Patent ID: 7384249
Filing Date: 2008-06-10
Classification: G01F

Abstract:
1. A fluid metering system, comprising: a housing including a piston chamber with first and second spaced ends, at least one housing inlet passage, and at least one housing outlet passage, said housing inlet and outlet passages communicating with said piston chamber; a piston in said piston chamber, said piston having first and second ends and an outer surface; said piston reciprocally movable within said piston chamber, between said first and second ends of said piston chamber, to alternatingly define first and second volumes within said piston chamber adjacent said first and second ends of said piston, respectively; at least one longitudinally extending first slot formed on said outer surface of said piston and extending from said first end of said piston toward said second end of said piston, said first slot having an opening at said first end of said piston in communication with said first volume; at least one longitudinally extending second slot formed on said outer surface of said piston and extending from said second end of said piston toward said first end of said piston, said second slot having an opening at said second end of said piston in communication with said second volume; said piston rotatable within said piston chamber to alternatingly bring one of said first and second slots in registration with said housing inlet passage, and to simultaneously bring the other of said first and second slots in registration with said housing outlet passage, whereby fluid is dispensed from one of said first and second volumes of said piston chamber through said housing outlet passage as said piston moves toward the other of said first and second ends of said piston chamber; a rotary actuator operatively coupled to said piston and configured to rotate said piston to alternatingly register one of said first and second slots with said housing inlet passage, while simultaneously registering the other of said first and second slots with said housing outlet passage; a piston rod extending from said first end of said piston, said piston coupled to said rotary actuator by said piston rod; and a compensator rod extending from said second end of said piston, said compensator rod sized to have substantially the same volume as said piston rod such that the maximum values of said first and second volumes are substantially equal; wherein said housing inlet passage is adapted to be in communication with a source of pressurized fluid and said piston is actuated for reciprocating movement within said piston chamber by said pressurized fluid acting on said piston through one of said first and second slots when said slot is in registration with said housing inlet passage.