Power transmission is a critical component of agricultural tractor designs and more demanding requirements have been placed on transmissions due to the complexities of their operational environments. However, economic performance is usually sacrificed in favour of using high-powered engines to satisfy the dynamic performance requirements related to power. In this study, a new power-cycle hydro-mechanical continuously variable transmission (PCHMCVT) device is proposed for use in agricultural tractors. The effects of various structural parameters on the system performance is analysed, and an evaluation index for the performance of the PCHMCVT performance is proposed. A comprehensive examination of speed regulation performance, economic performance, and dynamic performance are performed. A multi-objective optimisation design numerical model is established, which utilises the NSGA-ΙΙ multi-objective genetic algorithm to optimise the transmission. Finally, the feasibility of the optimisation results is verified by comparing and analysing the speed ratios, torque ratios and efficiency characteristics of the transmission before and after optimisation. This study provides an optimised design method for the selection of the structural parameters of the PCHMCVT to ensure competent overall performance.

中文翻译：

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农用拖拉机无级变速器动力循环水力机械参数优化

动力传输是农用拖拉机设计的关键组成部分，由于操作环境的复杂性，对传输提出了更高的要求。然而，为了满足与动力相关的动态性能要求，通常会牺牲经济性能以支持使用大功率发动机。在这项研究中，提出了一种用于农用拖拉机的新型动力循环液压机械无级变速器 (PCHMCVT) 装置。分析了各种结构参数对系统性能的影响，提出了PCHMCVT性能的评价指标。对调速性能、经济性能、动态性能进行综合考察。建立了多目标优化设计数值模型，利用NSGA-II多目标遗传算法对变速器进行优化。最后，通过对优化前后变速器的速比、扭矩比和效率特性进行对比分析，验证了优化结果的可行性。本研究为PCHMCVT结构参数的选择提供了一种优化的设计方法，以确保整体性能合格。