Japanese Truck Makers Focus on Cutting Emissions

TOKYO – Japanese truck makers, their sights set on future emissions standards in the U.S. and Europe, continue to make advances in combustion technology and engine downsizing.

Isuzu, the nation’s top truck brand, is emphasizing both downsizing and improving thermal efficiency.

“The bottom line for Isuzu is improving the diesel engine,” says Satoru Kaga, senior executive officer in charge of powertrain and drivetrain planning.

Kaga, who is closely monitoring the U.S. Department of Energy’s SuperTruck Program, believes a 2%-3% improvement can be achieved in Isuzu’s heavy-duty engine lineup through the introduction of more precise electronic controls, including “total” drivetrain controls that would integrate powertrain, braking and shift-speed functions.

He expects to complete the development of a total drivetrain management system in the next two years and eventually introduce the system throughout Isuzu’s lineup.

Longer-term, Kaga believes 8%-10% fuel-economy improvements can be achieved in the powertrain area.

All the while Isuzu will continue to work on reducing engine size, although Kaga says most downsizing is complete – from 9.8L to 15.7L for part of the truck maker’s heavy-duty lineup, 5.2L to 7.8L for medium-duty F series and Forward trucks, and 3.0L to 5.2L for light-duty N-Series and Elf trucks.

The truck maker currently makes six diesel engines and one gasoline unit for its lineup of pickup trucks, light-, medium- and heavy-duty trucks, and commuter buses.

Among them are the 6-cyl. 6UZ1, developed for 9.8L Giga and C/E trucks, which produce 380 hp and 1,301 lb.-ft. (1,765 Nm) of torque, and the 4-cyl. 4HK1, which makes 150 hp and 298 lb.-ft. (404 Nm). The 4HK1 is one of the options for the medium-duty N series and Elf trucks.

Isuzu is phasing out the gasoline V-6 engine installed in its Thailand-built pickup truck, the D-MAX, and likely will source a replacement engine from one-time equity partner General Motors. It currently purchases 4-cyl. gasoline engines from GM.

Transmissions are another matter, and Kaga reports most Isuzu transmissions feature five gears. He hopes to increase that number to six or seven in the future.

Kaga is cool toward hybrids, noting Isuzu is putting less emphasis on diesel-electric technology than its two main Japanese rivals, Hino and Mitsubishi Fuso. Isuzu sold 214 Elf Hybrids between January and September 2013.

“At present, there isn’t sufficient cost merit,” he says, adding, “Diesel price will be the determining factor.”

Kaga believes the truck maker can reduce oxides of nitrogen emissions 50% by 2025. Japan’s current NOx standard is 0.7 g/kWh. Starting in fiscal 2016 it will be lowered to 0.4 g/kWh. All Isuzu trucks (light-, medium- and heavy-duty) are equipped with diesel particulate filters. Upper-medium and large grades also employ NOx-reduction technology such as urea systems.

The Isuzu executive reports the truck maker will switch to alternative fuels where possible – compressed natural gas, liquid petroleum gas and dimethyl ether, although he sees DME, a potential substitute for propane in LPG, as the least promising in the near term.

Mitsubishi Fuso to Get Daimler's BlueTec

Mitsubishi Fuso is focusing on systems and components to meet Euro 6, post-Euro 6 and other future emissions standards. Topping the list, according to Koichi Itabashi, director in charge of powertrain development, are high-pressure injection and combustion technologies.

For diesel trucks, new Euro 6 standards are 0.13 g/km in the case of hydrocarbons (down from 0.46 g/km), 0.4 g/km for NOx (down from 2 g) and 0.01 g/km for particulates (down from 0.02 g/km).

Kawasaki-based Mitsubishi Fuso coordinates development activities with Daimler Group, primarily the Daimler Trucks Div. When Mitsubishi spun off the truck maker in 2003, Daimler took a 43% equity stake. In 2011, Daimler raised its holdings to 89.3%.

Mitsubishi Fuso has adopted Daimler’s BlueTec NOx-reduction system, becoming the first truck maker to employ the technology on light-duty commercial vehicles – specifically, on the Canter, which is sold outside Japan as the F series. The system employs selective catalytic reduction and NOx-absorption technologies.

A second example of working together is multisourcing of exhaust-gas-recirculation systems. Fuso relies on Daimler suppliers in Europe for EGR systems in heavy-duty trucks, Japanese suppliers for medium-duty trucks and Fiat Powertrain Technologies for light-duty trucks.

Itabashi believes engine improvements of 2%-3% can be achieved by reducing friction and improving valve timing and related components such as air compressors, power-steering pumps and vacuum pumps.

Concerning transmissions, he predicts Fuso’s Duonic mechanical-automatic gearbox will improve fuel economy 5%. The research executive notes, however, that Fuso’s first priority is improving engine performance.

The truck maker is bullish on hybrids, as well. Within the Daimler Group, Fuso has been designated the main development center for hybrid technology. The truck maker opened a global hybrid research and development center in 2008 in Kawasaki.

Itabashi explains both Fuso and Daimler regard hybrids as a key technology for improving fuel economy in the truck industry, “especially for light-duty trucks even though volumes are still small.” The key to successful hybridization, he says, is whether mileage improvements can compensate for higher system costs.

He also sees potential for hybrids in the heavy-duty truck segment. To this end Fuso exhibited a heavy-duty hybrid truck at the 2011 Tokyo auto show.

“It is difficult to forecast the hybrid share of future truck sales,” Itabashi says. “But we estimate that by 2020 it will be somewhere between 5% and 20%.” Analysts think closer to 5% is more likely.

The truck maker is not prioritizing natural gas. While acknowledging opportunities in markets such as Thailand, India and China, Itabashi insists hybrids will be Fuso’s main focus.

Hino Eyes Gains Via Conventional Technology

Hino, Toyota’s truck-making subsidiary, believes it still can make 10% improvements in fuel economy through conventional technologies such as friction reduction and exhaust heat recovery.

Shigeru Suzuki, general manager of the truck maker’s product planning and technical management divisions, says Hino is developing technology that will boost heat efficiency 10% to 15% from current levels of 40% to 46%.

The truck maker also is working to improve NOx purification efficiency through its SCR and diesel-particulate active-reduction (DPR) systems.

Hino is a leader in hybrid technology for trucks. Between January and September last year, the Toyota subsidiary sold 721 units. Unlike Toyota’s Prius hybrid system, a 2-motor, series-parallel type, Hino employs a 1-motor parallel system for its Dutro Hybrid that is built in-house.

Shigeru estimates the system including the nickel-metal-hydride battery pack results in a 6% to 7% cost penalty compared with non-hybrid versions of the Dutro.

Suzuki believes fuel prices will play a big role in whether truck makers switch to hybrids. “Japanese truck makers complain that current diesel prices of about ¥120/liter ($4.47/gallon) are painful,” he says. “If the price rises to ¥140 ($1.38) levels, I expect there will be interest in hybrids.”

The Hino executive expects hybrid sales’ share to grow but by 2020 will be short of 10%.

Hino might introduce brake-energy regeneration technology by 2025, Suzuki says. Hybrids offer the greatest potential for light-duty trucks such as the Dutro, although Hino is considering heavy-duty trucks in the future, he says.

Also in the future, Hino plans to introduce comprehensive energy-management technology incorporating the hybrid battery and inverter.

Concerning Hino’s engine and transmission lineup, the truck maker offers four engines and five transmissions (10 combinations) for heavy-duty trucks, three engines and four transmissions (six combinations) for medium-duty trucks; and one engine and four transmissions (four combinations) for light-duty trucks.

Meanwhile, UD Trucks, the former Nissan Diesel Motor and now a subsidiary of AB Volvo, is considering eliminating the 13.0L version of its Quon heavy-duty truck and concentrating on the 11.0L model. A company official offers no timeframe.