Patent ID: 7341174

Claim:
A pneumatic nail gun comprising: a gun body having a movable cylinder installed therein, a head valve integrally formed or disposed on the top of the cylinder, a hitting piston disposed in the cylinder to divide the cylinder into a top cylinder chamber and a bottom cylinder chamber; a main air housing accumulating compressed air at a high pressure to drive the hitting piston to downwardly move to hit nails and to upwardly move to reposit; a main passage formed at a peripheral portion or a side of the movable cylinder, having a valve bolt installed therein to divide the main passage into a top passage, a middle valve chamber, and a bottom passage; a top through hole connected between the top passage and the main air housing to guide the high pressure air into the top passage for accumulation; a bottom through hole connected between the middle valve chamber and the main air housing to guide the high pressure air into the middle valve chamber for accumulation; and a main valve opening formed between the middle valve chamber and the bottom passage, to be opened or closed under the controlling of the valve bolt, wherein before the piston hitting the nails, the high pressure air in the top passage drives the valve bolt to downwardly move to close the main valve opening so that air communication between the middle valve chamber and the bottom passage is closed, when the piston hitting the nails and before repositing, 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 to upwardly move to open the main valve opening for guiding the high pressure in the main air housing into the bottom cylinder chamber via the middle valve chamber and the bottom passage so that the piston is driven to upwardly move, and after the piston reposited, the valve bolt moves down to close the main valve opening.