Multi-split system

Abstract

The invention discloses a multi-split air conditioning system which comprises an outdoor unit provided with an outdoor heat exchanger, an outdoor throttling device connected with the outdoor heat exchanger and a compressor. The plurality of indoor units are provided with indoor heat exchangers and indoor throttling devices, and the plurality of indoor heat exchangers are respectively connected with the outdoor heat exchanger through refrigerant piping; the controller is configured to adjust the opening degree of the outdoor throttling device and the opening degree of the indoor throttling device according to the operation mode of the system, when the operation mode is the refrigeration operation mode, the outdoor throttling device is controlled to be fully opened, the opening degree of the indoor throttling device is not smaller than the lower limit value of the indoor throttling opening degree, and when the operation mode is the heating operation mode, the outdoor throttling device is controlled to be fully closed. And the indoor throttling device is controlled to be fully opened, and the opening degree of the outdoor throttling device is not smaller than the outdoor throttling opening degree lower limit value. According to the multi-split system, the minimum throttling opening degree of the indoor unit and the outdoor unit is determined by setting the minimum valve opening degree control, the circulating refrigerant amount of the system is ensured, vacuumizing of the system is prevented, and the comfort of a user and the reliability of the compressor are improved.

Description

technical field [0001] The invention relates to the technical field of air conditioners, in particular to a multi-connection system. Background technique [0002] In the multi-connection system, one outdoor unit is connected to two or more indoor units through pipes. The outdoor side mostly adopts air-cooled heat exchange, and the indoor side mostly adopts direct evaporative heat exchange. [0003] As the cost requirements become more and more stringent, in order to develop products that can meet product reliability and low cost, many air-conditioning products cancel the low-pressure pressure sensor, and calculate the low pressure of the system through the temperature and other values. In the transition stage, the low pressure estimation is not accurate, and some will be inaccurate for a long time. If the compressor frequency, fan control and throttling device control are not controlled in time, the compressor will be in a vacuum state, not only the user's comfort is not goo...

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Problems solved by technology

[0003] As cost requirements become more and more stringent, in order to develop products that can meet product reliability and low cost, many air-conditioning products have canceled the low-pressure pressure sensor, and calculate the low pressure of the system through temperature and other values. In the transition stage, the low pressure calculation is inaccurate, and some calculations are inaccurate for a long time. If the compressor frequency, fan control and throttling device control are not timely, the compressor will be in a vacuum state. Not only the user comfort is not good, but the compressor also easily damaged

[0004] Due to the characteristics of multi-connection products, such as large differences in the length of connecting pipes, large differences in the ratio of indoor and outdoor units, and different operating loads for some indoor units and all indoor units, low pressure may occur under individual working conditions or individual online schemes according to the above calculation method. In the case of inaccurate pressure calculation, especially at the start-up stage of the unit, the whole system is not yet in stable operation, and the system is prone to vacuuming. Since the low pressure is inferred by temperature, the system temperature response lags behind. At this time, it is calculated based on temperature. The low-pressure pressure is not low (the actual low-pressure pressure is low), and the compressor frequency, fan speed, throttling device control, etc. will not change the control in the direction of increasing the low-pressure pressure, resulting in low-pressure pressure will continue to be low or continuous vacuuming, thus As a result, user comfort cannot be guaranteed, and the compressor is easily damaged

[0005] It is difficult to verify the vacuuming of the system in a large amount of test data. It is necessary to draw this conclusion based on a large number of actual application conditions, compressor failure conditions, and compressor failure analysis data. Whether the specific compressor damage is caused by the system If it is caused by vacuuming, it needs specific dissection and detailed analysis to draw a conclusion, which also increases a lot of difficulty and workload for later maintenance and cause finding

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