German version

Solaris Urbino 18 hybrid - second generation

In the bus industry, the technology of the Solaris Urbino 18 Hybrid bus is at the forefront of current developments. In our quest for the optimal solution, we decided to team up with General Motors-owned Allison Transmission, whose hybrid technology has been proven successful in hundreds of North American buses.

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 decided to use the hybrid system produced by Allison Transmission. Experience from the operation of several hundred hybrid buses in the United States clearly showed it to be 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 bus’s 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 178 kW (242 PS) Cummins ISBe5 250B 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 52 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 specifi cation.

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.

E^v Drive

The E^v 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 fi rst unit is responsible for the management and control of the hybrid system, while the other unit coordinates cooperation with other onboard components.

The roof with batteries and energy storage

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 effi cient Cummins ISBe5. The 6.7 litre engine has a 178 kW output and complies with the Euro 5 emissions standard. It has a maximum torque of 1005 Nm at 1500 rpm. The engine has been adapted for the use in hybrid power trains and differs from a standard specifi cation engine by its dedicated control software, adapter kit and the absence of a starter.

Dual Power Inverter Module (DPIM)

The Dual Power Inverter Module (DPIM) 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. The DPIM is oil-cooled.

Solaris Urbino 18 hybrid - second generation

Photos and text:
Solaris Bus & Coach