  We report the discovery of three new substellar companions to solar-type
stars, HD191806, HD214823, and HD221585, based on radial velocity measurements
obtained at the Haute-Provence Observatory. Data from the SOPHIE spectrograph
are combined with observations acquired with its predecessor, ELODIE, to detect
and characterise the orbital parameters of three new gaseous giant and brown
dwarf candidates. Additionally, we combine SOPHIE data with velocities obtained
at the Lick Observatory to improve the parameters of an already known giant
planet companion, HD16175 b. Thanks to the use of different instruments, the
data sets of all four targets span more than ten years. Zero-point offsets
between instruments are dealt with using Bayesian priors to incorporate the
information we possess on the SOPHIE/ELODIE offset based on previous studies.
  The reported companions have orbital periods between three and five years and
minimum masses between 1.6 Mjup and 19 Mjup. Additionally, we find that the
star HD191806 is experiencing a secular acceleration of over 11 \ms\ per year,
potentially due to an additional stellar or substellar companion. A search for
the astrometric signature of these companions was carried out using Hipparcos
data. No orbit was detected, but a significant upper limit to the companion
mass can be set for HD221585, whose companion must be substellar.
  With the exception of HD191806 b, the companions are located within the
habitable zone of their host star. Therefore, satellites orbiting these objects
could be a propitious place for life to develop.
