PURPOSE: To prevent performance of a compressor from being deteriorated by oil agitation loss caused by rotation by setting the proper amount of a balance weight made of a member whose density is different from a shaft material at a position which is eccentrically in the shaft of a rotary shaft.
CONSTITUTION: A balance weight 101 made of a material whose density is larger than the material of the rotary shaft 5 is buried in the bottom end of a rotary shaft at a position which is eccentrically in the rotary shaft 5. The hole (hollow hole) 103 which is unbalance is drilled/opened on at the top end of the rotary shaft 5 and in the eccentric position inside the shaft. A shaft longitudinal direction distance between the mass, the volume, the eccentric amount, the shaft system gravity of the balance weight 101 and a balance gravity is decided on the basis of the material of the rotary shaft 5 and the density of the material of the balance weight 101. Since the balance weight 101 is provided in a hollow shape in the rotary shaft 5, it is not exist as a parts (the number of the parts is not increased), and a working time is no more requirement to set them.
HIRABAYASHI MASASHI
HIROOKA KATSUMI
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