Pollution controls on new spark-ignited motors for lift trucks
will make them more like auto engines: more fuel efficient, but more complicated to maintain.
Many U.S. lift truck manufacturers are counting the days until January 1, 2001. They're not interested, however,
in a rollover to the "true," new millennium. Rather, they're concerned about how to meet exhaust emission
limits that begin phasing next year in California.
Developing new forklifts with cleaner running engines isn't just an issue in California. By 2004, the same or
similar air pollution controls probably will be on new industrial trucks sold in all 50 states.
With cleaner engines in these new lift trucks, users can expect to achieve cost savings on fuel usage. Fitted
with emission controls and run by computer logic systems, the engines will be more expensive to manufacture. Whether
those costs will be passed on to forklift purchasers remains to be seen. Meanwhile, maintenance of computerized
and tamper-proofed engines will be more complicated to perform, though necessary less often than now. The days
of making quick adjustments of engine idle speeds and the like with a screwdriver are near an end.
| California's four-step phase-in of controls |
 |
| California rules require each manufacturer to increase the percentage
of its forklifts that comply with tough emission limits to increase in stages, from 25% in 2001 to 100% in 2004. |
California's regs target forklifts with spark ignited (SI) internal combustion (IC) engines made after January
1, 2001. The rules cover only SI/IC engines that run on gasoline, propane, or natural gas fuels. (Diesel-fueled
engine emissions are regulated separately by the federal Environmental Protection Agency). Engines made before
2001 are not regulated.
California Air Resources Board rules will curb emissions of volatile hydrocarbons, nitrogen oxides, and carbon
monoxide. CARB wants a 75% emission reduction from levels typically emitted now. Roughly, that's a cutback from
12 g/hp-hr to 3 g/hp-hr of the total amount of hydrocarbons plus nitrogen oxides now released.
CARB rules will be phased in. For 2001 they impact just 25% of the total annual California market for SI/IC
forklifts. That's one-fourth of some 5,000 to 5,500 new trucks shipped yearly for use in the state, industry sources
note.
Each year thereafter, the percentage of new industrial trucks sold in California by each manufacturer with cleaner
engines meeting the emission standard goes up: to 50% of all lift trucks in 2002, 75% in 2003, and 100%, in 2004
(chart).
By 2004, moreover, if the federal government, as seems likely, goes along with the California approach, some
70,000 new SI/IC trucks used anywhere in the U.S. will have to be equipped with cleaner engines.
Some lift truck manufacturers, especially those in corporations with auto industry sister companies, are developing
their own cleaner engines. Many are canvassing third party engine vendors and control component suppliers, seeking
to obtain complying engines–certifiable to CARB standards–from these outside sources. A high level of secrecy surrounds
progress toward these goals.
Limiting emissions:
A third-party vendor's approach
IMPCO Technologies is one of the third party engine systems vendors developing
engine control and fuel systems as well as total engineered engine packages to limit tailpipe emissions. Under
its Spectrum program, the company has developed several classes of engine fuel and control systems for forklift
use. Primarily, these systems are for lift trucks running on LPG and natural gas fuels. But the company also is
developing gasoline and dual-fuel (gasoline or LPG) systems.
Its OMNI-AG engine systems, for example, are designed to use air/gas
valve technology for LPG or natural gas fuels. These systems are intended for compliance with CARB rules for the
years 2001-03.
More advanced OMNI systems use fuel injection technology instead of an
air/gas valve. Port injection (OMNI-PI) and central injection (OMNI-CI) systems have been developed. They aim at
meeting CARB's increasingly stringent rules through the year 2007, IMPCO says.
IMPCO planned to have these systems on display at its exhibit at the
CEMAT Show in Hannover, Germany, last month.
Diagrams of the OMNI technologies illustrated here demonstrate how the
complexity of lift truck engine systems will increasingly mirror those in autos. Like fuel injection for autos,
the more advanced CI lift truck systems have multiple input sensors. A sensor measures air temperature in the clean
air intake stream, for example. A MAP sensor determines manifold air pressure. A throttle position sensor helps
calculate load demands and engine timing. An oxygen sensor checks oxygen content in the exhaust stream and helps
set the correct fuel/air mixture. And so on.
Through an engine control module (ECM) and its computer logic, various
input signals are received and output factors are controlled, such as amount of fuel injected, engine speed and
timing, and some other engine functions. With data from a drive-by-wire throttle sensor option, the ECM can limit
or govern engine speed, for example.
|
As of Spring 2000, few, if any, lift truck makers appeared fully ready to market units with new engines, new
controls for California. One third party engine vendor was set, at press time, to unveil its progress on cleaner
forklift engines at the CEMAT Show in Hannover, Germany, late last month, however (see sidebar at right).
More expensive forklifts?
Everyone working on the emission control problem also recognizes that there will be added costs–at the manufacturer's
level–for new engine systems. One estimate pegs added costs at a bare minimum of $300 per lift truck to $800 or
more. Whether end users bear such costs remains to be seen, however.
CARB's stepwise, three-year phase-in for complying trucks makes pass-through of costs a particularly tricky
matter. Manufacturers will watch what their competition does before risking raising sticker prices.
Industry engineers also suggest that if, eventually, there are added costs in the up-front price, they will
be offset by savings on fuel in the long run.
What makes California's actions highly significant, says Industrial Truck Association past president Larry Borre,
"is that they are the warm-up for a single national regulation in 2004." The ITA exec and Nissan Forklift
vice president notes that the federal EPA is expected to enforce the same level of control over exhaust pollutants
as CARB will require.
As an industry and as individual companies, the manufacturers are committed to lowering emissions to control
smog formation and air pollution.
Meeting the 75% emissions reduction will be "challenging, but feasible," Borre adds.
For lift trucks powered by gasoline, the challenge is less daunting, industry experts say, than it is for propane
(LPG) fueled forklifts. Controls work on gasoline-fueled autos; similar devices should apply to LPG lift trucks.
Or so CARB argues.
Significantly, however, LPG lift trucks are as much as 70% to 80% of all SI/IC forklifts in the U.S. Almost
all of these trucks use old technologies such as a carburetor to regulate the air/fuel mixture. And they have an
open-loop fuel system that does little to limit emissions of unburned propane.
Commercial emission control technologies for gasoline-fueled autos include three-way catalytic converters, closed
loop fuel systems, electronic fuel injection units, and other devices. The three-way catalytic units reduce emissions
of hydrocarbons and nitrogen oxides plus they also cut down on carbon monoxide levels.
LPG forklift meets CARB's regs
California Air Resources Board and Southwest Research Institute have
tested an inline, 4 cylinder, 40 hp Nissan engine in a lift truck for compliance with emission limits. This power
plant is designed to run on gasoline or LPG (liquid propane gas) fuel. Emission controls on this engine included
a closed-loop fuel system and 3-way catalytic converter.
When tested on LPG fuel, this engine was equipped with other controls,
including an electronic engine control module, exhaust gas oxygen sensor, carburetor for air/fuel mixing, and an
LPG liquid fuel to vapor converter.
CARB/SRI results show a 97% reduction in emissions of hydrocarbons and
nitrogen oxides from the LPG engine. That reduction came after 250 hr of service in a lift truck. SRI used the
truck for 83 hr to move fuel drums and pallet loads. Then a grocery chain warehouse ran the vehicle up to the 250
hr point, moving empty boxes and pallets. "However, no great deal of heavy lifting was required," the
study notes.
|
Nissan's Sentra CA 2000 auto model won CARB recognition early this year for this gasoline vehicle's ultra low
emissions. The Sentra is the first auto model to get a zero emission credit rating by the California agency.
Even so, autos running on gasoline and driven at speeds up to 70 mph have engines that often perform far differently
than the same or similar engines in lift trucks at 10 mph or far less. And these performance differences complicate
achieving emission control limits.
Pointing to the Sentra's low emission level, however, Nissan Forklift marketing director Keith Allmandinger
says that implementation of similar air pollution controls for off-road, industrial engines will not lag far behind.
"Nissan is currently working on electronic fuel injection with an integral electronic governing system"
for its industrial engines that will meet and beat future clean air rules, he says. Research published last August
helps bear out the Nissan exec's statement (sidebar at left).
CARB has cited these results as support for the agency's view that manufacturers should be able to comply with
its rules.
Details, details
But, as Toyota Industrial Equipment's Dale Muhlenkamp says of CARB compliance, "The Devil is in the details."
Ensuring that engines will control emissions over their full, useful life is just one tough challenge requiring
detailed effort, says the Toyota dealer training and customer support manager. Packaging new emission control systems,
particularly for smaller IC trucks, into the spaces "under the hood" is another, Muhlenkamp adds.
CARB says that complying engine controls need to be very durable. The agency requires that 5,000 hr be the useful
life for controls on SI/IC engines.
Yale Materials Handling senior project engineer Mike Payton calls that a very tough standard. "I can't
overemphasize how huge a challenge it is to meet this durability requirement. And to do so in a cost-effective
way."
Using a rule of thumb that 1 hr of lift truck service equals 30 highway miles, Payton notes how 5,000 hr of
service translates into 150,000 highway miles for an auto. CARB is asking that forklift emission control systems
be 50% more durable than what's asked for highway vehicles, he says.
To meet the duty cycle standard that CARB requires, moreover, means that lift truck engine emission controls,
because of a normalized speed factor set by CARB, need to be "twice as robust as that required for the engine
in an on-highway, heavy-duty truck," Payton adds.
Two emission control technologies
|
 |
- Fitted with a catalytic muffler, engine sensors, and an electronic
control module, this engine control system from IMPCO Technologies adds increased computerization to a carbureted
forklift engine running on propane or natural gas fuel.
- Based on air/gas valve technology, this engine has sensors such
as those for MAP (manifold air pressure), RPM (revolutions per minute), and oxygen content in the exhaust stream.
- The sensors feed data to an engine control module that adjusts
engine parameters to limit exhaust emissions.
|
 |
|
Designed for central fuel injection, this engine control system
is more advanced than that above. And it's more like the controls under the hoods of today gasoline-powered autos
and light duty trucks.
- Propane fuel, for example, is thermally heated, then goes to
a pressure regulator and next to a fuel injector.
- An injected propane/air mixture then heads to the cylinder for
ignition.
- This injection system should be able to meet California emission
limits through the year 2007, IMPCO says.
Source:
IMPCO Technologies
|
Closed-loop fuel systems will likely be a part of the control package for both gasoline and LPG forklifts, say
many manufacturers' execs. These systems should deliver several advantages.
Mitsubishi Caterpillar Forklift America engineer Eric Fierson says there's "a potential for a 20% to 40%
fuel cost savings" from the systems. And they should have "reduced maintenance and improved performance,"
he adds.
At MCFA, the R & D effort includes developing modular fuel systems, including a module for dual fuel (gasoline
or LPG) trucks.
MCFA, Yale, and others are all taking a hard look at what their engineers call cutting edge technology for LPG
fuel injection. "Our industry," says Yale's Payton, needs "a company to step forward with a good
injection system."
There's one problem with developing a suitable LPG injection system, however: fuel contamination. LPG injectors
need to be "robust," says MCFA's Fierson. The contents of fuels, besides their propane component, vary
considerably from one LPG source to another.
Packaging pollution controls
Fitting new control devices into smaller IC lift trucks, meanwhile, is like "trying to stuff a bigger foot
into the same size shoe," suggests Toyota's Muhlenkamp. How do you "package" controls into the truck?
Controlling heat escaping from catalytic conversion units–heat which might otherwise be released to the operator
and/or to the surrounding environment–are among the design problems manufacturers must solve.
The heat release design problem is reminiscent of what resulted with some early autos with three-way catalytic
converters: Autos run until the converters were very hot, then parked over combustion sources, such as dead and
dried tree leaves, could set off fires.
Heat release from a lift truck run in a scrap paper application, for example, might pose a similar hazard unless
the design of the forklift and its emission control system guards against it, Toyota's Muhlenkamp says.
Tamper-proofed engines
Future forklift engines will be much like today's auto engines from the mechanic's perspective. The days of
simply turning up the engine idle setting with a screwdriver will soon vanish, suggests Yale's Payton. Emission
controls will be made tamper-proof, adds MCFA's Fierson. Diagnostics will be added to trucks. Lift truck maintenance
operations also will have to use more diagnostic gear to keep engines in compliance.
Indeed, these more electronically sophisticated engines and controls will further underscore the sometimes unmet
needs now for qualified technicians who can perform maintenance on lift trucks.
Lift truck users in California will experience the impact of CARB limits first, of course. They will be the
proving ground, the test track for much of what's expected to work elsewhere in the U.S. However, managers of forklift
fleets from Maine to Montana, from Alabama to Washington state would do well to watch what happens in the next
few years–before they're directly affected.
|
