Pump module, discharge head and fluid dispenser

A discharge head for a liquid dispenser, comprising

• a base for attachment to a liquid reservoir;
• an applicator unit having a discharge opening, said applicator unit being displaceable relative to the base in a pumping movement;
• and
• the pump module comprising:
• a pump cylinder having a fluid inlet at one end and an inlet valve;
• a stem and a piston attached to the stem, the piston being located within the pump cylinder and defining a pump chamber together with the pump cylinder, the stem eztending out of the pump cylinder and comprising an outlet channel of the pump module, the stem and the piston being movable relative to the pump cylinder from an unactuated end position with a maximum volume of the pump chamber to an actuated end position with a minimum volume of the pump chamber in order to press fluid out of the pump chamber into the outlet channel;
• a return spring in the form of a bellows spring or a dome-shaped spring by which return spring the stem and the piston are pressed in the direction of the unactuated end position, the bellows spring or the dome-shaped spring being supported with a first end surface by the stem of a support collar fixedly attached to the stem and being supported with a second end surface by the pump cylinder or a support collar fixedly attached to the pump cylinder;
• and
• a ventilation path, through which ventilation path an interior space of the bellows spring of the dome-shaped spring is connected to a surrounding atmosphere, said ventilation path running at least partially through at least one ventilation aperture or at least one end-side recess in the bellows spring or the dome-shaped spring and/or through at least one ventilation channel or at least one ventilation groove in the support collar attached to the pump cylinder.

A fluid dispenser for dispensing a fluid product, the fluid dispenser comprising:

• a fluid reservoir;
• and
• a discharge head comprising a pump module, the pump module comprising:
• a pump cylinder having a fluid inlet at one end and an inlet valve;
• a stem and a piston attached to the stem, the piston being located within the pump cylinder and defining a pump chamber together with the pump cylinder, the stem extending out of the pump cylinder and comprising an outlet channel of the pump module, the stem and the piston being movable relative to the pump cylinder from an unactuated end position with a maximum volume of the pump chamber to an actuated end position with a minimum volume of the pump chamber in order to press fluid out of the pump chamber into the outlet channel;
• a return spring in the form of a bellows spring of a dome-shaped spring by which return spring the stem and the piston are pressed in the direction of the unactuated end position, the bellows spring or the dome-shaped spring being supported with a first end surface by the stem or a support collar fixedly attached to the stem and being supported with a second and surface by the pump cylinder or a support collar fixedly attached to the pump cylinder;
• and
• a ventilation path, through which ventilation path an interior space of the bellows spring or the dome-shaped spring is connected to a surrounding atmosphere, said ventilation path running at least partially through at least one ventilation aperture or at least one end-side recess in the bellows spring or the dome-shaped spring and/or through at least one ventilation channel or at least one ventilation groove in the support collar attached to the pump cylinder.