Abstract
In this paper a novel concept of modular swift-shift multi-speed transmission with double dual clutches is proposed, with its architecture, simulation and control strategies discussed in detail. Due to its modularity, the desired number of gear ratios can be readily realized by adding the appropriate number of modules. Further, in this design, both the underdrive and the overdrive modes are combined within one single gear train, which reduces the overall volume and weight significantly. Due to its modularity and compactness, this transmission is suitable for electric vehicles, especially commercial fleets of medium- and heavy-duty electric trucks. A proof-of-concept testbed was developed; its preliminary simulation analysis is reported here.
Highlights
The idea of using electric and hybrid technologies for medium and heavy trucks in recent years became quite popular among automotive manufacturers; one of the potential sales categories for emerging hybrid and batterypowered vehicles includes commercial delivery fleets.Currently the market of electrified trucks can be split into three categories of vehicles: delivery trucks, city trucks, and e-buses
Though the maintenance cost per km of a hybrid truck can be close to that in conventional trucks, the annual maintenance expenditure remains lower since fuel economy makes sense in these driving cycles only, the hybrid truck staying in service in such driving cycles
In 2012, one of the world leaders in transmission technology, Oerlikon Graziano, in collaboration with Vocis Driveline Control, reported the results of a case study on a two-speed system for EVs [8]. These results clearly demonstrated, as confirmed by many other research teams [9, 10], the advantages of the two-speed transmission when compared to a single-speed model used in EVs via four main characteristics: acceleration time; maximum climbing grade; maximum speed; and energy consumption
Summary
The idea of using electric and hybrid technologies for medium and heavy trucks in recent years became quite popular among automotive manufacturers; one of the potential sales categories for emerging hybrid and batterypowered vehicles includes commercial delivery fleets.Currently the market of electrified trucks can be split into three categories of vehicles: delivery trucks, city (service) trucks, and e-buses. Though the maintenance cost per km of a hybrid truck can be close to that in conventional trucks, the annual maintenance expenditure remains lower since fuel economy makes sense in these driving cycles only, the hybrid truck staying in service in such driving cycles. The gas truck in high stop-and-go usage costs more both in fuel and maintenance due to higher cost of brake service. Gas trucks do not have regeneration braking, while being subject to more intensive brake wear All these issues, along with the longer oil change intervals in hybrids (due to the engine running less), make the benefits of hybrid delivery trucks apparent. Research undertaken between 2008 and 2011 for the Purolator delivery fleet showed that the average costs of maintenance per km for both gas and hybrid trucks are close to each other (both within the range of $0.15–$0.20/km), while the maintenance cost of a hybrid is nearly 30 percent lower than that of a gas unit (app. $2700 vs. $4000)
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