| 摘要 |
A direct action fluid motor and injection pump is disclosed which injects small quantities of a second fluid into a primary fluid stream. A housing has an inlet and an outlet connected to a primary fluid conduit. The housing contains a stepped piston which reciprocates in response to the fluid pressure applied alternately to the closed small and large face of the piston. A valve set alternately closes one and opens the other of the faces. A valve positioner carried with the piston is held in alternate stable positions by cooperating springs on the valve positioner and a post in the piston. Stop members are located above and below the piston travel, each associated with an actuating spring. The valve positioner is preshifted at the end of the stroke, using the full force of the piston, by stop members to move the valve positioner and valve set to an intermediate unstable position. When the closed valves on the closed face are unseated a small distance, a relatively weak actuating spring can then fully shift the valve positioner and valves to change the direction of reciprocation. The injection pump has a pump casing connected in sealed contact with the motor housing and has an outlet leading to the secondary fluid. A reciprocating pump mechanism connected to the piston has a selectively adjustable sliding valve member which closes the pump chamber at a plurality of predetermined positions of the pump mechanism. The pump mechanism displaces fluid from the pump chamber without sliding seals. Displaced secondary fluid travels under pressure through a control passage to mix with primary fluid at the outlet of the pump housing. The pump casing is quickly and easily removable for access to the pump mechanism to rapidly adjust the ratio of secondary fluid. The pump self primes automatically with primary fluid, if needed, at the bottom of its stroke.
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