Delphi injects life into diesel
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The DFI 21 injector valve can provide up to nine injection events per cycle. Delphi is currently manufacturing beta-level samples of the new injector in batches of several hundred. (Delphi)

Delphi injects life into diesel

Delphi Technologies is predicting a period of unprecedented change for the truck and off-highway powertrain markets. However, chief technology officer Mary Gustanski reports that the company is more than ready to meet the challenges that lie ahead.

“We are at a pivotal point in technology,” she said. “Change is going to happen and it’s going to be dramatic.”

What was once considered futuristic driveline technology is now just a few years away, with electrification and autonomy among a host of new challenges for OEMs and their Tier 1 providers.

However, whether driven by customer demand or by regulatory forces, there will still be a need for an efficient, cost-effective means of propulsion to power equipment, whether that involves electricity, gas, diesel or any other fuel.

“Autonomy doesn’t happen unless the future of propulsion happens,” said Gustanski. “Electrification is on the rise, but the internal combustion engine is not dead.”

Indeed, while Delphi agrees with industry predictions that 50% of trucks and machines will incorporate some form of electric driveline by 2030, it claims that the majority of those powertrains will be hybrid drives, utilizing a combustion engine to provide electrical power.

The task is not simply how do we move to electrification, but how do we continue to make the internal-combustion engine better?

To meet these changing manufacturer requirements, Delphi has been working on a range of technologies. The company is investing heavily, pumping 8% of its 2017 revenues of $4.8 billion into technology development. Perhaps tellingly, 30% of the firm’s engineers are focused on software solutions, rather than hardware, while Delphi is increasingly being involved earlier in the planning stage by OEMs keen to explore electrification.

DFI 21 fuel injector

Among a range of new products and technologies, Delphi has begun pilot production of a micro-valve fuel injector, for medium- and heavy-duty diesel engines. The high-precision DFI 21 injector uses a valve that is just 1.0-mm in diameter, half that of the firm’s popular F2 Euro VI injectors.

Despite these compact dimensions, the DFI 21 injector valve can provide up to nine injection events per cycle, rather than the two or three of the current Euro VI injector. The injector uses a 3,000-bar (43.5-ksi) common-rail injection system, though it will also provide improved operating efficiency at 2,400 bar (34.8 ksi).

This allows engine manufacturers to profile the entire combustion cycle, controlling temperatures for improved performance and reduced emissions. For instance, it could be set to provide up to five pilot injection events, the main injection duration and then three post injections, all of which could be at variable injection pressures and all within 20 degrees of crank rotation. 

Digital rate shaping of multiple injections results in constant NOx output, up to a 3-dB reduction in combustion noise, 60% less smoke and up to a 1.5% fuel efficiency improvement. The DFI 21 is suitable for use with both EGR (exhaust gas recirculation) and non-EGR engines.

“Reducing engine-out emissions gives engine designers much greater flexibility in their aftertreatment strategy, with some significant potential cost savings for the vehicle manufacturer and the vehicle operator,” said James Kewley, product engineering director. “For example, DFI 21 could allow simplification of exhaust aftertreatment and a reduction in SCR [selective catalytic reduction] fluid consumption, which can be of significant value to long-distance truck fleets.”

While Delphi has employed closed-loop control of combustion for some time, the new F3 system adds closed-loop compensation for any variation between individual injectors. This is said to ensure that the injection events will remain accurate throughout the engine’s life.

The F3 common-rail system is the company’s first to cover both heavy- and medium-duty engines, from 0.7-L per cylinder up to 3.0-L per cylinder. It is compatible with existing packaging dimensions to make it easier for engine OEMs to install in existing architecture. 

Manufacturing a challenge

Producing a 1.0-mm diameter injector valve is no simple task. Delphi produces almost 3 million fuel injectors a year at its Stonehouse plant in the UK, covering everything from Euro III to Euro VI engines.

In the firm’s F2 NCV Euro VI valve assembly, the 2.0-mm valve has a 1-micron clearance, with 4 microns of valve lift. For the 1.0-mm valve, the stem clearance is reduced to just 0.5 micron, with a valve lift of 1 micron. Indeed, even handling the valve components could affect the finish, so vacuum grippers are used to place the pins and valves.

Delphi is using cubic boron nitride (CBN) grinding abrasives to match-hone the pin and bore diameters. Orifices are laser drilled, as a conventional drill bit stem would not be strong enough.

Every DFI 21 injector will be tested to 3,600 bar (52.2 ksi) before calibration. Delphi is currently manufacturing beta-level samples of the injector in batches of several hundred, using production-representative processes that are readily scalable. 

“One of the proven strengths of our team is that we have very robust Start of Production (SOP) processes, leading to efficient product introductions with consistently high quality from delivery one,” said Kewley. “DFI 21 pushes high-precision, high-volume manufacturing technology to the limit. Our goal is to make this remarkable achievement seem simple.”

The company expects the injector to be in production by late 2020 with the first program.

“Future-proof” power electronics and controls

While continuing to work in the combustion engine arena, Delphi, like so many manufacturers and suppliers, has had an eye on the electric-drive market for some years. The company doesn’t make electric motors or batteries, but it has specialized in the fields of power electronics and controls—what Gustanski refers to as the “secret sauce.”

“In an engine controller today [for an internal combustion engine] we put about a million lines of software to make that vehicle move. In the inverter that [drives] electric functionality there’s a million lines of software. It’s just as complex,” she said. “What we continue to do with controllers is add more and more computing power so that we’re ‘future proofing’ them, because everything is software-enabled now. We’ve added in enough computing power so we can continue to add features and functionality in this controller for the future.”

Having a solid understanding of electronic controls in an automotive setting has been a major bonus for Delphi, and the company believes it is this strength and experience that will push new technologies forward.

“This is a logical step for Delphi Technologies, as it brings together three closely aligned areas where we already have considerable expertise,” said Martin Knopf, managing director, electronics & electrification EMEA. 

“Our electrification technologies for passenger cars are already winning substantial new business and are directly scalable; we have proven capability in state-of-the-art CV engine management and powertrain control technologies; and finally, our long-term relationships with leading CV manufacturers around the world give us a proven understanding of the duty cycles and other specialist requirements of each CV sector.”

An example of Delphi’s expertise in the area is the latest Viper high-voltage power switch. With double-sided cooling capability, the Viper high-voltage power switch is said to provide superior thermal management, allowing smaller packaging requirements.

“Range and charging time are even more critical to CV operators than they are to passenger cars,” said Delphi Technologies commercial vehicle sales director Richard Green.

“Electrification has traditionally not been particularly light or compact, both of which are critical to operators who need to carry paying passengers or cargo, not additional technology. Our Viper differentiated power switch is designed with no wire bonds which greatly improves reliability and thermal management, which is crucial in electric powertrains.

“It also allows for flexible mechanical packaging options and scalability for our inverter. The net result is that our inverter is 30-40% smaller and lighter than the competition.”

Delphi’s engineers are already working with OEM customers on electrification up to 800V. 

“Higher voltages allow smaller, lighter electrification systems, increasing vehicle capacity and allowing faster charging to help keep them working,” Green said. 

“Further along our technology roadmap we are confident that power electronics based on silicon carbide semiconductors will allow another step-change in efficiency, and Delphi Technologies expects to be one of the first to market with a highly-robust system.”

Delphi Technologies is in good financial health and is working hard to meet the challenges that are coming. As with the OEM manufacturers that it supplies, the company is having to invest in a wide range of technologies, to suit a range of customer requirements.

“We have a full portfolio of solutions. We’re pretty agnostic—petrol, diesel, hybrid, natural gas—we’re ready for that and we’re staying close to the market,” said Gustanski. “To be a propulsion supplier today, nimble and flexible is the way. But you can’t turn a 30% move to battery-electric vehicles on like a light switch.” Continue reading »
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