車輛專業課程設計說明
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- 車輛專業課程設計說明目錄
1.概述···············································································1
1.1 整車總布置設計的任務··························································2
1.2 設計原則、目標································································2
1.3設計方案的擬定································································2
2.整車型式的選擇·····································································3
2.1汽車軸數和驅動形式····························································3
2.2發動機的種類和型式····························································3
2.3車頭、駕駛室的型式····························································4
2.4輪胎的選擇····································································4
3.汽車主要參數的選擇·································································5
3.1主要尺寸參數的選擇····························································5
3.1.1軸距L···································································5
3.1.2前輪距B1和后輪距B2····················································5
3.1.3汽車的外廓尺寸···························································6
3.1.4前懸和后懸·························································6
3.2整車質量參數估算······························································7
3.2.1空車狀態下整車質量·······················································7
3.2.2汽車的軸荷分配···························································7
3.3主要性能參數的選擇····························································7
3.3.1動力性參數······························································9
3.3.2燃料經濟性參數··························································10
3.3.3機動性參數······························································10
3.3.4汽車的操縱穩定性參數····················································11
3.3.5行駛平順性參數··························································11
3.3.6制動性參數······························································12
3.3.7通過性參數·····························································12
4.發動機選型········································································14
4.1 發動機最大功率及其相應轉速···········································14
4.2 發動機最大轉矩及其相應轉速··········································15
4.3 發動機適應性系數φ···························································16
5.輪胎的選擇········································································17
6.汽車總布置圖的繪制································································18
6.1 搜集和繪制有關總成、部件的外形圖··············································18
6.2 基準線的選擇及其畫法·························································18
6.3 車廂及駕駛室的布置···························································19
6.4 發動機與離合器及變速器的布置·················································20
6.5 轉向系、操縱踏板及儀表板的布置················································20
6.6 車身底板的布置·······························································21
6.7 前后懸架的布置·······························································21
6.8 制動系的布置·································································21
6.9 油箱、備胎和行李箱等的布置····················································22
6.10軸荷分配和質心位置的計算····················································22
7.設計小結··········································································23
參考文獻·········································································24
汽車總體設計
1.概述
汽車設計的內容包括整車總體設計、總成設計和零件設計。整車總體設計又稱為汽車的總布置設計，其任務是使所設計的產品達到設計任務書所規定的整車參數和性能指標的要求，并將這些整車參數和性能指標分解為有關總成的參數和功能。解決人車之間的聯系問題屬于人機工程設計，它在汽車設計工作中占有極重要的位置。例如：駕駛操作空間尺寸的布置，車內乘客空間尺寸的布置，座椅尺寸參數與特性參數的選擇，車身的外觀造型與色彩，儀表板的造型及儀表的選型與布置，車身內飾材料與色彩的選擇，汽車的駕駛視野，汽車的駕駛性能與乘坐性能等，這些與人的感覺與視覺有直接聯系的方方面面，都會對汽車產品的設計質量、品位和市場競爭力產生巨大的影響。
汽車是一個系統，這是基于汽車只有如下屬性而具備組成系統的條件：
(1)汽車是由多個要素（子系統及連接零件）組成的整體，每個要素對整體的行為有影響；
(2)組成汽車的各要素對整體行為的影響不是獨立的；
(3)汽車的行為不是組成它的任何要素所能具有的。
由此，汽車具備系統的屬性，對環境表現出整體性、一輛子系統屬性匹配協調的汽車所具備的功能大于組成它的各子系統功能純粹的、簡單的總和、反之，如果子系統的屬性因無序而相互干擾，即便是個體性能優良的子系統，其功能也會因相互扼制而抵消，功率循環、軸轉向等就是這樣的典型例子。
系統論所揭示的系統整體性和系統功能的等級性必然會映射到設計任務中來、用整體性來解釋汽車設計的終極目標是整車性能的綜合優化，道理是十分顯然的、汽車設計任務的等級形態表現為：上位設計任務是確定下位設計任務要實現的目標，下位設計是實現上位設計功能的手段、上、下位體系可從總體設計逐級分至零件設計，總體設計無疑處于這種體系的最上位，設計子系統的全部活動必須在總體設計構建的框架內進行、子系統設計固然重要，但統攬全局、設計子系統組合和相互作用體系規則的總體設計對汽車的性能和質量的影響更加廣泛、更為深刻。
1.1 整車總布置設計的任務
(1) 從技術先進性、生產合理性和使用要求出發，正確選擇性能指標、質量和主要尺寸參數，提出總體設計方案，為各部件設計提供整車參數和設計要求；
(2) 對各部件進行合理布置和運動校核；
(3) 對整車性能進行計算和控制，保證汽車主要性能指標實現；
(4) 協調好整車與總成之間的匹配關系，配合總成完成布置設計，使整車的性能、可靠性達到設計要求。
1.2 設計原則、目標
(1)汽車的選型應根據汽車型譜、市場需求、產品的技術發展趨勢和企業的產品發展規劃進行；
(2)選型應在對同類型產品進行深入的市場調查、使用調查、生產工藝調查、樣車結構分析與性能分析及全面的技術、進行分析的基礎上進行；
(3)應從已有的基礎出發，對原有車型和引進的樣車進行分析比較，繼承優點，消除缺陷，采用已有且成熟可靠的先進技術與結構，開發新車型；
(4)涉及應遵守有關標準、規范、法規、法律，不得侵犯他人專利；
(5)力求零件標準化、部件通用化、產品系列化。
1.3設計方案的擬定
(1)調查研究與初始決策：選定設計目標，并制定產品設計工作及方針原則；
(2)總體方案設計：根據所選定的目標及對開發目標制定的工作方針、設計原則等主導思想提出整車設想；
(3)繪制總布置草圖，確定整車主要尺寸、質量參數與性能以及各總成的基本形式；
(4)編寫設計任務書；
(5)汽車總布置設計；
(6)總成設計。
2. 整車型式的選擇
根據設計原則，目標和用戶的需求特點，整車設計人員要提出被開發車型的整車型式方案，主要包括以下幾部分：
(1)發動機的種類和型式；
(2)軸數和驅動型式；
(3)車頭和駕駛室的型式及與發動機、前軸(輪)的位置關系；
(4)輪胎的選擇。
2.1汽車軸數和驅動形式
不同類型的汽車有不同的軸數和驅動型式，這主要根據使用條件、用途、工廠的生產條件、制造成本及公路的軸荷限值等因素進行選擇。汽車可以有兩軸、三軸、四軸甚至更多的軸數。影響選取軸數的因素主要有汽車的總質量、道路法規對軸載質量的限制和輪胎的負荷能力以及汽車的結構等。最常用的是兩軸、后驅動4×2式汽車，其中轎車還可以采用4×2前驅動式結構。對于一般總重小于 19t的汽車，都采用4×2后驅動的布置型式，因為這種汽車結構簡單、布置合理、機動性好、成本低、適合于公路使用，是—種典型的、成熟的結構型式。
2.2發動機的種類和型式
至今世界上絕大多數的汽車都是采用往復活塞式內燃機，其中絕大多數的轎車采用汽油機。根據發動機氣缸排列形式不同，發動機有直列、水平對置和V型三種。氣缸直列式排列具有結構簡單、寬度窄、布置方便等優點。但當發動機缸數多時，長度尺寸過長，在汽車上布置困難，因此直列式適用于6缸以下的發動機。此外，直列式還有高度尺寸大的缺點。
根據發動機冷卻方式不同，發動機分為水冷與風冷兩種。大部分汽車用水冷發動機，因為它具有冷卻均勻可靠、散熱良好、噪聲小和能解決車內供暖問題，以及加大散熱器面積后，能較好適應發動機增壓后散熱的需要等優點。水冷發動機的主要缺點是冷卻系結構復雜；使用與維修不方便；冷卻性能受環境溫度影響較大。選取發動機的冷卻方式為水冷。
2.3車頭、駕駛室的型式
車頭、駕駛室的型式是汽車的最主要的型式之一。其選擇主要決定于用戶的要求、安全性、維修保養的方便性和生產條件等因素。
2.4輪胎的選擇
輪胎的尺寸和型號是進行汽車性能計算和繪制總布置圖的重要原始數據之一，選擇的依據是車型、使用條件、輪胎的靜負荷、輪胎的額定負荷以及汽車的行駛速度。當然還應考慮與動力—傳動系參數的匹配以及對整車尺寸參數(例如汽車的最小離地間隙、總高等)的影響。...
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