A single-unit two-stage variable-frequency screw compressor with adjustable internal volume ratio

Abstract

The invention relates to a screw rod refrigeration compressor. Provided is a stand-alone two-stage variable frequency screw rod compressor with an adjustable internal volume ratio, i.e., a low-pressure stage screw rod compression part and a high-pressure stage screw rod compression part are respectively provided with an internal volume ratio regulating valve having an adjustable position. The internal volume ratio regulating valve is embedded at a joint of two excircles of a female rotor and a male rotor inside a housing along an axial direction of a rotor; and the internal volume ratio regulating valve is located on the side of a compressed air. One side of the internal volume ratio regulating valve close to an exhaust end seat is provided with a rotor radial exhaust port. The internal volume ratio regulating valve is connected with a drive device; and the internal volume ratio regulating valve can move within a designated permitted range forward and backward along the axial direction of the rotor under the actuation of the drive device; additionally, the load or the capacity of the compressor is regulated by employing a frequency converter to supply power to a drive motor. The working efficiency of the stand-along two-stage screw rod compressor under variable working conditions and variable loads is increased by respectively arranging the internal volume ratio regulating valve at the high-pressure stage screw rod compression part and the low-pressure stage screw rod compression part in combination with a variable rotation speed load regulating method.

Description

technical field [0001] The invention relates to a screw type refrigeration compressor, in particular to a single-machine two-stage frequency conversion screw type refrigeration compressor with adjustable internal volume ratio. Background technique [0002] As we all know, the screw compressor is through the rotation of the male and female rotors that are placed in the casing and meshed with each other in parallel, resulting in the reduction of the compression working volume composed of the rotor suction end seat, the tooth groove, the shell and the exhaust end seat. Compression of inhaled gas. In a complete compression process, the gas has to go through three stages of suction, compression and exhaust along the direction of the rotor axis. [0003] For the adjustment of capacity, the screw compressor generally adopts a slide valve mechanism, and the effective suction working volume is reduced through the movement of the slide valve, thereby realizing the adjustment of the g...

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Problems solved by technology

[0012] Aiming at the problems existing in the prior art, the purpose of the present invention is to overcome the problem that the existing single-unit two-stage screw compressor allows the condensing temperature and the evaporation temperature to vary within a relatively large range, and the corresponding working pressure ratio is also within a relatively large range. In a refrigeration system with fluctuations (for example, the external pressure ratio of the air source heat pump of the ultra-low temperature R134a (1,1,1,2-tetrafluoroethane) refrigerant is about 4.0<εo<15), due to the working pressure ratio of the high-pressure stage or low-pressure stage and the corresponding The low efficiency of the compressor caused by the excessive deviation of the internal pressure ratio caused by the additional overcompression or undercompression loss, and the low efficiency and poor economy of the compressor when the system is running at low load

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