Abstract: A piston velocity control and stability control system is provided for a combustion powered tool having a self contained combustion engine. The system includes a ring that may be adjusted relative to exit ports in a cylinder of the combustion engine. The ring includes openings which may be incrementally aligned between a completely exposed, and a substantially closed position relative to the exit ports. Displaced air volume within the cylinder exits through the exit ports as a piston advances down the cylinder, and the velocity of the piston will be greatest when the exit ports are completely exposed. User initiated reduction of the effective size of the exit ports by adjustment of the ring will reduce piston velocity as described per application. A nosepiece used to guide the driver blade and position the blade over a fastener is isolated from the cylinder so that the nosepiece remains stable relative to the workpiece upon combustion and until the driver blade strikes the fastener.

Abstract: A piston velocity control and stability control system is provided for a combustion powered tool having a self contained combustion engine. The system includes a ring that may be adjusted relative to exit ports in a cylinder of the combustion engine. The ring includes openings which may be incrementally aligned between a completely exposed, and a substantially closed position relative to the exit ports. Displaced air volume within the cylinder exits through the exit ports as a piston advances down the cylinder, and the velocity of the piston will be greatest when the exit ports are completely exposed. User initiated reduction of the effective size of the exit ports by adjustment of the ring will reduce piston velocity as described per application. A nosepiece used to guide the driver blade and position the blade over a fastener is isolated from the cylinder so that the nosepiece remains stable relative to the workpiece upon combustion and until the driver blade strikes the fastener.

Abstract: A system for controlling the energy output of a combustion-powered, fastener-driving tool in which a fan is arranged to produce turbulence in a combustion chamber when the fan is driven, in which a direct current motor is arranged to drive the fan when a driving voltage is applied across the motor, and in which a battery provides a battery voltage not less than the driving voltage. A voltage divider includes a settable resistance, either a potentiometer or two parallel, fixed resistances that can be alternatively selected, and is used to provide a setpoint voltage. A comparator, an inverter, and a transistor switch are arranged to sample a voltage proportional to the rotational speed of the fan, to compare the sampled voltage to the setpoint voltage, to apply the driving voltage across the motor if the sampled voltage is less than the setpoint voltage, and to remove the driving voltage from across the motor if the sampled voltage is not less than the setpoint voltage.

Abstract: For a combustion-powered, fastener-driving tool, a combined ignition and fuel system comprises a battery, two normally opened switches connected to the battery, namely a head switch and a trigger switch, a fuel injector including a solenoid and an associated circuit controlling the fuel injector to enable the fuel injector to inject a combustible fuel for a first time interval, a circuit for producing ignition, and a circuit for monitoring the head and trigger switches, for disabling the injector-controlling circuit if the trigger switch is closed while the head switch is opened or if both switches are opened, for enabling the solenoid if the trigger switch is closed while the head switch is closed, for enabling the ignition-producing circuit after a second time interval succeeding the first time interval, and for disabling the ignition-producing circuit when the injector-controlling circuit is disabled as mentioned.