Electronically controlled damper system CDC 1XL for one axle resolves the conflict between stability and comfort
ZF is presenting a one-axle version for commercial vehicles of the Continuous Damping Control (CDC) system. It is suitable for vehicle axles with frequently differing load conditions. The technology dubbed CDC 1XL (i.e. ‘one axle’) improves comfort and increases vehicle stability. At the same time, the simplified concept leads to considerably lower system costs – ideal for city buses.
ZF’s CDC smoothly adapts the damping force to the respective driving condition, thus solving the classic conflict between comfortable-soft and safety-focused, firm chassis tuning. The electronic control unit (ECU) from ZF precisely controls the CDC dampers. In dangerous situations, the CDC straightens the damping characteristic curve in split seconds and thus significantly improves handling and safety. This system clearly reduces body movements in particular.
Simplified setup reduces costs
The CDC 1XL solution is a cost-optimized version compared with other currently available systems. ZF offers the system as a complete package – consisting of the proven CDC dampers, the integrated sensors, and control unit. As a systems supplier, ZF combines the long-term experience in the passenger car business with the expertise in the area of commercial vehicle chassis technology.
Thanks to the sensor cluster integrated into the electronics, external sensors are initially not required. As a result, the wiring and installation effort decreases considerably. At the same time, the system can be retrofitted economically in this way. The fact that only two or four CDC dampers are used in total, depending on the application, further decreases the system costs. All in all, the ZF solution is a perfect match for the highly competitive city bus sector.
Clear advantages compared to non-controlled damping
For buses, axle load changes predominantly occur on the rear axle, or on the center axle in the case of articulated buses. Here, the forces vary considerably, depending on the load and the driving events. Since chassis with conventional damping have to be designed for full payload due to safety reasons, the engineers chose a very stiff damping characteristic curve when tuning the shock absorbers. Apart from less comfort for driver and passengers, the stiff suspension also frequently damages the vehicle and sensitive cargo.
As a result of its control unit concept, which has been reduced to essential parameters, CDC 1XL proves a better and economic alternative: The system reduces the acceleration values of the vehicle superstructure by up to 30 percent and thus increases the driving comfort and handling safety, particularly when the vehicle is only partly loaded.
The upshot is a new experience for drivers and passengers alike.
The controlled suspension also leads to less wear on the vehicle and above all on the vehicle superstructures – this, in turn, reduces maintenance costs. Furthermore, the load applied on the road is reduced, thereby protecting the road surface against damage. CDC 1XL provides the ideal solution for the center axles on articulated buses.
Very good energy balance
CDC works based on the principle of "as little damping as possible and as much damping as required." This means that the system opts for a preferably soft characteristic curve. That improves the chassis' energy balance since stiff damping always comes along with an increased conversion of kinetic energy into heat which is then dissipated without using it. However, this lost energy constantly needs to be topped up again via the drive energy. The optimum damping hardness of the CDC 1XL can consequently decrease the damper-related energy loss on the rear axle by up to two thirds, which ultimately also results in a slight reduction of fuel consumption.