Abstract: The analysis showed that most often in Russia and in the CIS countries the failure of the electrohydraulic nozzle is observed due to the loss of the hydraulic tightness of its shut-off valve. As a result of check valves experimental studies, it was found that one groove is formed in (40%) of cases and in the remaining two or more are formed. Studies confirm that the valve seat of the electrohydraulic injector is a 3D hardened part and has the same hardness at the entire depth. Lapping of the valve seat surface does not weaken the hardness in the contact area and therefore, cannot cause a decrease in the post-repair life. For the repair of valve seats, the repair technology of autotractor and combine electrohydraulic diesel engines Bosch with injector of common rail type by hardening of the shut-off valve seat is considered. Two methods of valve seat hardening: electric-spark hardening and the spraying of titanium nitride were compared. The first method is cost effective but the second method has advantages in hardness and surface quality and therefore has a greater operational life. The hardening of valve seats by electro-spark machining with VK8 electrode and spraying with titanium nitride increases the hardness by 2.2 and 2.7 times, respectively, compared with the new valve seats which may indicate a proportional increase in wear resistance in abrasion. In general, the studies have shown the possibility of using hardening operations when repairing electrohydraulic injectors.
I.I. Gabitov, R.N. Saifullin, M.N. Farhshatov, A.V. Negovora1, S.G. Mudarisov, E.R. Khasanov, R.R. Galiullin, F.Z. Gabdrafikov, N.M. Yunusbaev and A.R. Valiev, 2018. Hardening of Electrohydraulic Injectors Valve Units of Diesels at Repair. Journal of Engineering and Applied Sciences, 13: 6478-6486.