Unloading control method of screw compressor

Abstract

The invention belongs to the technical field of compressors, and aims to solve the problem that normal operation of a screw compressor in the prior art is affected due to the fact that the screw compressor in the prior art often has the problems of shutdown, alarm and the like. Therefore, the invention provides an unloading control method of a screw compressor, and the unloading control method comprises the following steps: when the screw compressor starts to unload from a full load state, controlling a second oil drain valve and a third oil drain valve to enable a second oil drain pipe and a third oil drain pipe to drain oil at the same time and maintain for a set time, therefore, a piston moves from the full-load position to the position of a second oil drain port; and when the piston moves to the position of the second oil drain port, the second oil drain valve is controlled to stop oil drain of the second oil drain pipe, the third oil drain valve is controlled to keep oil drain of the third oil drain pipe, and therefore the piston is kept at the position of the second oil drain port. According to the method, the unloading speed of the screw compressor can be increased, the unloading time can be shortened, and the problems that the screw compressor is shut down or alarms due to the fact that the unloading time is too long are solved.

Description

technical field [0001] The invention belongs to the technical field of compressors, and specifically provides an unloading control method of a screw compressor. Background technique [0002] Compressor is a kind of fluid mechanical equipment that can upgrade low-pressure gas to high-pressure gas. According to the category, it can be divided into reciprocating compressors, screw compressors, rotary compressors, scroll compressors and centrifugal compressors. Screw compressors are typically used in large commercial and industrial systems. [0003] Take the screw compressor of a commercial air conditioner as an example. A commercial air conditioner is a device that can adjust the temperature of the indoor environment. The working cycle of the screw compressor can be divided into three processes: suction, compression, and exhaust. However, in the process of actual application, the screw compressors of commercial air conditioners often have problems such as shutdown and alarm, a...

AI Technical Summary

Problems solved by technology

[0005] In order to solve the above-mentioned problems in the prior art, that is, in order to solve the problem that the existing screw compressor often has problems such as shutdown and alarm that affect its normal operation, the present invention provides a method for unloading control of the screw compressor. The compressor includes a piston cavity, a piston, a piston rod, a capacity adjustment slider, an oil supply pipe, a first oil drain pipe, a second oil drain pipe, a third oil drain pipe and an oil tank, and the first oil drain pipe is provided with a first oil drain valve, The second oil drain pipe is provided with a second oil drain valve, and the third oil drain pipe is provided with a third oil drain valve. The two ends of the piston rod are respectively connected with the piston and the capacity adjustment slider. The change of oil quantity moves relative to the piston chamber to move the capacity adjustment slider. The capacity adjustment slider can cooperate with the rotor of the screw compressor to adjust the load of the screw compressor. The inlet of the oil supply pipe is connected with the oil tank, and the outlet of the oil supply pipe It communicates with the piston chamber, the inlet of the first oil drain pipe communicates with the oil supply pipe, the inlet of the second oil drain pipe communicates with the first oil drain port of the piston chamber, and the inlet of the third oil drain pipe communicates with the second oil drain port of the piston chamber , the outlet of the first oil drain pipe, the outlet of the second oil drain pipe and the outlet of the third oil drain pipe are all in communication with the oil groove, the first oil drain port and the second oil drain port are arranged in sequence along the moving direction of the piston relative to the piston cavity, the The unloading control method includes: when the screw compressor starts unloading from a full-load state, controlling the second oil drain valve and the third oil drain valve so that the second oil drain pipe and the third oil drain pipe drain oil at the same time and maintain the set time, so that The piston moves from the full load position to the position of the second oil drain port; when the piston moves to the position of the second oil drain port, the second oil drain valve is controlled so that the second oil drain pipe stops draining oil and the third oil drain valve is controlled to keep The third drain line drains the oil so that the piston remains in the position of the second drain port

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