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In order to solve the problems of insufficient consideration of the actual efficiency characteristics in the design stage of the hydrostatic transmission system of agricultural and forestry machinery, and the difficulty of parameter identification due to the unknown range of parameter variation in the efficiency characteristics modeling, the matching design, the parameter identification of the efficiency characteristics model and the influence of the reducer transmission ratio were studied.First of all, aiming at the "variable pump-constant motor" power transmission system of a certain type of forest fruit picking machinery, the required power was estimated based on the resistance characteristics of the whole machine when driving on soft soil road, and the variable pump and constant motor models were matched. And then, an improved Monte Carlo method (I-MCM) with adaptive change of decision variables was proposed. According to the bench test data of selected hydrostatic system, the efficiency characteristics model of hydrostatic system was established by parameter identification method. Meanwhile, the model was compared with Monte Carlo method and improved particle swarm optimization algorithm. Finally, based on the established efficiency characteristics model, the influence of the design value of reducer transmission ratio on the energy consumption of the whole machine was analyzed. The results show that I-MCM can still effectively complete parameter identification when the range of parameter variation is uncertain, and the model error after identification is 4.05%. The transmission ratio of the reducer affects the efficiency characteristics of the hydrostatic system in the process of using the whole machine. In the range of the transmission ratio design value, the two are inversely correlated. The average transmission efficiency of the optimal design scheme is 81.45%, which is 10.53% higher than the worst design scheme. The research can provide reference for characteristic evaluation and optimization design of agricultural and forestry machinery or construction machinery. [ABSTRACT FROM AUTHOR]

Particularly crucial throughout the mode transition procedure is the transmission properties of hydro–mechanical composite transmission devices. This paper describes a multipurpose power transmission device that integrates hydrostatic, hydro-mechanical, and mechanical transmission and mainly discusses the transmission characteristic optimization problem from the perspective of speed regulation characteristics, shift strategy, and efficiency characteristics. The kinematic and dynamic analysis of the transmission system, the assembly scheme, and relevant parameters of the power transmission device are analyzed, and the speed regulation characteristic curve is obtained. The shift strategy of power transmission devices involving clutches and brakes during the whole speed regulation process and the best switch time of each component are found. The efficiency expression of the static pressure system is obtained from the efficiency model of the pump-control-motor system, and the efficiency of the multi-purpose power transmission device is obtained using the efficiency definition method. The fitting curves of hydrostatic system efficiency are determined using experimental data, and the efficiency of the hydro–mechanical composite power transmission system is obtained using the conversion mechanism method. The results show that the shift quality of power transmission devices can be improved greatly by controlling the switch sequence of clutches and brakes reasonably. [ABSTRACT FROM AUTHOR]

Particularly crucial throughout the mode transition procedure is the transmission properties of hydro–mechanical composite transmission devices. This paper describes a multipurpose power transmission device that integrates hydrostatic, hydro-mechanical, and mechanical transmission and mainly discusses the transmission characteristic optimization problem from the perspective of speed regulation characteristics, shift strategy, and efficiency characteristics. The kinematic and dynamic analysis of the transmission system, the assembly scheme, and relevant parameters of the power transmission device are analyzed, and the speed regulation characteristic curve is obtained. The shift strategy of power transmission devices involving clutches and brakes during the whole speed regulation process and the best switch time of each component are found. The efficiency expression of the static pressure system is obtained from the efficiency model of the pump-control-motor system, and the efficiency of the multi-purpose power transmission device is obtained using the efficiency definition method. The fitting curves of hydrostatic system efficiency are determined using experimental data, and the efficiency of the hydro–mechanical composite power transmission system is obtained using the conversion mechanism method. The results show that the shift quality of power transmission devices can be improved greatly by controlling the switch sequence of clutches and brakes reasonably.