Research and Design of Hydro-mechanical Continuously Variable Transmission for Tractors

A new type continuous variable transmission device, a hydro-mechanical continuously variable transmission （HMCVT） for agricultural tractors is developed, which is composed of a single planetary gear differential train, a hydraulic transmission system consisted of variable displacement pump and fixed displacement motor and a multi-gear fixed step radio transmission. Based on the analysis of types of hydrostatic mechanical transmission （HMT） and styles of hydraulic transmission, the general drive scheme for HMCVT is obtained. The method of selecting mechanical parameters and hydraulic units is explained, and the stepless speed regulation characteristic of HMCVT is analyzed. This paper also specializes the calculating method of transmission efficiency. It shows that tractors assembled with HMCVT can obtain a continuously variable speed and achieve high drive efficiency.

液压机械无级变速器机械变速机构的传动误差分析

以东方红某型号拖拉机液压机械无级变速器中的机械变速机构为研究对象,探究其传动误差随时间的变化规律,目的是减少变速器的功率损耗。利用当量啮合误差原理,建立变速器中行星齿轮组、定轴齿轮副和两者共同作用时的传动误差与时间的关系式。比较各挡位的总传动误差和行星齿轮组传动误差,得到瞬时总传动误差最大、最小的挡位以及总传动误差的主导因素。在角频率相同时,行星齿轮组传动误差和定轴齿轮副传动误差存在耦合关系。利用蒙特卡罗法,验证了研究所得规律的正确性。建立总传动误差与功率损耗的关系式,结果表明两者存在正比关系。以减小传动误差为目的,提出了减少变速器功率损耗的措施。

拖拉机多段液压机械无级变速器的神经网络PID控制

为改善配备有多段液压机械无级变速器(hydro-mechanical continuously variable transmission,HMCVT)拖拉机的动态响应性能和行驶平稳性,保证拖拉机按照目标车速稳定行驶,提高拖拉机的驾驶舒适性和作业质量,以东方红400马力轮式拖拉机为研究对象,对多段HMCVT拖拉机行驶车速进行神经网络PID控制研究。根据实际车速变化实时调节PID控制器的参数,实现对目标车速的控制。利用Matlab/Simulink仿真建模软件建立神经网络PID控制器和拖拉机传动系统模型,对多段HMCVT拖拉机进行神经网络PID控制仿真并与常规PID控制进行比较可知,神经网络PID控制器对车速控制具有更好的自适应能力和鲁棒性。研究结果可为多段HMCVT拖拉机的自动化操作控制提供参考。