Design And Research On Hydraulic System Of Casing Turnover Washing Machine

The casing turnover washing machine is a kind of equipment for washing the accessory casing of aero-engine.The pressure,flow rate and temperature of the washing fluid from the washing machine determine the cleanliness of the casing after washing.From a macroscopic view,each casing can be regarded as a hydraulic orifice with fixed damping state.In other words,there is a functional relationship between the flow rate through the casing and the pressure difference between the front and rear flow ports of the casing.Controlling the pressure is equivalent to controlling the flow rate.Therefore,the key to ensuring the efficient washing effect is to achieve the accurate control of the pressure and relatively high temperature at casing inlet.It is of great practical value to design the hydraulic system of the washing machine comprehensively and accurately,and to study how to achieve the accurate control of pressure and temperature.The hydraulic system of the washing machine is fully studied and designed with technical requirements introduction.The complete schematic diagram of the hydraulic control system and the lectotype design for the main hydraulic components are given.The mathematical model is established for the closed-loop pressure control system at casing inlet based on classical control theory,and the system stability analysis is conducted by applying the Bode criterion.In order to further ensure the accuracy of the research on the dynamic characteristics and control accuracy of the closed-loop pressure control system,a comprehensive and accurate dynamic model of the system is established by using AMESim software.The PID correction is preliminarily used to control the system,and the dynamic characteristics and errors of the system before and after correction are analyzed.In order to further improve the control performance of the system,the piecewise PID control method is used to control the system,and the corresponding analysis process and results are given.The temperature control system of this equipment can be divided into two systems,one is the pre-heating and heat preservation system of the oil in the oil tank,the other is the casing inlet washing temperature control system.AMESim software is used to model the above temperature systems,and contrastive analysis is conducted towards multiple temperature control schemes.The result about how installation position of temperature sensor impacts temperature control performance of the system is given.In order to further reduce system energy consumption,the proportional relief valve is used to replace the regular type based on the energy consumption analysis,which has received good result.The results show that the response speed,dynamic error and steady-state error of the pressure control system of the washing machine can meet the requirements after PID correction.By using piecewise PID control method,the pressure control accuracy can be further improved.The steady-state error values of 4 bar,6 bar and 8 bar can be reduced by4.1%,20% and 58.7% respectively.For the pre-heating and heat preservation system of the oil in the oil tank,the accuracy requirement can be met by using mere heater to control the temperature.For the casing inlet washing temperature control system,using cooler in conjunction with heater is needed to meet the requirement.The energy consumption of the closed-loop pressure control system is improved notably by using the proportional relief valve.The energy saving effect is the best when the system working pressure is 1.5 bar,and the energy consumption can be reduced by 32.5%.