Speed Regulation And Power Management Strategy Of Compound Coupled Hydro-mechanical Transmission Based On Multiple Working Conditions

Some special vehicles,including wheel loaders and sprinklers,will work with dramatic load’s change generally.And they will face the problem of low efficiency,high fuel consumption and increased emissions if a conventional hydraulic mechanical transmission is used.In addition,the power required by special vehicles’ function(eg:sprinkler’s function)is provided by engines currently,which make the fuel consumption of engines increase in this situation and the energy consumed by braking cannot be recycled.Though the electric motor can also recycle energy,the efficiency of its recycle is relatively low.In order to solve these problems,in this paper,a novel Compound Coupled Hydro-mechanical Transmission(CCHMT)proposed by our team is equipped to special vehicles,a new type of energy recycle/reuse system is designed and Dynamic Programming algorithm is used to optimize basic speed regulation strategy under certain working conditions.CCHMT has relatively excellent speed regulation characteristics,torque characteristics,efficiency characteristics and power split characteristics.According to the needs of the vehicle,it can realize real-time continuous variable speed regulation.Compared with other types of CVT,the CCHMT has higher efficiency and power density.The energy storage part of the energy recycle/reuse system is connected to the hydraulic part of CCHMT,which makes it can recycle energy when braking.In this paper,the energy recycle/reuse system is designed and analyzed in terms of the structure,working principle and characteristics of CCHMT,the proper driving strategy of special vehicle is proposed according to the characteristics of these two systems.In line with physical conditions,the models of the vehicle’s parameters,the driving resistance force,the diesel engine and working conditions are established,the parameters of hydraulic energy accumulator and the model of energy recycle/ reuse system is also established according to models mentioned above.The simplified model of torque converter is constructed in order to make the CCHMT and engine match better.The dynamic programming algorithm was used to formulate the theoretical speed regulation strategy under specific working conditions.The discrete models of the above models were established according to the algorithm rules and optimized for each model based on the algorithm rules.The appropriate constraint conditions and penalty functions were selected to ensure the rationality of the solution.The research results indicate that the proposed DP optimized speed regulation strategy has good performance on fuel economy and speed regulation;The energy recycle/ reuse system can greatly improve the fuel economy of special vehicles during certain working conditions up to 23.91%,and can recycle up to 2.03% of the energy consumed during braking.According to the simulation results,the speed regulation strategy under different accelerations can provide a basis for simplifying the control strategy of the vehicle transmission system,and provide a new method for the subsequent development of the full-duty control strategy of the special vehicle equipped with CCHMT.