A gear wheel for gear pumps/motors including a plurality of asymmetrical teeth, each tooth including a driving side with a convex shape and mating with a corresponding convex side of a counter-wheel and a discharge side defined, in most of its length, as a cavity of a convex profile. The discharge side is configured so that the radius passing through a tip of the teeth is substantially at least tangent to the discharge side, or intersects the discharge side.

The invention relates to a rotor pair for a compressor block of a screw machine, wherein a rotor pair comprises a secondary rotor that rotates about a first axis and a main rotor that rotates about a second axis, wherein the number of teeth of the main rotor is 3 and the number of teeth f the secondary rotor is 4. The relative profile depth of the secondary rotor is at least 0.5, preferably at least 0.515, and at most 0.65, preferably at most 0.595. rk1 is an addendum circle radius drawn around the outer circumference of the secondary rotor and rf1 is a dedendum circle radius starting at the profile base of the secondary rotor, wherein the ratio of the axis distance of the first axis from the second axis and the addendum circle radius rk1 is at least 1.636, and at most 1.8, preferably at most 1.733.

Disclosed are rotary positive displacement machines capable of acting as an engine and as a pump, serving to improve the profile of working members of helical rotary engines, compressors and pumps. An actuator is comprised of a pair of rotors having engaged helical teeth. The rotors are disposed in chambers which encircle both. The working areas of the profiles of the teeth in an engaged pair are delineated in cross-section by portions of a cycloidal curve for one rotor and by arcs of circumferences which are eccentrically offset from the axis of the second rotor. Such a profile of teeth produces an eccentrically cycloidal engagement capable to work efficiently at very high rotor rotation speeds. The presence of power contact and low sensitivity to gearwheel skews allow for working with nonhomogeneous media, including those containing solid inclusions.

The invention provides a rotary device comprising a first rotor rotatable about a first axis and having at its periphery a recess bounded by a curved surface, and a second rotor counter-rotatable to said first rotor about a second axis, parallel to said first axis, and having a radial lobe bounded by a curved surface, the first and second rotors being coupled for intermeshing rotation, wherein the first and second rotors of each section intermesh in such a manner that on rotation thereof, a transient chamber of variable volume is defined, the transient chamber having a progressively increasing or decreasing volume between the recess and lobe surfaces, the transient chamber being at least in part defined by the surfaces of the lobe and the recess; the ratio of the maximum radius of the lobe rotor and the maximum radius of the recess rotor being greater than 1.

The present invention relates to a rotor for a vacuum pump 150 having a roots pumping mechanism, the rotor comprising at least two hollow lobes 160, 162, 164, 166, each lobe having an outer wall 208 which defines a lobe profile, a hollow cavity 210 generally inward of the outer wall, and at least one strengthening rib 226 located in the cavity to resist stress on the lobes generated during rotation.

The invention relates to a bi-helical toothed wheel (1) with non-encapsulating profile (4) for hydraulic gear apparatuses (2), of the type bound to a support shaft (5) to form a driving or driven wheel of said hydraulic apparatus and comprising a plurality of teeth (6) extended with variable helix angle with continuous function in the longitudinal direction, wherein the teeth profile (4) keeps a shape continuity in each cross section thereof. More particularly, each tooth of the toothed wheel is longitudinally split in three zones: initial (A), central (B) and terminal (C) zones, and the central zone (B) has a variable helix angle, while the initial (A) and terminal (c) zones have a constant helix angle. The invention allows to manufacture contra-rotating rotors, having a non-encapsulating profile and a helix shape such as to suppress the angular point at the center of the rotors themselves and therefore all the problems related to their machining.

A rotary device includes a first rotor rotatable about a first axis and having at its periphery a recess bounded by a curved surface, and a second rotor counter-rotatable to the first rotor about a second axis, parallel to the first axis, and having a radial lobe bounded by a curved surface, the first and second rotors being coupled for intermeshing rotation, wherein the first and second rotors of each section intermesh in such a manner that on rotation thereof, a transient chamber of variable volume is defined, the transient chamber having a progressively increasing or decreasing volume between the recess and lobe surfaces, the transient chamber being at least in part defined by the surfaces of the lobe and the recess; the ratio of the maximum radius of the lobe rotor and the maximum radius of the recess rotor being greater than 1.

A reduced noise screw expander is described, which comprises a main rotor and a gate rotor each having an N profile. The rotors are designed so that the torque on the gate rotor caused by pressure forces is in the same direction as the torque on the gate rotor caused by frictional drag forces. A method of designing a screw machine exhibiting reduced noise is also described. The screw machine has two or more rotors having an N profile, and the method involves determining a ratio r/r.sub.1, where r is the main rotor addendum and r.sub.1 is the radius of the rack round side, and ensuring that this ratio is greater than 1.1 where the screw machine is to be a screw compressor or less than or equal to 1.1 where the screw machine is to be a screw expander.

The invention relates to a rotary piston engine (2) which operates as a pump, condenser or motor for a liquid or gaseous medium. The rotary piston engine (2) has a first gear (4) having a first central axis (I), a second gear (6) arranged opposite the first gear (4) and having a second central axis (II), and a drive shaft (8) having a third central axis (III) and a sliding plane (10, 12) fixedly connected to the drive shaft (8). The first central axis (I) and the second central axis (II) enclose an angle (3) which is not equal to 180. The third central axis (III) and at least one central axis (I, II) from the group comprising the first central axis (I) and second central axis (II) enclose an angle (1, 2) which is not equal to 0 or 90. The sliding plane (10, 12) and the central axis (I, II) are perpendicular to each other. The first gear (4) has a first end face (14) having a first has toothing (16) that h at least one first tooth (18), and the second gear (6) has a second end face (20) having a second toothing (22) that has at least one second tooth (24), wherein a first number of first teeth and a second number of second teeth differ from each other. The first tooth (18) and the second tooth (24) engage with each other in such a way that a working chamber (26) is formed by means of a meshing of the teeth (18, 24). A volume formed by means of the at least one working chamber (26) is changed by the meshing of the teeth (18, 24). The at least one working chamber (26) is delimited by a conically shaped inner wall (30) of a housing (28). The at least one working chamber (26) can be connected to a supply flow (40) and an outlet flow (42) for the medium. According to the invention, a component (4, 6) from the group comprising the first gear (4) and second gear (6) is coupled to the housing (28) such that a rotation of the drive shaft (8) causes only the components (4, 6) to tumble. The respective other components (4, 6) from the group comprising the first gear (4) and second gear (6) is coupled to the sliding plane (10, 12) such that the respective other component (4, 6) rotates and tumbles by means of a rotation of the drive shaft (8).

A motor includes a shaft rotatable about an axis, an engaged component engaged by the shaft, a sleeve fixed to the shaft to rotate therewith, and a seal at least partly circumscribing the shaft. The shaft includes an engagement region presenting a substantially variable outer shaft surface that at least in part engages the engaged component. The sleeve includes a first section that at least partly circumscribes and engages the engagement region of the shaft. The first section of the sleeve presents an outer seal-engaging surface and an outer bearing-engaging surface. The seal and the bearing each at least partly circumscribe the engagement region of the shaft and the first section of the sleeve to engage the seal-engaging surface and the bearing-engaging surfaces, respectively, of the sleeve.