Hydraulic brake booster

Claim 2

An hydraulic brake booster for a vehicle having brake activating means, a pressure source, an hydraulic power control system, a reservoir, an hydraulic circuit for supplying hydraulic pressure fluid from said source to said power control system and returning the hydraulic pressure fluid from said power control system to said reservoir, and a brake master cylinder comprising: a cylinder for interposition within said circuit between said source and said power control system, said last-named cylinder being provided with a bore therein and with inlet means, outlet means and drain means respectively in communication with said source, said power control system and said reservoir; reciprocable means within said bore of said last-named cylinder for forming at one end thereof a drain chamber in communication with said drain means, said reciprocable means being operably connectible with said master cylinder and being provided with a bore therein; control means reciprocably engaged within both of said bores of said last-named cylinder and said reciprocable means to form a pressure chamber between the other end of said reciprocable means and said control means, said control means being operably connectible to the brake activating means of the vehicle and being provided with a bore therein; passage means for connecting said inlet means to said outlet means, said passage means including flow regulating means for controlling operating fluid flow within said passage means in response to relative displacements of said reciprocable means and said control means; a valve piston slidably engaged within said bore of said control means and being operably connectible through resilient means to the brake activating means; first valve means cooperating with said valve piston for selectively opening and closing communication between said pressure chamber and said drain chamber; and second valve means for controlling communication between said pressure chamber and said passage means through said flow regulating means in response to relative displacements of said control means and said valve piston, said first and second valve means being arranged radially inside said flow regulating means.

Claim 3

An hydraulic brake booster for a vehicle having brake activating means, a pressure source, an hydraulic power control system, a reservoir, an hydraulic circuit for applying hydraulic pressure fluid from said source to said power control system and returning the hydraulic pressure fluid from said power control system to said reservoir, and a brake master cylinder comprising: a cylinder for interposition within said circuit between said source and said power control system, said last-named cylinder being provided with a bore which has an inlet port, an outlet port and a drain port respectively for communication with said source, said power control system and said reservoir; a booster piston reciprocable within the bore of said last-named cylinder and forming at one end thereof a drain chamber in communication with said drain port, said booster piston being operably connectible with said master cylinder and being provided with a bore therein, a stepped piston reciprocably engaged within both of said bores of said last-named cylinder and said booster piston to form a pressure chamber between the other end of said booster piston and said stepped piston, said stepped piston being operably connectible to the brake activating means of the vehicle and beinG provided with a bore therein; passage means extending in said last-named cylinder, said booster piston and said stepped piston for connecting said inlet port to said outlet port, said passage means including flow regulating means formed by relatively slidable duct openings in said booster piston and said stepped piston for controlling operating fluid flow within said passage means in response to relative displacements of the booster and stepped pistons; a valve piston having an axial bore slidably engaged within said bore of said stepped piston and being operably connectible through resilient means to said brake activating means; a first valve means cooperating with a seat at one end of said valve piston for selectively opening and closing communication between said pressure chamber and said drain chamber; and a second valve means including a valve element at the other end of said valve piston for seating against a seat on said stepped piston for controlling communication between said pressure chamber and said passage means through said flow regulating means in response to relative displacements of said stepped piston and said valve piston, said first and second valve means being disposed radially inwardly of said flow regulating means.

Claim 4

An hydraulic brake booster for a vehicle having brake activating means, a pressure source, an hydraulic power control system, a reservoir, an hydraulic circuit for applying hydraulic pressure fluid from said source to said power control system and returning the hydraulic pressure fluid from said power control system to said reservoir, and a brake master cylinder comprising: a cylinder for interposition within said circuit between said source and said power control system, said last-named cylinder being provided with a bore which has an inlet port, an outlet port and a drain port respectively for communication with said source, said power control system and said reservoir; a booster piston reciprocable within the bore of said last-named cylinder and forming at one end thereof a drain chamber in communication with said drain port, said booster piston being operably connectible with said master cylinder and being provided with a bore therein, a stepped piston reciprocably engaged within both of said bores of said last-named cylinder and said booster piston to form a pressure chamber between the other end of said booster piston and said stepped piston, said stepped piston being operably connectible to the brake activating means of the vehicle and beinG provided with a bore therein; passage means extending in said last-named cylinder, said booster piston and said stepped piston for connecting said inlet port to said outlet port, said passage means including flow regulating means formed by relatively slidable duct openings in said booster piston and said stepped piston for controlling operating fluid flow within said passage means in response to relative displacements of the booster and stepped pistons; a valve piston having an axial bore slidably engaged within said bore of said stepped piston and being operably connectible through resilient means to said brake activating means; a first valve means cooperating with a seat at one end of said valve piston for selectively opening and closing communication between said pressure chamber and said drain chamber; and a second valve means including a valve element at the other end of said valve piston for seating against a seat on said stepped piston for controlling communication between said pressure chamber and said passage means through said flow regulating means in response to relative displacements of said stepped piston and said valve piston, said first and second valve means being disposed radially inwardly of said flow regulating means.

Claim 5

A hydraulic brake booster as claimed in claim 2, wherein said cylinder is mounted on said brake master cylinder.

Claim 6

A hydraulic brake booster as claimed in claim 2, wherein resilient means is disposed within said drain chamber between one end wall of said last-named cylinder and one end of said booster piston so as to normally bias said booster piston in a predetermined position.

Claim 7

A hydraulic brake booster as claimed in claim 4, wherein said resilient means is a coiled compression spring.

Claim 8

An hydraulic brake booster as claimed in claim 2, wherein said first valve means includes a ball valve substantially centered with and cooperating with said axial bore formed in said valve piston to connect said pressure chamber with said drain chamber, and said second valve means includes a spring normally biasing said valve element toward said valve seat on the stepped piston.

Claim 9

An hydraulic brake booster as claimed in claim 2, wherein said inlet port is positioned between said outlet port and said drain port.

Claim 10

An hydraulic brake booster as claimed in claim 2, wherein said booster piston and a piston of said master cylinder are connected to each other by a connecting rod and further including resilient means interposed between said stepped piston and said connecting rod to normally bias said stepped piston toward the brake activating means.

Claim 11

A hydraulic brake booster as claimed in claim 8, wherein said resilient means is a coiled compression spring.

Claim 12

An hydraulic brake booster as claimed in claim 2, wherein said bore of the last-named cylinder is a stepped bore, the smaller diameter portion of said stepped piston engaging that portion of the bore of said booster piston which is positioned in the larger diameter portion of said stepped bore and the larger diameter portion of said stepped piston engaging the smaller diameter portion of said stepped bore of the last-named cylinder, said pressure chamber being formed between a shoulder portion of said stepped piston and said booster piston.

Claim 13

An hydraulic brake booster as claimed in claim 2, wherein said passage means comprises a first passage connecting said inlet port with the bore of said booster piston and a second passage connecting said bore of said booster piston with said outlet port.

Claim 14

A hydraulic brake booster as claimed in claim 11, wherein said flow regulating means is formed between said first and second passages by a pair of annular grooves respectively formed on the bore wall of said booster piston and on the outer wall of said stepped piston.

Claim 15

An hydraulic brake booster as claimed in claim 11, wherein said passage means includes a third passage connecting said first passage with said pressure chamber, said second valve means being formed within said third passage.

Claim 16

A hydraulic brake booster as claimed in claim 13, wherein said third passage includes an orifice therein.

Claim 17

A hydraulic brake booster as claimed in claim 13, wherein said first passage and second passage are connected to each other by way of a bypass passage including an orifice therein.