Double-stage air replenishing compressor, freezing and cold storage refrigerating system and control method

Abstract

The invention provides a double-stage air replenishing compressor, a freezing and cold storage refrigerating system and a control method. The double-stage air replenishing compressor comprises a low-pressure-stage compression cavity, a high-pressure-stage compression cavity and a middle air replenishing cavity. The low-pressure-stage compression cavity is provided with a low-pressure-stage suctionport and a low-pressure-stage exhaust port. The high-pressure-stage compression cavity is provided with a high-pressure-stage suction port and a high-pressure-stage exhaust port. The middle air replenishing cavity is provided with an air replenishing port and a mixing exhaust port. The low-pressure-stage compression cavity is connected with the middle air replenishing cavity through the low-pressure-stage exhaust port in a communicating manner. According to the double-stage air replenishing compressor, the freezing and cold storage refrigerating system and the control method, when the external environment temperature is low, the system is switched into the state that a high-pressure-stage air cylinder and a low-pressure-stage air cylinder run in parallel, thus, the operating frequency ofthe compressor can be reduced while the requirements of the refrigerating capacity are met, then the phenomenon that a slip sheet and a roller in the high-pressure-stage air cylinder disengage to generate collision noise is effectively eradicated completely, and the performance reliability of the compressor is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of refrigeration, and in particular relates to a two-stage air supply compressor, a refrigeration system for freezing and refrigeration, and a control method. Background technique [0002] Compared with ordinary single-stage rolling rotor compressors, under the condition of large pressure ratio and large pressure difference, the two-stage compression intermediate air supply rolling rotor compressor has greater cooling / heating capacity and better performance coefficient. At the same time, the setting of the air supply pipeline can effectively reduce the discharge temperature of the compressor, which greatly improves the reliability of the compressor under severe working conditions such as large pressure ratio and large pressure difference. Type compressors have been more and more widely used in the field of refrigeration. [0003] However, when the current two-stage air-supplementing rotary compressor is app...

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Problems solved by technology

[0003] However, when the current two-stage air-supplementing rotary compressor is applied to the field of refrigeration and refrigeration, it encounters a technical problem, that is, refrigeration is still required when the outdoor ambient temperature is low (such as winter), and usually the refrigerator is in a warm room (such as supermarkets, residential buildings, etc.) ), the load is heavy at this time, and the unit usually needs to operate at high frequency. The high-speed two-stage supplementary air rotary compressor has a small suction and exhaust pressure difference. The volume ratio is generally small. Under high-pressure ratio freezing and refrigeration conditions, a small volume ratio can obtain a more reasonable two-stage compression ratio distribution, that is, the interstage pressure (both the exhaust pressure of the low-pressure stage compression chamber and the high-pressure stage The suction pressure of the compression chamber) is in the middle, but the two-stage supplementary air compressor with a small volume ratio is under low-temperature refrigeration conditions with a small compression ratio, and the discharge pressure of the low-pressure stage compression is almost equal to the discharge pressure of the compressor. In this way, the suction and exhaust pressures of the high-pressure cylinder are basically equal, that is, the gas pressure difference on the slide of the high-pressure cylinder is small, so that the slide of the high-pressure cylinder of the compressor is easy to separate from the roller in a certain angle range, especially in the When the sliding plate and the roller surface are at 0°, the separation force (roller and sliding plate running at high speed, the sliding plate has a huge centrifugal force) reaches the maximum, and the sliding plate has penetrated into the sliding plate groove and collides with the cylinder, causing performance attenuation and noise anomalies

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