Zeroshift move up a gear with HBM data logging

Zeroshift,一家总部位于英国的公司,专门致力于开发传输技术,开发了一套可以测量瞬间传动比的系统 . Zeroshift 采用了 HBM 的数据采集系统和 MGCplus 和 catman®Easy 测量软件.

为了使系统有广泛的应用,大量的动力传动系统参数需要在变档时进行密切关注; 如发动机和车辆速度,传动扭矩,驱动位置以及离合器和踏板位置等.

于是 Zeroshift 采用了多通道数据采集系统 MGCs. 通过于原始厂商合作, Zeroshift 可以进入车辆 CAN (Controller Area Network) 总线, 可以读取 CAN 通道 数据.   

Zeroshifts 的首席工程师 Adam Huckstep 说, ‘Zeroshift, 顾名思义,我们可以瞬间改变齿轮. 因此我们的数据记录器需要极快地采集数据并在换挡时可以捕获发动机和变速系统的扭矩变化,并跟踪驱动系统的位置. 换挡往往只有几个毫秒,因此我们需要达到上千采样频率的数据采集系统来记录变化“

Business Development Manager, Ray Heath, explains that they also make great use of the PC card data logging function.
‘Our test vehicles are regularly driven by customers and potential clients who don’t want to be starting and stopping data loggers on their test drive. However the data from different drivers and driving styles is useful for our engineers, so the PC card data storage function allows us to trigger the data logger for example on key-on, or on an engine speed threshold, and capture all the data of the drive.’

The future of transmission technology

The Zeroshift principle is relatively simple in concept: the new gear is engaged whilst the previous gear is still driving, eliminating the break in torque (head nod) experienced in conventional manual and automated manual transmissions during a gearshift. As the new gear takes up the drive the previous gear is automatically disengaged, leaving the vehicle to continue driving in the new gear.
Figure 1 illustrates the arrangement of bullets and dogs and gears. The blue and red bullets appear identical, however their ramp and engagement faces point in opposite directions providing a bullet face on either side of the dog teeth and hence transmitting torque from the gear mesh to the hub via either the driven or overrun set of bullets.

Shift sequence

Figure 2 illustrates the process of making a ‘Zeroshift’ (shifting gear without a delay in applied torque to the driven wheels). An up-shift from gear one to gear two is detailed below, and illustrates how the geometry of each set of bullets makes it possible to achieve a seamless gearshift.


Starting in neutral, figure 2(a) shows both sets of bullets (blue and red) positioned midway between the gear 1 and gear 2. Torque generated by the engine is transmitted to the transmission output shaft via the dog teeth. Since neither set of bullets are locked to a gear, the vehicle is in neutral. 
To select first gear, both bullet sets are moved onto gear one dog teeth via an actuator. Figure2(b) shows the blue bullets engaging onto gear one, which is driving in a clockwise direction.

The red bullets lock onto the overrun side of gear one dog teeth (figure 2c). In the event of the driver breaking, the direction of torque is reversed and instead runs in the anti-clockwise direction. In this case the red bullets will take up drive and slow the vehicle down.

Assuming the driver is accelerating and wants to change from gear 1 to gear 2, the unloaded bullets (in this case the red bullets), are free to move. The loaded bullets (blue), are locked to gear one since the retaining force (due to the torque acting on the retention angle) between the bullet face and dog tooth is greater than the axial force generated by the actuator as depicted in figure 2(d).

Gear 2 rotates with greater angular speed than gear 1 (both in the clockwise direction). As the red bullets engage onto the dog teeth the drive taken up on its bullet face pushes the hub (figure 1), at the new speed. Notice that in figure 2(e), both red and blue bullets are engaged at the same time. This is the point of Zeroshift.

Now the hub is moving at a speed dictated by gear 2, the blue bullets are overdriven and come loose from the gear 1 dog teeth (figure 2f).

The blue bullets are now free to move. Figure 2(g) shows a dog tooth on gear 1 making contact with the ramp face of the blue bullets thus firing it into position to act as the over-run gear on gear 2 (figure 2(h)). Even though both gear 1 and gear 2 are rotating in the clockwise direction, gear 1 is running slower with reference to a point on gear 2.

Notice that the red bullets are now the driven bullets (formerly the overrun bullets) and the blue bullets are the overrun bullets (formerly the driven bullets).

Seamless shifting

Figure 3 and 4 are graphs obtained by HBM data logging equipment and from simulation respectively. The smooth speed curve obtained by Zeroshift transmission is clear. Uninterrupted torque to the driven wheels allows positive acceleration through gearshifts. The simulation results on figure 4 compare the speed traces of identical cars. The car with the AMT requires a break in torque to its driven wheels and hence loses positive acceleration during the gearshift.



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