Research And Realization Of Vehicle Oil Cooler's Fatigue Property Pulsation System Based On Fuzzy-PID Control

Oil cooler is a key component in the lubrication system of I.C. engine, and its quality plays a great role in the engine's performances. Fatigue property test is one of the quality tests for oil coolers. In order to meet the increasing demand on controlling accuracy during tests, a new control system for fatigue property pulsation test-bed is developed by combining electro hydraulic proportional technology and fuzzy PID control, which improves controlling effects, as well as the stability of the whole system.Main contents of this paper are as following:(1) The basic principles of oil cooler and fatigue property pulsation test were introduced, the developments and features of electro hydraulic proportional technology in general was discussed, and the presently different kinds of controlling strategy in electro hydraulic technology was summarized.(2) A group of fundamental principles including PID, fuzzy and fuzzy-PID were introduced comprehensively. The design process of fuzzy controller was presented in detail, and with facts the solving strategies to the vital problems bubbling up during the process were analyzed.(3) Mathematic model of the system was built up, according to the features of fatigue property pulsation bench. The design process of fuzzy-PID controller for the system was accomplished. Bring up the mathematic process of fuzzy deduction, and data during the calculation was proposed, which provides comparison with other fuzzy deductive rules.(4) The structure of the whole system was developed, according to the concept of DCS, and the selection for controlling hardware devices and design for the inner controlling circuits was completed, moreover, their controlling theories and functions of each part was analyzed.(5) In order to meet the controlling requirements, software flow process for upper and lower computer were designed, and programs based on the controlling parameter adjustments by fuzzy PID for them was accomplished. A communication agreement between up and down machines was made up, as well as down machine and temperature controllers.(6) Fuzzy PID controller was designed and simulation model of the system was built up by fuzzy logic toolbox in Matlab/Simulink, and the simulation of step response was performed, sensor interference and sine wave response under two separate controllers: PID and fuzzy PID, and effects of the two controllers were analyzed during the process. Based on the analysis, the control performance of Fuzzy-PID Controller is better than PID Controller's in the aspect of reducing overshoot, shorten the dynamic regulating time. The system got a better following performance and stability, and in the situation of changing some performance parameters of the system, Fuzzy-PID Controller can still remain a better control effect.