The objective of this study was to determine changes in fuel delivery rate by common rail system injectors during their simulated operation on a test stand. Four Bosch injectors used, among others, in Fiat 1.3 Multijet engines were tested. The injectors were operated on a test rig at room temperature for 500 hours (more than 72 million work cycles). During the test, pressure and injection frequency were changed. Changes in the operating parameters were estimated based on obtained injection characteristics and effective flow area determined thereby. The observed changes in fuel delivery rate were compared with results of the surface analysis of control valves and nozzle needles. Despite the stated lack of wear, significant changes in the dynamics of injector operation were observed, particularly at short injection times. Small pilot injections cannot be corrected by the fuel injection control system because they do not affect the changes in torque; however, they do affect the combustion process. This creates conditions for increased emission of toxic exhaust components.
Nowadays, high-precision machines require lightweight materials with very high strength. Ion implantation is used to improve the mechanical strength of the material. A further paper presents the influence of manganese and nitrogen ion implantation on changes of microhardness of the surface layer of cobalt alloy. Samples were analyzed with the SEM-EDS Phenom ProX microscope. Microhardness was assessed with the Vickers method, and the loads of 1 gf (0.00981 N) and 5 gf (0.049 N) was applied using a FM-800 from Future-Tech microhardness meter. At a load of 1 gf, the penetration depth of the implanted specimens was reached not exceeding 0.5 um. At this depth, all samples showed an increase in microhardness compared to the unimplanted sample. The highest increase in microhardness was achieved after implantation of Mn ions with dose D=1∙1017 Mn+/cm2 and energy E=175 keV. The increased load on the indenter to 5 gf reduced the microhardness differences between implanted and unimplanted samples.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.