Variable speed drive for progressing cavity pumps

A variable speed drive for RPM control of a progressing cavity pump comprising:

• a frame mounted stationary in relation to the pump;
• a motor means mounted on the frame;
• a driving shaft pivotally mounted on the frame, and rotatable by the motor means;
• a pivotable driven shaft essentially rotating the pump, said driven shaft aligned in parallel to the driving shaft;
• a first cone-shaped rotor fixedly mounted on the driving shaft;
• a second cone-shaped rotor, fixedly mounted on the driven shaft, and substantially identical to the first rotor, said rotors situated in inverse positions to each other;
• an elastic belt, substantially having a constant length, and stretchably placed around the first and second rotors, so that forming a first straight branch and a second straight branch, a first curved section frictionally coupled with the first rotor, and a second curved section frictionally coupled with the second rotor;
• a worm gear mechanism, including
• a screw-threaded gear shaft pivotally disposed within the frame,
• a turning means capable to rotate the gear shaft;
• a screw-threaded bushing revolvably associated with the gear shaft as a screw pair,
• a first half-shaft with an inner end fixedly coupled to said bushing, and an outer end slidely movable in relation to the frame;
• a second half-shaft with an inner end fixedly coupled to said bushing, and an outer end slidely movable in relation to the frame, the half-shafts disposed in the same plane with and perpendicularly to the gear shaft;
• a first roll revolvably mounted on the first half-shaft;
• and
• a second roll revolvably mounted on the second half-shaft;
• wherein the first branch extending below the first roll and brought into contact therewith, and, the second branch extending above the second roll and brought into contact therewith, so that said first roll capable to displace said first branch in a first direction, or alternatively said second roll capable to displace said second branch in a second direction parallel and oppositely oriented to the first direction, causing corresponding displacements Of the belt along the first direction or alternatively along the second direction, thereby changing planes of the belt's disposition, causing changes of the transmission ratio of said drive, and therefore controlling the RPM of the pump.