Patent ID: 7775194

Claim:
An automatic residual fuel vent device for a carburetor in an engine equipped with a float type carburetor to which fuel within a breather-equipped fuel tank (TF) is supplied via a changeover cock (CO), the automatic residual fuel vent device comprising: a fuel supply passage ( 15 ) connecting a bottom part of the fuel tank (TF) and a float chamber ( 10 ) of a carburetor (CA); a negative pressure passage ( 17 ) connecting a negative pressure generating part of an engine (E) and a negative pressure operating chamber ( 53 ) of a diaphragm pump (PD); a fuel vent passage ( 16 ) connecting a bottom part of the float chamber ( 10 ) of the carburetor (CA) and an upper part of the fuel tank (TF); a single changeover cock (CO) provided so as to straddle the fuel supply passage ( 15 ) and the negative pressure passage ( 17 ) and selectively changing over between providing or blocking communication of the fuel supply passage ( 15 ), providing or blocking communication of the negative pressure passage ( 17 ), and providing or blocking communication of the negative pressure passage ( 17 ) with the atmosphere; a negative pressure surge tank (TS) provided in the negative pressure passage ( 17 ) between the negative pressure generating part of the engine (E) and the changeover cock (CO); and the diaphragm pump (PD), which is connected partway along the fuel vent passage ( 16 ) and is operated by negative pressure of the negative pressure surge tank (TS); fuel within the fuel tank (TF) being supplied to the float chamber ( 10 ) based on control of changeover of the single changeover cock (CO), and residual fuel of the float chamber ( 10 ) being drawn up by the diaphragm pump (PD) operated by negative pressure accumulated within the negative pressure surge tank (TS) and being returned to the fuel tank (TF).