Rotary Machines With Teardrop-Shaped Rotors

Abstract

Rotary positive displacement machines can include a rotor having a teardrop-shaped profile that undergoes planetary motion relative to a stator having an elliptical or near-elliptical profile. In some embodiments, these rotary positive displacement machines can be used for a variety of applications including as positive displacement pumps. In some embodiments the rotor and stator are helical. In some embodiments the rotor comprises a dynamic seal. Aspects of the machine geometry can be selected to provide operational and/or durability benefits.

What is claimed is: 
     
         1 . A rotary machine comprising”
 a stator having a stator cavity; and 
 a rotor disposed within said stator cavity, 
 said rotor having a rotor helical profile, and a rotor axis, and having a rotor shape in cross-section transverse to said rotor axis along at least a portion of a length of said rotor that is a teardrop shape, 
 said stator cavity having a stator helical profile, a stator axis, and having a stator shape at any cross-section transverse to said stator axis along at least a portion of a length of said stator cavity that is an outer envelope formed when said teardrop shape undergoes planetary motion, 
 wherein said rotary machine is configured so that, in operation of said rotary machine, said rotor undergoes planetary motion relative to said stator, and 
 wherein said stator shape is an outwardly offset ellipse. 
 
     
     
         2 . The rotary machine of  claim 1  further comprising a helical dynamic rotor seal mounted on said rotor. 
     
     
         3 . The rotary machine of  claim 1  wherein said rotary machine is configured so that, in operation of said rotary machine, said rotor spins about said rotor axis and orbits about said stator axis within said stator cavity. 
     
     
         4 . The rotary machine of  claim 1  wherein said rotary machine is a multi- stage machine having a plurality of chambers between cooperating fluid-facing surfaces of said rotor and said stator. 
     
     
         5 . The rotary machine of  claim 4  wherein each of said plurality of chambers has approximately the same volume. 
     
     
         6 . The rotary machine of  claim 4  wherein said rotary machine is a pump. 
     
     
         7 . The rotary machine of  claim 4  wherein each of said plurality of chambers has a different volume.