POWERING ASPIRATIONS01 September 2011
Powertrain development is very much at the forefront of manufacturers' plans, as the 2011 IAA Frankfurt Motor Show clearly demonstrated. Ian Adcock was there to get a close-up view of the action
It's one of the big events in the automotive calendar – the IAA Frankfurt Motor Show – and everyone exhibiting there is out to make an impression.
In some cases this year, a mega impression. Yet away from the glitz and glamour of ego-boosting stands – such as Ford's partially covered 5,000 sq m extravaganza that, similar to Audi's, boasted a test track that customers could drive cars around – there was plenty of new technology on display. Powertrain development was high on the agenda and is likely to remain so with manufacturers for the foreseeable future. Here, we highlight some of the leading technologies on display.
Corona ignition lights the way
Federal Mogul is claiming up to
10% fuel savings with its Advanced Corona Ignition System (ACIS), according to Kristapher Mixell, Federal-Mogul's director, advanced corona ignition system development, while allowing manufacturers to run much higher levels of exhaust gas recirculation (EGR).
Replacing the conventional spark plug is a four-pointed star that transmits a low current 25,000 volt discharge into the combustion chamber. Running at 1 MHz, the high intensity plasma stream excites the fuel-air molecules into combusting, unlike a conventional spark plug, which relies on ignition.
Although Corona technology patents date back nearly half a century, its development has been held back by the lack of advanced electronic control systems, while the conventional spark plug was performing adequately. But, says Mixell, big "game changers" with NOx and CO2 demands in the next five to six years have helped drive its development.
"The key thing about this is replacing a 1mm spark plug gap with a 30-40mm electronic pulse. So, instead of an intense local thermal event, we're using this large area of ionisation to combust the fuel," he explains, adding: "The voltage can be rapidly varied, as fast as the computer can tell it to change, and according to the individual needs of the combustion chambers."
With increased levels of EGR, combined with leaner mixtures and higher compression ratios, it becomes increasingly difficult for conventional spark plugs to ignite the mixture. "Some high EGR engines are quite chaotic, and need to run large turbulence and high energy level in the coil of 120+ millijoules to light off 25-40% EGR," states Mixell. "The problem is that, if you had to run that energy into a spark plug for 3-5 milliseconds, it wouldn't last long and, secondly, running high levels of charge motion reduces fuel efficiency."
ACIS is currently undergoing bench testing, which has seen
10% fuel savings on a 1.6-litre turbocharged direct injection engine but, says Mixell, it will be another "three to five years" before it reaches production.
An electrically powered brake system that can reduce stopping distance by up to two metres from 100Km/h – and is capable of getting 100bar pressure into the brake system within 130 milliseconds or three times faster than a normal driver – has been released by TRW.
Although its Future Brake System (FBS) is primarily aimed at electric and hybrid vehicle applications, TRW's director brake systems and application engineering, Manfred Mayer, says it would also enhance active cruise control and collision mitigation, without driver intervention in conventionally powered cars, as well as meeting all the standard brake and control functions, such as ABS and electronic stability control.
To minimise costs, TRW has scoured its parts bin, using many components from its EBC460 slip control family, while the 12v, 800 watt electric motor is derived from TRW's electric power steering system.
Instead of the driver applying brake pressure via a vacuum booster, it is done by an electric motor that moves a piston or plunger back and forth to create pressure for the brake system. "To give the driver the right feeling, with a pause, effort and deceleration feedback, there's a simulator, spring and piston device that replicates brake feel," explains Mayer, adding: "The feedback is tuneable, according to how the OEM wants the brakes to feel."
Although an 800 watt motor is installed on this model, an 'A' class car would only require 400-500 watts, he says, and that for most of the time it's operating at only 50 watts. Customer evaluation is currently underway, with the first products expected on the market within four to five years.
Twin-cylinder range extenders>/b>
Meanwhile, Lotus Engineering and KSPG AutoMotivePower, formerly known as Kolbenschmidt Pierburg, unveiled two very different twin cylinder range extenders.
While the Lotus offering is a development of its current three-cylinder Lotus Fagor Ederlan motor, KSPG's – developed in conjunction with FEV – is a radical, horizontally mounted Vee-twin, with a vertical crankshaft linked to a pair of generators via a geared drive.
The vertical crankshaft requires only a short construction height, so the module can be integrated beneath the floor of a small passenger vehicle. At Frankfurt, it was displayed under the rear floor of a Fiat 500.
Weighing little more than 60Kgs, the 799cc four-stroke, with its 80mm bore and 79.5mm stroke, develops 30kW and 66Nm, both at 4,500rpm. The engine complies with Euro6, while a pair of generators, which help to compensate the crankshaft vibrations, each produce 15kW. As in large capacity V8s, the camshaft is located within the vee.
First order inertia masses, explains Prof Dr-Ing Eduard Köhler, vp research and technology for KSPG, are compensated for by balance weights, with crankshaft vibrations eliminated by the twin generators.
"The basic design comes from both ourselves and FEV; but the vibration compensation system – that's patented by FEV and this is its first application" he reveals, adding:
"My feeling is that the automotive industry doesn't really believe in the sub compact EVs, as they are rather expensive.
On the other hand, if you have a range extender, you can minimise the battery size to an acceptable 30-50Kms range, and come down from 16Kwh to 6-8Kwh to reduce cost and weight.
"I think this package will work for the next 12 years, but what will come after 2020-25, no one knows."
Comprising two-thirds of its current three-cylinder range extender,
the latest Lotus Fagor Ederlan development requires 44% less packaging space and is 14% lighter, with a height of just 32.7cms. In its horizontal format, the engine is barely larger than an airline carry-on case. Producing 20kW and 66Nm, the 0.9 litre, two-cylinder operates at its most efficient engine speed range of between 1,500-3,500 rpm.
"We wanted to integrate the engine even more as a self-contained product, an off-the-shelf solution assembled into a single system with its control system and electric motor," comments director of Lotus Engineering, Mark James, who says that development of the original three-cylinder, 50kW range extender will be completed by the end of November and that production of the two-cylinder could start realistically, in 26 months' time. "We've always considered these range extenders as a commodity for OEMs, like many other components which don't affect brand values."
Delphi push GDI
Stratified Gasoline Direct Injection (GDI) can deliver CO2 improvements of up to 20%, says Delphi's engineering director Europe gasoline, Dr Sebastian Schilling, and even homogeneous GDI can be 15% better than a multi-point fuel injection (MPFI) system. Delphi is working on both, he reveals, to assist OEMs achieve Euro6 emission requirements.
"We're working on the particulate numbers for Euro6, but the challenge for gasoline engines is the particulate numbers, which are likely to be the same as for diesels. The other challenge is CO2; but, with GDI, OEMs can downsize – still getting plenty of cooling into the cylinder, while increasing the compression ratio – and still use a turbo.
Simultaneously, they can move the operating point to a higher BMEP, so they end up with a smaller engine with fewer cylinders and a lower parts count, reducing frictional losses and costs."
Delphi is working on both strategies with multi-hole Multec12 injectors – between five and seven, depending on the application. Schilling says Delphi has paid particular attention to injector noise and, by decoupling the armature, has significantly reduced noise radiation.
Coking, a particular problem in Asia with its varying fuel qualities, is another challenge that Delphi claims to have overcome by careful design of the injector holes, using bores and counter bores to prevent burnt fuel accumulating around the holes, which also helps to reduce particulate levels.
Running at 200 bar, Delphi's Multec 20 differs by employing an outboard opening injector. "The first of these systems was from Bosch for a Mercedes-Benz stratified charge engine, using Piezo actuators and not a solenoid, as Delphi does."
Schilling claims real cost benefits for its standard solenoid system over Piezo technology. The advantage the latter has is that it's capable of making half strokes and is faster than a solenoid. But, maintains Schilling: "You need to develop good functions to compensate for that. We can control the injector stroke when it's between fully opened and closed.
"That's very important for Euro6, because, for every gram you're injecting and not coming to the right ignition point, that can increase particulates and no one wants a particulate trap on a car.
"The big advantage with stratified GDI is that you can inject the fuel in the same position every time to achieve a really lean mixture and fuel atomisation. I think stratified will dominate in the future. Daimler is going very strong on that and others will follow. As for the €90 per gram fine that OEMs could be liable for, if they exceed the limits – for that, you can buy a lot of technologies to make the engine more efficient."
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