Improvement On The Performance Of A Light Bus Heating System

With the social and automobile industry development,the customers have higher requirements for the comfort of motor vehicles,with the demand for the vehicle heating system performance gradually raised.There are different types of vehicle heating systems,with the engine cooling water heating system,which is simple and low in cost,adopted in most vehicles.With a light bus of China IV model having been launched,its heating system performance in the northern region became the main complaint of customers.Especially in the low engine speed range from idle to 1500r/min,the warm wind at the outlet port of warm wind can hardly felt.The light bus adopts the engine cooling water heating system widely adopted in the market,with its heating performance obviously inferior to the competitive vehicle and not being able to meet the requirements of the customers.In this paper,the following researches are carried out on the engine cooling water heating system for solving the problem with the light bus heating system performance not being able to meet the requirements of customer in the cold regions:1.Theoretical analysis of heating system demand and effective heat supply is performed,with the engine heat supply under certain test conditions compared with the heat demand for meeting the heating system performance requirement.2.The heating system of the vehicle studied is compared with that of the competitive vehicle in terms of the heating system layout structure and the test dada of the system flow,the temperature increase speed of the engine cooling water and the temperature of air at the outlet port of the warm air,finding out the differences and the clues for making the improvements on the heating system.3.KULI software is applied to construct the heating system simulation model of the light bus,whose accuracy is verified by comparing the simulation results with the test data.The influences of different factors on the heating system performance are studied with the model,revealing the improvement directions.4.Based on improving engine coolant temperature and heating system coolant flow,the improvements on the degassing cycle structure,pipe insulation,engine water pump speed ratio and heating system layout structure are performed and a four-way valve is designed for ensuring that the EGR cooler function is not affected.5.The coolant flow and cold regions heating performance tests of the optimized heating system are performed,with the results showing that the optimized heating system performance achieves the design goal,whose heating performance is equivalent to that of the competitive vehicle.Through the researches of this paper,the reasons for the poor heating performance of the vehicle are found out and the effective improvement measures are taken,making the heating performance of the vehicle meet the customer requirements and improve its competitiveness.The researches done have a reference value for the development of similar vehicle heating systems.