Shanghai orders 1100 buses, for the first time with automatic transmissions
ZF supplies three quarters of these automatic transmissions
Optimal combination of ZF's automatic transmission EcoLife and the new TopoDyn Life control software
The individual power requirement is determined depending on the route profile and all driving resistances
Higher torque, extended service life, lower consumption

ZF-Ecolife

More than 800 new city buses which will be used at the EXPO 2010 in Shanghai, feature ZF transmissions. On board: The tried and tested combination of the Ecomat transmission with the inte-grated shift strategy TopoDyn as well as the latest ZF transmis-sion generation for city buses, ZF EcoLife, which ensures addi-tional fuel economy with the new TopoDyn Life control software.

In the run-up to the EXPO 2010 in Shanghai, public passenger transport is being modernized in the most important Chinese in-dustrial city. To this end, the city has ordered 1,100 new city buses, for the first time with automatic transmissions, roughly three quar-ters of which will feature economical ZF transmissions. The latest transmission generation for city buses is also used for the first time in China: 100 city buses of the Volvo BXR type are equipped with the ZF EcoLife 6-speed automatic transmission which is available off-the-shelf with the new, intelligent TopoDyn Life control soft-ware. Volvo developed the 10.5 meters long vehicles especially for the service in Chinese metropolises. The combination of the ZF automatic transmission EcoLife and the continuously variable shift strategy TopoDyn Life by ZF is a real breakthrough in terms of fuel economy. Together with the ZF Ecomat automatic transmission, the predecessor generation TopoDyn had already led to fuel sav-ings of up to 19 percent compared to Ecomat transmissions with-out TopoDyn. The reason: Information about the topographical route profile is considered when selecting the optimum shifting point. The further development of the intelligent TopoDyn Life software now considers all driving resistances in addition to the topography. Combined with the latest automatic transmission gen-eration for buses, ZF EcoLife, another five percent fuel can be saved. Only the future hybrid version of the ZF EcoLife transmis-sion will even be more economical. In the parallel hybrid configu-rations, an electric motor is installed exactly in the previous instal-lation space of the torque converter. This hybrid module will have a power of 120 kW.

New damper, more torque and an improved cooling concept

And all this with considerably more power: Compared with con-ventional powershift transmissions, the ZF EcoLife transmits 25 percent more torque and has been designed for a considerably longer service life. The 6-speed automatic transmission, which is designed for torques of up to 2,000 Nm, generates better accelera-tion values at lower engine speeds thanks to the new torque con-verter. A torsional damper fits into the installation space of the torque converter. This means that the lock-up clutch can close more quickly and reduce the hydraulic – most fuel-intensive – part of the starting process. The significantly more powerful Citybus re-tarder supports braking and also contributes to the cooling concept by means of a heat exchanger – in addition to the oil cooler which is integrated in the transmission. Thus, the new transmission can work even at oil sump temperatures of up to 120 degrees Celsius, which is particularly important with regard to the modern Euro 5 standard diesel engines. Thanks to the improved heat economy, oil change intervals and service life are also extended, the wear-free retarder can brake more powerfully and longer. The transmission is even more reliable and easier to service; therefore, it is also more economical in operation.

System optimization as a target

During the development of the EcoLife, ZF engineers also paid at-tention to system optimization. For example, the electronic control unit with a new design and considerably increased performance is now located laterally on the transmission. The advantage of this place is the constantly low temperature level because it is located directly next to the oil cooler. The complex wiring harnesses was simplified dramatically, and it is easier to install thanks to fewer interfaces. This means significantly simplified handling for vehicle manufacturers and customer service.

Topography-dependent, continuously variable shifting

The transmission adapts the shifting characteristics to the respec-tive route profile during travel - thanks to TopoDyn Life, a control software developed specifically for EcoLife. The shift points are calculated considering the topography, current load and accelera-tion values as well as variable driving resistances, such as road sur-face or corner angles. When the bus is operated in the city, TopoDyn Life automatically selects the most economical shifting characteristics. Once the terrain becomes steeper, the software smoothly adjusts the selection of shift points to the current gradi-ent in a continuously variable manner. This ensures that the en-gine runs in the ideal, that is the most economical operating mode at every point of the route. In contrast to its predecessor, TopoDyn Life no longer has various shift programs but only one single con-tinuously variable shift program. The benefit: The transmission does not change gears at shift points which are determined by the currently active program but calculates the power requirements independently and changes gears whenever the driving situation requires.

No additional components required

In contrast to GPS-based or sensor-based systems, TopoDyn Life by ZF requires no additional components and provides the necessary information even in unknown terrain where GPS is not available. As the software does not require any interference by the driver, the driver does not have to be trained for this function.

Source : www.zf.com

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