Diesel Injector Fuel Injector 0445110418 Bosch for FIAT Ducato, Iveco Daily

There are many reasons for valve fracture: such as deep quenching; Material cracks; Improper material; Lock groove transition arc is too small; Valve welding strength is not enough. This paper only deals with valve cracking caused by installation, improper use and other non-quality reasons.

Valve fracture caused by impact (excluding valve impact piston caused by incorrect valve phase)

The top dead center of valve motion stroke is constant in the whole process of diesel engine operation, and its bottom dead center changes slightly in different working conditions.

At idle or medium speed, due to the action of valve spring, the gap between the valve rocker arm shaft and the rocker arm shaft hole exists above the shaft. The eccentricity of the rocker arm rotation center relative to the rocker arm shaft is equal to the gap between the rocker arm shaft and the shaft hole. At high speed operation, due to the action of the valve rocker arm, push rod and tasht inertial force, the valve reaches the moment of bottom dead center, the eccentricity of the rocker arm rotation center and the rocker arm shaft And the total runout of the center of rotation of the rocker arm is 2 times of the clearance between the hole of the rocker arm and the shaft. Then the downward shift of valve bottom dead center is about 4.4 ~ 5.6 times of rocker arm shaft clearance. Whereas the existing small and medium-sized diesel engines in our country are mainly between 0.06 and 0.10 mm, the statistics suggest that the displacement of valve is about 0.05 mm during high speed operation.