Fluid dispenser device with bellows

A fluid dispenser device including a body and at least one individual reservoir containing a single dose of dispersible substance, opening means being provided for opening an individual reservoir each time the device is actuated, the device including an inhalation piece and an inhalation trigger system that comprises a deformable air chamber that co-operates with said inhalation piece, and a trigger element that co-operates with said air chamber, such that during inhalation through said inhalation piece, said air chamber is deformed and said trigger element actuates said opening means, so that a reservoir is opened by said opening means, said air chamber is a hollow pouch comprising:

• a deformable side body;
• an open first end including a peripheral edge that surrounds an opening forming an inlet of said hollow pouch;
• and a second end forming a bottom of said hollow pouch;
• said second end including connection means for connecting said air chamber to said trigger element, said side body being in the form of a bellows comprising a plurality of bellows portions arranged axially one after another, wherein said bellows in the side body comprises bellows portions having outside diameters that are different and having inside diameters that are different, wherein a first one of the bellows portions adjacent to said opening has a maximum outside diameter that is smaller than a maximum outside diameter of a second one of the bellows portions adjacent to said first one of the bellows portions.