The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 10, 2001
Filed:
Nov. 18, 1999
Hirotaka Kameya, Tsuchiura, JP;
Shigekazu Nozawa, Shimizu, JP;
Masayuki Urashin, Shimizu, JP;
Takeshi Hida, Shimizu, JP;
Masakazu Aoki, Shimizu, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A screw rotor for use in screw compressors and screw vacuum pumps comprises a pair of rotors including a male rotor and a female rotor. These rotors have helical lobes in an axial direction and mesh with each other to form a compression chamber. Depending upon a lobe configuration of the rotors, suction pressure and discharge pressure, a negative torque for self-rotation as well as a positive torque opposing to rotation due to a compression action is generated on the female rotor in operation. This phenomenon generates when a value obtained by integrating a torque acting on the female rotor over an entire cross section in an axial direction of the rotors becomes negative. When the negative torque is generated, noises due to tooth separating vibration is caused. Then, a lobe profile is defined such that a magnitude of the negative torque is smaller than that of the positive torque in respective cross sections of the female rotor. That is, a relationship between a radius of a point of contact on a leading surface side of the female rotor and a radius of a point of contact on a trailing surface side or curvatures of the rotors are such that the negative torque is not generated on the lobe profile.