Volvo Says Its '07 Emissions Gear Will Build On 2002's
More EGR and diesel particulate traps will be among changes
to meet stricter regs; '10 engines may get SCR.
Tom Berg
Equipment Editor
Volvo Powertrain said its emissions-reduction strategy for 2007-model diesels to be produced for Volvo Trucks North America will include "heavy" exhaust-gas recirculation and particulate traps. It also said it is leaning toward adding selective catalytic reduction for 2010 engine models. Similar technology will be used in engines made for sister company Mack Trucks, though details of those will come directly from Mack, said executives at the Gothenberg, Sweden, headquarters of Volvo Truck Corp., owner of the two American truck builders as well as Renault Vehicles Industriels in France.
Volvo's strategy to build on 2002/04 designs thus parallels that of its North American competitors, who previously announced that they would add diesel particulate filters and other refinements to their current engine models to meet the federal Environmental Protection Agency's tighter emissions regulations for 2007. Also like competitors, Volvo would not estimate the extra cost of its '07 models, though customers of all builders fear price hikes will be as much as or more than for '02/04 heavy duty diesels - an average of $5,000.
2007 and later-model Volvo and Mack engines for North America will be assembled at a new plant in Hagerstown, Md., near where Mack engines and gearboxes are now produced. The two brands will use common blocks but retain separate identities through differing horsepower and torque ratings and operating characteristics. The companies' separate philosophies of engine design will be preserved through use of different pistons, valves and crankshafts installed in common blocks.
Blocks and other parts will be cast and machined at Volvo Truck Corp.'s foundry in Skovda, Sweden, then shipped to Hagerstown for assembly by automated equipment and carefully trained workers. Displacement sizes and ratings will not be disclosed until later, executives said. But they hinted that the new engine "family" would include a 16-liter in-line Six introduced last year by Volvo for the European market. It is now offered in 560- and 610-horsepower versions with features like advanced electronics and combustion design, overhead camshafts and rear-mounted timing gear. Twelve-liter engines now made separately by Volvo and Mack will be replaced by new models using a common block that will probably be close to the current displacement.
VG Turbo & Particulate Trap
Engine designs for '07 and later will include higher pressures in cylinders and fuel injection systems and advanced turbocharging, engineers said. Volvo Trucks will drop its current V-Pulse system that uses a simple turbocharger, and instead employ a variable-geometry turbo to gain better management of air compression and flow throughout the operating range. The VG turbo will also produce better throttle response - a characteristic of VG turbos now used by other North American engine builders.
2007 regulations concentrate on reducing particulates, which is why every engine builder will use a diesel particulate filter, or DPF. Volvo's DPF is an "active" type that will strip microscopic pieces of soot from the exhaust and periodically burn them off with small injections of diesel fuel. Accumulated ash will have to be removed every few hundred hours of operation, though exact intervals will be determined by operating conditions. Engineers said that this servicing should be done when a truck comes in for an oil change, though it would be required every seven or eight changes.
Servicing would cost about $150 in labor because a technician will have to remove the DPF from a component that will include an oxidation catalyst and muffler. He could clean the internal trap, or replace it with a new trap or one that's already cleaned. On most trucks, this component would be in the exhaust stack, but it could be mounted on the frame, and test units have included separate DPFs. The DPF's canister will have electrical and fuel-line connections.
2010 regulations will demand further reductions in nitrogen oxides, or NOx, and Volvo tentatively plans to accomplish this through use of selective catalytic reduction, called SCR. This process injects a solution of 32.5% urea additive and 67.5% deionized water - referred to as AdBlue - into the exhaust ahead of an oxidation catalyst. AdBlue chemically breaks down NOx into nitrogen and water. Volvo and other builders will use SCR to meet '06 European regs; AdBlue in amounts of 5 to 6% to that of diesel fuel burned will be needed to do the job. In America, use of the particulate filter and other changes by 2010 means less AdBlue - only about 1% - will be needed.
However, Volvo executives said they aren't yet sure that the U.S. EPA will allow use of SCR. EPA has expressed reluctance because its regulators aren't assured that AdBlue will be widely available, and it doesn't trust truck operators to refill the AdBlue tank when it runs low. Builders say the 1% ratio means amounts would be so small that AdBlue could be distributed in jugs and sold off shelves like antifreeze; no infrastructure of underground tanks and pumps would be needed. And if a driver or fuel pump jockey fails to fill the AdBlue tank, sensors will detect it and electronic controls can order a cut in power and eventually shut down the engine.
Volvo and other engine builders are working through industry associations to lobby the EPA into accepting the SCR approach, and need a decision by the end of next year so they have enough lead time to get '10 test engines into the hands of customers. Theoretically, EPA shouldn't have to approve SCR, but it could decide to officially discourage or prohibit it if its questions aren't satisfactorily answered.
Other Issues
Another requirement of the '07 regs is closed crankcase ventilation to eliminate oil fumes escaping into the atmosphere. Volvo plans to route oil fumes through a cleaner and then burn cleaned air in the cylinders. The cleaner is designed to work for the life of the engine without servicing. Caterpillar said it will send fumes into the exhaust and thus extend its philosophy of burning only "clean" air in cylinders.
Executives at Volvo and other builders said they will have preproduction '07 diesels available for purchase by sometime next year. This should prevent the problems seen in the short time leading to October '02, when fleet managers complained that they couldn't get newly configured engines for on-road testing.
Fear of the '02 engines, along with higher prices of trucks they were to power, caused the massive "pre-buy" in the months prior to October '02, when new regs went into effect for most U.S. builders. This was followed by a precipitous fall-off of orders.
Orders are now strong, but builders think some are due to another pre-buy. They hope to avoid another downturn by putting engines in users' hands sooner.
Aside from reported problems with EGR gear and other issues with the '02/04 diesels, another maintenance-oriented problem has surfaced: more heat in engine compartments. Changes to the '02 engines, and to those diesels produced by builders for whom the deadline was January '04, resulted in higher heat rejection. This had to be dealt with by stronger cooling systems, which contributed to the price hikes for '02/04 trucks. But fleet managers complain that heat radiating off engine blocks, turbochargers and exhaust-gas coolers has caused high temperatures under the hoods of these trucks. Temps are greater than what builders said they'd be, some managers complained at a recent meeting of the Technology & Maintenance Council of ATA. One manager said heat test strips showed temps as high as 350 degrees Fahrenheit.
This problem might be worse with '07 engines because heavier doses of exhaust gas - to reduce cylinder temps and cut NOx emissions - will mean even more heat rejection. Volvo, for example, says its '07 diesels will throw off 10% to 30% more heat than now; Caterpillar says its non-EGR'd ACERT diesels will reject 10% more heat because Cat will use retarded timing to deal with NOx cuts in '07. Much of this extra heat will be carried off by cooling systems, some of which may have to be further enlarged or otherwise increased in capacity. But some heat will be radiated, again raising underhood temps.
Price rises for trucks with '07 and later engines will be partly due to cooling systems changes, say truck makers.
Meanwhile, Detroit Diesel says it plans to replace EGR gear on some of its early '02 engines because of cooler and fitting failures. The water-to-gas coolers have leaked and some connections failed, an engineer explained, and these will be replaced for owners who bring in trucks with affected engines. DDC issued a service bulletin on the situation earlier this year.
