Twin screw rotor device

A screw rotor device for positive displacement of a working fluid, comprising:

• a housing having an inlet port at a first end and an outlet port at a second end and a pair of cylindrical bores extending therebetween;
• a first rotor rotatably mounted about a first axis between said first end and said second end of said housing, said first rotor having at least one helical thread with a first helix angle and a first cross-sectional shape in a plane perpendicular to said first axis;
• a second rotor rotatably mounted about a second axis between said first end and said second end of said housing, said second rotor having at least one helical thread with a second helix angle opposite from said first helix angle and a second cross-sectional shape in a plane perpendicular to said second axis;
• and
• wherein said helical threads of said first rotor and said second rotor intermesh in a counter-rotating manner, wherein said first rotor has an identical number of helical threads as said second rotor and wherein said first rotor and said second rotor have a length approximately equal to a single pitch of said helical threads, said helical threads having a buttress thread shape in a lengthwise cross-section of said first rotor and said second rotor in a plane extending between said first axis and said second axis, wherein said buttress thread shape is comprised of parallel straight diagonal lines and a pair of opposing concave lines.

A screw rotor device for positive displacement of a working fluid, comprising:

• a housing having an inlet port at a first end and an outlet port at a second end and a pair of cylindrical bores extending therebetween;
• a pair of intermeshing rotors rotatably mounted about a respective pair of axes between said first end and said second end of said housing, wherein each one of said pair of rotors has an identical number of helical threads and has a length less than approximately a single pitch of said helical threads, said helical threads having a buttress thread shape in a lengthwise cross-section of said pair of rotors in a plane extending between said pair of axes, wherein said buttress thread shape is comprised of parallel straight diagonal lines, a pair of opposing concave lines, a first pair of straight lines substantially parallel to said pair of axes and located between said parallel straight diagonal lines and said opposing concave lines, and a second pair of straight lines substantially parallel to and offset from said first pair of straight lines, wherein said second pair of straight lines are substantially the same length as said first pair of straight lines, and said parallel straight diagonal lines are more than three times as long as said first and second pair of straight lines combined, and wherein each one of said pair of rotors has a concave/convex cross-sectional shape in a plane perpendicular to said pair of axes.