Articulated coupling for use with a downhole drilling apparatus

A downhole drilling apparatus comprising:

• a drill string;
• a downhole motor connected to the lower end of the drill string, the downhole motor including a rotor;
• an articulated coupling having first and second ends, first stub shaft at the first end a second stub shaft at the second end and an intermediate member having first and second ends, the intermediate member connected to the first stub shaft at the first end and the second stub shaft at the second end thereof, the intermediate member including at least one torque transmitting portion and a separate thrust transmitting portion;
• the torque transmitting portion transmitting substantially all torque between the first and second stub shafts and the thrust transmitting portion transmitting substantially all thrust between the first and second stub shafts;
• wherein the first stub shaft of the articulated coupling is attached to the rotor;
• and
• a drill bit drive shaft connected to the second stub shaft of the articulated coupling so as to rotate with the second stub shaft;
• whereby the articulated coupling permits an angular deviation of the first stub shaft relative to the second stub shaft to accommodate directional drilling.

A directional drilling drive train for use in a downhole drilling apparatus, the drive train comprising:

• a downhole motor having a rotor;
• a first stub shaft having first and second longitudinal ends, the first stub shaft being secured at the first longitudinal end thereof to the rotor for movement therewith;
• an intermediate member having first and second longitudinal ends, the first longitudinal end of the intermediate member being secured to the second longitudinal end of the first stub shaft for movement therewith, the first stub shaft thereby connecting the rotor to the intermediate member;
• a second stub shaft having first and second longitudinal ends, the first longitudinal end of the second stub shaft being connected to the second longitudinal end of the intermediate member for movement therewith;
• a drill bit drive shaft, the drill bit drive shaft being mounted for rotation about a predetermined axis and being operatively connected to the drill bit of the downhole drilling assembly for driving the drill bit, the drill bit drive shaft having first and second longitudinal ends, the first longitudinal end of the drill bit drive shaft being secured for movement with the second stub shaft so as to rotate therewith and such that the second stub shaft connects the intermediate member to the drill bit drive shaft;
• wherein the intermediate member includes at least two distinct portions which are movable with respect to one another, one portion transmitting substantially all torque between the first and second stub shafts and another portion transmitting substantially all thrust between the first and second stub shafts.

A directional drilling drive train for driving a downhole drill bit drive shaft about a single axis, the drive train comprising:

• a housing structure;
• a downhole motor having a rotor;
• a drill bit drive shaft mounted within the housing for rotation about a predetermined axis, the drill bit drive shaft having first and second longitudinal ends, the second longitudinal end being operatively connected to a drill bit for causing rotation of the drill bit about a predetermined axis;
• an articulated coupling having first and second longitudinal ends, the first longitudinal end of the articulated coupling being connected to the rotor and the second longitudinal end of the articulated coupling being connected to the first end of the drill bit drive shaft, the articulated coupling comprising a first stub shaft having first and second longitudinal ends, a second stub shaft having first and second longitudinal ends and an intermediate member having first and second longitudinal ends, the second longitudinal end of the first stub shaft being connected to the first longitudinal end of the intermediate member and the first longitudinal end of the second stub shaft being connected to the second longitudinal end of the intermediate member;
• and
• wherein the connection between the first stub shaft and the second stub shaft is provided by the intermediate member;
• and the intermediate member includes a torque transmitting portion for transmitting substantially all torque between the first and second stub shafts and a thrust transmitting portion for transmitting substantially all thrust between the first and second stub shafts.

A progressive cavity drive train for causing rotation of a drill bit drive shaft about a single axis, the progressive cavity drive train comprising:

• a housing structure;
• a stator, the stator having a longitudinal axis;
• a rotor having a true center, the rotor being located within the stator;
• the stator and the rotor each having coacting helical lobes which are in contact with one another at any transverse section, the stator having one more helical lobe than the rotor such that a plurality of cavities are defined between the rotor and the stator, and the rotor being adapted to rotate within the stator such that the true center of the rotor orbits the axis of the stator, the orbit having a predetermined radius and the orbit causing a progression of cavities in the direction of the axis of the stator;
• a first stub shaft having a longitudinal axis and first and second longitudinal ends, the first end of the first stub shaft being connected to and movable with the rotor;
• an intermediate member, the intermediate member having first and second longitudinal ends, the first end of the intermediate member being connected to the second end of the first stub shaft;
• a second stub shaft having a longitudinal axis which is substantially colinear with the axis of the stator and first and second longitudinal ends, the second stub shaft being rotatably mounted about its longitudinal axis within the housing structure, the second end of the second stub shaft being operatively connected to the drill bit drive shaft for rotating the drill bit drive shaft about a predetermined axis, the first end of the second stub shaft being connected to the second end of the intermediate member;
• and
• the intermediate member comprising a torque transmitting portion for transmitting torque between the first and second stub shafts and a thrust transmitting portion for transmitting thrust between the first and second stub shafts.