Diesel engine sales are up for 2004. Markets buying diesel engines at a record pace include trucking companies, the agriculture industry, heavy industry, and even consumers who are tired of the paying a high price for gasoline for their trucks and SUVs. But the continued success of diesel engines also magnifies a pollution problem that diesel engine companies have been scrambling to solve.

EPA regulations

The EPA says that long-term exposure to diesel fumes is likely to pose a lung cancer hazard and that the particulate emissions from diesels are associated with increased risk of heart and respiratory problems. The agency has instated an aggressive, multitiered schedule of regulations designed to force the diesel industry to produce cleaner engines.

With sales on the line, diesel engine companies like Cummins realize that they can't afford not to meet EPA regulations on time. Caterpillar, another of the top diesel engine players, recently celebrated its success with its Advanced Combustion Emissions Reduction Technology (ACERT) program, a full-system approach that will help Cat produce clean diesel engines that will reduce emissions 90% by 2007. John Deere has made a similar announcement with its PowerTech Plus industrial diesel engines.

Record sales

Meanwhile, Cummins sales are on a record pace in 2004. For pickups, Cummins sold 130,000 engines to Dodge for its diesel-powered Ram last year and is on track to set record sales of at least 150,000 engines in 2004.

Mike Brinker, director of industrial sales for Cummins, says optimism abounds at the company these days. “Everything was up for us in 2004. Engines for trucks, farm tractors, telehandlers, power generators, heavy machinery — you name it. This year was a record year for us, and we expect 2005 sales to look good too,” he says.

Brinker says Cummins isn't about to let the EPA regulations slow it down. “Already, the Cummins QSM engine is the world's first engine to be certified for Tier 3, six months ahead of the EPA's January 2005 deadline,” he says.

Cummins and its competitors are aggressively investing in the development of new combustion technology, including advanced electronic controls and high-pressure common rail fuel injection. “Our Tier 3 engines will have an in-cylinder solution that reduces nitrogen oxides by 40% without the use of expensive external hardware,” Brinker says. “With the certification of the QSM completed early, our development can focus on further improvements in fuel economy and reliability.”

Cummins and its competitors will rely on more after-treatment systems as emissions regulations become even stricter in 2007 and beyond. With that challenge in mind, Cummins hopes its Emissions Solutions division will be able to provide after-treatment particulate traps and catalytic ceramic filters not only for its own engines, but also for a potential $10 billion industrywide market for emissions reduction products.

What makes a clean diesel?

It takes technology to make diesels run cleaner. The Diesel Technology Forum, an industry-supported communications group, describes the following innovations:

Glow plugs typically comprise a heating coil in a metal tube closed at one end and filled with electrically insulating ceramic powder. They ensure that compression temperature is high enough for proper ignition of the injected diesel fuel. When the glow plug is electrically energized, its heated portion reaches a surface temperature of more than 1,832°F within a few seconds.

Electronic controls activate mechanical switches that allow precise amounts of fuel to flow from the injector into the cylinder.

Common rail fuel injection is an advanced fuel pump technology that is part of the new fuel-control system in clean diesel engines. By directly feeding the injectors from a single fuel pump, an electronic system can precisely control the pressure and timing of fuel injection regardless of engine revolutions per minute. High fuel pressure produces a fine mist of fuel that burns better and cleaner in the combustion chamber.

Variable injection timing is a new fuel-control system in which an electronically controlled, high-pressure fuel injector releases the precise amount of fuel at the moment of maximum compression (when the piston reaches the top of the cylinder).

In an improved combustion chamber configuration, the cylinder head is shaped to provide the proper space in which fuel/air mixture will ignite and burn most effectively, creating maximum power stroke.

Turbocharging uses energy from the engine exhaust to boost performance. The turbocharger consists of a set of two connected fans, or turbines, that recycle the energy from wasted exhaust gases. In gasoline engines, it takes 9,000 gal. of air to burn 1 gal. of fuel. For diesels, it takes 20,000 gal.

Ultralow sulfur diesel fuel (ULSD) is highly refined for clean, complete combustion and low emissions, enabling the use of emissions treatment systems. The sulfur content of ULSD ranges from 15 to 30 parts per million (ppm). Regular diesel has a maximum of 500 ppm of sulfur.

Particulate traps are filters that collect particulate matter as the exhaust gas passes through and can reduce particulate emissions by 80 to 90%. The CRT particulate filter can burn off soot at 482°F in the presence of a precise amount of nitrogen dioxide. More than 70,000 CRT filters are in operation on diesel vehicles around the world. Some of these filter systems have more than 1,000,000 miles of reliable service.

Oxidation catalysts are the second part of the emissions control system that prevents clogging in the particulate filter by attracting excess soot from the exhaust. Some catalysts — such as selective catalytic reduction devices and nitrogen oxide absorbers — focus on nitrogen oxides and can reduce these emissions by 25 to 50%.