Baumüller has developed a compact drive system for multifunctional municipal vehicles
Baumüller has developed a compact drive system with very high energy efficiency for fully electric municipal vehicles. The vehicle is designed for speeds of up to 80 km/h and has a range of up to 100 kilometers. The end-result of this collaboration with other companies is an emission-free, environmentally friendly, low-noise, multifunctional municipal vehicle. It can be used with interchangeable accessories for a wide array of municipal cleaning and maintenance activities, e.g. as a road sweeper, snowplow or loader.
This joint development project with the companies Cosyst Control Systems GmbH, bLz - Bayerisches Laserzentrum GmbH, Polyplast Sander GmbH and SMS Engineering GmbH was supported by sponsorship from the Bavarian State Ministry for Business and Media, Energy and Technology. The project owner is Bayern Innovativ.
Electric Axle for Rear-Whell and Four-Wheel Drive
Baumüller’s compact drive system consists of two fully electric drives, each mounted on the vehicle’s rear axle. Alternatively, instead of a rear-wheel drive, a fourwheel drive can be deployed with four drive systems. Each drive system consists of a Baumüller DSA synchronous axial flow motor with integrated converter, power electronics plus planetary gears and has been designed specifically for this grant-assisted project.
The planetary gears are located in the wheel rim and are directly connected to the drive system. This has the advantage that there are lower transmission losses because there is no need for an additional drive train, such as a cardan shaft, drive shaft or differential. Other benefits of the compact drive system include greater versatility and improved driving comfort. The drive also has excellent overload capabilities, for instance gradients of up to 18 percent can be handled quite easily.
The key feature in the robust, re-designed DSA motor, with a nominal power of 18kW, is the winding switchover. This enables the municipal vehicle to automatically change gears from working speed to high-speed without losing any efficiency. This switchover allows different torque values and speeds to be achieved, with automatic adjustments depending on the application being made via the motor controller developed by Baumüller. This means that in the first gear, at working speed, e.g. for sweeping or mowing operations, double the nominal torque can be achieved at just half the speed.
This gear is used for speeds up to 40 km/h. The power source is not burdened with large currents, which enables a significantly larger range and longer operating duration than previously. In second gear, the highspeed gear, speeds of up to 80 km/h can be achieved. Despite the higher speed, the power requirements correlate to those for the first gear. Efficiency also remains very high, thus enabling both a significantly larger range and a longer operating duration.
The installation space for this electric axle (motor and converter) has been optimally adjusted to suit the installation conditions in the vehicle, with small dimensions of just 414 mm length and 300 mm diameter.
Comprehensive Safety Concept
For fieldbus communication and thus the connection to the control unit, Baumüller uses CANopen for this purely electric vehicle. In addition, there is reciprocal monitoring of both drive controllers in the b maXX series as well as all important safety measures affecting the drive.
Energy Recovery Included
The fully electric municipal vehicle is 3.4 meters long, 1.4 meters wide and is able to generate energy when braking or driving downhill. This energy is then fed back into the three battery modules each with 8.5 kWh. This further enhances the range and energy balance. The vehicle has a range of approximately 100 kilometers.
Plenty of Expertise in the E-Mobility Sector
Baumüller is exploiting its many decades of experience in developing motors and producing electric engines; for over ten years it has been supplying energyefficient components and comprehensive solutions for hybrid and fully electric drive systems. These lownoise, low-emission drive solutions are being used in hybrid agricultural machinery, tracked vehicles and fully electric city buses and municipal vehicles, to name just a few examples.