Internal combustion engine

US4958602A · kind A · utility

Assignee

• Andreas Stihl AG & Co. KG · DE

Inventors

• Klaus Hoppner · Erbach, DE
• Reinhard Friedrich · Waiblingen, DE
• Hermann Weiss · Hamburg, DE

Key dates

• Filing date: Oct 20, 1989
• Grant date: Sep 25, 1990
• Expiry date: Oct 20, 2009

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F05C2251/042
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

The invention relates to internal combustion engines and especially to two-stroke engines for portable handheld work tools such as motor-driven chain saws or the like. Material made of light metal alloys is used in two-stroke engines for portable handheld tools in order to save weight. Thus, the crankshaft bearing is made of steel while the bearing covers holding the bearing are made of a magnesium alloy. Heating causes the bearing cover to expand by an amount greater than the crankshaft bearing whereby the press fit of the crankshaft bearing can become endangered and, in an extreme case, a clearance can develop between the crankshaft bearing and the bearing cover. According to the invention, the press fit between the crankshaft bearing and the bearing cover is maintained by placing a plastic annular segment therebetween having a thermal expansion coefficient so selected that it compensates for the different thermal expansions of the bearing cover and the bearing.