An external axis rotary piston compressor comprising in combination:
- a housing having a first and second side part, and at least two overlapping, parallel-axis, cylindrical inner chambers, each having a respective shaft passing therethrough, said housing further being provided with an outlet passage, from said inner chambers, for conveyed working gas;
- a cylindrical working rotor arranged on one of said shafts, which is associated with a drive shaft journalled in said second side part, with said outlet passage in said housing essentially extending tangential to the direction of movement of said working rotor;
- the body of said working rotor being a hollow cylinder mounted in said first side part and rigidly and coaxially connected with said drive shaft, said hollow cylinder being provided with a hollow shutoff projection which projects radially outwardly therefrom, said hollow cylinder being further provided with a first port which communicates the hollow interior of said hollow cylinder with the hollow interior of said shutoff projection;
- said working rotor forming an annular working chamber with that portion of said housing which surrounds it, said working chamber, when viewed in the direction of rotation of said working rotor, including a suction chamber behind said shutoff projection, with said shutoff projection being provided on its rear side with an inlet opening, into said suction chamber, for working gas;
- a cylindrical shutoff rotor arranged on the other of said shafts, which turns in the opposite direction to the one of said shafts, said shutoff rotor running along the associated portion of said housing, and riding on said working rotor;
- said shutoff rotor being provided with a recess for passage of said shutoff projection therethrough without contacting said shutoff rotor;
- and
- a stationary sleeve fixed to said first side part and arranged in said hollow cylinder in such a way as to be sealingly surrounded thereby, said sleeve being provided with a second port which is adapted to coincide with said first port of said hollow cylinder when the latter rotates, said sleeve having an inner chamber which forms an inlet passage for drawn-in working gas;
- said first and second side parts of said housing being respectively provided with recesses for receiving the axial ends of said shutoff rotor in such a way that they do not contact the radial cylindrical surface of said shutoff rotor, but only form an extremely narrow gap relative thereto;
- an intermediate layer, of a material having low friction properties, placed and sealingly filling the gap between said hollow cylinder and said sleeve;
- said shutoff projection being made of aluminum, said hollow cylinder being made of steel, and said shutoff projection being counterbalanced by removal of material from said hollow cylinder to form said first port therein;
- said second side part being integral with said housing, and said cylindrical inner chamber, as well as said recesses in said side parts, being circular milled, that side of said shutoff projection remote from said inlet opening thereof extending at an angle which is 20.degree. to 30.degree. from the radial direction;
- a connecting passage in that portion of said housing which is adjacent said outlet passage and which is provided with the inner chamber accommodating said shutoff rotor, said connecting passage communicating this inner chamber with said outlet passage, and having an axial length of approximately 80 to 90% of the length of said shutoff rotor;
- said connecting passage widening in the direction toward said outlet passage, said housing being rounded off at the transition from said inner chambers into said outlet passage.