US Patent 8388323 Reagent dosing pump

A pump is provided for pumping a liquid. The pump includes an inlet, an outlet, and a pumping chamber for receiving the liquid from the inlet. An actuator arrangement is also included and is operable between a first position and a second position to pump the liquid from the pumping chamber into the outlet and includes a solenoid actuator having a solenoid coil, a pole element, and a coil former to carry the solenoid coil. The inlet and the pumping chamber are in fluid communication with a supply passage when the actuator arrangement is in the first position. The supply passage extends into or around the solenoid coil and is defined between the coil former and the pole element to allow transfer of heat from the actuator arrangement.