Drive shaft assembly for downhole drilling motors

A drive shaft assembly for a downhole drilling motor, comprising:

• a shaft extending along a first longitudinal axis of rotation, and having a first end portion and a second end portion, each end portion including:
• a circular base surface with a center on the first longitudinal axis of rotation and having a first and second prongs extending away from the base surface in the direction of the first longitudinal axis of rotation, wherein each of the first and second prongs has cylindrical sector shaped body, and
• a cylindrical side wall having a plurality of ball bearings held in a plurality of circumferentially spaced pockets;
• and
• a first housing extending along a second longitudinal axis of rotation, the first housing including:
• a first end including a first cavity for operatively receiving the first end portion of the shaft, the first cavity being separated from a second cavity located at a second end of the first housing by an internal wall having an internal wall surface, the first cavity including:
• an inner side wall including a plurality of cylindrical grooves, each of which mating with one of the plurality of ball bearings on the first end portion of the shaft to transfer torque between the shaft and the first housing with or without any angular offset between the first and second longitudinal axes of rotation, and
• a first chamber and a second chamber formed in the internal wall surface which are configured to receive and retain the first prong and the second prong to transfer torque and thrust loads between the first end portion of the shaft and the first housing while the circular base surface is supported on the internal wall surface;
• and
• a second housing, extending along a third longitudinal axis of rotation, having a first end and a second end, the first end of the second housing having a first cavity for operatively receiving the second end portion of the shaft.