Patent ID: 9239033
Filing Date: 2016-01-19
CPC Classification: F02M

Claim Text:
1. A fuel vapor treatment system for introducing a fuel vapor generated in a fuel tank into an internal combustion engine, comprising: a purge passage connecting the fuel tank and an intake passage through which an intake air is introduced into the internal combustion engine; a canister provided in the purge passage for adsorbing a part of the fuel vapor flowing through the purge passage; a purge valve provided in the purge passage between the canister and the intake passage for opening and closing the purge passage; a first pump passage of which one end is connected to the canister; a second pump passage of which one end is capable of being connected to another end of the first pump passage; an electric pump connected to another end of the second pump passage for pressurizing or depressurizing an interior of the fuel tank through the second pump passage, the first pump passage, the canister and the purge passage; a first atmospheric passage of which one end is connected to the pump and another end is opened to an atmosphere; a second atmospheric passage of which one end is connected to the first atmospheric passage; a selector valve provided between another end of the first pump passage, one end of the second pump passage, and another end of the second atmospheric passage, the selector valve switching a passage connection between a first position in which the first pump passage is connected to the second pump passage and a second position in which the first pump passage is connected to the second atmospheric passage; a pressure detector detecting a pressure in the second pump passage; a control unit controlling operations of the purge valve, the pump, and the selector valve; an orifice passage connecting the first pump passage and the second pump passage; and an orifice provided in the orifice passage, wherein: the control unit includes: a fuel-vapor-leak determining portion which determines whether a fuel vapor leak from the fuel tank is in an allowable range based on a reference pressure detected by the pressure detector in a condition where the selector valve connects the first pump passage and the second atmospheric passage and the pump is driven in order to pressurize or depressurize the interior of the fuel tank; a fuel purge portion which introduces the fuel vapor adsorbed by the canister into the internal combustion engine through the intake passage by opening the purge valve; and a foreign matter removing portion which controls the selector valve to connect the first pump passage and the second pump passage so as to circulate an atmospheric air in the pump while the fuel purge portion introduces the fuel vapor into the internal combustion engine, the control unit determines a time point at which the foreign matter removing portion starts its operation based on a variation of the reference pressure, the control unit compulsorily operates the fuel purge portion and the foreign matter removing portion based on a variation of the reference pressure.