Research On Slip Control System Of Lock-up Hydraulic Torque Converter Of Loader

The working conditions of the loader are complicated,and the energy consumption problem is serious.The loader can switch the hydraulic and mechanical working conditions of the transmission system through the unlocking and locking control of the lock-up hydraulic torque converter to improve the transmission efficiency,but the impact of the unlocking and locking control process is large,resulting in poor ride comfort of the whole machine.In this thesis,aiming at the contradiction between the fuel economy and ride comfort of the loader,the lock-up hydraulic torque converter is taken as the research object,and the slip condition between the hydraulic and mechanical working conditions is taken as the entry point,and the slip control system of loader is studied.Firstly,based on the structural characteristics and working principle of the lock-up hydraulic torque converter,the working process of the lock-up clutch is studied,the nonlinear dynamic model of hydraulic,slip and mechanical working conditions is established,and the electro-hydraulic execution system of the lock-up hydraulic torque converter is designed,and the hierarchical structure of the slip control system of the lock-up hydraulic torque converter for loader is established.Secondly,aiming at the problem of unclear "hydraulic-slip-mechanical" control boundary of hydraulic torque converter,a fuzzy comprehensive decision-making method for slip control area is proposed.Aiming at the characteristics of the cycle operation of the loader,the factor set and evaluation set of decision-making in the control area are established,and the weight of the factor set is studied by the analytic hierarchy process,and the membership degree of each parameter to the control area is established,based on this,the fuzzy relation matrix between each parameter and the control area is constructed.Using the fuzzy comprehensive evaluation method,the five-parameter fuzzy comprehensive decision-making of engine speed,accelerator pedal opening,speed ratio,gear position and vehicle speed in the control area is realized.Thirdly,aiming at the problem of large impact in the unlocking and locking control process of lock-up clutch of hydraulic torque converter,a fuzzy reasoning neural network slip control method is proposed.Through theoretical research on the impact factors of the unlocking and locking control process impact,a fuzzy reasoning system with the actual slip speed and accelerator pedal opening as input is established to realize the dynamic reasoning of the slip control target.On this basis,the neural network control is improved,and the impact degree is controlled within the allowable range..Then,aiming at the problem of incomplete control strategy of torque converter after considering slip conditions,a control strategy of slip control system is proposed.In-depth research on the conversion mechanism of the "hydraulic-slip-mechanical" three working conditions,combined with the slip control area decision-making and slip control method,research the logic flow of the control area decision-making and conversion,slip control and electro-hydraulic execution process,so as to Based on this,the control strategy of the slip control system is established.Finally,based on the above research on slip control area decision-making,slip control method and control strategy,a co-simulation model of loader lock-up hydraulic torque converter slip control system is established.According to the characteristics of the working conditions of the loader,the operation cycle is subdivided and reclassified into four typical control system action stages,and the effect of each stage and the entire V-shaped operation cycle slip control system is verified,and after considering the slip condition,the fuel economy and ride comfort of the loader are studied.The results show that after the introduction of the slip control system,the total fuel consumption of the loader is basically the same as the original scheme,the friction time of the lock-up clutch is extended by 0.61s～2s,and the impact is reduced by 92.3%.The loader lock-up hydraulic torque converter slip control system improves the ride comfort of the whole machine while ensuring fuel economy,provides theoretical basis for the automatic control of torque converter under three operating conditions and technical support for solving the contradiction between fuel economy and ride comfort of loader.