Patent ID: 6976457
Filing Date: 2005-12-20
Classification: F01L,F02B,F02F

Abstract:
1. A two-stroke engine including a two-stroke engine in a portable handheld work apparatus, the two-stroke engine comprising: a crankcase; a cylinder connected to said crankcase; said cylinder having a cylinder wall defining a cylinder bore open to said crankcase; a piston displaceably mounted in said cylinder bore and said piston and said cylinder conjointly defining a combustion chamber; a crankshaft rotatably mounted in said crankcase; said piston being operatively connected to said crankshaft for driving said crankshaft; a mixture inlet in said crankcase; a transfer channel for flow connecting said crankcase to said combustion chamber and said transfer channel having a first end open to said crankcase and a second end communicating with said combustion chamber; a bypass channel for conducting an essentially fuel-free gas; said bypass channel having an opening into said transfer channel at a location between said first and second ends thereof; said transfer channel being configured as a closed channel over the length thereof in said cylinder wall; a membrane valve assembly including a membrane axially inserted into said transfer channel through said first end thereof; said membrane having an attachment section and projecting in said transfer channel up to in front of said opening; said membrane being movable between a closed position wherein said opening is closed and an open position wherein said fuel-free gas can flow through said opening and into said transfer channel; said membrane valve assembly further including a membrane carrier for supporting said membrane in said open position thereof; and, said membrane being fixedly clamped at said attachment position thereof between said membrane carrier and said cylinder at the foot region thereof.