农具质量对拖拉机悬挂农具系统振动特性的影响

为研究不同悬挂农具质量对拖拉机+悬挂农具系统振动特性的影响,该文以常发CF700型拖拉机(常发集团)为研究对象,用仿真和试验相结合的方法,建立了拖拉机+悬挂农具系统振动微分方程和仿真模型,仿真研究了拖拉机悬挂不同质量农具时拖拉机+悬挂农具系统振动特性,得到悬挂农具质量对拖拉机+悬挂农具系统垂向振动固有频率,俯仰振动固有频率,座椅安装处垂向振动加速度,俯仰振动角加速度,前、后轮动载系数的影响规律。研究结果表明,当悬挂农具质量从0增大到1 000 kg时,拖拉机+悬挂农具系统垂向振动固有频率从3.42逐渐减小到2.74 Hz,俯仰振动固有频率从3.07逐渐减小到1.78 Hz;当行驶速度相同时,座椅安装处垂向振动加速度和俯仰振动角加速度随悬挂农具质量的增大而减小,垂向振动加速度从2.73减小到1.02 m/s2,俯仰振动角加速度从2.56减小到0.82 rad/s2;前轮动载系数从0.09增大到0.33,随悬挂农具质量的增大而增大;速度较低时,后轮动载系数从0.06减小到0.03,随农具质量的增大略有减小,速度较高时,后轮动载系数随农具质量的增大逐渐增大,从0.06增大到0.17。该研究为拖拉机减振系统的设计提供了重要参考。

Influence of implement's mass on vibration characteristics of tractor-implement system

Abstract: Tractor and implement system travels on the road at a high speed, due to the system's severe vibration, the guide wheel's static load becomes smaller and the tractor's steering stability becomes poor, and so it is easy to cause the accident. Moreover, the vibration characteristic's research of tractor and implement system is mainly concentrated in the field of operation state, but the vibration characteristic in the transportation condition is less involved. To study the influence of implement's mass on vibration characteristics of tractor and implement system, taking the CF700 tractor as the research object, combining the method of simulation with test verification, the tractor and implement system vibration model and simulation model were built up. The key parameters of CF700 tractor were measured in the self-developed experimental station. The biggest mass of the implement and the system's mass attribute parameters were determined by calculation. At different speeds, the implement's mass was changed, and the simulation was conducted using the Matlab software. Some results were obtained which included the natural frequency of vibration system in vertical and pitch directions, the acceleration root mean square (RMS) of seat in vertical direction, the angle acceleration RMS of seat in pitch direction, the front tire's dynamic load coefficient and the rear tire's dynamic load coefficient. The experiment was conducted in the identification station of Jiangsu Province. The terms of experiment were equivalent to the condition for the simulation. Through the comparison with experimental results, the simulation results were confirmed to be accurate and meet the requirement of the research. It was shown that, the natural frequency of vibration system in vertical and pitch directions decreases with the increase of the implement mass. In addition, compared with the natural frequency in vertical direction, that in pitch direction decreases faster. The vertical natural frequency reduces to 2.74 Hz from 3.42 Hz and the pitch natural frequency reduces to 1.78 Hz from 3.07 Hz. At same speed, the acceleration RMS of seat in vertical and pitch directions decreases with the increase of the implement mass. The acceleration RMS in vertical and pitch directions is concentrated in 1.5-3 m/s2 and 1.5-2.5 m/s2 ranges, respectively. The front tire's dynamic load coefficient increases with the increase of the implement mass at same speed. It increases to 0.33 from 0.09. The static load of the front tire decreases gradually with the increase of the implement's mass, and the probability that the front tire departs from the ground increases, which has a serious impact on driving safety. Compared with the front tire's dynamic load coefficient, the rear tire's dynamic load coefficient is much smaller. When the speed is slow, the rear tire's dynamic load coefficient decreases slightly from 0.06 to 0.03 with the increase of the implement mass, and when the speed is fast, the rear tire's dynamic load coefficient increases gradually from 0.06 to 0.17 with the increase of the implement mass. The excessive tire dynamic load will compact field soils and destroy the farmland's ecological environment and crop yield. The conclusion provides an important reference for the design of tractor vibration system.