4座微型客貨兩用車設(shè)計(jì)(后驅(qū)動(dòng)橋、后懸設(shè)計(jì))
4座微型客貨兩用車設(shè)計(jì)(后驅(qū)動(dòng)橋、后懸設(shè)計(jì)),微型,客貨兩用車,設(shè)計(jì),驅(qū)動(dòng)
Suspension performance testing
The suspension system, while not absolutely essential to the operation of a motor vehicle, makes a big difference in the amount of pleasure experienced while driving. Essentially, it acts as a "bridge" between the occupants of the vehicle and the road they ride on.
The term suspension refers to the ability of this bridge to "suspend" a vehicle's frame, body and powertrain above the wheels. Like the Golden Gate Bridge hovering over San Francisco Bay, it separates the two and keeps them apart. To remove this suspension would be like taking a cool dive from the Golden Gate: you might survive the fall, but the impact would leave you sore for weeks.
Think of a skateboard. It has direct contact with the road. You feel every brick, crack, crevice and bump. It's almost a visceral experience. As the wheels growl across the pavement, picking up a bump here, a crack there, the vibration travels up your legs and settles in your gut. You could almost admit you were having fun, if you didn't feel like you were gonna toss your tacos at any second. This is what your car would feel like without a suspension system.
In the interests of road safety, it is logical to include in periodic roadworthiness tests an inspection of vehicle suspension performance. The results of tests with a prototype machine are presented and a specification proposed for a valid suspension test.
Demonstrations organized by the European Shock Absorbers Manufacturers’ Association ( EuSAMA) in many countries have drawn attention to the importance of correctly functioning shock absorbers. In the United Kingdom it is anticipate that the Department of the Environment will include a specific shock absorber check in the MOT Test with effect from January 1977.
Of the machines currently available for testing shock absorbers without removing them from the vehicle, there is no real consensus of opinion concerning their validity to evaluate suspension safety objectively. But it is felt that possible more stringent legislation on European periodic vehicle tests in the future will demand a form of objective testing on equipment that is incapable of erroneous interpretation.
Since its formation in 1971 EuSAMA has realized the imnportance of the problem, and initially charged its technical sub-committee with the task of examining and analyzing the various test machines then available. Two basic types of machine were offered at that time for diagnosing faulty shock absorbers. These were:
Machines which lift up the wheels on an axle by about 100 mm and then let them drop. The subsequent displacements of the body on each side are recorded and the results compared with preset values for the particular vehicle and the suspension position, front or rear. Such a machine simulates a step input and records the subsequent body movements (see Fig 1).
Machines which measure wheel movements induced by the exitation of the suspension through a frequency scan from above resonance frequency to zero, applied by means of a spring-supported platform under the tyre. Results are recorded in the form of wheel displacement against time. While passing through the wheel bounce resonant frequency the maximum amplitude is obtained and this is compared with preset values for the particular vehicle and the suspension position front or rear (see Fig 2).
A third machine, introduced later, measures phase shift induced by the excitation of the suspension at a constant frequency and stroke, applied by means of a vibrating platform under the tyre. The phase shift between the moment of excitation and the force-reaction is recorded and the result is compared with preset values for the particular vehicle and suspension position (see Fig 3).
These systems have three fundamental drawbacks:
A: The actual damping is compared with the original damping the limit being a certain degradation in comparison with the original performance. The original performance, however, can already be marginal.
B: The problems of limit setting, namely by whom should the limits be set and what are the criteria they should about? At present there is hardly any relation between set limits and acceptable performance in practice.
C: The practical problem of various limits for different vehicle types and their suspensions. This requires comprehensive reference manuals that need continuously updating.
Despite these fundamental drawbacks, examples of the ? widely used test machines were put through their paces by the Automotive Engineers Laboratory of the University of Ghent, as well as by several EuSAMA members. As expected, the first conclusion is that no test method which does not include dismantling the shock absorbers from the vehicle is able to furnish information concerning the shock absorber alone, and it is in fact the whole of the vehicle suspension system that is tested. This can be considered as a positive aspect of testing, since the whole of the suspension should be in good condition for safety; although the shock absorber is the component most likely to deteriorate with use, other defects such as incorrectly inflated tyres, broken springs or seized ball-joins should if possible be diagnosed.
Of the other factors which influenced test results it was found that all machines gave results that were much affected by shock absorber temperature. In the case of the drop type testing machines, defects in shock absorbers caused by high frequency excitation could not be detected. With the frequency scan type of machine, approximately constant force input implies a big difference in results between vehicles with soft or hard suspension, so that changes in springs from normal to heavy duty (which the operator may be incapable of identifying ) can considerable affect the result.
Each make of machine had its own characteristics, but as the basic test principles were considered to be unacceptable these details will not be presented here.
After due consideration the technical sub-committee advised the General Assembly of EuSAMA that although the existing machines, when correctly operated, could help to diagnose many faulty shock absorbers, a responsible association could not authorize such equipment as the parameters measured were not considered technically representative of any particular aspect of roadworthiness.
Taking brake testing as an example, it was noted that test machines give a direct reading of braking efficiency as a percentage of g without the need to identify vehicle type or to use reference manuals. Similarly, minimum braking performance levels can be set for all automobiles irrespective of model, so that a customer knows immediately if his brakes need attention, Some machines show brake imbalance, but do not indicate which component is faulty.
Applying the same principles to vehicle suspension, it should be possible to propose a test which furnishes a direct reading as a value or preferably as a percentage, to indicate whether a suspension is considered satisfactory from the viewpoint of safety. Moreover, this must be achieved objectively, that is to say without need of any identification, interpretation or reference to manuals by the test operator.
The technical sub-committee therefore looked for a parameter which could be considered a suitable criterion of safety in relation to vehicle suspension. As stated earlier, there is only one component normally subject to deterioration with use—the shock absorber. So the role of the shock absorbers must first be defined. These have two functions to perform: to damp the movement of the vehicle body on its springs and to control wheel bounce.
The permitted movement of a vehicle body on its springs is very much a matter of taste, and it is largely in the control of such movement that a sports shock absorber differs in damping characteristics from a shock absorber aimed at optimum comfort. The movement of a body on its springs does, of course, materially influence roadholding but in reality few ordinary drivers are capable of reaching the limits of the modern car in this respect, so the value of body damping is relatively unimportant for safety measurements. In any case, most drivers of a vehicle with poor body damping will quickly limit their speed and manoeuvres to the vehicle’s handling capacity.
Wheel bounce, on the other hand, is a measurable phenomenon and the dangers of vehicles with uncertain wheel contact are well known. Both cornering and braking performance are well known. Both cornering and braking performance are limited by tyre anherence to the road; this is dependent on the vertical wheel contact as well as the tyre’s own properties.
A parameter which permits the objective measurement of one aspect of roadholding, and therefore of vehicle suspension safety, was thus isolated but it was still necessary to be able to express it in terms that could be readily interpreted.It was proposed, therefore, to measure the minimum remaining vertical contact force between tyre and road under a given excitation at wheel-bounce frequency and to express it as a percentage of the static wheel load. Such a possibility was discussed at a meeting between the technical sub-committee and Dr Verschoore of the University of Ghent. A general concensus of opinion in favour of such a test was reached, though some members expressed doubts concerning the possibility of measuring this parameter in practice, as well as doubts concerning the results Aparamet。.
At a later date the sub-committee was informed that a prototype machine of German origin, using approximately the principle outlined above, had been submitted for evaluation to the University of Ghent. After certain recommended modifications had been performed, tests by both the University of Ghent and a member company of EuSAMA demonstrated the possibilities of such a test, and amply justified the technical sub-committee’s decision concerning the parameter to be measured.
Details are given below of the tests performed and the results obtained on a prototype machine, developed by Maschingfabrik Koppern & Co, Hattingen, West Germany, and presented by courtesy of S A Monroe International, Brussels, Belgium.
The machine (see Fig 4)
Wheel movement is induced by excitation of the suspension through a frequency scan from about 25 Hz to 0, applied by a platform under the tyre, moving with a fixed stroke of 6 mm. One wheel is tested at a time. Results are recorded in the form of
Minimum dynamic wheel load *100% Static wheel load
The tester’s analogue read-out showed deviations from the maximum dynamic force indicated on the oscilloscope.
Test readings are compared with the impressions of an experienced test driver because no scientific test method for roadworthiness has yet been approved. The final determination of roadworthiness and vehicle comfort is still done by vehicle manufactures by the subjective assessment of one or more experienced test drivers.
The test method outlined below will indicate in nearly all cases whether a vehicle suspension is roadworthy or not. Nevertheless, a visuall inspection of the suspension elements is recommended in addition to the performance test, as incipient failures can sometimes be detected visually before performance deteriorates. Secondly, the test is of the vehicle suspension, wheel by wheel, and will indicate only whether there is a fault; it will not locate the fault, though a skilled operator may be able to diagnose certain defects from the test read-out.
Obviously there is a requirement to design a machine able to detect when a certain percentage of static friction is exceeded. Development work in this area is still required.
While there have been enhancements and improvements to both springs and shock absorbers, the basic design of car suspensions has not undergone a significant evolution over the years. But all of that's about to change with the introduction of a brand-new suspension design conceived by Bose -- the same Bose known for its innovations in acoustic technologies. Some experts are going so far as to say that the Bose suspension is the biggest advance in automobile suspensions since the introduction of an all-independent design.
How does it work? The Bose system uses a linear electromagnetic motor (LEM) at each wheel in lieu of a conventional shock-and-spring setup. Amplifiers provide electricity to the motors in such a way that their power is regenerated with each compression of the system. The main benefit of the motors is that they are not limited by the inertia inherent in conventional fluid-based dampers. As a result, an LEM can extend and compress at a much greater speed, virtually eliminating all vibrations in the passenger cabin. The wheel's motion can be so finely controlled that the body of the car remains level regardless of what's happening at the wheel. The LEM can also counteract the body motion of the car while accelerating, braking and cornering, giving the driver a greater sense of control.
Unfortunately, this paradigm-shifting suspension won't be available until 2009, when it will be offered on one or more high-end luxury cars. Until then, drivers will have to rely on the tried-and-true suspension methods that have smoothed out bumpy rides for centuries.
車輛與動(dòng)力工程學(xué)院畢業(yè)設(shè)計(jì)說明書
4座微型客貨兩用車設(shè)計(jì)
(后驅(qū)動(dòng)橋、后懸設(shè)計(jì))
摘 要
本設(shè)計(jì)為4座微型客貨兩用車的后驅(qū)動(dòng)橋、后懸架設(shè)計(jì)。參照現(xiàn)有的生產(chǎn)技術(shù)水平,綜合考慮生產(chǎn)成本,以及使用條件等多種因素, 經(jīng)過收集各類型的后驅(qū)動(dòng)橋、懸架的資料、實(shí)車觀測(cè)和老師的指導(dǎo),完成了本次設(shè)計(jì)。
本次設(shè)計(jì)確定采用整體式驅(qū)動(dòng)橋。其主減速器為單級(jí),采用準(zhǔn)雙曲面齒輪傳動(dòng),差速器采用普通對(duì)稱式圓錐齒輪對(duì)稱式圓差速器,全浮式半軸,整體鑄造式驅(qū)動(dòng)橋殼。主減速器齒輪主要設(shè)計(jì)的是雙曲面齒輪的尺寸、校核及材料選擇;差速器主要計(jì)算的是對(duì)稱式圓錐齒輪的主要參數(shù)計(jì)算及校核;半軸設(shè)計(jì)主要是根據(jù)強(qiáng)度來確定半軸的半徑和半軸的結(jié)構(gòu)設(shè)計(jì)及材料與熱處理;驅(qū)動(dòng)橋橋殼既是承載件又是傳動(dòng)件,因此橋殼需要有足夠的強(qiáng)度和剛度。
后懸架采用鋼板彈簧式非獨(dú)立懸架,其需要計(jì)算的內(nèi)容比較廣泛,但也主要是集中在對(duì)彈性元件的計(jì)算上。計(jì)算包含了從滿載弧高,各鋼板彈簧片長(zhǎng)度、厚度、寬度,到整個(gè)懸架系統(tǒng)的動(dòng)、靜撓度值的確定。這是因?yàn)樵趹壹芟到y(tǒng)中,鋼板彈簧既是它的彈性元件又是它的導(dǎo)向機(jī)構(gòu),是其最為重要的部件。
綜合各部分的設(shè)計(jì)與校核的結(jié)果,本次設(shè)計(jì)基本能滿足其設(shè)計(jì)要求。
關(guān)鍵詞:后驅(qū)動(dòng)橋, 整體式,非獨(dú)立懸架,鋼板彈簧
THE DESIGNING FOR THE MINIATURE MOTORCAR TO CARRY PERSONS AND GOODS WITH 4 SEATS
(THE DESIGN OF BACK DRIVING AXLE AND REAR SUSPENSION)
ABSTRACT
This design is for the back driving axle and back suspension of the miniature motorcar to carry persons and goods with 4 seats. According to the existing production technique level, synthesize the consideration production cost, and use the condition etc. various factor. In weeks , there was much useful information about the back driving axle and the rear suspension collected. With the helping of my teacher ,and observation on vehicle in laboratory , this designing is completed.
This design assurance adopts the whole type to drive the bridge. Its lord decelerates the machine as single class, the adoption allows a curved face wheel gear to spread to move, differ soon the machine adopt the common and symmetry type cone wheel gear symmetry type circle differ soon machine, the whole float type half stalk, hurtle to cast the whole type to drive the bridge hull. The lord mainly decelerate the machine wheel gear what to design is a pair of pit and the material choice of size, school of curved faces wheel gear. Bad soon machine mainly what to compute is the main parameter calculation and school pits of the symmetry type cone wheel gear.The half stalk design is mainly the basis strength to certain structure design and material and hot processingses of the radius and half stalk of the half stalks. Drive the bridge bridge hull since is to load the piece and is to spread to move the piece, so the bridge hull needs to have the enough strength and just degree.
The design of the rear suspension adopts unindependent suspension with steeel spring. It has more data computation.There are entire rate of rear suspension, heavy load arch high ,dynamic distortion quantity,the different length of different leaf brade, thickness and width of them.Those are indispensable data in suspension of a vehicle.
The result of design and school pit of comprehensive each part, this time design basic can satisfy it designs the request.
KEY WORDS:back driving axle, the whole type, unindependent suspension,steeel spring
目 錄
第一章 前言............. ...................... ........1
第二章 驅(qū)動(dòng)橋結(jié)構(gòu)設(shè)計(jì).................................2
§2.1驅(qū)動(dòng)橋的組成與結(jié)構(gòu)方案分析......................2
§2.2 主減速器的結(jié)構(gòu)形式的分析和確定..................2
§2.2.1 主減速器傳動(dòng)齒輪的類型......................2
§2.2.2 主減速器的減速形式..........................3
§2.3差速器的方案分析及確定......................... .3
§2.4半軸............................................3
§2. 5驅(qū)動(dòng)橋殼結(jié)構(gòu)方案分析............................4
第三章 驅(qū)動(dòng)橋尺寸計(jì)算 .................................5
§3.1主減速器的基本參數(shù)選擇與設(shè)計(jì)計(jì)算................5
§3.1.1主減速比的確定.............................5
§3.1.2主減速器齒輪計(jì)算載荷的確定.................. 5
§3.1.3主減速器齒輪基本參數(shù)的選擇.................. 6
§3.2差速器的基本參數(shù)選擇與設(shè)計(jì)計(jì)算.................17
§3.2.1差速器齒輪的基本參數(shù)的選擇................. 17
§3.2.2差速器齒輪的幾何尺寸設(shè)計(jì)計(jì)算............... 18
§3.3全浮式半軸的設(shè)計(jì)計(jì)算...........................20
§3.4驅(qū)動(dòng)橋橋殼的設(shè)計(jì)計(jì)算...........................21
§3.4.1驅(qū)動(dòng)橋殼結(jié)構(gòu)方案分析....................... 21
§3.4.2驅(qū)動(dòng)橋殼強(qiáng)度計(jì)算........................... 22
第四章 驅(qū)動(dòng)橋強(qiáng)度計(jì)算.................................28
§4.1主減速器準(zhǔn)雙曲面齒輪的強(qiáng)度校核.................28
§4.1.1單位齒長(zhǎng)圓周力............................. 28
§4.1.2輪齒的彎曲強(qiáng)度計(jì)算 ........................29
§4.1.3輪齒的彎曲強(qiáng)度計(jì)算......................... 30
§4.2差速器齒輪的強(qiáng)度計(jì)算...........................30
§4.3半軸強(qiáng)度計(jì)算...................................31
§4.3.1半軸扭轉(zhuǎn)應(yīng)力............................... 31
§4.3.2半軸的最大扭轉(zhuǎn)角........................... 31
第五章 軸承的壽命計(jì)算.................................33
§5.1主減速器主動(dòng)錐齒輪支承軸承的計(jì)算...............33
§5.1.1主減速器主動(dòng)齒輪上的當(dāng)量轉(zhuǎn)矩的計(jì)算....... 33
§5.1.2主從動(dòng)錐齒輪齒面寬中點(diǎn)處的圓周力p的計(jì)算....33
§5.1.3雙曲面齒輪的軸向力與徑向力的計(jì)算........... 33
§5.1.4懸臂式支承主動(dòng)錐齒輪的軸承徑向載荷的確定... 34
§5.1.5軸承壽命的計(jì)算............................. 35
§5.2從動(dòng)齒輪支承軸承校核...........................36
§5.2.1單級(jí)主減速器從動(dòng)齒輪支承軸承徑向載荷的確定. 36
§5.2.2軸承壽命計(jì)算............................... 36
第六章 后懸架結(jié)構(gòu)分析.................................38
§6.1懸架概述.......................................38
§6.2懸架結(jié)構(gòu)形式和布置的分析.......................38
第七章 后懸架參數(shù)確定和尺寸計(jì)算.......................40
§7.1總體布置及其基本參數(shù)...........................40
§7.2彈性元件的設(shè)計(jì)計(jì)算.............................40
§7.2.1鋼板彈簧的布置方案......................... 40
§7.2.2鋼板彈簧結(jié)構(gòu)尺寸參數(shù)計(jì)算................... 40
§7.3后懸架減振器的設(shè)計(jì)與計(jì)算....................... 47
§7.3.1選取相對(duì)阻尼系數(shù)..........................47
§7.3.2最大卸荷力的確定..........................47
§7.3.3減振器工作缸直徑D的確定....................47
第八章 結(jié) 論..........................................48
參考文獻(xiàn)...............................................49
致謝...................................................50
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