Piezoelectric pump with vibrating plate, protrusion and valve arrangement

A pump comprising:

• a vibrating plate;
• a piezoelectric body connected to a first main surface of the vibrating plate;
• a cover including a top plate and a side wall,
• the top plate facing a second main surface of the vibrating plate, which is on the opposite side from the first main surface of the vibrating plate,
• the top plate having an opening part, and
• the side wall being connected to an outer peripheral portion of the top plate so as to surround a space between the top plate and the vibrating plate;
• a support portion connected to the side wall and supports an outer periphery of the vibrating plate;
• a valve fixed to the top plate or the vibrating plate and disposed within said space between the top plate and the vibrating plate, said valve being positioned outside the opening part of the top plate when viewed in a direction parallel to the first main surface of the vibrating plate;
• an opening between the side wall and the vibrating plate;
• and
• a protrusion on any one out of the top plate, the side wall, and the vibrating plate so as to protrude into the space;
• wherein the protrusion is in between the opening part of the top plate and the side wall in a cross section viewed in a direction parallel to the second main surface of the vibrating plate.