1/13/2004 | 8 MINUTE READ

The Powertrain Scene Circa Today (With A Glimpse At the Not-Too-Distant Tomorrow )

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In which Peter Brown of Ricardo—an engineering consultancy that's worked on projects from the Hummer H2 to the HEMI to powertrains that they've taken a vow of silence regarding-talks about what's going on under the hoods.


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Power Sells
In the world of powertrain engineering, which Peter Brown, vice president, Powertrain Projects & Design, Ricardo Inc. (Van Buren Twsp., MI), knows more than a little about, there is something of a slight disconnection between what is desired by the market and what is a requirement for vehicle manufacturing. That is, Brown observes, “There is a focus on emissions and fuel economy”—for the vehicle manufacturers—“but there’s a strong recognition that you can’t sell either of those things to the buying public.” So, while vehicle manufacturers and Tier One suppliers work with Ricardo—which has some 1,400 employees worldwide, and specializes in engines, transmissions and drivelines—on fuel economy and emissions, they also go to the firm for assistance with what are arguably seriously powerful engines: like the Chrysler Group’s 5.7-liter hemi Magnum V8, which Ricardo engineers, designers, and CAE engineers worked on with personnel from Chrysler. “We’re seeing more new engine programs focused on even higher levels of performance,” Brown says. He notes, for example, that General Motors’ cylinder deactivation program is a means by which larger engines can remain within vehicles while still providing comparative fuel efficiency.

The Diesel Dilemma
Although there is a lot of talk—speeches, conferences, presentations, water-cooler chatter—about diesel engines for passenger car and light truck applications—after all, everyone knows that the Europeans are buying diesels like mad: during a conference in October, 2003, Alastair Bedwell, research manager, J.D. Power-LMC, described it as a “diesel explosion in Europe,” and noted that the penetration in the western European market for diesels in 2003 is an estimated 44%, and he claimed that the compression ignition engine is now “the default choice for some in Europe”—Peter Brown sees the U.S. vehicle manufacturers being somewhat cautious. Although there is, what he describes as “significant growth and interest in the technology” by vehicle manufacturers in the U.S., he also goes on to note: “Everybody is trying to be positioned to take advantage of the market if the market takes off. There’s concern about not spending any more than you have to be to be in that position.” There is what may be considered bet-hedging because, he says, “No one knows if the diesel is going to take off significantly in the U.S.” Where is Ricardo on this question? “We think it will.”

The Diesel Dilemma, 2
One of the big challenges to moving diesels into the mainstream American market is related to emissions. “NOx is clearly the issue, and the catalytic systems for treating NOx are challenging on diesel engines,” Brown explains. Oh, yes, and he adds, “And quite expensive, too.” Those precious metals for catalysts don’t come cheaply. The Ricardo approach to handling diesel emissions is, consequently, to reduce engine-out emissions as much as possible, then using the catalytic systems to treat what’s left.

And there’s another issue related to diesels and costs, which is that compared to a spark-ignition engine (i.e., a gasoline-powered vehicle), the diesel is more expensive. So there is the likelihood that if diesels go forward in any significant way in the U.S. market, they’ll be moving along in high-end vehicles or those that provide some profit margins to work with. “If you had to install diesels on small, economical vehicles,” Brown posits, “it would probably be a loss situation.” The margins are too thin there.

Speaking of the cost situation as regards diesels, Brown notes that vehicle manufacturers are paying a whole lot of attention to improving gasoline engines because they know that they can make more money that way.

Manufacturing Matters
“The manufacturing capabilities that we have today are so much better than they used to be, and that allows us to design engines with much closer tolerances. That makes those engines have lower friction levels, be much quieter, perform better overall, and be much more reliable.”

Sure, while the control capabilities—Brown says that electronic control systems “have allowed all kinds of developments that we couldn’t have thought of 10 years ago”—have made a big difference in what engines can do, it is the fundamental manufacturing of these engines that make a tremendous difference.B

What Would He Do?
Let’s assume that Peter Brown was able to put together his ideal engine. What would it be like? This: “An all-aluminum engine with no iron cylinder liners. It would have four valves per cylinder. It would have dual overhead cams. Two cam phasers. It might have some other unique valve-train configuration like the BMW Valvetronic. Direct injected. Probably turbocharged.”

Ideal, yes. But Brown admits: “Not every vehicle needs that kind of engine.”

“The day will come—maybe in the not-too-distant future—when you don’t refer to a ‘gasoline engine’ or a ‘diesel engine’ or a ‘spark ignition’ or a ‘compression ignition’ engine,” Brown says. The engine in question, he explains, will be something of a hybrid. And it will be called an “HCCI engine.” That’s as in “Homogeneous Charge Compression Ignition.”

Apparently, the HCCI engine can be as efficient as a direct-injection diesel engine. Yet it produces little in the way of NOx and particulates (hydrocarbons and carbon monoxide are a different story). One of the reasons why there’s a reduction in particulates is because the charge is well mixed, which is akin to what happens in a spark-ignition engine. Compared to the systems in today’s direct-injected diesels, the injection systems will probably operate at lower pressures, which will keep the costs down. As for the fuel, it could be something of a combination of gasoline and diesel fuel, something that the powertrain insiders sometimes refer to as “dieselene.”

One of the tricky parts of making an HCCI engine work is having precise control over temperature, pressure and the fuel-air mix for appropriate combustion. The one thing that is making the HCCI engine even possible are the burgeoning improvements in control technology.

Time frame? “Easily within 10 years,” Brown answers. “He adds, “The heavy-duty segment of the market will probably see it in five years or less.”

The Future Is. . .The Future
Certainly, when you’re talking with a powertrain engineer and you’re talking about advancements in powertrain technology and you’re on the subject of the future, the question that must emerge is “What about fuel cell-powered vehicles?” And Brown answers, “Some day. A long way out in the future.” Yet he adds, “I do think there’s some interesting work going on these days in hydrogen-fueled internal combustion engines.” As an admitted Wankel fan, he notes, “Mazda is doing some interesting work on the hydrogen-fueled rotary engine.”C But he goes on to note that there is the prevailing problem of the lack of availability of hydrogen fuel in the marketplace

Meanwhile, Back In the Present
“There’s never been a better time to be in the powertrain engineering business because the sky’s literally the limit in terms of what we can do today—things that people only dreamed of before.”

A. GM Powertrain is calling the cylinder-deactivation system “Displacement on Demand” (DOD). It will be making its appearance on a number of the vehicle manufacturer’s engines, including the new 3900 V6 in 2005; it will debut on the Gen IV Vortec 5300 V8 on the ‘05 Chevrolet TrailBlazer EXT, GMC Envoy XL and Envoy XUV. The DOD system employs an engine controller that determines when cylinders can be deactivated such that the driver doesn’t notice the change. Determination is made by measuring factors including oil temperature, rpm, coolant temperature, and throttle condition. For example, when cruising along on a highway, there is a comparatively light engine load, so it may be possible to deactivate cylinders: the V8 operates as a V4 as alternate cylinders on each bank are deactivated. To effect deactivation, there are special two-stage hydraulic valve lifters that have both inner and outer bodies. In normal operation, each valve lifter works as a single unit. When deactivation is to take place, the outer body moves along with the camshaft actuation, but the inner body is stationary so that the pushrod is held in place. Because the pushrod doesn’t actuate the valve, no combustion takes place. Also, the electronic throttle control increases intake manifold pressure when the cylinders are deactivated so that the torque load in the V4 mode is maintained at the V8 level.

B. A recent example of the kind of control power that is becoming available is the MPC5554 32-bit embedded controller from the Semiconductor Products Sector of Motorola. The PowerPC-based unit has 2 MB of embedded flash memory that can be read and written simultaneously. According to Ray Cornyn, the Motorola 32-Bit Embedded Controller Division’s Operations Manager, the flash capability facilitates upgrading and updating software. Another thing that was taken into account when the microcontroller was being developed was future application. Cornyn says they’ve built in “headroom performance of things like electronic valve control.” Speaking of the chip he claims, “This is highly optimized for embedded control. It’s performance in terms of the CPU is what Macs had a couple of years ago. But this is located under the hood of your car and is expected to last for 20 years.” Don’t try that with your iBook.

C. At the 2003 Tokyo Motor Show, Mazda showed a prototype vehicle, the RX-8 Hydrogen RE, which features direct injection of hydrogen into the intake chambers through two electronically controlled injectors per rotor. Apparently, one advantage of using hydrogen in the RENESIS rotary engine rather than in a conventional piston engine relates to the fact that in a rotary engine’s combustion chamber, the induction, compression, combustion, and exhaust take place in different areas so, unlike the case with a piston engine, when the hydrogen is injected, it doesn’t pre-ignite, as it can in a piston engine where the spark plug and combustion chamber walls tend to be sufficiently hot to cause the flammable gas to combust too soon. Also, the combustion chamber in the rotary engine is larger, which facilitates a better burn of the fuel. Because Mazda engineers recognize the limited availability of hydrogen fuel, the RX-8 Hydrogen RE is a dual-fuel vehicle: it can also run on gasoline.


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