Air compressor structure

An air compressor structure, comprising:

• a cylinder, having a plurality of air holes;
• a piston, reciprocally coupled in the cylinder;
• a cover, assembled to the cylinder, the cover having a column, wherein an internal space of the cylinder and an internal space of the cover are connected through the plurality of air holes;
• and
• an anti-return piece, movably disposed between the cylinder and the cover,
• wherein when the piston performs a first stroke, the piston moves close to the plurality of air holes to compress air in the cylinder, the compressed air passing through the plurality of air holes and lifting the anti-return piece to flow into the cover, and
• wherein when the piston performs a second stroke, a vacuum is formed in the cylinder as soon as the piston moves away from the plurality of air holes, and the anti-return piece is driven by the vacuum and the compressed air in the cover to cover and seal the plurality of air holes,
• wherein the anti-return piece has a bowl-shaped profile, and the cylinder further has a partition and a limit ring extending from the partition, wherein a bowl edge of the bowl-shaped profile abuts an inner annular wall of the limit ring during the second stroke, the column is adapted to abut an inner bowl bottom of the bowl-shaped profile during the first stroke, and the partition has the plurality of air holes,
• wherein the anti-return piece has at least one annular rib located at an outer bowl bottom of the bowl-shaped profile, the at least one annular rib forming a recess on the outer bowl bottom with the bowl edge due to a step difference in between the at least one annular rib and the bowl edge,
• wherein the recess faces away from the column and faces toward a junction of the limit ring and the partition.