  By using \emph{ab initio} calculations and symmetry analysis, we define a new
class of Weyl phonons, i.e., isolated Weyl phonons (IWPs), which are
characterized by Chern number $\pm$2 or $\pm$4 in their acoustic phononic
spectra and protected by the time inversion symmetry and point group
symmetries. More importantly, their particular topological feature make them
circumvent from the no-go theorem. Some high-symmetry points, behaving as
isolated Weyl points in the space groups (SGs) of the related phononic systems,
tend to form IWPs. As enumerated in Table I, the IWPs are located at the center
of three-dimensional Brillouin zone (BZ), and protected by the time-reversal
symmetry ($\cal T$) and the corresponding point group symmetries. Moreover, a
realistic chiral crystal material example of K$_2$Mg$_2$O$_3$ in SG 96, a
monopole IWP with Chern number -2 is found at the high-symmetry point $\Gamma$,
and in another material example of Nb$_3$Al$_2$N in SG 213, a monopole IWP with
Chern number +4 is confirmed at the point $\Gamma$. It is interesting that that
IWPs can not form the surface arcs in the surface BZ, which has not been
reported in the phononic systems to present. Our theoretical results not only
uncover a new class of Weyl phonons (IWPs), but also put forwards an effective
way to search the IWPs in spinless systems.
