Research On The Control Technology Of Wet Automatic Clutch For Commercial Vehicles

With the development of automatic transmission technology,the number and the share of automatic transmission has increased year by year in our country.Because of the advantages of safety,comfort,power of the vehicle,and driver's labor intensity,the automatic transmission system has become the trend of automobile technology development.In the process of driving,commercial vehicles had a heavy workload and complex operating environment,which is easy to cause heavy work and driver's fatigue,then affected the safety of vehicles.Therefore,the application of automatic transmission products in commercial vehicles has a good market prospects.The automatic clutch installed the electronic control unit to manual transmission and controlled the separation and the engagement of the clutch.The automatic clutch does not change structure of the original transmission,and has the advantages of easy installation,low cost and simple operation,therefore it is suitable for heavy commercial vehicles.At the present time,the development of automatic clutch mainly used dry clutch in China and overseas.Compared with dry clutch,the wet clutch has obvious advantages in service life,work stability,control ability and so on.Application of wet clutch in automatic clutch product will be able to improve the performance of automatic clutch.Although AMT electronic control technology is very mature,the electronic control of wet automatic clutch is obviously different from the traditional dry automatic clutch.The electronic control of wet automatic clutch is obviously different from the traditional dry automatic clutch and the AMT electric control system with dry clutch,in the control strategy,the electronic control system,etc.Therefore,the research on the control technology of wet automatic clutch for commercial vehicle is necessary.On the basis of the analyses of the current technology status of wet automatic clutch,and combined with school-enterprise cooperation projects,the control technology of wet automatic clutch for commercial vehicles is studied in detail.The major research of this paper as shown:(1)The models of commercial vehicle power system based on automatic wet clutch are established by using MATLAB.The vehicle transmission system model,body model,the controller model and the driver model are set up.A good simulation platform is built for the research of commercial vehicle control technology based on wet clutch.(2)In order to consider the impact of the driver's starting intention during the starting process,fast starting,normal starting and slow starting identification models are established,which are based on the continuous hidden markov model and Baum-Welch algorithm.The identification of the initial intention adopts forward-backward algorithm,and the accuracy of initial intention model recognition is 92% by identifying a large number of samples.Therefore,the feasibility of the method is verified.(3)Combined with the impact degree and the sliding friction work,starting control strategy of the wet automatic clutch is developed by using quadratic optimal control.Space state model is set up on the base of the analysis of the starting process and the modeling of the transmission system.The impact degree and the sliding friction work are selected as the performance functions to solve the optimal control solution of starting control variable.The combined control of wet clutch and the engine is realized.In the performance functions,the proportion of the impact degree is determined by the driver's start intention.Based on the recognition of driver's starting intention,the fuzzy inference of the proportion of the impact degree is carried out to realize the driver's intention in the starting control strategy.It can be seen from the simulation comparison results that the starting strategy balanced the impact degree and the sliding friction work,and improves the smoothness and quality of the starting process.(4)Wet clutch actuator is hydraulic actuator driven by electronic.Combined with the structure and working principle of the actuator hydraulic system,mathematical modeling and simulation analysis are carried out on the clutch pressure control valve.In order to improve the pressure precision of the clutch hydraulic actuator,the BP neural networks adaptive controller was adopted to control the wet clutch execution mechanism.The test results show that,the actual pressure is basically the same as the target pressure trajectory and the output error is reduced by using the BP neural networks intelligently controller.(5)Based on the structural characteristics of the drive system of commercial vehicle,the electronic control system and the test platform of wet automatic clutch of commercial vehicle is designed.The hardware of the electronic control unit is designed by using the XC2785 MCU as the main controller chip.Due to the adoption of modular hierarchical intelligent software architecture,the complexity of programming is reduced and the efficiency of software development has been improved.A test platform for the commercial vehicle is set up on the basis of the electronic control system.According to the different working conditions,the starting test of horizontal road is carried out.Experimental results show that wet clutch system of commercial vehicle automatic can realize the driver's intention and the starting processcontrol effect is better,the effectiveness of the wet automatic clutch control strategies is verified.In this paper,the control technology of wet automatic clutch for commercial vehicles is studied in depth by combining theoretical analysis and experimental research.It can promote the development of automatic clutch and commercial vehicle automatic transmission technology.