1991 Volume 77 Issue 6 Pages 840-847
Soft magnetic stainless steels are used for the yoke in fuel injectors to require a good corrosion resistance. The pulse response property of the yoke material is essential to the dynamical performance of fuel injectors. However, effects of alloying elements on the property is not clear.
An equipment measuring the pulse response property is devised to investigate various Fe-Cr-Al alloys including commercial magnetic stainless steels. The ring specimens used in the equipment are provided with a slit to simulate the injector system. The magnetic response to a magnetizing pulse current is measured so that the relaxation time can be obtained to estimate the pulse response property.
The results obtained show that the relaxation time mainly depends on the specific resistance of the alloy specimens. It decreases with the increase in the specific resistance, though the magnetic properties such as the coercive force are hardly affected. As a result, it has been found that a soft magnetic stainless steel of 10Cr-3Al composition is recommendable to the yoke material, better than 45Ni-permalloy or 12Cr-0.8Si-0.3Al stainless steel previously used.