The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 07, 1997
Filed:
Nov. 10, 1994
James E Doherty, Barrington, IL (US);
Stanley C Veoukas, Wheeling, IL (US);
Ernest J Wendling, Algonquin, IL (US);
Illinois Tool Works Inc., Glenview, IL (US);
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. The voltage divider also includes a permanently grounded resistance, two selectively groundable resistances, and two photoelectric switches, each including a phototransmissive diode and a photoreceptive transistor and being arranged to ground one of the selectively groundable resistances if a fastener between the phototransmissive diode and the photoreceptive transistor blocks phototransmission therebetween but not if the fastener does not block phototransmission therebetween. The photoelectric switches can thus be used for discriminating among relatively short, intermediate-length, and relatively long fasteners.