車輛工程汽車離合器的外文文獻(xiàn)翻譯

1、湖 北 文 理 學(xué) 院畢業(yè)設(shè)計(論文)英文翻譯題 目 有限元熱分析的陶瓷離合器專 業(yè)車輛工程班 級xxx姓 名xxxx學(xué) 號2010138xx指導(dǎo)教師職 稱xxx 副教授2014年2月25日fethermal analysis of a ceramic clutch1. introductionabrasive dry running vehicle clutches are force closure couplings. torque and speed transmission are ensured by the frictional force generated between t

2、wo pressed surfaces. reasons for the application of ceramic as a friction medium include good heat and wear resistance properties, which provide the opportunity to drive higher pressures, and a low density. thus, an increasing power density is enabled with a parallel minimization of construction spa

3、ce.measurements with a first prototype of a clutch disk using ceramic facings were performed at karlsruhe university in a laboratory specialized in passenger car drive system testing. in the course of analysis the finite element (fe) model was to be constructed with the knowledge of measurement data

4、 and measurement conditions. calculations were intended to determine the temperature distribution of the clutch disk and its environment at each moment in time corresponding to measurements. it is essential to be familiar with the temperature range in order to examine the wear characteristics of the

5、 system. thus, important information is derived from measurement data. in critical load cases, the highest expected temperatures must be forecast in space and time in order to protect measuring instruments close to the location of heat generation.the goal of this study is to analyze and modify the c

6、lutch system to provide better operating conditions by improving the heat conduction and convection of the system or to increase the amount of the energy converted into frictional heat. furthermore, it is desired to find better design solutions for more efficient clutch systems.calculations were per

7、formed by the cosmos design star software. during model development, great care had to be taken for proper simplification of geometry, the selection of element sizes, and the correct adjustment of time steps due to the substantial hardware requirements for transient calculations. changes in thermal

8、parameters such as the surface heat convection coefficient and thermal load had to be taken into consideration on an on-going basis in terms of time and location. the two sides of the analyzed test clutch system can only be managed by two independent models linked by heat partition, according to the

9、 hypothesis that the contact temperature must be identical on both sides while there is proper contact between them and its value must be adjusted by iteration. calculations revealed that the heat partition changed by cycle and it differed along the inner and outer contact rings. as a result of the

10、different cooling characteristics between the ceramic and steel side, a heat ow is launched from the ceramic side to the steel side. this heat flow was also determined by iteration, its value also changes by cycle and differs along the inner and outer contact rings.2. first prototype of a clutch usi

11、ng engineering ceramics as friction material the examined clutch disk was developed according to the “specific ceramic” product development process established at the institute for product development (ipek) at the university of karlsruhe. this development process already has the possibility for con

12、nection to a real transmission shaft; further, it has a cushion spring device for the facings allowing good start behaviour. abrasive clutches must comply with the following basic requirements:l high torque transmission according to high friction coefficients,l high comfort (no vibrations through se

13、lf-induced chattering),l homogeneous temperature distribution,l low wear characteristic.a critical element of the switch is the abrasive disk.with regard to the design utmost care must be taken to select the right material. a high and constant friction coefficient,，wear resistance and thermal resist

14、ance are desired characteristics. the clutch disk has instead of the generally applied ring-shaped abrasive inlet two rows of ssic (as sintered) ceramic pellets. these pellets are placed on 6 separate segments. the segments are xed to the central hub by rivets. each segment consists of 4 plates, 2 w

15、orking as facing springs and 2 as carriers.3. measurements measurements were performed at the department of power train development of the institute for product development (ipek) at the karlsruhe university (th) research university, where a category iv component test rig is used for tests of new fr

16、ictional materials and examinations of new materials in real clutch disks. real conditions are applied by the simulation of driving resistance (e.g. starting in the plane, starting at the hill). it is a component test rig leveled on the fourth position of the tribological testing environment.in orde

17、r to give an idea of dimensions: the equipment length is about 4-5m. the two electric motors and the axial force are controlled independently by computer; thereby many operational states can be realized. this enables the equipment to complete a myriad of tribological measurements all while properly

18、modeling the operation of a clutch disk in a passenger car. it is also equipped with an automatic it measurement system. measurable quantities include the following:l two heavy-duty electric motors (150 kw, baumuller ds 160l-305),l device suitable for exerting axial force,l torque meter (manner sens

19、ortelemetrie mf100),l axial force meter,l steel disk in friction,l replaceable head to affix the device to be tested,l temperature along two different radii at 0.4mm below the abrasive surface of the steel disk (omega hjmtss-im100u-150-2000,j-typeiro-constantan thermocouples),l revolutions per minut

20、e for both sides (polytene lsv 065).the greatest challenge out of these is temperature measurement as we would like to know the temperature of the revolving steel disk. the two thermoelements placed in the steel disk forward data to the computer through a wireless blue tooth system and are placed 0.

21、4mm below the abrasive surface of the steel disk on the two opposite arcs of the clutch disk.3.2. measurement processdue to component analyses and cost reduction only one side of the clutch disk is mounted with ceramic facings. thus, the clutch disk and its fitting will be referred to as the ceramic

22、 side, and the abrasive steel disk with its environment revolving together will be referred to as the steel side. in the course of measurements, data were collected at a sampling frequency of 100 and 1000hz. measurements were conducted according to the time curves.the measurement starts by increasin

23、g the revolutions per minute of the steel side (the driving side) to a specific value (1500 rpm here). then the ceramic side (the driven side), held at zero rpm, is pushed towards the steel disk and the axial force is applied until a designated value is reached (nominally 4200n here). upon reaching

24、the designated axial force the ceramic side is released and the two sides start to synchronize. a few seconds after synchronization, the axial load is discontinued and after some time both the steel and the ceramic sidesrevolving at the same speedare slowed down. this is deemed to be one measurement

25、 cycle. ten cycles are completed in the course of a single measurement. during application of the axial force the ceramic side is held at zero rpm until the desired force is reached to ensure synchronization occurs at nearly the same time of each cycle. this is unfavorable from the viewpoint of both

26、 measurements and calculations. measurements are usually conducted by changing only 3 parameters: the speed, the axial load and the inertia. the following figures are applied in various combinations:l speed n: 700, 1100 and 1500 (rpm),l axial force f: 4200, 6400 and 8400 (n) andl inertia i: 1, 1.25

27、and 1.5 (kgm2).experimental measurements are launched with approx.10-15 min intervals, during which the system cools down to about 30-40 1c. this makes calculations difficult, as the exact temperature distribution of the system is not known at the commencement of the measurement. however, it can be

28、assumed that a period of 10-15min is sufficient for a nearly homogeneous temperature distribution to be produced. the parameters for the following simulation have been chosen for an intermediate case with a speed n =1500 rpm, an axial force f = 4200 n and an inertia i = 1 kg m2.4. calculations of he

29、at generation the mechanical energy consumed during the friction of two bodies is transformed into heat. the generated heat can be calculated by the following simple formula: q =f w . where m is the the frictional coefficient; v is the sliding velocity; f is the force perpendicularly compressing the

30、 surfaces. and the heat flux density per surface unit is q=p wm2. where p is the the pressure calculated as a ratio of the force and the contacting surface. as the ceramic tablets are placed at two different radii along the clutch disk, the heat generated must be calculated separately for each radii

31、. sliding can be divided into two sections. in the first section, the ceramic side is kept in a stationary position by braking, meanwhile the axial load is increased; therefore compression changes in the course of time while the speed difference between the two sides is constant. in the second secti

32、on (at synchronization) the speed difference is equalized while the force value is constant, so velocity changes in time. on the basis thereof, the heat generated is .the nominal contact area is the aggregate of the contacting surfaces of the 24 and 18 ceramic tablets on the given ring. the diameter

33、 of ceramic tablets is: .calculations were performed for the load case to be characterized by the following parameters: .based on experimental measurements a constant friction coefficient of 0.4 was established. .the velocity can be calculated with the knowledge of the radius and the speed. .surface

34、 pressure can be calculated as a ratio of the axial force and the contacting surface. this produces the same figure for each ceramic pellet, assuming an even load distribution. . thus, the maximum values of the generated heat are .in the first section of sliding, the generated heat is rising due to

35、the increase of the load force; in the second section, it is decreasing due to the equalization of the speed difference. it is necessary to know the time of each sliding section in order to be able to specify the generated heat time curve. these can be determined from measurement data series. synchr

36、onization time can be easily determined from the speed of the ceramic side. speed increase is linear. force increase is non-linear. for the sake of simplicity, force increase was substituted by a straight line in calculations so that the area below the straight line is nearly identical with the area

37、 measured below the curve. thus, the time difference between the two terminal points of the straight line is the time of the first sliding section. the above-mentioned method was applied for each cycle and their average was specified. based on these results, the following values were determined for

38、sliding times: .now the time curve of heat generation can be produced. the same curve was used in each cycle as there were no significant differences between parameters in each cycle. the generated heat-calculated this way-will appear as thermal load in the thermal model. it must be distributed appr

39、opriately between the contacting surfaces by taking into consideration heat partition. heat partition requires the contact temperatures to be identical at both surfaces. correct adjustment requires repeated iterations.有限元熱分析的陶瓷離合器1 引言 磨料空轉(zhuǎn)車輛離合器是力封閉聯(lián)軸器。扭矩和高速傳輸被壓緊表面之間產(chǎn)生的摩擦力所保證。應(yīng)用陶瓷是因為它作為摩擦介質(zhì)具有好耐熱和耐磨損性

40、能，提供了機(jī)會以驅(qū)動更高的壓力，以及一個低的密度。因此，一個提功率密度啟用了一個平行的最小化建筑空間。 測量使用陶瓷飾面離合器盤的第一個原型在卡爾斯魯厄大學(xué)的一個實驗室專門從事客車驅(qū)動系統(tǒng)進(jìn)行了測試執(zhí)行。在分析過程中的有限元（fe）模型是將與測量數(shù)據(jù)和測量條件的知識所構(gòu)成。計算的目的是要確定在離合器盤上溫度的分布以及環(huán)境中的在每一時刻的及時測量目。至關(guān)重要的是熟悉的溫度范圍，為了檢驗該系統(tǒng)的耐磨特性。因此，重要信息從測量數(shù)據(jù)中得出。在臨界負(fù)載的情況下，預(yù)計最高溫度必須在時間和空間上進(jìn)行預(yù)測，為保護(hù)接近發(fā)熱體的位置測量工具的。本研究的目的是分析和修改該離合器系統(tǒng)通過改進(jìn)，以提供更好的工作條件熱傳

41、導(dǎo)和系統(tǒng)或增加轉(zhuǎn)化成摩擦熱的能量的對流。此外，人們希望找到更有效的更好的離合器系統(tǒng)設(shè)計方案。計算是由宇宙星空的設(shè)計的軟件進(jìn)行的。在模型開發(fā)階段，非常謹(jǐn)慎，必須采取幾何元素，選擇適當(dāng)?shù)暮喕叽?，并且由于正確調(diào)整的時間步長大量的硬件要求瞬態(tài)計算。熱物性參數(shù)的改變，如表面熱對流化系數(shù)和熱負(fù)荷，必須考慮到到在一個持續(xù)的基礎(chǔ)上在時間和地點方面。離合器系統(tǒng)的分析測試這兩方面，只能通過加熱隔板連接的兩個獨立的模型來管理，根據(jù)該假說認(rèn)為，接觸溫度必須是在兩個相同的雙方，同時他們要有適當(dāng)接觸，其價值需通過迭代來進(jìn)行調(diào)整。計算顯示，該熱分區(qū)按周期變化，它沿不同的內(nèi)，外接觸環(huán)。在不同的冷卻特性下，在陶瓷和鋼之間的結(jié)

42、果是不同的 ，熱流從陶瓷側(cè)面向鋼側(cè)流動。此熱流也通過迭代確定;它的價值也改變了周期和不同沿著所述內(nèi)和外接觸環(huán)。2 采用工程陶瓷作為摩擦材料的第一個原型機(jī)這款檢查過的離合器盤是根據(jù)“ 特定的陶瓷”產(chǎn)品而開發(fā)的，此材料的研發(fā)過程在流程在卡爾斯魯厄大學(xué)的institute for product development (ipek)雜志上發(fā)表過。此開發(fā)過程已經(jīng)具有的可能性，用于連接到一個真實的傳動軸；甚至，它為面板有一個好的初始行為起到一個很好的緩沖作用。磨料配件必須符合以下基本要求：1. 根據(jù)高摩擦系數(shù)高扭矩傳遞2. 高舒適度（通過自感應(yīng)抖動無共振）3. 均勻的溫度分布4. 低磨損特性開關(guān)的一個關(guān)

43、鍵因素是摩擦面.在設(shè)計極限方面，必須謹(jǐn)慎采取選擇合適的材料。高而恒定的摩擦系數(shù)，耐磨損和耐熱性是理想的特性。離合器圓盤能代替通常 應(yīng)用環(huán)形磨料入口兩排ssic的（燒結(jié)）陶瓷顆粒。這些小球被放置在6個單獨的段位。該段由鉚釘固定到中心輪轂。每個段由4片組成，2個工作面對著彈簧和2個作為載體。3 測量3.1 測量設(shè)備 測量是在卡爾斯魯厄大學(xué)（th）研究型大學(xué)的動力傳動系完成的，同時也是用于測試新的摩擦材料和新材料在實際離合器片中檢測的地方。真實情況是通過驅(qū)動電阻的仿真應(yīng)用（例如，開始在平面上，開始于山）的試驗裝置。這是一個組件試驗臺夷為平地在摩擦測試環(huán)境的第四位。為了給維度的概念：設(shè)備長度大約4-5

44、m 。兩臺電動機(jī)和軸向力是由計算機(jī)獨立控制;因此許多運營可實現(xiàn)的狀態(tài)。這使得設(shè)備來完成一個摩擦學(xué)測量無數(shù)，而所有正確建模在乘用車上的離合器盤的操作。它還配備用自動的it測量系統(tǒng)?？蓽y量的量包括以下內(nèi)容：1. 2個重型電機(jī)（150千瓦，baume米勒ds160l-305）2. 設(shè)備適用于施加軸向力3. 扭力計（sensortelemetrie mf100）4. 軸力計5. 鋼盤的摩擦6. 可更換的頭部貼上設(shè)備進(jìn)行測試7. 溫度沿兩個不同的半徑處為0.4mm以下的鋼盤（歐米茄hjmtss-im100u-磨料表面 150-2000，j鐵康銅熱電偶）8. 每分鐘轉(zhuǎn)數(shù)為雙方（polytec lsv065）。這里最大的挑戰(zhàn)是這些我們想知道的旋轉(zhuǎn)鋼盤面上溫度的測量。兩個熱元件放置在鋼盤通過無線藍(lán)牙數(shù)據(jù)轉(zhuǎn)發(fā)給計算機(jī)系統(tǒng)和被放置為0.4mm以下的研磨面鋼盤上的兩個相對的圓弧的離合器盤。3.2 測量過程為了測量由組