The present invention relates generally to diagnosis methods for solenoid valves and common rail fuel injection systems for diesel engines. More particularly, the invention relates to a method of diagnosing a solenoid valve employed in a commonrail fuel injection system for a diesel engine.
However, even without electrical failures, the SCVs still cannot normally operate when there exist mechanical failures or abnormalities in the SCVs. For example, when foreign matters flow into the SCVs along with fuel, they may cause the SCVs tobe locked, thus making it impossible to suitably control the amount of pressurized fuel supplied from the fuel supply unit to the common rail.
Furthermore, in some cases, running the engine under a high-flow condition may temporary recover the locked SCV to normal and thus no any additional measure is taken. However, in other flow conditions, the SCV may be easily locked again, thussignificantly impairing the drivability of a vehicle that employs the common rail fuel injection system.
The solenoid valve includes a housing with a first and a second seat formed therein, a moving member configured to be moved in the housing, and a solenoid. The solenoid valve is configured to fully open with the moving member resting on thefirst seat when the solenoid is energized and fully close with the moving member resting on the second seat when the solenoid is deenergized.
when the energizing and deenergizing causes collisions of the moving member against at least one of the first and second seats in the solenoid valve and noises are thus generated by the collisions, detecting occurrence intervals of the noises;and According to a further implementation of the diagnosis method, when each cycle of the energizing and deenergizing causes two of the noises, the solenoid valve is diagnosed as being in normal condition; when each cycle of the energizing anddeenergizing causes only one of the noises, the solenoid valve is diagnosed as being in semi-locked condition; and when there is no noise caused by the energizing and deenergizing, the solenoid valve is diagnosed as being in fully-locked condition.
