Brake boosters for automotive vehicles

Claim 1

An improved vehicle brake booster of the type having a casing that is divided into two chambers, a low-pressure chamber and a working chamber, the chambers being divided from each other in a sealed manner by an axially movable wall, the improvement comprising: a reinforcement tube axially extending through said booster casing and fastened to the end walls of said casing, said reinforcement tube having a plurality of longitudinal slots of substantial width disposed in its periphery; a rolling diaphragm forming a fold and disposed in a sealed relationship with said movable wall and said reinforcement tube; a mechanically actuatable control valve for connecting said working chamber to a selected one of said low-pressure chamber or the atmosphere including a housing disposed generally coaxially in and axially movable within said reinforcement tube; a longitudinal sheet metal sleeve disposed generally coaxially and axially movable within said reinforcement tube, one end of said sleeve being connected to said control valve housing and the other end of said sleeve engaging a plurality of radial ribs of said movable wall, said ribs also being of substantial width and projecting through and slidable in said reinforcement tube longitudinal slots and said ribs further including flat tongues disposed in a common plane transverse to a longitudinal axis of said casing, said sleeve including a radially and outwardly angled collar at said other end of said sleeve of substantial width, said collar engaging at least one acutely angled flat tongue of said movable wall radial rib on a side of said rib adjacent said low-pressure chamber to hold the ribs against the sleeve to prevent relative axial movement, said substantial width of said collar and said radial ribs distributing substantial bending stresses transmitted thereto during operation of the brake booster; and the distance between the fold of said rolling diaphragm and the adjacent end of said reinforcement tube longitudinal slots is at least equal to one-half the power stroke of said movable wall.