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:
Jan. 29, 1991
Filed:
Feb. 16, 1989
Nissin Kogyo Kabushiki Kaisha, Ueda, JP;
Abstract
A tandem-type vacuum booster comprises a partition plate fixedly mounted in a booster shell for partitioning the interior of the booster shell into a front shell chamber and a rear shell chamber; a front booster piston dividing said front shell chamber into a front-side fore vacuum chamber connected to a vacuum pressure source and a rear-side fore operating chamber; a rear booster piston dividing the rear shell chamber into a front-side hind vaccum chamber and a rear-side hind operating chamber, the both booster pistons being interconnected through a piston boss slidably carried on the partition plate and connected to an output rod; a valve tube integrally connected to the piston boss to project from a rear end of the piston boss and slidably supported on a rear wall of the booster shell; a first port permitting the interior of the valve tube to communicate with both the vaccum chambers; a second port permitting the interior of the valve tube to communicate with both the operating chambers, the first port being comprised of an axial port permitting the communication between the fore vacuum chamber and the valve tube and a radial port permitting the communication between the axial port and the hind vaccum chamber; an input rod movable back and forth within the valve tube; and a control valve for changing over the communications of the second port with the first port and the atmosphere depending upon the backward and forward movements of the input rod, the input rod and the control valve being disposed within the valve tube. In such tandem-type vacuum booster, a portion, closer to the fore vacuum chamber, of the opened edge of the radial port which is closer to the axial port is offset radially outwardly more than a portion closer to the valve tube to provide a step between both the portions. This makes it possible to provide a silent vaccum bosster in which the air-cutting-through noise is prevented.