International's Engine Group recently revealed its strategy to get over the next two emissions hurdles to analysts and press at its Melrose Park, IL, headquarters. It includes digital valve technology and camless diesels.
The first new engine will be launched in 2001, a high-speed, new technology 4.5-liter V6 diesel designed to complement the company's high-volume V8, the 7.3-liter T444E. A new 6.0-liter V8 will ultimately replace today’s 7.3 – probably in the 2004 timeframe.
The new engines will be the first to incorporate the Sturman digital valve technology that provides a quantum leap in the control of fuel injection. Allied with International’s hydraulically actuated unit injector (HEUI) technology, the Sturman valve allows a smaller, less expensive injector that better fits into a 4-valve head and provides higher precision and control in the amount and the timing of the fuel injection.
The V6 will thus have better fuel economy and performance than its relatively small size would suggest. It will be an option for the mid-sized Expedition sport utility from Ford and the lighter of the full sized pickups. The 6.0-liter V8 will be launched the following year and is expected to have 90% parts commonality with the V6 and come with similar performance and economy advantages.
Although some of the technology will migrate to the 7.3 – it was suggested that the Sturman injector will add 40% to the clutch engagement torque alone -- within only a few years the new V8 will replace today’s 7.3-liter.
The digital valve technology was not explained in detail. However, Eddie Sturman, the founder of the technology company that bears his name, explained it is an adaptation of a 30-year-old aerospace system that has been brought to the automotive arena. Sturman Industries, the Colorado-based high-tech company is partnering with International in its development of new engine control systems -- both fuel and air handling systems -- using technology that controls hydraulic pressure digitally. This gives a level of injection control impossible to this point, with the ability to use pilot and after injection bursts of fuel that tailor the combustion process very precisely. The result is more power and better economy with more accurate emissions control.
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The technology is called cross-platform, so expect to see the same digital valve and injector setup on International's 466/530 in-line six-cylinder engines. Since there is room to expand the engine further, there may be an increased-displacement I-6 from this family down the road. With the ability to increase the power from these new V6/V8s and smaller I-6 engines through the exclusive combustion control, International sees itself expanding in to new markets down into the lighter pickups and SUVs from Ford up to over-the-road regional Class 8 units.
The real potential will be realized through the integration of ultra-precise fuel control with the same technology to control air management through the engine’s intake and exhaust valves.
By using hydraulic pressure and digital control, it is possible to eliminate the camshaft that has been integral part of the 4-cycle engine ever since the turn of last century. Despite the hundred-year development of the camshaft, the conventional valvetrain has major limitations. But after a few years of experimenting with the camshaftless engine, International and Sturman believe that with exhaust gas aftertreatment, future International diesels can be 50% cleaner than compressed natural gas engines.
No-camshaft valve actuation has become the holy grail of the engine designers in the last few years. To date, two technologies have emerged: electro-magnetic and electro-hydraulic. In the first, powerful magnets and electric fields provide the force to actuate the inlet and exhaust valves. In International's case, the oil pressure from the HEUI injection system and the precise Sturman valve control provides the force. Automobile engine designers are working with the magnetic technologies but are experiencing control problems that often lead to valves breaking off. Sturman points out that the hydraulic system is proven – there are more than a million HEUI engines running today – and hydraulics offer 20 times the force to open the valves against the diesel’s higher combustion pressure. Also, since hydraulic pressure provides the force, its control allows for a very soft landing of the valves against their seats, giving increased durability even over a conventional camshaft setup.
Citing just some of the features, International vp of engineering Pat Charbonneau said that hydraulic, no-cam valve action allows for completely variable valve timing, lift and duration -- varying valve overlap to engine speed and power demand is simple to do. Additionally, software control can open and close the valves multiple times during the cycle. It means the engine can be run as a power producer or a retarder with no additional hardware and the function can switch within one engine cycle making for extremely precise cruise speed settings. Valve control means additional economy and emissions control through cylinder cut-out when you don't need them.
In practice -- and in the prototype shown powering an 8100 International at the Melrose Park, IL., engine-plant reveal -- the new technology dispenses with camshaft, cam follower, pushrod, rocker, rocker shaft and pedestals. Instead a valve assembly sits on top of the in-head valves. On the cutaway heads the technology was shown compared with conventional valve actuation. Even in prototype form, there was only around a three-inch additional height requirement.
These heads featured a two-valve layout. But the smaller injectors that come with the Sturman digital valve technology will allow for four-valve per cylinder heads with the relatively small valve actuation blocks on top. Oil pressure from the low-pressure engine-oil common rail is used to actuate the valves at around 3,000 psi with Sturman digital valves controlling the flow and the valve position.
Additional benefits coming from the camless technology include weight and complexity savings from the elimination of the cam, ability to repackage engines more compactly and the addition of a retarder with no weight penalty.
The engines are claimed more powerful and more economical while delivering lower emissions. Early indications are that the torque will be much higher – up to 40% more at clutch engagement speed for instance – with the adoption of the technology.
Charbonneau said that there would not necessarily be cost savings from the elimination of the valvetrain components, but the addition of many features would mean more benefits at little or no extra cost.
Combining the advantages of the digital air and fuel management with exhaust gas aftertreatment via a regenerative trap gives diesel a clear advantage in emissions performance over other currently available low-emissions technologies, said all presenters at the briefing. Most recently, compressed natural gas (CNG and partner LNG) have been held out as the emissions-friendly fuel that will be necessary to meet 2007 regulations and inner-city requirement in EPA non-attainment areas. But Charbonneau said that International's diesel technology is capable of beating CNG hands down in the particulates/NOx as well as unburned hydrocarbons stakes.