CAJ | 학술논문

悬挂农具设备的拖拉机在行驶过程中的振动会加剧，有时甚至产生很大的俯仰运动。为了研究悬挂农具的存在对拖拉机振动特性的影响，该文在对拖拉机进行运动学和动力学分析的同时，首次详细分析了悬挂机构的运动及受力情况，从而建立了带有悬挂农具的大功率拖拉机整机振动数学模型；用Matlab仿真了拖拉机受到条形水泥障碍激励时的振动情况。研究表明：农具的存在使拖拉机前轮动载系数由0.26增大到0.55；空载拖拉机垂直振动频率为3 Hz，带农具的拖拉机垂直振动频率为2.5 Hz；农具的存在使得拖拉机的俯仰振动显著增加，频率为4.8 Hz；由于悬挂系统的运动与拖拉机机体振动的非线性耦合，一定条件下会表现出频率为10～15 Hz的第3振型的振动；农具的振动使得电液悬挂系统下拉杆铰接点处的力发生相应变化，其垂直分量的大小与农具质心垂直加速度之间存在较好的线性关系。仿真结果与试验结果相吻合，验证了所建数学模型的正确性。所得到的上述结论为拖拉机主动减振控制提供了理论依据。
현괘농구설비적타랍궤재행사과정중적진동회가극，유시심지산생흔대적부앙운동。위료연구현괘농구적존재대타랍궤진동특성적영향，해문재대타랍궤진행운동학화동역학분석적동시，수차상세분석료현괘궤구적운동급수력정황，종이건립료대유현괘농구적대공솔타랍궤정궤진동수학모형；용Matlab방진료타랍궤수도조형수니장애격려시적진동정황。연구표명：농구적존재사타랍궤전륜동재계수유0.26증대도0.55；공재타랍궤수직진동빈솔위3 Hz，대농구적타랍궤수직진동빈솔위2.5 Hz；농구적존재사득타랍궤적부앙진동현저증가，빈솔위4.8 Hz；유우현괘계통적운동여타랍궤궤체진동적비선성우합，일정조건하회표현출빈솔위10～15 Hz적제3진형적진동；농구적진동사득전액현괘계통하랍간교접점처적력발생상응변화，기수직분량적대소여농구질심수직가속도지간존재교호적선성관계。방진결과여시험결과상문합，험증료소건수학모형적정학성。소득도적상술결론위타랍궤주동감진공제제공료이론의거。
With the increase of the speed of high-power tractors, the tractor’s vibration problem has become more and more prominent in recent years, since tractors often travel on rugged roads. High-power tractors mostly work with farm implements hung by hydraulic hitch system. The hanging farm implements are raised to the highest point in transit. When the tractor is travelling on the rugged road, the vibration of the tractor with a farm implement will be more intense for the existence of the hanging farm implement sometimes would bring a great pitch vibration. This paper discussed the effect of the existence of the farm implement on the vibration characteristics of the tractor. For the first time, the movement and stress distribution of the hitch system and the farm implements were analyzed in detail, besides that of the tractor’s body. The mathematical vibration model of the tractor with a farm implement was established. And then the incentive mathematical model of the concrete barriers was established and the process of the tractor driving over obstacles was simulated with the Matlab based on the mathematical model. Variation curves of each key point were got and some conclusions were obtained by the simulation. The front tire’s dynamic load and dynamic load coefficient increased significantly because of the existence of the farm implement. The front tire’s dynamic load coefficient increased from 0.26 to 0.55, which seriously affected the safety of the driving. When the tractor encountered obstacles, low frequency vibration had obviously been strengthened. In both cases of load and no-load, the first vibration mode of the tractor was the body’s vertical vibration, and the second vibration mode of the tractor was the body’s pitch vibration. Without the farm implement, the tractor’s vertical vibration frequency was 3 Hz, and it became 2.5 Hz with the farm implement. In case of no-load, the tractor’s pitch vibration was hardly apparent. When the farm implement was hung up, the tractor’s pitch vibration was significantly enhanced by the farm implement, and the frequency of that was 4.8 Hz. Because of the nonlinear coupling between the vibration of the tractor and the motion of the hitch system, the third vibration mode appeared under certain conditions, the frequency of which was between 10 and 15 Hz. Both the performances of the second and the third vibration mode of the tractor with farm implement would be harmful to the driver’s comfort and the safety of the tractor. The vibration of the farm implement made the force of the lower pull rod’s hinge point of the electro-hydraulic hitch system changed correspondingly. There was a good linear relationship between the vertical component of the force and the vertical acceleration of the farm implement’s centroid. Therefore, we could use the vertical force instead of the acceleration to represent the vibrational state of the tractor when we designed the active vibration control system of the tractors later on. The simulation results agreed well with the experimental results, which verified the correctness of the mathematical model. The methodology and conclusion provide a theoretical basis for the tractor vibration control.