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:
Mar. 06, 1979
Filed:
Apr. 11, 1977
Williams G Patterson, Palo Alto, CA (US);
Other;
Abstract
A high vacuum turbomolecular pump is described incorporating a drive system which significantly reduces the amount of heat build-up therein. The pump includes an outer casing having an upper open end adapted to be communicated hermetically with an isolated environment to be pumped, and an exhaust opening at its lower end. A plurality of vertically spaced stator blade wheels are positioned within the casing intermediate the inlet and exhaust openings, and a rotor is mounted within the casing on a spindle for rotation therewith on a generally vertical axis. The rotor is provided with a plurality of axially spaced rotor blade wheels interleaved with the stator blade wheels. An electrical induction motor is incorporated into the pump with its rotor output shaft being the spindle so as to rotate such spindle and, hence, the pump rotor for high vacuum pumping. A photosensor is included for sensing the frequency of rotation of the pump rotor and a slip frequency oscillator is provided to generate a desired constant slip frequency. A control circuit is included for combining the desired slip frequency with the pump rotor frequency of operation in order to drive the stator of the motor with a constant slip frequency.