Device for reducing evaporation loss from carburetors and fuel tanks

摘要

A lawn mower is illustrated as including a carburetor having a float bowl adapted to contain a vent assembly for selectively venting the air space of the carburetor float bowl to the atmosphere when the internal combustion engine of the lawn mower is running and for precluding evaporation of fuel from the air space when the engine is not running. The lawn mower fuel tank also includes a vent assembly for selectively venting the fuel tank to the atmosphere when the internal combustion engine is running and for precluding evaporation of fuel from the fuel tank into the atmosphere when the engine is not running. Each vent assembly includes a valve member resting on a valve seat and supported for movement in response to vibration of the engine and in such a manner that the valve member will return to its position on the valve seat when the engine is shut off.