A compressor includes a thrust force adjusting part which is configured to adjusts a thrust force between a back surface of a disc part in an impeller and a casing. The thrust force adjusting part includes an outer sealing part which seals a gap between the back surface and the casing, an inner sealing part which seals the gap at a position away inward in a radial direction, and a throttle formation part which has a throttle part in which the gap in an axial direction is formed to be narrowed inward in the radial direction. An outer space sandwiched by the outer sealing part and the inner sealing part and an inner space sandwiched by the inner sealing part and the throttle part are formed the gap. The width of the throttle part is narrower than the width of the inner space.
1. A compressor, comprising:
a rotary shaft which is configured to rotate about an axis;
impellers which have a disc part rotating together with the rotary shaft;
a casing which covers the rotary shaft and the impellers; and
a thrust force adjusting part which is configured to adjust a thrust force in an axial direction in which the axis extends between a back surface of the disc part facing one side in the axial direction and the casing,
wherein the thrust force adjusting part includes:
an outer sealing part which seals a gap between the back surface and the casing;
an inner sealing part which is disposed at a position away from the outer sealing part inward in a radial direction centered on the axis and seals the gap between the back surface and the casing; and
a throttle formation part which has a throttle part in which the gap between the back surface and the casing in the axial direction is formed to be narrowed and formed at a position away from the inner sealing part inward in the radial direction,
an outer space sandwiched by the outer sealing part and the inner sealing part and an inner space sandwiched by the inner sealing part and the throttle part are formed in the gap between the back surface and the casing,
a width of the throttle part in the axial direction is narrower than a width of the inner space in the axial direction,
the impellers have two convex parts that protrude from the back surface and are integrally formed with the disc part,
the outer sealing part and the inner sealing part each seal a corresponding gap in the radial direction between seal surfaces of the convex parts formed parallel to an outer surface of the rotary shaft and the casing,
the throttle formation part has a protrusion part which protrudes toward the back surface from the casing inward the radial direction with respect to the two convex parts,
a volume of the inner space is formed to be same as a volume of the outer space,
only the two convex parts protrude from the back surface, and
the throttle part is formed such that when the gap in the throttle part is narrowed, an amount of leakage from the inner space decreases, and when the gap in the throttle part is widened, the amount of leakage from the inner space increases.
2. The compressor according to claim 1 , wherein the back surface has an inclined surface inclined with respect to the axial direction is provided in a region facing at least one of the outer space and the inner space.
3. The compressor according to claim 1 , further comprising:
a motor which is configured to output a rotational driving force to the rotary shaft; and
a motor cooler which is configured to supply a gas flowing out from the inner space via the throttle part to the motor.
4. The compressor according to claim 1 , wherein
the impellers include a first impeller and a second impeller which is disposed to face a side opposite to the first impeller in the axial direction and is configured to compress a working fluid compressed using the first impeller, and
the thrust force adjusting part is provided on the first impeller and the second impeller.
5. The compressor according to claim 1 , further comprising:
an external gas introduction part through which a gas for increasing a pressure in the outer space is introduced from the outside into the outer space.
6. The compressor according to claim 2 , further comprising:
a motor which is configured to output a rotational driving force to the rotary shaft; and
a motor cooler which is configured to supply a gas flowing out from the inner space via the throttle part to the motor.
7. The compressor according to claim 2 , wherein
the impellers include a first impeller and a second impeller which is disposed to face a side opposite to the first impeller in the axial direction and is configured to compress a working fluid compressed using the first impeller, and
the thrust force adjusting part is provided on the first impeller and the second impeller.
8. The compressor according to claim 3 , wherein
the impellers include a first impeller and a second impeller which is disposed to face a side opposite to the first impeller in the axial direction and is configured to compress a working fluid compressed using the first impeller, and
the thrust force adjusting part is provided on the first impeller and the second impeller.