| 摘要 |
A portable working machine comprising a tool unit ( 1 ) with a disc guard and a circular, disc-shaped tool ( 3 ), which can be rotated about an axis of rotation ( 4 ), which is horizontal in the normal upraised position of the machine, and a machine unit ( 2 ), which includes at least a filter system ( 10 ), which is at least partly accommodated in a top part of the machine unit, an internal combustion engine ( 11 ) with an engine cylinder ( 13 ) with bore ( 12 ) having a centre line ( 30 ), a crankshaft ( 14 ) and a crankcase ( 15 ), as assembly ( 16 ) comprising members for supplying air and fuel to the engine, a fuel tank ( 17 ), a muffler ( 18 ) with an entrance port ( 46 ) provided in the rear side ( 42 ) of the muffler and facing an exhaust port ( 47 ) of the cylinder ( 13 ), i.e. the muffler is directly mounted to the cylinder, handles ( 19, 20 ), controls ( 21, 22 ) and preferably supports ( 23, 24 ) on the underside of the machine unit for allowing upright positioning of the machine on a flat ground, and a power transmission between the machine unit and the tool unit. Especially the cylinder bore ( 12 ) is inclined forwards in a direction towards the tool unit, such that the centre line ( 30 ) of the cylinder bore forms a tilt angle (alpha) larger than zero, in said direction, to a perpendicular to any or both of the following lines: a) a base line ( 33 ), which is a line coinciding with a horizontal surface on which the machine is resting in an upright position, when said supports on the underside of the machine unit contact said surface, and b) a tangential line ( 33 ') extending from a peripheral point of the tool, on the lower part of the tool when the machine has an upright position, to the bottom side of a rear support ( 24 ) of the machine unit.
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