Patent ID: 7293684

Claim:
A pneumatic nail gun comprising: a gun body having a movable cylinder installed therein, 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 formed in the gun body for accumulating compressed air at a high pressure, a trigger valve being disposed at one end of the main air housing to be driven by a trigger disposed on the gun body to drive the hitting piston to downwardly move to hit nails and upwardly move to reposit; a head valve disposed on the top of the cylinder; a valve ring disposed on an outer wall of the cylinder so that a middle chamber is formed between the valve ring and an inner wall of the gun body to accumulate high pressure air therein, wherein before the trigger is pressed, the high pressure air pushes the cylinder to move upwardly to make the head valve close air communication between the main air housing and the top cylinder chamber, and when the trigger is pressed, the middle chamber discharges air and the cylinder moves downwardly driven by the high pressure air in the main air housing to make the head valve open the air communication between the main air housing and the top cylinder chamber so as to guide the high pressure air driving the piston to downwardly move to hit nails; and a return passage formed on the outer wall of the cylinder to drive the piston to upwardly move for reposition, which is connected between the main air housing and the bottom cylinder chamber and includes a valve bolt therein, wherein when the trigger is released, the valve bolt is driven by the high pressure air to open the return valve opening so that the high pressure air in the main air housing is guided to the bottom cylinder chamber to continuously drive the piston to rapidly move upwardly for reposition.