  Brownian motors and Feymann ratchets have been intensively studied in the
past decades due to their significance to the foundation of statistical
physics. In this work we propose a new type of Brownian motor, i.e., a
self-driven motor that only utilizes the temperature difference inside and
outside the motor. The motor is a container with asymmetric geometry; when
filling of gas, directional motion occurs if its temperature is different from
the environment. The essentially new mechanism is that the asymmetric geometry
of the container may induce anisotropic thermalization, which results in a
density gradient and propels the motor. The directional motion ceases untill
the density gradient disappears as the inside temperature approaches the
environment temperature. The same mechanism is also applied to design
self-driven rotators. Possible experimental realizations are discussed.
