Abstract: It is an important indicator for the design of the suspension system of tractors in hilly and mountainous areas to ensure the optimal matching state between traction and plowing depth when the tractor is working on hilly terrain or hard soil. Proportional electromagnets is the main component of throttle valve electromechanical conversion,  its performance is of great significance in controlling throttle opening and achieving proportional adjustment of flow rate. This article focuses on the operational requirements of the suspension system of tractors in hilly and mountainous areas and the design requirements of the hydraulic proportional valve, a pilot throttle valve proportional solenoid for adjusting the attitude of the suspension hydraulic system is designed, and the key structural parameters of proportional solenoid are calculated. A mathematical model of the solenoid is established, and the impact of Maxwell on the flow characteristics of the valve group is simulated and analyzed. At the same time, genetic algorithm was used to optimize parameters such as the thickness of the magnetic isolation guide sleeve, the angle of the magnetic isolation ring, the width of the magnetic isolation ring, and the depth of the stator core. Finally, Maxwell was used to conduct finite element analysis of the optimized proportional electromagnet before and after optimization. The simulation results revealed that the electromagnetic force of the optimized proportional electromagnet was almost parallel to the Xaxis between 1-3 mm, and had better displacement force characteristics. The mathematical model of the pilot throttle valve was established, and its dynamic and static characteristics were simulated by Simulink so as to verify the rationality of the designed proportional solenoid parameters.

Key words:  hilly and mountainous areas, tractors, electro hydraulic suspension system, hydraulic pilot throttle valve, proportional electromagnet, structure parameters

摘要： 保证丘陵山地拖拉机在起伏山地或土质较硬地块作业时的牵引力和耕深之间的最佳匹配状态是丘陵山地拖拉机悬挂系统设计的重要指标。比例电磁铁作为节流阀电—机转换的主要元件，其性能优劣对控制节流口开度、实现流量的比例调节具有重要意义。针对丘陵山地拖拉机悬挂系统作业需求和电液比例阀设计要求，设计一种用于悬挂液压系统姿态调整的先导式节流阀比例电磁铁，对其关键结构参数进行设计，建立比例电磁铁数学模型，通过Maxwell对阀组流量特性的影响进行仿真分析。同时利用遗传算法对隔磁导向套厚度、隔磁环角度、隔磁环宽度和定子铁心深度等参数进行匹配优化，通过Maxwell对优化前后的比例电磁铁进行有限元分析。仿真结果表明：优化后的比例电磁铁在1~3 mm时电磁力几乎与X轴平行，具有更好的位移—力特性。建立先导式节流阀数学模型，通过Simulink对其进行动态特性和静态特性仿真，验证所设计的比例电磁铁参数的合理性。

关键词: 丘陵山地, 拖拉机, 电液悬挂系统, 先导式节流阀, 比例电磁铁, 结构参数