The Solaris Urbino 18 Hybrid is a real innovation when compared to buses with traditional diesel drive trains. To achieve the best results possible, Solaris Bus & Coach uses the hybrid system produced by Allison Transmission. Experience from the operation of more than two thousand hybrid buses in the United States
clearly shows it to be one of the most established system on the market.
The Allison hybrid system combines the power of a diesel engine with two electrical engines. Advanced control electronics ensure that the diesel engine works at optimum speed at all times. Excess power is used to charge the batteries. The hybrid system also allows the recuperation of energy during braking. This is stored in batteries and re-used for subsequent acceleration of the bus.
The diesel component of the power train is made up by a 180.5 kW Cummins engine, which has a capacity of 6.7 litres. The second element of the power train is
Allison Transmission´s EP50 hybrid system.
As in the conventionally-powered Urbino, the drive train of the Solaris Urbino 18 hybrid bus is located in an engine compartment at the rear of the bus. It powers the third axle. Up to 51 seats make the Solaris Urbino 18 Hybrid the ideal bus for demanding city services. The total capacity of the Solaris Urbino 18 Hybrid is up
to 161 passengers, depending on specification.
The hybrid power train is complemented by batteries for energy storage and a Dual Power Inverter Module. These components are placed on the roof of the vehicle.
Arrangement of components in the Solaris Urbino 18 Hybrid
EV Drive - is the central element of the hybrid drive. Blending, i.e. the combination of the torques of both engines, takes place here. The EV Drive consists of two electric engines, two synchronous clutches and three planetary gearings. Externally, the 417 kg EV Drive module resembles a traditional automatic gearbox.
Control Unit - The hybrid power train is completed two Allison Transmission 1000/2000 series control units mounted onto printed circuit boards. The first unit is responsible for the management and control of the hybrid system, while the other unit coordinates cooperation with other onboard components.
Batteries - Energy recuperated during braking is stored in dedicated roof-mounted batteries, ready to be re-used for acceleration. The batteries are charged with every braking process and therefore do not need to be charged from outside power sources. The nickel-metal hydride batteries weigh 437 kg and have a service life of up to 6 years, exact life-time depending on operation characteristics.
Diesel Engine - The diesel engine used in the power train of the Solaris Urbino 18 Hybrid is a very fuel efficient Cummins ISB. The 6.7 litre engine has a 180,5 kW output and complies with the Euro 5 or EEV emissions standard. It has a torque of 1008 Nm at 1200-1600 rpm. The engine has been adapted for the use in hybrid power trains and differs from a standard specification engine by its dedicated control software, adapter kit and the absence of a starter.
Dual Power Inverter Module (DPIM) - this is another key component of the hybrid system developed by Allison Transmission. It consists of an AC-DC rectifier and a DC-AC inverter with a combined total weight of 75 kg.