Patent ID: 6637838
Filing Date: 2003-10-28
Classification: B60T

Abstract:
A pneumatic booster comprising:a front shell element having a bottom portion and an outer cylindrical portion extending from an outer edge of said bottom portion, said front shell element further having an inner cylindrical portion projecting from said bottom portion in a same direction as a direction of extension of said outer cylindrical portion to receive a master cylinder; a rear shell element engaged with said outer cylindrical portion of said front shell element to close an opening edge of said outer cylindrical portion to form a shell body; a valve body provided to extend through said rear shell element, said valve body having a valve mechanism therein; and at least one power piston engaged with said valve body to divide an interior of said shell body into a plurality of chambers, wherein said outer cylindrical portion of said front shell element has at least one reduced-diameter portion smaller in diameter than said opening edge, and said inner cylindrical portion of said front shell element has at least one reduced-diameter portion smaller in diameter than a proximal end edge of said inner cylindrical portion at said bottom portion, so that when a plurality of front shell elements as constituent parts before assembly are stacked on one another, both the outer cylindrical portions and the inner cylindrical portions of adjacent front shell elements are fitted in each other, respectively, wherein at least one of said outer cylindrical portion and said inner cylindrical portion of said front shell element has a frusto-conical shape gradually increasing in diameter from said reduced-diameter portion, and wherein said reduced-diameter portion of at lease one of said outer cylindrical portion and said inner cylindrical portion of said front shell element forms a stopper portion having a step, said stopper portion abutting on a corresponding cylindrical portion of an adjacent front shell element so that said stopper portion regulates a depth of fitting between each pair of adjacent front shell elements when the plurality of front shell elements as constituent parts before assembly are stacked on one another.