Prof. Hausberger (TU Graz) presented the work program of the Institute for Internal Combustion Engines and Thermodynamics (IVT) at the TU Graz. He started with a summary of the conclusions from the 7th HDH meeting.

He then explained the development of the World Heavy Duty Hybrid Cycle (WHDHC, see page 5 [of document HDH-08-04]). Basis is the full load curve of the hybrid powerpack, which is used to denormalize the speed and load pattern of the WHTC and to calculate the power pattern over the WHTC.

Taking into consideration the powertrain losses and the (negative) braking power then results in a wheel power cycle, named WHDHC. This cycle would then be used as input cycle to the HILS modelling instead of the vehicle cycle WHVC. Advantage of this approach would be that it is independent of the vehicle design and that it uses the same power demand as the same vehicle equipped with a conventional powertrain. Another advantage is the comparability with the powerpack approach. Open issues are the definition of the full load curve for a hybrid and a possible adaptation of the driver model.

The method to calculate the WHVC weighting factors on the basis of real world data is shown on page 17 [of document HDH-08-04]. A first evaluation was done for city buses and shows a good correlation between the WHVC urban part and the HDV-CO2 city bus cycle (see page 18). Work will continue with the other HDV-CO2 cycles.

It is not suggested to include PTO loads into the proposed HILS method for pollutant emission testing, but PTO might be necessary for CO2. TU Graz will therefore elaborate inclusion of PTO load on the basis of the air conditioning system of a city bus.