Research On Design Of Automotive Electronic Coolant Pump And Control Strategy Of Cooling System

In order to promote the continuous improvement of the fuel economy level of passenger vehicles in China,the department concerned jointly announced the “Parallel Management Measures for the Average Fuel Consumption of Passenger Vehicle Enterprises and New Energy Vehicles”.The energy consumption of automobiles has received more and more attention.The cooling system is one of the important subsystems of the engine,and nearly a quarter of the heat in the engine cylinder is taken away by the cooling system.Since the speed of the coolant pump and the fan are coupled to the engine speed in the conventional cooling system,it is difficult to meet the heat dissipation demand considering the energy consumption.In order to solve the above problems,it is necessary to improve the traditional cooling system,and the electric automotive components as well as the Intelligent control system are the key to solving the problem.In this paper,the combination of theoretical analysis,numerical simulation and experimental testing is used to hydraulically design the electronic coolant pump to improve the operating efficiency of the pump.The cooling system simulation model and control system are built to provide effective cooling for the engine and reduce energy consumption of the cooling system.The main research and conclusions of this thesis are as follows:1.The development and research status of automotive cooling water pump and engine cooling system are comprehensively and systematically summarized.According to the actual operation needs of the electronic coolant pump,multiple schemes of electronic coolant pump are designed from different angles based on speed coefficient method.Scheme A,Scheme B and Scheme C are designed.2.Based on the numerical simulation technology,the full flow field unsteady simulations are carried out for the three schemes of electronic coolant pumps.The internal flow characteristics and performance of the electronic coolant pump are analyzed.The results show that,under the working conditions,the efficiency prediction value of the Scheme B and the head prediction value of the Scheme C are lower than the requirements,and the highest efficiency points of the three schemes are all shifted to the large flow condition;The position of the back of the blade near the exit is especially obvious near the diffuser of the volute.With the increase of the flow rate,the area of the high-speed area is slightly reduced,and the area of the high-speed area of the scheme A is the smalest;The static pressure values of the channels are reduced.The area with the lowest static pressure is mainly concentrated at the inlet of the back of the blade.The area of the low pressure area of the scheme A and scheme C are almost equal but significantly smaler than the scheme B;Under the small flow conditions,the relative velocity distribution of the three schemes is poor.The individual flow passages of the impeller of the scheme B are almost blocked by the eddy.As the flow rate increases,the flow regimes of both scheme A and scheme C reach a relatively ideal state.The eddy in impeller of scheme B basically disappears,and the flow patterns of the scheme A and scheme C are obviously better than those of the scheme B;The number of peaks and troughs of each monitoring point is the same as the number of blades in one rotation period,and the main frequency of the pressure pulsation is double the leaf frequency,and the pressure of the scheme A The pulsation amplitude is slightly larger than the scheme B but both are significantly smaler than the scheme C.3.After comparison,it is determined that the scheme A is the optimal design scheme,and it is processed and tested.The test results show that the head and efficiency of the electronic coolant pump under the design conditions are 20.23 m and 60.2%,which meet the design requirements;Compared with the test results,the results show that the simulated value is slightly higher than the test value,the deviation is less than 2%,the calculation method is correct,and the calculation result is reliable.4.Based on Flowmaster,the steady calculation model of the electronical cooling system is established.The accuracy of the simulation model is verified based on the wind tunnel test data.The temperature distribution of the coolant under different ambient temperatures and different engine operating conditions is analyzed.Sensitivity analysis of pump speed and fan speed provides a basis for the development of subsequent control strategies.The results show that the steady simulation model of the cooling system is reliable,and the calculation deviations under the three verification conditions are less than 1%;The cooling system model can meet the cooling requirements of the engine under extreme conditions.Under normal temperature conditions,the electronic water pump and the electronic fan can provide suitable cooling for the different cooling fluids.The fan speed and the pump speed are changed.The coolant temperature has a control effect,and the fan speed has a greater influence on the temperature.5.Based on the fuzzy control principle,a dual-input and dual-output fuzzy controller is designed.The fuzzy control strategy of the engine cooling system is compared and analyzed.The calculation results of the electronically controlled cooling system and the traditional cooling system under the simulation of the cycle test conditions show that the operation cycle section and the traditional cooling system are cooled in the urban area and some suburban sections respectively.Excessive and insufficient cooling,energy consumption is large;the temperature fluctuation of the electronically controlled cooling system is smal,and the overall energy consumption is reduced by 40.6% under cyclic conditions.