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:
Apr. 09, 1985
Filed:
Nov. 15, 1983
Applicant:
Inventors:
Mitsuyoshi Yokota, Hyogo, JP;
Akio Matsumoto, Hyogo, JP;
Assignee:
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G05B / ;
U.S. Cl.
CPC ...
318484 ; 303 12 ; 307144 ; 318481 ;
Abstract
A control device for a vacuum pump apparatus in which a hunting effect is substantially eliminated. A pressure-sensitive switch senses a negative pressure produced by a vacuum pump, the latter being driven by a d.c. motor. The switch has at least three contacts, the positions of which are changed at two different pressures. The output of the switch is compared with a fixed reference value, and the comparison result used to drive the d.c. motor. The d.c. motor is thus provided with hysteretic drive characteristic, thereby maintaining the vacuum pressure between the two predetermined values and eliminating the hunting effect.