Downhole motor drive shaft universal joint assembly

A universal joint assembly, comprising:

• a first rotary member having a first longitudinal axis and an outer tubular portion at one end thereof concentrically disposed about said axis;
• a second rotary member having a second longitudinal axis and an inner tubular portion at one end thereof concentrically disposed about said axis, said second member being adapted to be telescopically received within said outer tubular end portion of said first member:
• bearing means for transmitting axial loads between said first and second members, said bearing means pivotally connecting said first and second members to provide limited omni-directional pivotal movement of one of said first and second members with respect to the other of said first and second members about a point of intersection of the longitudinal axes of said first and second members;
• and
• torque transfer means disposed between said outer and inner tubular end portion for transferring torque between said first and second members, said torque transfer means pivotally connecting said first and second members to provide limited omni-directional pivotal movement of one of said first and second members with respect to the other of said first and second members about a point of intersection of the longitudinal axes of said first and second members, said torque transfer means including longitudinal slots formed in one of said tubular end portions and keys extending from the other of said tubular end portions into torque transfer relation with said slots;
• said tubular end portion of said one of said members defining a chamber for reception of said tubular end portion of the other of said members, said chamber being adapted to be packed with lubricating fluid for lubricating moveable components disposed within said chamber, further including seal means engageable with said first and second members for retaining said lubricating fluid within said chamber, said seal means comprising, a ring member having an inner cylindrical surface, an opposed outer cylindrical surface and opposed annular end surfaces, one of said end surfaces being abuttingly engageable with an annular end surface of said tubular end portion of said first member, the other of said end surfaces of said ring member being engageable with retaining means secured to said first member, a first seal member disposed in said inner surface and engageable with said outer cylindrical surface of said second member in fluid sealing relating thereto, a second seal disposed in the other of said end surfaces and engageable with said retaining means in fluid sealing relation thereto;
• means for equalizing the pressure between the interior and exterior of said assembly, said pressure equalizing means including a chamber in said inner member, one end of said chamber communicating with the interior of said assembly and the other end communicating with the exterior of said assembly, and sliding seal means sealingly engaged with surfaces of said chamber, said sliding seal means being moveable in said chamber in response to a pressure differential on opposite sides thereof to a position whereat the pressure differential is minimized.

A universal joint assembly, comprising:

• a first rotary member having a first longitudinal axis and an outer tubular portion at one end thereof concentrically disposed about said axis;
• a second rotary member having a second longitudinal axis and an inner tubular portion at one end thereof concentrically disposed about said axis, said second member being adapted to be telescopically received within said outer tubular end portion of said first member;
• each said tubular end portion comprising a tubular wall defining an outer cylindrical surface and a concentric inner cylindrical surface;
• bearing means for transmitting axial loads between said first and second members, said bearing means pivotally connecting said first and second members to provide limited omni-directional pivotal movement of one of said first and second members with respect to the other of said first and second members about a point of intersection of the longitudinal axes of said first and second members, said bearing means comprising a first concave spherical seat in and centered on the longitudinal axis of one of said members, a second concave spherical seat in and centered on the longitudinal axis of the other of said members and a ball disposed between and seated on said first and second spherical seats, the centre of said ball defining said point of intersection of said first longitudinal axis of said first member and said second longitudinal axis of said second members;
• a first cylindrical seat member, said first spherical seat being formed in one end of said first seat member, said first seat member being disposed in said inner cylindrical surface of said second member in close fit relation, a concentric bore formed in said first member, a second cylindrical seat member, said second spherical seat being formed in one end of said second seat member, said second seat member being disposed in said concentric bore of said first member in close fit relation therewith;
• and
• torque transfer means disposed between said outer and inner tubular end portion for transferring torque between said first and second members, said torque transfer means pivotally connecting said first and second members to provide limited omni-directional pivotal movement of one of said first and second members with respect to the other of said first and second members about a point of intersection of the longitudinal axes of said first and second members, said torque transfer means including a plurality of equally angularly spaced longitudinal slots in said inner cylindrical surface of said outer tubular end portion of said first member, each said slot having a bottom surface and opposed side surfaces, and keys extending from the other of said tubular end portions into torque transfer relation with said slots, said keys being secured to said inner tubular end portion for pivotal movements about radial axes, each said key having a cylindrical shank portion adapted to be received in a radial bore in said inner tubular end portion and an elongated head portion extending transversely of said shank portion, each said head portion having a width which is substantially the same as that of said slots, said keys corresponding in number to the number of said slots and extending radially outwardly from said outer cylindrical surface of said inner tubular end portion of said second member, each said head portions having an arcuate surface remote from said shank portion arranged to be juxtaposed adjacent said bottom surface of an associated slot and opposed side surfaces abuttingly engageable in torque transfer relation with said opposed side surfaces of said associated slot, said head portion of each said key being longitudinally moveable in said associated slot in response to pivotal movement of said first and second members and said keys being operable to transfer torque between said first and second members;
• said tubular end portion of said first rotary member defining a chamber for reception of said tubular end portion of said second rotary members, said chamber being packed with lubricating fluid for lubricating moveable components disposed within said chamber, further including seal means engageable with said first and second members for retaining said lubricating fluid within said chamber, said seal means comprising, a ring member having an inner cylindrical surface, an opposed outer cylindrical surface and opposed annular end surfaces, one of said end surfaces being abuttingly engageable with an annular end surface of said tubular end portion of said first member, the other of said end surfaces of said ring member being engageable with retaining means secured to said first member, a first seal member disposed in said inner surface and engageable with said outer cylindrical surface of said second member in fluid sealing relation thereto, a second seal disposed in the other of said end surfaces and engageable with said retaining means in fluid sealing relation thereto;
• and
• means for equalizing the pressure between the interior and exterior of said assembly, said pressure equalizing means including a chamber in said inner member, one end of said chamber communicating with the interior of said assembly and the other end communicating with the exterior of said assembly, and sliding seal means sealingly engaged with surfaces of said chamber, said sliding seal means being moveable in said chamber in response to a pressure differential on opposite sides thereof to a position whereat the pressure differential is minimized.