KQYJ-1T 空氣壓機設(shè)計【說明書+CAD+SOLIDWORKS】
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空氣壓機設(shè)計
前言
時間轉(zhuǎn)瞬即逝，轉(zhuǎn)眼之間四年的大學(xué)生涯就要結(jié)束了，回首四年的學(xué)習(xí)生活，我感到自己的收獲無比豐富。四年來，我不僅認真學(xué)習(xí)了各門基礎(chǔ)課，而且更加系統(tǒng)地掌握了多門專業(yè)技術(shù)課，在每次的課程設(shè)計中，我都認真對待，努力鉆研。這樣，通過四年的鍛煉不斷地提高了我的設(shè)計、繪圖、識圖能力?？梢哉f，大學(xué)里的理論基礎(chǔ)，不但使我學(xué)會了分析問題、解決問題的能力，而且更強化了我的知識結(jié)構(gòu)。尤其幸運的是，我不只一次地深入工廠實習(xí)，把學(xué)到的知識應(yīng)用于實習(xí)現(xiàn)場的具體工作中，提高了自己的動手能力，為我今后步入工作崗位打下了更好的實踐基礎(chǔ)。
本次設(shè)計的目的培養(yǎng)學(xué)生初步掌握獨立從事專業(yè)技術(shù)工作的能力，提高學(xué)生從事工藝和工藝裝備設(shè)計的水平，使學(xué)生初步掌握從事本專業(yè)科學(xué)研究工作的能力。通過畢業(yè)設(shè)計不但培養(yǎng)了我們運用各種工具書的方法和技巧，同時也培養(yǎng)了我們獨立思考問題、解決問題的能力。通過翻閱查找各種工具書，擴大了視眼，豐富了自己的知識范圍。
本次設(shè)計我們是有充分準(zhǔn)備的。我們不僅準(zhǔn)備了四年的時間來掌握各門專業(yè)課學(xué)習(xí)，而且我們多次深入工廠實習(xí)，更主要的是設(shè)計期間不斷地從網(wǎng)上、圖書館收集大量的資料，尋找各種解決問題的方法。所以說本設(shè)計我們是有充分準(zhǔn)備的，它是與生產(chǎn)實際相結(jié)合。它也將成為我們走上工作崗位的一次重要演習(xí)，為我們今后的工作打下堅實的基礎(chǔ)。
第一章 電控氣動壓力機方案設(shè)計
1.1 設(shè)計任務(wù)抽象化
設(shè)計要求：所設(shè)計的設(shè)備要求完成自動送料出入至施壓點、給予和清刷沖頭等功能。并要求每次給定的壓力在一定的范圍內(nèi)，保證效率在每分鐘6~20次，工作壓力不小于0.6Mpa，能量220V交流電。
1.1.1建立黑箱
1.1.2功能分解
1.2確定工藝原理
確定依據(jù)：成本、質(zhì)量、效率三者綜合比較。
功 能
1. 實現(xiàn)對料粉一定壓力壓實。
2.工作頻率沒分鐘6~20次。
必要要求必要要求
加工
4.小批生產(chǎn)，中小型廠加工
基本要求
成本
5. 成本不高
6.結(jié)構(gòu)簡單
附加要求
附加要求
使用
7.操作方便
附加要求
1.3確定技術(shù)過程
1.4引進技術(shù)系統(tǒng)，確定邊界
1.5確定功能結(jié)構(gòu)
1.5.1 技術(shù)系統(tǒng)總功能，及進行功能分解
空氣壓機（KQYJ-1T）電控氣動壓力機的動力源為壓縮空氣，它是通過使用倍力氣缸和配重塊來完成對殼體內(nèi)的壓料進行壓實，由于作用在殼體藥劑內(nèi)的力是一對相互作用力，因此在配重塊不變的情況下每次壓裝時殼體內(nèi)藥劑受到的作用力是一致的。工作過程：將裝有需要壓裝的產(chǎn)品模子放入送?；迳系哪＞叩鬃鶅?nèi)，按下啟動按鈕后延時t秒（可調(diào)），送模氣缸動作將模子送到工作位置，同時模子進出門洞關(guān)起，倍力氣缸控制閥工作，活塞桿推動托模上移塊將到位的模座和模子向上推起，壓藥沖通過脫模導(dǎo)沖板和導(dǎo)沖模進入產(chǎn)品殼體內(nèi)壓實藥劑，在壓力增加的過程中，壓藥沖將作用力傳給壓頭和配重塊支架并將起頂起上移，當(dāng)支架托塊上移到脫離接近開關(guān)的感應(yīng)時，倍力氣缸進氣口停止進氣，保壓一定時間后倍力氣缸反向進氣，托模上移塊下移回位，送?；鍎幼鲗⒛Ｗ湍Ｗ右黄鹚统龌氐狡鹗嘉?，在將模子從模座中取出前，送模滑板一直保持起始狀態(tài)，只有當(dāng)從模座內(nèi)取出模子并再次放入產(chǎn)品后，下一個工作循環(huán)才能進行。
當(dāng)倍力氣缸活塞桿回到位后，清刷計數(shù)到后，清刷缸開始對沖子清刷，清刷的次數(shù)由文本上設(shè)置而定，只有當(dāng)清刷完后，才可以進入下一個產(chǎn)品的。在清刷過程中如有異?？砂聪录蓖ｉ_關(guān)停止清刷。
第二章 倍力氣缸設(shè)計
2.1 工作動力類型的選擇
經(jīng)查閱資料和市場考察，決定使用氣動氣缸為工作動力。
氣動技術(shù)有以下優(yōu)點:
(1)介質(zhì)提取和處理方便。氣壓傳動工作壓力較低，工作介質(zhì)提取容易，而后排入大氣，處理方便，一般不需設(shè)置回收管道和容器:介質(zhì)清潔，管道不易堵存在介質(zhì)變質(zhì)及補充的問題.
(2)阻力損失和泄漏較小，在壓縮空氣的輸送過程中，阻力損失較小(一般不卜澆塞僅為油路的千分之一)，空氣便于集中供應(yīng)和遠距離輸送。外泄漏不會像液壓傳動那樣，造成壓力明顯降低和嚴(yán)重污染。
(3)動作迅速，反應(yīng)靈敏。氣動系統(tǒng)一般只需要0.02s-0.3s即可建立起所需的壓力和速度。氣動系統(tǒng)也能實現(xiàn)過載保護，便于自動控制。
(4)能源可儲存。壓縮空氣可存貯在儲氣罐中，因此，發(fā)生突然斷電等情況時，機器及其工藝流程不致突然中斷。
(5)工作環(huán)境適應(yīng)性好。在易燃、易爆、多塵埃、強磁、強輻射、振動等惡劣環(huán)境中，氣壓傳動與控制系統(tǒng)比機械、電器及液壓系統(tǒng)優(yōu)越，而且不會因溫度變化影響傳動及控制性能。
(6)成本低廉。由于氣動系統(tǒng)工作壓力較低，因此降低了氣動元、輔件的材質(zhì)和加工精度要求，制造容易，成本較低。
2.2 氣缸及其附件的設(shè)計
倍力氣缸由：前端蓋，活塞，活塞桿、連接法蘭、后端蓋缸筒和密封件組成。
因為工作要求的壓力不大于1噸（即為100MPa），且按常見的現(xiàn)場工作壓力為0.5MPa。
2.2.1 氣缸的設(shè)計和計算
（1） 根據(jù)工作機構(gòu)運動要求和結(jié)構(gòu)要求，參考《機械設(shè)計手冊 5》表38.2-1選擇組合氣缸中的增壓氣缸；參考表38.2-2選擇氣缸為前法蘭MF1式的連接方式。
活塞面積×工作氣壓力=活塞推力
要求工作壓力不大于100MPa，計算則取極限值100MPa。經(jīng)計算得到活塞面積S。同時要考慮到缸筒的內(nèi)徑選擇，查閱《機械設(shè)計手冊 5》表38.2-4，分別選擇內(nèi)徑為125mm和100mm的作為缸筒外徑。
氣缸加工要求：氣缸兩端必須倒角，以利于缸蓋裝配。
為了防腐和提高壽命，缸內(nèi)鍍鉻，在拋光，鉻層厚度為0.01~0.03mm。
外表面涂漆。
（2）氣缸壁厚計算
結(jié)合計算結(jié)構(gòu)并參考《機械設(shè)計手冊 5》表38.2-7，最后確定壁厚為4mm。
（3）活塞桿的計算
并查閱《機械設(shè)計手冊 5》最終確定活塞桿的各部分直徑大小。
為了便于加工和裝配，最終確定活塞外徑為123mm和98mm。單邊留有1mm余量，便于密封件的裝配。并且用螺母將活塞桿和或是固定。
設(shè)定氣缸的工作行程為140mm，加上活塞的厚度和余量，每個缸筒長度定位225mm。
（5）連接 1.端蓋和缸筒連接采用雙頭螺栓連接，并用O型密封圈密封。
2.活塞桿和活塞用緊固螺母固定。
（6）密封，活塞桿用O型密封圈，活塞上用對裝的Y型密封圈，并在中間在導(dǎo)向帶。
（7） 外聯(lián)螺桿，端蓋，和法蘭均經(jīng)行氧化發(fā)黑處理，防止生銹。
第三章 自動送料機構(gòu)設(shè)計
由于工作壓力在對操作者可能會存一些隱含的危險，因此設(shè)計送料機構(gòu)為氣缸輸送，并在設(shè)壓區(qū)加防護用鋼罩和防彈玻璃。且選用導(dǎo)軌和滑板在輸送系統(tǒng)中，節(jié)省空間且加潤滑油后摩擦阻力更小。
3.1送料滑板設(shè)計
為了更好的起到定位，并使滑板在滑軌上的運動更平穩(wěn)，選擇了在滑板兩側(cè)開內(nèi)凹滑槽，并在加工凹槽時保證其平行度，各接觸邊多角。為了防止材料生銹，滑板表面進行電鍍使其生成一層致密的氧化膜。
滑軌則根據(jù)滑板的要求進行配加工，并且也要進行電鍍處理，成對加工，保證其平行度。。
3.2 定位、脫模調(diào)節(jié)設(shè)計
為了方便放料和在工作施壓結(jié)束后，根據(jù)所需產(chǎn)品在滑板上設(shè)置了限位槽（圖3.1）。
參考產(chǎn)品外殼尺寸留有一定余量確定限位槽尺寸。
圖 3.1
送料滑板將料殼送入后，須正對施壓的沖頭，才能保證工作壓力的恒定和工作的安全、平穩(wěn)進行。
設(shè)計了定位零件，其定位根據(jù)沖頭的位置來定。并且其上對不同高度料殼的拔模開有長腰槽（圖3.2），可以進行調(diào)節(jié)高度，并配有兩個不同尺寸的脫模調(diào)節(jié)塊。
圖 3.2
所有送料機構(gòu)都采用材料Q235A，并電鍍進行保護處理。
3.3 送料裝置氣缸的選擇
根據(jù)設(shè)備工作要求行程，留余量取整，選擇行程為了200mm缸。查閱《亞德客集團氣缸購買手冊》。選擇了38mm內(nèi)徑（最小內(nèi)徑）SC型氣缸，SC為標(biāo)準(zhǔn)缸，有利于節(jié)約成本。參考為設(shè)備平放氣缸，固定方式選LB式。則送料裝置氣缸的型號確定為：SC-32×200-LB。
為氣缸設(shè)計一支撐座如圖 3.3.
第四章 清擦機構(gòu)的設(shè)計
4.1清擦機構(gòu)設(shè)計方案分析
由于工作所對的壓料為粉狀，經(jīng)過數(shù)次施壓工作后，會有壓料沾在沖頭上，累積沖頭上將為影響到設(shè)備的正常工作。因此設(shè)計套沖頭清擦機構(gòu)，并和PLC系統(tǒng)和氣缸驅(qū)動相結(jié)合，是機構(gòu)安全簡單，并設(shè)定好數(shù)據(jù)后可以自動運行。
由于清刷缸的動作是由文本上的清刷計數(shù)、清刷次數(shù)來控制的。當(dāng)倍力氣缸活塞桿回到位后，清刷計數(shù)到后，清刷缸開始對沖子清刷，清刷的次數(shù)由文本上設(shè)置而定，只有當(dāng)清刷完后，才可以進入下一個產(chǎn)品的。在清刷過程中如有異常可按下急停開關(guān)停止清刷。
4.2 清擦機構(gòu)機構(gòu)的確定
4.2.1. 和送料機構(gòu)一樣，動力選擇的是氣缸運動來完成，所以同樣也采用滑軌裝置，并且選擇內(nèi)嵌式的燕尾槽。
并采用螺釘固定在機座臺面板上?；壱M行氧化發(fā)黑保護處理
4.2.2. 用于沖頭是垂直水平方向安裝，而清擦氣缸是水平放置，因此要清擦沖頭，需要設(shè)計一個機構(gòu)轉(zhuǎn)換力的方向。查閱資料決定選用在滑塊上帶齒條裝置和普通圓柱齒輪來完成。
由于傳動要求不高，因此采用最簡單的圓柱直齒齒輪，查閱《設(shè)計手冊》并計算后得到齒輪數(shù)據(jù)如下：
齒數(shù)： Z=18
壓力角：α=20°
模數(shù)： m=1.5
齒頂高：ha=1.5
齒根高：hf=1.875
全齒高：h=3.375
齒條底部根據(jù)所選用燕尾槽尺寸進行配加工。
齒條上參數(shù)如下：
齒數(shù)： Z=40
壓力角：α=20°
模數(shù)： m=1.5
齒頂高：ha=1.5
齒根高：hf=1.875
全齒高：h=3.375
齒距：P=4.712
4.2.3. 其它零件：
螺桿采用45號鋼材，并附螺紋。表面氧化發(fā)黑處理。
螺母和擦沖板配合并和螺桿嚙合，使得在氣缸運動帶動齒條移動，使齒輪轉(zhuǎn)動，因為齒輪通過華建和螺桿連接，轉(zhuǎn)動傳至螺桿，在定好螺桿螺紋后，則運動會使沖擦板勻速在縱向運動從而達到清擦沖頭的目的。
在沖擦板的另一頭，卡位在定位擋桿上。其定位和導(dǎo)向作用。
其轉(zhuǎn)配關(guān)系如下。
4.氣缸也采用同樣的支承座，氣缸通過計算采用型號：SC-32×160-LB.
第五章 機座部分
機座部分包括：配重塊支架、壓頭滑套、?？蚣?、觀察窗、臺面板、底板、氣缸安裝板、機座、導(dǎo)柱。
5.1 配重塊
配重塊是用來按照不同要求添加支撐塊其上，以到達不同壓力的裝置。其由22mm厚的鋼板和直徑為76mm的鋼柱焊接成。并和滑套連接配合不同要求的施壓沖頭以完成。
5.2 安全措施
由于設(shè)備工作的壓力盒壓料的特殊性，特加防彈玻璃，提高操作者的安全度。
5.3 臺面板
臺面板 起到安裝?？蚣?、底板、氣缸安裝板、機座的重要作用。
5.4 機架
由設(shè)計要求的外型尺寸：
外形尺寸：（長×寬×高）不大于（1000mm×700mm×1750mm）確定機架的尺寸。
機架采用厚度為5mm的63槽鋼。
5.5 其余材料
其余所有材料均采用Q235A。其中配重塊支架、壓頭滑套、?？蚣?、觀察窗、臺面板、底板、氣缸安裝板經(jīng)行氧化發(fā)黑處理，導(dǎo)柱電鍍拋光。
5.6 配重塊
配重塊，分為20kg、10kg、5kg、2kg、1kg五種。
第六章 電路、氣路控制
本設(shè)備電路、氣路控制主要由PLC控制系統(tǒng)來完成。
PLC叫可編程控制器，是一種帶有指令存儲器，數(shù)字或模擬輸入/輸出接口，以位運算為主，能夠完成邏輯，順序，定時，記數(shù)和算術(shù)運算等功能，用于控制機器或生產(chǎn)過程的自動控制裝置。
PLC控制系統(tǒng)有以下優(yōu)點：
1 數(shù)字運算操作的電子系統(tǒng)——也是一種計算機
2 專為在工業(yè)環(huán)境下應(yīng)用而設(shè)計
3 面向用戶指令——編程方便
4 邏輯運算、順序控制、定時計算和算術(shù)操作
5 數(shù)字量或模擬量輸入輸出控制
6 易與控制系統(tǒng)聯(lián)成一體
7 易于擴充
且PLC因為是模塊式的，所以擴展容易，邏輯控制優(yōu)勢明顯，布線簡單，監(jiān)控方便，編程容易上手，開發(fā)周期短，快捷方便，這是其優(yōu)點。
電路、氣路控制圖如下：
結(jié)合電氣控制系統(tǒng)詳細工作原理如下：
HQYJ-1T電控氣動壓力機的動力源為壓縮空氣，它是通過使用倍力氣缸和配重塊來完成對殼體內(nèi)的藥劑進行壓實，由于作用在殼體藥劑內(nèi)的力是一對相互作用力，因此在配重塊不變的情況下每次壓裝時殼體內(nèi)藥劑受到的作用力是一致的。工作過程：將裝有需要壓裝的產(chǎn)品模子放入送?；迳系哪＞叩鬃鶅?nèi)，按下啟動按鈕后延時t秒（可調(diào)），送模氣缸動作將模子送到工作位置，同時模子進出門洞關(guān)起，倍力氣缸控制閥工作，活塞桿推動托模上移塊將到位的模座和模子向上推起，壓藥沖通過脫模導(dǎo)沖板和導(dǎo)沖模進入產(chǎn)品殼體內(nèi)壓實藥劑，在壓力增加的過程中，壓藥沖將作用力傳給壓頭和配重塊支架并將起頂起上移，當(dāng)支架托塊上移到脫離接近開關(guān)的感應(yīng)時，倍力氣缸進氣口停止進氣，保壓一定時間后倍力氣缸反向進氣，托模上移塊下移回位，送?；鍎幼鲗⒛Ｗ湍Ｗ右黄鹚统龌氐狡鹗嘉唬趯⒛Ｗ訌哪Ｗ腥〕銮?，送?；逡恢北３制鹗紶顟B(tài)，只有當(dāng)從模座內(nèi)取出模子并再次放入產(chǎn)品后，下一個工作循環(huán)才能進行。
6.1 模子送進
模子放入模座，光點傳感器感應(yīng)觸發(fā)后延時t秒（可調(diào)），PLC接到信號后接通DY3電磁閥電源，DY3通電時換向，送模氣缸進出氣換向，將送模滑板及防護門拉送到位。
6.2 工作過程
在送模氣缸將送模滑板及防護門拉送到位的同時，氣缸上的磁石感應(yīng)開關(guān)接通，PLC接到信號后電磁閥DY1線圈通電，電磁閥換向倍力氣缸活塞桿上移到位對殼體內(nèi)的藥劑進行壓實。
6.3 保壓延時
在倍力氣缸活塞桿上移壓實殼體內(nèi)藥劑的同時，壓頭對配重塊支架施加向上的作用力將其頂起，當(dāng)支架托盤遠離接近傳感器時，PLC接到信號后給電磁閥DY2線圈通電關(guān)閉進氣口，倍力氣缸活塞桿輸出力與配重塊支架重物下壓力平衡，延時t1秒（可調(diào)）后，PLC發(fā)出指令電磁閥DY1線圈斷電電磁閥換向。
6.4 倍力氣缸回位過程
PLC延期到時后，輸出開關(guān)信號讓DY1、 DY2同時斷電，電磁閥換向，倍力氣缸活塞桿回位。
6.5 模子送出
倍力氣缸活塞桿回位時，送模塊導(dǎo)桿同時到位觸發(fā)接近開關(guān)，PLC接到信號后發(fā)出指令切斷DY3電磁閥電源，電磁閥換向，送?；鍘е鴫褐频漠a(chǎn)品送出。只有在取出產(chǎn)品并放入下一個產(chǎn)品后，下一個工作循環(huán)才能進行。
6.6 清刷過程
清刷缸的動作是由文本上的清刷計數(shù)、清刷次數(shù)來控制的。
當(dāng)倍力氣缸活塞桿回到位后，清刷計數(shù)到后，清刷缸開始對沖子清刷，清刷的次數(shù)由文本上設(shè)置而定，只有當(dāng)清刷完后，才可以進入下一個產(chǎn)品的。在清刷過程中如有異?？砂聪录蓖ｉ_關(guān)停止
清刷。
參 考 文 獻
[1]
《機械設(shè)計使用手冊》------機械工業(yè)出版社 主編：王少懷，徐安東，高紅霞
[2]
《新編機械設(shè)計手冊》-------遼寧科學(xué)出版社 主編：蔡春源
[3]
《精通 Solid Works》------夸克工作室 主編：賴育良
[4]
《機械設(shè)計》------武漢理工大學(xué)出版社 主編：楊明忠，朱家誠
[5]
《AUTO CAD 2006中文版》-----大連理工大學(xué)出版社 主編：余桂英
[6]
《機械制造技術(shù)基礎(chǔ)》-----武漢理工大學(xué)出版社 主編：曾志新
[7]
《PRO/ENGINEER Wildfire 3.0》--------清華大學(xué)出版社 主編：卲立新，孫江宏
致 謝
這次畢業(yè)設(shè)計可以圓滿地首先要感謝文建萍老師的大力指導(dǎo)，在問老師細心的指導(dǎo)下不僅完成了本次課程設(shè)計任務(wù)，并且在專業(yè)知識上得到了極大的補充，一定會對我以后的工作起到很大的幫助。然后要感謝學(xué)校四年的栽培，讓我們在進入社會前學(xué)會了專業(yè)技能。最后要感謝工作所在公司的師傅和同事的細心幫助，使我在專業(yè)理論和實踐理論上都獲得了很多的寶貴經(jīng)驗。
- 20 -
江西農(nóng)業(yè)大學(xué)畢業(yè)設(shè)計任務(wù)書
設(shè)計（論文）
課題名稱
KQYJ-1T 空氣壓機設(shè)計
學(xué)生姓名
丁 劍
院（系）
工學(xué)院
專 業(yè)
機械設(shè)計制造及其自動化
指導(dǎo)教師
文建萍
職 稱
講師
學(xué) 歷
本科
畢業(yè)設(shè)計（論文）要求：
1. 設(shè)計要獨立完成，不得抄襲。
2. 設(shè)計要具有一定的實用性。
3. 查閱相關(guān)的文獻、資料，通過查閱文獻、資料擴充知識面。
4. 設(shè)計說明書和圖紙符合國標(biāo)規(guī)定及工學(xué)院的畢業(yè)設(shè)計要求。
5. 完成一份8000字以上的設(shè)計說明書和共計1.5張的AO圖紙。
畢業(yè)設(shè)計（論文）內(nèi)容與技術(shù)參數(shù)：
設(shè)計內(nèi)容：1.氣缸的設(shè)計和選擇。2.傳送機構(gòu)的設(shè)計。3.清擦系統(tǒng)的設(shè)計。4.機架的設(shè)計。5.控制電路的涉及及材料的選用。
技術(shù)參數(shù)：1、外形尺寸：（長×寬×高）不大于（1000mm×700mm×1750mm）。2、最大額定增壓壓力：1T。3、最大額定輸出工作壓力:1000kg。4、托模上移塊上移的總行程：140mm。5、工作效率每分鐘6到20次。6、工作氣源壓力：≤0.6Mpa7、工作電源電壓：220V，0.1kw。
畢業(yè)設(shè)計（論文）工作計劃：
一、課題準(zhǔn)備階段，了解課題課題的內(nèi)容，初步定出解決方案;
二、氣缸的計算和選用。
三、熟悉AutoCAD繪圖及 機械設(shè)計，材料力學(xué)等相關(guān)知識；
四、出AutoCAD二維圖紙，然后出SolidWorks三維圖。
五 、 撰寫畢業(yè)論文。
接受任務(wù)日期 2008 年 12 月 1 日 要求完成日期 2009 年 5 月 10 日
學(xué) 生 簽 名 年 月 日
指導(dǎo)教師簽名 年 月 日
院長（主任）簽名 年 月 日
畢業(yè)論文題目
學(xué)校代碼：10410
序 號：050411
本 科 畢 業(yè) 論 文
題目： KQYJ-1T空氣壓機設(shè)計
學(xué) 院： 工 學(xué) 院
姓 名： 丁 劍
學(xué) 號： 20050411
專 業(yè)： 機械設(shè)計制造及其自動化
年 級： 機制051
指導(dǎo)教師： 文 建 萍
二OO九年 五 月
- 1 -
摘 要
氣動壓力機（KQYJ-1T）設(shè)計是典型的機械設(shè)計，它包括機構(gòu)的尺寸、強度設(shè)計以及標(biāo)準(zhǔn)氣缸和材料的選擇。主設(shè)計是針對保證每次給壓穩(wěn)定的要求而對倍力氣缸的設(shè)計。設(shè)計主要內(nèi)容包括：設(shè)計方案確定、主氣缸設(shè)計與其它附件及控制電路的設(shè)計。
倍力氣缸的活塞大小，密封性及工作壓力的穩(wěn)定設(shè)計是電控壓力機能否正常工作的關(guān)鍵，也是本設(shè)計重點。主氣缸及個副氣缸（標(biāo)準(zhǔn)缸）的設(shè)計及選擇是實現(xiàn)工作要求的給壓、自動送料和自動清刷裝置等功能的關(guān)鍵所在。
作為電控氣動設(shè)備，控制電路的設(shè)計自然非常重要，由于專業(yè)限制，這塊方案的確定是在公司相關(guān)技術(shù)人員的幫助下完成，主選的是PLC控制方式。而且處于對操作人員的安全考慮，采用了電感應(yīng)行程開關(guān)，這樣大大提高了設(shè)備的安全性能。
設(shè)計好的電控壓力機工作效率為每分鐘6到20次，在工作氣源壓力不小于0.6Mpa的情況提供不大于1T的壓力。
關(guān)鍵詞：倍力氣缸、自動送料裝置、自動清刷裝置、機座、和控制系統(tǒng)。
KQYJ-1T air press design
Abstract: the air operated press (KQYJ-1T) designs is the typical machine design, it including organization size, intensity design as well as standard air cylinder and material choice. The main design is aims at the guarantee each time to give presses the stable request, but to time of strength air cylinder's design. The design primary coverage includes: Design proposal determination, master cylinder design and other appendices and control circuit's design. the time of strength air cylinder's piston size, whether leak-proof and is working pressure's stable design the electrically controlled press normal work key, is also this design key. Master cylinder and vice-air cylinder (standard cylinder) the design and the choice are realize the work requirement for installment the function and so on to press, the feed control and to clean off keys to be at automatically. takes the electric control air operated equipment, control circuit's design is naturally important, because the specialized limit, this plan's determination is completes under the company correlation technique personnel's help, what the host elects is the PLC control mode. Moreover is to operators' security concern, has used the electric induction limit switch, enhanced equipment's safety performance like this greatly. designs the good electrically controlled press working efficiency for each minute 6 to 20 times, is not smaller than in the process gas source pressure the 0.6Mpa situation provides is not bigger than 1T the pressure.
Key words: Time of strength air cylinder, the feed control installment, clean off the installment, the seat-s on a plane automatically, and the control system.
3D 效果圖
各位評委老師好！設(shè)計課題：設(shè)計課題：KQYJ-1T KQYJ-1T 空氣壓機設(shè)計空氣壓機設(shè)計班班 級：級：機制機制051051姓姓 名：丁名：丁 劍劍學(xué)學(xué) 號：號：2005041120050411指導(dǎo)老師：文指導(dǎo)老師：文 建建 萍萍 動力源的選擇：經(jīng)過查閱資料和工作參數(shù)的要求，最后選定用壓縮空氣來作為設(shè)備的動力源，因此選擇氣壓系統(tǒng)作為動力裝置。其具有以下優(yōu)點：(1)(1)介質(zhì)提取和處理方便。介質(zhì)提取和處理方便。(2)(2)阻力損失和泄漏較小，在壓縮空氣的輸送過程中，阻力損阻力損失和泄漏較小，在壓縮空氣的輸送過程中，阻力損失較小。失較小。(3)(3)動作迅速，反應(yīng)靈敏。氣動系統(tǒng)一般只需要動作迅速，反應(yīng)靈敏。氣動系統(tǒng)一般只需要0.02s-0.3s0.02s-0.3s即可即可建立起所需的壓力和速度。氣動系統(tǒng)也能實現(xiàn)過載保護，便于建立起所需的壓力和速度。氣動系統(tǒng)也能實現(xiàn)過載保護，便于自動控制。自動控制。(4)(4)工作環(huán)境適應(yīng)性好。在易燃、易爆、多塵埃、強磁、強輻工作環(huán)境適應(yīng)性好。在易燃、易爆、多塵埃、強磁、強輻射、振動等惡劣環(huán)境中，氣壓傳動與控制系統(tǒng)比機械、電器及射、振動等惡劣環(huán)境中，氣壓傳動與控制系統(tǒng)比機械、電器及液壓系統(tǒng)優(yōu)越，而且不會因溫度變化影響傳動及控制性能。液壓系統(tǒng)優(yōu)越，而且不會因溫度變化影響傳動及控制性能。(5)(5)成本低廉。由于氣動系統(tǒng)工作壓力較低，因此降低了氣動成本低廉。由于氣動系統(tǒng)工作壓力較低，因此降低了氣動元、輔件的材質(zhì)和加工精度要求，制造容易，成本較低元、輔件的材質(zhì)和加工精度要求，制造容易，成本較低 KQYJ-1T 空氣壓機設(shè)備在設(shè)備在220V220V交流電壓和不小于交流電壓和不小于0.6MPa0.6MPa的工作壓力（的工作壓力（常見的現(xiàn)常見的現(xiàn)場工作壓力為場工作壓力為0.5MPa0.5MPa）條件下：完成自動送料出入至施壓點、）條件下：完成自動送料出入至施壓點、給予壓力和清刷沖頭等功能。并要求每次給定的壓力在一定的給予壓力和清刷沖頭等功能。并要求每次給定的壓力在一定的范圍內(nèi)，保證效率在每分鐘范圍內(nèi)，保證效率在每分鐘620620次，所施加的壓力不大于次，所施加的壓力不大于1 1噸噸（即為（即為100MPa100MPa）。）。KQYJ-1T 空氣壓機主要參數(shù)：主要參數(shù)：外形尺寸：（長外形尺寸：（長 寬寬 高）不大高）不大于于（1000mm700mm1800mm1000mm700mm1800mm）。）。最大額定增壓壓力：最大額定增壓壓力：1T1T（100MPa100MPa）。）。最大額定輸出工作壓力最大額定輸出工作壓力:1000Kg:1000Kg。托模上移塊上移的總行程：托模上移塊上移的總行程：140mm140mm。工作效率每分鐘工作效率每分鐘6 6到到2020次。次。工作氣源壓力：工作氣源壓力：0.6Mpa0.6Mpa工作電源電壓：工作電源電壓：220V220V，0.1kw0.1kw。KQYJ-1T KQYJ-1T 主要組成部件主要組成部件送料機構(gòu)送料機構(gòu)清擦機構(gòu)清擦機構(gòu) 倍力氣缸倍力氣缸機架機架KQYJ-1T 空氣壓機的工作原理 HQYJ-1T HQYJ-1T空氣壓機的動力源為壓縮空氣，它是通過使用空氣壓機的動力源為壓縮空氣，它是通過使用倍力氣缸和配重塊來完成對殼體內(nèi)的藥劑進行壓實，由于作倍力氣缸和配重塊來完成對殼體內(nèi)的藥劑進行壓實，由于作用在殼體藥劑內(nèi)的力是一對相互作用力，因此在配重塊不變用在殼體藥劑內(nèi)的力是一對相互作用力，因此在配重塊不變的情況下每次壓裝時殼體內(nèi)藥劑受到的作用力是一致的。的情況下每次壓裝時殼體內(nèi)藥劑受到的作用力是一致的。模子送進模子送進模子送進模子送進 模子放入模座，光點傳感器感應(yīng)觸發(fā)后延時模子放入模座，光點傳感器感應(yīng)觸發(fā)后延時t t秒（可調(diào)），秒（可調(diào)），PLCPLC接接到信號后接通送模氣缸電磁閥電源，送模氣缸進出氣換向，將送?；寮暗叫盘柡蠼油ㄋ湍飧纂姶砰y電源，送模氣缸進出氣換向，將送?；寮胺雷o門拉送到位。防護門拉送到位。工作過程工作過程工作過程工作過程在送模氣缸將送?；寮胺雷o門拉送到位的同時，送模氣缸上的磁石感應(yīng)在送模氣缸將送?；寮胺雷o門拉送到位的同時，送模氣缸上的磁石感應(yīng)開關(guān)接通，開關(guān)接通，PLCPLC接到信號后，電磁閥換向?；钊麠U推動托模上移塊將到位的接到信號后，電磁閥換向。活塞桿推動托模上移塊將到位的模座和模子向上推起，壓藥沖通過脫模導(dǎo)沖板和導(dǎo)沖模進入產(chǎn)品殼體內(nèi)壓模座和模子向上推起，壓藥沖通過脫模導(dǎo)沖板和導(dǎo)沖模進入產(chǎn)品殼體內(nèi)壓實藥劑到位。實藥劑到位。保壓延時保壓延時保壓延時保壓延時在倍力氣缸活塞桿上移壓實殼體內(nèi)藥劑的同時，壓頭對配重塊支架施加向在倍力氣缸活塞桿上移壓實殼體內(nèi)藥劑的同時，壓頭對配重塊支架施加向上的作用力將其頂起，當(dāng)支架托盤遠離接近傳感器時，上的作用力將其頂起，當(dāng)支架托盤遠離接近傳感器時，PLCPLC接到信號后關(guān)閉接到信號后關(guān)閉進氣口，倍力氣缸活塞桿輸出力與配重塊支架重物下壓力平衡，延時進氣口，倍力氣缸活塞桿輸出力與配重塊支架重物下壓力平衡，延時t1t1秒秒（可調(diào)）后，（可調(diào)）后，PLCPLC發(fā)出指令延時電磁閥開始工作，使壓機對壓料延時保壓。發(fā)出指令延時電磁閥開始工作，使壓機對壓料延時保壓。倍力氣缸回位過程倍力氣缸回位過程倍力氣缸回位過程倍力氣缸回位過程PLCPLC延期到時后，延期到時后，倍力氣缸反向進氣，倍力氣缸反向進氣，倍力氣缸活塞桿及倍力氣缸活塞桿及托模托模上移塊下移回位，送模滑板動作將模座和模子一起送出回到起上移塊下移回位，送?；鍎幼鲗⒛Ｗ湍Ｗ右黄鹚统龌氐狡鹗嘉恢?。工作循環(huán)完成。始位置。工作循環(huán)完成。清擦清擦清擦清擦當(dāng)倍力氣缸活塞桿回到位后，清刷計數(shù)到后，清刷缸開始對沖當(dāng)倍力氣缸活塞桿回到位后，清刷計數(shù)到后，清刷缸開始對沖子清刷，清刷的次數(shù)由文本上設(shè)置而定，只有當(dāng)清刷完后，才子清刷，清刷的次數(shù)由文本上設(shè)置而定，只有當(dāng)清刷完后，才可以進入下一個產(chǎn)品的。在清刷過程中如有異?？砂聪录蓖ｉ_可以進入下一個產(chǎn)品的。在清刷過程中如有異常可按下急停開關(guān)停止關(guān)停止清刷。清刷。壓力調(diào)整：壓力調(diào)整：根據(jù)工作需要選擇配重的重量，并將其擺放在配重塊支架上，根據(jù)工作需要選擇配重的重量，并將其擺放在配重塊支架上，配重塊的重量有：配重塊的重量有：20kg20kg（8 8個），個），10kg10kg（2 2個），個），5kg5kg（2 2個），個），2kg2kg（4 4個），個），1kg1kg（2 2個）。個）。感謝各位評委老師！由于能力有限，設(shè)計還不是那么的完善，希望各位評由于能力有限，設(shè)計還不是那么的完善，希望各位評委老師給出寶貴的意見！委老師給出寶貴的意見！目 錄 前言 .- 1 - 第一章 電控氣動壓力機方案設(shè)計 .- 2 - 1.1 設(shè)計任務(wù)抽象化 .- 2 - 1.1.1 建立黑箱 .- 2 - 1.1.2 功能分解 .- 2 - 1.2 確定工藝原理 .- 3 - 1.3 確定技術(shù)過程 .- 4 - 1.4 引進技術(shù)系統(tǒng)，確定邊界 .- 4 - 1.5 確定功能結(jié)構(gòu) .- 5 - 1.5.1 技術(shù)系統(tǒng)總功能，及進行功能分解 .- 5 - 第二章 倍力氣缸設(shè)計 .- 6 - 2.1 工作動力類型的選擇 .- 6 - 2.2 氣缸及其附件的設(shè)計 .- 7 - 2.2.1 氣缸的設(shè)計和計算 .- 7 - 第三章 自動送料機構(gòu)設(shè)計 .- 10 - 3.1 送料滑板設(shè)計 .- 10 - 3.2 定位、脫模調(diào)節(jié)設(shè)計 .- 11 - 3.3 送料裝置氣缸的選擇 .- 11 - 第四章 清擦機構(gòu)的設(shè)計 .- 12 - 4.1 清擦機構(gòu)設(shè)計方案分析 .- 13 - 4.2 清擦機構(gòu)機構(gòu)的確定 .- 13 - 第五章 機座部分 .- 15 - 5.1 配重塊 .- 15 - 5.2 安全措施 .- 16 - 5.3 臺面板 .- 16 - 5.4 機架 .- 16 - 5.5 其余材料 .- 16 - 5.6 配重塊 .- 16 - 第六章 電路、氣路控制 .- 16 - 6.1 模子送進 .- 19 - 6.2 工作過程 .- 19 - 6.3 保壓延時 .- 19 - 6.4 倍力氣缸回位過程 .- 19 - 6.5 模子送出 .- 19 - 6.6 清刷過程 .- 19 - 參 考 文 獻 .- 20 - 致 謝 .- 21 -
編 號 20050411
江西農(nóng)業(yè)大學(xué) 工學(xué)院
畢業(yè)設(shè)計材料
題 目
KQYJ-1T 空氣壓機設(shè)計
專 業(yè)
機械設(shè)計制造及其自動化
學(xué)生姓名
丁 劍
材 料 目 錄
序號
附 件 名 稱
數(shù)量
備注
1
畢業(yè)設(shè)計論文
1
2
設(shè)計圖紙
1份
二〇〇九年五月
Proceedings of the 7th ICFDM2006 International Conference on Frontiers of Design and Manufacturing June 19-22, 2006, Guangzhou, China Pages 25-30 25 STUDY OF THE INFLUENCE THE INFLUENCE OF LOW ENVIRONMENT PRESSURE ON THE BEARING In ICE Feng Kai, Zhang Youyun and Xin Hao Theory of Lubrication and Bearing Institute, Xian Jiaotong University, Xian 710049, China Abstract: The influence of low environment pressure on the main bearing and big end bearing of I.C. engine was investigated based on a one-cylinder diesel engine. Firstly, a model of one-cylinder engine was set up, by the use of the commercial software EXCITE Designer from AVL company. Then, a series of experiments were done to gain the gas pressure in cylinder under different environment pressure. When the model of the engine considered the gas pressure as load, the applied load, eccentricity ratio and friction loss of the main bearing and the big end one were calculated, with the results validated by the experiments. The calculation results show that, with the decrease in environment pressure, the applied load of main bearing and big end one change, and the eccentricity ratio vary regularly, while their friction loss decrease a little. KeyWords: I.C. Engine; Low Environment Pressure; Bearing Load; Eccentricity Ratio; Friction Loss 1. Introduction Most of western China is high altitude plateau. As the increase of altitude, the air pressure and air density decrease, the air draw into the engine reduces and the combustible mixed gas becomes too dense ， so the combustion process becomes worse and dynamic behavior of the engine deteriorate significantly 1 . Under this working condition, the performance of both the main bearing and concord bearing will be affected by the drop of air pressure. So the research on the working condition of engine main bearing and concord bearing under western low pressure environment has important guiding significance for the design, manufacture and maintenance of engines working under western environment. At present, research documents on engine combustion process and dynamics influence at different altitude are usual at home and abroad 23 , but no systematic research work on the influence of low air pressure to the engine bearing appears. In this paper, single cylinder engine model considered the influence of air pressure is constructed. Using the combustion gas pressure measured through experiment under different environment pressure and different rotate speed as the input loading condition of the model, the change of the working condition of main bearing and concord bearing along with the environment air pressure under different rotate speed is calculated with business software EXCITE Designer of AVL Company, and the result is compared and validated with the experimental locus of journal center. 2. The Processing Method of low Air Pressure The influence of plateau low air pressure to the performance of engine bearing mainly comes from the deterioration of the engine dynamic behavior. In this paper, a western environment simulation engine test rig is used to simulate plateau low air pressure and measure the influence of low air pressure to the engine. The key technology of simulating low air pressure environment is how to simulate and adjust the intake pressure of the engine 4 . The exhaust pressure and the pressure in the crank shaft case are not simulated in this test system, and these works will be done later on. In the experiment, the influence of different intake pressure on the pressure in the cylinder is measured and the pressure value is loaded to the model constructed below, and then the influence of low pressure on the performance of engine bearing is worked out. The structure of the test rig is showed in fig. 1. Through the control of engine intake pressure, the simulation case can simulate the working condition of the engine under different environment air pressure. Then the pressure in the cylinder of the engine is measured by the high pressure and high temperature pressure sensor implemented in the cylinder. Due to the restriction of experimental condition, the eccentricity of the main bearing can not be measured directly, so the locus of journal center of the flywheel is measured with vortex sensor, and its eccentricity is worked out to replace that of the main bearing to validate the computational model. There are various factors which affect the combustion gas pressure in the cylinder, among which environment air pressure, rotate speed and load are especially important. Consider to run the engine with no load (the engine mainly do work to overcome friction) and measure Fig. 1 View of the Simulation Test Rig * Sponsored by National Natural Science foundation of China 26 the pressure in the cylinder under different rotate speed and different environment pressure. Fig.2 shows the pressure in the cylinder under different environment air pressure at 1000r/m. 3 The Influence of low Air Pressure on the Load of Engine Bearings 3.1 Force analysis of the piston-shafting system In order to simplify the model, it is assumed that the piston pin and rotate axis of the crank shaft are all on the central line of the piston. Then the force analysis of the engine piston-shafting is showed in fig.3. The gas pressure in the cylinder F Z is disassembled to the bearing. Fig.3 Piston-Shafting Force Analysis and Inertial Force Analysis 22 11 cos 1sin SS Z Z FF F F = = (1) 22 sin tan 1sin NN Z Z FF F F = = (2) () 2 22 sincos cos cos 1sin RZ Z FF F + = = (3) () 22 sin sin cos sin cos 1sin RZ Z FF F + = = + (4) F Z is the combustion gas pressure in the cylinder, the input load of the model; F T and F R are the forces applied on the concord big end bearing; FZ and FS are the force applied on the main bearing. 3.2 Inertial force analysis of the piston-shafting In this paper, two kinds of inertial force are considered as shown in fig.3 1) Rotate inertial force along the crank shaft radial direction 2) 1 st and 2nd order reciprocal inertial force along the piston central axis direction Disassemble to coordinate system: ( ) 0 2 01 0 cos cos cos 2 Zr Fr m mA mA = + + +K (5) 2 sin ry Fr m = (6) Through force analysis of piston-shafting of the engine, combustion gas pressure in the cylinder is disassembled to the main bearing and concord big end bearing, at the same time the inertial force caused by the movement of the piston-shafting system. The load force on the main bearing and concord big end bearing can be derived from the combination of these two kinds of force. 3.3 Calculation result and analysis of bearing load Fig.2 Gas Pressure in the Cylinder under Different Environment Pressure at 1000r/m (a) 1000r/m Main Bearing Load (b) 1800r/m Main Bearing Load (d) 1000r/m Concord Big End Bearing Load (c) 2200r/m Main Bearing Load 27 Fig.5 Main Bearing and Concord Big End Bearing under Different Rotate Speed and Different Environment Pressure Fig.5 shows that as the environment air pressure decreases, the load of main bearing and the concord big end bearing significantly reduces during the deflagration stroke, and slightly changes during other strokes. Read in and analysis the load of the main bearing and concord big end bearing during the deflagration stroke, the results are showed in form 1: Form 1 Analysis of the Load of Main Bearing and Concord Big End Bearing during Deflagration Stroke under Different Environment Pressure and Different Rotate Speed Main Bearing Environment Pressure (kPa) 97 80 60 Bearing Load (kN) 16000 13500 110001000 r/m Decrease Percent (relative to 97kPa) 15.6 31.3 Bearing Load (kN) 14000 10000 4500 1800 r/m Decrease Percent 28.6 67.8 Bearing Load (kN) 9000 5000 3000 2200 r/m Decrease Percent 44.4 66.7 Concord Big End Bearing Environment Pressure (kPa) 97 80 60 Bearing Load (kN) 32500 27500 225001000 r/m Decrease Percent 15.4 30.8 Bearing Load (kN) 28000 20000 100001800 r/m Decrease Percent 28.6 64.3 Bearing Load (kN) 20000 11500 8000 2200 r/m Decrease Percent 42.5 60.0 It shows in form 1 that the load of the main bearing and concord big end bearing will decreases along with the reduce of environment air pressure at any speed. The lower the air pressure, the more significant the load decreases. As the rise of engine rotate speed, the decrease of the deflagration load of the main bearing and the concord big end bearing augment becomes more significant. In another word, the higher the engine rotate speed, the more sensitive the deflagration load of the main bearing and concord big end bearing is to the environment air pressure. The reason of this situation is that as the engine rotate speed rises, the decrease of the pressure in the cylinder increases, then the load of the bearing reduces significantly. Further more, as the rotate speed rises, the inertial force augment, but the load of the bearing reduces under the combinational influence. However, when the rotate speed rises to 1800r/m and the air pressure drops to 60kPa, the decrease of the deflagration load of the main bearing and concord big end bearing do not change along with the rise of the engine rotate speed. It means that when the rotate speed rise to a certain extent, and the environment air pressure is low enough, the influence of the environment air pressure to the load of the bearing in deflagration process is almost the same at different rotate speed. This is because when the environment air pressure decrease to a certain extent, and the rotate speed is upper, the influence of the air pressure to the combustion in the cylinder decreases, at the same time the pressure in the cylinder is pretty high, and the effect of the inertial force is minor, so the bearing load keeps unchanged to a large extent. Fig.5(c) (f) shows the change of the load of the main bearing and concord big end bearing in relation to the crank angle at the rotate speed of 2200r/m. It shows in the figure that the decrease or increase of the load of the two bearing is not congruously along with the diminishment of the environment air pressure in the whole working process of the engine, but differ in different strokes. This phenomenon can be explained as follows: In the whole working process of the engine, the air pressure in the cylinder (F Z in formula (1)-(4) especially the combustion gas pressure in the deflagration process decreases along with the decrease of the environment air pressure, so the load of the main bearing and concord big end bearing decreases as a whole. The increase of bearing load when the crank angle is between 300 360 and -360 -300 is because the piston is in the latter half of exhaust stroke and the first half of air intake stroke at that time, and the cylinder is exchanging air with the environment; here the inertial force along the negative direction of z axis F Z is smaller than that along the positive direction of z axis, it means that the resultant force is along the positive direction of z axis, as F Z diminish, the resultant force will augment on the contrary, so the bearing load will increase. 4 The influence of low Air Pressure to the Eccentricity of the Engine Bearing 4.1 The establish of Reynolds equation and the solving of the eccentricity The Reynolds equation of the engine bearing can be expressed as 5 : () () () () () 2 33 * 1 cos 1 cos 22 6sin sin cos D BR z dd dt dz + = + (7) In which D is the diameter of the bearing bush, BR is the width of the bearing bush, is the eccentricity, (e) 1800r/m Concord Big End Bearing Load (f) 2200r/m Concord Big End Bearing Load 28 is the dynamic viscosity of the engine oil, is the minimum gap angular velocity, is the rotate speed of the journal. is the oil film pressure, t is the time coordinate, and z are dimensional coordinate. Analyze the increase and decrease process of the bearing eccentricity respectively, the relation of the differential coefficient of eccentricity and the journal rotate speed can be expressed as below: () 2 Psin cos tan / , V B B So BR D BR D null null nullnullnull (8) () 2 * sin sin / , D PB So BR D BR D = null null nullnullnull (9) In which B= S S 0 B 90 In the calculation Butenschoen method is used, and Sommerfeld number S OD and S OV can be find in reference 5, then Runge-Kutta method is used to solve the eccentricity through loop iteration. 4.2 Computing result and analysis of the bearing eccentricity Fig.6 Eccentricity of the Main Bearing and Concord Big End Bearing under Different Environment Air Pressure. Fig.6 (a) (d) show that when the engine rotate speed is under 1000r/m, both of the eccentricity shape of the two bearing shrink; fig.6 (b) (e) show that when the speed is 1800r/m, both of the eccentricity shape expand, and the deviation direction of the main bearing changed; and fig.6 (c) (f) show that when the rotate speed is 2200r/m, both of the eccentricity of the two bearing expand. We can conclude from the above figures that when the engine rotate speed is lower, the eccentricity shape of the main bearing and concord big end bearing shrink as the decrease of the environment air pressure, the lubrication condition of the bearing is improved and the bearing works more stable; when the rotate speed is higher, the eccentricity shape of the two bearing expand on the (a) 1000r/m Main Bearing Eccentricity (b) 1800r/m Main Bearing Eccentricity (c) 2200r/m Main Bearing Eccentricity (d) 1000r/m Concord Big End Bearing Eccentricity (e) 1800r/m Concord Big End Bearing Eccentricity (f) 2200r/m Concord Big End Bearing Eccentricity 29 contrary, the lubrication condition deteriorate and the bearing works unstable. At specific rotate speed, the deviation of the eccentricity may also change as the environment air pressure decreases. The load of the bearing is determined by the resultant force of the combustion gas pressure and the reciprocating inertial force of the shafting. When the rotate speed is lower, the reciprocator inertial force is lesser, and the main load of the engine bearing is caused by the combustion gas pressure in the cylinder (this is also the reason why the bearing eccentricity deflect to one side of the axis center). For this reason, the decrease of the environment air pressure causes the decrease of the pressure in the cylinder, thus the bearing eccentricity shrink. But when the engine rotate speed is higher, the reciprocating inertial force of the shafting increases and may at specific crank angle exceeds the combustion gas pressure in the cylinder if rotate speed is high enough. This makes the shape of the bearing eccentricity deflect to another side of the shaft center. At this time, when the decrease of environment air pressure causes the decrease of the pressure in the cylinder, the deflection of the bearing eccentricity also changes. As the engine rotate speed keeps on increasing, the reciprocating inertial force of the shafting exceeds the pressure in the cylinder in a bigger range of the crank angle. As a result, the bearing load is the result of the reciprocating inertial force minus the combustion gas pressure in the cylinder. When the decrease of the environment air pressure causes the decrease of the pressure in the cylinder, the load of the bearing increases and the eccentricity augments. 5. The influence of low Air Pressure to the Friction Power loss of Engine Bearing 5.1 The calculation of the friction power loss 5 If there is no direct contact between the bearing journal and bush, most of the friction power loss is caused by the shearing force of the engine oil viscosity. In this paper, only this part of friction power loss is considered. The friction coefficient () is: () () 4 sin 21 D So =+ (10) () () 2 * D D F So BR D = (11) Then the friction power loss is: () () () 2 4 * 0 42 Z FD BR D PSod = (12) 5.2 Calculation result and analysis of friction power loss of the bearing Fig.7 Friction Power Loss of the Main Bearing and Concord Big End Bearing under Different Environment Air Pressure It is figured out in Fig.7 that the power loss of the main bearing and concord big end bearing caused by the engine oil viscosity minish slightly along with the decrease of the environment air pressure. This is because the bearing load decrease as a whole when environment air pressure decreases, and the oil viscosity also reduces along with the increase of pressure 6 , thus the shearing force caused by the oil viscosity also decrease slightly, so the friction power loss reduces. Furthermore, it is shown in the fig that the influence of environment pressure to the friction power loss is relatively more significant during the deflagration stroke. This is also because the decrease of the bearing load is more severe at that time. 6. Experimental Verification Measure the locus of journal center of the flywheel with vertex displacement sensor on the “Western environment engine test rig” and calculate its eccentric, and then use it instead of the eccentricity of the main bearing to verify the computational model. (a) 2200r/m Main Bearing Friction Power Loss (a) 2200r/m,97kPa Calculated Eccentricity of the Main Bearing (b) 2200r/m,97kPa Eccentricity at the Fly Wheel Measured Through Experiment (b) 2200r/m Concord Big End Bearing Friction Power Loss 30 Fig 8 Eccentricity of Main Bearing Because of the restriction of experimental condition, the eccentricity of the main bearing can not be measured directly, so the eccentricity measured in the experiment is that of the flywheel. Because the crank shaft is flexible and will bend and distort under the stress of the concord and the engine cabinet, the eccentricity of the main bearing and the flywheel, which are at different section of the crank shaft, is apparently different. But there should be some common characteristics between them; the movement condition should be the same, and the locus of journal center should be similar. This is mainly because the main bearing and the flywheel are both on the crank shaft and the distance between them is not long, so the bend and distortion of the crank shaft is limited, thus the eccentricity shape is similar to some extent. Furthermore, because they are both on the crank shaft, and both have the same load, the change trend of the eccentricity should be the same. In this paper, the eccentricity at the flywheel measured through experiment and the calculated eccentricity of the main bearing are compared to verify the computational model. Fig.9 The movement condition of the eccentricity As shown in fig.8, it can be seen from the shape of the two graphics and the order of the marked point that both of them are moving according to the direction in fig.9 from A to B, C H in turn. Compared to fig.8 (a), point A, G and H in fig.8 (b) deflect a little to the right, and point F deflects slightly up. This is mainly caused by the distortion of the crank shaft. Through the analysis and comparison of the two figure above, we can see that the movement rule of the two eccentricity are consistent, and the shape of them are similar to some extent. So we can come to the conclusion that the computational result is verified correct and credible through experiment. 7. Conclusion In this paper, single cylinder engine model considered the influence of low air pressure to the main bearing and concord big end bearing is constructed and verified through experiment. Generally, the higher the rotate speed of the engine, the more sensitive the deflagration load of the main bearing and the concord big end bearing to environment air pressure. But when the environment air pressure decreases to a certain extent, its influence to the deflagration load of the main bearing and the concord big end bearing of high rotate speed engine no longer exist; and the influence of the environment air pressure to deflagration load of the engine main bearing and concord big end bearing is the to the same extent. Along with the decrease of environment air pressure, the eccentricity of the main bearing and the concord big end bearing change regularly. When th
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