Infinite families of directed strongly regular graphs using equitable partitions

In this paper we introduce a new construction of directed strongly regular graphs (briefly DSRGs) from smaller ones. With its aid each suitable equitable partition in a single DSRG leads to an infinite family of DSRGs. We construct dozens of infinite families in this way. As a byproduct, we confirm the existence of DSRGs for 29 previously open parameter sets of orders at most 110.