A control method and control device for nitrogen-filling, pressure-maintaining and vacuum-pumping equipment

Abstract

The invention discloses a control method and control device of nitrogen filling and pressure maintaining vacuumizing device and relates to quality detection and control on compressors, devices or systems using low boiling point gas as a refrigerant. The control method comprises the following steps: connecting a machine unit to a nitrogen filling pipeline; automatically filling a to-be-detected machine unit with the nitrogen through a constant-pressure gas tank; switching off a nitrogen filling valve by a first pressure detection element after the nitrogen filling is finished; connecting the machine unit to a vacuumizing pipeline; connecting a pumping electromagnetic valve; starting a vacuum pump to pump the gas to a high pressure gas tank; switching off the pumping electromagnetic valve through a second pressure detection element after the pumping is finished; and switching on a gas supplement electromagnetic valve through a third pressure detection element to supplement the gas to the high pressure gas tank. The constant-pressure valve is used for supplementing the gas to the constant-pressure gas tank; the centralized gas supplementing is realized through the constant-pressure gas tank; the pressure stability of the constant-pressure gas tank is guaranteed; the gas filling speed is high; pressure detection elements are used for detecting and controlling gas filling pressure; the pressure offset of pressure maintaining is small; an existing pressure maintaining and leakage detection mode can be replaced and the requirement of small batches and multiple varieties on a modern flexible production line can be met.

Description

technical field [0001] The present invention relates to a quality detection and control device for compressors, devices or systems in which low-boiling point gas is used as refrigerant, and in particular to a control method and control device for nitrogen-filled, pressure-maintained and vacuum-extracting equipment used in heat pump-refrigerating units . Background technique [0002] In the production process of heat pumps and refrigeration systems, leak detection must be carried out to ensure their quality. Due to the low temperature of liquid nitrogen, easy preparation, low cost, and no pollution, many companies use it in the production process of heat pumps and refrigeration systems. In China, the heat pump-refrigeration unit is leak-tested by nitrogen filling and pressure-holding leak detection method. After the leak detection is completed, the nitrogen gas is directly discharged into the surrounding air without recycling. Dozens of machines are produced every day, result...

AI Technical Summary

Problems solved by technology

However, in the actual production process, the product models and batches on the production line are constantly changing, especially for modern flexible production lines with small batches and multiple varieties, the systems to be leaked at the same time and the systems that have been leaked often belong to different models or Different batches of products, therefore, the amount of nitrogen discharged from the leak detection system is not equal to the nitrogen filling amount of the leak detection system in most cases. The above-mentioned nitrogen gas discharged from the leak detection system is directly transferred to the leak detection system It is difficult to realize the effective nitrogen recovery and utilization function of the existing technical solutions

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