汽車萬(wàn)向傳動(dòng)裝置設(shè)計(jì)及有限元分析
汽車萬(wàn)向傳動(dòng)裝置設(shè)計(jì)及有限元分析,汽車,萬(wàn)向,傳動(dòng),裝置,設(shè)計(jì),有限元分析
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設(shè)計(jì)(論文)題目:汽車萬(wàn)向傳動(dòng)裝置設(shè)計(jì)及有限元分析
學(xué)生姓名:
任務(wù)書填寫要求
1.畢業(yè)設(shè)計(jì)(論文)任務(wù)書由指導(dǎo)教師根據(jù)各課題的具體情況填寫,經(jīng)學(xué)生所在專業(yè)的負(fù)責(zé)人審查、系
(院)領(lǐng)導(dǎo)簽字后生效。此任務(wù)書應(yīng)在畢業(yè)設(shè)計(jì)(論文)開始前一周內(nèi)填好并發(fā)給學(xué)生。
2.任務(wù)書內(nèi)容必須用黑墨水筆工整書寫,不得涂改或潦草書寫;或者按教務(wù)處統(tǒng)一設(shè)計(jì)的電子文檔標(biāo)準(zhǔn)格式
(可從教務(wù)處網(wǎng)頁(yè)上下載)打印,要求正文小4號(hào)宋體,1.5倍行 , 打印在 上 。
3.任務(wù)書內(nèi)填寫的內(nèi)容,必須 學(xué)生畢業(yè)設(shè)計(jì)(論文) 的情況 一 , 有 ,應(yīng) 經(jīng) 所在專業(yè)及
系(院) 領(lǐng)導(dǎo)審 后 可 填寫。
4.任務(wù)書內(nèi)有 學(xué)院 、 專業(yè) 名 的填寫,應(yīng)寫 文 ,不 寫 字?¢。學(xué)生的 學(xué)號(hào) 要寫
號(hào),不 £寫?后2¥或1¥ 字。
5.任務(wù)書內(nèi) 要?§文currency1 的填寫,應(yīng)按'“???fi學(xué)院fl?畢業(yè)設(shè)計(jì)(論文) 寫–??的要求書寫。
6.有 · ? ??的填寫,應(yīng) 按'?標(biāo)GB/T 7408—94“ 據(jù)元 ?”格式、?…?”、?? ‰
? `?–′的要求,一?用?ˉ? 字書寫。˙ 2002·4 2? 或 2002-04-02”。
畢 業(yè) 設(shè) 計(jì)(論 文)任 務(wù) 書
1.fl畢業(yè)設(shè)計(jì)(論文)課題應(yīng)¨ 的目的:
在 畢業(yè)設(shè)計(jì)的 ? ,? 學(xué)生??分析 ˇ— 題的 學(xué) 工 , 學(xué)生的 fl
。? 學(xué)生 在 的 文currency1 行? ,學(xué)a??用 課題 的文currency1的 , 后的工 ′
一′的 行 分析 題并ˇ— 題的 。 ?好的工 ??、o 的工 。
2.fl畢業(yè)設(shè)計(jì)(論文)課題任務(wù)的內(nèi)容 要求( 始 據(jù)、fi?要求、工 要求 ):
設(shè)計(jì)內(nèi)容:
1.分析汽車萬(wàn)向傳動(dòng)裝置 fl 工 ;
2.?用 CATIA?汽車萬(wàn)向傳動(dòng)裝置 行??
3.?用有限元分析 ANSYS?萬(wàn)向傳動(dòng)裝置的 要? 行 ?分析。
工 要求:
1.要求在畢業(yè)設(shè)計(jì) ? ,應(yīng)有o 的?學(xué)??,o 求實(shí)的工 ;
2.依據(jù)課題設(shè)計(jì)任務(wù), 行資料收集、閱讀、整 ,正確使用工具書 網(wǎng)絡(luò),熟練掌握 計(jì)算
`,按‰ 開題報(bào)告、 文?§資料 內(nèi)容;
3.要求?用 CATIA 行??,掌握有限元分析 `,并將 汽車設(shè)計(jì)、機(jī)械制圖、機(jī)械設(shè)計(jì)、材料
學(xué)、計(jì)算機(jī) 有機(jī) ?、熟練?用
4.按‰?加答辯,答辯前各項(xiàng)–′的資料要 整、齊 。
畢 業(yè) 設(shè) 計(jì)(論 文)任 務(wù) 書
3.?fl畢業(yè)設(shè)計(jì)(論文)課題 果的要求〔 圖?、實(shí)物 硬 要求〕:
1. ?用 CATIA?汽車萬(wàn)向傳動(dòng)裝置 行??,?用有限元分析 ANSYS?萬(wàn)向傳動(dòng)裝置的 要?
行 ?分析。
2.畢業(yè)設(shè)計(jì)1.5萬(wàn)字左右;
3. 文?§資料譯文(附 文)3000字。
4. 要?§文currency1:
[1] 孫啟a,閔鵬.有限元`在汽車車架分析 的應(yīng)用[J]. 型汽車, 2011(05):20-21.
[2] 張鐵山, 胡? , 唐云. 輕型汽車車架動(dòng)?有限元分析[J]. 南京 工 學(xué)學(xué)報(bào), 2004,
25(6):588-591.
[3] 莊茁. 于ABAQUS的有限元分析 應(yīng)用[M]. 清華 學(xué)出版社, 2009.
[4] 尤春 . CATIA V5機(jī)械設(shè)計(jì)[M]. 清華 學(xué)出版社, 2002.
[5] 胡海龍. CATIA V5R18 礎(chǔ)設(shè)計(jì)[M]. 清華 學(xué)出版社, 2010.
[6] 鐘佩思, 趙丹, 孫雪顏 . 于ANSYS的汽車車架的?? ??分析[J]. 機(jī)械設(shè)計(jì) 制造,
2008(6):52-53.
[7] 張 ?, ?曉輝, 孫敬宜. 于ANSYS的汽車車架 有限元分析[J]. 拖ˉ機(jī) 農(nóng)用?輸車,
2006, 33(5):63-64.
[8] 鐘佩思, 孫雪顏, 趙丹 . 于ANSYS的貨車車架的有限元 ?分析[J]. 拖ˉ機(jī) 農(nóng)用?輸車,
2008, 35(2):89-90.
[9] 韓璐, 司景萍, 李臣. 于ANSYS 的車架設(shè)計(jì)研究?述[J]. 專用汽車, 2008(3).
[10] 于淼, 杜俊廷, 魯植雄. 于ANSYS的FSC車架有限元分析[J]. 農(nóng)業(yè)裝備 車輛工?, 2014,
52(9):20-22.
[11]
[12] 丁志寶, 文學(xué)洙. 于ABAQUS的某車架 ? 強(qiáng)?的有限元分析[J]. 機(jī)械工?師,
2013(4):58-59.
[13] 高衛(wèi)民, 王宏雁. 汽車 分析有限元`[J]. 汽車研究 開發(fā), 2005(6):30-32.
[14] 魯?霞, 茍惠芳. 有限元`的 fl思想 發(fā) ?[J]. 機(jī)械 開發(fā), 2009, 24(2):74-75.
[15] 曹妍妍, 趙登峰. 有限元??分析 論及 應(yīng)用[J]. 機(jī)械工? 自動(dòng)化, 2007(01):73-74.
[16] 曾攀. 有限元分析及應(yīng)用[M]. 清華 學(xué)出版社, 2004.
[17] 趙登峰, 魏?華, 元 , . 車車架 動(dòng)??計(jì)算分析[C]// 2006 LMS ?用 a.
2006.
[18] 韓衛(wèi)衛(wèi), 李 . 動(dòng) 論在汽車車架改型設(shè)計(jì) 的應(yīng)用[J]. 業(yè)fi?學(xué)院學(xué)報(bào), 2008,
21(4):27-28.
[19] , . 于車架的 動(dòng)?? `應(yīng)用研究[J]. 電 fi?, 2012, 08(24).
[20] , 張? . 汽車 有限元分析[M]. 清華 學(xué)出版社, 2009.
[21] 志生. 汽車 論( 3版)[M]. 機(jī)械工業(yè)出版社, 2005.
[22] . 載貨汽車車架??分析[J]. 機(jī)電工?, 2008(02):47-49.
[23] , ? . 汽車車架設(shè)計(jì)計(jì)算的有限元`[J]. 汽車fi?, 2007(06).
[24] , , ?雪 . 于Hypermesh的車架 ??分析[J]. 電 fi?, 2008,
2(12).
[25] 王¢£. 于Hypermesh的 車車?¥架有限元分析[D]. ? 學(xué), 2013.
畢 業(yè) 設(shè) 計(jì)(論 文)任 務(wù) 書
5.fl畢業(yè)設(shè)計(jì)(論文)課題工 ?計(jì)§:
2015.12.05-2015.12.22
2015.12.23-2016.01.22
2016.01.23-2016.04.15
2016.04.16-2016.05.04
2016.05.05-2016.05.09
2016.05.10-2016.05.16
確′currency1題,填寫審題?;指導(dǎo)教師下發(fā)任務(wù)書,學(xué)生查閱課題 ?§文currency1、資料, 寫開題報(bào)告。
'?開題報(bào)告、 文?§資料及譯文、畢業(yè)設(shè)計(jì)(論文) “;開始畢業(yè)設(shè)計(jì)(論文)。
具體設(shè)計(jì)或研究 ?實(shí)?,'?畢業(yè)設(shè)計(jì)(論文)草?,填寫 ??查?。
論文或設(shè)計(jì)fi 書、圖 材料,'?畢業(yè)設(shè)計(jì)(論文)′?,指導(dǎo)fl師審 。
'?畢業(yè)設(shè)計(jì) –文檔,學(xué)生準(zhǔn)備答辯;?閱教師?閱學(xué)生畢業(yè)設(shè)計(jì)(論文)。
根據(jù)學(xué)院統(tǒng)一 ?, 行畢業(yè)設(shè)計(jì)(論文)答辯。
所在專業(yè)審查· :
?
負(fù)責(zé)人: 2016 · 1 12 ?
畢 業(yè) 設(shè) 計(jì)(論 文)開 題 報(bào) 告
設(shè)計(jì)(論文)題目:汽車萬(wàn)向傳動(dòng)裝置設(shè)計(jì)及有限元分析
學(xué)生姓名:
開題報(bào)告填寫要求
1.開題報(bào)告(含“文獻(xiàn)綜述”)作為畢業(yè)設(shè)計(jì)(論文)答辯委員會(huì)對(duì)學(xué)生答辯資格審查的依據(jù)材料之一。此
報(bào)告應(yīng)在指導(dǎo)教師指導(dǎo)下,由學(xué)生在畢業(yè)設(shè)計(jì)(論文)工作前期內(nèi)完成,經(jīng)指導(dǎo)教師簽署意見及所在專業(yè)審查
后生效;
2.開題報(bào)告內(nèi)容必須用黑墨水筆工整書寫或按教務(wù)處統(tǒng)一設(shè)計(jì)的電子文檔標(biāo)準(zhǔn)格式打印,禁止打印在其它紙
上后剪貼,完成后應(yīng)及時(shí)交給指導(dǎo)教師簽署意見;
3.“文獻(xiàn)綜述”應(yīng)按論文的框架成文,并 書寫(或打?。┰?開題報(bào)告 一 目?jī)?nèi),學(xué)生寫文獻(xiàn)綜述的
文獻(xiàn)應(yīng) 15 ( );
4.有 期的填寫,應(yīng) 按 標(biāo)GB/T 7408—94 據(jù)元 交 格式 交 期 時(shí) ?
¢£?¥?的要求,一§用currency1'“ ?書寫。?“2004 4 26 ”或“2004-04-26”。
5 開題報(bào)告(文獻(xiàn)綜述)??fi按fl? –?書寫,? ·1.5 。
畢 業(yè) 設(shè) 計(jì)(論文) 開 題 報(bào) 告
1.??畢業(yè)設(shè)計(jì)(論文)?題?”,?據(jù)所查…的文獻(xiàn)資料,‰ ?寫 1000? `的文獻(xiàn)綜述:
一 前′萬(wàn)向傳動(dòng)裝置 1901 應(yīng)用在汽車?業(yè),?開?ˉ用 汽車?向˙。汽車萬(wàn)向傳動(dòng)裝置ˉ汽車傳動(dòng)
¨的 要?成,它一?由萬(wàn)向 傳動(dòng)??成,ˇ要用—在工作 對(duì) 置 的 ?? 傳 動(dòng)
動(dòng) 。汽車萬(wàn)向傳動(dòng)裝置傳統(tǒng)的設(shè)計(jì) , ? ,a ? 。 此 ??要一?o的準(zhǔn) 的
的 ?£。? ACE ?—? ??用,?? ACE 的應(yīng)用 給萬(wàn)向傳動(dòng)裝置的設(shè)計(jì) —
?大便利。二 ?題 背景 意義萬(wàn)向 傳動(dòng)?在汽車工業(yè)發(fā)展的 起到了極其 要的作用。?設(shè)計(jì)
萬(wàn)向 傳動(dòng)裝置應(yīng) 滿足?下要求:保證所連 的 ? 對(duì) 置在預(yù)計(jì)范圍內(nèi) 動(dòng)時(shí) a 的傳動(dòng)扭矩。保證
所連 的 ? 夠均勻的旋?,?且由 ?之 的夾角?產(chǎn)生的慣? 矩所引起的載荷應(yīng)降低到許a范圍內(nèi)。
保證傳動(dòng)效率高,?構(gòu)簡(jiǎn)單,壽命長(zhǎng),維修?便。三 ?題 領(lǐng)域的現(xiàn)狀 動(dòng)態(tài)及發(fā)展?向 前計(jì)算機(jī)輔助
工 隨著計(jì)算機(jī)技術(shù)的飛速發(fā)展已經(jīng)普遍用 各?工 領(lǐng)域。它的作用:(1)完成 工難以完成的龐大的
計(jì)算;(2)在設(shè)計(jì)階段,實(shí)?沒有制造出—, 進(jìn)?實(shí)?實(shí)驗(yàn),但卻a以進(jìn)?仿真分析,有利 進(jìn)設(shè)計(jì),
減 用 實(shí)?實(shí)驗(yàn)的費(fèi)用;(3)精度較高, 近 實(shí)驗(yàn)?果。 前,對(duì)傳動(dòng)?進(jìn)?有限元分析的項(xiàng)目 :
(1) ?構(gòu)靜 分析 1)在靜 作用下,得出整個(gè)傳動(dòng)裝置的應(yīng) 分布,從?全面掌握整個(gè)傳動(dòng)裝置的應(yīng)
分布, ?其 度較大 較 的 置并驗(yàn)證之前的計(jì)算。 2)在靜 作用下,得出傳動(dòng)?部分的彎曲 形與應(yīng)
分布,從?了解傳動(dòng)?承受靜載荷的?”,以及所產(chǎn)生的形 ˉ否在a允許范圍之內(nèi)。 3)在 作用下對(duì)
傳動(dòng)?進(jìn)??度分析,以 ?其彎曲 形ˉ否在允許的范圍內(nèi)。(2)對(duì) 同材料的傳動(dòng)?承載進(jìn)?靜態(tài)分析,
從? ?傳動(dòng)?輕量化設(shè)計(jì)?案,同時(shí)從材料成 的角度分析輕量化?案的優(yōu)劣?。(3)對(duì)傳動(dòng)?的扭??
度進(jìn)?分析,在此基礎(chǔ)上對(duì)傳動(dòng)?的?構(gòu)進(jìn)?優(yōu)化。大量使用有限元?£對(duì)汽車傳動(dòng)¨部 進(jìn)?設(shè)計(jì)與分析,
將使部 的設(shè)計(jì)更加?理 a 。未—,針對(duì)汽車設(shè)計(jì)的CAE分析將更加精 化, 度 將隨之 高,
但汽車設(shè)計(jì)的 期會(huì) ,開發(fā)成 將會(huì)降低。 前的萬(wàn)向傳動(dòng)裝置設(shè)計(jì) ˉ 較單目標(biāo)化的設(shè)計(jì),?實(shí)
計(jì)算? , 目標(biāo)化設(shè)計(jì) 單目標(biāo)設(shè)計(jì)更加全面 ?理。 ??的優(yōu)化算£ 計(jì)算機(jī) 出的汽車萬(wàn)向
傳動(dòng)裝置的 目標(biāo)化的 學(xué) 更 ?將—的發(fā)展 。 目標(biāo)化的萬(wàn)向傳動(dòng)裝置將會(huì)ˉ未—的ˇ 。–
? ?題 車 的 據(jù)對(duì)其萬(wàn)向傳動(dòng)裝置進(jìn)??構(gòu)設(shè)計(jì), 后對(duì)利用ANSYS分析 對(duì)其 傳動(dòng)?
進(jìn)?有限元分析,ˇ要對(duì)傳動(dòng)?進(jìn)?靜 作用下的?度分析, 分析 據(jù),得出?論,對(duì) ?理之處 出優(yōu)
化?案,為傳動(dòng)裝置的進(jìn)一 優(yōu)化設(shè)計(jì) 。 a以 萬(wàn)向傳動(dòng)裝置?成的開發(fā) 期,降低開發(fā)成 。
文獻(xiàn): [1] .汽車設(shè)計(jì) [M]. 4 . ?:機(jī)¢工業(yè)出 £,2004. [2] ?¥,?
§.CATIA V5機(jī)¢(汽車)產(chǎn)currency1全精 教 [M]. ?: '交 出 £,2007. [3] o“,???.有
限元£基礎(chǔ)及ANSYS應(yīng)用[M]. ?:fi學(xué)出 £, 2008. [4]fl長(zhǎng) ,許 –,?文.汽車?向傳動(dòng)¨統(tǒng)??
?萬(wàn)向 傳動(dòng)優(yōu)化設(shè)計(jì)及 動(dòng)仿真分析[J]. ·工學(xué) 學(xué)報(bào), 2009,23(9):20~24. [5] ·,?
·.汽車設(shè)計(jì)? 設(shè)計(jì)指導(dǎo)書 [M]. ?:機(jī)¢工業(yè)出 £,2009. [6] ???.汽車構(gòu)造:下 [M]. 3
. ?:機(jī)¢工業(yè)出 £,2009. [7] ?”.汽車?…設(shè)計(jì) [M]. ?:‰ 大學(xué)出 £,2010. [8]
? .汽車萬(wàn)向 ???`效分析[J].機(jī)¢工 師, 2011(7):174~175. [9] ?′?,?ˉ?. ???
萬(wàn)向 ˙¨?¨ ? 分析[J].機(jī)¢fi學(xué)與技術(shù), 2011,30(12):67~72. [10]? ?,?進(jìn),ˇ—.
汽車??萬(wàn)向 ?向機(jī)構(gòu)的 動(dòng)學(xué)設(shè)計(jì)與優(yōu)化[J].汽車技術(shù), 2012(1):40~44. [11] ?“, ,
保全. ???萬(wàn)向 ? 角優(yōu)化設(shè)計(jì)[J].汽車技術(shù), 2012(9):19~22. [12]?o ,許 ,
¥. CATIA V5機(jī)¢設(shè)計(jì)[M]. ?:機(jī)¢工業(yè)出 £,2001. [13] , “.a 式 機(jī)???式¨?
?有限元分析[J], a設(shè) , 2004:12~14. [14] , ˉ?,???. CATIA V5 R20高o
應(yīng)用[M]. ?:‰ 大學(xué)出 £,2011. [15] , 生.車 ?引裝置的 制[J].機(jī)¢工 師,
2002(4):34~35. [16]高 , . ANSYS 機(jī)¢工 應(yīng)用25 [M]. ?:電子工業(yè)出 £,
2007. [17] ?, . ANSYS ??? ?£的 [J]. 機(jī)¢,2005(06) .
畢 業(yè) 設(shè) 計(jì)(論文) 開 題 報(bào) 告
2. ?題要 或解?的?題 ? 用的 段( ):
一 ?題 以 車 基 為依據(jù)對(duì)其萬(wàn)向傳動(dòng)裝置進(jìn)??構(gòu)設(shè)計(jì),并進(jìn)?靜 作用下的扭??度分析。
并分析其 據(jù)?果,為傳動(dòng)裝置的優(yōu)化設(shè)計(jì) 。二 ?£ (1)查…萬(wàn)向傳動(dòng)裝置設(shè)計(jì)資料, 入
了解萬(wàn)向傳動(dòng)裝置。 (2)熟悉CATIA,Pro/E,ANSYS 。 (3)查… 期刊 論文了解o的設(shè)計(jì)
分析?£。 (4)遇到?題及時(shí)與指導(dǎo)老師交 fi教。
畢 業(yè) 設(shè) 計(jì)(論文) 開 題 報(bào) 告
指導(dǎo)教師意見:
1.對(duì)“文獻(xiàn)綜述”的評(píng) :
??專業(yè)特點(diǎn),針對(duì)?題所涉及 領(lǐng)域的文獻(xiàn)進(jìn)? ?…讀,且對(duì)文獻(xiàn)資料歸納及分析 較及 入理解,
并 對(duì)該領(lǐng)域的 現(xiàn)狀 動(dòng)態(tài)及發(fā)展?向 進(jìn)?綜?分析 評(píng)述, 出了自己的見解 思路及 ?題。
′較 順, 緊緊圍繞?題闡述, ?文獻(xiàn)綜述要求。
2.對(duì) ?題的 度 度及工作量的意見 對(duì)設(shè)計(jì)(論文)?果的預(yù)測(cè):
?題首 利用CATIA 對(duì)汽車萬(wàn)向傳動(dòng)裝置零 進(jìn)?? , 后對(duì)傳動(dòng)?進(jìn)?有限元分析, 度 度?
。所涉及 內(nèi)容必須要求在認(rèn)真學(xué)習(xí)了 專業(yè)? 以后,再經(jīng) 進(jìn)一 入學(xué)習(xí)有限元分析?£及
之后,才 做好 ?題的,工作量? 。該生經(jīng) 認(rèn)真充分地學(xué)習(xí) 準(zhǔn) 工作,應(yīng) 夠?期完成畢業(yè)設(shè)
計(jì)的。
3.ˉ否同意開題:√ 同意 □ 同意
指導(dǎo)教師:
2016 03 09
所在專業(yè)審查意見:
同意
負(fù)責(zé) :
2016 04 07
畢 業(yè) 設(shè) 計(jì)(論 文)外 文 參 考 資 料 及 譯 文
譯文題目: THE BRAKE BIBLE
制動(dòng)器
學(xué)生姓名:
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THE BRAKE BIBLE
Brakes - what do they do?
The simple answer: they slow you down.
The complex answer: brakes are designed to slow down your vehicle but probably not by the means that you think. The common misconception is that brakes squeeze against a drum or disc, and the pressure of the squeezing action is what slows you down. This in fact is only part of the equation. Brakes are essentially a mechanism to change energy types. When you're travelling at speed, your vehicle has kinetic energy. When you apply the brakes, the pads or shoes that press against the brake drum or rotor convert that energy into thermal energy via friction. The cooling of the brakes dissipates the heat and the vehicle slows down. It's the First Law of Thermodynamics, sometimes known as the law of conservation of energy. This states that energy cannot be created nor destroyed, it can only be converted from one form to another. In the case of brakes, it is converted from kinetic energy to thermal energy.
Angular force
Because of the configuration of the brake pads and rotor in a disc brake, the location of the point of contact where the friction is generated also provides a mechanical moment to resist the turning motion of the rotor.
Thermodynamics, brake fade and drilled rotors
If you ride a motorbike or drive a race car, you're probably familiar with the term brake fade, used to describe what happens to brakes when they get too hot. A good example is coming down a mountain pass using your brakes rather than your engine to slow you down. As you start to come down the pass, the brakes on your vehicle heat up, slowing you down. But if you keep using them, the rotors or drums stay hot and get no chance to cool off. At some point they can't absorb any more heat so the brake pads heat up instead. In every brake pad there is the friction material that is held together with some sort of resin and once this starts to get too hot, the resin starts to vapourise, forming a gas. Because the gas can't stay between the pad and the rotor, it forms a thin layer between the two whilst trying to escape. The pads lose contact with the rotor, reducing the amount of friction and voila. Complete brake fade.
The typical remedy for this would be to get the vehicle to a stop and wait for a few minutes. As the brake components cool down, their ability to absorb heat returns and the next time you use the brakes, they seem to work just fine. This type of brake fade was more common in older vehicles. Newer vehicles tend to have less outgassing from the brake pad compounds but they still suffer brake fade. So why? It's still to do with the pads getting too hot. With newer brake pad compounds, the pads transfer heat into the calipers once the rotors are too hot, and the brake fluid starts to boil forming bubbles in it. Because air is compressible (brake fluid isn't) when you step on the brakes, the air bubbles compress instead of the fluid transferring the motion to the brake calipers. Voila. Modern brake fade.
So how do the engineers design brakes to reduce or eliminate brake fade? For older vehicles, you give that vapourised gas somewhere to go. For newer vehicles, you find some way to cool the rotors off more effectively. Either way you end up with cross-drilled or grooved brake rotors. While grooving the surface may reduce the specific heat capacity of the rotor, its effect is negligible in the grand scheme of things. However, under heavy braking once everything is hot and the resin is vapourising, the grooves give the gas somewhere to go, so the pad can continue to contact the rotor, allowing you to stop.
The whole understanding of the conversion of energy is critical in understanding how and why brakes do what they do, and why they are designed the way they are. If you've ever watched Formula 1 racing, you'll see the front wheels have huge scoops inside the wheel pointing to the front (see the picture above). This is to duct air to the brake components to help them cool off because in F1 racing, the brakes are used viciously every few seconds and spend a lot of their time trying to stay hot. Without some form of cooling assistance, the brakes would be fine for the first few corners but then would fade and become near useless by half way around the track.
Rotor technology
If a brake rotor was a single cast chunk of steel, it would have terrible heat dissipation properties and leave nowhere for the vapourised gas to go. Because of this, brake rotors are typically modified with all manner of extra design features to help them cool down as quickly as possible as well as dissapate any gas from between the pads and rotors. The diagram here shows some examples of rotor types with the various modification that can be done to them to help them create more friction, disperse more heat more quickly, and ventilate gas. From left to right.
1: Basic brake rotor. 2: Grooved rotor - the grooves give more bite and thus more friction as they pass between the brake pads They also allow gas to vent from between the pads and the rotor. 3: Grooved, drilled rotor - the drilled holes again give more bite, but also allow air currents (eddies) to blow through the brake disc to assist cooling and ventilating gas. 4: Dual ventilated rotors - same as before but now with two rotors instead of one, and with vanes in between them to generate a vortex which will cool the rotors even further whilst trying to actually 'suck' any gas away from the pads.
An important note about drilled rotors: Drilled rotors are typically only found (and to be used on) race cars. The drilling weakens the rotors and typically results in microfractures to the rotor. On race cars this isn't a problem - the brakes are changed after each race or weekend. But on a road car, this can eventually lead to brake rotor failure - not what you want. I only mention this because of a lot of performance suppliers will supply you with drilled rotors for street cars without mentioning this little fact.
Big rotors
How does all this apply to bigger brake rotors - a common sports car upgrade? Sports cars and race bikes typically have much bigger discs or rotors than your average family car. A bigger rotor has more material in it so it can absorb more heat. More material also means a larger surface area for the pads to generate friction with, and better heat dissipation. Larger rotors also put the point of contact with the pads further away from the axle of rotation. This provides a larger mechanical advantage to resist the turning of the rotor itself. To best illustrate how this works, imagine a spinning steel disc on an axle in front of you. If you clamped your thumbs either side of the disc close to the middle, your thumbs would heat up very quickly and you'd need to push pretty hard to generate the friction required to slow the disc down. Now imagine doing the same thing but clamping your thumbs together close to the outer rim of the disc. The disc will stop spinning much more quickly and your thumbs won't get as hot. That, in a nutshell explains the whole principle behind why bigger rotors = better stopping power.
The different types of brake
All brakes work by friction. Friction causes heat which is part of the kinetic energy conversion process. How they create friction is down to the various designs.
Bicycle wheel brakes
I thought I'd cover these because they're about the most basic type of functioning brake that you can see, watch working, and understand. The construction is very simple and out-in-the-open. A pair of rubber blocks are attached to a pair of calipers which are pivoted on the frame. When you pull the brake cable, the pads are pressed against the side or inner edge of the bicycle wheel rim. The rubber creates friction, which creates heat, which is the transfer of kinetic energy that slows you down. There's only really two types of bicycle brake - those on which each brake shoe shares the same pivot point, and those with two pivot points. If you can look at a bicycle brake and not understand what's going on, the rest of this page is going to cause you a bit of a headache.
Drum brakes - single leading edge
The next, more complicated type of brake is a drum brake. The concept here is simple. Two semicircular brake shoes sit inside a spinning drum which is attached to the wheel. When you apply the brakes, the shoes are expanded outwards to press against the inside of the drum. This creates friction, which creates heat, which transfers kinetic energy, which slows you down. The example below shows a simple model. The actuator in this case is the blue elliptical object. As that is twisted, it forces against the brake shoes and in turn forces them to expand outwards. The return spring is what pulls the shoes back away from the surface of the brake drum when the brakes are released.
The "single leading edge" refers to the number of parts of the brake shoe which actually contact the spinning drum. Because the brake shoe pivots at one end, simple geometry means that the entire brake pad cannot contact the brake drum. The leading edge is the term given to the part of the brake pad which does contact the drum, and in the case of a single leading edge system, it's the part of the pad closest to the actuator. This diagram shows what happens as the brakes are applied. The shoes are pressed outwards and the part of the brake pad which first contacts the drum is the leading edge. The action of the drum spinning actually helps to draw the brake pad outwards because of friction, which causes the brakes to "bite". The trailing edge of the brake shoe makes virtually no contact with the drum at all. This simple geometry explains why it's really difficult to stop a vehicle rolling backwards if it's equipped only with single leading edge drum brakes. As the drum spins backwards, the leading edge of the shoe becomes the trailing edge and thus doesn't bite.
Drum brakes - double leading edge
The drawbacks of the single leading edge style of drum brake can be eliminated by adding a second return spring and turning the pivot point into a second actuator. Now when the brakes are applied, the shoes are pressed outwards at two points. So each brake pad now has one leading and one trailing edge. Because there are two brake shoes, there are two brake pads, which means there are two leading edges. Hence the name double leading edge.
Disc brakes Some background
Disc brakes were invented in 1902 and patented by Birmingham car maker Frederick William Lanchester. His original design had two discs which pressed against each other to generate friction and slow his car down. It wasn't until 1949 that disc brakes appeared on a production car though. The obscure American car builder Crosley made a vehicle called the Hotshot which used the more familiar brake rotor and calipers that we all know and love today. His original design was a bit crap though - the brakes lasted less than a year each. Finally in 1954 Citro?n launched the way-ahead-of-its-time DS which had the first modern incarnation of disc brakes along with other nifty stuff like self-levelling suspension, semi-automatic gearbox, active headlights and composite body panels. (all things which were re-introduced as "new" by car makers in the 90's).Disc brakes are an order of magnitude better at stopping vehicles than drum brakes, which is why you'll find disc brakes on the front of almost every car and motorbike built today. Sportier vehicles with higher speeds need better brakes to slow them down, so you'll likely see disc brakes on the rear of those too.
制動(dòng)器
制動(dòng)器:它們的作用?
簡(jiǎn)單的說(shuō):它會(huì)使你的汽車慢下來(lái)。
復(fù)雜的說(shuō):制動(dòng)器被用來(lái)讓你的車減速,但可能不是你所想的意思。普遍的誤解是,制動(dòng)器擠壓制動(dòng)鼓或制動(dòng)片,擠壓的壓力的作用使你的車慢下來(lái)。但這只是制動(dòng)的一部分。制動(dòng)系統(tǒng)本質(zhì)上是改變能量的類型。當(dāng)你在全速行駛時(shí),你的汽車獲得動(dòng)能。當(dāng)你踩下剎車,墊子或鞋子對(duì)制動(dòng)鼓和轉(zhuǎn)子的作用轉(zhuǎn)化為摩擦熱能。剎車的冷卻使車的熱能消散,減慢車速。這是熱力學(xué)第一定律,有時(shí)被視為能量守恒定律。也是就說(shuō):能量不能被創(chuàng)造也不能被消滅,只能由一種形式轉(zhuǎn)換成另一種。制動(dòng)情況下,它是動(dòng)能轉(zhuǎn)化為熱能。
角向力
因?yàn)樵诒P式制動(dòng)器的剎車片和轉(zhuǎn)子的位置,摩擦產(chǎn)生的接觸點(diǎn)的位置也產(chǎn)生了一個(gè)機(jī)械的抵御轉(zhuǎn)子的回轉(zhuǎn)運(yùn)動(dòng)。
熱力學(xué),制動(dòng)失效,鉆孔轉(zhuǎn)子
如果你騎摩托車或駕駛一輛賽車,你或許熟悉制動(dòng)失效,描述當(dāng)制動(dòng)器太熱,他發(fā)生了什么。一個(gè)很好的例子就是從山上下來(lái)使用剎車制動(dòng),而不是你的引擎使你減速。當(dāng)汽車開始滑動(dòng)下來(lái)時(shí),剎車使汽車產(chǎn)生熱能,使你減速。但是如果你持續(xù)使用他們, 轉(zhuǎn)子或鼓留熱并沒有機(jī)會(huì)冷卻。從某種意義上說(shuō)他們不能吸收更多的熱量,使剎車墊熱了起來(lái)。在每一個(gè)墊子的摩擦材料有某種共同的樹脂。一旦開始變得太熱,該樹脂開始蒸發(fā),形成氣。由于氣體不能待在墊層和轉(zhuǎn)子之中,而是形成薄薄的一層在兩個(gè)之間準(zhǔn)備排走。墊子失去與轉(zhuǎn)子的接觸,減少摩擦和熱量。這是完全的制動(dòng)失效。
典型的補(bǔ)救辦法,將車停了下來(lái),等待幾分鐘。由于制動(dòng)部件降溫,吸收熱量的原因,下一次您使用剎車的能力,似乎會(huì)好一點(diǎn)。這種類型的制動(dòng)失效在舊車輛更常見。新的車輛往往從剎車墊中減少排氣,但他們?nèi)杂兄苿?dòng)失效。為什么呢?它仍然因?yàn)閯x車墊太熱。由于新的剎車墊合成,襯墊的熱傳遞到卡鉗,一旦轉(zhuǎn)子太熱了,制動(dòng)液開始沸騰冒泡。因?yàn)榭諝馐强蓧嚎s的(制動(dòng)液不是)當(dāng)你踩剎車,氣泡的壓縮代替了流體轉(zhuǎn)移到制動(dòng)卡鉗。這就是現(xiàn)代制動(dòng)失效。
工程師們是怎樣設(shè)計(jì)來(lái)減少或消除剎車制動(dòng)失效的? 年久的車輛,是使氣化的氣體有地方排掉。新的車輛,找到一些方式來(lái)冷卻轉(zhuǎn)子更為有效。無(wú)論如何你最終獲得交叉鉆孔或溝槽剎車盤。當(dāng)槽表面是可以減少比熱容量的轉(zhuǎn)子,其效果可以忽略不計(jì)的。然而當(dāng)大力剎車時(shí)一旦一切都是熱和樹脂材料蒸發(fā),槽讓氣體排去, 所以墊可以繼續(xù)接觸轉(zhuǎn)子,讓車減速停下來(lái)。
整個(gè)的理解能量轉(zhuǎn)換的關(guān)鍵是,剎車它們?cè)撟鍪裁?以及為什么它們?cè)O(shè)計(jì)成這樣。如果你曾看過(guò)一級(jí)方程式賽車,你就可以看到向前的前輪里面有很大的洞。這是管道空氣剎車部件,以幫助他們冷卻下來(lái),因?yàn)樵贔1賽車中,剎車每隔幾秒鐘頻繁使用,花很多時(shí)間預(yù)留熱量。如果沒有某種冷卻協(xié)助,剎車就可能在最開始的幾個(gè)轉(zhuǎn)角失靈,最后剎車失效,賽車在一半路程出局。
轉(zhuǎn)子技術(shù)
如果制動(dòng)轉(zhuǎn)子是一個(gè)單一的鋼鐵鑄塊,散熱性能將會(huì)很差并且氣化氣無(wú)法排去。因此,剎車盤通常使用具有各種額外的設(shè)計(jì)特點(diǎn)的方式來(lái)幫助他們冷卻下來(lái),盡快使墊和轉(zhuǎn)子之間的任何氣體排走。 這里顯示了轉(zhuǎn)子類型的各種修改,可以改進(jìn)幫助他們創(chuàng)造更多的摩擦力,更迅速地驅(qū)散更多的熱量,通風(fēng)氣體的一些例子。 從左至右
1:基本制動(dòng)轉(zhuǎn)子。2:溝槽轉(zhuǎn)子-溝槽給予更多口,他們之間產(chǎn)生更多的摩擦,還允許氣體從墊和轉(zhuǎn)子之間的排走。3:溝槽鉆孔轉(zhuǎn)子-再給多一點(diǎn)口,但也讓氣流(渦旋)通過(guò)制動(dòng)盤來(lái)協(xié)助冷卻和通風(fēng)。4:雙通風(fēng)轉(zhuǎn)子-與以前一樣,但現(xiàn)在有了兩個(gè)轉(zhuǎn)子而不是一個(gè),他們之間的葉片產(chǎn)生的渦流將進(jìn)一步冷卻轉(zhuǎn)子同時(shí)試著從襯墊中排掉任意氣體。
重要的一點(diǎn):鉆孔轉(zhuǎn)子通常只使用于賽車。鉆孔使得轉(zhuǎn)子變?nèi)?,通常?huì)導(dǎo)致轉(zhuǎn)子產(chǎn)生各類裂縫。但在賽車中這不是一個(gè)問(wèn)題——在每場(chǎng)比賽或者每周都會(huì)更換剎車盤。但在路上的車,這最終會(huì)導(dǎo)致剎車轉(zhuǎn)子失靈,不是你能想象的。我提這件事是因?yàn)橛性S多供應(yīng)商將為您提供鉆孔轉(zhuǎn)子,沒有直接提到這個(gè)事實(shí)。
大轉(zhuǎn)子
這是如何適用于更大的剎車轉(zhuǎn)子-一種普遍的跑車升級(jí)?汽車和自行車運(yùn)動(dòng)比賽通常有比一般的家庭汽車更大的轉(zhuǎn)子。一個(gè)更大的轉(zhuǎn)子有更多的材料在里面,因此它可以吸收更多的熱量。更多的物質(zhì)也意味著更大的表面積,墊片產(chǎn)生摩擦,更好的散熱。較大的角度也將轉(zhuǎn)子接觸墊進(jìn)一步遠(yuǎn)離軸旋轉(zhuǎn)。這提供了一個(gè)更大的機(jī)械優(yōu)勢(shì)抵抗旋轉(zhuǎn)的轉(zhuǎn)子本身。這個(gè)工作最好的說(shuō)明,設(shè)想一種紡紗鋼軸上的閥瓣在你的面前。如果你夾緊你的大拇指向任何一方的閥瓣靠近中間,你的大拇指將熱得非??欤銜?huì)需要相當(dāng)大的摩擦力推動(dòng)來(lái)使閥瓣慢下來(lái)?,F(xiàn)在想象做同樣的事情,但是你的大拇指夾在一起接近外緣的閥瓣。閥瓣將停止旋轉(zhuǎn)得特別快,你的大拇指也不會(huì)很熱。簡(jiǎn)單地說(shuō)解釋整個(gè)原理就是更大轉(zhuǎn)子=更好的制動(dòng)原則。
不同類型的制動(dòng)器
所有制動(dòng)器都產(chǎn)生摩擦力。Friction causes heat which is part of the kinetic energy conversion process.
摩擦引起的熱量,這是動(dòng)能轉(zhuǎn)換過(guò)程的一部分。他們?nèi)绾蝿?chuàng)造摩擦是下降到各種設(shè)計(jì)。
自行車車輪制動(dòng)器
我想我會(huì)掩蓋這些,因?yàn)樗鼈兪亲罨绢愋偷闹苿?dòng)方式,你可以看到,觀察工作并了解到。設(shè)計(jì)非常簡(jiǎn)單,在外部。一雙橡膠塊連接到一雙卡鉗,能在機(jī)架上旋轉(zhuǎn)。當(dāng)你拉剎車線,剎車墊壓向一側(cè)或自行車輪輞的內(nèi)側(cè)邊緣。 橡膠產(chǎn)生摩擦,產(chǎn)生熱量,這時(shí)動(dòng)能轉(zhuǎn)移使車慢下來(lái)。 自行車制動(dòng)實(shí)際上只有兩個(gè)類型 - 自行車剎車制動(dòng)蹄上有相同的摩擦點(diǎn),并有兩個(gè)摩擦點(diǎn)。 如果你看了自行車制動(dòng),不明白是什么原理,本頁(yè)面的其余部分你理解起來(lái)有麻煩了。
鼓式制動(dòng)器-單前沿
下一個(gè)更加復(fù)雜的類型的制動(dòng)是鼓式制動(dòng)器。這里的概念很簡(jiǎn)單。兩個(gè)半圓形的剎車片裝在制動(dòng)器里并連接一個(gè)旋轉(zhuǎn)的車輪鼓。當(dāng)你踩下剎車,剎車片向外擴(kuò)大擠壓內(nèi)側(cè)的鼓。這造成了摩擦,產(chǎn)生熱量,轉(zhuǎn)移動(dòng)能,這將使車減速。下面的例子顯示了一個(gè)簡(jiǎn)單的模型。這種情況下制動(dòng)器是藍(lán)色的橢圓形物體。因?yàn)槭桥で?,它的力使剎車片反過(guò)來(lái)迫使他們向外擴(kuò)張。當(dāng)松開剎車,回位彈簧從制動(dòng)鼓的表面拉回剎車片。
"單前沿"是指實(shí)際接觸的旋轉(zhuǎn)鼓輪制動(dòng)蹄部件的數(shù)量。因?yàn)橹苿?dòng)蹄片在一端,簡(jiǎn)單的幾何意味著整個(gè)剎車片無(wú)法都接觸到制動(dòng)鼓。前緣是指部分剎車片接觸鼓,和一個(gè)前沿系統(tǒng)的情況下,它是墊最接近致動(dòng)器的一部分。此圖顯示當(dāng)剎車應(yīng)用時(shí)將會(huì)發(fā)生什么情況。剎車片向外壓和制動(dòng)襯墊的最初接觸制動(dòng)鼓的部分剎車片就是前沿。制動(dòng)鼓旋轉(zhuǎn)實(shí)際上有助于制動(dòng)片向外加壓,這是因?yàn)閯x車片向口子的摩擦力。后沿的制動(dòng)蹄片與制動(dòng)鼓幾乎沒有接觸。這個(gè)簡(jiǎn)單的幾何解釋了,為什么汽車是很難停止向后滾動(dòng),如果它只配單前緣沿鼓式制動(dòng)器。由于制動(dòng)鼓向后旋轉(zhuǎn),前沿的剎車片成為了后沿,因此制動(dòng)不會(huì)咬合。
鼓剎車-雙前沿
可以通過(guò)添加回位彈簧和旋轉(zhuǎn)第二個(gè)制動(dòng)器中心點(diǎn)來(lái)消除鼓式制動(dòng)器的單個(gè)前沿的缺點(diǎn)。踩下剎車時(shí),剎車片在兩個(gè)點(diǎn)向外壓。所以每個(gè)剎車片現(xiàn)在有一個(gè)前沿的和一個(gè)后沿。因?yàn)橛袃蓚€(gè)剎車蹄,那里有兩個(gè)剎車片,這意味著有兩個(gè)邊沿。因此名稱雙前沿。
盤式制動(dòng)器一些背景
盤式制動(dòng)器在 1902 年被發(fā)明,它是伯明翰汽車制造商檢基威廉 · 蘭徹斯特的專利。他原先設(shè)計(jì)了兩個(gè)光盤,緊貼彼此產(chǎn)生摩擦來(lái)使車減速。直到 1949 盤式制動(dòng)器在量產(chǎn)車上的使用。美國(guó)汽車創(chuàng)始人克羅斯利發(fā)明了我們目前熟知和喜愛的快車,它就是使用了很多類似的盤式制動(dòng)器和卡鉗。他原先的設(shè)計(jì)有點(diǎn)缺陷-制動(dòng)器使用持續(xù)不到一年。終于在 1954 年雪鐵龍推出先進(jìn)的DS,成就了自流平懸浮、半自動(dòng)變速箱、活動(dòng)前燈和復(fù)合車身盤式制動(dòng)器的第一次現(xiàn)代化身。(所有事情,在 90 年代的汽車制造商都重新作為"新型")。盤式制動(dòng)器比鼓式制動(dòng)器好了一個(gè)數(shù)量級(jí)來(lái)使車輛制動(dòng),這就是為什么你會(huì)發(fā)現(xiàn)的現(xiàn)代幾乎所以汽車和摩托車都使用的是盤式制動(dòng)器。運(yùn)動(dòng)型車輛具有更高的速度,所以需要更好的制動(dòng)減速,因此您會(huì)明白盤式制動(dòng)器在這些車上的使用。
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