Electrification of Commercial Vehicles: How Drivetrains Are Evolving to Meet the Future of an Electrified World

Susan Kuchinskas

The transition to electric vehicles is inevitable for the commercial transportation industry, driven by the imperative to reduce air pollution and the rising cost of diesel fuel. Regulation plays a key role in this. In some places, fleet operators will have no choice but to switch to EVs. Paris, Milan, Mexico City and Athens are among those with plans to ban diesel engines in city centers—and this approach will gain momentum as its viability becomes clear.

At the CTI SYMPOSIUM USA in Novi, Mich., held on May 13 to 16, manufacturers and suppliers will present their future visions and current initiatives on the road to electrification of commercial vehicles. We’ll see several approaches, including strong (P2) hybrid drivetrains, all-electric vehicles and hydrogen-powered heavy-duty trucks.

Hybrids: integrating EV components

Hybrid trucks can be a viable approach for OEMs, but this depends on careful integration of e-drive components with the conventional powertrain, as well as modifications to the powertrain.

OEMs must weigh the option of developing a dedicated or modular hybrid transmission themselves. Cost is a big factor; however, for some, this will be seen as part of their core competency, especially given the eventual full electrification of commercial trucks.

IAV has developed a concept for a hybrid module for a twelve-speed, dual-clutch transmission enabling both ICE and electrical operation.

Explains Rico Resch, project manager, transmission and hybrid driveline, IAV, “So far, P2 hybrid modules for commercial vehicles are only known for automated manual transmissions and planetary automatic transmissions. Due to the additional clutch for powershifting and launching in a dual-clutch transmission and the C0 disconnection clutch, three clutches and the electric motor need to be placed at the transmission input side.”

This is a problem Robert Bosch is working on, as well. Bosch and the University of Michigan are demonstrating a power-split, multi-mode hybrid transmission to integrate a downsized internal combustion engine with two electric motor generators. The system uses a dual-planetary gear system with multiple clutches.

The demonstration vehicle is a Class 4 walk-in delivery van with a 3.0l V6 diesel engine and Allison five-speed automatic transmission integrated with the power-split transmission.

The all-electric option

To fully exploit the addition of electric motors and batteries, some of these designs also allow for all-electric driving. For example, Bosch’s demonstration of its CV hybrid power-split transmission comes with two battery packs that let the truck travel up to 60 miles.

Given the complexities of integrating the electric components into conventional powertrains, however, combined with an all-electric future, for some it makes sense to focus on developing dedicated electric drives.

Punch Powertrain is showcasing its electric drive for delivery vans weighing up to 4,200 kg. These vehicles typically drive at lower speeds, but they need to be able to take off from a standstill, loaded, on a 30 percent uphill grade. And, because they stop so often to make deliveries, the transmission’s parking mechanism bears an intense load.

Punch used a single-speed transmission with a ratio of 1:16 and a mechatronic park mechanism. The transmission consists of two-staged pinion gearsets driving a final crown-wheel with integrated differential. The electric drive system can run at a peak of 90kW; it can bring the vehicle up to 100 km an hour.

In agricultural applications, simply replacing the conventional powertrain with an electric drivetrain while maintaining the original vehicle structure is the most common approach, according to Stephan Hammes, skill team leader of powertrain integration, AVL Tractor Engineering Germany. “However,” he adds, “all configurations that integrate an all-electric drive into an existing vehicle structure have the disadvantage that the wheel loads and the components are not ideally matched with each other.”

AVL takes a dual approach for small-size and small-volume utility vehicles: A hybrid concept downsizes the diesel and adds power via an electric motor that can be powered by a small battery. Its drivetrain architecture also allows for all-electric driving over short distances.

In addition, the company developed a restructured electric tractor based on a new modular system that can accommodate add-ons such as farm implements, power packs and even an autonomous driving unit.

Hydrogen fuel cells

It has to be noted that electric powertrains are not the only way to accomplish emission-free commercial vehicles. Toyota has continued to advance hydrogen fuel cells.

Noting that KPMG’s Global Automotive Executive Survey 2018 rated fuel-cell EVs as the top priority for that year, Luke Rippelmeyer, senior engineer, product development office, Toyota Motor NA, says, “Toyota sees hydrogen fuel cells as playing an important role in the future of transportation.”

In 2017, Toyota began work on moving components of its hydrogen fuel cell Mirai into a Class 8 truck for use in the Los Angeles–Long Beach port complex. The truck, dubbed Project Portal, combines two Mirai fuel stacks and an electric motor producing 670 hp and 1375 pound-feet of torque. Toyota says its gross vehicle weight rating is 36,288 kgs, and it can travel more than 322 km.

Project Portal went into use at the port in October of 2017. A beta version with a 12kWh battery, unveiled in 2018, increased the estimated range to more than 483 km per fill. Toyota’s fuel cell technology is optimized for mid- to long-range applications, Rippelmeyer says.

Cost vs. benefits

The benefits to the environment of hybrid or all-electric vehicles are clear and, where regulations demand the reduction of emissions or preclude diesel engines, full or partial electric driving will be essential.

On the other hand, for the electrification of commercial vehicles to really take off, the total costs for fleet owners must be on par with those of conventional vehicles. McKinsey calculates that medium-duty fleet vehicles that travel approximately 322 km per day are most likely to break even. In the heavy-duty segment, it says, urban city buses have the greatest potential for achieving TCO parity with diesel buses.

Punch Powertrain’s work with a German postal service fleet shows that this is possible.

“For the commercial vehicle segment, the main reason to go for EVs is to have fleet owners achieving an improved total cost of operation,” says Joris Bronckaers, product architect, Punch Powertrain.

This is more achievable for urban and regional delivery services, he thinks, because of the intense utilization of these vans combined with relatively low mileage. Add the lower maintenance costs of EVs and low charging costs, and fleet owners can achieve parity with ICE vans.

New tools for new powertrains

Engineers address the complexity of designing for hybrid or all-electric powertrains and transmissions by innovations in the design process itself.

Bosch and the University of Michigan developed and tested a new automated modeling process which greatly simplified the search into such a large design space. The process allowed them to evaluate more than 18 million design candidates.

Martin Ackerl, lead engineer system development on-road, AVL Commercial Driveline & Tractor Engineering, points out that a high level of integration of the e-drive components in heavy-duty vehicles may not be the optimal solution for all truck applications. AVL has a methodology to deliver flexible configurations of the components to suit different scenarios, for example, long-haul trucking versus distribution.

Infrastructure considerations

While EV adoption for private cars is hindered by range anxiety and dearth of available public charging stations, it’s expected that fleet vehicles will charge when they’re off-duty at the owner’s hub. There will be capital expenses in adding charging facilities to their facilities.

To prove the viability of Toyota’s fuel-cell trucks, the OEM also must demonstrate the ability to refuel trucks at high throughput. There’s already a temporary refueling station as part of Project Portal; Toyota has announced a permanent tri-generation station to produce hydrogen, electricity and heat.

At the CTI SYMPOSIUM USA experts will discuss the following important areas in the dedicated session on “Commercial Vehicles: Electrification and Components”:

  • Compact e-drive solutions for heavy duty vehicles (AVL Commercial Driveline & Tractor Engineering GmbH)
  • New developments for electrified powertrains for heavy duty commercial vehicles (IAV GmbH)
  • Marketable electric drivetrain concepts for small tractors (AVL Tractor Engineering Germany GmbH)
  • Electric drive development for a parcel delivery van (Punch Powertrain N.V.)
  • The role of fuel cells in the technology landscape (Toyota Motor North America)
  • Powersplit hybrid transmission for commercial vehicles (Robert Bosch LLC)
Filed under: Front-Page, Highlights, News