Handheld work apparatus having an air-cooled combustion engine

摘要

A portable, handheld work apparatus such as a chain saw has a handle (5, 7) to guide the work apparatus (1) and has an air-cooled, mixture-lubricated combustion engine (10) arranged in a casing as a drive for a work tool (3). The cylinder (11) has a combustion chamber (13) formed therein to which an air/fuel mixture is supplied. The air/fuel mixture is ignited by a spark plug (23) which projects into the combustion chamber (13). An ignition control (30) triggers a spark in dependence on the angular position of the crankshaft (15). A temperature sensor (35, 45, 55) is provided to control the cylinder temperature. The temperature signal of the temperature sensor (35, 45, 55) is connected to a power control (40). When a predetermined temperature is exceeded, the power control (40) changes the operating parameters of the combustion engine (10) in such a manner that the power of the combustion engine (10) is changed.

主权项

1. A hand-held work apparatus having a work tool, the work apparatus comprising:
a handle to guide said work apparatus; a casing; an air cooled, single cylinder two-stroke combustion engine having operating parameters; said combustion engine being arranged in said casing and being configured to drive said work tool; said engine including a piston and an air-cooled cylinder having a combustion chamber delimited by said piston; said combustion engine being a mixture lubricated engine and including a cooling blower for generating a cooling air flow for cooling said air-cooled cylinder of said combustion engine; said crankcase being configured to permit fuel to be supplied thereto so as to ensure a complete mixture lubrication; said combustion chamber being configured to be supplied with an air/fuel mixture; said engine further including a crankcase; a crankshaft mounted in said crankcase; said crankshaft being configured to be driven by said piston and to drive said work tool with a driving power developed by said engine; an ignition control; a spark plug projecting into said combustion chamber and being controlled by said ignition control to trigger an ignition spark in dependence on the rpm and the angular position of said crankshaft to ignite said air/fuel mixture; a fuel metering device for supplying fuel; a throttle flap configured to have a position coordinated with the amount of fuel supplied by said fuel metering device; an intake channel having a flow cross section which can be set in dependence upon the position of said throttle flap; a temperature sensor configured to directly or indirectly measure an operating temperature of said combustion engine and outputting a temperature signal of said combustion engine in dependence upon said operating temperature; a power control of said combustion engine; said temperature sensor being connected to said power control for transmitting said temperature signal of said combustion engine thereto; and, said power control being configured to adjust said operating parameters of said combustion engine when said operating temperature reaches a pregiven temperature limit value of said combustion engine to effect a reduction of said driving power of said engine in order to reduce heat input and therewith to change the temperature of said combustion engine and to so actively control said operating temperature of said combustion engine.