气力式油菜精量联合直播机振动特性及对排种性能影响

Vibration characteristics of pneumatic combined precision rapeseed seeder and its effect on seeding performance

针对气力式油菜精量联合直播机受内外激励产生振动影响排种器工作性能的问题,开展了直播机田间作业振动特性测试与分析,搭建振动排种试验台进行了排种器性能振动影响研究。田间测试的振动信号时域分析结果表明,机具垂直方向振动远大于水平横向和前进方向,在未耕地表作业振动大于已耕地表,振动幅值随发动机转速、旋耕转速、前进速度的增大而增大。建立了垂直方向振动加速度均方根值与发动机转速、旋耕转速和前进速度的多元线性回归模型,标准偏回归系数分析表明,未耕地旋耕转速和前进速度是影响整机振动幅值的主要因素,已耕地旋耕转速是影响整机振动的主要因素。振动信号频域分析发现,整机振动主频分布在0~150 Hz以内,频率分布与发动机、旋耕装置工作转速的倍频有关,受前进速度和地表状态影响不大。振动台架试验结果表明,振动会降低较大负压水平时的型孔重吸率,振频为10、20 Hz时,振动会显著降低排种合格指数,适当的中频振动能提高低吸种负压时的吸种概率,不同振动工况下的吸种临界负压值存在差别。该研究为油菜精量联合直播机作业性能优化与提升提供了基础参数。

Vibrations of pneumatic combined precision rapeseed seeder by internal and external excitation will affect the performance of seeder.In this study,the vibration characteristics of the direct seeder were measured and analyzed through field test,and the influence of the vibration characteristics on seeder performance was investigated by vibration seeding test bench.Time-domain analysis results of vibration signals tested in the field showed that the vertical vibration of the machine is much significant than the horizontal and forward direction,while the vibration on the uncultivated land is larger than that on the cultivated land.Furthermore,the amplitude of vibration increases with the increase of engine speed,rotary tillage speed and forward speed.A multiple linear regression model was established between the RMS value of vertical vibration acceleration and engine speed,rotary tillage speed and forward speed.The standard partial regression coefficient analysis showed that the rotary tillage speed and forward speed for uncultivated land are the main factors affecting the vibration amplitude of the machine.On the other hand,for cultivated land,the rotary tillage speed influenced the most on the machine vibration.Frequency domain analysis of vibration signals showed that the main frequency of vibration of the seeder was within 0~150Hz,and the frequency distribution was related to the frequency multiplications of the working speed of engine and rotary tillage,but was hardly influenced by forward speed and the ground state.The vibration bench test results showed that vibration could reduce the multiple seeds holding probability at high level of negative pressure.When vibration frequency were 10 Hz and 20 Hz,the qualified index of seed metering device was significantly reduced.It was also observed that appropriate medium frequency vibration could improve single seed holding probability under negative pressure.What’s more,the critical negative pressure of seed holding was variant under different vibration conditions.The results can provide basic parameters for optimization and improvement of operation performance of combined precision rapeseed seeder.