Patent ID: RE40539

Claim:
A fluid dispensing pump comprising: a feed screw having a helical cavity defined between a major diameter and a minor diameter of a thread of the feed screw; a cartridge body , the cartridge body and the feed screw comprising a detachable cartridge unit, the cartridge unit having a feed port in communication with the feed screw for introduction of dispensing fluids into the helical cavity; and a pump housing including a cartridge cavity, the cartridge cavity having a mounting location at which the cartridge unit including both the cartridge body and the feed screw is inserted into and removed from the cartridge cavity, the pump housing releasibly securing the cartridge unit in the cartridge cavity, the cartridge unit having a motor interface at a first end of the cartridge unit and a fluid outlet and a second end of the cartridge unit opposite the first end, the cartridge unit including a fluid path between the feed port and the fluid outlet; a closed-loop servo-motor , the servo- motor having indexed rotational positions for controlling rotational position of the feed screw during a dispensing operation , the servo- motor including a rotary encoder that generates a data signal related to the rotational position of the feed screw, and the motor interface of the cartridge unit being releasably coupled to the servo - motor when the cartridge unit is inserted into the cartridge cavity; and a motor controller that receives the rotational position data signal from the encoder, and, in response, transmits a control signal to the servo - motor for controlling the rotary position and rotational velocity of the feed screw during a dispensing operation, to control a flow of dispensing fluid in the fluid path through the feed port to the fluid outlet during the dispensing operation .