| 摘要 |
<p>A cutting-off tool, e.g. a chainsaw, has an i.c. engine 11 located in a housing. Carburettor 35 supplies fuel/air mixture to the engine. The carburettor is connected through induction port 36 to the clean air side 34 of an air filter 37, and sucks fuel from a fuel-filled control chamber 33. The fuel enters this chamber from tank 10 through pipe 27, pump 29, and inlet valve 32, which is controlled by diaphragm 31. This diaphragm defines a compensation chamber 20, which is connected by compensation line 21 to the clean air side of the air filter. This reduces fuel supply proportionately to reduced air supply as the air filter becomes clogged. Tank 10 is also connected by line 8 and throttle 4 to overflow reservoir 9. Rather than opening air valve 17 to atmosphere, it is connected by pipe 15 to compensation line 21. As fuel vapour does not escape to atmosphere, fire risk is reduced.</p> |
