|Volvo hybrid bus.|
The Swedish Energy Authority is granting Volvo Buses subsidies for its continued work on developing the hybrid driveline and the hybrid technology for two bus models.
Volvo’s I-SAM (Integrated Starter, Alternator, Motor) parallel hybrid system comprises a starter motor, drive motor and alternator fit between the clutch and the I-Shift automatic transmission. It supports regenerative braking; electric launch and assist; electrification of power steering, air compressor and air conditioning; and idle avoidance. (Earlier post.)
The 70 kW (120 kW peak) electric motor delivers 400 Nm/295 lb-ft of torque (800 Nm/590 lb-ft peak). The motor is used when starting off and for acceleration to about 20 kph (12 mph). At higher speeds, the diesel engine steps in and takes over while at the same time recharging the electric motor’s batteries. Regenerative braking also recharges the batteries. Electric power is utilized when the vehicle is at a standstill, in slow-moving traffic queues and during loading and unloading.
With Volvo’s new hybrid technology, we expect to be able to reduce the fuel consumption of buses by up to 35 percent.—Edward Jobson, Environmental Manager at Volvo Buses
Volvo Buses expects to be able to sell its first hybrid buses within a few years, but notes that subsidies are required to make them commercially viable at this point.
However, we expect our hybrid buses to be much more cost-effective than the buses based on the current technology. Our customers will ultimately be able to conduct their operations without requiring extra subsidies from society. In fact, this is also a necessity if hybrid technology is to have a major impact on the market and contribute to a real reduction in carbon dioxide emissions—Edward Jobson