| 摘要 |
The present invention relates to a compression spring fluid motor for reciprocating a fluid injection pump to inject predetermined doses of secondary fluid into a primary fluid stream. The motor is comprised of a housing which has a primary fluid inlet and outlet. A stepped piston is provided which has a large face and A smaller face. The piston is mounted for reciprocation in the housing and separates the interior into at least first and second variable chambers. A valve unit is carried by the piston and is shiftable for establishing a stroke cycle of the piston by alternating the closing of one face of the piston and at the same time opening the other face of the piston to pressurized fluid. An actuator rod is fixed to the housing and extends axially and centrally into the piston and is cooperable with an operator unit for alternately shifting the valve unit at the top and bottom of the operating cycle of the piston, whereby pressurized primary fluid alternately operates on the large and small faces of the piston to reciprocate the piston when pressurized fluid is supplied to the inlet of the motor housing.
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