Patent ID: 7395954

Claim:
A pneumatic nail gun comprising: a gun body having an immovable cylinder therein, a hitting piston being disposed in the cylinder, the hitting piston dividing the cylinder into a top chamber and a bottom chamber, a main air housing collecting compressed high pressure air with a constant pressure, and a trigger at one end of the main air housing driving the high pressure air to hit a nail; at least one main passage disposed at a peripheral portion of the cylinder or a side of the main air housing, the at least one main passage having a valve bolt therein to divide the main passage into a top passage, a middle valve chamber, and a bottom passage, the top passage and the middle valve chamber being connected with the main air housing for introducing and gathering high pressure air therein, the middle valve chamber being connected with the bottom passage via a main valve opening, the valve bolt being capable of controlling the opening and closing of the main valve opening; and a sleeve valve disposed between the bottom passage and the main air housing, to open and close fluid communication from the bottom chamber to atmosphere, wherein before the piston hitting the nails, the high pressure air in the top passage drives the valve bolt downwardly to move to close the main valve opening to close the fluid communication between the middle valve chamber and the bottom passage, and the high pressure air in the main air housing drives the sleeve valve to move upwardly to open the fluid communication from the bottom chamber to the atmosphere, when the piston hits the nails and before the reposition, the high pressure air in the top passage is discharged to make the high pressure air in the middle valve chamber to drive the valve bolt upwardly such that the valve bolt moves to open the main valve opening for guiding the high pressure in the main air housing continuously into the bottom passage via the middle valve chamber, moving the sleeve valve downwardly to close the fluid communication from the bottom chamber to the atmosphere for gathering the high pressure air in the bottom chamber to rapidly drive the piston to upwardly move to reposit, when the piston reposits, the valve bolt moves down to close the main valve opening.