Roots vacuum pump
First Claim
1. A Roots vacuum pump comprising a casing having an inlet port and an outlet port both formed therein and a pair of three-lobed rotors provided in the casing to be rotatable so that the inlet and outlet ports are prevented from communicating with each other, whereupon air is sucked through the inlet port and the sucked air is discharged through the outlet port, wherein the inlet port is located at a position n spaced by a positive displacement angle of 120°
- in one direction from a center of each rotational axis relative to an imaginary line m connecting the centers of the rotational axes of the respective rotors, and the outlet port is located at a position o spaced by a positive displacement angle of 120°
in a direction opposite the direction of the inlet port from the center of each rotational axis relative to the imaginary line m, wherein outside air or cooling air feed port is provided at a position t on a peripheral wall of the casing obtained by returning by 90°
from the position o to the inlet port side so that two closed spaces are defined by adjacent lobes of the rotors and an inner peripheral wall surface of the casing at the inlet and outlet port sides immediately after suction of air respectively, wherein the casing has a plurality of discharge grooves which are formed in a region of the inner peripheral wall surface so as to communicate with the outlet port, said region ranging from the position o to a position u obtained by returning by 45°
from the position o to the inlet port side, the discharge grooves having a total volume ranging from 2% to 5% of a volume of one of the closed spaces.
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Accused Products
Abstract
In a Roots vacuum pump, an inlet port is located at a position n spaced by a positive displacement angle of 120° in one direction from a center of each rotational axis relative to an imaginary line m connecting rotor axes. An outlet port is located at a position o opposite to the inlet port relative to the line. An air feed port is formed at a position t on a casing wall obtained by returning by 90° from the position o to the inlet port side so that two closed spaces are defined by adjacent rotor lobes and a casing inner wall at both port sides immediately after air suction respectively. The casing has discharge grooves in an area of the inner wall so as to communicate with the outlet port. The area ranges from the position o to a position u obtained by returning by 45° from the position o to the inlet port side. The discharge grooves have a total volume ranging from 2% to 5% of a volume of one of the closed spaces.
32 Citations
1 Claim
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1. A Roots vacuum pump comprising a casing having an inlet port and an outlet port both formed therein and a pair of three-lobed rotors provided in the casing to be rotatable so that the inlet and outlet ports are prevented from communicating with each other, whereupon air is sucked through the inlet port and the sucked air is discharged through the outlet port, wherein the inlet port is located at a position n spaced by a positive displacement angle of 120°
- in one direction from a center of each rotational axis relative to an imaginary line m connecting the centers of the rotational axes of the respective rotors, and the outlet port is located at a position o spaced by a positive displacement angle of 120°
in a direction opposite the direction of the inlet port from the center of each rotational axis relative to the imaginary line m, wherein outside air or cooling air feed port is provided at a position t on a peripheral wall of the casing obtained by returning by 90°
from the position o to the inlet port side so that two closed spaces are defined by adjacent lobes of the rotors and an inner peripheral wall surface of the casing at the inlet and outlet port sides immediately after suction of air respectively, wherein the casing has a plurality of discharge grooves which are formed in a region of the inner peripheral wall surface so as to communicate with the outlet port, said region ranging from the position o to a position u obtained by returning by 45°
from the position o to the inlet port side, the discharge grooves having a total volume ranging from 2% to 5% of a volume of one of the closed spaces.
- in one direction from a center of each rotational axis relative to an imaginary line m connecting the centers of the rotational axes of the respective rotors, and the outlet port is located at a position o spaced by a positive displacement angle of 120°
Specification
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- Resources
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Current AssigneeAnlet Co., Ltd.
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Original AssigneeAnlet Co., Ltd.
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InventorsIto, Yoshinobu, Yokoi, Yasuna
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Primary Examiner(s)Trieu; Theresa
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Application NumberUS11/546,221Time in Patent Office238 DaysField of Search418/9, 418/15, 418/78, 418/180, 4182061-2065US Class Current418/206.4CPC Class CodesF04C 15/0049 Equalization of pressure pu...F04C 18/126 with radially from the roto...
