US Patent 9814346 Infusion unit for a coffee machine

An infusion unit having a closing piston, an infusion cylinder, and an ejection piston (for ejecting spent coffee). The piston can slide inside the infusion cylinder, between a retracted position and an extended position, for ejection of the spent coffee. Operation of the ejection piston can involve an oscillating rocker having a first arm (for driving the ejection piston) and a second arm (for engaging the oscillating movement of the rocker). The oscillating rocker can involve a first control cam arranged to generate oscillation in a direction driving toward the extended position of the ejection piston, or a second control cam arranged to generate oscillation in a direction driving toward the retracted position of the ejection piston.