Patent ID: 7712647

Claim:
A driving machine using compressed air as a power source, comprising: a cylinder; a piston fitted into the cylinder such that it can be reciprocated; a driver connected to the piston; a bumper provided on the bottom portion of the cylinder; a housing disposed to cover the cylinder from outside and including therein a pressure storage chamber for storing compressed air; a return air chamber formed in the outer periphery of the cylinder for storing the return compressed air that is used to move up and return the piston; an exhaust port, after the piston is returned, for discharging compressed air existing downwardly of the piston to the air; a fastening member feed piston movable backward or movable forward by supplying the compressed air of the return air chamber from the passage hole of the return air chamber through an air passage into the fastening member feed cylinder or by discharging such compressed air from the fastening member feed cylinder; a return spring for energizing the fastening member feed piston in one direction; and a feed pawl mounted on the leading end of the fastening member feed piston, wherein, within the air passage formed between the return air chamber and the fastening member feed cylinder, there is formed a filter portion, and in the vicinity of the leading end of the projection-shaped portion of the filter portion, there is formed the passage hole.