This article describes a newly developed vacuum performance of the proliferation of automatic test systems. The system can be provided in accordance with national standard method of automatic detection limit of diffusion vacuum pump pressure and pumping speed. System uses self-developed light Power level detection methods and components to achieve the automatic liquid dropper when read and write; achieved using stepper motor needle shield gas flow and pressure test the automatic adjustment; use of upper and lower PC, dual-level control of the microcontroller System implementation system of the entire test system and test process automation. As the most widely used high-vacuum pumping equipment, oil diffusion pumps in domestic production, research has reached a considerable level of technology and a certain scale of production, is widely used in machinery, electronics, metallurgy, atomic energy, Space simulation, and industrial areas and scientific and technological research, the development of our country made a significant contribution. In recent years, the domestic diffusion pump products from the appearance and function to the performance of all the great progress. Diffusion pump with respect to the number and total production of manufacturing enterprises, the domestic diffusion pump in terms of product performance testing is relatively backward. At present, many enterprises still do not own performance testing system, the pump products in the factory The lack of actual performance testing. Related to existing domestic detection system are used full manual operation mode, the operator had a higher knowledge and experimental skills required, subject to special training can perform the job And test data accuracy is affected by many human factors, which are for the manufacturers to carry out their own independent diffusion pump performance test more difficult. For this situation, the paper developed a diffusion vacuum pump performance of the automatic test system. The following principles will be a test of the system, hardware and software structure, development process of the technical difficulties encountered and solutions Measures for the introduction. 1, the automatic test system testing principle The test system set the limit on the diffusion pump inlet pressure and the pressure under different pumping speed curve of the testing principle and method, strictly in accordance with the provisions of the relevant national standards. Diffusion pump which automatically detect speed curve, A "constant pressure method," Principles of testing. Measurement points for each one corresponding to the test steps are: the working valve open conditions, using the needle valve adjustment cover charge into the test gas flow Q, the equilibrium pressure inside the test hood and stability in the pre-p Vicinity of the pressure value; close the valve, the liquid column in order to reach record level dropper height h1 and h2 of the time t1 and t2; lifting height by calculating the net liquid column h = h2-h1 and rise time t = (t2 -t1), using the following formula requirements Was the corresponding volume flow rate under pressure, that is pumping speed. S = Q / P = Kh / Pt Where S --- measured vacuum pumping speed, L / s Q --- the mouth of the gas flow through the pump flow, Pa · L / s p --- test cover the balance of pressure within the specified location, Pa h --- dropper net increase in fluid column height, mm t --- dropper rise time within the liquid column, s K --- dropper function, Pa · L / mm. Based on the above formula indicates: To calculate the pumping speed S, the corresponding measurement points need to known the K, h, p and t. Where the function K can dropper dropper and connecting pipes of different sizes, combined with what the actual test conditions Be calculated; Therefore, the actual need to read the test covers only the specified location equilibrium pressure p, the net lift dropper liquid column within the liquid column h and the time required for the net lift height h t three quantities. The test system has a set of automatic test Function, mainly refers to the work of valves open and close automatically using solenoid valve; needle used to complete the process of flow control stepper motor driver, and the pressure under the hood measured compared with the preset pressure feedback control; use of photoelectric Determination of liquid level switches in the set position dropper h1 and h2 the height of the time t1 and t2. The entire testing process, and after the pumping speed calculation, output work done by computer control, but in a more Dropper and the connecting pipe for the process of manual work required in the operator. 2, the automatic test system hardware structure 2.1, machine parts The main mechanical parts of the test system design based on the detailed provisions of national standards. Mainly by the test covers, lifting mechanism, the front valve, pre-pumping valve, working valve, release valve, valve trim, dropper, optical level open Customs, storage sump, trolleys and vacuum hose and other components, measured as the K-200 main pump-type oil diffusion pump, the front for the 2X-4 type rotary vane pump. Taking into account the main purpose of the test bed is to serve the Northeastern University, Process Equipment and Control Engineering undergraduate vacuum experimental teaching, so in the structure and function is subject to change, extension. Corresponds to K-200 type oil diffusion pump The diameter of 200mm should be used in the test cover, but considering the use of other teaching experiment, the system uses 400mm diameter test cover, install tapered transition between interface and flapper valve and the measured diffusion pump connected. These will be Led to the increase in pipe flow conductance, so that the pump pumping speed measured values decrease, but does not affect the testing system works and use. The test cast also left two vacuum gauge interface, a former stage valve interface, a micro- Adjusting the inlet valve, the top left gas discharge port, and links to other vacuum test equipment two spare interfaces. Enhance the body can bring the test cover to facilitate the replacement of the main pump and other teaching was accomplished. To take into account the real Are automatic control, all the valves are solenoid-driven choice. In addition, according to the experimental needs, but also ordered a special 1.5,3,5,10,20,30,50 mm diameter were a series of pipettes. Based on the above formula indicates: To calculate the pumping speed S, the corresponding measurement points need to known the K, h, p and t. Where the function K can dropper dropper and connecting pipes of different sizes, combined with what the actual test conditions Be calculated; Therefore, the actual need to read the test covers only the specified location equilibrium pressure p, the net lift dropper liquid column within the liquid column h and the time required for the net lift height h t three quantities. The test system has a set of automatic test Function, mainly refers to the work of valves open and close automatically using solenoid valve; needle used to complete the process of flow control stepper motor driver, and the pressure under the hood measured compared with the preset pressure feedback control; use of photoelectric Determination of liquid level switches in the set position dropper h1 and h2 the height of the time t1 and t2. The entire testing process, and after the pumping speed calculation, output work done by computer control, but in a more Dropper and the connecting pipe for the process of manual work required in the operator. 2, the automatic test system hardware structure 2.1, machine parts The main mechanical parts of the test system design based on the detailed provisions of national standards. Mainly by the test covers, lifting mechanism, the front valve, pre-pumping valve, working valve, release valve, valve trim, dropper, optical level open Customs, storage sump, trolleys and vacuum hose and other components, measured as the K-200 main pump-type oil diffusion pump, the front for the 2X-4 type rotary vane pump. Taking into account the main purpose of the test bed is to serve the Northeastern University, Process Equipment and Control Engineering undergraduate vacuum experimental teaching, so in the structure and function is subject to change, extension. Corresponds to K-200 type oil diffusion pump The diameter of 200mm should be used in the test cover, but considering the use of other teaching experiment, the system uses 400mm diameter test cover, install tapered transition between interface and flapper valve and the measured diffusion pump connected. These will be Led to the increase in pipe flow conductance, so that the pump pumping speed measured values decrease, but does not affect the testing system works and use. The test cast also left two vacuum gauge interface, a former stage valve interface, a micro- Adjusting the inlet valve, the top left gas discharge port, and links to other vacuum test equipment two spare interfaces. Enhance the body can bring the test cover to facilitate the replacement of the main pump and other teaching was accomplished. To take into account the real Are automatic control, all the valves are solenoid-driven choice. In addition, according to the experimental needs, but also ordered a special 1.5,3,5,10,20,30,50 mm diameter were a series of pipettes.

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