Screw vacuum pump
AssigneeFoundation for Advancement of International Science
InventorTadahiro Ohmi
Life of this patent
Estimating the term…
Abstract
In a screw vacuum pump 30, equal lead screws each in the range of 1 to 4 leads are added on the discharge side of male and female screw rotors (4) and (5) having a continuously changing screw gear helix angle, at a final lead angle of the male and female unequal lead screw rotors on the discharge side that continuously change in helix angle following the advance of the screw gear helix.
Claims6
A screw vacuum pump comprising a male rotor and a female rotor respectively having engagement screw gears;
- a stator receiving therein both rotors;
- a gas working chamber formed by the male rotor and the female rotor and the stator;
- and an inlet port and a discharge port for a gas provided at said stator so as to be capable of communicating with one end portion and the other end portion of said working chamber, respectively, wherein each of said male and female rotors includes a main lead screw in which a helix angle of said screw gear continuously changes following the advance of helix, and a sub lead screw in the form of an equal lead screw formed in the range of 1 to 4 leads at a final lead angle of said main lead screw on a discharge side of said male and female rotors.
A screw vacuum pump comprising a male rotor and a female rotor respectively having engagement screw gears;
- a stator receiving therein both rotors;
- a gas working chamber formed by the male rotor and the female rotor and the stator;
- and an inlet port and a discharge port for a gas provided at said stator so as to be capable of communicating with one end portion and the other end portion of said working chamber, respectively, wherein each of said male and female rotors includes a main lead screw in which a helix angle of said screw gear continuously changes following the advance of helix, and an additional lead screw provided on an inlet side of said male and female rotors, said additional lead screw being in the form of an equal lead screw formed in the range of 0.2 to 1 lead at a lead angle of said main lead screw at its end portion on said inlet side.
A screw vacuum pump comprising a male rotor and a female rotor respectively having engagement screw gears;
- a stator receiving therein both rotors;
- a gas working chamber formed by the male and the female rotors and the stator;
- and an inlet port and a discharge port for a gas provided at said stator so as to be capable of communicating with one end portion and the other end portion of said working chamber, respectively, wherein engagement of said screw gears of said male and female rotors is located outside gear engagement pitch circles determined by a distance between axes of said male and female rotors and the numbers of teeth of said male and female rotors.
A screw vacuum pump comprising a pair of male and female unequal lead screw rotors, wherein said male and female unequal lead screw rotors includes equal lead portions having a lead angle equal to an inlet-side lead angle and formed on an inlet side thereof;
- equal lead portions having a lead angle equal to a discharge-end lead angle and formed on a discharge side thereof;
- and engagement formed at a position outside gear engagement pitch circles, said circles being determined by a distance between axes of said male and female rotors and the numbers of teeth of said male and female rotors.
Dependencies are inferred from the claim text.