US Patent 10010224 Variable output pump for foam dispensing system

An exemplary refill unit for a foam dispenser includes a container for holding foamable liquid and a liquid pump. The liquid pump includes a pump housing and an outlet nozzle with an elongated central axis. The pump housing has an arcuate shaped liquid pump chamber formed by a backing plate. The backing plate includes a liquid inlet and a flexible membrane. At least a portion of the elongated central axis of the nozzle extends through a central area defined, at least in part, by the arcuate shaped pump chamber.