Patent ID: 8850873

Claim:
An evaporated fuel leak detecting apparatus that detects a leak of fuel evaporated in a fuel tank storing fuel to be supplied to an internal combustion engine by generating a pressure difference between an inside and an outside of the fuel tank, the apparatus comprising: an ignition switch of the combustion engine; a main passage communicating with the fuel tank; a detection passage configured to communicate with the main passage; an atmospheric passage having a first end configured to communicate with the main passage and a second end released to atmospheric air; a switch valve that selectively switches the main passage to communicate with the detection passage or the atmospheric passage; a pressure controlling portion disposed in the detection passage, the pressure controlling portion compressing or decompressing inside of the fuel tank when the switch valve causes the main passage to communicate with the detection passage; a passage valve disposed in the main passage to allow or prohibit a communication between the fuel tank and the switch valve, the passage valve outputting a signal corresponding to a communication state between the fuel tank and the switch valve; a bypass passage causing the main passage to communicate with the detection passage by bypassing the switch valve; a throttle arranged in the bypass passage; a first detector detecting a pressure in the detection passage and outputting a signal corresponding to the pressure detected in the detection passage; a second detector detecting a pressure in the fuel tank and outputting a signal corresponding to the pressure detected in the fuel tank; a first determiner determining whether the pressure in the fuel tank is within a predetermined range based on the signal output from the second detector when the ignition switch is on; a second determiner determining whether the passage valve allows or prohibits the communication between the fuel tank and the switch valve, when the first determiner determines that the pressure in the fuel tank is within the predetermined range and when the ignition switch is on; a control unit that controls the pressure controlling portion based on a determination result of the first determiner and a determination result of the second determiner; and a leak determiner that determines whether the fuel tank has the leak of evaporated fuel based on the signal output from the first detector and the signal output from the second detector.