外文翻译--汽车变速器控制面临的机遇和挑战

Appendix Challenges and Opportunities in Automotive Transmission Control Zongxuan Sun and Kumar Hebbale Research and Development Center General Motors Corporation Warren, MI 48090 Abstract: Automotive transmission is a key element in the powertrain that connects the power source to the wheels of a vehicle. To improve fuel economy, reduce emission and enhance driving performance, many new technologies have been introduced in the transmission area in recent years. This paper first reviews different types of automotive transmissions and explains their unique control characteristics. We then address the challenges facing automotive transmission control from three aspects: calibration, shift scheduling, and sensing, actuation and electronics. Along the way, research opportunists to further improve system performance are discussed. 1. Introduction to the Latest Automotive Transmission Technologies To improve fuel economy, reduce emission and enhance performance, automotive manufacturers have been developing new technologies for powertrain systems. In the transmission area, emerging technologies 1 such as continuously variable transmission (CVT), dual clutch transmission (DCT), automated manual transmission (AMT) and electrically variable transmission (EVT) have appeared in the market, which is traditionally dominated by step gear automatic transmission (AT) and manual transmission (MT). Among many different technical challenges for developing these new transmissions, system dynamics and control are crucial to realizing the fuel economy and emission benefits while providing superior performance. The basic function of any type of automotive transmission is to transfer the engine torque to the vehicle with the desired ratio smoothly and efficiently. The most common control devices inside the transmission are clutches and hydraulic pistons. Such clutches could be hydraulic actuated, motor driven or actuated using other means (see Figure 1). Therefore clutch/piston control is essential for transmission operation. In both DCT and AMT, clutch control is the key to ensure smooth torque transfer. In CVT, hydraulic piston control is crucial for not only system performance but also device durability. In many of the new automatic transmissions (AT), clutch-to-clutch shift is adopted to reduce the cost and improve packaging. This involves electronic control of both the oncoming and off going clutches and the timing and coordination between them. In addition to eliminating the shift valves, accumulators, etc., clutch-to-clutch control eliminates the coasting clutches and freewheelers, greatly simplifying the transmission mechanical content. The absence of these devices makes the robust control of clutch-to-clutch shifts a challenge. Figure 1. Schematic Diagram of a Clutch With the traditional control system in an automatic transmission with clutch-to-clutch shifts, the oncoming clutch fill process is a major source of uncertainty and it makes the clutch coordination during the shift a difficult task. The fill time of the oncoming clutch varies due to many factors, such as, fluid temperature, solenoid valve characteristics, line pressure variations, and time elapsed between shifts. The commanded fill pressure and the commanded fill time are critical to achieving a good fill and a smooth start to the shift process. Even small errors in calculating these two parameters could lead to an overfill or an under fill, as shown schematically in Figure 2. Some algorithms have been developed to detect the end of fill using speed signals, but none of them has proven reliable and fast enough to prevent overfill spikes. An example of an oncoming clutch overfill during an upshift is shown in Figure 3. The oncoming clutch pressure shows a slight overfill, which results in shift tie-up, causing engine pull down and a big drop in the output torque. A more robust off going clutch control was necessary in this example to avoid a tie-up. While the overfill can be corrected using adaptive schemes for future shifts, the real challenge is in preventing it from happening in the first place. Figure 2. Variations in Clutch Fill Process Figure 3. Effect of Clutch Overfill on an Upshift Currently in most clutch-to-clutch shift production transmissions, the clutch coordination is accomplished by a combination of open-loop, event-driven, and feedback control schemes. Transmission input and output speeds are the primary measured variables used in this control. An adaptive system is used to compensate for shift-to-shift variations and build-to-build variations 2. Recently, an integrated torque based approach using both engine and transmission handles has been proposed. The main difficulty with the torque approach has been in the area of clutch coordination and consequently, consistent shift quality. The automated manual transmissions (AMT) have become popular in Europe. In North America, their potential use is limited because of the torque interruption during shifts that is inherent to their designs. An offshoot of the AMT is the dual input clutch transmissions (DCT), which use two input clutches one for odd gears and one for even gears. DCTs can transmit torque continuously through the shift. All the control issues and challenges during launch and shifts confronting the friction launch transmissions (FL) are also inherent to DCTs. A DCT requires much more calibration work than conventional torque-converter automatics and would be expected to be less refined in drive ability, even in production. On the other hand, because DCTs have more calibration handles, they can be varied to fit different vehicle specifications and different driving conditions. One of the control challenges with torque-converter-less transmissions such as DCT and FL is highlighted in Figure 4. With an undamped driveline, a transient such as a shift event could trigger undesirable oscillations in the driveline, as indicated by the output torque trace. In a friction launch (starting clutch) transmission, the absence of the torque converter leaves the driveline with no hydraulic damping, and consequently, poses many control challenges including vehicle launch feel, undamped behavior during shifts and tip-in / tip-out maneuvers. Without using expensive torque or pressure sensors, the control of a clutch emulating a torque converter is a major challenge. Both hydraulic clutch 3 and magneto rheological fluid clutch implementations have been investigated by researchers. Continuously variable transmissions (CVT) enable the engine to operate in a wide range of speed and load conditions independently from the speed and load requests of the vehicle 4. This feature allows the engine to operate in the optimal region virtually independent of the vehicle speed to maximize the fuel efficiency. Different types of CVT have appeared in the market. The belt and chain drive CVTs use the hydraulic piston to control the sheave position and thus the input-output ratio. The major control challenge is to maintain optimal clamping force to prevent slipping while providing fast ratio control to maximize the fuel economy benefit. Toroidal traction drive transmissions (TCVT) have been examined by many manufacturers as promising alternatives to chain or belt CVTs. TCVTs offer a larger torque capacity and a quicker ratio change capability. A half-toroidal CVT system is unstable under open-loop operation and hence a speed ratio control system is necessary 5. In addition, when a CVT incorporates the geared neutral concept, it eliminates the need for launching devices, such as torque converters and slipping clutches. At the geared neutral point, speed ratio control becomes inadequate and output torque control is required. The control challenges in a TCVT are highlighted in 6-7. Figure 4. Effect of Controlled Damping after an Upshift Electrically variable transmissions (EVT) have appeared in the market recently. The advantages of using electric machines, namely motors/generators, with planetary gear sets include flexibility, controllability, and better performance. Great efforts have been made to extend speed ratio coverage by exploring various planetary gear train arrangements and by exploring regime shift similar to that used in step transmissions. These designs, in general, are quite complex in construction as they involve a number of planetary gear sets and clutches. Elaborate control schemes are required to ensure synchronized regime shift and avoid abrupt torque changes at the output during shifting 8-9. The control algorithms will ultimately determine how drivers perceive hybrid vehicle performance, particularly whether they notice when the vehicle switches back and forth between the electric motor and the engine. Hybrid vehicles may just be a stop-gap technology before conventional internal combustion engines are replaced by fuel-cell propulsion systems. In fuel-cell vehicles, electric motors inside the wheels may completely eliminate the need for transmissions and change the dominant technology in the future 10. 2. Transmission Control Algorithms and Hardware Development Look-up tables with calibrated variables are widely used in automotive transmission control. With the increased functionalities and electronic components, system calibration complexity goes up quickly. This is caused not only by the electronic control of the transmission, but also the coordination with engine and other components in the driveline. For example, with the increasing number of gear ratios in automatic transmissions, the number of variables to be calibrated to realize smooth shifts under all driving conditions goes up quickly. To greatly reduce the development time and improve performance, an automated and systematic approach is required for the calibration process. First, automated tuning process was investigated to calibrate the transmission automatically with little or no human interference. An automated tool set was developed to calibrate automotive powertrain without human-in-the-loop 11. An adaptive online design of experiments (DOE) approach was developed for GDI engine calibration 12. This approach enables the efficient experimental design for nonlinear systems with irregularly shaped operating regions. The same principle can be applied to the automotive transmission calibration. Second, model based control was proposed as an enabler to reduce the number of calibration variables and consequently, the calibration effort and time. However, the uncertain environment and wide operation range present a major challenge to system robustness. The transmission temperature can vary from 40 degree C to 150 degree C, which in turn affects the automatic transmission fluid (ATF) properties. The wide range of operation from completely stopped to rotating at high speed with high load demands precise models and high bandwidth controls. Reference 13 described procedures for determining a set of linearized models and the associated unmolded dynamics for the torque converter clutch in the automatic transmission and applied robust control design to achieve desired performance. Detailed procedures for the development of transmission models for controlling the inertia phase during a shift were presented in 14. Based on these models, robust control can be designed to achieve desirable shift performance regardless of the engine load, ATF viscosity, etc. Variable structure control (VSC) was also investigated for clutch control in an automated manual transmission 15. Results show that VSC control is able to maintain system robustness within the uncertain environment. Third, adaptive learning control was developed to accommodate the uncertain environment and different driving patterns. Artificial neural network (ANN) was employed to model the automotive powertrain using the black-box approach 16. Input and output data are used to train the ANN to emulate the functions of the transmission and its subsystems. A distinctive feature of this approach is that it can emulate not only the steady state operation but also the dynamic/transient operation of the system. The key advantages of this approach include online training using real-time vehicle data and adaptive calibration or control capability. As more number of speeds is added to the transmissions, shift schedule gets more complicated. Since traditional shift schedule only considers vehicle speed and throttle angle to determine shift points, shift busyness has become a concern under certain road conditions, such as hilly terrains. For example, during a winding uphill driving, the driver releases the gas pedal before entering the curve to reduce vehicle speed, and traditional shift schedule may perform an upshift in response to the throttle change. But right after the curve, the driver needs to step into the gas pedal to increase vehicle speed and a down shift may then be executed. Similarly during a downhill driving, an upshift is performed by the traditional shift schedule when throttle angle is decreased, thus unpleasantly reducing the engine brake. By including factors such as road grade, steering angle, vehicle acceleration, etc., flexible shift schedule that is pleasing to the customers and favorable for fuel economy must be developed. Shift busyness avoidance control using fuzzy sets and neural networks have been investigated in the past 17-18. Most of the adaptive shift point algorithms presented in the literature require some knowledge of the mass of the vehicle and the gradient of the road on which the vehicle is travelling. A reliable mass estimation algorithm is lacking in the literature. With good mass information, the estimation of the road grade is straight forward. Recently vehicle navigation system was used to provide some preview information on the road shape and conditions during the shift scheduling process 19. Recent work 20 on shift scheduling also added feedback learning to the fuzzy logic system to update the membership function in real-time to better accommodate different driving patterns. They also extended the work to include not only the AT, but also the AMT, DCT and CVT. A block diagram summarizing the general structure used in gear shift scheduling is shown in Figure 5. Figure 5. Block Diagram of the Gear Shift Scheduling Algorithm To accommodate the ever-increasing demand for computational power, sensing and actuation capabilities, transmission control hardware has been undergoing many changes. Those changes involve all three levels of complexities: the sensing level, the actuation level, and the system level. At the sensing level, new sensing technologies have been pursued to either improve the performance and efficiency of current hardware or enable new actuation technologies. Pressure switches and temperature sensors are used in current production transmissions. To optimize transmission operation, pressure sensor and torque sensor are desirable. The main challenges for introducing these sensors into production units are cost and durability. A piezoresistive semiconductor pressure sensor was evaluated for automotive applications 21. It claims to measure pressures up to 3.5Mpa within +/- 1% of the full scale. Early work on torque sensors can be traced back to early 80s when researchers 22 investigated a non-contact miniature torque sensor for automotive transmissions. Recently magneto elastic torque sensors have been investigated by a number of researchers 23-24. The phenomenon of inverse-magnetostriction that converts material strain into magnetic property changes was exploited to measure transmitted torque. To overcome the harsh environment inside the transmission, special coating technologies were developed to protect the sensing element. A clutch disk integrated torque sensor was also proposed for automotive applications 25. The sensing elements are integrated in the clutch plate to achieve precise and robust measurement. At the actuation level, solenoid valve control technologies were investigated to improve controllability and flexibility of the hydraulic system. For clutch actuation, variable bleed solenoid (VBS) valves are widely used now in place of the pulse width modulation (PWM) valves for better controllability. However, VBS valves suffer from hysteresis and variations due to temperature. Analytical modeling of proportional control solenoid valves was conducted using system identification theory 26. It concludes that the valve bandwidth was limited by the bandwidth of the electromagnetic portion the solenoid. To further enhance system performance, fast and precise valve actuation devices are needed. A new concept 27 for an on/off valve with rotary actuator was proposed to handle flow rate greater than 10lpm with less than 5ms response time. A key feature of this concept is that the valve has a single stage construction, but performs as a two-stage valve. Alternative clutch actuation technologies were also pursued to replace the electro-hydraulic actuators in automatic transmissions to improve fuel economy and performance. Motor driven clutch actuation has been investigated by a number of researchers 28. The major challenges for the electromechanical actuators are the low power density and available electrical power inside the vehicle. Usually some kind of gearing is required to amplify the torque capacity of the motor. Smart material based clutch actuation devices were also developed by a number of researchers. Feasibility of using electro rheological (ER) fluid clutch inside automotive transmission was investigated and desirable properties of ER fluid were proposed for future research 29. Magnetic powder clutch was used as a starting clutch for a CVT equipped vehicle 30. Potential applications of magneto rheological (MR) fluid clutch were discussed in 31. At the system level, there is a new trend of migrating the control electronics from passenger compartment to the transmission case or even integrate the electronics inside the gear box to reduce cost and improve performance and quality 32-33. A new terminology called mechatronic transmission 34 was coined recently to illustrate the integration of control electronics with the transmission device itself. Besides cost and quality benefits, this approach will enable the testing and calibration of the transmission devices right on the assembly line. To enable the gearbox-integrated electronics, new electronic integration and packaging technologies were also investigated to overcome the harsh environment inside the gearbox 35. 3. Conclusions In order to realize maximum fuel economy benefit and provide superior performance, research and development in both control software/algorithm and hardware are required for the automotive transmissions. 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Nagur, N. and Takemura, S., “Development of Small, High Performance Electronics Control Units with Metal Based Printed Circuit Board”, SAE Technical Paper 961023. 附录 1 汽车变速器控制面临的机遇和挑战 Zongxuan Sun and Kumar Hebbale Research and Development Center General Motors Corporation Warren, MI 48090 摘要：在动力系统中，汽车变速器是连接动力源和车轮的关键部位。为了提高燃油经济性、降低排放及增强驱动性能，近几年来，许多新的技术已经在变速器领域出现了。本文首先介绍了不同类型的汽车变速器，并阐述了它们各自独特的控制特点。接着，我们又讨论了在汽车变速器控制上来自三个方面的挑战：校准、转换调度，传感、驱动和电子技术。同时，我们研究了如何进一步改善传动系统性能。 1.介绍先进的汽车变速器技术 为了提高燃油经济性，减少废气排放及提高性能，汽车制造商一直都在开发新的动力传动技术。在变速器领域，新兴的技术，如传动比连续变化的无级变速器（ CVT），双离合器变速箱（ DCT），自动手动的综合变速器（ AMT）和电动无级变速器（ EVT）已经在由齿轮自动变速器（ AT）和手动变速器（ MT） 居于主导地位的市场上出现了。在众多不同的开发这些新型变速器的技术挑战中，系统动力和控制在提供优越的性能的同时，对实现燃油经济性及排放优势也起到了关键的作用。 任何形式的自动变速器的基本功能就是将发动机的转矩平稳有效地传递到具有要求的传动比的汽车上。最常见的变速器控制装置是离合器和液压活塞。这些离合器由液力驱动，马达驱动或由其他方式驱动（见图 1）。因此，离合器 /活塞控制对传动操作是必不可少的。在 DCT 和 AMT 中，离合器是确保转矩平稳传递的关键。在 CVT 中，液压活塞控制对系统性能和设备的耐用性都很重要。在许多新 型自动变速器（ AT）中，采用离合器对离合器转换降低了成本、改进了包装。这不仅涉及到即将到来的和就要过时的离合器，而且涉及到它们之间正时和协调的电子控制。除了淘汰这种转变阀门和蓄电池等，离合器对离合器控制也减少了滑行离合器和自由轮，大大简化了机械传动的内容。取消这些装置使对离合器到离合器转换的控制成为一种挑战。 伴随着具有离合器对离合器转换的自动变速器的传统控制系统，这种即将到来的离合器填充过程是一个不确定性的主要来源，它使在转变过程中协调离合器成为一项艰巨 的任务。即将到来的离合器填充时间会受许多因素的影响 而发生变化，如液体的温度， Return Spring 回位弹簧 Piston 活塞 Hydraulic Fluid Inlet 液压流体入口 Clutch Pack 离合器踏板 图 1 离合器示意图 电磁阀的特点，线压力变化和转变过程中流逝的时间。要求的填充压力和填充时间对于在转变过程中实现良好的填充和平稳的开始过程是至关重要的。即使在计算这两个参数的过程中发生的微小错误也可能导致过满或底部填充，就像图 2示意的那样。有些算法已发展到能够探测出使用高速信号填冲的终端，但是它们中没有一个被证明是可靠的及足够快 去防止尖峰过满。图 3 显示了在挂高速挡的过程中即将发生的离合器过满的例子。那个即将来临的离合器压有轻微的溢流现象，这会产生转换过程中的连锁反应，导致引擎下拉和输出转矩的大幅度下降。在这个例子中为了避免这些连锁反应需要更强大的离合器控制。尽管在未来的调整中可以使用适应性计划去更正过满现象，但是真正的挑战是如何在第一地点阻止它发生。 图 2 离合器 充满 过程中的变化 在目前大多数离合器对离合器转变的变速器中，由于开环控制、驱动控制和反馈控制方法的结合，离合器的协调配合得以实现。在这种控制中，变速 器的输入输出转速是主要的测量对象。一个自适应系统主要用于补偿转换和开发过程中的变化 2。近来，已经有人提出同时使用发动机和变速器产生混合扭矩的想法。这种产生扭矩的方法所面临的主要难题在于如何保证离合器协调和持续的转换质量。 自动手动变速器（ AMT）在欧洲已经开始受到欢迎。由于自身的设计使得在转换过程中扭矩中断，造成这种变速器在北美潜在的发展空间变得有限。 AMT 的一个分支是双输入离合器变速箱（ DCT），它使用两个输入离合器 一个适用于具有单数齿轮的变速箱，一个适用于具有双数齿轮的变速箱。 DCT 可以在转换过 程中持续传输扭矩。在面临摩擦启动 (FL)的启动和转换过程中， DCT 遇到的所有控制方面的问题和挑战也在于它自身的设计。一台 DCT 比传统的液力变矩器自动变速器需要更多的校核工作，同时人们也希望 DCT 能够在生产和操控方面所需要的完善工作更少。另一方面，因为 DCT 需要更多的校准处理，所以它们可以不断变化以适用于不同规格和不同行驶条件的汽车。在 DCT 和 FL 中，较少的变矩器传输在控制方面面临的一个挑战显示在图 4 中。具有阻尼传动系统的短暂变化，比如说转换过程，能够触发传动系统不良震荡，正如明显的输出转矩跟踪。 图 3 离合器溢流 对升挡 的影响 在摩擦启动（单向离合器）的传输中，没有液力变矩器使得液压传动系统没有阻尼，由此带来许多控制方面的挑战，包括汽车启动时驾驶员的感觉，以及在转换和模拟过程中的阻尼情形。不使用昂贵的扭矩或压力传感器，操控一台具有模拟变矩器的离合器是一个重大挑战。而对于液压离合器和磁流变液离合器实现的可能性，研究人员已经进行了调查研究。 传动比连续变化的无级变速器（ CVT）使得发动机能够在很大的速度和承载范围内运转，而不受车辆的速度和承载要求的限制 4。此功能允许发动机能够不受车辆速度的影响 ，而在最佳的范围内运转以实现最大限度地提高燃油利用率。市场上已经出现了不同种类的无级变速器。皮带和链传动的无级变速器使用液压活塞来保证绳轮在变速器中的地位和投入产出比。主要的控制挑战是在力求用快速的比例控制实现最大限度地提高燃油经济性的同时，如何保持最佳的加紧力去防止打滑。环形牵引驱动变速器（ TCVT）已经被许多制造商视为链或带式无级变速器的理想的替代品。环形牵引驱动变速器能够提供更大的扭矩和更快的比例变化能力。一个半环形的无级变速器在开环运作的情况下 图 4 受控 阻尼上 移后 的 效果 是不稳定的，从而需要一个速比控制系统 5。此外，当无级变速器采用齿轮传动中性的概念时，它就不再需要启动装置，例如液力变矩器和打滑离合器。在齿轮中性传动时，速比控制变得不足，从而需要对输出力矩进行控制。在环形牵引驱动变速器中，控制方面的挑战凸显在 6-7。 电动无级变速器（ EVT）最近在市场上已经出现了。使用具有行星齿轮装置的电动机械，即电动机 /发电机，它的优点包括灵活性，可控性和更好的性能。通过探索行星齿轮传动方式和与在步传输中类似的转变原则尽最大的努力来扩大速比范围。这些设计，一般来说， 是相当复杂的工程，因为它们要涉及许多的行星齿轮装置和离合器。精心的控制计划必须确保相应的转换原则和避免在转换期间输出端扭矩的突然变化 8-9。这种控制算法将最终决定司机感知混合动力汽车的性能如何，特别是当车辆在电动机和发动机之间来回切换时他们是否能准确感觉到。在传统的内燃机逐渐被燃料电池推进系统取代之前，混合动力汽车可能只是一个权宜之计。在燃料电池汽车中，电轮毂电机内可完全消除对变速器的需要和改变未来的主导技术 10。 2.传输控制算法和硬件发展 具有矫正变量的查询表广泛应用于汽车变速器控制中。随着功 能和电子部件的增加，系统校准的复杂性上升很快。这不仅是由传输中的电子控制造成的，而且与发动机和其它部件在动力传动系统中的协调性也有关系。例如，随着自动变速器中齿轮传动比数的增加，实现在任何行驶条件下平稳转换的校正变量的数量就会迅速上升。为了大大降低开发时间，提高性能，在校正过程中，自动化和系统化的方法是必需要的。首先，对自动调节过程进行研究使其在很少或没有人为干扰的条件下能够自动校正变速器。研究人员开发了一套自动化的工具装备用来校正在无人干涉条件下的汽车动力总成 11。为了标定 GDI 发动机，研究人员开发了 一种自适应网络设计实验（ DOE）方法 12。这种方法能为具有不规则形状的操作区域的非线性系统进行高效的实验设计。同样的方法也可以应用于汽车传输校准。其次，人们提出了将控制模型视为一个推动者的想法，目的在于减少校准变量数，以及校准的时间和精力。然而，环境的不确定性和操作范围的广泛是系统稳定性方面的一个主要挑战。传输温度可以在 40 摄氏度到 150 摄氏度之间变化，这反过来又影响到自动变速器流体的属性。从车辆完全停下来到高速大负荷的运转，这种大范围变化的操作需要精确的模型和高宽带控制。参考文献 13介绍了确定一套 线性模型的步骤和相关的自动变速器液力变矩器的非建模动力学，及应用稳劲的控制设计以达到预期的性能。详细的对于控制转换阶段变速器模型惯性的开发步骤呈现在文献 14中。基于这些模型，可以对稳健的控制进行设计，使其不用考虑发动机负荷、自动传动流体的粘度，以达到理想的转向性能。为了实现自动手动变速器中离合器的控制，研究人员对变结构控制（ VSC）进行了研究 15。结果表明，变结构控制能够在未知的环境下保持系统的稳定。第三，自适应学习控制的开发是为了满足不确定的环境和不同的驾驶模式的要求。人工神经网络（ ANN）的使用 是用来模拟采用黑盒技术的汽车动力总成 16。输入和输出数据是用来训练神经网络，使其能仿效变速器及它的子系统的功能。这种方法的特点是它不仅可以模拟稳态运作，还可以模拟动态 /瞬态系统的运作。这种方法的主要优点包括使用实时车辆数据的在线培训、自适应校正或控制能力。 随着变速器速比数的增加，换挡规律也变得更加复杂了。由于传统的换挡规律只考虑到用汽车的速度和节气门开度来确定换挡位置，所以换挡复杂已经成为在某些情况下，如丘陵地形条件，的关注焦点。例如，在蜿蜒上坡的道路上行驶时，驾驶员在进入曲线行驶之前要释放加速踏板来 降低车速，而传统的换挡规律为了响应油门的变化可能会换高速挡。但蜿蜒路段过后，司机需要踩加速踏板提高车速和执行换低挡操作。同样在下坡行驶时，一旦节气门开度减小，传统的换挡系统会挂高挡，结果降低了发动机制动性能。由于一些因素，如道路等级、转向角度、汽车加速等，既能满足客户要求，又有良好的燃油经济性的灵活的换挡系统必须得到开发研究。采用模糊集和神经网络技术来避免换挡繁杂已经在以往的文献 17-18中得到了探讨。大多数呈现在文献中的自适应换挡点算法需要搜集大量车辆的信息和车辆行驶的道路坡度。这些文献很少提供可靠的 质量估计算法。如果有大量适用的信息，那么道路等级的估计直截了当。近来，汽车导航系统用于提供一些在换挡过程中关于道路形状和条件的预览信息 19。针对换挡系统的近期工作增加了模糊逻辑系统的反馈研究，实时更新隶属函数以更好地满足不同的驾驶模式。它们也拓展了一些功能，不仅仅包括 AT 也包括 AMT、 DCT 和CVT。总结一般结构换挡规律的框图方法如图 5 所示。 为了满足对计算能力、遥感和驱动能力不断增加的需求，变速器控制硬件已经发生了许多变化。这些变化包括三个方面的复杂性：遥感水平、驱动水平和系统水平。在遥感水平方面，新 的遥感技术用于要么提高目前硬件的性能和效率，要么用于启动新的驱动技术。压力调节器和温度传感器在目前生产的变速器上比较适用。为了提高变速器的性能，压力传感器和扭矩传感器是必不可少的。将这些传感器引用到生产单元的主要挑 战是生产成本和耐用性。圧阻式半导体压力传感器是汽车应用水平的评价标准21。它 图 5 齿轮移位调度算法 框图 宣称测量可达到 3.5 兆帕，在满刻度的百分之一范围左右。早期的扭矩传感器的研究可以追溯到八十年代初期，那时研究人员 22为自动变速器研究了一种非接触式微型扭矩传感器 。最近许多研究人员对磁扭矩传感器进行了研究 23-24。把材料应力转化成磁性能的变化的反磁现象用于测量传输的扭矩。为了克服变速器中的恶劣环境，特种涂料技术已经得到开发以保护传感器部件。带有扭矩传感器的离合器盘被提议用在汽车上 25。安装在离合器盘上的传感器元件用于实现精确可靠的测量。在驱动级中，电磁阀控制技术的研究在于改善液压系统的可控性和灵活性。对于离合器驱动而言，为了获得更好的可控性，变分压螺线管（ VBS）电磁阀现在普遍取代了脉冲宽度调制（ PWM）阀。然而， VBS 的阀门会因为温度变化出现滞后和变化的 问题。系统辨识理论 26用于对比例控制电磁阀进行分析建模。报告的结论是该阀的带宽受到螺线管电磁部分带宽的限制。为了进一步提高系统性能，快速、精确的气门驱动装置是必不可少的。一种关于开关阀 /执行器旋转的新概念建议处理在不到 5 毫秒的响应时间里大于 10 行 /毫米的流量。这种概念的主要特点是这种阀有一个单级结构，却有两级功能。可选的离合器传动技术也被提倡去取代电动液压执行器自动变速器，以改善燃油经济性和性能。许多研究人员 28已经对电动驱动离合器进行了研究。这种机电执行器的主要挑战是车内的低功率密度和合适的电力。 通常扩大电机的转矩能力需要某种齿轮传动。研究人员已经开发了一些用于离合器驱动装置的智能材料。在自动变速器中使用电流（ ER）流体传动离合器的可行性已经得到了证实，电流流体的理想性能的提出也是为了以后的研究 29。磁粉离合器作为一种启动离合器被用在 CVT上 30。文献 31讨论了磁流 MR液压离合器的潜在用途。在系统级中，有一种将电子控制从乘客车厢转移到传动箱，甚至整合齿轮箱内部的电子控制以减少成本和提高性能和质量 32-33。最近创造出了一种叫机电一体化传输的新术语，用来解释本身具有传输装置的电子控 制的整合。除了成本和质量效益之外，这一方法将使装配线上传输装置的测试和校准成为可能。为启用变速箱集成电子产品，新型的电子集成和封装技术也得到了研究，以克服变速箱内的恶劣环境 35。 3.结论 为了实现最大的燃油经济性并提高优越的性能，在控制软件 /算法和硬件方面的研究和开发对于自动变速器来说都是必不可少的。随着增强的功能和软件、硬件日益增加的复杂性，系统整合是变速器成功发展的关键。 参考文献 1 Wagner, G., “Application of Transmission Systems for Different Driveline Configurations in Passenger Cars”, SAE Technical Paper 2001-01-0882. 2 Hebbale, K.V. and Kao, C.-K., Adaptive Controlof Shifts in Automatic Transmissions, Proceedings of the 1995 ASME International Mechanical Eng ineering Congress and Exposition, San Francisco, CA, 1995. 3 Kao, C. K., Smith, A. L. and Usoro, P. B., “Fuel Economy and Performance Potential of a Five-Speed 4T60-E Starting Clutch Automatic Transmission Vehicle”, SAE Technical Paper 2003-01-0246. 4 Kluger, M. and Fussner, D., “An Overview of Current CVT Mechanisms, Forces and Efficiencies”, SAE Technical Paper 970688. 5 Raghavan, M. and Raghavan, S., Kinematic and dynamic analysis of the half-toroidal traction drive variator, Proceedings of the 2002 Global Powertrain Congress, Detroit, MI, September 24-27, 2002. 6 Tanaka, H. and Eguchi, M., “ Stability of a Speed Ratio Control Servo-Mechanism for a Half-Toroidal Traction Drive CVT,” JSME International Journal, Series C, Vol. 36, No. 1, 1993. 7 Hebbale, K.V., and Carpenter, M.E., Control of the Geared Neutral Point in a Traction Drive CVT, Proceedings of the 2003 American Control Conference, Denver, CO, 2003. 8 Tsai, L. W., Schultz, G., A Motor-Integrated Parallel Hybrid Transmission, Journal of Mechanical Design, Transactions of the ASME, Vol. 126, September 2004. 9 Ai, X., Mohr, T., and Anderson, S., An Electro-Mechanical Infinitely Variable Speed Transmission, SAE Technical Paper 2004-01-0354. 10Burns, L., McCormick, B., and Borroni-Bird, C., Vehicle of Change How fuel-cell cars could be the catalyst for a cleaner tomorrow, Scientific American, October 2002. 11Furry, S. and Kainz, J., “Rapid Algorithm Development Tools Applied to Engine Management Systems”, SAE Technical Paper 980799. 12Stuhler, H., Kruse, T., Stuber, A., Gschweitl, Piock, W., Pfluegl, H. and Lick, P., “Automated Model Based GDI Engine Calibration Adap