純電動汽車差速器設(shè)計【含CAD圖紙、說明書】
純電動汽車差速器設(shè)計【含CAD圖紙、說明書】,含CAD圖紙、說明書,電動汽車,差速器,設(shè)計,CAD,圖紙,說明書
畢業(yè)設(shè)計（論文）任務(wù)書
畢業(yè)設(shè)計（論文）題目：純電動汽車差速器
原始資料：
EV汽車
汽車總質(zhì)量：1880 kg
后橋滿載軸荷：1003 kg
發(fā)動機最大功率：33.5 kw/4000 rpm
發(fā)動機最大轉(zhuǎn)矩：72 N·m/3000 rpm
最高車速：120 km/h
輪胎：P195/50R15
畢業(yè)設(shè)計（論文）主要內(nèi)容：
1、 差速器在電動車上的應(yīng)用
2、 差速器的設(shè)計原理
3、 差速器零部件分析
4、 摩擦片機構(gòu)的計算
5、 差速器行星齒輪選取
主要參考文獻：
1. 《機械設(shè)計》 高等教育出版社 邱宣懷
2. 《機械結(jié)構(gòu)設(shè)計》 機械工業(yè)出版 吳宗澤
3. 《機械摩擦無極變速器》機械工業(yè)出版 阮忠唐
4. 《電動汽車原理與應(yīng)用》 機械工業(yè)出版 王震坡
5. 《機電一體化設(shè)計指導(dǎo)書》 機械工業(yè)出版 尹志強
學生須提交的文件：
1、 電動汽車差速器的零件圖
2、 設(shè)計說明說
3、 外文翻譯
4、 開題報告
5、 任務(wù)書
進度安排：
第四周 布置題目 收集資料 熟悉內(nèi)容；
第五周 編制開題報告；
第六周 外文翻譯；
第七周 方案討論；
第八周 確定總體方案；
第九周 計算主要數(shù)據(jù)；
第十周 制作零件圖；
第十一周 制作零件圖；
第十二周 分析繪制裝配圖；
第十三周 整理說明書；
第十四周 整理說明書；
第十五周 編寫設(shè)計計算說明書，形成畢業(yè)設(shè)計全部文件，準備答辯；
第十六周 開始答辯
專業(yè)班級 學生
設(shè)計（論文）工作起止日期 2019.3.26—2019.6.13
指導(dǎo)教師簽字 日期
專業(yè)（系）主任簽字 日期
New Energy Vehicle Innovative Electric Differential and Drive Bridge--A Practical Study of Electric Vehicles
Author: Schaeffler Published: 2012-09-05
Abstract: This article describes an innovative electric active differential for hybrid and electric vehicles that has been bench tested and installed on a pure electric vehicle in a project. Electric differentials based on the principles of FZG not only enable purely electric drives, but also make active lateral torque distribution possible. The purpose of developing an electric drive differential is to optimize the electric drive system, including maximizing efficiency, as well as the industrialization of design and functional verification of electric drive torque distribution.
Key words: lightweight differential, electric active differential, electric car
1 Introduction
Due to global warming and the lack of fossil fuels, the development of electric vehicle drive devices has become a leader in the research of new energy vehicles. The Federal Government of Germany hopes that the country will become the market leader in the field of electric vehicles in the next ten years.
Even without electric vehicles, our car ownership keeps increasing, which also leads to an increase in traffic density. Therefore, in order to reduce the accident rate, the EU launched the eSafety campaign to achieve a bold goal that will reduce road traffic deaths by half in 2010. But it is impossible to achieve this goal simply by improving road conditions. Vehicle transmission systems and control systems must be more intelligent so that they can proactively correct driver mistakes. It is different from some driver assistance systems that are already in development or under development; the device proposed in this paper for a purely electric drive system is a completely new invention.
When Schaeffler first developed the spur gear differential, it inspired the installation of the differential speed control motor coaxially to the differential. The initial design shows that this is a very compact transmission system. If the differential can combine the integrated reducer and the auxiliary motor to realize the distribution of transverse torque between the vehicles, the handling, comfort and safety of the driving will be significantly improved.
Schaeffler's early development team at Herzogenaurach designed the prototype of this system, called the Active Electric Differential, and carried out in-depth testing and research on the bench. The team then installed two active differential systems on an AWD electric vehicle to further verify the advantages and limitations of the electric drive torque-oriented distribution system in the front, rear, and co-acting modes of the car.
2, Schaeffler lightweight differential
Traditional differentials have the ability to balance different speeds between two wheels, such as when a vehicle is turning. In this case, the wheel with a large track radius rotates faster than the wheel with a small track radius. However, the torque distribution ratio is fixed at 50:50%.
Schaeffler applied planetary gear technology to develop a spur gear differential with optimized volume and weight, which we call a light-weight differential (Fig. 1). The differential has two different types of symmetric gear and asymmetric gear. See (a) and (B) in Figure 1.
The (a) type differential has 2 sets of planetary gear sets, and each set of planetary gear sets has 3 planetary gears, so there are 3 pairs of planetary gears. On the left and right sides, the three planetary gears of the same planetary gear pair mesh with their corresponding sun gears; and the three pairs of planetary gears belonging to different planetary pairs on the intermediate region mesh with each other. This design will leave a gap between the two sun gears.
The (B) type differential was originally designed to maximize the use of lateral space between the (a) model differential and the two sun gears, further reducing the differential's size and weight. This design moves the planetary gear engagement plane to the meshing plane between the planet gear and the sun gear. Taking the Schaeffler lightweight differential instead of the traditional tapered gear differential can reduce the weight of the mid-size car's rear axle by more than 30% and almost 70% of the cross-axis space.
Figure 1: Schaeffler light-weight differential (a, symmetrical sun gear and planet gears; B, asymmetrical gears)
3, active differential system
Unlike the aforementioned conventional differential, the so-called active differential not only balances the rotational speed difference of the two wheels but also can independently distribute the driving torque to each wheel. This is the torque-oriented distribution technology. Due to the different circumferential forces on the wheels, a yaw torque is generated on the vertical axis of the vehicle, which directly affects the driving dynamics and stability. Unlike the ESP system, the active torque distribution control system does not slow down the vehicle when it intervenes. An active differential with a torque-oriented distribution function is mounted on the rear axle and can produce the same effect as the current ESP system, that is to prevent understeering of the front wheels of the vehicle; and thus to improve the safety and power performance of the vehicle, see FIG. 2 .
The different wheels of the coaxial shaft are subjected to different driving/braking torques to generate a yaw torque on the vertical axis of the vehicle. Active lateral movement can significantly improve the dynamic performance of turning and reversing the vehicle. Agile driving performance not only improves driving comfort, but also improves driving safety, such as changing lanes in vehicles.
With a reasonable axle movement design, the different driving forces acting on the wheels on both sides of the steering axle will generate a yaw torque in the direction of the steering rod. Thus, steering lock or steering assist can be achieved by setting the lateral torque distribution.
More, for example, due to the negative effects caused by lateral wind and pavement trenches, it can be corrected through dynamic lateral torque distribution control to obtain a more worrying driving feeling. In addition, the yaw torque can achieve consistent driving performance. For example, the turning radius generated for a given steering angle is constant, independent of the vehicle's load and speed; this is at least feasible in principle.
Figure 2: Advantages of active transverse torque distribution
The wheel torque control is achieved by controlling the wheel speed. According to the preset slip curve, a torque difference can be generated between the wheels. Figure 3 shows the relationship between wheel speed and drive torque.
As shown in Fig. 3, in the initial state (a), the vehicle travels in a straight line, both rear wheels run at the same speed and driving torque, and the slip rates produced by the two rear wheels are the same. We assume that the revolver is now braking. It is very difficult to drive the right wheel at this time because the driving torque of the vehicle is constant. State B shows the relationship between the left wheel braking torque and the required braking slip. However, regardless of the braking torque on the left rear wheel, the driving torque on the right wheel must be increased to the level of State C to ensure that the total driving force is not changed. The sliding curve of Figure 3 shows the required working point of the right wheel. .
Figure 3: Relationship between wheel slip ratio and driving torque
By means of the relationship between the slip ratio and the driving force curve, the wheel speed must be changed in order to realize the directional distribution of the driving torque on the drive shaft, and vice versa. Therefore, in order to achieve the differential torque required for the torque directional transfer function, one wheel must be accelerated with respect to the other wheel. The first clutch-based active torque distribution system was applied to Mitsubishi Lancer. Similar mass production was also applied to the BMW X6 and Audi S4 systems. These specially designed drive units have additional drive gear sets and hydraulically controlled disc clutches or electromechanically controlled disc brakes that accelerate one half of the rear axle, producing differential speed and actively distributing torque between the two wheels. (Refer to Figure 3)
Fig. 4: Active differential of the hydraulically-controlled disc clutch (1, tapered gear differential, 2, coupling transmission, 3, disc clutch, 4, drive torque)
4 electric active differential
The electric active differential is the best alternative to a conventional differential based clutch with a coupled transmission that directly controls the differential speed through an electric device connected to a differential gear. At present, the integrated system of the integrated electric actuator device and the mechanical torque distribution mechanism is only in the conceptual design stage, and the actual hardware has not yet been realized; not to mention the system as an active (differential) system in, for example, emergency avoidance, etc. Under the circumstances to apply the example.
Here we use the traditional simple bevel gear differential to describe the function of the active differential, see Figure 5. If the rotary motion of the differential planet gears is coupled to an electromechanical device, this device is driven by the differential. In turn, sending a speed through the electric device can also produce differential motion on the gear between the wheels (the sun gear on the half bridge of the differential). Because the driving torque generated by the external electric device makes the balance bar of the planetary gear unbalanced, the torque distribution of the differential also changes. This means that any theoretically possible wheel-side torque and speed distribution is achieved on the wheels.
The basic advantage of this type of active differential is that it no longer requires any extra components because the torque distribution is done directly inside the differential. When the rotation speeds of both wheels are the same, the electric device is at a standstill and the torque is only provided when the torque is actively distributed. However, the disadvantage of the design shown in Fig. 5 is that the torque transmission ratio between the electric device and the differential is low (beveled), and the electric device must be rotated along with the half shaft. In order to avoid these disadvantages and preserve the advantages of the electric differential, we have made important improvements to the differential according to the FZG principle. The modified differential is shown below.
Fig. 5: Principle of electric differential (1, bevel gear differential, 2, transmission, 3, torque-distributed motor, 4, drive gear)
In Fig. 6, the spur gear differential (1) distributes the torque equally to both drive wheels when the control function is off.As shown in Figure 1b, this differential is a planetary gear device consisting of two asymmetrical sun gears and three pairs of intermeshing planets. The planet gears of the differentials mesh with the sun gears, and each sun gear is connected with one wheel. This form of spur gear differential can be combined with an external planetary gear device, which is very important. The three pairs of planetary gears in a spur gear differential theoretically implement the same function of a bevel gear between shafts in a bevel gear differential.
According to the principle of Fig. 5, the speed difference between the two wheels can be generated by the relative motion of the planetary gear sets of the spur gear differential; it can be achieved by the driving planetary gear device (2) and the coupling gear (3). The composition of the transmission is completed. The active planetary gear device (2) is coaxial with the differential (1) and shares the same planetary gear among them. If the sun gear in the differential (2) rotates on the ring gear, its planetary gear is forced to rotate at a corresponding speed, which is the reason why the speed difference on the wheel can be generated. The relative speed of the inner planet gears in the spur gear differential corresponds to the speed of the planet gears in the bevel gear differential in FIG. 5 .
Fig. 6: The principle of electric differential (1, spur gear differential, 2, active planetary gear, 3, coupled transmission, 4, torque-oriented distribution motor, 5, driving gear)
Coupled transmissions reduce the wheel-side torque required for lateral force distribution, thereby reducing the directional torque of the motor. Different from the concept of the original FZG, the two identical planetary gear units of the coupling gear (3) share the same shaft. Torque is output through two separate but identical planetary systems, one of which is connected to the sun gear of the ring gear and the other of which is connected to the outer ring gear. Simulations in the early stages of development show that this arrangement is less sensitive to the deformation of the planetary gear arrangement than the original design of the FZG through two independent planet carrier outputs. The deformation of the coupling gear causes the torque-directed distribution unit to tend to self-lock.
One of the sun gears in the coupling gear (3) is fixed to the housing and the other sun gear is connected to the control motor. When controlling the output torque of the motor, the coupling actuator rotates the two outer ring gears in the same (3) in the opposite directions, and the opposite torque is generated on the sun gear and the outer gear of the coupling gear (2).
If the control motor is stationary, no differential motion can occur on the differential planet gears. Because the speed of the sun gear and the ring gear of the coupling gear are the same at this time, of course, the rotation speed of the wheel is also the same. If the coupled transmission does not rotate, no differential torque will be generated, the wheel torque is the same (drive loss is not accounted for), and the control motor does not provide any torque. When the vehicle is cornering, the control motor is also passive and does not require differential torque. As shown in Figure 6, if the coupling actuator is closed, the device will operate as a conventional differential, but with a slightly higher self-locking value. For a system where each wheel has a drive motor, the system in this paper requires much less power to implement the torque distribution function. The sum of the wheel drive torques is not determined by the coupled drive system, ie the torque difference between the wheels. Therefore, the control system can be quite simple.
Fig. 7: Schaeffler's schematic diagram of the active differential (1. Spur gear differential (asymmetrical), 2) Active planetary gear, 3, Coupled transmission, 4, Torque oriented motor, 5 , planetary reducer, 6) main drive motor)
Fig. 8: Schaeffler electric active differential design
The Schaeffler senior development team integrated the electric torque distribution system shown in Fig. 6 into an electric drive unit. This electric drive unit was designed for a full-time, four-wheel-drive midsize car (Figure 7). The active electric differential consists of the following two basic units: “electric differential” and “active torque distribution system” [2][3]. Both of these basic units are coaxial with the axles of the car, and the light-weight differential is its connecting device. The final design of the active differential device is shown in Figure 8. The main technical parameters are listed in Table 1.
5 Schaeffler Electric Vehicles
In the early development phase of the active differential, Schaeffler not only tested on the bench but also tested the entire vehicle in order to test its performance under actual conditions as much as possible. We chose the 1.8TSI AWD version of the Skoda Octavia Scout as a platform for testing electric vehicles. The full-time four-wheel drive system provides the greatest degree of freedom in investigating the role of the active torque distribution system in the front and rear axles. This means that the conditions of the front drive, rear drive, and four-wheel drive can be tested separately under the same driving conditions. And it can be compared with the original car without an active torque distribution system.
Figure 9 shows Schaeffler's electric car. The active electric drive differential (1) is simultaneously mounted to the front and rear axles of the vehicle as shown in FIG. The current of the main drive motor and the torque-oriented distribution motor is provided by four identical inverters (2). Two of the inverters are located in the engine compartment, and the other two inverters are located where the spare tire was originally placed. The air-cooled lithium-ion battery (3) with a capacity of 17.8 kWh is partially disposed on the engine shaft passage and is partially disposed at the original tank position. The battery consists of 110 3.6V 45Ah battery cells and provides 400V for the high voltage inverter. An on-board charging system (4) is mounted on the electric vehicle, and its electric plug (5) can use either 220V charging or fast charging. In addition, a DC/DC inverter (6) is provided between the high voltage circuit and the low-voltage circuit and ProTronic, the original vehicle control unit provided by AFT. Technical data on Schaeffler's electric vehicles are summarized in Table 2.
Fig. 9: Schaeffler electric vehicle (1, active differential, 2, DC/AC inverter, 3, battery, 4, battery charger, 5, charging plug, 6, DC/DC transformer, 7, Vehicle Control Unit ProTronic.)
Schaeffler Electric Vehicles officially started testing vehicles in October 2010. The following results have been obtained from the drum test benches and road tests to date:
l Although the electric vehicle weighs 350 kg more than the original car, the electric prototype has the same driving comfort and handling as the original car.
When the torque-oriented distribution motor is not in operation, no negative effect of the rotational quality of the torque-oriented distribution system on the power and noise of the vehicle is found during the cornering process.
The innovative electric drive torque distribution system works equally well in the front and rear axles of the car. With a simple parameter matrix setting, the distribution of torque differences can vary with the steering angle and the vehicle speed. Next we will implement a complete torque-oriented allocation strategy.
The active differential can achieve a maximum of 2000Nm torque difference, and the physically reasonable limit is approximately 1500Nm.
The rear axle torque distribution system of the rear axle can stabilize the vehicle body, so it is very helpful for the driving safety of the vehicle. The torque-oriented distribution system of the front axle significantly improves the controllability of the vehicle, making the control of the vehicle more sensitive, comfortable and full of fun.
Since the extra high-voltage battery is installed to increase the weight of the vehicle and the resulting mass distribution changes, the chassis of the vehicle must be retrofitted; the vehicle chassis is torsionally reversed with the help of active torque distribution for extreme driving.
6 Conclusion
Schaeffler's active electric drive differential system is the optimal platform for future control strategies. With intelligent lateral torque distribution system and spur gear differential combination. When the active electric drive differential is used on both axles, the longitudinal distribution of vehicle torque can also be achieved.
A further purpose of this drive system is to achieve the best integration of Schaeffler Group and Contine
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