油菜精量直播机凸轮摇杆式播量调节机构设计与试验

针对不同区域的油菜种植农艺差异、不同播期播量差异及播量范围变化大的生产实际,该文设计了一种输出轴与输入轴转速速比范围为0.1～0.45的凸轮摇杆式油菜精量直播机播量调节装置。解析了调节机构的基本运动原理,分析了凸轮摇杆机构凸轮轮廓曲线及从动件运动规律,所设计凸轮轮廓曲线呈纺锤形,从动件位移曲线为螺旋曲线,从动件速度变化曲线为一峰三柱点曲线,从动件角速度变化曲线为2条不同振幅与频率的正弦曲线合并而成。开展了播量调节装置速比精确性和对排种器排种性能影响试验。试验结果表明,不同输入轴转速下,速比为0.2～0.45时播量调节装置输出轴转速相对误差值对比速比为0.1～0.2时较小,平均误差低于3.8%;不同输入轴转速、种床带前进速度下播量调节装置对排种器排种性能影响较小,播量调节装置可实现油菜不同播量需求。预调播量为5 500和6 720 g/hm2进行田间试验,结果表明,油菜各行1 m内平均苗数为16和20,符合预调播量;各行苗数一致性变异系数为6.48%和8.19%,播量调节装置满足油菜对变量播种的农艺要求。

Design and experiment of cam-rocker sowing rate adjusting mechanism for rapeseed precision direct seeding machine

According to the agronomic requirements of rapeseed planting, the amount of rapeseed sowing varies in different regions and different sowing dates.Aiming at such production practice, a cam-rocker sowing rate adjusting mechanism for rapeseed precision direct seeding machine with a speed ratio of 0-0.45 was designed. The Newton-Simpson algorithm was used to draw the mechanism diagram at each moment and the basic motion principle of the adjusting mechanism was analyzed. Based on the principle of graphic method, a kinematics mathematical model of the mechanism was established with closed-loop vector equations, and the vector equations of speed and acceleration were determined to solve the transcendental equations. Combining with the swing law of the active crank of the linkage mechanism and the variation coefficient of travel speed of the cam, the sine varying putter motion law of push rod and cam profile curves were determined. The cam profile curve of the cam-rocker mechanism and the follower motion law were analyzed, the results showed that the cam profile curve was spindle shape, follower displacement curve was a spiral curve, the follower speed curve was a curve with one peak and three column points, and the angular velocity changing curve of the follower was a combination of two different sine curves with different amplitudes and frequencies. During the entire moving process of the follower, the speed and acceleration of follower were continuous, which avoided rigid impact. The cam had a rapid return characteristic and meet the design requirements. The tests of transmission accuracy of sowing rate adjusting mechanism and influence on seeding performance were carried out on JPZS-12 seed-meter test platform. The test results showed that when the rotation speed of input shaft of sowing rate adjusting mechanism ranged from 20 to 100 r/min, comparing with the ratio ranged from 0 to 0.2, the relative errors of the output rotation speed of the sowing rate adjusting mechanism was small at the speed ratio ranged from 0.2 to 0.45, the average error was less than 3.8%. Comparing with the sowing rate adjusting mechanism was not installed, the relative change of the qualified index when the seeding rate adjusting mechanism was installed at different rotation speeds and forward speeds was less than 0.5%, the change trend of test qualified index was similar, the cam-rocker sowing rate adjusting mechanism meet the different sowing rate requirements of rapeseed. Precision broad width no-tillage planter for rapeseed was selected to conduct filed experiments using sowing rate adjusting mechanism, the sowing rate was set to 5 500 and 6 720 g/hm2. In field experiments, 8 rows of the rapeseed in different areas were selected to measure the plants in 1 m, each rows chose 5 measure points, respectively. The field experiment results showed that the average numbers of plants within 1 m were 16 and 20, respectively, which meet the preset sowing rate. The coefficient of variation were 6.48% and 8.19%, respectively, which meet the rapeseed variable sowing quality requirements of precision broad width no-tillage planter for rapeseed.