Valve spring, pump, dispensing unit and dispenser

A pump for a product wherein the pump comprises:

• a pump housing, a piston, a pump chamber, an inlet, an outlet, an inlet valve and an outlet valve,
• wherein the piston is axially movable and configured to convey the product via the inlet into the pump chamber and out of the pump chamber to the outlet,
• wherein the outlet valve has a valve spring made of plastic configured to pretension a valve stem against a valve seat of a dispensing unit which is configured to dispense the product, wherein the valve spring comprises a plurality of spring elements arranged axially one behind the other, wherein each spring element of the plurality of spring elements has two curved portions which are formed mirror-symmetrically with respect to one another and are connected to one another at their ends, wherein said two curved portions of a spring element are arranged mirror-symmetrically with respect to a mirror plane that runs transversely or perpendicularly to the axis, wherein said two curved portions of a spring element are each curved away from the respective mirror plane, so that a distance between the two portions of a spring element decreases with increasing distance from the axis, and
• wherein two adjacent spring elements are each connected to one another by a connecting piece.