| 摘要 |
<p>In a down hole drilling tool a closed valve is operatively moved downwards by pressurised drilling mud pumped down the drill string, the valve when it attains its lower position being opened and being returned under the influence of a spring or other upwardly urging means acting on the valve to its upper position at which the valve is closed thereby to complete the cycle of operations. The valve is so continuously coupled to a torque member that the downward movement of the valve causes turning of the torque member in one direction, and the upward movement of the valve causes turning of the torque member in the opposite direction. A drill bit mounted on the lower end of a rotor is connected through a one-way clutch to the torque member so that during the downward movement of the valve the rotor and drill bit are rotatably driven by the torque member but are stationary during the upward movement of the valve, the drill bit thus being operatively intermittently rotated, During the upward movement of the valve the pressurised drilling mud flows through the open valve and issues from the drill bit as high pressure and volume flushing jets while the drill bit is stationary, thereby providing more effective cleaning of cuttings and chips from the bottom of the bore hole being formed by the drill bit. Aligned annular grooves are provided in the rotor and in the housing in which the rotor is mounted, ball bearings being disposed partially in each of these grooves thereby to provide an axial thrust bearing capable of transmitting high axial thrust from the housing to the rotor and hence to the drill bit. Lipped pockets are also provided in the rotor in communication with the grooves therein, with the ball bearings being disposed within these pockets during assembly and disassembly of the rotor and housing.</p> |
