本文選題：柴油機(jī) + 氣缸蓋��； 參考：《大連理工大學(xué)》2015年碩士論文

【摘要】：氣缸蓋是內(nèi)燃機(jī)動(dòng)力組裝配中最為重要和復(fù)雜的部件之一,也是內(nèi)燃機(jī)工作環(huán)境最惡劣的部件。在柴油機(jī)工作過程中,氣缸蓋火焰面需要承受缸內(nèi)燃料燃燒產(chǎn)生的高溫,同時(shí),氣缸蓋還要承受巨大的缸內(nèi)爆發(fā)壓力。高溫產(chǎn)生的熱應(yīng)力、缸內(nèi)爆發(fā)壓力、螺栓預(yù)緊力、氣門座過盈力等同時(shí)作用在氣缸蓋上,使得氣缸蓋的工作環(huán)境十分復(fù)雜,大大增加了對(duì)氣缸蓋分析的難度。本文是對(duì)某八缸中速柴油機(jī)氣缸蓋進(jìn)行有限元耦合分析,主要包括三個(gè)部分,第一部分是求解氣缸蓋溫度場(chǎng)和熱應(yīng)力,首先,運(yùn)用Pro/E軟件建立柴油機(jī)氣缸蓋的三維實(shí)體模型,然后將模型導(dǎo)入有限元軟件ANSYS workbench進(jìn)行網(wǎng)格劃分和熱邊界條件的設(shè)置,最后計(jì)算氣缸蓋的溫度分布,把計(jì)算結(jié)果與實(shí)際測(cè)點(diǎn)溫度進(jìn)行對(duì)比,二者在誤差范圍內(nèi)吻合。第二部分是對(duì)氣缸蓋進(jìn)行熱與機(jī)械強(qiáng)度的耦合分析,首先設(shè)置氣缸蓋的約束和力邊界條件,計(jì)算機(jī)械應(yīng)力對(duì)氣缸蓋的影響,然后把熱與機(jī)械強(qiáng)度進(jìn)行耦合計(jì)算,得到氣缸蓋的總的等效應(yīng)力分布情況。最后把熱應(yīng)力云圖、機(jī)械應(yīng)力云圖、總耦合應(yīng)力云圖進(jìn)行對(duì)比和分析。第三部分我嘗試對(duì)氣缸蓋結(jié)構(gòu)做了一些改進(jìn),主要改變的區(qū)域是鼻梁區(qū)。計(jì)算結(jié)果表明氣缸蓋溫度較高的位置主要是在氣缸蓋火力面兩個(gè)排氣道之間的鼻梁區(qū)域,同時(shí)排氣道表面的溫度整體較高。氣缸蓋耦合總等效應(yīng)力較高的位置出現(xiàn)在進(jìn)、排氣門之間的兩處鼻梁區(qū),偏向于排氣門一側(cè)。把熱應(yīng)力分布圖、機(jī)械應(yīng)力分布圖和耦合場(chǎng)應(yīng)力分布圖對(duì)比可以發(fā)現(xiàn)熱應(yīng)力對(duì)氣缸蓋整體受力分布的影響最大。耦合之后的應(yīng)力并不是簡單把熱應(yīng)力和機(jī)械應(yīng)力相互疊加。由于該八缸柴油機(jī)處于研發(fā)設(shè)計(jì)階段,本文的工作可以為氣缸蓋結(jié)構(gòu)的設(shè)計(jì)和改進(jìn)提供必要參考。
[Abstract]:Cylinder head is one of the most important and complex parts in the assembly of engine power group, and it is also the worst part in internal combustion engine working environment.In the working process of diesel engine, the flame surface of cylinder head has to bear the high temperature produced by the combustion of fuel in cylinder, and the cylinder head has to bear the huge burst pressure in cylinder at the same time.The thermal stress produced by high temperature, the burst pressure in the cylinder, the pretightening force of the bolt and the interference force of the valve seat act on the cylinder head at the same time, which makes the working environment of the cylinder head very complex, which greatly increases the difficulty of analyzing the cylinder head.In this paper, the finite element coupling analysis of the cylinder head of an eight-cylinder medium speed diesel engine is carried out, which mainly includes three parts. The first part is to solve the temperature field and thermal stress of the cylinder head. Firstly, the three-dimensional solid model of the cylinder head of the diesel engine is established by using Pro/E software.Then the model is imported into the finite element software ANSYS workbench to divide the mesh and set the thermal boundary conditions. Finally, the temperature distribution of the cylinder head is calculated, and the calculated results are compared with the actual measured point temperature. The results are in good agreement with each other in the error range.The second part is the coupling analysis of thermal and mechanical strength of cylinder head. Firstly, the constraint and force boundary conditions of cylinder head are set, the influence of mechanical stress on cylinder head is calculated, and the coupling calculation of heat and mechanical strength is carried out.The total equivalent stress distribution of the cylinder head is obtained.Finally, the thermal stress cloud, mechanical stress cloud and total coupled stress cloud are compared and analyzed.In the third part, I try to improve the cylinder head structure.The results show that the high temperature of cylinder head is mainly located in the nose beam area between two exhaust channels on the cylinder head fire surface, and the temperature of the exhaust duct surface is higher as a whole.The high position of the coupled total equivalent stress of cylinder head appears in the two areas of nose beam between the inlet and the exhaust valve, which is inclined to the side of the exhaust valve.By comparing the thermal stress distribution, mechanical stress distribution and coupled field stress distribution, it is found that the thermal stress has the greatest influence on the overall stress distribution of the cylinder head.The coupled stress is not simply a superposition of the thermal stress and the mechanical stress.Because the eight cylinder diesel engine is in the stage of R & D, the work in this paper can provide the necessary reference for the design and improvement of cylinder head structure.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TK423

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本文編號(hào)：1767348