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:
Sep. 16, 2014
Filed:
Nov. 17, 2011
Heinrich Leufen, Schwaikheim, DE;
Jörg Präger, Winnenden, DE;
David Fallscheer, Filderstadt, DE;
Rolf Walter, Waiblingen, DE;
Michael Link, Ostfildern, DE;
Heinrich Leufen, Schwaikheim, DE;
Jörg Präger, Winnenden, DE;
David Fallscheer, Filderstadt, DE;
Rolf Walter, Waiblingen, DE;
Michael Link, Ostfildern, DE;
Andreas Stihl AG & Co. KG, Waiblingen, DE;
Abstract
A portable work apparatus has a combustion engine for driving a work tool. An air/fuel mixture is supplied to the engine via a carburetor which is provided with an electrical heating element for heating to a given temperature. The heating element is connected to a switch via which electrical energy, which is provided by a generator driven by the engine, is supplied. When a given temperature is exceeded, the switch interrupts the energy supply. To achieve an exact temperature control, the ohmic resistance value of the heating element is stored in a memory in dependence on the temperature. The current flowing through the heating element and the voltage drop at the heating element are measured and the instantaneous resistance of the heating element is calculated therefrom. This calculated value is compared to the value stored in the memory to open or close the switch in dependence on the comparison.