Electronic positive displacement fluid pump with motor cooling and air purging

A positive displacement fluid pump comprising:

• a housing defining an internal cavity;
• a motor having a drive shaft that rotates about an axis, the motor being housed within the internal cavity of the housing;
• an internal plate adjacent the motor and including a central bore through which the drive shaft extends;
• an external plate including an inlet in fluid communication with a suction port and an outlet in fluid communication with a delivery port;
• a pumping ring sandwiched between the internal and external plates;
• and
• a pumping arrangement rotatably coupled to the drive shaft such that rotation of the pumping arrangement by the drive shaft causes fluid to be pumped from the suction port to the delivery port, the pumping arrangement being located within the pumping ring and axially between the internal plate and the external plate, wherein
• the internal plate includes an inwardly-facing face surface, an opposite outwardly-facing face surface, and a complementary delivery port formed in the outwardly-facing face surface and in fluid communication with the delivery port of the external plate, and
• the internal plate further includes a fill passage connected to the complementary delivery port, the fill passage extending to the inwardly-facing face surface of the internal plate and being in fluid communication with the internal cavity of the housing, wherein fluid pumped by the pumping arrangement is delivered to the internal cavity of the housing through the fill passage.