Patent ID: 7828535

Claim:
A self sealing twin rotor tapered screw pump apparatus ( 10 ) comprising: a first tapered rotor ( 22 ) having a large end ( 32 ) and a small end ( 34 ), said first tapered rotor ( 22 ) further including a tapered core ( 30 ) and at least one spiral flight ( 36 ) surrounding said core ( 30 ) having a width that increases as said spiral flight ( 36 ) progresses from said larger end ( 32 ) to said smaller end ( 34 ); a second tapered rotor ( 24 ) also having a large end ( 52 ) and a small end ( 54 ), said second tapered rotor ( 24 ) further including a tapered core ( 50 ) and at least one spiral flight ( 56 ) surrounding said tapered core ( 50 ) having a width that increases as said spiral flight ( 56 ) progresses from said larger end ( 52 ) to said smaller end ( 54 ), and wherein said spiral flight ( 56 ) of said second tapered rotor ( 24 ) rotates in a direction opposite from the direction of rotation of the spiral flight ( 36 ) on said first tapered rotor ( 22 ); a pump housing ( 12 ) having two adjacent tapered cavities ( 14 , 18 ) therein for receiving said first and second tapered rotors ( 22 , 24 ) so that said tapered rotors ( 22 , 24 ) engage each other, said pump housing ( 12 ) further including a high pressure port ( 28 ) located adjacent said large ends ( 33 , 52 ) of said tapered rotors ( 22 , 24 ) and a low pressure port ( 26 ) located adjacent said small ends ( 34 , 54 ) of said tapered rotors ( 22 , 24 ), wherein rotation of one of said tapered rotors ( 22 , 24 ) causes fluid introduced into said low pressure side through port ( 26 ) to be pumped into said high pressure side and further wherein said fluid in said high pressure side pushes against the large ends ( 32 , 52 ) of said tapered rotors ( 22 , 24 ) forcing said tapered rotors ( 22 , 24 ) into sealing relationship with one or more walls ( 16 , 20 ) of said tapered cavities ( 14 , 18 ).