Power brake booster

A hydraulic booster comprising:

• a housing having a power piston reciprocably received therein to define an inlet power chamber and an outlet exhaust chamber;
• a divider in said inlet power chamber defining with said power piston and said housing a first inlet power chamber section and a second inlet power chamber section, said divider and an element movable with said power piston defining a restrictive flow passage connecting said first and second inlet power chamber sections to permit limited fluid flow therebetween;
• check valve means in said power piston permitting flow of hydraulic fluid from said outlet exhaust chamber to said second inlet power chamber section;
• and control valve means controlling the changes in pressure differential across said power piston to actuate and release said booster;
• said first inlet power chamber being pressurized upon booster actuation at a pressure rate of increase determined by operation of said valve means, and when pressurized at a pressure rate of increase greater than that which can be transmitted through said restrictive flow passage acting to move said power piston to increase the volume of both of said inlet power chamber sections, said check valve means opening to supply fluid from said outlet exhaust chamber to said second inlet power chamber section until the supply of fluid through said restrictive flow passage from said first inlet power chamber section transmits pressure therethrough, after which both of said inlet power chamber sections are pressurized.

In a power booster having a housing divided into a pressure chamber and an exhaust chamber by a movable power wall having an effective area across which pressure differentials may be established,

• a divider in said pressure chamber separating said pressure chamber into a first section having a first portion of the power wall effective area as one side thereof and a second section having a second portion of the power wall effective area as one side thereof,
• means including said divider and an element movable with said power wall defining a restrictive flow passage connecting said pressure chamber sections which limits fluid flow therebetween to a predetermined maximum rate,
• first check valve means in said power wall connecting said exhaust chamber and said second pressure chamber section in fluid flow relation only when pressure in said exhaust chamber is greater than pressure in said second pressure chamber section,
• second check valve means in said divider connecting said first and second pressure chamber sections in fluid flow relation only when pressure in said second pressure chamber section is greater than pressure in said first pressure chamber section,
• and control valve means for controlling the pressure differentials across said power wall.