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:
Aug. 27, 1991
Filed:
Dec. 28, 1990
Iwaji Shiomi, Tokyo, JP;
Nitto Kohki Co., Ltd., Tokyo, JP;
Abstract
A piston and a plurality of passages (first to fourth or fifth passages) are provided in a cylinder for reciprocation, which piston has a recessed portion formed in the central part thereof, so that the suction system of two suction pumps can automatically be switched between a parallel coupling and a series coupling depending on the piston's position in the cylinder. The pressure in a pressure chamber provided adjacently to the cylinder is changed by means of a pilot valve provided so as to operate when the negative pressure of the pumps become a predetermined value, and the piston is moved between its first and second positions by means of a diaphragm which constitutes a part enclosure of the pressure chamber and deforms in response to the change of the pressure in the pressure chamber, thereby the suction system is switched from parallel to series or vice versa.