油菜高速气送式双变量供种装置设计与试验

Design and Experiment of High-speed Air-assisted Bi-variable Seed Supply Device for Oilseed Rape

摘要:

针对现有油菜气送式机直播作业中供种装置在不同作业速度下的适配性以及供种精度低等问题，设计了一种油菜高速气送式双变量供种装置，通过“变型孔长度+变转速”的方式，实现大范围精量供种。在阐明供种装置工作原理基础上，构建种子供-携-投3阶段运动学模型，确定型孔结构、排种槽轮转速、型孔长度等关键结构及运行参数。通过台架试验研究了转速-型孔长度-供种速率关系模型，由此构建了不同播量、不同作业速度条件下的排种转速、型孔长度双变量调控策略。开展单双变量供种性能对比试验，台架试验结果表明，当双变量供种装置转速为15~70r/min时，供种精度不低于93.3%，相比单变量式，供种精度提升8.2个百分点；单变量与双变量式供种速率为35.7~123.2g/min、37.3~286.0g/min，当播量为2.25~6kg/hm2时，双变量供种装置供种精度更高。播种性能路面试验结果表明，在相同播量，不同作业速度下，供种精度为90.61~97.69%，同行播量稳定性变异系数为1.69%~3.90%，符合国家标准和相关行业标准要求。田间试验结果表明，当播量为2.25~5.25kg/hm2、作业速度为3~12km/h时，供种精度最高可达97.6%，各行播量一致性变异系数和播量稳定性变异系数不大于11.1%和9.5%，双变量供种装置可满足油菜气送式机直播精量供种作业要求。

Abstract:

Aiming at the adaptability of the seed supply device at different operating speeds and the lack of seed supply precision in the existing air-assisted direct seeding operations for oilseed rape，a high-speed air-fed bi-variable seed supply device for oilseed rape was designed. This device achieved a wide range of precise seed supply by combining “variable aperture length + variable rotational speed”. Based on elucidating the working principle of the seed supply device, a three-stage kinematic model of seed supply-carrying-dropping was established. Key structural and operational parameters, such as aperture structure, rotational speed of the seed metering groove wheel, and aperture length were determined. Through bench tests, the relationship model among rotational speed, aperture length, and seed supply rate was studied, and a bi-variable control strategy for seed metering rotational speed and aperture length was constructed at different sowing rates and operating speeds. Comparative experiments on single-variable and bi-variable seed supply performance were conducted. The bench test results showed that the bi-variable seed supply device achieved a seed supply accuracy of no less than 93.3% within the rotational speed range of 15~70r/min, which was 8.2 percentage points higher than that of the single-variable type. The seed supply rate ranged for the single-variable and bi-variable types were 35.7~123.2g/min and 37.3~286.0g/min, respectively. The bi-variable seed supply device demonstrated higher seed supply precision within the range of 2.25~6kg/hm2. Furthermore, the road test results for sowing performance indicated that, at the same seeding rate and different operating speeds, the seed supply accuracy ranged from 90.61% to 97.69%, and the coefficient of variation for the uniformity of sowing rate among rows ranged from 1.69% to 3.90%, meeting the national standards and relevant industry requirements. Field test results showed that, within the sowing rate range of 2.25~5.25kg/hm2 and operating speeds of 3~12km/h, the seed supply accuracy can reach up to 97.6%. The coefficients of variation for the consistency of sowing rate among rows and the stability of sowing rate were no more than 11.1% and 9.5%, respectively. The bi-variable seed supply device can meet the requirements for precision seed supply in air-assisted direct seeding operations for oilseed rape.