  Chiral edge state (CES) at zero magnetic field has already been realized in
the magnetically doped topological insulator (TI). However, this scheme
strongly relies on material breakthroughs, and in fact, most of the TIs cannot
be driven into a Chern insulator in this way. Here, we propose to achieve the
CESs in 2D TI/ferromagnetic insulator/TI sandwiched structures through
spin-selective coupling between the helical edge states of the two TIs. Due to
this coupling, the edge states of one spin channel are gapped and those of the
other spin channel remain almost gapless, so that the helical edge states of
each isolated TI are changed into the CESs. Such CESs can be hopefully achieved
in all TI materials, which are immune to magnetic-disorder-induced
backscattering. We propose to implement our scheme in the van der Waals
heterostructures between monolayer 1T'-WTe$_2$ and bilayer CrI$_3$. The
electrical control of magnetism in bilayer CrI$_3$ switches the transport
direction of the CESs, which can realize a low-consumption transistor.
