By: Ken Kelley
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.
