Rear drive EGR pump

An exhaust gas recirculation pump for an internal combustion engine comprising:

• an electric motor assembly including an electric motor disposed within an electric motor housing, the electric motor housing including a coolant passageway;
• a roots device coupled to the electric motor, the roots device including a roots device housing defining an internal volume;
• two rotors disposed in the internal volume, one of the two rotors being connected to the electric motor;
• an insulated coupling joining a rotor shaft to an electric motor shaft, and
• a transmission assembly including a drive gear attached to the rotor coupled to the electric motor, the transmission assembly including a driven gear meshed with the drive gear, the driven gear coupled to the other rotor of the two rotors, wherein the transmission assembly is positioned on an opposing side of the roots device housing relative to the electric motor;
• wherein the roots device housing includes a coolant cavity at least partially surrounding a first set of bearings of the rotors, the first set of bearings supporting the rotors, and wherein the coolant cavity is in fluid communication with the coolant passageway of the electric motor housing;
• wherein the insulated coupling includes a pair of separated extending tapered members formed on the electric motor shaft, wherein the insulated coupling includes a rotor shaft coupling including a circular body that is attached to the rotor shaft and a pair of separated extending tapered members extending from the circular body, wherein the insulated coupling includes a connector linking the extending tapered members of the rotor shaft and the electric motor shaft, the connector including a central circular body having tapered bodies formed radially about a perimeter, wherein the tapered bodies of the connector define openings into which the extending tapered members of the rotor shaft and the electric motor shaft are positioned to couple the rotor shaft and the electric motor shaft.