How to Detect and Evaluate the Performance of Bosch Truck Injectors

From: http://www.sinocmpinjector.com/

1. Whether the injection volume is accurate

According to the opening degree of the accelerator pedal, the amount of fuel injection is adjusted in time, which is the basic principle of the electronic control system. In order to achieve a good state of the engine's power performance, emissions performance, comfort performance, etc. the accuracy of the injector's fuel injection under different working conditions is very high. Generally, it is measured in mm3/stroke, that is, one-thousandth of a milliliter per injection.
There are several ways to assess the accuracy of the injection volume:
1) Static injection point
2) Dynamic injection curve
3) Spray repeatability, is standard deviation

2. Whether the leakage amount and functional oil return is normal

The leakage amount refers to the amount of oil that the high-pressure oil leaks into the low-pressure oil passage through the gap of each mechanical component. There are six main locations inside the CRIN injector, as shown in the following figure.
Functional oil return refers to the amount of oil that the injector returns from the high pressure oil passage to the low pressure oil passage to achieve its own injection performance. It is mainly returned to the armature by the valve seat control chamber through the seat of the valve seat when the injector ball valve is open. The amount of oil in the low pressure oil circuit around the assembly. During the after-sales test, the oil return (leakage + functional return) at the full load point is usually used as the assessment point.

3. Whether the jet delay is normal

The injection delay is the time interval between the start of energization of the electromagnet and the injection of fuel from the injector, typically between 300 and 800 microseconds. The level of rail pressure, the performance of the electromagnet, and the kinematics of each moving part will affect the jet delay.

4. Whether the spray atomization effect is good

The atomization effect of the fuel injection directly affects the combustion condition of the diesel oil and thus affects the working performance of the engine. The reason why the high pressure common rail system uses high pressure injection is to achieve a good atomization effect. Therefore, the level of rail pressure directly affects the atomization effect. In addition, the shape of the nozzle hole and the surface condition of the nozzle wall surface have a significant influence on the atomization effect (such as mechanical damage of the nozzle hole, surface erosion of the nozzle hole surface, particle wear, etc.).
It can be seen from the performance of the above Bosch truck injector that the performance of the injector is closely related to each component. Failure  of any component may cause the injector to lose effect as a whole, so during the maintenance process of injector, it is necessary to carry out systematic detection of each couple of injectors to find out the real cause of the fault, so as to eliminate them one by one and realize the maintenance effect and normal operation of the injector as soon as possible.