Patent ID: 8701946

Claim:
A material dispensing pump comprising: a closed-loop servo-motor having indexed rotational positions; a dispensing controller that generates control signals to control the servo-motor, wherein the servo-motor performs a dispensing operation in response to the control signals; a housing having an opening; a removable cartridge assembly positioned in the opening, the cartridge assembly having a cavity, an inlet port, an outlet port in communication with the cavity, and a feed mechanism extending through the cavity, the feed mechanism including a cylindrical neck and a feed path, the feed path being substantially sealed from ambient air between the inlet port and the outlet port by a seal positioned about the neck between the neck and the cartridge assembly and a threaded spanner nut that applies pressure in a direction along a longitudinal axis of the neck and that retains the seal in position about the neck, wherein the seal substantially seals the feed path from ambient air, the closed-loop servo-motor driving the feed mechanism during the dispensing operation; a pressure unit for applying positive pressure to cause material to be presented to the inlet port at a desired rate during the dispensing operation such that the material flows through the feed path toward the outlet port; and a material suspension unit for placing the material in the substantially sealed feed path in suspension following the dispensing operation.