Servos synchronisation brings ultra-smooth transmission

　　An example of a gear shift from the third to fourth gear

　　Problems with acceleration

　　Despite this promise, the AMT was a failure. Diagram 1 illustrates why. It shows the acceleration of a vehicle with an AMT (model year 2001). The acceleration disappears for 900 milliseconds. As the gear shift is initiated by a computer, the driver might find that the torque disappears when the driver really needs it. Furthermore, the acceleration after the gear shift is far less than before the gear shift. To approach the comfortable ride of a present day AT transmission, an AMT should change gear so quickly that the passengers do not even feel it, and it should have the same acceleration before and after the gear shift.

　　One problem with fast gear shifts is that the drive shafts that connect the vehicle tyres to the transmission are torsionally weak. The energy stored in their flexing creates considerable forces on the gear box components and this has to be released before the current gear can be disconnected. A similar problem is caused by the torque ripple damping device between the engine and the input shaft of the gear box. While the device is essential to reduce noide and vibrations, during acceleration it stores considerable energy that has to be released from the initial gear before a gear change.

　　The Strigear hybrid system

　　The hardware used in the Strigear hybrid system offers a solution to both of thaese problems. The Strigear topology, designed for low fuel consumption, also gives an additional benefit in the form of very fast gear shifts. By using the two electric machines in the Strigear as servo motors during the gear shift, a very fast and smooth shift can be achieved. This transmission has been named Servo Synchronized Manual Transmission (SSMT).

　　Strigear has an internal combustion engine and two electric machines. One of these, the engine side motor (EM) is closely connected to the engine and may be assembled directly on the flywheel. The other machine, the tyre side motor (TM) is connected to the input shaft of the gearbox. The internal combustion engine and the EM are connected to the gear box and the TM over a connection device that normally acts as a one way clutch, similar to the free-wheeling of a bicycle.

　　The acceleration of a vehicle with an AMT (model year 2001) disqppears for 900 milliseconds

　　Diagram 2 shows an example of a gear shift from the third to foruth gear. In the figure, all speeds are shown in rad/s and all torques are shown in Nm. The colours used in the diagram correspond to the same part in the inlaid component schematic.

　　How the system works

　　The system shown connects the TM machine with theengine over a one way clutch. Initially, the torque over the torque (dark red) which in the initial steady state gives the same torque over the damper (green). The engine side motor runs idle. The battery power used for the acceleration is feeding the TM motor.

　　The gear shift is initiated by a short negative torque form the EM motor (red), a longer negative torque from the TM motor (pink) anda reduction of the thermal engine torque (plum). These combined torque changes will cause the tension over the damper (green) to shut up and then swing back. At t=31ms it has gone down to zero, and the one way clutch will open and will remain open during the interval marked as “Free Wheeling”. During this period, there are two temporarily independent systems, each having an electric motor with high bandwidth.

　　One of the tasks for the EM machine is to force the engine speed to a suitable value before the fourth gear is engaged at t=71ms. When the fourth gear has been engaged, a small increase in the engine speed will cause it to run faster than the TM machine, thus causing the one way clutch to lock at t=81ms and the torque over the damper (green) to increase, thus enabling torque from the engine and EM machine to reach the tyres.

　　During the time from t=35 to t=71, the task for the TM machine is to force itself and the gear box input shaft to fit the speed to speed of the fourth gear on the gear box output shaft.

　　By small adjustment of the braking torque, the servo system can arrange that the two gear box shafts will be in a position where the spline ring for the forthcoming fourth gear can be directly moved to engage the fourth gear. After engaging the fourth gear, the two electric motors use algorithms to cause a fast build up of the tyre torque (yellow) and the damper torque (green). The interruption of the acceleration is some 67ms, and the gear change. The gear shift should be unnoticeable.

　　参考译文：

　　几年前，自动手动一体式变速器AMT被认为将代替传统的自动变速箱，其中的手动控制销由电控执行单元代替，从而具有更好的效率和更低的油耗。和传统的自动变速器AT一样，AMT技术将不需要驾驶员操纵换挡。和传统的手动变速器相比，它的油耗更低，尽管两者在机械结构上时相同的。当驾驶员心不在焉地驾驶一辆装有自动变速器的汽车时，可能在低档持续跑上10分钟；而对于装有AMT的汽车，其控制电脑将时刻通过传感器感知路况，适时的换挡以保持最高的效率。

　　一个从三档换到四档的例子

　　加速过程的难题

　　尽管预言了AMT将代替AT，但是AMT技术一直没有投入使用，原因见图一。它描述了装有AMT的汽车的加速过程。在换挡过程中，有900毫秒的时间没有加速度。由于换挡是由电脑控制执行，驾驶员在需要加速的时候可能发现扭矩消失。此外，换挡后加速度远远低于换挡前。为了具有现有AT变速器系统轻松驾驶的长处，AMT系统应该换挡更快，以至于乘员感觉不到，而且保证换挡前后加速度不变。

　　实现快速换挡困难的一个原因是连接汽车轮胎和变速器的传动轴扭转刚度不够。自身扭转变形储存的能量会对变速箱零部件产生一定的作用力，这些能量必须在摘除现有档位之前释放。实现快速换挡的另一个关键是扭矩波动阻尼装置，它位于发动机和齿轮箱输入轴之间。该装置能有效地减少振动噪声，但在加速过程中，它存储一定量的能量，这些能量必须在换挡前从初始档位中释放。

　　Strigear混合动力系统

　　Strigear混合动力系统中使用的硬件提供了解决上述两个问题的可能。该Strigear布局。不仅为降低油耗而设计，还有益于快速换挡。在换挡过程中，通过Strigear中的两个电子装置作为伺服电机，就能实现快速平稳的换挡。这种变速器已被称作伺服同步手动变速器SSMT。

　　Strigear由一个内燃机和两个电子装置组成。其中一个电子装置称作发动机侧的电机，它的发动机紧凑连接，可以直接装配在飞轮上。另一个电子装置称作轮胎侧的电机，它连接在变速箱的输入轴。内燃机和EM通过一个连接装置连接在变速箱和TM上，该装置一般情况下作为一个单向离合器使用，和自行车的飞轮相似。

　　装了AMT的汽车（2001年的车型）的加速度消失了900毫秒

　　图示2阐述了一个从三档换到四档的例子，在图中，所有的速度的单位都是rad/s，扭矩的单位都是显示Nm。图解中的零部件使用的颜色和图中内嵌部件示意图的颜色对应。

　　系统式如何工作

　　如图，系统通过一个单向离合器连接TM电机与发动机。最初，作用于轮胎的扭矩约是780Nm。它来自发动机扭矩，初始稳定状态下扭矩与作用于阻尼器的扭矩相同。发动机侧的电机怠速运转。其本来用于加速的电源能量此时用于补偿TM。

　　换挡是由EM上的瞬时负扭矩信号和TM上的较长负扭矩信号共同触发，此组合的扭矩信号变化会是阻尼器的变形恢复，然后振荡回去。在t=31ms，它的下降为零，单向离合器处于打开状态，在此期间，出现了两个暂时对立的系统，每一个系统都有电动马达和高带宽。EM的任务之一就是挂上四档之前调节发动机转速到一个合适的值。当四档挂上后，发动机转速的小幅增加会导致EM转得比TM更快，从而使单向离合器锁止，同时阻尼器上的扭矩增加，此后发动机和EM上的扭矩将传递到轮胎。

　　在t=35ms和t=71ms之间的时段，TM的任务是使其自身和变速箱输入轴的转速与四档时变速箱输出轴的转速相同。

　　通过小幅度的调整制动力矩，该伺服系统能够使变速箱的输入输出轴在适当位置，待扣住四档齿轮的花键环可直接与四档齿轮配合，在配合上四档齿轮后，两个电子装置通过一定得算法使轮胎扭矩和阻尼器扭矩快速提高，加速中断的时间约为67ms，而且换挡前后的加速度相同，因此，换挡几乎感觉不到。