Patent ID: 6644252
Filing Date: 2003-11-11
Classification: F02B,F02D,F02M

Abstract:
A two-stroke engine as a drive motor in a hand-held working tool, the two-stroke engine comprising:a cylinder (2) and a reciprocating piston (5) arranged in the cylinder (2), wherein the reciprocating piston (5) delimits a combustion chamber (3) within the cylinder (2); a crankshaft (7) rotatably supported in a crankcase (4); a connecting rod (6) connected to the reciprocating piston (5) and the crankshaft (7), wherein the piston (5) drives the crankshaft (7) via the connecting rod (6); wherein the cylinder (2) has an outlet (10) for removing exhaust gases from the combustion chamber (3) and a cylinder intake (11) supplying a fresh mixture into the combustion chamber (3); a storage duct (14) having a first end (13) formed by the cylinder intake (11) and having a second end (15) opening into the crankcase (4); a first mixture forming device (8a) for forming a fuel/air mixture having a first mixture-forming channel (28); a second mixture forming device (8b) having a second mixture-forming channel (17); wherein the first mixture-forming channel (28) is connected to the storage duct (14) between the first and second ends (13, 15); wherein the crankcase (4) comprises a crankcase intake (16), connected to the second mixture-forming channel (17), for taking in combustion air and fuel; a first fuel path (41) opening into the first mixture-forming channel (28) and a second fuel path (31) opening into the second mixture-forming channel (17); a transfer passage (18) having a first end, connected to the combustion chamber (3) and having a transfer window (19) opening into the combustion chamber (3), and a second end (20) connected to the crankcase (4); wherein the first mixture-forming channel (28) leading to the storage duct (14) has a flow cross-section (d) that is smaller by more than one half than a flow cross-section (D) of the second mixture-forming channel (17) leading to the crankcase intake (16); and wherein, during idle of the internal combustion engine (1), the second fuel path (31) opening into the second mixture-forming channel (17) is substantially completely closed and fuel, required for operation, is supplied substantially exclusively via the first mixture-forming channel (28) leading to the storage duct (14).