Page - 22 - in Hybrid Electric Vehicles

Figure 15. Schematic view of Komatsu—HB215 LC-1 hybrid excavator [126]. The attempt at classification in the present work is based on the specific HF defined in Section 4, taking into account the data sheets of the vehicles. Table 4 shows the hybridization factors for work machines, calculated by using Eq. (4) [22] and considering the effect of a hybrid elec- tric driveline and hybrid electric loading/working functions. 6. Trends and conclusions This study focused on the electrification of work vehicles, such as agricultural machineries, which is still in the research and development stage. Similarly to HEVs, the main design issue in HACMs is controlling the energy transfer from the sources to the loads with minimum loss of energy, which is dependent on the driving and working cycles. Compared with auto- mobiles, the introduction of electric drives in tractors would allow expanded functionalities because agricultural machines have a large variety of functional drives. Main differences in requirements, working cycles, and proposed hybrid architectures between HEV and HACM were determined along the present study, focusing on a specific hybridiza- tion factor for working vehicles that consider both the driving and the loading electrification. The hybridization factor for working vehicles is introduced in order to classify and compare the different hybrid solutions proposed by main manufactures taking into account differ- ent architectural choices. Moreover, the claimed increasing of efficiency due to the power train electrification is reported and listed in terms of fuel consumption reduction. Taking into account a large variety of architectural hybrid solution, it has been proven a good correlation between the hybridization factor and the fuel efficiency as a general trend in benefit of hybrid electrification of working machine. Hybrid Electric Vehicles22