Fluid servo valve for a power steering gear

Claim 1

IN A FLUID SERVO VALVE FOR A POWER STEERING GEAR HAVING A FLUID OPERATED PISTON THE COMBINATION COMPRISING, A HOUSING, AN INPUT MEMBER AND AN OUTPUT MEMBER ROTATABLY POSITIONED COAXIALLY WITHIN SAID HOUSING, SAID INPUT AND OUTPUT MEMBERS BEING COUPLED BY A LOST MOTION CONNECTION, A FIRST VALVE PLATE CONNECTED TO SAID INPUT MEMBER AND HAVING A FIRST FACE AND A SECOND FACE, A SECOND VALVE PLATE CONNECTED TO SAID OUTPUT MEMBER AND HAVING A FIRST FACE AND A SECOND FACE, SAID FIRST AND SAID SECOND VALVE PLATES BEING POSITIONED COAXIALLY WITH RESPECT TO SAID INPUT MEMBER AND SAID OUTPUT MEMBER, THE FACES OF SAID FIRST VALVE PLATE AND SAID SECOND VALVE PLATE BEING POSITIONED SUBSTANTIALLY NORMAL TO THE AXES OF SAID INPUT AND SAID OUTPUT MEMBER, THE SECOND FACE OF SAID FIRST VALVE PLATE BEING POSITIONED AGAINST THE FIRST FACE OF SAID SECOND VALVE PLATE, THE FIRST FACE OF SAID FIRST VALVE PLATE HAVING AN ANNULAR GROOVE POSITIONED THEREIN, MEANS POSITIONED IN SAID HOUSING AND ADAPTED TO DELIVER FLUID UNDER PRESSURE TO SAID ANNULAR GROOVE, A PLURALITY OF SPACED PORTS POSITIONED IN THE SECOND FACE OF SAID FIRST VALVE PLATE COMMUNICATION WITH SAID ANNULAR GROOVE IN SAID FIRST FACE, THE SECOND FACE OF SAID FIRST VALVE PLATE ALSO HAVING A PLURALITY OR RADIALLY EXTENDING GROOVES, A RADIALLY EXTENDING GROOVE BEING POSITIONED THEREIN AND OF EACH OF SAID PORTS, THE SECOND FACE OF SAID SECOND VALVE PLATE HAVING A FIRST ANNULAR GROOVE POSITIONED THEREIN AND A SECOND ANNULAR GROOVE POSITIONED THEREIN RADIALLY SPACED OUTWARDLY FROM SAID FIRST ANNULAR GROOVE, THE FIRST FACE OF SAID SECOND VALVE PLATE HAVING A FIRST GROUP OF PORTS COMMUNICATING WITH SAID FIRST ANNULAR GROOVE IN SAID SECOND FACE OF SAID VALVE PLATE AND A SECOND GROUP OF PORTS COMMUNICATING WITH THE SECOND ANNULAR GROOVE POSITIONED IN SAID SECOND FACE, SPRING MEANS FOR ENGAGING SAID FIRST AND SECOND VALVE PLATES FOR URGING SAID VALVE PLATES IN TO A NEUTRAL POSITION, A PORT IN SAID FIRST GROUP BEING POSITIONED ON ONE SIDE OF EACH OF THE PORTS IN THE SECOND FACE OF SAID FIRST VALVE PLATE AND A PORT IN SAID SECOND GROUP BEING POSITIONED ON THE OTHER SIDE OF EACH OF THE PORTS IN THE SECOND FACE OF SAID FIRST VALVE PLATE, SAID PORTS IN SAID SECOND FACE OF SAID FIRST VALVE PLATE COMMUNICATING EQUALLY WITH PORTS OF SAID FIRST GROUP AND THE PORTS OF SAID SECOND GROUPS, AND THE PORTS OF SAID FIRST GROUP AND SAID SECOND GROUP COMMUNICATING EQUALLY WITH THE RADIAL GROOVES IN THE SECOND FACE OF SAID FIRST VALVE PLATE WHEN THE VALVE IS IN THE NEUTRAL POSITION, RELATIVE ROTATION OF THE VALVE PLATES IN ONE DIRECTION DIRECTING FLUID UNDER PRESSURE INTO ONE OF SAID GROUPS OF PORTS AND INTO SAID FIRST ANNULAR GROOVE IN THE SECOND FACE OF SAID SECOND VALVE PLATE AND RELATIVE ROTATION IN THE OTHER DIRECTION DIRECTING FLUID UNDER PRESSURE INTO THE OTHER OF SAID GROUPS OF PORTS AND INTO SAID SECOND ANNULAR GROOVE IN SAID SECOND FACE OF SAID SECOND VALVE PLATE, CONDUIT MEANS CONNECTED TOS AID FIRST ANNULAR GROOVE IN THE SECOND FACE OF SAID SECOND VALVE PLATE AND ADAPTED TO DELIVER FLUID UNDER PRESSURE TO ONE SIDE OF THE FLUID OPERATED PISTON AND CONDUIT MEANS CONNECTED TO THE SECOND ANNULAR GROOVE IN THE SECOND FACE OF SAID SECOND VALVE PLATE AND ADAPTED TO DELIVER FLUID UNDER PRESSURE TO THE OTHER SIDE OF THE FLUID OPERATED PISTON.