Automatic oil pump, with a valved pumping piston and a valved driving piston unit

An automatic oil pump, comprising a drive chamber and an oil chamber installed on two sides of a main body, a front of the drive chamber having an inlet for compressed air, a rear of the oil chamber having an outlet for oil, a lower part of the main body connected to a sucking tube leading to the oil chamber, with the sucking tube having a one-way valve;

• a reciprocal driving device including a piston unit having oil seals on two sides thereof and a recess groove on an outside thereof intermediate the oil seals, with the piston unit being installed inside the drive chamber, a spring inside the drive chamber at a rear end of the piston unit and pushing against the piston unit;
• a driving rod attached to the rear end of the piston unit and that penetrates through the main body and into the oil chamber, grooves on an inside wall of the drive chamber and having a slightly larger width than the oil seals;
• a valve chamber at an inside center of the piston unit and having a movable post valve, with a valve gate at one end of the post valve capable of sealing a valve opening of the valve chamber;
• a piston part at another end of the post valve and located inside the valve chamber;
• opened channels on the piston unit at the valve opening and connecting two sides of the piston unit when the valve opening is opened;
• a first through hole on the piston unit and communicating between the recess groove and the valve chamber;
• a vent hole at a bottom of the drive chamber and communicating to outside of the main body;
• a pumping device including a hermetic cover, with the driving rod reaching into one end of the oil chamber and secured to the hermetic cover;
• a guide bolt attached to the hermetic cover opposite to the driving rod;
• a piston reciprocal on the guide bolt and having a side wall having an outer periphery in sealing contact with the oil chamber, with the side wall including through holes located spaced inwardly of the outer periphery and intermediate the outer periphery and the guide bolt, with the hermetic cover covering all through holes in the side wall of the piston;
• and a plurality of screw holes drilled on the wall of the drive chamber, each screw hole is inserted with a screw having an arched end defining the grooves on the inside wall of the drive chamber, thereby the piston unit of the reciprocal driving device drives the driving rod and the piston inside the oil chamber to move reciprocally, sucking oil continuously into and out of the oil chamber.