Development And Experimental Verification Of Engine Electronic Thermostat

With the development of automobile industry and the increase of car ownership, energy consumption and environment pollution of automobile has been paid more and more attention, in recent years. Laws against energy consumption and pollution have become more and more stringent throughout the world. In order to save more energy and discharge less emission, cooling system of engine needs to be redesigned. Intelligent and electronic control is the development direction of engine cooling system. Thermostat is a key component in engine cooling system, which is used to control the flow path of water coolant. However, wax is used in almost all thermostats as temperature-sensing element, which has response delay and hysterics characteristic, can not meet the requirement of engine cooling system precise control. In this paper, an electronic thermostat was designed. Electric three-way proportion valve was used as actuator. And the control strategy was based on fuzzy control principle. During the design process, the 1-D numerical simulation model of engine cooling system was built with the aid of GT-COOL, while the controller model of electronic thermostat was built with the aid of MATLAB/SIMULINK. And then, the co-simulation of the two models was run, so as to get the optimal control strategy of electronic thermostat. Additionally, experiment research was carried out to test and verify the practicability of electronic thermostat fuzzy control strategy.The following works are completed in this thesis:1. Established the GT-COOL numerical simulation model of engine cooling system, based on computational fluid dynamics. And verified correctness of the model by experiment.2. Designed the electronic thermostat, taking electric three-way proportion valve as actuator, and fuzzy control principle as control strategy.3. Run the co-simulation of GT-COOL model and SIMULINK model, so as to get the optimal control strategy of electronic thermostat.4. Built the simulation test bench of engine cooling system, run the control strategy in an embedded control unit; realized the real-time control of electronic thermostat.5. Carried out experiment research to test and verify the practicability of electronic thermostat fuzzy control strategy, in both steady control process and dynamic control process.