Abstract: A bottom hole assembly for a drill string has a mud motor and a mandrel. The motor has a rotor driven by drilling fluid flow, and the rotor defines a bore for passage of fluid flow and/or conductors. The mandrel has a bore for passage of the conductors and/or fluid flow, and rotation of the mandrel rotates a drill bit. A shaft and universal joints transfer the drive of the rotor to the mandrel. To pass the conductors from a sonde uphole of the motor to electronics disposed with the mandrel and/or to conduct fluid flow, inner beams dispose in a bore of the shaft to seal at the ends of the shaft coupled to the first and second universal joints. Each beam has an internal passage for the conductors and/or fluid flow. One of the universal joints and inner beams compensate for eccentricity in motion of the rotor, while the other second universal joint and inner beam compensate for a bend in the downhole assembly.

Abstract: A bottom hole assembly for a drill string has a mud motor and a mandrel. The motor has a rotor driven by drilling fluid flow, and the rotor defines a bore for passage of fluid flow and/or conductors. The mandrel has a bore for passage of the conductors and/or fluid flow, and rotation of the mandrel rotates a drill bit. A shaft and universal joints transfer the drive of the rotor to the mandrel. To pass the conductors from a sonde uphole of the motor to electronics disposed with the mandrel and/or to conduct fluid flow, inner beams dispose in a bore of the shaft to seal at the ends of the shaft coupled to the first and second universal joints. Each beam has an internal passage for the conductors and/or fluid flow. One of the universal joints and inner beams compensate for eccentricity in motion of the rotor, while the other second universal joint and inner beam compensate for a bend in the downhole assembly.

Abstract: A driveshaft assembly includes a driveshaft with a pair of universal joints disposed at each end of the driveshaft. Each of the universal joints provides torque transfer from the driveshaft to an adapter disposed to driveshaft using a plurality of elliptical projections that mate with interior grooves of the adapter. Stress concentration on the projections may be reduced in some embodiments by providing a variable radius fillet around each of the projections at the intersection of the projection with the driveshaft.

Abstract: A driveshaft assembly includes a driveshaft with a pair of constant velocity joints disposed at each end of the driveshaft. Each of the constant velocity joints provides torque transfer from the driveshaft to an adapter disposed to driveshaft using a plurality of elliptical projections that mate with interior grooves of the adapter. Stress concentration on the projections may be reduced in some embodiments by providing a variable radius fillet around each of the projections at the intersection of the projection with the driveshaft.