Just as heavy-duty truck owners became accustomed to new cooling and exhaust systems driven by the Environmental Protection Agency’s 2004 diesel engine
Just as heavy-duty truck owners became accustomed to new cooling and exhaust systems driven by the Environmental Protection Agency’s 2004 diesel engine emissions guidelines, another regulatory round spawns the next generation of power packages. Caterpillar Power Systems, Cummins Inc., and integrated truck OEMs outlined plans to bring next year’s engine offerings into compliance with EPA 2007 guidelines during World of Concrete (Las Vegas, January); ATA Technology and Maintenance Council meeting (Tampa, February); Mid-America Trucking Show (March, Louisville), and Waste Expo (April, Las Vegas).
Compared to benchmarks for 2004 EPA-compliant models, the 2007 engine guidelines call for a 90 percent reduction in emissions of oxides of nitrogen (NOx) and particulate matter or soot. If exhaust gas recirculation was the centerpiece of 2004 emissions guideline compliance, diesel particulate filters and active/passive regeneration are shaping up as the signature elements of EPA 2007 engine technology. In typical engine schemes, the DPF: 1) replace mufflers and convert NOx into carbon dioxide and water; and, 2) capture soot which is then oxidized, or burned off, by active or passive regeneration cycles. Adding more than 100 lbs. to truck weight Û and filter-cleaning intervals to routine maintenance cycles Û the DPF will likely be vertically mounted behind the cab for mixer, dump, and block-hauling applications. In tractors for cement bulk tankers and most conventional on-highway applications, the DPF can be mounted under the hood.
The EPA 2007 engines attain sharply lower NOx and PM emissions benchmarks through the use of ultra-low sulfur diesel, which is set for retail availability this October. The EPA standard for allowable sulfur content for this diesel is now 15 ppm (hence the fuel designation S15) compared to the previous U.S. standard of 500 ppm. Despite availability concerns for the new diesel, most engine suppliers report they are now working closely with truck makers to deliver vehicles equipped with 2007-spec engines. In a few markets where ultra-low sulfur diesel is available, a limited number of truck operators are putting the new engines to the test.
What will this compliance cost? The best indicators so far are from Volvo Trucks and Mack Trucks, which in customer alerts earlier this year noted 2007 power package-rooted premiums of $7,000 and $7,500, respectively, for on-highway models. The companies have not indicated what premiums the concrete and aggregate-suited VHD and Granite series will carry.
Toward 2007 EPA-compliant engines, the company has announced diesel particulate filters and exhaust gas recirculation (EGR) for MidRange and Heavy-Duty models, including the ISL and ISM engines often spec’ed in mixer, block-hauling and dump trucks.
The ISL and ISM will use EGR coupled with exhaust aftertreatment provided by the integrated Cummins Particulate Filter and a crankcase ventilation system. A Fleetguard Enviroguard coalescing filter captures and filters crankcase emissions. Both the engine and aftertreatment are linked by a single electronic control module.
The particulate filter is designed to last the life of the engine. Maintenance will be required to remove the ash content, and intervals varying by duty cycle could be up to 400,000 miles. The Enviroguard coalescing filter captures and filters crankcase emissions, and will require replacement every third or fourth engine oil change, intervals of which will remain the same for 2007 models.
The engines will use the sliding-nozzle Variable Geometry Turbocharger (VG Turbo), which doubles as an exhaust brake with increased braking power in 2007. Also new in 2007, the VG Turbo features a new electric actuator with reportedly faster response and improved precision in adjusting airflow to the engine.
The ISL will use high-pressure common rail fuel systems, enhanced for 2007 with higher injection pressures to optimize fuel economy and increase performance. The engine, featuring an optional compression brake, has boosted top horsepower/torque ratings up to 365/1250. The ISM will maintain an established range of ratings.
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As one of the earliest companies out of the gate to announce Î07-compliant engines, Mack unveiled the MP7 lineup at an October 2005 world sales event in Las Vegas (see Concrete Products, November 2005, p. 36). Earmarked for the Granite series, the 11-liter MP7 model is available in the three Mack engine families Û Econodyne, Maxidyne and MaxiCruise Û in six horsepower ratings between 325 and 405, with torque ranging from 1,260 to 1,560 ft.-lb. Although initially offered in EPA Î04-compliant configuration, the MP7’s base architecture represents the heart of Mack’s solution to the 2007 EPA emissions regulations, since it will be adaptable with a diesel particulate filter (DPF).
In both highway and vocational applications, customers can expect a significant improvement in fuel economy in the MP7, according to the manufacturer. Oil drain intervals are currently estimated at 30,000 miles for standard highway applications and 300 hours (or 15,000 miles) for most construction applications.
In addition to the MP7, Mack also announced plans to have the second member of its new engine family Û the MP8 Û available in 2007. Designed for those requiring higher horsepower, the MP8 is a 13-liter engine with ratings from 415 to 485 hp, matched to torque levels from 1,540 to 1,700 lb.-ft.
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VOLVO TRUCKS NORTH AMERICA
New for 2007, the D11 and two larger bore engines use high-efficiency cooled exhaust gas recirculation (EGR) in combination with a diesel particulate filter (DPF) to reduce emissions of oxides of nitrogen (NOx) and particulates.
The company’s EGR system uses three advanced components aimed at NOx emission reduction: sliding nozzle variable geometry turbocharger (VGT) with electronic actuation provides the required EGR pressure with precision; hydraulically controlled EGR valve controls and regulates the amount of exhaust gas required; and delta-pressure EGR flow sensor measures changes in EGR flow and communicates to the VGT actuator and EGR valve through a closed-loop electronic system using the Vectro engine management system.
The DPF system contains a catalyst and particulate trap. Soot from the engine exhaust is trapped within a catalyzed ceramic monolith with a Volvo-specific metal coating. The DPF system also acts as a muffler.Volvo offers two choices for DPF installation. The primary choice is Volvo’s Compact DPF, which mounts to the frame under the cab on the right side of the truck. This configuration allows a simple vertical straight pipe behind the cab. A DPF is also available for back of cab mounting, for short wheelbase vehicles where space is at a premium. The DPF system has been designed to operate with a primarily passive regeneration cycle, depending on duty cycle, in order to optimize fuel economy.
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Detroit Diesel Corp. is set to launch a 2007 EPA-compliant MBE 4000 engine for Freightliner, Sterling and Western Star models geared to on/off highway applications, along with two other redeveloped power packages for conventional medium (MBE 900) and heavy-duty (Series 60) trucks.
The engines will carry an aftertreatment system to replace the exhaust system’s muffler assembly. The new system reduces the amount of particulate emissions and includes a Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF). During normal operation, exhaust heat and the catalyst work together to oxidize the soot. Additionally, optimized exhaust gas recirculation will be applied to treat NOx, while the next generation electronic control unit Û DDEC VI Û will offer increased microprocessor power and memory, along with enhanced diagnostics. DDEC VI is capable of monitoring and managing all engine functions including the aftertreatment system required for 2007 emissions.
The 2007 MBE 4000 will also use a new fuel system with multi-injection capability to help meet emissions targets while maximizing economy and performance. The design reportedly enables the engines to run smoother and improves the overall sound quality. The MBE 4000 ‘s power range runs from 350 to 450 hp with 1,250 to 1,650 lb.-ft. torque. The engine can also be specified at 370 hp with 1250 lb.-ft. torque. For weight sensitive applications, the MBE 4000 now offers 450 hp rating with 1650 lb.-ft. torque. The MBE 4000 comes with a standard engine brake that provides up to 370 braking horsepower.
The 2007 MBE 4000 retains its front engine power take-off and rear engine power take-off options, enabling Detroit Diesel to extend the engine’s presence in mixer, block & brick delivery, and dump truck applications.
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INTERNATIONAL TRUCK AND ENGINE
The company will offer Caterpillar and Cummins power packages in its 2007 heavy duty models, leading up to an October 2007 launch of a new line of big bore engines. The 11 to 13-liter class MaxxForce engines will initially be offered in the mixer and dump-suited 7600 and 7700 models, and subsequently in the company’s 5000 PayStar series.
The engines offer air- and fuel-management technologies and exhaust gas recirculation (EGR) systems with the addition of advanced aftertreatment systems necessary to deliver performance while meeting 2007 U.S. EPA emissions standards. The engines feature a lightweight yet virtually indestructible block cast from compacted graphite iron (CG Iron), a spec proven by a German company, MAN Nutzfahrzeuge, International has tapped to collaborate on design, development, sourcing and manufacturing.
Compared to gray iron Û currently the most common material from which truck engine block castings are made Û CG Iron is 70 percent stronger and 40 percent stiffer, with double the fatigue limit, International engineers note. A precise amount of magnesium is added to the base iron in a highly controlled process to create a new compound that is harder than traditional gray iron, increasing resistance to stress cracks.
Because CG Iron has higher inherent strength, castings don’t have to be as thick and heavy in order to achieve the desired durability required for heavy-duty diesel operation, International contends. This provides weight savings of several hundred pounds versus an engine block cast from gray iron of equivalent strength.
Other manufacturer-cited features of the MaxxForce line include:
- Flexible and responsive direct-injection, high-pressure common-rail electronic fuel system capable of multiple injection events
- Durable single-overhead-cam actuating four valves per cylinder and roller rocker arms
- Rugged gear-driven air compressor and power steering pump
- Rear-gear train and pad-mounted accessories designed for low noise
- Full 2007 EPA emissions compliance based on the company’s Green Diesel Technology
Along with the MaxxForce roll out, the company is expanding its Green Diesel Technology platform, which encompasses research, development and field testing of improved diesel emission solutions. Green Diesel vehicles utilize the benefits of a catalyzed diesel particulate filter and ultra-low sulfur diesel fuel.
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CATERPILLAR POWER SYSTEMS
Based on the company’s ACERT technology platform Û combining air management, precision combustion, advanced electronics and effective aftertreatment Û the 2007 engine line features two major new components and additional processes:
Clean Gas Induction (CGI)
A refined combustion technology reduces both oxides of nitrogen (NOx) and particulate matter in the cylinder. CGI is a proprietary ACERT process that draws off a small amount of noncombustible gas after it passes through the engine’s aftertreatment system. The gas is then cooled, blended with more incoming cool, clean air and returned to the combustion chamber.
CGI will enable the offering of 2007 heavy duty engines that provide the same level of fuel economy as current engines, while mid-range products will deliver up to 4 percent improved fuel economy, Caterpillar officials report. Horsepower ratings and service intervals will remain the same as those of 2004 engine models.
Diesel Particulate Filter (DPF)
Design of the Caterpillar-manufactured DPF employs wall-flow technology Û a ceramic brick substrate allowing the particulate matter, or soot, to be captured in cells within the wall. The exhaust gas then exits as clean exhaust consisting of carbon dioxide and water. The Cat DPF employs active regeneration, which means that when the temperature of the engine is not sufficiently high to oxidize (burn) the soot that collects in the DPF, the exhaust gas is heated by auxiliary means. The design enables automatic regeneration under all conditions without any driver involvement.
Cat Regeneration System (CRS)
As any DPF requires a temperature up to 1,200?F to regenerate, the manufacturer’s DPF will use CRS, a process similar to a gas-fired furnace in which fuel is introduced into a closed combustion chamber, rather than being injected directly into the filter. When the engine electronic control module detects soot buildup, CRS automatically uses only the amount of fuel necessary to heat and oxidize the soot.
DPF soot removal
Since a certain amount of ash collects in the DPF, it needs to be cleaned periodically. The Cat DPF can be serviced without removing it from the vehicle. A special ash collection tool results in less downtime, taking roughly the same time as an oil change. The service interval is projected to be approximately 200,000 to 300,000 miles, depending on application.
As a company-manufactured part, the DPF is serviced through Cat and authorized truck dealers. Covered by the manufacturer’s base warranty, the filter provides sound attenuation, as it replaces a conventional muffler on the engine, and eliminates the need for a diesel oxidation catalyst.
The 2007 Caterpillar on-highway engine line comprises C7, C9, C13, and C15 Û all equipped with the ACERT technology.
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EPA DIESEL ENGINE EMISSIONS BENCHMARKS
|October 2002/January 2004||January 2007|
|0.10 g/bhp-hr. *||0.01 g/bhp-hr.|
(Oxides of Nitrogen)
|2.0 g/bhp-hr.||0.2 g/bhp-hr. **|
|0.4-0.5 g/bhp-hr.||0.14 g/bhp-hr. **|
|* g/bhp-hr. = grams per brake horsepower-hour|
|**NOx and NMHC requirements will phase in between 2007 and 2010.|
ACTIVE VS. PASSIVE REGENERATION
Volvo Trucks’ DPF has been designed to operate with primarily passive regeneration, depending on duty cycle, to optimize fuel economy. In passive regeneration, soot is stripped out of the DPF’s ceramic monolith in an ongoing catalytic reaction process that uses no additional fuel. The process leaves a fine ash that remains trapped in the DPF. Regulations call for the filter to operate for more than 100,000 miles before it needs to be cleaned of ash for the first time, with subsequent cleanings at intervals of 150,000 miles or more during routine maintenance.
In duty cycles that do not generate a sufficiently high temperature, including stop-and-go or local delivery, the DPF may occasionally need to undergo active regeneration, whereby a small amount of diesel is introduced into the exhaust stream at the turbocharger outlet. In the Volvo design, the fuel travels in a mist to wet the DPF’s pre-catalyst, which causes a chemical reaction that raises DPF temperature to the level required to oxidize and burn off the soot. Active regeneration takes approximately 15 minutes and, other than an indicator light in the instrument cluster, is not apparent to the driver. The process consumes approximately one-half gallon of fuel and can be postponed by the driver if operational reasons dictate.