Turbo-machine having bellows unit for automatic axial thrust control

A turbo-machine, comprising:

• a volute casing defining therein a fluid passage for forming a fluid pressure;
• a rotating shaft provided in the volute casing so as to be rotatable;
• an impeller coupled to one end of the rotating shaft to draw fluid using centrifugal force generated by rotation;
• seals provided around front and rear ends of the impeller to prevent leakage of the fluid;
• an axial thrust control member installed in the volute casing behind the impeller with respect to a flowing direction of the fluid, the axial thrust control member having an annular planar shape, with a plurality of ribs provided on one surface of the axial thrust control member facing the flowing direction of the fluid such that portions of the ribs are exposed from the surface of the axial thrust control member to impede rotation of the fluid;
• and
• a bellows unit, comprising:
• a piston having an annular planar shape, the piston installed in the volute casing in a shape surrounding a circumferential outer surface of the axial thrust control member;
• and a bellows connected with one surface of the piston, the bellows having the predetermined elasticity;
• and an internal space, between the piston and the volute casing, isolated from the fluid drawn behind the impeller,
• wherein the bellows unit is constructed such that the bellows is compressed by pressure of the fluid drawn into the volute casing, the piston moves by a predetermined distance along the axial direction and thus the resistant force of the rib impeding the rotation of the fluid is increased.