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Key words: CVT Clamping Force Control Fund Project “The Ninth Five-Year Plan must take measures to prevent the integrator from terminating, that is, the clamping force control valve must always work within the controllable range. This obviously cannot be solved by conventional control methods. In the design of the control system, a feedforward anti-rewind PID controller is used to prevent the integrator from rewinding. The system provides an additional feedforward channel. The controller measures the output of the actuator model to form an error signal. The difference between the actuator output and the controller output, and this error is fed back to the integrator through the gain 1/%. When the actuator is not saturated, the error signal 匕 is zero. When the actuator is saturated, the additional feedback channel tries. Make the error signal equal to zero. This means that the integrator reset causes the controller output to be at the saturation limit. The integrator then traces the time constant % (called the tracking time constant to an appropriate value. The actuator model is pre-tested Mathematical model, its output can be approximated as the value of the actual actuator output. In order to reduce the system's overshoot Into a feedforward channel. The addition of the feedforward channel can make the initial output of the controller large and reduce the influence of the integral link, so that the response of the system is accelerated. Only when the error controls the output of the controller to the linearity of the saturated nonlinear component The integrator only works in the interval. The description of the controller output is as follows: The engine speed 1 is based on the above theory. The clamping force control system block diagram is shown. The duty cycle of the effective PWM signal due to the clamping force control valve is There are differences at different speeds, so the effective duty ratio corresponding to different speeds can be made into a table, so that the duty cycle of the saturation limit can be determined by interpolation at different speeds. The actual input of the rewinding PID controller has a system-set target value, an output feedback value of the clamping force control valve, and an input speed of the current system. The controller first determines the saturation interval of the clamping force control valve at the rotational speed according to the input rotational speed. The limit value is then controlled based on the deviation of the target value from the system feedback.
I start ~2丨->Clamping force control valve-~ PID controller clamping force control system consists of 4 clamping force control system model simulation and experimental research in order to verify the correctness and reliability of the clamping force control model discussed The simulation test results of the clamping force control model designed according to the block diagram of the above clamping force control system are shown. When the target clamping force changes stepwise, the curve of the output pressure value from the controller can be seen, the clamping force overshoot is small and stable, that is, the controller can play a better control role.
Simulation curve of clamping force controller In order to further study the actual control effect of the designed control system, the CVT control system composed of the CVT clamping force control system and the proposed speed ratio control system was transplanted to the vehicle for the whole vehicle. Test, the test results are as shown.
Visible, in! At 1 o'clock, the engine acceleration engine speed increases with the input of a certain throttle opening. The control system determines the target speed ratio according to the current input, outputs a signal to the clamping force control valve and the speed ratio control valve, controls the pressure changes of the main and driven wheel cylinders, and increases the actual speed ratio to the target speed ratio to change the vehicle speed, each parameter The changes are shown in the figure. At t! At the moment, when the throttle opening of the engine is further increased (/), the target speed ratio corresponding to the change of the engine speed of the throttle opening changes, the control system controls the pressure of the main and driven wheel cylinders to further change (d) The actual speed ratio is approached to the target speed ratio. (c) The engine speed and the speed of the vehicle are as shown in b. That is, when the system reaches the steady state, the actual speed ratio is equal to the target speed ratio, and the vehicle speed of the vehicle no longer increases. At the time t3, when the driving resistance suddenly increases, the control system passes the control of the main and driven pulley cylinders because the throttle opening of the engine remains unchanged and the target speed of the engine does not change corresponding to the target speed ratio of the current driving condition. The pressure controls the actual speed ratio to change toward the low gear.
The test results show that the control system can control the appropriate clamping force to adjust the speed ratio according to the requirements of driving conditions to meet the actual needs.
5 Conclusion u. Through the experiment to study the working characteristics of the clamping force control valve; modeling and optimization of the nonlinear rubber suspension dynamics of engineering vehicles!
Sun Wei Xu Zhihua Sun Qinghong (Southeast University) method optimizes the suspension characteristics of different loads, different grades of pavement and different vehicle speeds to the optimal suspension characteristics under different working conditions. The ideal nonlinear characteristic curve of rubber suspension stiffness parameters is obtained by least squares fitting. The simulation results show that the optimized rubber suspension system can maintain good ride comfort.
Key words rubber suspension multi-flexible dynamics nonlinear optimization engineering vehicles operating on non-road surfaces with poor working conditions, the suspension system tends to undergo large deformation, and there is strong nonlinearity, time-varying and dynamic. How to make such vehicles have good adaptability and reliable work for complex use conditions, has been caused by the International Natural Science Foundation of China (50575040) funded by the Natural Science Foundation of Jiangsu Province (BK2003202) 8 Zhang Boying. Research on mechanism and control of metal belt type continuously variable transmission. Changchun Jilin University 2003. (Responsible editor Wen Hao) 31 Fu Tiejun and other metal belt type continuously variable transmission electro-hydraulic control system experimental research 丨lishingHouse.Allrights to prevent integrator rewind, designed a PID controller with feedforward anti-windback It is applied to the designed clamping force control system to simulate the designed clamping force control model, and the loading control test is carried out on the integrated control system equipped with the clamping force controller.
The results show that the designed controller is reliable and has practical value.