As part of the cover story on the future of vehicle propulsion in the July/August 2019 edition of Automotive Engineering magazine, this article is one of four that examines the near-term future of vehicle propulsion from the perspective of OEM powertrain-engineering senior executives.
Name a future propulsion solution for vehicles, and Hyundai’s on it. From advanced gas and diesel ICE, to all manner of hybrid, EV, and hydrogen fuel cell, Korea’s mobility king has it in development or in production. Competitors respectfully acknowledge their awe of the company’s rapid progress on all engine fronts in recent years.
So does John Juriga. Hyundai North America’s Director of Powertrain (below, right) has been with the Ann Arbor-based company for 16 years. “We’re very fortunate to be working on everything,” he says. “It drives us crazy sometimes, but it’s also incredibly fun because we’re developing all these different technologies concurrently.”
There are still “knobs to turn” –the key technologies that can improve the thermodynamic, volumetric, and mechanical efficiency of combustion engines, he says. “The challenge for us is how to integrate all these systems to do that. Emission requirements are getting really, really tough—standard NOx, and now N2O and particulates. They’re huge in driving the engine and propulsion system architecture. And EPA now is looking at off-cycle emissions. The complexity of what we have to accomplish is multiplied, but it’s an exciting time.”
That U.S. regulatory environment may seem to be in a ‘holding pattern’ but Hyundai remains unwavering in its powertrain plans: keeping an eye on both Washington’s regulatory tenor and also on California, with its ZEV [zero-emission vehicle] requirements, along with the Section 177 states aligned with Sacramento’s mobile-emissions policies. “Even if the federal government relaxes its regulations, our technology roadmap won’t change,” Juriga asserted.
The gasoline ICE “will remain the mainstay for decades to come—but it’s going to have high levels of electrification attached,” said Juriga. “There is nothing that currently compares to the power density of gasoline as a fuel source. And the combination of its prevalency, low cost, and efficiency means it’s not going to go away quickly. So, we focus on how to make it more efficient. That’s why electrification and combustion development are two key areas we’re working on.”
While it operates under the umbrella of Hyundai Powertrain in Korea, Juriga’s team engages in collaborative R&D projects with the U.S. DoE, networking with top universities and suppliers, in addition to spearheading North American market emissions validation and certification.
“In advanced combustion engines there are two main areas that we’re involved in,” notes Phil Zoldak, Hyundai Powertrain’s manager of engine development and testing (above, left). “One is furthering traditional boosted SI engines. The other is lean-burn engines, and within that space are two branches: Spark-ignited, which looks at dilution with EGR and advanced ignition systems, and lean-burn compression ignition. Both are gasoline fueled.
“We’re focusing more on the lean-burn development side, in what we call Technology Enablers—advanced ignition systems, advanced boosting and controls,” he said. “We use CFD extensively to co-optimize and select the right hardware.”
A DoE-sponsored program that ran from 2011 to 2018, dubbed GDCI, focused on a gasoline-fueled compression ignition engine with Hyundai working in support of partners Delphi and the Wisconsin Engine Research Consultants. It yielded significant learnings, Juriga said, but had two pitfalls. “The hardware we had to use—a turbocharger and supercharger—drove system complexity and cost. It also had no spark mode; it relied exclusively on compression ignition which compromised things like cold start. It was perhaps too aggressive.”
Co-optimizing engines and fuels
GDCI was followed by the Co-Optima Initiative, launched in January 2019 and running to 2021. Co-Optima is short for “Co-optimize Fuel and Multi-Mode Gasoline Compression Ignition Engine for Meeting Future Emission Standards.” Funded by the DoE’s Vehicle Technology Office, the program aims to create engines and fuels that are more effectively optimized together. Nine U.S. National Labs are collaborating on the project. Hyundai North America is collaborating with Michigan Technological University (simulation) and Phillips 66 (fuel development). A Hyundai 2.2-L diesel is serving as a mule test rig; “we may end up with a gas engine in the end, with a unique head geometry,” Juriga noted.
“This program is our effort to put everything into a package that is production-intent and uses more off-the-shelf-type hardware,” explained Zoldak. “The engine has the ability to start out in an SI mode, operating in a stoichiometric or lean-combustion mode, and transition into a more low-temperature combustion mode using internal residuals [EGR]. Then make another transition into a compression-ignition mode using external EGR. So, there’s three transitional modes we’re looking at as you increase load.
“The complexity of mode switching comes into play, and as you can imagine fuel octane starts to bear on this,” Juriga noted. Phillips 66 is providing a range of fuels with different octanes and reactivity. The fuels are then being modeled; “we’re using a real-fuel modeling technique that MTU [Michigan Tech] has developed,” said Zoldak.
The program aims to achieve steady-state performance first, combining simulation and hardware selection, before trying to tackle the transients that have challenged the drivability of virtually every lean-burn engine development effort.
“We’re building an engine that can capture all the modes, at specific points, on the dyno,” Zoldak explained. “The main scope of the work wasn’t to do transient testing. It wasn’t a requirement of the project, but we’ll be doing some testing in transients. We’ll handle them using a mixed-mode controller—we have different combustion modes that are calibration-optimized for that region and use algorithms to transition from one mode to another.”
Mode changeovers will be dependent on the development team’s grasp of system dynamics—the operating-speed deltas among production-intent, rather than R&D-spec hardware including injectors, EGR valves, turbo boost levels, etc.—and how they can be adjusted to operate rapidly, on command. “We’ll look at how lean can we go, and what fuel and air systems do we need to support it.” Juriga noted. New ignition-system technologies are being investigated as a sideline of the project.
“As we go through development we’ll be refining the characteristics of the compression-ignition gasoline engine with the goal of reducing emissions in cylinder,” he explained. “The merging of gas and diesel technologies is something we’ve been looking at for years.”Continue reading »