Patent · US Active

Handheld work apparatus having a control unit for an electric heating element

US8833322B2 · kind B2 · utility

1Cited by

4References

9Claims

0Family size

Assignee

Andreas Stihl AG & Co. KG · DE

Inventors

Heinrich Leufen · Schwaikheim, DE
Jörg Präger · Winnenden, DE
David Fallscheer · Echterdingen, DE
Rolf Walter · Waiblingen, DE
Michael Link · Esslingen am Neckar, DE

Key dates

Filing date	Nov 17, 2011
Grant date	Sep 16, 2014
Priority date	—
Expiry date	Nov 17, 2031

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY02T10/12
WIPO fieldEngines, pumps, turbines
WIPO sectorMechanical engineering

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.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.