Self contained internal combustion fastener driving tool

Abstract From the Canadian patent

A fastener driving tool powered by internal combustion of an air/fuel mixture. A tool body has located therein upper and lower coaxial cylinders containing upper and lower pistons, respectively attached to a common driver and forming a piston/driver assembly shiftable between a normal retracted position and an extended fastener driving position. A combustion chamber at the upper end of the lower cylinder and having an ignition device therein. The tool body contains a combustion air chamber and at least one return air chamber, together with a source of gaseous fuel. A trigger actuated control valve is configured to introduce a measured air/fuel mixture from the combustion air chamber and the …