| 摘要 |
PROBLEM TO BE SOLVED: To perform an effective cooling of a semi-closed motor without reducing a cooling capability and further prevent deterioration or damage of the stator of the semi-closed motor. SOLUTION: There is provided a semi-closed screw freezer comprising a condenser 2, an expansion valve 3, an evaporator 4 and a semi-closed screw compressor 1, wherein these components are connected by refrigerant passages 5, 6, 7 and 8. There is provided a super-cooling heat exchanger 18. There is also provided a space 1-7 for use in sealingly storing a motor 1-4 within a casing 1-1 of the semi-closed type screw compressor 1. Within the space 1-7 are provided an economizer gas passage 20 for feeding refrigerant having its heat absorbed by the super-cooling heat exchanger 18 through an electric valve 19 having a pulse motor for the economizer; a refrigerant gas passage 21 for connecting the space 1-7 to a tooth groove space of a screw rotor 1-2; a gas temperature sensor 22; and at least one of a coil temperature sensor or a discharged temperature sensor 13. The electric valve 19 having a pulse motor for the economizer in the economizer gas passage 20 is controlled in reference to a detected value of the gas temperature sensor 22 so as to control a flow rate of the refrigerant.
|
