite sides of said disc shaped rotor (7);
• said disc shaped rotor (7) having openings (15) formed therein at positions corresponding to each of said at least one pair of passages, said rotor being rotatable between a passing position wherein fluid in said passages (8,9) passes through a corresponding opening (15) aligned therewith and a throttling position wherein said rotor is moved to a position such that flow of fluid through said passages is obstructed by a closed portion of said disc shaped rotor;
• drive shaft means (16) connected to said rotor for rotating the rotor between said passing position and said throttling position, said drive shaft means having radial stop faces (25,26) which abut against a stop means (24) integral with said housing to stop rotation of said rotor at limit positions corresponding to said passing and throttling positions, respectively;
• and
• reversible motor means for driving said shaft means in accordance with information signals provided thereto to control movement of said rotor of said hydromechanical signal transmitter (5) between said limit positions to generate pressure pulses in said fluid corresponding to said signals.