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US 5,133,329 AGranted
Ignition system for combustion-powered tool
AssigneeIllinois Tool Works Inc.
InventorsWilliam G. Rodseth, Ernest J. Wendling
Life of this patent
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AssigneeIllinois Tool Works Inc.
InventorsWilliam G. Rodseth, Ernest J. Wendling
Estimating the term…
For a combustion-powered tool, an ignition system is powered by a battery and is arranged so that a sudden discharge of a capacitor, as charged via an oscillator, produces a spark at a spark gap of a spark plug, so that the oscillator is enabled if a trigger switch is closed while a head switch is closed, but not if the trigger switch is closed while the head switch is opened, and if a battery voltage, as monitored, is not less than a reference voltage, and so that a silicon-controlled rectifier, which is arranged to produce a sudden discharge of the capacitor, is switched to a conductive state if the capacitor voltage, as monitored, and is not less than a reference voltage. The head and trigger switches, which are photoelectric, are polled intermittently to determine whether they are closed. Predominantly, solid-state components are used.
For a combustion-powered tool, an ignition system comprising a battery, two normally opened switches connected to the battery, namely a head switch and a trigger switch, means powered by the battery for producing ignition, and switch-monitoring means for monitoring the head and trigger switches, for enabling the ignition-producing means if the trigger switch is closed while the head switch is closed, and for disabling the ignition-producing means if the trigger switch is closed while the head switch is opened or if both switches are opened.
Dependencies are inferred from the claim text.