Electronics drive truck design

Dec. 28, 2000
If you thought electronic controls have done a lot for truck diesel engines, just wait until you see what will happen from now through the early years of the 21st century. That's the word from David F. Merrion, senior vice president of engineering at Detroit Diesel Corp. His company set the pace for the swing to electronic controls by introducing its first DDEC electronic control system for installation on existing diesels in 1985. In 1987, the company unveiled its Series 60 engines, the industry's first diesels designed for full electronic control.
If you thought electronic controls have done a lot for truck diesel engines, just wait until you see what will happen from now through the early years of the 21st century. That's the word from David F. Merrion, senior vice president of engineering at Detroit Diesel Corp. His company set the pace for the swing to electronic controls by introducing its first DDEC electronic control system for installation on existing diesels in 1985. In 1987, the company unveiled its Series 60 engines, the industry's first diesels designed for full electronic control. Among other things, electronics have helped deliver exhaust emission reductions as the federal Environmental Protection Agency (EPA) and other regulators have steadily called for cleaner air.

By 1998 the EPA is requiring a reduction in emissions of oxides of nitrogen (NOx) from the current limit of five grams per horsepower hour to four grams. While the reduction of one gram per horsepower hour may not sound like much, it amounts to a 20% cutback in NOx emissions. Despite the scope of the change, Merrion and his counterparts at other diesel manufacturing companies have indicated they will be able to measure up.

Last year, the electronic controls took over management of many major components in trucks. In rapid succession systems that deliver some form of automatic gear shifting were introduced. Most of the schemes entail the truck's engine doing the "thinking" behind the shifting.

"Communications, in general, is now a major part of our efforts," said Merrion. "Moving information through truck and engine has been a big goal of our program. The requirement of antilock brakes for trailers will increase the importance of communications between tractor and trailer.

"In-truck diagnostics has been a benefit of our electronics campaign. Upcoming is on-board engine oil analysis, which will tell the driver when he has a problem on the road. The more sensors we can put in the rig, the more information we can deliver."

New emission rules

The year 2004 could be the big one for a number of engine control ideas. The EPA has ordered a major tightening of exhaust emission rules for that year. A number of other programs, some related to emissions control and others only remotely connected, will top the truck news through the next seven years.

Much of the news will be reports on work done under a "statement of principles" agreement signed in 1995 by the EPA, the California Air Resources Board (CARB) and eight members of the Engine Manufacturers Association., including Detroit Diesel and Navistar (see Emission Standards to Tighten by Century's End, October 1996, p 50). Those who signed promised cooperation in meeting the 2004 standard, which calls for NOx emissions to be cut from 1998's four grams per horsepower hour to two grams by 2004.

Signers of the agreement took several months to work out details. Working together, they developed targets for the new national emissions standards that will dramatically reduce oxides of nitrogen and hydrocarbon exhaust emissions. Participants praised the agreement as an end to "assuming traditional combative positions" and "a start of working together to develop a joint proposal that makes sense for everyone involved."

NOx--chief target in the 2004 emissions revision--is a colorless gas that can be formed by the burning of fuel in a diesel engine. It results when oxygen and nitrogen from the engine's intake air form a bond. The NOx emissions, along with gaseous hydrocarbons combine in the atmosphere to form smog, or ground-level ozone.

Federal and state governments have taken steps to limit NOx emissions from their various sources. For instance, motorists in many metropolitan areas are encouraged to limit their driving on days when ozone formation is particularly likely. By 1998, the heavy-duty diesel industry will have reduced NOx emissions by 87% from uncontrolled levels, and they will be almost cut in half again in 2004.

Merrion said Detroit Diesel continues to develop a 2004 plan, without releasing complete details. The company is looking closely at some widely favored ideas. Two of these are improved turbocharging and exhaust gas recirculation.

Meanwhile, Navistar says its plan has an hydraulically actuated, electronically controlled unit-injector fuel system that manages fuel injection, timing and pressure. Interior refinements of the firm's engines and engine controls are other exclusives.

Catalytic converters also are mentioned as a possible solution with one from Mercedes-Benz getting special attention. But the main focus of the 2004 program is diesel fuel with some form of special "clean" diesel being discussed, despite the fact that a "clean" diesel drew objections from truckers in California were it has been used as an anti-air-pollution plan. "Alternative" (nonpetroleum) fuels are getting little attention in the 2004 effort to date. Merrion said they have yet to catch on in the mid-sized trucks often used in cities.

Kelley is a truck writer based in Dearborn, Mich. You may write him in care of the editor.