Patent ID: 7074026

Claim:
A vacuum pump comprising: an inlet port and first and second exhaust ports through which gas from an enclosure connectable to the inlet port can be pumped to said exhaust ports; a first end, a second end, a third end, and a fourth end of a pump chamber, said first exhaust port is located adjacent said first end, said second exhaust port is located adjacent said second end, said inlet port is located adjacent said third end; a first and second pair of rotors, said first pair of rotors being mounted on a first shaft extending between said first end and said second end of said pump chamber, said first pair of rotors being spaced apart by a first center shaft between said rotors, said second pair of rotors being mounted on a second shaft extending between said first end and said second end of said chamber, said second pair of rotors being spaced apart by a second center shaft between said rotors; said rotors each comprise a set of screw threads; and said first center shaft comprises a first lobe extending from said shaft and a first channel, and said second center shaft comprises a second lobe extending from said shaft and a second channel, wherein said first lobe matingly engages said second channel and said second lobe engages said first channel during rotation of said rotors.