Solenoid powered brake pressure modulator

Claim 2

A brake pressure modulator operable in response to signals of a wheel lock condition and the end of the wheel lock condition for use in a hydraulic brake system having a brake master cylinder, a brake applying cylinder and a reservoir of fluid and comprising: a housing having a fluid inlet port, a fluid outlet port, and a reservoir port adapted tO be connected to the master cylinder, brake applying cylinder and reservoir, respectively, valve means for relieving fluid pressure from said outlet port to said reservoir port in response to a first signal of a wheel lock condition, pump means delivering fluid under pressure to said outlet port in response to a second signal at the end of said wheel lock condition, and solenoid means for operating said valve means in response to said first signal and for operating said pump means in response to said second signal.

Claim 3

The brake pressure modulator defined in claim 1 wherein said pump means includes a chamber formed by said housing, a plunger having a piston portion forming a wall of said chamber, said plunger being slidable in one direction to enlarge said chamber to receive fluid from said reservoir port and in the opposite direction to constrict said chamber to displace fluid therefrom to said outlet port, said plunger being reciprocated by said solenoid at a fixed and controlled rate.

Claim 4

The brake pressure modulator defined in claim 1 wherein said modulator includes a housing forming a chamber therein, said valve means includes passage means formed in said housing between said outlet port and said chamber, and said pump means includes a plunger slidable between a position opening and a position closing said passage.

Claim 5

The brake pressure modulator set forth in claim 2 wherein said valve means includes passage means formed in said housing between said outlet port and said reservoir port and wherein said plunger closes said passage means when said plunger moves in said opposite direction.

Claim 6

The brake pressure modulator defined in claim 2 wherein first valve means are disposed between said chamber and said reservoir port to permit fluid flow from the latter to said chamber and to prevent fluid flow from said chamber to said reservoir, and wherein second valve means are disposed between said chamber and said outlet port to permit fluid flow from said chamber to said outlet port and prevent fluid flow from said outlet port to said chamber.

Claim 7

The brake pressure modulator defined in claim 2 and further comprising additional passage means between said inlet port and said chamber, and additional valve means in said passage means normally being disposed in an open position to permit fluid flow in said passage means, said additional valve means being movable to a closed position in response to a first signal sensing the beginning of a wheel lock condition and remaining in a closed position in the presence of brake applying pressure at said inlet port during subsequent signals.

Claim 8

The brake pressure modulator set forth in claim 6 and further comprising biasing means between said plunger and said additional valve means to maintain said valve open when said plunger is in a first position prior to said first signal of a wheel lock condition and movable with said plunger to a second position to permit closing of said valve means in response to said first signal.

Claim 9

A brake pressure modulator operable in response to signals of wheel lock condition and the end of the wheel lock condition for use in a hydraulic brake system having a brake master cylinder and a brake applying when cylinder and comprising; a housing having a fluid inlet port, a fluid outlet port, and a fluid reservoir port adapted to be connected to the master cylinder, the wheel cylinder and a source of hydraulic fluid, respectively, a chamber formed in said housing and connected to said ports, a plunger slidable in said housing between first and second positions and forming a movable wall in said chamber, solenoid means for moving said plunger in response to said signals, first passage means communicating said inlet port with said outlet port and normally being opend when said plunger is in a first position, valve means in said first passage means normally being open to permit communication between said inlet and outlet ports, second passage means communicating said outlet port and said chamber and noRmally being closed by said plunger when the latter is in a first position, said plunger being movable from said first to a second position in response to an initial signal of a wheel lock condition to close said valve means and to open said second passage means to relieve pressure at said outlet port, said plunger being reciprocated continuously between said second and first positions in response to a signal at the end of said wheel lock condition and until a subsequent signal of a subsequent wheel lock condition to admit fluid from said outlet port to said chamber upon movement of said plunger to said first position to increase brake applying pressure at said outlet port independently of the pressure at said inlet port.

Claim 10

A brake pressure modulator operable in response to signals of wheel lock condition and the end of the wheel lock condition for use in a hydraulic brake system having a brake master cylinder and a brake applying when cylinder and comprising; a housing having a fluid inlet port, a fluid outlet port, and a fluid reservoir port adapted to be connected to the master cylinder, the wheel cylinder and a source of hydraulic fluid, respectively, a chamber formed in said housing and connected to said ports, a plunger slidable in said housing between first and second positions and forming a movable wall in said chamber, solenoid means for moving said plunger in response to said signals, first passage means communicating said inlet port with said outlet port and normally being opend when said plunger is in a first position, valve means in said first passage means normally being open to permit communication between said inlet and outlet ports, second passage means communicating said outlet port and said chamber and noRmally being closed by said plunger when the latter is in a first position, said plunger being movable from said first to a second position in response to an initial signal of a wheel lock condition to close said valve means and to open said second passage means to relieve pressure at said outlet port, said plunger being reciprocated continuously between said second and first positions in response to a signal at the end of said wheel lock condition and until a subsequent signal of a subsequent wheel lock condition to admit fluid from said outlet port to said chamber upon movement of said plunger to said first position to increase brake applying pressure at said outlet port independently of the pressure at said inlet port.

Claim 11

The brake pressure modulator defined in claim 8 and further comprising an auxiliary fluid passage formed in said housing between said reservoir port and said chamber, said auxiliary passage being closed by said plunger in its first position and being open to admit fluid from said reservoir port when said plunger is in said second position.

Claim 12

The brake pressure modulator defined in claim 8 and further comprising check valve means between said reservoir port and chamber to prevent fluid flow from the latter to said reservoir port.

Claim 13

The brake pressure modulator defined in claim 10 and further comprising additional solenoid means for permitting fluid communication between said outlet port and said reservoir port in response to a signal moving said plunger from said first to said second position.

Claim 14

The brake pressure modulator defined in claim 11 in which said additional solenoid means responds to said signal faster than said solenoid means moving said plunger.

Claim 15

The brake pressure modulator set forth in claim 8 and further comprising first check valve means between said outlet port and said chamber and preventing communication between the latter and said outlet port when said plunger moves from first to said second position, and second check valve means between said chamber and reservoir port and preventing communication between the latter and said chamber when said plunger moves from said second to said first position.

Claim 16

The brake pressure modulator defined in claim 13 and further comprising third check valve means between said inlet port and said outlet port and normally being closed in the presence of pressure at said inlet port.

Claim 17

The brake pressure modulator defined in claim 13 and further comprising additional solenoid means for moving said second check valve means to an open position permitting fluid communication from said outlet port to said reservoir port to said chamber in response to a signal moving said plunger from said first to said second position.