| In this paper,the hydro-viscous speed control system of the tank and armored vehicle cooling fan is studied.The working principle of the hydro-viscous clutch and the transfer characteristics of oil film were analyzed which is the core components of the hydro-viscous speed control system.For the traditional control accuracy of single closed loop with speed negative feedback control system is low,the control strategy does not consider the influence of input speed on output speed of hydro-viscous clutch and the reasonable work area of the hydro-viscous clutch plates,the transfer function of the system is obtained by using the method of system identification.Based on the transfer function,the adjustment rule of self-tuning PID is established by using the double layer optimization algorithm.A cascade control strategy which includes outer loop control of engine temperature and inner control of fan speed is also developed.The feasibility and control effect of the control strategy are verified by the test bench and the vehicle test.The present situation of the cooling fan speed control technology in the tank and armored vehicle is carried out and the problems of the hydro-viscous clutch control strategy are analyzed.Then the main content of the research in this paper is proposed.Based on the research achievements of the hydro-viscous clutch at home and abroad,this paper establishes the modified transient Reynolds equation considering the influence of the oil film extrusion effect and oil film centrifugal force.On the basis of the equation,the film transfer characteristics of the oil film with and without groove friction pair are analysed.Taking a type of the hydro-viscous clutch and electric hydraulic proportional valve control system as an example,the mathematical model of hydro-viscous speed control system is established and the theory transfer function of system is obtained.Through the simulation,the basic characteristics of hydro-viscous speed control system is analyzed.Based on the open loop characteristics testing,the transfer function of the hydro-viscous clutch is obtained using method of least squares and the simulation model is improved by the transfer function of identification.Finally,through the experiment the credibility of the simulation model is verified.Aiming at the disadvantages of the hydro-viscous speed control system of tank and armored vehicle which can not realize the stepless speed regulation and the large disturbance of the system temperature and the speed of the fan,this paper proposes the multiple parameters feedback control strategy which contains engine temperature,engine speed,fan speed and oil pressure of the hydro-viscous clutch.The control strategy mainly includes:(1)achieving the target speed following the change of temperature and speed of the engine by using the engine water temperature and engine speed to set target fan speed;(2)achieving actual fan speed following the target speed fan by the negative feedback control of the fan speed and control oil pressure of the hydro-viscous clutch;(3)for the hydro-viscous speed control system has the characteristics of variable and nonlinear,developing the system of self-tuning PID controller parameter adjustment rules based on a bi-level optimization algorithm,simulating the good robustness of the method and achieving the stable output of the fan speed and temperature of the system.In this paper,the bench and vehicle test is performed to verify the system of self-tuning PID controller parameter adjustment rules based on a bi-level optimization algorithm and the cooling fan control strategy.It realizes the the stepless speed regulation of hydro-viscous clutch within the ratio of 0.3~0.7 and the accuracy control of the temperature and fan speed changes.Test results and simulation results also maintain a good consistency. |
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