Combined ignition and fuel system for combustion-powered tool

摘要

For a combustion-powered, fastener-driving tool, a combined ignition and fuel system (10) comprises a battery (12), two normally opened switches namely a head switch (14) and a trigger switch (16), a fuel injector (18) including a solenoid (20) and an associated circuit (22) controlling the fuel injector to enable the fuel injector to inject a combustible fuel for a first time interval, a circuit (24) for producing ignition, and a circuit (26) for monitoring the head and trigger switches (14, 16), for disabling the injector-controlling circuit (22) if the trigger switch (16) is closed while the head switch (14) is open or if both switches are open, for enabling the injector controlling circuit (22) if the trigger switch (16) is closed while the head switch (14) is closed, for enabling the ignition-producing circuit (24) after a second time interval succeeding the first time interval, and for disabling the ignition producing circuit (24) when the injector-controlling circuit (22) is disabled as mentioned. The system further comprises a circuit (60) for monitoring the battery voltage, for comparing the monitored voltage to a reference voltage, and for enabling the injector controlling circuit (22) and the ignition-producing circuit (24) if the monitored voltage is not less than the reference voltage, and for disabling the injector-controlling circuit (22) and the ignition-producing circuit (24) if the monitored voltage is less than the reference voltage.