Drive shaft assembly for downhole mud motor configured for directional drilling

A downhole mud motor for directional drilling, comprising:

• a power section consisting of a rotor and a stator;
• a driveshaft assembly threadedly connected to the power section;
• and
• a bearing assembly threadedly connected to the driveshaft assembly, wherein
• the driveshaft assembly comprises
• a cylindrical upper member, one end of the upper member being connected to the rotor and an other end of the upper member having a plurality of torque transmitting profiles;
• an elongated central member having two ends, the two ends of the central member each having a plurality of torque transmitting profiles;
• a seat retained within a central bore of the upper member, the seat having at least one curved end;
• and
• an elongated catch retained within the central member, the catch having at least one curved end and extending from a position within the central member to a position outside of the central member beyond the torque transmitting profiles of the central member;
• wherein
• the upper member transfers torque from the rotor to the central member via the torque transmitting profiles of the other end of the upper member and the torque transmitting profiles of the central member,
• the curved end of the seat contacts the curved end of the catch while maintaining a gap between the other end of the upper member and the end of the central member,
• wherein the upper member comprises an internal bore for housing the seat, and an internal shoulder configured to retain the curved end of the catch, and
• wherein the curved end of the catch includes at least two protrusions;
• the other end of the upper member includes at least two cutouts extending from the internal bore of the upper member and corresponding to the at least two protrusions on the curved end of the catch;
• and the upper member is locked to the central member by inserting the curved end of the catch into the internal bore of the upper member, the protrusions on the catch being inserted into the respective cutouts, and rotating the catch within the internal bore of the upper member.

A driveshaft assembly for a downhole motor for directional drilling, comprising:

• a cylindrical upper member, one end of the upper member being connected to a rotor of the downhole motor and an other end of the upper member having at least three torque transmitting profiles;
• an elongated central member having two ends, the two ends of the central member each having at least three torque transmitting profiles;
• a seat retained within a central bore of the upper member, the seat having at least one curved end;
• and
• an elongated catch retained within the central member, the catch having at least one curved end, a lengthwise dimension of the catch being different from a width dimension of the catch, and the catch extending from a position within the central member to a position outside of the central member beyond the torque transmitting profiles of the central member;
• wherein
• an angular displacement between the upper member and the central member is based on a radius of the curved end of the seat and a radius of the curved end of the catch,
• wherein the upper member comprises an internal bore for housing the seat, and an internal shoulder configured to retain the curved end of the catch, and
• wherein the curved end of the catch includes at least two protrusions;
• the other end of the upper member includes at least two cutouts extending from the internal bore of the upper member and corresponding to the at least two protrusions on the curved end of the catch;
• and the upper member is locked to the central member by inserting the curved end of the catch into the internal bore of the upper member, the protrusions on the catch being inserted into the respective cutouts, and rotating the catch within the internal bore of the upper member.