  The HARPS high-resolution high-accuracy spectrograph is offered to the
astronomical community since the second half of 2003. Since then, we have been
using this instrument for monitoring radial velocities of a large sample of
Solar-type stars (~1400 stars) in order to search for their possible low-mass
companions. Amongst the goals of our survey, one is to significantly increase
the number of detected extra-solar planets in a volume-limited sample to
improve our knowledge of their orbital elements distributions and thus obtain
better constraints for planet-formation models.
  In this paper, we present the HARPS radial-velocity data and orbital
solutions for 3 Solar-type stars: HD 100777, HD 190647, and HD 221287. The
radial-velocity data of HD 100777 is best explained by the presence of a 1.1
M_Jup planetary companion on a 384--day eccentric orbit (e=0.36). The orbital
fit obtained for the slightly evolved star HD 190647 reveals the presence of a
long-period (P=1038 d) 1.9 M_Jup planetary companion on a moderately eccentric
orbit (e=0.18). HD 221287 is hosting a 3.1 M_Jup planet on a 456--day orbit.
The shape of this orbit is not very well constrained because of our non-optimal
temporal coverage and because of the presence of abnormally large residuals. We
find clues for these large residuals to result from spectral line profile
variations probably induced by stellar activity related processes.
