Dual intentions - Delphi Technologies talks powertrains

Jon Lawson

While the name Delphi will be familiar, Delphi Technologies is a new, separate global venture with a different focus. To mark the second anniversary of its creation, the company’s recently appointed VP of Engineering, Harry L. Husted, ponders the challenges ahead for powertrain innovation and explains what the company is doing in response.

History of Delphi Technologies

I’d like to start by mentioning how Delphi Technologies came about because that’s a useful illustration of some of the fundamental changes in the business of developing automotive technologies.

After taking a hard look at the trends in mobility technology, we realised that the needs of a company specialising in autonomous driving and connected safety systems were significantly different from those required for the development of next-generation, low emission powertrains. The global centres of expertise for these businesses were different and they also attracted different types of investors. It was an easy decision to split Delphi Automotive into two: Aptiv, focusing on connectivity and autonomy, and powertrain specialist Delphi Technologies, with a new global headquarters in the UK.

We emerged as an independent company in 2017. This was an interesting time for powertrain technologies: diesel was entering a rapid decline, electrification was being driven hard by most of the major governments and a major step in carbon dioxide targets was approaching.

But change is also an opportunity and because we are a new company, we have been able to form our business around these trends. Our gasoline direct injection team has introduced a novel 500 bar direct injection system, while our electrification business has been able to step straight into next-generation technologies such as 800 volt inverters that help solve the range and charging challenges of electric vehicles.

From diesel engines to high-pressure GDI

In the heavy-duty long-haul truck sector, there is currently no realistic alternative to diesel engines. The weight and cost of batteries aren’t economical for an electric powertrain (or highly electrified powertrain) solution.

In the high-load, steady-state conditions of long haul, diesel engines are very efficient, with excellent power density, low carbon dioxide emissions, and low pollutants with aftertreatment.

New generation precision fuel injector launch

So, for heavy-duty commercial vehicles, we are about to launch a new generation of ultra-high precision fuel injector that uses an innovative 1mm valve to improve the injector’s opening/closing speed and thus its ability to deliver fuel flexibly and shape the combustion event.

When combined with fuel delivery pressures up to 3,000 bar and up to nine injection events per cycle, this allows much cleaner combustion, which means lower engine-out emissions and excellent fuel economy. Faster control means peak temperatures, and hence NOx, can be reduced, multiple pilot injection events can be employed to enhance refinement by slowing the rate of pressure rise, while multiple post-injection events can be specified to reduce soot formation.

Manufacturing innovation key to meeting durability targets

The durability targets for medium and heavy-duty trucks are exceptionally demanding, so manufacturing innovation is a key part of product development. We are working with sub-micron clearances, with tolerances at least as demanding as those found in the latest jet turbines.

Grinding processes using cubic boron nitride (CBN) have been developed beyond anything that had previously been achieved, complemented by new surface finishing techniques to eliminate burrs at the sub-micron scale.

For passenger vehicles, gasoline engines continue to take market share from diesels. Traditional gasoline port fuel injection systems have been replaced by Gasoline Direct Injection (GDi), allowing more efficient combustion while mating well with turbochargers to enable the additional efficiency gains of engine downsizing.

As with diesel injection, the key is very fast, high-precision control of fuel injection events at high pressures. We were first to market with a GDi system operating at 350 bar fuel pressure, and at the 2019 Vienna Motor Symposium, we revealed a new 500+ bar GDi system that can reduce particulate emissions (both mass and number) by up to 50% compared with today’s state-of-the-art 350 bar system.

Reducing engine-out emissions cuts tailpipe emissions in the crucial period before catalyst light-off and allows post Euro 6d and China 6 emissions standards to be achieved with simpler aftertreatment. Higher fuel pressure can also make the combustion process more efficient, which may offer an improvement in fuel economy of up to 1%.

Manufacturing innovation crucial for GDI development

As with the new system for medium and heavy-duty diesel engines, manufacturing innovation has been an important part of the development process for GDi. Switching to a forged high-pressure fuel rail, for example, has allowed a 25% component weight saving. More advanced materials have allowed simplified fabrication with reduced welds and fittings while also enhancing durability.

Materials innovation has also been central to our ability to solve one of the biggest challenges with higher pressure GDi. The industry has struggled to figure out a way to provide higher fuel pressures without putting additional stress on other engine components that would then require costly re-engineering and upgrading.

Our solution is an innovation to the GDi pump plunger sealing that allows it to come up to pressure very quickly (around 23% faster than today’s typical GDi systems) and to maintain pressure at low RPM – both critical for fuel economy and emissions – while actually reducing stress on the camshaft drive surfaces by up to 30%.

Is the future of engines electric powertrains or internal combustion engines?

We believe that the internal combustion engine will be around for many years to come. I have already mentioned its strengths for long-haul, heavy-duty trucks. In the passenger car segment, vehicle electrification is seeing strong growth, and we are embracing this change.

However, even if the market for pure electric vehicles grows at an unparalleled rate to account for 30% of the global fleet by 2030 as many predict, that still leaves 70% of new passenger cars being delivered with an internal combustion engine 10 years from now.

Many vehicle manufacturers are significantly reducing their investments in new internal combustion engine development. Whereas only a few years ago they were committing to new generations of increasingly complex engines. Money today is being spent on the best engine management/fuel injection systems to upgrade existing engines and on increasingly clever integration of electrification because, when tightly integrated, internal combustion engines and electrification together can create a benefit that is more than the sum of its parts. Propulsion systems that combine electric and combustion technologies in a highly synergistic way will, therefore, continue to emerge.

Adding connectivity for a positive environmental impact

We then add in the benefits of a connected world through what we are calling Intelligent Driving. Delphi Technologies is working with TomTom to develop the use of real-time mapping data to give the vehicle prior knowledge of conditions such as route infrastructure, hills, traffic congestion and traffic signal patterns.

By allowing the propulsion system to make better decisions about things such as when to use electric power or gasoline power, and by using look-ahead information to control the vehicle speed, Intelligent Driving technology can reduce the carbon dioxide emissions of a mild hybrid by up to 10% without increasing travel time under real-world driving conditions. When applied to higher levels of electrification, Intelligent Driving technology has the potential to improve efficiency even further and to increase electric driving range.

Technology trends in battery and hybrid

IHS estimates that by 2025, around 45% of new passenger cars will be electrified. But these electrified fleet will not be homogeneous, comprising a mix of mild and strong hybrids, plug-in hybrids, and fully battery electric vehicles.

The technology requirement for electrification is therefore diverse, so one of the most important characteristics from the manufacturers’ perspective must be flexibility: the least possible change to accommodate the necessary number of specifications. In terms of performance goals, batteries are expensive and heavy, so efficient management of energy is important to deliver the maximum driving range from the battery pack, alongside the rate at which the battery can be recharged.

Higher voltages in electric powertrains

The trend to higher voltages is an important part of the solution. At the 2019 IAA (Frankfurt Auto Show), we highlighted a large business win for a silicon carbide inverter at 800 volts, significantly extending electric vehicle range and enabling an up to 50% reduction in charging times compared with today’s state-of-the-art 400 volt systems. At the heart of this inverter is our compact Viper power switch.

This smart technology eliminates the need for wire bonds that can create quality and reliability issues and introduces double-sided cooling, allowing the inverter to be 30% smaller and 40% lighter than an equivalent unit using conventional technology. The 800 volt configuration takes a further step by employing silicon carbide MOSFETs (metal oxide semiconductor field effect transistors), a wide-band-gap semiconductor technology that allows ultra-fast switching and higher operating temperatures. Inverters are one of the highest-value electrification components and their efficiency has an industry-changing impact on many aspects of vehicle performance.

800 volts is not just about faster charging: it’s also about providing a much broader range of capabilities from which the vehicle manufacturers can select. A higher voltage introduces options that include more range or a smaller battery; ultra-fast charging or lighter, less-costly cables and connections, and greater harvesting of vehicle kinetic energy when braking, which further extends vehicle range.

Harry L. Husted concludes

It’s a fascinating time to be in this industry, not just because of the dramatic rate of change, but also because it drives what I would call real engineering innovation. ‘Real’ because although we are doing amazing new things, we also have to think hard about flexibility and eliminating complexity. In many respects, these are the biggest challenges as it is success in these areas that will determine the competitiveness of new-generation vehicles and how fast the market will accept them.