Fuel-filter malfunction detection device

摘要

A fuel-filter malfunction detection device detects a clogging of a fuel filter when specified conditions are satisfied. In a clogging detection, a command discharge quantity to a high-pressure pump is increased more than a total of a fuel injection quantity and a leakage of the fuel supply system while a pressure-reducing valve is closed. When the fuel filter is clogged, a discharge quantity of the high-pressure pump is decreased relative to the command discharge quantity and a differential pressure is generated between an estimated common-rail pressure and an actual common-rail pressure. When an integrated moving average of the averages of the differential pressure is greater than or equal to a specified value, an ECU determines that the fuel filter has a malfunction. Then, a malfunction flag is turned ON.

主权项

1. A fuel-filter malfunction detection device applied to a fuel supply system which is provided with a high-pressure pump pressurizing a fuel which will be supplied to a fuel injector of an internal combustion engine, a fuel filter arranged upstream of the high-pressure pump for removing a foreign matter from the fuel, a common-rail accumulating the fuel pressurized by the high-pressure pump for supplying the fuel to the fuel injector, and a pressure sensor arranged downstream of the high-pressure pump for detecting a pressure of the fuel which will be supplied to the fuel injector, the fuel-filter malfunction detection condition device comprising:
a discharge control portion increasing or decreasing a discharge quantity of the high-pressure pump when a specified malfunction detection condition is established; a pressure obtaining portion obtaining a fuel pressure which the pressure sensor detects; a malfunction determination portion determining whether the fuel filter has a malfunction based on the fuel pressure obtained by the pressure obtaining portion, when the discharge control portion increases or decreases the discharge quantity of the high-pressure pump with a specified malfunction detection condition established; a pressure decreasing portion decreasing the pressure in the common-rail after the pressure obtaining portion obtains the fuel pressure from the pressure sensor; and a pressure-reducing valve decreasing a fuel pressure in the common-rail, wherein the discharge control portion increases the discharge quantity of the high-pressure pump when the specified malfunction detection condition is established, when a pressure differential pressure between an estimated fuel pressure and an actual fuel pressure is greater than or equal to a specified pressure in a case that the discharge control portion increases the discharge quantity of the high-pressure pump, the malfunction determination portion determines that the fuel filter has a malfunction, the pressure decreasing portion closes the pressure-reducing valve when the discharge control means increases the discharge amount of the high-pressure pump when the specified malfunction detection condition is established, and, the pressure decreasing portions opens the pressure-reducing valve to decrease the fuel pressure in the common-rail when the pressure obtaining means obtains the fuel pressure.