本文關(guān)鍵詞： 交叉變輪距 轉(zhuǎn)向單元 優(yōu)化設(shè)計 有限元 虛擬樣機(jī)　出處：《青島理工大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：常見車輛一般為定輪距結(jié)構(gòu),而對于農(nóng)用車輛來說,輪距可調(diào)能夠擴(kuò)大作業(yè)對象范圍,大大提升利用效率。目前,國內(nèi)可調(diào)輪距的車輛一般是人工有級調(diào)節(jié)的,在無級變輪距技術(shù)領(lǐng)域的研究較少;而國外很多農(nóng)用車輛已應(yīng)用變輪距技術(shù),如自走式噴藥機(jī)系列,這些車輛一般自動化程度較高,價格昂貴,且使用和維修比較復(fù)雜,因此,在國內(nèi)推廣應(yīng)用受到極大限制。通過對變輪距技術(shù)的相關(guān)研究,提出了一種“交叉變輪距”技術(shù),即將傳統(tǒng)前后平行式車橋改為交叉布置,通過改變車橋間夾角來間接實現(xiàn)輪距的無級調(diào)節(jié)。由于車輛轉(zhuǎn)向性能的優(yōu)劣是評價作業(yè)質(zhì)量高低的一個重要標(biāo)準(zhǔn),故對交叉變輪距底盤轉(zhuǎn)向機(jī)構(gòu)的運(yùn)動學(xué)研究是十分必要且極具價值的。首先,研究了交叉變輪距底盤轉(zhuǎn)向原理。根據(jù)交叉變輪距底盤輪距無級可變的特點,將傳統(tǒng)的定參數(shù)轉(zhuǎn)向機(jī)構(gòu)改為參數(shù)可變的“轉(zhuǎn)向單元”,使轉(zhuǎn)向特性能夠隨著輪距的改變而變化,從而保證車輛的正常轉(zhuǎn)向。對轉(zhuǎn)向單元進(jìn)行優(yōu)化設(shè)計,應(yīng)用機(jī)構(gòu)學(xué)相關(guān)理論,對轉(zhuǎn)向單元建立平面幾何模型,根據(jù)阿克曼轉(zhuǎn)向原理推導(dǎo)出交叉變輪距車輛理想轉(zhuǎn)向內(nèi)外輪轉(zhuǎn)角關(guān)系;利用平面幾何模型求解出實際內(nèi)外輪轉(zhuǎn)角關(guān)系。建立轉(zhuǎn)向單元的多參數(shù)優(yōu)化目標(biāo)函數(shù),確定相關(guān)約束條件,借助Matlab軟件對轉(zhuǎn)向單元進(jìn)行優(yōu)化設(shè)計。其次,對轉(zhuǎn)向橫拉桿的強(qiáng)度和穩(wěn)定性校核。轉(zhuǎn)向橫拉桿是決定轉(zhuǎn)向單元能否正常工作的關(guān)鍵部件,在Ansys中對轉(zhuǎn)向橫拉桿進(jìn)行有限元分析,觀察其應(yīng)力分布及變形情況,確保能夠滿足強(qiáng)度和穩(wěn)定性的要求。最后,結(jié)合整車結(jié)構(gòu)的設(shè)計參數(shù),在Adams中建立虛擬樣機(jī)模型,對交叉變輪距車輛的轉(zhuǎn)向特性進(jìn)行運(yùn)動學(xué)研究。通過運(yùn)動仿真得到實際內(nèi)外輪轉(zhuǎn)角變化曲線,再對比分析阿克曼理想轉(zhuǎn)角變化曲線,驗證建模、仿真及優(yōu)化設(shè)計結(jié)果的準(zhǔn)確性。
[Abstract]:Common vehicles are usually fixed wheel spacing structure, but for agricultural vehicles, the adjustable wheel spacing can expand the scope of operation objects, greatly improve the utilization efficiency. At present, domestic adjustable wheel distance vehicles are generally manually adjusted. The research in the field of stepless wheel spacing technology is less; Many foreign agricultural vehicles have applied variable wheel distance technology, such as self-propelled spraying machine series, these vehicles are generally high degree of automation, expensive, and the use and maintenance of more complex, so. Through the research on the technology of variable wheel distance, a kind of "cross variable wheel distance" technology is put forward, that is, the traditional front and rear parallel vehicle bridge is changed to cross arrangement. The stepless adjustment of wheel distance is realized indirectly by changing the angle between the vehicle and the axle. The steering performance of the vehicle is an important criterion to evaluate the operation quality. Therefore, it is necessary and valuable to study the kinematics of cross-variable wheel pitch chassis steering mechanism. Firstly, the principle of cross-variable wheel pitch chassis steering is studied. By changing the traditional fixed parameter steering mechanism into a variable parameter steering unit, the steering characteristics can change with the change of wheel spacing, thus ensuring the normal steering of the vehicle and optimizing the design of the steering unit. Based on the theory of mechanism, the plane geometry model of steering unit is established, and the ideal steering angle of cross variable wheel distance vehicle is deduced according to Ackermann steering principle. Using the plane geometry model to solve the actual internal and external wheel rotation angle, the multi-parameter optimization objective function of steering unit is established, and the relative constraint conditions are determined. The Matlab software is used to optimize the design of steering unit. Secondly, the strength and stability of steering bar are checked. The steering rod is the key component to determine whether the steering unit can work properly. Finite element analysis of steering bar is carried out in Ansys to observe its stress distribution and deformation to ensure that it can meet the requirements of strength and stability. Finally, combined with the design parameters of the whole vehicle structure. A virtual prototype model is established in Adams to study the steering characteristics of cross-wheeled vehicles. The actual curves of internal and external wheel angle change are obtained by motion simulation. The accuracy of modeling, simulation and optimization design is verified by comparing and analyzing Ackerman's ideal angle curve.
【學(xué)位授予單位】：青島理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：U463.4

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