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. 25, 1990
Filed:
Oct. 20, 1989
Andreas Stihl, Waiblingen, DE;
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.