Common Rail Fuel Injector Control Valve Assembly F00VC01386 for Injectors 0445110387 & 0445110388

Transient states analysis of CI engine injectors with the use of optical methods  (PART 7)

For both injectors the hardware response delay is considered as constant and it is 0.012 ms for piezo- and 0.016 for solenoid injector. As the diode light signal occurs on the same frame after the start of each measurement, it could be stated that the measurements are stable and repeatable. Figure 5 presents short energizing time for both types of injectors, as was already mentioned in the research methodology. This time amounts to 0.2 ms and 0.3 ms for piezo- and solenoid injector, respectively.

On the chart for piezo-injector, the trend to speed up the injection with higher pressure in the chamber was presented. Only for Pinj = 60 MPa this tendency is different, but it could be influenced by random circumstances. The solenoid injector was working in a more repeatable manner and the back-pressure did not make any significant difference in the delay time. In that case the injection pressure was the factor which speeded up the injection, as it was already observed for piezo-injector. What’s worth mentioning is the fact, that the results for solenoid injector from Pinj over 60 MPa in most cases differ by ±1 frame only, so in terms of the measurement accuracy they should be treated as no difference. Piezo-injector at low injection pressures obtained lower delay than electro-injector, but with the increase in pressure that was reversed. It should be noted that a piezo-injector is an older design: the electromagnetic injector replaced the piezo-injector in the manufacturer designs.

The results of the injection delay for medium and long injection durations are presented in figure 6 and figure 7, respectively. The piezo-injector operation could be evaluated as more random. On the basis of the results comparison it could be stated, that air pressure (back-pressure) has most significant influence on the delay and the influence of fuel pressure is marginal. Very similar results were achieved for solenoid injectors, but in this case the greatest influence on the injection delay had the fuel pressure and the influence of air pressure was negligible.