Timer

Claim 1

A piston pump adapted to pump measured fluid volumes at selected time intervals, comprising, in combination, a pump chamber having a fluid-pumping plunger reciprocably movable therein; pump drive means including an electric motor operatively associated with the plunger for reciprocably moving the plunger within the pump chamber, to draw fluid into the pump chamber and pump it out; a timer having a plurality of selectable timing intervals; a timer switch actuated by the timer to open and close the electric circuit to the pump drive means at a selected time interval to initiate a stroke of the plunger; a pump drive switch in parallel to the timer switch, to open and close the electric circuit to the pump drive means; and pump drive switch actuating means associated with the pump drive means to open the pump drive switch whenever the plunger is in a starting position and turn off the pump drive means, and to close the pump drive switch whenever the timer switch closes and starts operation of the pump drive means; the pump drive switch remaining in the closed position until the plunger returns to the starting position; the timer switch overriding the pump drive switch to start the pump drive means only at the starting position for a stroke of the plunger, and the timer and pump drive switches together thereby controlling the plunger operation stroke by stroke, to control the fluid volume delivered per time interval according to the number of strokes per time interval.