Research For The Adjusting Device And It’s Control Of The Front Clearance Of The Centrifugal PUMP’s Impeller

Centrifugal pump is a typical fluid machinery, it transports liquid through the centrifugal effect produced by the rotation of the impeller. While the impeller features in the centrifugal pump’s structure, the clearance between the impeller and the front pump lid is the essential factor measuring the volume efficiency of the centrifugal pump. After a period of operation of the centrifugal pump, the front clearance of the impeller is subject to changes owing to factors like wear and tear, distortion, etc. Pump with big clearance and much leakage leads to its low efficiency, while small clearance results in its break-down because of the friction between impeller and lid. So during the period of using pump, the real-time monitoring as well as the adjustment and control are practically deserving of research in keeping the high efficiency of the pump. The shut-down of the system,the loading and unloading of the impeller and lid inevitably cause the impreciseness, the complexity and the low efficiency of the present adjustment. Thus,in order to make up this deficiency,the thesis aims at designing the electro-hydraulic servo position control system for the clearance of the centrifugal pump’s impeller and at researching its control performance by adopting the double calculation of fuzzy PID and fuzzy immune PID in order to keep the clearance within the appropriate range.First, the adjusting device for the front clearance of the centrifugal pump’s impeller is designed. Then, through reforming some structure parts of the centrifugal pump’s front cover, the front pump’s cover which have translation function and deformed structure of hydraulic cylinder is designed. Since the impeller’s position remains unchanged,the front clearance of impeller is changed. Various types of hydraulic components are calculated and selected, and required parameters of the mathematical model of electro-hydraulic servo position control system are identified, the hydraulic system simulation is carried out by AMESim. Then the mathematical model of the hydraulic control system for the front clearance of the impeller is established, the state space expression is derived,and the stability,observability and controllability of the system are analysed. According to fuzzy PED algorithm and immune algorithm, The fuzzy PID controller and the fuzzy immune PID controller are designed. The simulation model of the electro-hydraulic servo position control system for the adjusting device for the front clearance of the centrifugal pump’s impeller is established to make comparative research of simulation based on Simulink.The main achievements of this paper are as follows:1, the adjusting device with unique structure for the front clearance of the centrifugal pump’s impeller is designed; 2, the mathematical relationship between the affordable pressure difference of the lid and the front clearance of the impeller is described under the condition of zero leakage; 3, fuzzy PID and fuzzy immune controller for the front clearance of the centrifugal pump’s impeller are designed; 4, the last simulation results show that the response speed, adjust time and overshoot of fuzzy PID control, fuzzy immune PID is shorter than conventional PID control,between the first two controls, the effect of control of fuzzy immune PID is better than fuzzy PID control.