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雙腔氣力式水稻精量水田直播機(jī)設(shè)計(jì)與試驗(yàn)

2020-03-04 13:10:42張國(guó)忠韓宇航查顯濤
關(guān)鍵詞:氣力稻種種器

邢 赫,張國(guó)忠,韓宇航,高 原,查顯濤

雙腔氣力式水稻精量水田直播機(jī)設(shè)計(jì)與試驗(yàn)

邢 赫,張國(guó)忠※,韓宇航,高 原,查顯濤

(1. 華中農(nóng)業(yè)大學(xué)工學(xué)院,武漢 430070;2. 農(nóng)業(yè)農(nóng)村部長(zhǎng)江中下游農(nóng)業(yè)裝備重點(diǎn)實(shí)驗(yàn)室,武漢 430070)

雜交水稻分蘗能力強(qiáng),產(chǎn)量高。為滿足雜交水稻水田直播需求,該研究以3~5粒/穴為播種目標(biāo),設(shè)計(jì)了一種雙腔氣力式水稻精量直播機(jī)。介紹了雙腔氣力式水稻精量直播機(jī)主要工作部件結(jié)構(gòu),并對(duì)負(fù)壓風(fēng)力系統(tǒng)進(jìn)行選型與設(shè)計(jì)。以雜交稻甬優(yōu)4949為試驗(yàn)對(duì)象,以吸種負(fù)壓與直播機(jī)前進(jìn)速度為影響因素進(jìn)行了田間試驗(yàn)。試驗(yàn)結(jié)果表明:當(dāng)吸種負(fù)壓為3.2 kPa、直播機(jī)前進(jìn)速度為0.2~0.4 m/s時(shí),10行排種器平均播種合格率(3~5粒/穴占比)為91.04%,0~2粒/穴占比2.23%,大于5粒/穴占比6.73%,各排種器之間的播種合格率變異系數(shù)為1.24%,滿足雜交稻田間播種作業(yè)要求,為水田精量直播提供了參考依據(jù)。

農(nóng)業(yè)機(jī)械;設(shè)計(jì);直播機(jī);氣力式;雜交稻;雙腔;精量播種

0 引 言

水稻是中國(guó)主要糧食作物之一,也是全球超過(guò)50%的人口主食[1]。目前中國(guó)水稻種植以雜交稻為主[2-4],相比于常規(guī)稻,雜交稻具有較強(qiáng)分蘗能力與較高的產(chǎn)量[5-6],采用機(jī)械化直播種植時(shí),僅需3~5粒/穴即可形成高產(chǎn)群體結(jié)構(gòu)[7];同時(shí)由于雜交稻稻種成本較高,采用機(jī)械化精量播種可顯著節(jié)約播種量[8-9]。

水稻機(jī)械化直播技術(shù)主要分為撒播、條播和穴播。撒播播種精度低,播種量大,稻種田間分布無(wú)規(guī)律,出苗均勻性差,不利于水稻生長(zhǎng)與水稻管理;相比于撒播,條播的稻種分布規(guī)律性提高,但播種量仍較大,主要用于常規(guī)稻播種,不滿足雜交稻精量播種需要[10-11]。穴直播采用精量排種器對(duì)水稻進(jìn)行精量穴播,播種精度高,田間分布均勻,有利于提高水稻產(chǎn)量。Zhang等[12]設(shè)計(jì)了一種組合型孔機(jī)械式精量穴播機(jī),采用2種型孔對(duì)稻種進(jìn)行精量播種,該機(jī)目前已廣泛應(yīng)用于中國(guó)多個(gè)省份。田立權(quán)等[13]設(shè)計(jì)了一種勺輪式水稻穴播機(jī),采用勺輪機(jī)構(gòu)對(duì)稻種進(jìn)行取放,形成穴播。為滿足精少量均勻播種需求,國(guó)內(nèi)外學(xué)者也針對(duì)氣力式播種技術(shù)進(jìn)行了深入研究。明哲等[14]設(shè)計(jì)了一種氣吸式水稻排種器,采用虛擬樣機(jī)技術(shù)與離散元仿真分析法對(duì)其氣室結(jié)構(gòu)進(jìn)行了分析,獲取了氣壓穩(wěn)定性對(duì)吸種精度的影響規(guī)律,提升了氣流對(duì)種子的吸附作用,提高了吸種穩(wěn)定性與精度。戴億政等[15]設(shè)計(jì)了一種氣吹式水稻直播機(jī),采用正壓氣流將水稻種子播種田間,但由于播種量較大,無(wú)法適用于精量播種。張開(kāi)興等[16]設(shè)計(jì)了一種孔徑可變雙盤氣吸式排種器,采用雙盤相互疊加原理變換孔徑,為提高吸種精度與穩(wěn)定性,優(yōu)化了吸孔倒角,通過(guò)試驗(yàn)得到了最佳吸孔倒角。張順等[17]設(shè)計(jì)了一種旱地水稻精量直播機(jī),優(yōu)選了最佳工作參數(shù),田間驗(yàn)證試驗(yàn)顯示可滿足旱地水稻種植要求。Ibrahim等[18]設(shè)計(jì)了一種多行氣吸式直播機(jī),采用多排吸孔結(jié)構(gòu)同時(shí)對(duì)種子進(jìn)行吸附,并采用不同的排種管對(duì)種子進(jìn)行分配,實(shí)現(xiàn)了單個(gè)排種器多行同時(shí)工作的效果,但由于該排種器采用管路分配種子,因此對(duì)種子球度及流動(dòng)性要求較高,對(duì)水稻播種時(shí)精度與均勻性不高。Yatskul等[19-20]對(duì)排種器的氣力輸送系統(tǒng)的均勻性進(jìn)行了理論分析與建模,分析了管路結(jié)構(gòu)對(duì)氣流均勻性的影響,建立了種子與氣流之間的關(guān)系模型,為氣力式排種器的氣固耦合研究提供了基礎(chǔ)。Wang等[21]針對(duì)超級(jí)雜交稻的播種需求,設(shè)計(jì)了一種氣力滾筒式排種器與直播機(jī),采用滾筒對(duì)稻種進(jìn)行精量吸附,并通過(guò)正壓對(duì)稻種進(jìn)行運(yùn)移使其落入田間,由于稻種在管路內(nèi)部的運(yùn)動(dòng)難以控制,因此田間播種成穴效果有待提高。Karayel等[22]針對(duì)氣流與種子之間的相互影響機(jī)理進(jìn)行了研究與分析,建立了不同參數(shù)與結(jié)構(gòu)下的種子運(yùn)動(dòng)模型。Zhang等[23]針對(duì)水稻芽種設(shè)計(jì)了一種氣力式排種器,建立了吸附模型,分析了稻種吸附機(jī)理,為精量播種提供了研究基礎(chǔ)。Xing等[24]針對(duì)超級(jí)雜交稻播種要求,設(shè)計(jì)了一種單圓盤氣力式直播機(jī),理論播種精度為1~3粒/穴,田間播種時(shí)受大田環(huán)境影響,存在空穴率較高風(fēng)險(xiǎn)。Singh等[25]對(duì)影響氣力式排種器吸種精度的主要因素進(jìn)行了分析,明確了各個(gè)因素之間的相互影響與相互作用的關(guān)系,建立了吸種模型,為優(yōu)化結(jié)構(gòu)參數(shù)提供了依據(jù)。

以上水稻精量直播技術(shù)的研究中,機(jī)械式排種器播種量大,難以滿足精少量雜交稻播種的需求;氣力式排種器的研究主要集中于室內(nèi)試驗(yàn),缺乏田間試驗(yàn)研究與性能驗(yàn)證。為滿足雜交水稻田間直播需求,本文以3~5粒/穴播種量為目標(biāo),設(shè)計(jì)了一種雙腔氣力式水稻精量直播機(jī),介紹了該機(jī)主要結(jié)構(gòu)與設(shè)計(jì),試制樣機(jī)并進(jìn)行了田間試驗(yàn),對(duì)田間作業(yè)參數(shù)進(jìn)行優(yōu)選,滿足了雜交稻田間精量播種的要求。

1 總體結(jié)構(gòu)與工作原理

雙腔氣力式水稻精量直播機(jī)總體結(jié)構(gòu)如圖1所示。該機(jī)主要由洋馬(VP6D)動(dòng)力底盤(其功率為13.2 kW)、開(kāi)溝底板、雙腔氣力式水稻精量排種器、負(fù)壓管路、動(dòng)力輸出軸(Power Take Off shaft, PTO)、三點(diǎn)懸掛裝置、仿形浮板、汽油旋渦風(fēng)機(jī)等部件構(gòu)成,其主要技術(shù)參數(shù)如表1所示。

1.洋馬插秧機(jī)(VP6D)動(dòng)力底盤 2.開(kāi)溝底板 3.雙腔氣力式水稻精量排種器 4.負(fù)壓分支管路 5.動(dòng)力輸出軸 6.三點(diǎn)懸掛裝置 7.負(fù)壓總管路 8.仿形浮板 9.汽油旋渦風(fēng)機(jī) 10.開(kāi)種溝器 11.開(kāi)蓄水溝器 12.開(kāi)排水溝器

表1 雙腔氣力式水稻精量直播機(jī)主要技術(shù)參數(shù)

如圖1所示,雙腔氣力式水稻精量直播機(jī)的核心工作部件雙腔氣力式水稻精量排種器通過(guò)機(jī)架等結(jié)構(gòu)安裝于洋馬插秧機(jī)動(dòng)力底盤的后部,采用三點(diǎn)懸掛機(jī)構(gòu)對(duì)播種機(jī)架進(jìn)行提升與下降;各排種器之間由聯(lián)軸器相互連接,實(shí)現(xiàn)同軸轉(zhuǎn)動(dòng)、同步播種,并通過(guò)洋馬動(dòng)力底盤的PTO為排種器的轉(zhuǎn)動(dòng)提供動(dòng)力輸出,排種器與動(dòng)力輸出軸之間通過(guò)減速箱相互連接,實(shí)現(xiàn)播種速度與前進(jìn)速度匹配。選用汽油旋渦式風(fēng)機(jī)為雙腔氣力式排種器提供吸種負(fù)壓,通過(guò)調(diào)節(jié)汽油旋渦風(fēng)機(jī)油門開(kāi)度調(diào)節(jié)輸出功率進(jìn)而實(shí)現(xiàn)對(duì)負(fù)壓壓強(qiáng)的控制,以滿足雙腔氣力式水稻精量直播機(jī)的吸種負(fù)壓要求。開(kāi)溝底板在田間開(kāi)出播種溝、蓄水溝和排水溝,排種器田間作業(yè)時(shí)將水稻種子播于播種溝內(nèi),蓄水溝用于儲(chǔ)存一定量的水以保證田間的泥面濕潤(rùn),排水溝方便排出多余的水,以免田間積水過(guò)多過(guò)深,影響稻種發(fā)芽。

2 關(guān)鍵部件設(shè)計(jì)

2.1 播種裝置設(shè)計(jì)

2.1.1 排種器總體結(jié)構(gòu)

雙腔氣力式水稻精量排種器結(jié)構(gòu)如圖2所示,主要由種箱、種箱連接件、排種殼體、排種軸、卸種裝置、氣吸殼體、法蘭和吸種盤組成。主要技術(shù)參數(shù)如表2所示。

1.種箱 2.進(jìn)種通道 3.排種殼體 4.排種軸 5.卸種裝置 6.排種管 7.氣吸殼體 8.法蘭 9.吸種盤

表2 雙腔氣力式水稻精量排種器主要技術(shù)參數(shù)

如圖2所示,稻種由雙種箱經(jīng)由各自的種箱連接件流入到雙排種殼體中,分別進(jìn)入左右排種殼體的吸種區(qū)內(nèi)。氣吸殼體與雙吸種盤相互配合形成氣室結(jié)構(gòu),氣流由氣吸殼體的負(fù)壓接口流入氣室中,使氣室內(nèi)部產(chǎn)生負(fù)壓,在雙吸種盤吸孔處產(chǎn)生壓差,將吸種區(qū)內(nèi)的稻種吸附于吸孔上。吸孔之間安裝攪種裝置,在攪種裝置的作用下,吸種區(qū)內(nèi)的稻種更加松散,有利于提高稻種的被吸附率。采用單軸雙法蘭結(jié)構(gòu)帶動(dòng)雙吸種盤轉(zhuǎn)動(dòng),被吸附的稻種隨雙吸種盤轉(zhuǎn)動(dòng),經(jīng)過(guò)攜種區(qū)到達(dá)投種區(qū),投種區(qū)與負(fù)壓氣室分離,當(dāng)?shù)痉N到達(dá)投種區(qū)后,所受負(fù)壓吸力消失,在重力的作用下離開(kāi)吸種盤,由于雙吸種盤吸孔相互對(duì)應(yīng),可同時(shí)投種,完成整個(gè)播種過(guò)程。

2.1.2 氣吸殼體結(jié)構(gòu)設(shè)計(jì)

氣力式排種器的氣壓由風(fēng)機(jī)通過(guò)管路流入氣吸殼體的流道內(nèi)部,流道與吸種盤相互配合,在吸孔處產(chǎn)生壓差,進(jìn)行吸種作業(yè),因此,流道內(nèi)部氣壓的均勻性將直接影響吸孔氣壓的均勻性。如圖3a所示,與單吸種盤氣力式排種器不同,雙腔氣力式排種器采用雙吸種盤進(jìn)行吸種,氣室流道的兩側(cè)面均有吸孔。雙吸種盤上12組吸孔數(shù)量相同且吸孔位置相互對(duì)稱,采用同軸傳動(dòng),可實(shí)現(xiàn)同步吸種與同步落種。

1.負(fù)壓接口 2.吸孔 3.負(fù)壓氣室流道 4.吸種盤 5.大氣壓接口 6.大氣壓氣室流道 7.吸種盤底面 8.氣室流道內(nèi)壁

如圖3b所示,負(fù)壓流道為U型結(jié)構(gòu),根據(jù)前期研究結(jié)果[26],負(fù)壓接口位于流道中間,使氣流更加均勻在流道內(nèi)部分布,當(dāng)流道寬度大于14 mm,厚度大于20 mm時(shí)可有效減小氣流在流道內(nèi)部的壓損[26],因此,流道的寬度設(shè)置為24 mm,厚度設(shè)置為30 mm。根據(jù)流體力學(xué)原理[27],當(dāng)氣流在氣室內(nèi)部流動(dòng)時(shí)與氣室內(nèi)壁產(chǎn)生摩擦,造成氣壓的損失,同時(shí)氣室的局部拐角也會(huì)造成氣壓的局部損失,因此,將氣室流道的結(jié)構(gòu)設(shè)計(jì)成圓弧狀,圓弧角度為240°,以減小壓損。

2.1.3 吸種盤結(jié)構(gòu)設(shè)計(jì)

為了滿足雜交稻3~5粒/穴的播種要求,將每一側(cè)吸種盤均開(kāi)設(shè)2排吸孔,2側(cè)共有4排吸孔。吸種盤結(jié)構(gòu)如圖4所示。為了提高稻種的吸附率,在2個(gè)吸孔之間安裝攪種裝置,攪種裝置為圓柱體,厚度2 mm,直徑5 mm,該裝置與2個(gè)孔圓相切。根據(jù)文獻(xiàn)[10]可知,增加攪種裝置可增加稻種在吸種區(qū)留的流動(dòng)性,可輔助吸孔吸附稻種。根據(jù)前期研究結(jié)果[10],將吸種盤直徑設(shè)置為152 mm,厚度為2 mm,吸孔直徑為1.5 mm,吸孔組數(shù)為12組。

2.1.4 排種性能預(yù)試驗(yàn)

為了測(cè)試排種器的播種效果,在吸種盤轉(zhuǎn)速30 r/min的條件下進(jìn)行了預(yù)試驗(yàn),以3~5 粒/穴為合格指標(biāo),結(jié)果如圖5所示,由試驗(yàn)結(jié)果可知,當(dāng)吸種負(fù)壓小于1.6 kPa或大于4.0 kPa時(shí),播種合格率低于72%,與設(shè)計(jì)精量播種目標(biāo)差距較大,當(dāng)吸種負(fù)壓為3.2 kPa時(shí),3~5粒/穴率高于85%,由預(yù)試驗(yàn)結(jié)果表明該排種器滿足雜交稻3~5粒/穴的播種需求。

1.吸種區(qū) 2.清種區(qū) 3.攪種裝置 4.吸孔 5.攜種區(qū) 6.送種區(qū)

圖5 預(yù)試驗(yàn)結(jié)果

2.2 負(fù)壓風(fēng)力裝置

該直播機(jī)選用本田2200汽油旋渦式風(fēng)機(jī)為雙腔氣力式直播機(jī)的排種器提供吸種負(fù)壓,如圖6a所示。該汽油旋渦風(fēng)機(jī)的功率為4.125 kW,最大真空壓強(qiáng)為25 kPa,流量為200 m3/h,通過(guò)控制油門開(kāi)度調(diào)節(jié)輸出功率進(jìn)而實(shí)現(xiàn)對(duì)流速與壓強(qiáng)的控制。

由流體力學(xué)原理可知[27],管路內(nèi)徑越小,流體與管路內(nèi)部摩擦越大,其壓力損失將會(huì)增加,為了減小負(fù)壓在管路內(nèi)部的損失,設(shè)計(jì)梯度式管路如圖6b所示,主管路采用內(nèi)徑50 mm的管路,分管路采用內(nèi)徑25 mm的管路,主管路與汽油旋渦風(fēng)機(jī)的負(fù)壓出口相互連接。根據(jù)預(yù)試驗(yàn)結(jié)果可知,單個(gè)排種器最佳吸種負(fù)壓為3.2 kPa,此時(shí)管路內(nèi)的空氣流速為9.8 m/s。根據(jù)流體力學(xué)理論公式(1)可知[27],單個(gè)排種器的負(fù)壓流量為17.31 m3/h。因此,該機(jī)10行排種器需要總體流量為173.1 m3/h,故所選用汽油旋渦風(fēng)機(jī)滿足流量需求。

(1)

式中為氣流流量,m3/h;為管路的橫截面積,m2;為氣流流速,m/s。

采用水平壓力計(jì)針對(duì)每個(gè)排種器吸種負(fù)壓進(jìn)行測(cè)量,吸種負(fù)壓顯示,當(dāng)汽油旋渦風(fēng)機(jī)在最大功率下工作時(shí),每個(gè)排種器的吸種負(fù)壓均≥4.2 kPa,滿足預(yù)試驗(yàn)最佳吸種負(fù)壓要求。

2.3 傳動(dòng)系統(tǒng)設(shè)計(jì)

播種機(jī)傳動(dòng)系統(tǒng)如圖7所示,為滿足傳動(dòng)需求,采用減速箱、齒輪傳動(dòng)和鏈輪轉(zhuǎn)動(dòng)進(jìn)行傳動(dòng)比轉(zhuǎn)換,以滿足穴距調(diào)整要求。整機(jī)選用的洋馬(VP6D)動(dòng)力底盤原插秧株距調(diào)節(jié)范圍為100~220 mm,滿足雜交稻種植穴距范圍要求。動(dòng)力底盤自帶的株距調(diào)節(jié)系統(tǒng)是一組齒輪變速箱,當(dāng)傳動(dòng)比一定,在同一株距下,直播機(jī)前進(jìn)速度與輸出軸轉(zhuǎn)速成正比,其傳動(dòng)系統(tǒng)減速比計(jì)算如公式(2)所示[28]。

式中為動(dòng)力輸出軸與排種軸的傳動(dòng)比,為直播機(jī)動(dòng)力底盤前進(jìn)速度,m/s;為直播機(jī)水田滑轉(zhuǎn)率,%;為PTO轉(zhuǎn)速,r/min;為排種器吸種盤吸孔組數(shù);為穴距,m。

圖6 負(fù)壓系統(tǒng)

由文獻(xiàn)[28]可知,直播機(jī)水田滑轉(zhuǎn)率為15%,當(dāng)PTO轉(zhuǎn)速=608 r/min,穴距= 0.1 m,排種器吸種盤吸孔組數(shù)=12,由公式(2)可知,此時(shí),動(dòng)力輸出軸與排種軸的傳動(dòng)比約為=1∶12。為滿足上述轉(zhuǎn)動(dòng)比需求,采用多級(jí)減速的方式對(duì)傳統(tǒng)系統(tǒng)進(jìn)行設(shè)計(jì),傳動(dòng)系統(tǒng)如圖7所示,其減速箱的減速比為1∶2,且該減速箱采用錐齒輪結(jié)構(gòu)可將PTO的轉(zhuǎn)向變位橫向,與排種軸相互平行,采用1對(duì)1∶2直齒輪再次進(jìn)行減速,并改變轉(zhuǎn)動(dòng)方法,最終采用1∶3鏈輪轉(zhuǎn)動(dòng),將動(dòng)力傳輸?shù)脚欧N軸上,通過(guò)以上3級(jí)傳動(dòng),使動(dòng)力輸出軸與排種軸的傳動(dòng)比傳動(dòng)比達(dá)到1∶12,滿足設(shè)計(jì)要求。

1.動(dòng)力輸出軸PTO 2.減速箱(傳動(dòng)比1∶2) 3.齒輪傳動(dòng)(傳動(dòng)比1∶2) 4.鏈傳動(dòng)(傳動(dòng)比1∶3) 5.聯(lián)軸器 6.排種器

3 田間試驗(yàn)

3.1 試驗(yàn)材料

選取雜交稻甬優(yōu)4949為試驗(yàn)材料,對(duì)該機(jī)田間播種精度進(jìn)行試驗(yàn)驗(yàn)證。試驗(yàn)前稻種在水中浸泡24 h,去除雜質(zhì)與秕谷,對(duì)稻種進(jìn)行催芽處理至破胸露白,此時(shí)芽長(zhǎng)為1~3 mm,由于芽長(zhǎng)較短,在播種過(guò)程中不易被折斷,不會(huì)對(duì)稻種造成損傷。試驗(yàn)前將稻種晾干,測(cè)得稻種平均含水率為23.5%。

試驗(yàn)地點(diǎn)為華中農(nóng)業(yè)大學(xué)試驗(yàn)田,播種前用旋耕機(jī)將田帶水旋耕至起漿,再用平地機(jī)對(duì)水田進(jìn)行平整,沉淀2 d后進(jìn)行播種。此時(shí)土壤表面無(wú)明顯積水,該狀態(tài)下的土壤具有較好的粘附性,直播機(jī)開(kāi)溝效果較好,播種后種子易被土壤粘附,無(wú)彈跳,成穴效果較好。試驗(yàn)時(shí)間為2020年5月20號(hào),環(huán)境溫度為26 ℃。

3.2 試驗(yàn)方法

氣吸式排種器主要通過(guò)負(fù)壓氣流作用將稻種由種群中分離,同時(shí)負(fù)壓是維持稻種始終被吸附于吸種盤上的主要?jiǎng)恿?,是氣吸式排種器工作的必要因素,負(fù)壓的增加將提升吸孔吸附稻種的能力,因此,負(fù)壓對(duì)排種器吸附精度產(chǎn)生影響。由公式(2)可知,當(dāng)轉(zhuǎn)動(dòng)比一定時(shí),直播機(jī)PTO轉(zhuǎn)速與前進(jìn)速度成正相關(guān),同時(shí)PTO與排種軸通過(guò)傳動(dòng)系統(tǒng)相連,因此,直播機(jī)前進(jìn)速度與排種軸轉(zhuǎn)速成正相關(guān)關(guān)系。當(dāng)前進(jìn)速度提升時(shí),排種軸轉(zhuǎn)速提升,轉(zhuǎn)速的提升將增加被吸附稻種的離心力,對(duì)稻種的吸附效果產(chǎn)生影響。因此,本研究選擇吸種負(fù)壓與前進(jìn)速度為試驗(yàn)因素。

參考預(yù)試驗(yàn)結(jié)果可知,當(dāng)吸種負(fù)壓高于4.0 kPa或低于1.6 kPa時(shí),播種合格率較低,不滿足播種作業(yè)要求。由于田間播種試驗(yàn)環(huán)境復(fù)雜,根據(jù)預(yù)試驗(yàn)結(jié)果,取吸種負(fù)壓為2.4、3.2和4.0 kPa。采用水平壓力計(jì)對(duì)吸種負(fù)壓進(jìn)行測(cè)量[7],由于管路內(nèi)部氣壓分布存在差異,管路2端氣壓小于中間氣壓,選取一端排種器為測(cè)量點(diǎn),檢測(cè)該排種器的負(fù)壓,當(dāng)該排種器滿足最佳吸種負(fù)壓條件時(shí),中間排種器的吸種負(fù)壓將高于該排種器,中間排種器的播種量將高于2端,可減小排種器的總體漏播率。由于水田土壤泥濘,水稻直播機(jī)行走阻力較大,當(dāng)前進(jìn)速度達(dá)1 m/s時(shí),即視為高速作業(yè)[24]。同時(shí)由于水田泥腳深淺不一,導(dǎo)致直播機(jī)田間作業(yè)時(shí)難以保證始終勻速前進(jìn),因此,試驗(yàn)時(shí)盡可能控制直播機(jī)田間前進(jìn)速度均勻,通過(guò)前期田間標(biāo)定試驗(yàn),當(dāng)直播機(jī)低速行駛時(shí),其前進(jìn)速度為0.2~0.4 m/s,中速為0.5~0.7 m/s,高速為0.8~1.0 m/s。選取低、中、高3個(gè)試驗(yàn)水平的作業(yè)速度,如表 3所示。田間試驗(yàn)與田間出苗長(zhǎng)勢(shì)和作業(yè)效果如圖8所示。

表3 試驗(yàn)因素水平表

3.3 評(píng)價(jià)指標(biāo)

參考GB-T 6973—2005[29]確定雙腔氣力式水稻精量直播機(jī)田間播種性能檢測(cè)指標(biāo)與方法。連續(xù)記錄直播機(jī)每穴排出種子的數(shù)量。由于該直播機(jī)具有10個(gè)排種器,將直播機(jī)上的排種器從左至右依次編號(hào)為1~10,記錄每一個(gè)排種器的每穴播種精度X,每個(gè)排種器各取100穴,重復(fù)3次(即每個(gè)排種器取300穴),計(jì)算公式如式(3)。以3~5粒/穴為合格指標(biāo),0~2粒/穴為漏播指標(biāo),大于5粒/穴為重播指標(biāo)。采用SPSS軟件[30]對(duì)統(tǒng)計(jì)后的數(shù)據(jù)進(jìn)行處理。

式中p(i)為各指標(biāo)占比;Xi為滿足各指標(biāo)的總穴數(shù)。

4 結(jié)果與分析

田間試驗(yàn)結(jié)果如圖9~11所示,10行平均數(shù)與變異系數(shù)如表4所示。

由圖9可知,當(dāng)直播機(jī)低速作業(yè)時(shí),吸種負(fù)壓提升至4.0 kPa,大于5粒/穴占比會(huì)大幅度提高,約提升了60%,當(dāng)直播機(jī)中速與高速作業(yè)時(shí),吸種負(fù)壓提升至4.0 kPa時(shí),其大于5粒/穴占比提升了約20%,低速運(yùn)轉(zhuǎn)時(shí),大于5粒/穴占比遠(yuǎn)高于中速與高速,播種合格率大幅度降低。主要原因?yàn)椋寒?dāng)直播機(jī)低速播種時(shí),由于排種盤轉(zhuǎn)速與直播機(jī)前進(jìn)速度相互匹配,所以排種盤轉(zhuǎn)速較低,當(dāng)排種盤低速運(yùn)轉(zhuǎn),吸孔與經(jīng)過(guò)吸種區(qū)的時(shí)間增加,吸孔接觸稻種的時(shí)間也增加,同時(shí),由于負(fù)壓提升至4.0 kPa,吸孔吸附稻種的吸力也隨之提升,因此,大于5粒/穴占比增加。此外,排種盤轉(zhuǎn)速較低,稻種被吸附后所受的離心力減小,稻種不會(huì)因?yàn)槲Σ蛔愣撾x吸種盤。以上原因?qū)е铝水?dāng)直播機(jī)低速前進(jìn)、吸種負(fù)壓為4.0 kPa時(shí),大于5粒/穴占比大幅度增加,以上2個(gè)因素都會(huì)增加吸孔對(duì)稻種的吸附概率,提高大于5粒/穴占比,這與現(xiàn)有研究結(jié)果一致[31-32]。

由圖9和圖10可知,當(dāng)吸種負(fù)壓為2.4與3.2 kPa時(shí),播種合格率隨直播機(jī)前進(jìn)速度的增加而減小,主要原因?yàn)椋寒?dāng)吸種負(fù)壓為2.4與3.2 kPa時(shí),吸力不足,此時(shí)增加吸種盤轉(zhuǎn)速會(huì)增加離心力等不穩(wěn)定因素,從而導(dǎo)致吸種穩(wěn)定性降低,0~2粒/穴占比增加。因此,播種合格率隨直播機(jī)前進(jìn)速度的增加而減小。

圖9 直播機(jī)低速(0.2~0.4 m·s-1)作業(yè)試驗(yàn)結(jié)果

圖10 直播機(jī)中速(0.5~0.7 m·s-1)作業(yè)試驗(yàn)結(jié)果

由圖9~11可知,10個(gè)排種器之間的播種效果存在一定的波動(dòng)。中間位置排種器的大于5粒/穴占比要略高于兩端排種器,0~2粒/穴占比要略低于兩端的排種器。產(chǎn)生該現(xiàn)象的主要原為,排種器負(fù)壓由旋渦氣泵提供,旋渦氣泵產(chǎn)生吸種負(fù)壓,經(jīng)由負(fù)壓管路分配至各個(gè)排種器,本文采用分支式管路,隨著管路長(zhǎng)度的增加與管路的折彎拐角增多引起氣壓損失增加,因此兩端分管路的氣壓損失高于中間管路,故其吸種負(fù)壓小于中間管路,導(dǎo)致了中間排種器的大于5粒/穴占比高,0~2粒/穴占比低。

由表4試驗(yàn)結(jié)果可知,當(dāng)吸種負(fù)壓為3.2 kPa時(shí),播種合格率(3~5粒/穴占比)高于4.0與2.4 kPa的合格率,低速時(shí)其平均播種合格率為91.04%,大于5粒/穴占比6.73%。

由表4試驗(yàn)結(jié)果可知,當(dāng)直播機(jī)低速播種時(shí),排種器的各行平均播種粒數(shù)分別為4.02、4.16和4.99,中速時(shí)平均播種粒數(shù)分別為:3.78、4.02和4.75,高速時(shí)平均播種粒數(shù)分別為:3.13、3.77和4.58。由平均播種粒數(shù)試驗(yàn)結(jié)果可知,平均播種粒數(shù)隨吸種負(fù)壓的增加而增加,隨直播機(jī)前進(jìn)速度的減小而增加。當(dāng)吸種負(fù)壓為4.0 kPa時(shí),平均播種粒數(shù)均大于4.5粒/穴。

圖11 直播機(jī)高速(0.8~1.0 m/s)作業(yè)試驗(yàn)結(jié)果

表4 不同作業(yè)速度下各行排種器變異系數(shù)分析

注:# 為無(wú)變異。由于低速作業(yè)時(shí),0~2?!ぱ?1占比為0,因此無(wú)變異。

Note: # is no variation. When the seeder worked at low speed, the probability of 0-2 seeds·hill-1was 0, so there was no variation.

由圖8可知,該裝置的田間播種均勻性較好,田間出苗效果良好,行距穴距基本均勻,其播種精度與種植密度滿足水稻水田農(nóng)藝種植要求。由表4可知,田間作業(yè)時(shí),10行播種合格率和播種平均數(shù)的變異系數(shù)均小于5%,其中,當(dāng)吸種負(fù)壓為3.2 kPa時(shí),播種合格率變異系數(shù)均小于2%??梢?jiàn)因管路差異造成的氣壓波動(dòng)對(duì)播種合格率影響較小,滿足田間均勻播種的要求。

5 討 論

由田間試驗(yàn)結(jié)果可知,當(dāng)直播機(jī)低速作業(yè)時(shí),吸種負(fù)壓為3.2 kPa時(shí),10行排種器平均播種合格率最高為91.04%,空穴率為0,與原有的單腔單吸種盤直播機(jī)相比[31],該直播機(jī)空穴率降低了2%左右。

分析其減少空穴的機(jī)理如下:該直播機(jī)采用雙腔雙吸種排種器對(duì)稻種進(jìn)行吸附,前人研究顯示[33],氣力式排種器各吸孔對(duì)稻種的吸附過(guò)程受稻種品種、狀態(tài)、排種器結(jié)構(gòu)與運(yùn)動(dòng)參數(shù)等多種因素影響,常規(guī)單腔氣力式排種器單側(cè)吸種會(huì)由于未吸附稻種或稻種提前脫落、未在投種區(qū)投放等原因產(chǎn)生空穴,而雙側(cè)吸種因具有兩個(gè)吸種盤,其吸種過(guò)程相互獨(dú)立,兩側(cè)吸盤同時(shí)吸附不了稻種的概率會(huì)相應(yīng)大大下降。因此,本機(jī)田間播種空穴率得到顯著改善。

6 結(jié) 論

1)針對(duì)雜交稻水田直播均勻精量直播要求,本文設(shè)計(jì)了一種雙腔氣力式水稻精量直播機(jī),介紹了直播機(jī)的工作原理,對(duì)其主要工作部件進(jìn)行分析。

2)以雜交稻甬優(yōu)4949為試驗(yàn)對(duì)象,在不同吸種負(fù)壓與不同直播機(jī)前進(jìn)速度條件下進(jìn)行了田間試驗(yàn)。試驗(yàn)結(jié)果表明:當(dāng)吸種負(fù)壓為3.2 kPa、直播機(jī)低速作業(yè)時(shí),播種效果最佳,10行排種器平均播種合格率(3~5粒/穴率)為91.04%,0~2粒/穴占比為2.23%,大于5粒/穴占比為6.73%,各排種器之間的播種合格率變異系數(shù)均小于5%,滿足雜交稻水田均勻精量播種要求。

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Development and experiment of double cavity pneumatic rice precision direct seeder

Xing He, Zhang Guozhong※, Han Yuhang, Gao Yuan, Zha Xiantao

(1.,,430070,,,,430070,)

Rice is one of the main food crops for more than 50% of the world's population. Mechanized rice direct seeding was roughly divided into broadcast seeding, drilling and hill seeding. The broadcast seeding was not conducive to the field growth and management, where the seeding precision was low, the distribution of rice seeds was irregular in the field, and the uniformity of seedling emergence was not good. In the drill seeding, the field distribution was better regular than that in the broadcast seeding. Since about 50% of rice planting area in China is hybrid rice at present, the drill seeding cannot meet the requirements of hybrid rice seeding, particularly suitable for the conventional rice because of its large seeding rate. The hybrid rice has stronger tillering ability and higher yield, compared with the conventional rice. Furthermore, only 3-5 seeds/hill is needed to form high-yield structure, when the mechanized direct seeding was adopted. In this study, a double-cavity pneumatic precision direct seeder was designed for the hybrid rice, with the seeding rate of 3-5 seeds/hill as the goal, thereby to meet the requirement of hybrid rice direct seeding in the field. The seeder was mainly composed of a double-cavity pneumatic seed metering device, gasoline vortex pump, negative pressure pipeline, ditching equipment, and transmission system, where the seed metering device was introduced, and the transmission system was designed. The vacuum pump was also selected, where the gradient reducing pipeline was designed to provide the air flow of negative pressure, according to the negative pressure of seed metering device. Taking the hybrid rice Yongyou 4949 as experimental materials, a field test was carried out under the various negative pressure of sucking seed, and forward speed of seeder (i.e., the rotation speed of sucking seed plate). An attempt was made to explore the effects of sucking seed negative pressure and the forward speed on seeding precision of double-cavity pneumatic rice precision direct seeder. As such, a new type of pneumatic direct seeder was designed with a double cavity for rice precision seeding, according to the requirement of direct seeding of hybrid rice in the field. A field experiment was also carried out to obtain the best working parameters, after the design for the main working parts of the seeder. The results showed that the average seeding qualified rate (3-5 seeds/hill rate) of seeder was 91.04%, the probability of 0-2 seeds/hill was 2.23%, the probability more than 5 seeds/hill was 6.73%, the average number of seeding was 4.16, and the variation coefficient of seeding qualified was 1.24%, when the negative pressure of sucking seed was 3.2 kPa and the forward speed of seeder was low (0.2-0.4 m/s). Two factors can be contributed to the values of parameters in field tests lower than those in laboratory tests. The uneven mud surface can determine the field work of seeder, due to the complex environment of field seeding can be detrimental to the performance of seed sucking, particularly on the vibration of seeder. In the uneven distribution of negative pressure, there was a significant influence on the seeding precision of seeds metering devices, where the others would not be able to achieve the optimal negative pressure of seed sucking, when some of seed-metering devices reached. In the field test, the probability of 0 seed/hill was 0. Compared with the original seeder with the single cavity and single sucking plate, the pneumatic rice precision direct seeder with the double cavity can effectively improve the probability of 0 seed/hill. The seeding precision can meet the requirement of direct seeding of hybrid rice in the field. The finding can provide a sound reference for the precision direct seeding and equipment of hybrid rice.

agricultural machinery; design; seeder; pneumatic; hybrid rice; double cavity; precision seeding

邢赫,張國(guó)忠,韓宇航,等. 雙腔氣力式水稻精量水田直播機(jī)設(shè)計(jì)與試驗(yàn)[J]. 農(nóng)業(yè)工程學(xué)報(bào),2020,36(24):29-37.doi:10.11975/j.issn.1002-6819.2020.24.004 http://www.tcsae.org

Xing He, Zhang Guozhong, Han Yuhang, et al. Development and experiment of double cavity pneumatic rice precision direct seeder[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2020, 36(24): 29-37. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2020.24.004 http://www.tcsae.org

2020-07-16

2020-11-04

國(guó)家重點(diǎn)研發(fā)計(jì)劃子課題(2017YFD0301404-05,2018YFD0301304-3);中央高?;究蒲袠I(yè)務(wù)費(fèi)專項(xiàng)基金(2662018PY038);湖北省高等學(xué)校優(yōu)秀中青年科技創(chuàng)新團(tuán)隊(duì)計(jì)劃項(xiàng)目(T201934)

邢赫,博士后,研究方向?yàn)樗旧a(chǎn)機(jī)械化技術(shù)與裝備。Email:hexing@mail.hzau.edu.cn

張國(guó)忠,教授,博士,研究方向?yàn)樗旧a(chǎn)機(jī)械化技術(shù)與裝備。Email:zhanggz@mail.hzau.edu.cn

10.11975/j.issn.1002-6819.2020.24.004

S233.71

A

1002-6819(2020)-24-0029-09

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