Multi-stage screw compressor interconnected via communication channel in common end plate

Claim 1

Screw rotor machine for an elastic working fluid comprising: casing means enclosing at least two working spaces, each generally comprising two intersecting bores with parallel axes and provided with barrel walls, with low pressure and high pressure end walls perpendicular to said axes, and with low pressure and high pressure ports disposed in said walls; a pair of intermeshing rotors respectively disposed in each working space, each rotor provided with helical lands and intervening grooves having a wrap angle of less than 360°, each pair of intermeshing rotors comprising one rotor of male rotor type and one rotor of female rotor type, said rotors each including bearings mounted thereto; and a transmission chamber containing a power transmission provided with a power shaft extending externally of said casing means, one rotor of each stage being further interconnected by said power transmission disposed in said transmission chamber; the improvement wherein the casing means comprises: means defining at least two barrels immediately adjacent each other and respectively enclosing at least the major portions of said at least two working spaces in parallel side by side, said at least two barrels being rigidly coupled together at least at portions along the length thereof in the axial direction of said working spaces; and an end plate member directly connected to said means defining at least two barrels, said end plate member having: one common plane surface defining an end wall of each of said working spaces; means for removably connecting said end plate member to an end of each of said barrels of said means defining at least two barrels so that said common plane surface defines said end walls of said barrels; means for removably receiving said bearings for all the rotors; means for enclosing said transmission chamber; and channel means in said end plate member which form at least portions of a communication channel between said at least two working spaces, said channel means having at least two ports disposed in said common plane surface.