Patent ID: 7040717
Filing Date: 2006-05-09
Classification: B60T

Abstract:
1. A negative pressure boosting device comprising: a valve body which is arranged to freely move forward and backward relative to a space defined by a shell and airtightly and slidably penetrates said shell; a power piston which is connected to said valve body and divides said space into a constant pressure chamber in which negative pressure is introduced and a variable pressure chamber in which atmosphere is introduced during operation; a valve plunger which is movably arranged in said valve body; an input shaft which is connected to said valve plunger and is arranged in said valve body to allow forward and backward movements of said input shaft relative to said valve body; an output shaft which moves together with said valve body by operation of said power piston to produce an output; a vacuum valve which is arranged in said valve body and is controlled by forward and backward movements of said valve plunger to impede or allow communication between said constant pressure chamber and said variable pressure chamber; an atmospheric valve which is arranged in said valve body and is controlled by the forward and backward movements of said valve plunger to impede or allow communication between said variable pressure chamber and the atmosphere; input stroke shortening means for shortening a stroke of said input shaft relative to a stroke of said output shaft in an initial stage of operation, said input stroke shortening means increasing an opening of the atmospheric valve by pushing backward the atmospheric valve in an initial stage of a normal operation; and rapid output intensifying means for intensifying said output more rapidly than that of the normal operation when said input shaft is operated more rapidly than that for the normal operation.