Patent ID: 6167874
Filing Date: 2001-01-02
Classification: F01M,F02B

Abstract:
A portable handheld work apparatus including a motor-driven chain saw, cutoff machine, hedge trimmer, blower apparatus, brushcutter, the portable handheld work apparatus comprising: a work tool; an internal combustion engine for driving said work tool; said engine including: a cylinder; a piston movably mounted in said cylinder; said cylinder and said piston conjointly delimiting a combustion chamber; said cylinder having an intake opening and an intake valve for opening and closing said intake opening; said cylinder having an exhaust opening and an exhaust valve for opening and closing said exhaust opening; a valve housing connected to said cylinder; said intake valve and said exhaust valve movably mounted in said valve housing; a crankcase connected to said cylinder and communicating with said valve housing; a crankshaft rotatably journalled in said crankcase; a connecting rod interconnecting said piston and said crankshaft; said piston reciprocating in said cylinder to rotatingly drive said crankshaft via said connecting rod and alternately generate an overpressure and an underpressure in said crankcase; a valve drive assembly driven by said crankshaft for actuating said intake valve and said exhaust valve; a mixture-preparation device for supplying an air/fuel lubricant mixture; an intake channel conducting said mixture to said intake valve and said combustion chamber; means for charging said valve drive assembly and said valve housing with at least a portion of said air/fuel lubricant mixture in response to said overpressure and underpressure; and, said engine being a short stroke engine having a stroke/bore ratio of less than 0.8.