Vacuum intensified brake booster system

Claim 1

A power braking system for a vehicle comprising: means in a vehicle for reducing the pressure of a first source of fluid below atmospheric pressure to create a partial vacuum; servomotor means having an interior divided into a first control chamber and a first power chamber by a first movable wall means, said first control chamber and said first power chamber being connected to said first source of fluid; control valve means being responsive to an operator for preventing said first source of fluid to be communicated to said control chamber and for allowing air under atmospheric pressure to freely flow to said control chamber, said atmospheric pressure and said partial vacuuM of said first fluid creating a pressure differential across said first movable wall means, said pressure differential causing said first movable wall means to move and pressurize an operational fluid to activate the braking system; first valve means located in a supply conduit adjacent said first control chamber for permitting said first fluid to flow in only one direction; intensifying means having a housing with a sensing chamber connected to the first power chamber of the servomotor and the pressure reducing means, and with an evacuation chamber connected to said first valve means and the pressure reducing means through a second valve means; second movable wall means located in said sensing chamber for comparing the partial vacuum present in the first power chamber of the servomotor and the partial vacuum being produced by said pressure reducing means; third movable wall means for dividing the evacuation chamber into a front chamber and a rear chamber, said rear chamber being connected to said power chamber through the first valve means; and intensifier control means responsive to said second movable wall means for alternately porting air under pressure from an atmospheric port and partial vacuum from said pressure reducing means to said front chamber for moving the third movable wall means within said evacuation chamber for maintaining the pressure level of the partial vacuum in the first power chamber within a predetermined range to effectively operate said servomotor means; and second valve means located in the supply conduit extending between said intensifying means and said pressure reducing means for sustaining in the intensifying means the pressure level of the partial vacuum produced by said pressure reducing means.