|Urbino 18 DIWAhybrid system layout. Click to enlarge.|
Solaris Bus & Coach and Voith Turbo are introducing a new Urbino hybrid bus—the Urbino 18 DIWAhybrid articulated city bus—equipped with a Voith parallel DIWAhybrid system (earlier post). Solaris currently offers an Urbino 18 Allison hybrid, an Urbino 18 Vossloh Kiepe hybrid, and an Urbino 12 hybrid.
The new Solaris Urbino 18 DIWAhybrid features a 150 kW electric motor supporting the downsized diesel engine. Energy is stored in Maxwell ultracapacitors, resulting in reduced fuel consumption and lower wear and tear. Field testing by Bochum-Gelsenkirchener Straßenbahnen AG is under way.
|Solaris Urbino 18 hybrid. Click to enlarge.|
The new Voith Turbo hybrid drive is based on DIWA automatic gearboxes, which are used around the world, and Voith’s long-standing experience in developing electric drive systems.
In the DIWAhybrid system, an asynchronous electric motor supports the diesel engine when pulling away from stops and accelerating. During braking, the asynchronous motor acts as a generator and primary retarder, complementing the DIWA secondary retarder. This allows electric energy to be recuperated, reducing the use of the driving brake, minimizing brake wear and tear and lowering resulting particulate emission.
Energy recaptured during braking is stored in a supercapacitor unit weighing 410 kg (904 lbs). Its five 125 V modules have a total storage capacity of 0.5 kWh. Supercapacitors as well as the Voith inverter are roof-mounted, eliminating passenger cabin intrusion.
The DIWAhybrid system is designed for up to 290 kW power input and a maximum input torque of 1,600 Nm (1,180 lb-ft). At 150 kW electric traction power, the DIWAhybrid system reduces the load of the diesel engine enough for the latter to be substantially smaller than on conventional diesel buses. The Urbino 18 DIWAhybrid uses a 6.7-liter, 181 kW (246 PS) Cummins ISB6.7EV 250H diesel engine meeting the EEV emissions standard.
Thanks to the use of a smaller diesel engine, the weight of the entire bus is just 600 kg above that of a diesel-powered Urbino 18. The passenger cabin layout is identical to the conventional version, with passenger capacity only marginally affected. The Urbino 18 DIWAhybrid has 51 seats and a room for 161 passengers total.
The Urbino 18 DIWAhybrid was developed with support from the German Federal Ministry of Transport, Building and Urban Development and NOW GmbH National Organization Hydrogen and Fuel Cell Technology. As part of the Rhein-Ruhr Electric Mobility Model Region, a pre-production vehicle entered service with Bochum-Gelsenkirchener Straßenbahnen AG (BOGESTRA AG) in mid-February 2011. After six months of field testing, the first production vehicles for BOGESTRA AG and other German operators will follow in summer 2011.
BOGESTRA AG has successfully used climate-friendly drive technology since early 2008, when it took delivery of the first hybrid bus in North Rhine-Westphalia. Three more followed in 2010 and when the new Urbino 18 DIWAhybrid arrive in mid-2011, the company´s fleet will increase to 15 hybrid buses.