Dual-cylinder hydraulic actuator for automotive clutch and brake control

Claim 1

IN A DUAL-CYLINDER HYDRAULIC ACTUATOR HAVING A BODY CHARACTERIZED BY AN INNER AND AN OUTER CYLINDRICALLY WALLED CYLINDER IN TELESCOPIC CONCENTRIC OVERLAPPING RELATIONSHIP, A FLUID SUPPLY RESERVOIR FOR SAID CYLINDERS, SEPARATE PRESSURE OUTPUT LINES FROM SAID CYLINDERS, RESPECTIVELY, CONNECTED TO CONVEY ACTUATING FLUID TO OPERATE THE MAIN VEHICLE CLUTCH AND SERVICE BRAKES OF A MOTOR VEHICLE AND THE LIKE, A PAIR OF PISTON UNITS OPERABLY DISPOSED IN SAID CYLINDERS, RESPECTIVELY, FOR WORKING THE FLUID IN THEIR RESPECTIVE WORKING CHAMBERS THEREBETWEEN, A PAIR OF DISCHARGE PORTS FOR SAID WORKING CHAMBERS CONNECTED TO THEIR RESPECTIVE WORKING CHAMBERS THEREBETWEEN, A PAIR OF DISNORMALLY INTERCONNECTING SAID RESERVOIR WITH THE WORKING CHAMBER OF THE OUTER CYLINDER WHEN SAID PISTON UNITS ARE FULLY RETRACTED INTO NORMAL POSITION, A COMMON INTAKE PORT BETWEEN SAID RESERVOIR AND BOTH OF SAID PISTON UNITS, A ONE-WAY MECHANICAL CONNECTION BETWEEN SAID PISTON UNITS, AND WHICH IS OPERATIVE TO MOVE BOTH POSTION UNITS SIMULTANEOUSLY IN A FLUID-PRESSURIZING DIRECTION, A FIXED WALL CLOSING THE ENDS OF SAID WORKING CHAMBERS OPPOSITE SAID PISTON UNITS, A PAIR OF CONCENTRIC ANNULAR STATIC FLUID CHAMBERS BETWEEN CIRCULARLY ALIGNED PORTIONS OF SAID PISTON UNITS, A PASSAGEWAY INTERCONNECTING SAID LASTNAMED CHAMBERS, THE LATTER BEING IN CONTINUOUS COMMUNICATION WITH SAID RESERVOIR FLUID VIA SAID COMMON INTAKE PORT, THE IMPROVEMENT WHICH COMPRISES: AN ANNULAR FIXED WALL SPACED FROM THE FIRST-NAMED FIXED WALL DEFINING AN ANNULAR VALVE CHAMBER BETWEEN THE OUTER WORKING CHAMBER AND ANNULAR FIXED WALL; SHUT-OFF VALVE MEANS INCLUDING A COMPLEMENTAL VALVE-FORMING ELEMENT RECIPROCABLE IN SAID VALVE CHAMBER AND SERVING TO DIVIDE THE SAME INTO TWO FLUID PRESSURE CHAMBERS; SPRING MEANS INCLUDING A NORMALLY COMPRESSED SPRING OPERABLY POSITIONED WITHIN ONE OF SAID FLUID PRESSURE CHAMBERS FOR BIASING SAID VALVEFORMING ELEMENT TOWARD NORMAL POSITION; A PRESSURE INPUT LINE COMMUNICATING WITH THE OTHER FLUID PRESSURE CHAMBER; A PAIR OF FLUID PASSAGES NORMALLY INTERCONNECTING THE WORKING CHAMBER OF SAID OUTER CYLINDER WITH SAID ONE FLUID PRESSURE CHAMBER WHEN SAID VALVE-FORMING ELEMENT IS IN NORMAL POSITION; A LONGITUDINAL PASSAGE PROVIDED IN THE CYLINDRICAL WALL OF THE INNER CYLINDER AND WHICH IS CLOSED AT BOTH ENDS; A PORT IN THE CYLINDRICAL WALL OF THE INNER CYLINDER INTERCONNECTING SAID OTHER FLUID PRESSURE CHAMBER WITH SAID LONGITUDINAL PASSAGE WHEN SAID VALVE-FORMING ELEMENT IS IN NORMAL POSITION; ANOTHER PORT THROUGH A DIFFERENT PORTION OF THE CYLINDRICAL WALL OF SAID INNER CYLINDER FOR INTERCONNECTING SAID LONGITUDINAL PASSAGE WITH THE WORKING CHAMBER OF SAID INNER CYLINDER WHEN BOTH PISTON UNITS ARE IN NORMAL POSITION; A FLUID RETAINING PISTON SLIDABLY DISPOSED IN THE OUTER CYLINDER, AND WHICH DEFINES THE REAR CLOSED ENDS OF THE PAIR OF STATIC FLUID CHAMBERS AFORESAID; A CYLINDRICAL EXTENSION PROJECTING FROM SAID FLUID-RETAINING PISTON INTO SAID INNER CYLINDER; A PAIR OF LONGITUDINALLY SPACED FORE AND AFT ANNULAR WORKING LANDS DEFINING A PORTION OF THE OUTER SURFACE OF SAID EXTENSION WITH THE FORWARD LAND HAVING FRONT AND REAR LEADING EDGES, AND WHICH NORMALLY PROJECTS INTO SAID INNER CYLINDER WITH ITS FRONT LEADING EDGE SPACED FROM SAID LAST-NAMED PORT, SAID REAR WORKING LAND HAVING A FRONT LEADING EDGE ONLY; AN EXTERNAL ANNULAR CHAMBER DEFINED BY THE SPACE BETWEEN SAID WORKING LANDS; AN AXIAL BORE PROCESSED IN THE INNER END PORTION OF THE SAID EXTENSION; A PORT THROUGH THE CYLINDRICAL WALL OF SAID AXIAL BORE COMMUNICATING WITH SAID LAST-NAMED CHAMBER; A HYDRAULIC PRESSURE-PRODUCING SYSTEM INCLUDING A PUMP COMMUNICATING WITH SAID PRESSURE INPUT LINE TO MOVE SAID VALVE-FORMING ELEMENT TO A POSITION AGAINST ITS SPRING BIAS TO BLOCK COMMUNICATION BETWEEN SAID FIRST-NAMED PORT IN THE CYLINDRICAL WALL OF THE INNER CYLINDER AND SAID PAIR OF INTERCONNECTING FLUID PASSAGES AND THEREBY ISOLATING THE WORKING CHAMBERS OF SAID OUTER AND INNER CYLINDERS, TO ENABLE THE FORMER CYLINDER TO OPERATE THE VEHICLE SERVICE BRAKES, AND THE LATTER CYLINDER TO CONTROL HYDRAULIC-DISENGAGEMENT OF SAID VEHICLE CLUTCH; ANOTHER SPRING MEANS INCLUDING A NORMALLY COMPRESSED SPRING OPERATIVELY POSITIONED WITHIN THE OUTER WORKING CHAMBER OF THE OUTER CYLINDER TO REACT BETWEEN SAID ANNULAR FIXED WALL AND SAID OUTER PISTON UNIT TO BIAS BOTH PISTON UNITS TOWARD NORMAL POSITION; AND AN OPERATOR-OPERATED MEMBER OPERABLE FROM NORMAL RELEASED POSITION THROUGH FIRST, SECOND AND THIRD RANGES OF MOVEMENT WHEREBY FIRST RANGE OF MOVEMENT IS EFFECTIVE TO INITIALLY MOVE BOTH PISTON UNITS SIMULTANEOUSLY IN THEIR RESPECTIVE OUTER AND INNER CYLINDERS TO FIRST CLOSE THE AFORESAID PORT IN A DIFFERENT PORTION OF THE CYLINDRICAL WALL OF SAID INNER CYLINDER TO BLOCK NON-ACTIVATING FLUID-FLOW FROM SAID PUMP VIA THE PRESSURE OUTPUT LINE AFORESAID COMMUNICATING WITH THE WORKING CHAMBER OF SAID INNER CYLINDER BACK TO SAID RESERVOIR AND THEREBY INDUCING PRESSURIZATION OF THE FLUID DISPLACED BY SAID PUMP; ANOTHER PRESSURE OUTPUT LINE LEADING FROM SAID LAST-NAMED PRESSURE OUTPUT LINE LEADING CHAMBER OF SAID INNER CYLINDER; A HYDRAULIC CLUTCH-SERVO FOR ACTIVATING THE PISTON THEREOF TO DISENGAGE THE VEHICLE CLUTCH IN RESPONSE TO SAID FLUID PRESSURIZATION; SAID SECOND RANGE OF MOVEMENT OF SAID OPERATOR MEMBER BEING EFFECTIVE TO CLOSE THE AFORESAID COMPENSATING PORT TO CONDITION THE WORKING CHAMBER OF SAID OUTER CYLINDER TO APPLY THE VEHICLE SERVICE BRAKES, AND SEQUENTIALLY DISPOSE THE REAR LEADING EDGE OF THE FORWARD WORKING LAND ON SAID EXTENSION TO PLACE SAID PORT IN A DIFFERENT POSITION OF THE CYLINDRICAL WALL OF SAID INNER CYLINDER IN COMMUNICATION WITH THE ANNULAR FLUID CHAMBER DISPOSED BETWEEN SAID WORKING LANDS, AND THEREBY RELEASING SAID PRESSURIZED FLUID INTO SAID RESERVOIR TO ACCOMMODATE AUTOMATIC RE-ENGAGEMENT OF SAID VEHICLE CLUTCH WHILE SAID OUTER PISTON UNIT MAINTAINS THE VEHICLE SERVICE BRAKES APPLIED; AND SAID THIRD RANGE OF MOVEMENT OF SAID OPERATOR MEMBER BEING EFFECTIVE TO PROJECT THE FRONT LEADING EDGE OF SAID REAR WORKING LAND ON SAID EXTENSION INTO THE OPEN END OF SAID INNER CYLINDER TO ISOLATE SAID ANNULAR FLUID CHAMBER BETWEEN SAID WORKING LANDS FROM SAID RESERVOIR FLUID WHEREBY FLUID DISPLACED BY THE WORKING CHAMBER OF SAID INNER CYLINDER COOPERATES WITH THAT BEING DISPLACED BY THE WORKING CHAMBER OF SAID OUTER CYLINDER WHEN THE SAID VALVEFORMING ELEMENT IS IN NORMAL POSITION INTERCONNECTING SAID PAIR OF FLUID PASSAGES WITH THE FIRST-NAMED PORT IN THE CYLINDRICAL WALL OF SAID INNER CYLINDER, TO APPLY THE VEHICLE SERVICE BRAKES AND ACTUATE THE HYDRAULIC CLUTCHSERVO AFORESAID TO DISENGAGE SAID VEHICLE CLUTCH IN RESPONSE TO OPERATOR-OPERATION OF SAID OPERATOR MEMBER.