Importance

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Abstract

A fastener driving tool powered by internal combustion of an air/fuel mixture. The tool body contains connected upper and lower coaxial cylinders. The upper cylinder is provided with a piston assembly and is connected by a one-way valve to a combustion air chamber. The lower cylinder contains a piston/driver assembly and is surrounded by and connected to a return air chamber. The upper cylinder piston assembly and the lower cylinder piston/driver assembly, when in their normal unactuated positions, define therebetween a combustion chamber provided with an ignition device. A positive trigger-actuated cam system, upon actuation of the trigger, is configured to open a fuel valve to introduce a measured amount of gaseous fuel from a source thereof into the combustion chamber; to thereafter open an air valve to introduce a measured quantity of air from the combustion air chamber into the combustion chamber; to next actuate the ignition device to combust the aire fuel mixture causing the lower cylinder piston/driver assembly to drive a fastener and to fill the return air chamber with air under pressure in the upper cylinder piston assembly to replenish air under pressure in the combustion air chamber; and finally to actuate a control valve operating an exhaust valve eliminating products of combustion enabling the upper cylinder piston assembly to return to its normal position and air from the return air chamber to return the lower cylinder piston/driver assembly to its normal position.

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First Claim