Method for requirement-based servicing of an injector
A method for requirement-based servicing of an injector in a common-rail system in which, during ongoing operation of the engine, a current operating point is stored as a function of the rail pressure and of the fuel injection mass, and the current operating point is multiplied by a damage factor and is stored as a reference injection cycle as a function of the rail pressure as well as of the fuel injection mass. A total reference injection cycle is calculated by forming sums over the reference injection cycles, and a load factor is calculated as a function of the total reference injection cycle and the permissible injection cycles, and the load factor is set as decisive for the servicing recommendation of the injector.
1. A method for requirement-based servicing of an injector in a common rail system of an engine, comprising the steps of:
a) providing a first characteristic diagram of injection cycles, which contains reference points that represent a load spectrum of a frequency of an operating point within rail pressure-injection mass classes, each of the reference points being a value representing a number of injection cycles as a function of rail pressure and fuel injection mass during operation of the engine;
b) providing a second characteristic diagram for a damage factor that describes hydrodynamic loading on the common rail system, the second characteristic diagram being pre-populated, the second characteristic diagram having the same reference points of the rail pressure and to the fuel injection mass as the first characteristic diagram;
c) determining a current operating point by measuring the rail pressure and the fuel engine mass and locating a corresponding reference point value on the first characteristic diagram;
d) reading out a reference point value from the second characteristic diagram that corresponds to the reference point on the first characteristic diagram;
e) calculating a reference injection cycle value by multiplying the reference point value of the current operating point by the corresponding reference point value from the second characteristic diagram to provide a corresponding reference point saved on a third characteristic diagram of reference injection cycles as a function of the rail pressure and the fuel injection mass;
f) repeating steps c)-e) to complete the third characteristic diagram;
g) calculating a total reference injection cycle value by adding up the reference injection cycle values;
h) calculating a load factor by dividing the total reference injection cycle value by a predetermined value of permitted injection cycles; and
i) setting the load factor as decisive for a servicing recommendation of the injector.
2. The method according to claim 1 , further including comparing the load factor with a limiting value, and calculating a remaining time margin and generating a servicing recommendation to replace the injector when the limiting value is exceeded.
3. The method according to claim 2 , including predicting a remaining running time for continued operation when the limiting value is undershot.
4. The method according to claim 1 , wherein the damage factor is additionally weighted as a function of fuel temperature.
5. The method according to claim 1 , wherein the damage factor characteristic diagram is populated with data from back-measured field engines.