Split hydraulic braking system

Claim 2

In a dual hydraulic brake system for automotive vehicles having front and rear wheels and including two separate hydraulic circuits connected to a master cylinder and each including the hydraulic brakes of a respective set of wheels, and a pressure regulating control valve in one circuit, having an inlet connection to the master cylinder and an outlet connected to the respective hydraulic brakes, and regulating the hydraulic brake pressure at its outlet in accordance with the hydraulic pressure in the master cylinder, the improvement comprising, in combination, a solenoid actuated component operatively connected to said control valve and operable, when actuated, to render said control valve ineffective to regulate the pressure at its outlet to maintain its outlet pressure substantially equal to the master cylinder pressure; a solenoid operable to actuate said component; an energizing circuit for said solenoid including a source of electric potential; and pressure differential responsive switch means in said energizing circuit and connected to both hydraulic circuits between said master cylinder and said control valve, said switch means, responsive to a pressure difference between said hydraulic circuits, controlling said solenoid to actuate said compoNent.

Claim 3

In a dual hydraulic brake system, the improvement claimed in claim 1, in which said pressure regulating control valve comprises a body formed with a cylindrical bore communicating with said inlet and said outlet, and a piston displaceable in said bore and controlling communication between said inlet and said outlet; said component, when actuated, being movable into said bore to engage said piston and displace said piston to a position providing substantially unrestricted communication between said inlet and said outlet.

Claim 4

In a dual hydraulic brake system, the improvement claimed in claim 2, in which said piston is formed with a passage therethrough communicating with said inlet and outlet ports; and a poppet valve mounted in said piston and controlling flow of fluid through said passage; said component, when actuated, displacing said poppet valve to a position opening said passage.

Claim 5

In a dual hydraulic brake system, the improvement claimed in claim 3, wherein said poppet valve has an operating head projecting from an end of said piston and engageable with an end closure of said bore upon displacement of said piston to open said poppet valve; said component comprising a solenoid actuated plunger engageable with the opposite end of said piston to displace said piston in a direction to engage said poppet valve with said end closure of said bore to open said poppet valve.

Claim 6

In a dual hydraulic brake system, the improvement claimed in claim 4, in which said solenoid actuated plunger, when actuated, is displaceable in a direction substantially normal to and intersecting the path of movement of said piston.

Claim 7

In a dual hydraulic brake system, the improvement claimed in claim 3, in which said poppet valve has an operating head projecting from one end of said piston; said solenoid actuated component comprising a solenoid actuated plunger axially aligned with said poppet valve and having an inner end normally flush with an end wall of said bore; said poppet valve being engageable with said inner end of said solenoid plunger during displacement of said piston; said solenoid plunger, when actuated, projecting its inner end inwardly of said end wall of said bore to displace said poppet valve to a position opening said passage.

Claim 8

A split hydraulic brake system, as set forth in claim 1, wherein said element comprises a balance piston assembly, said balance piston assembly comprises a casing forming a chamber in axial alignment with the chamber in said control valve assembly, a piston disposed within said chamber in said balance piston assembly, said piston having a pair of axially spaced annular projections thereon, said annular projections on said piston cooperating with the chamber in said casing of said balance piston assembly for dividing said chamber into a first chamber containing one of said annular projections and a second chamber containing the other said annular projection, said first chamber being to one of said hydraulic circuits and said second chamber to the other said hydraulic circuit wherby hydraulic brake fluid is supplied from said master cylinder into said first and second chambers and when a pressure failure occurs in said hydraulic circuit not containing said control valve assembly a pressure differential develops between said first and second chambers and displaces said piston into said control valve assembly for holding said control valve assembly in the non-operative position.

Claim 9

A split hydraulic brake system, as set forth in claim 1, wherein said element comprises a balance piston assembly comprising a casing forming a pair of chambers with the axes thereof extending transversely of the axis of said control valve assembly, a piston member extending between said chambers, each of said chambers being connected, to a different one of said hydraulic circuits, said piston intersecting one end of said control valve assembly and having an engaging piece mounted on said piston, said engaging piece and said piston being axially displaceAble between a center position and an off-center position, said control valve assembly comprising an axially extending valve piston having a recess in the end thereof adjacent said engaging piece on said piston of said balance piston assembly, said recess in said valve piston being arranged to receive said engaging piece on said piston when said engaging piece is in its center position and when a differential pressure occurs between said chambers in said balance piston assembly said engaging piece is displaced into its off-center position and prevents axial displacement of said valve piston for maintaining said control valve assembly in its non-operative position.

Claim 10

A split hydraulic brake system, as set forth in claim 1, wherein said control valve assembly comprises a casing forming a chamber extending in the axial direction, a valve piston positioned within and axially displaceable within the casing in said chamber of said control valve assembly, said element comprising a casing forming a chamber in axial alignment with the chamber in said casing of said control valve assembly, a piston positioned within the chamber in said casing of said element, a spring positioned within the chamber in said casing of said element for biasing said piston toward said piston in said control valve assembly, said piston cooperating with the chamber in said casing of said element for forming a second chamber in the end thereof adjacent said control valve assembly, means for supplying pressurized brake fluid from said hydraulic circuit not containing said control valve assembly into said second chamber, said spring arranged to counterbalance the pressure in the second chamber for maintaining said piston therein in a balanced position, whereby when a decrease in pressure takes place within said second chamber said spring axially displaces said piston relative to said control valve assembly for maintaining said control valve assembly in the non-operative position.

Claim 11

In a dual hydraulic brake system, the improvement claimed in claim 1, in which one hydraulic circuit includes the hydraulic brakes of both front wheels and the other hydraulic circuit includes hydrualic brakes of both rear wheels.

Claim 12

A split hydraulic brake system, as set forth in claim 1, wherein said means for sensing the hydraulic brake fluid pressure in said circuit which does not contain said control valve assembly comprises a by-pass valve member, said by-pass valve member comprising a casing forming a chamber therein, a piston axially displaceable within said chamber and dividing said chamber into a first sub-chamber and a second sub-chamber spring means for biasing said piston in one direction, one of said hydraulic circuits connecting said master cylinder and said first sub-chamber, the other hydraulic cylinder connecting said master cylinder and the second sub-chamber, said spring being located within said first sub-chamber, first conduit means connecting said first sub-chamber and said front wheel brake cylinders, second conduit means connecting said second sub-chamber and said rear wheel brake cylinders, said control valve assembly being positioned in said second conduit means, third conduit means connected to said chamber intermediate said first and second sub-chambers for conducting flow of hydraulic brake fluid from said by-pass valve member to said second brake cylinders, whereby when the pressure in said first sub-chamber decreases below the pressure supplied by said master cylinder said piston in said by-pass casing is displaced axially and admits flow of pressurized hydraulic brake fluid from said master cylinder to said third conduit means for supplying the pressurized hydraulic brake fluid to said rear wheel brake cylinders without passage through said control valve assembly in said second conduit means.

Claim 13

In a dual hydraulic brake system, the improvement claimed in claim 1, in which each hydraulic circuit includes the hydraulic brakes of both front wheels and of a respective rear wheel; and each hydraUlic circuit including a respective pressure regulating control valve, a respective solenoid actuated component, and a respective pressure differential responsive switch means controlled solenoid.

Claim 14

In a dual hydraulic brake system, the improvement claimed in claim 1, in which one hydraulic circuit includes the hydraulic brakes of the right front wheel and the left rear wheel, and the other hydraulic circuit includes the hydraulic brakes of the left front wheel and the right rear wheel; each hydraulic circuit including a respective pressure regulating control valve, a respective solenoid actuated component and a respective pressure differential responsive switch means actuated solenoid.

Claim 15

In a dual hydraulic brake system, the improvement claimed in claim 1, in which each hydraulic circuit includes the hydraulic brakes of both front wheels and both rear wheels; each hydraulic circuit including a respective pressure regulating control valve, a respective solenoid actuated component and a respective pressure differential responsive switch means actuated solenoid.

Claim 16

In a dual hydraulic brake system, the improvement claimed in claim 1, in which said solenoid actuated component comprises a by-pass valve connected in parallel with said pressure regulating control valve and operable, when open, to by-pass said pressure regulating control valve; said switch means, responsive to a pressure difference between said hydraulic circuits, controlling said solenoid to open said by-pass valve.

Claim 17

In a dual hydraulic brake system, the improvement claimed in claim 15, in which one hydraulic circuit includes the hydraulic brakes of both front wheels and the other hydraulic circuit includes the hydraulic brakes of both rear wheels.

Claim 18

In a dual hydraulic brake system, the improvement claimed in claim 15, in which each hydraulic circuit includes the hydraulic brakes of both front wheels and of a respective rear wheel; each hydraulic circuit including a respective pressure regulating control valve, a respective said by-pass valve, and a respective pressure differential responsive switch means controlled solenoid operable to open the associated by-pass valve.

Claim 19

In a dual hydraulic brake system, the improvement claimed in claim 15, in which one hydraulic circuit includes the hydraulic brakes of the right front wheel and the rear left wheel, and the other hydraulic circuit includes the hydraulic brakes of the left front wheel and the right rear wheel; each hydraulic circuit including a respective pressure regulating control valve, a respective said by-pass valve, and a respective pressure differential responsive switch means controlled solenoid operable to open the associated by-pass valve.

Claim 20

In a dual hydraulic brake system, the improvement claimed in claim 15, in which each hydraulic circuit includes the hydraulic brakes of both front wheels and of both rear wheels; each hydraulic circuit including a respective pressure regulating control valve, a respective said by-pass valve and a respective pressure differential responsive switch means controlled solenoid operable to open the associated by-pass valve.

Claim 21

A dual hydraulic brake system for an automotive vehicle comprising a master cylinder for supplying pressurized hydraulic brake fluid to a hydraulic brake system, two separate hydraulic circuits connected to said master cylinder, a first set of brake cylinders positioned in one of said hydraulic circuits and arranged to supply braking force to the front wheels of the automotive vehicle, a second set of brake cylinders positioned in the other one of said hydraulic circuits and arranged to supply braking force to the rear wheels of the automotive vehicle, a control valve assembly arranged in one of said circuits for varying the pressure of the hydraulic brake fluid supplied to the wheels in said circuit, and means for sensing the hydraulic brake fluid pressure in said circuit which does not contain said control valve assembly; said means being arranged in communiCation with said control valve assembly so that, when a failure occurs in the pressure of the hydraulic brake fluid of said circuit not containing said control valve assembly, said control valve assembly is rendered inoperative and the full pressure from said master cylinder is delivered to said brake cylinders in said circuit containing said control valve; said means for sensing the hydraulic brake fluid pressure comprising a differential pressure switch disposed across each of said hydraulic circuits, and a solenoid-actuated by-pass valve member, said by-pass valve member comprising a casing forming a chamber, a poppet valve contained within said chamber, a solenoid actuated armature positioned within said chamber and axially displaceable therein into contact with said poppet valve, conduit means for connecting said by-pass valve member to said hydraulic circuit containing said control valve assembly with said by-pass valve member being connected to said hydraulic circuit upstream and downstream from said control valve assembly, so that, when a failure occurs in said hydraulic circuit not containing said control valve assembly, said by-pass valve member is held in the opened position for supplying full master cylinder pressure around said control valve assembly.

Claim 22

A dual hydraulic brake system for an automotive vehicle comprising a master cylinder for supplying pressurized hydraulic brake fluid to a hydraulic brake system, two separate hydraulic circuits connected to said master cylinder, a first set of brake cylinders positioned in one of said hydraulic circuits and arranged to supply braking force to the front wheels of the automotive vehicle, a second set of brake cylinders positioned in the other one of said hydraulic circuits and arranged to supply braking force to the rear wheels of the automotive vehicle, a control valve assembly arranged in one of said circuits for varying the pressure of the hydraulic brake fluid supplied to the wheels in said circuit, and means for sensing the hydraulic brake fluid pressure in said circuit which does not contain said control valve assembly; said means being arranged in communiCation with said control valve assembly so that, when a failure occurs in the pressure of the hydraulic brake fluid of said circuit not containing said control valve assembly, said control valve assembly is rendered inoperative and the full pressure from said master cylinder is delivered to said brake cylinders in said circuit containing said control valve; said means for sensing the hydraulic brake fluid pressure comprising a differential pressure switch disposed across each of said hydraulic circuits, and a solenoid-actuated by-pass valve member, said by-pass valve member comprising a casing forming a chamber, a poppet valve contained within said chamber, a solenoid actuated armature positioned within said chamber and axially displaceable therein into contact with said poppet valve, conduit means for connecting said by-pass valve member to said hydraulic circuit containing said control valve assembly with said by-pass valve member being connected to said hydraulic circuit upstream and downstream from said control valve assembly, so that, when a failure occurs in said hydraulic circuit not containing said control valve assembly, said by-pass valve member is held in the opened position for supplying full master cylinder pressure around said control valve assembly.