Hydraulic booster brake mechanism

Claim 2

In a hydraulic booster brake mechanism for energizing a master cylinder which supplies pressure to the wheel cylinders of a vehicle comprising; a housing including an inlet, an outlet and a supply chamber in communication with said inlet, piston means shiftable in said housing and forming a control chamber at one side thereof, control valve means for admitting fluid pressure from said supply chamber to said control chamber for shifting said piston in said housing, demand valve means shiftable between a first position in which substantially all fluid flowing into said inlet is directed to said outlet and the pressure level is low and a second position in which fluid flow is restricted and the pressure leVel at said inlet is high with the pressure level becoming successively higher as said valve means is shiftable from said first position toward said second position, said demand valve means being shiftable toward said second position in response to a pressure in said control chamber greater than at said inlet whereby the pressure in said supply chamber is increased.

Claim 3

The booster brake mechanism set forth in claim 1 in which said demand valve means is responsive to pressure at said inlet greater than pressure in said control chamber to maintain said demand valve in said first position.

Claim 4

The booster brake mechanism set forth in claim 2 and further comprising spring means biasing said demand valve means toward said second position in the absence of pressure in said inlet.

Claim 5

The booster brake mechanism set forth in claim 1 in which said demand valve means includes a bore in said housing, a piston in said bore forming first and second chambers at opposite sides thereof, said first chamber communicating with said inlet and said supply chamber and said second chamber communicating with said control chamber.

Claim 6

The booster brake mechanism set forth in claim 1 in which said demand valve has a first pressure responsive area exposed to the pressure at said inlet and a second pressure responsive area exposed to the pressure in said control chamber and opposing said first pressure responsive area, said second pressure responsive area being larger than said first pressure responsive area whereby said demand valve is urged toward said second position to maintain a pressure in said supply chamber greater than the pressure in said power chamber.

Claim 7

In an hydraulic booster mechanism for use in a system having a source of continuously circulating fluid pressure, a housing having an inlet connected to said source, said housing defining a bore, a piston slidable in said bore and forming a power chamber therein at one side of said piston, a fluid supply chamber in said housing communicating with said inlet, control valve means operatively disposed between said fluid supply chamber and said power chamber and being selectively operable for admitting said circulating fluid pressure from said supply chamber to said power chamber for moving said power piston towards one end of said bore, and demand valve means operatively disposed between said inlet and said supply chamber and being movable between a first position in which said inlet is open and pressure level is low and a second position in which said inlet is restricted and the pressure level is higher, said demand valve means being urged toward said first position in response to pressure from said inlet and toward said second position in response to pressure in said power chamber whereby the pressure differential in said power chamber and at said inlet determine the degree of restriction at said inlet.

Claim 8

In an hydraulic booster mechanism for use in a system having a source of continuously circulating fluid pressure, a housing having an inlet connected to said source, said housing defining a bore, a piston slidable in said bore and forming a power chamber therein at one side of said piston, a fluid supply chamber in said housing communicating with said inlet, control valve means operatively disposed between said fluid supply chamber and said power chamber and being selectively operable for admitting said circulating fluid pressure from said supply chamber to said power chamber for moving said power piston towards one end of said bore, and demand valve means operatively disposed between said inlet and said supply chamber and being movable between a first position in which said inlet is open and pressure level is low and a second position in which said inlet is restricted and the pressure level is higher, said demand valve means being urged toward said first position in response to pressure from said inlet and toward said second position in response to pressure in said power chamber whereby the pressure differential in said power chamber and at said inlet determine the degree of restriction at said inlet.

Claim 9

The hydraulic booster brake mechanism set forth in claim 6 in which said demand valve means includes piston means having opposite sides exposed to pressure at said inlet and in said power chamber, respectively, said piston side exposed to said inlet being less responsive to pressure than said piston side exposed to said power chamber whereby the pressure at said inlet is maintained higher than the pressure in said power chamber.

Claim 10

The hydraulic booster brake mechanism set forth in claim 6 and further comprising pressure regulating means operatively disposed between said demand valve means and said supply chamber and being operative to isolate said supply chamber when the pressure in the latter is at a predetermined maximum.

Claim 11

In a hydraulic booster brake mechanism for use with a continuously circulating source of fluid pressure, a housing having an inlet and an outlet, passage means in said housing communicating said inlet with said outlet, demand valve means operatively associated with said passage means and being movable between a first position in which said passage means is open and the pressure level at Said inlet is low and a second position in which said passage means is restricted and the pressure level at said inlet is high, a power piston movable in said housing and forming a power chamber at one side thereof, a fluid supply chamber in said housing and communicating with said passage means between said inlet and said demand valve means, control valve means operatively disposed between said supply chamber and said power chamber and being selectively operable to admit fluid to said power chamber for moving said power piston, and means for moving said demand valve means from said first position toward said second position in response to pressure in said power chamber.

Claim 12

In a hydraulic booster brake mechanism for use with a continuously circulating source of fluid pressure, a housing having an inlet and an outlet, passage means in said housing communicating said inlet with said outlet, demand valve means operatively associated with said passage means and being movable between a first position in which said passage means is open and the pressure level at Said inlet is low and a second position in which said passage means is restricted and the pressure level at said inlet is high, a power piston movable in said housing and forming a power chamber at one side thereof, a fluid supply chamber in said housing and communicating with said passage means between said inlet and said demand valve means, control valve means operatively disposed between said supply chamber and said power chamber and being selectively operable to admit fluid to said power chamber for moving said power piston, and means for moving said demand valve means from said first position toward said second position in response to pressure in said power chamber.

Claim 13

The booster brake mechanism set forth in claim 9 in which said means for moving said demand valve means includes piston means forming a first pressure responsive surface at one side communicating with said supply chamber and a second pressure responsive surface at the other side communicating with said power chamber, said first pressure responsive surface being smaller than said second pressure responsive surface whereby the pressure in said supply chamber is maintained at a higher pressure than in said power chamber.