Analysis of working processes and efficiency assessment of hand-held power tools

Stephan Meyer, Armin Kölmel, Tim Gegg, Ute Dawin, Pascal Piecha, Alexander Trattner, Stephan Schmidt, Roland Kirchberger

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review


To date, different propulsion technologies are used in hand-held power tools. SI-engines in combination with a carburetor represent an appropriate propulsion solution for hand-held power tools. Depending on the requirements of the respective tool two- or four-stroke principle is applied. During the last years significant improvements regarding reductions of emissions have been achieved. Nevertheless, these tools have to be further improved in the near future in order to protect health and environment. Especially the shortage of fossil resources and the necessary reduction of carbon dioxide emissions ask for improved engine efficiency. Concurrently, customers demand for an easy usage with high performance at all operating conditions, e.g. varying ambient temperature and pressure.
In order to improve the working processes of these engines appropriate analysis methods are needed. Generally, the thermodynamic loss analysis is an useful tool to investigate working processes and is universally applicable. In the course of this paper several different series production engines (two- and four-stroke) are experimentally investigated on the test bench and the working processes are analyzed. A special topic for this segment of engines is the presence of scavenging losses of the delivered fuel. This publication considers the scavenging losses as a single efficiency loss within the thermodynamic loss analysis and a new calculation methodology is used for this. For this purpose a distinction between HC emissions from scavenging and combustion is necessary. Hence, the overall HC emissions have been experimentally analyzed with special measurement equipment regarding this distinction. Further, an approximation solution which is based on a standard exhaust gas measurement is compared to these results. Finally, the results of the thermodynamic loss analysis shows the respective causes of efficiency losses and strategies to improve the working processes can be derived from that.
Original languageEnglish
Publication statusPublished - 16 Mar 2016

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