초록 ▼

A leak detection apparatus for an evaporative emission control system is provided. By the apparatus, a current through a motor driven air pump is detected and determined as a judgment level when the air pump is ON and a directional control valve is in a position of connecting a fresh air inlet of a

A leak detection apparatus for an evaporative emission control system is provided. By the apparatus, a current through a motor driven air pump is detected and determined as a judgment level when the air pump is ON and a directional control valve is in a position of connecting a fresh air inlet of a canister to an atmospheric vent, for thereby allowing air from the air pump to pass through a reference orifice of a bypass conduit and thereafter be released to the open air through the directional control valve. Then, it is established a condition in which the air pump is ON and the directional control valve is in a position of connecting the fresh air inlet to an outlet of the air pump so that air from the air pump passes through the directional control valve and the fresh air inlet of the canister and is supplied to the purge line, and this condition is maintained for a predetermined time. The predetermined time is made shorter as the temperature of fuel detected by a fuel temperature sensor is higher and a tank residual detected by a tank residual sensor is larger. At a measurement timing after lapse of the predetermined time, the current through the air pump is measured and determined as a leak level. When the leak level is lower than the judgment level, it is determined that a leak is present in the evaporative emission control system, i.e., a leak is present in a fuel vapor flow passage extending from a fuel tank to a purge control valve by way of the canister. A method of detecting a leak in an evaporative emission control system is also provided.

대표청구항 ▼

[ What is claimed is:] [1.] An apparatus for detecting a leak in an evaporative emission control system including a fuel vapor flow passage which extends from a fuel tank to a purge control valve by way of a canister, the apparatus comprising:a device for defining an atmospheric vent in communicatio

[ What is claimed is:] [1.] An apparatus for detecting a leak in an evaporative emission control system including a fuel vapor flow passage which extends from a fuel tank to a purge control valve by way of a canister, the apparatus comprising:a device for defining an atmospheric vent in communication with the open air;a motor driven air pump having an outlet;a directional control valve for connecting said fresh air vent selectively to one of said atmospheric vent and said outlet of said air pump;a bypass conduit providing communication between a fresh air inlet of said canister and said outlet of said air pump while bypassing said directional control valve, said bypass conduit having a reference orifice;means for detecting a first current through said air pump when said air pump is CN and said directional control valve is in a position of connecting said fresh air inlet to said atmospheric vent;means for detecting a second current through said air pump after lapse of a predetermined time from establishment of a condition in which said air pump is ON and said directional control valve is in a position of connecting said fresh air inlet to said outlet of said air pump;means for comparing said second current with said first current and judging if a leak is present in said fuel vapor flow passage;means for detecting a temperature of fuel in said fuel tank; andmeans for determining said predetermined time variably on the basis of said temperature of fuel.