Abstract: A process to control the delivery of a single screw compressor comprising a screw meshing with two pinion wheels and rotatable inside a casing. A channel with obturating means is provided to connect the high pressure orifice pertaining to a one pinion-wheel and the low pressure orifice. Auxiliary orifices are arranged to connect the various zones of the casing exposed to pressure with the low pressure orifice, said auxiliary orifices being provided with obturating devices. Said orifices are sequentially opened to diminish the delivery, starting from the orifice located near the low pressure orifice. First, the orifices pertaining to the first pinion wheel are sequentially opened. Then, the channel connecting the high pressure orifice of the first pinion and the low pressure orifice is opened. Then, the auxiliary orifices pertaining to the second pinion are sequentially opened.

Abstract: A process to supercharge and control a compressor comprising a single screw co-operating with at least two pinions in order to constitute as many partial compressors as there are pinions, such partial compressors operating in parallel and one of them at least being provided with a delivery control device, wherein the supercharging flow is injected into only one of the partial compressors and the delivery of the compressor is controlled from maximal delivery by reducing at first the deliveries of those partial compressors into which the supercharging flow is not injected.

Abstract: A tool having only an end cutting-edge carries out a first movement of penetration into a screw blank so as to produce a groove having flanks substantially parallel to the pinion axis. The tool-holder is angularly displaced with respect to the spindle which carries the screw blank. A second movement of tool penetration takes place while the relative displacement is progressively reduced in order to obtain an inclined flank which produces a V-shaped profile. The screw is intended to form part of a compression and expansion machine and to cooperate with at least one pinion having V-form teeth.

Abstract: A compressor or expansion machine for fluids comprises a rotor, a casing at least partially surrounding the rotor and a pinion which is rotatable about an axis which is not parallel to the rotor axis. The rotor is provided with helical threads having crests which are disposed on a surface of revolution about the rotor axis and the pinion has teeth which engage between two adjacent threads of the rotor to form a compression or expansion chamber in conjunction with the casing, the flanks of the pinion teeth comprising at least three skewed surfaces which intersect in at least two edges.

Abstract: A tool having only an end cutting-edge carries out a first movement of penetration into a screw blank so as to produce a groove having flanks substantially parallel to the pinion axis. The tool-holder is angularly displaced with respect to the spindle which carries the screw blank. A second movement of tool penetration takes place while the relative displacement is progressively reduced in order to obtain an inclined flank which produces a V-shaped profile. The screw is intended to form part of a compression and expansion machine and to cooperate with at least one pinion having V-form teeth.

Abstract: In a double-acting rotary compressor having two compression spaces each constituted by at least one variable-volume compression chamber which is put into communication first with the suction enclosure and then with the discharge enclosure, the power consumption at low delivery is reduced by causing the two compression spaces to discharge in parallel into a common duct in the vicinity of maximum delivery and connecting the spaces in series for deliveries below a predetermined value by joining the outlet of the first space to the second space at a point at which the compression chamber is already isolated from the suction enclosure.