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Volvo Buses B5L – Hybrid

[ Saturday, May 8th, 2010 | by automotiveroom | under CAR, Volvo ]

volvo b5l hybrid double dec Volvo Buses B5L – Hybrid

drivelines on our are an important step to reduce fuel consumption and, consequently, the emission of carbon dioxide. Whilst hybrid technology – combining energy from two power sources – has existed for a long time, it has not previously been commercially viable.

However, the launch of our hybrid bus signals a generation shift. With a hybrid solution that is largely based on standard products and with fuel savings of up to 30%, customers can achieve payback on the incremental capital costs far quicker than previously was the case.

The technology also lowers the exhaust emissions by up to 50%, and noise levels substantially.

The Driveline Elements

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The key elements of the Hybrid are:

•    D5E 4 cylinder 5 litre Volvo diesel engine to Euro 5 emissions level with SCR exhaust aftertreatment
•    Volvo ISAM Integrated Starter Alternator Motor electric machine to provide parallel operation of diesel and electric power
•    Volvo I-Shift 12 speed automatic transmission
•    Lithium-Ion Battery Energy Storage System, rated at 600 Volts, water cooled
•    Electrically-driven Air Compressor, Hydraulic Pumps and AC/Air Chill compressor

The chassis module is very similar to that of the existing Volvo B9TL Double Deck.  Many proven Volvo components can be identified from the front end through to the drive axle, driveline and rear suspension for maximum service commonality.

The Hybrid Vehicle Management System includes the software “brain” of the vehicle and this interfaces with the regular Volvo diagnostic functions.

The ISAM unit is integrated in the clutch housing between the diesel engine and the gearbox, this allows for combining the power inputs of both motors in the simplest way. In a parallel hybrid, the vehicle can be driven by both the diesel engine or the electric motor or any combination of the two.

This means that the diesel engine can be downsized from that of a conventional bus, and at the same time the electric motor can also be smaller, because it does not have to provide the maximum power level on its own. Combining the two sources provides the power needed to climb steeper hills or for maximum acceleration.

The strategy for managing the hybrid system prioritises fuel efficiency and therefore reduced emissions of carbon dioxide. At the same time, the range of gear ratios in the transmission means that the diesel engine can operate in its most efficient range more of the time.

It is also possible to operate in purely electric mode – at bus stops for example – to minimise local air quality emissions in sensitive areas: the bus can pull away from the bus stop in quiet electric mode and engage diesel power as the system requires for maintaining battery charge. Normal braking can drive the ISAM unit in alternator mode to achieve regenerative braking/energy recovery to charge the battery and this is another key step to reduce fuel consumption.

Driving the auxiliary systems with electric motors also saves energy because the load can be delivered when needed most – as with power steering where the most power is needed at low speeds so matching the demand avoids wasteful operation.

There’s no better way to test the realities of hybrid technology than with public transport, where significant reductions in fuel consumption and emissions are not just desirable, but a commercial necessity. London got a little greener this week with the delivery of six new Volvo hybrid double-decker buses to Arriva London. The new buses are powered by Volvo’s parallel hybrid which, used on bus routes in Gothenburg, Sweden, has delivered fuel savings of 30%.