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To reduce NOx emissions from a heavy-duty engine at low exhaust temperature conditions, the plasma-assisted SCR (Selective Catalytic Reduction) system was evaluated. The plasma-assisted SCR system is mainly composed of an ammonia gas supply system and a plasma reactor including a pellet type SCR catalyst. The preliminary test with simulated gases of diesel exhaust showed an improvement in the NOx reduction performance by means of the plasma-assisted SCR system, even below 150°C conditions. Furthermore, NOx reduction ratio was improved up to 77% at 110°C with increase in the catalyst volume. Also NOx emissions from a heavy-duty diesel engine over the transient test mode in Japan (JE05) were reduced by the plasma-assisted SCR system. However, unregulated emissions, e.g., aldehydes, were increased with the plasma environment. This paper reports the advantages and disadvantages of the plasma-assisted SCR system for a heavy-duty diesel engine.

Diesel engine has a good fuel economy and high durability and used widely for power source such as heavy duty in the world. On the other hand, it is required to reduce NOx (Nitrogen Oxides) and PM (Particulate Matter) emissions further from diesel exhaust gases to preserve atmosphere. The urea-SCR (Selective Catalytic Reduction) system is the most promising measures to reduce NOx emissions. DPF (Diesel Particulate Filter) system is commercialized for PM reduction. However, in case that a vehicle has a slow speed as an urban area driving, a diesel exhaust temperature is too low to activate SCR catalyst for NOx reduction in diesel emissions. Moreover, the diesel exhaust temperature becomes lower as a future engine has less fuel consumption. The purpose of this study is reduction of NOx emission from a heavy-duty diesel engine using the Urea SCR system at the low temperature.

EPA 2010 emissions regulations - currently the strictest standards in the world - place particular emphasis on exhaust gas thermal control technology. The Burner System, a device developed to control exhaust gas temperatures, is the most effective means of raising exhaust gas temperature, as this system can function under any engine conditions, including low engine speed and torque. The Burner System begins operating immediately when the engine is started, activating the Diesel Exhaust Fluid (DEF) - Selective Catalytic Reduction (SCR) System immediately, because the Burner System is active, it enables the diesel particulate filter active regeneration under any engine operating conditions as well. This technical paper reports Burner System (ActiveClean™ Thermal Regenerator) development results.

Hino Motors, Ltd. (Hino) launched the world's first hybrid city bus in 1991. Since then, the same hybrid technology has been refined and applied to a range of commercial vehicles, from city and tour buses to light and medium duty trucks, expanding the commercial hybrid vehicle line up. After 20 years of refining this technology, in 2011 Hino launched an all new light duty hybrid truck in Japan. An alternate version of the truck was developed to meet the particular needs of the North American market, differing from the Japanese model in several important features. The Japanese model's automated manual transmission was replaced with a fully automatic transmission, and the motor and inverter specifications were altered. This paper outlines the development process and introduces various characteristics of the technologies employed in the North American hybrid model.

More stringent emissions regulations, fuel economy standards, and regulations are currently being discussed to help reduce both CO2 and exhaust emissions. Vehicle manufacturers have been developing new engine technologies, such as downsizing and down-speeding with reduced friction loss, improved engine combustion and efficiency, heat loss recycling, power-train friction loss recycling, and reduced power-train friction loss. The use of more efficient fuel economy 5W-30 engine oils for heavy duty commercial vehicles has started to expand since 2009 in Japan as one technological solution to help reduce CO2 emissions. However, fuel economy 5W-30 oils for use in heavy duty vehicles in Europe are mainly based on synthetic oils, which are much expensive than the mineral oils that are predominantly used in Japan.

Diesel particulate trap systems are one of the effective means for the control of particulate emission from diesel vehicles. Hino has been researching and developing various diesel particulate trap systems for city buses. This paper describes two of the systems. One uses a wall flow filter equipped with an electric heater and a sensing device for particulate loading for the purpose of filter regeneration. Another makes use of a special filter named “Cross Flow Filter” with an epoch-making regeneration method called “Reverse Jet Cleaning”, by which it becomes possible to separate the part for particulate burning from the filter. Both systems roughly have come to satisfy the functions of trap systems for city buses, but their durability and reliability for city buses are not yet sufficient.

The sensitivity of steering increases as the vehicle speed rises. It requires a driver to make different steering maneuvers at high speed zone from that at low speed zone. In order to reduce the difference and to have a better steering “feel” for the driver, the characteristics of steering should be studied from both “the vehicle lateral movement corresponding to steering effort” and “the time lag of the vehicle lateral movement to steering effort”. And both should be decreased as vehicle speed rises. This paper explains how the above conclusion was reached through the development of engine/vehicle speed sensing power steering for commercial vehicles.

Urea selective catalyst reduction (SCR) systems have a high NOx conversion rate because the ammonia formed by the hydrolyzing urea solution reacts with NOx efficiently as a reducing agent. Systems combining urea-SCR and a diesel particulate filter (DPF) have been adopted in heavy duty vehicles to meet the post new long term emissions regulations in Japan. This study examined the emissions reduction performance of these systems after 160,000 km. The emissions that were examined included both regulated emissions (NOx, PM, HC, and CO) and unregulated emissions. As a result, the cleanness of diesel emissions from a urea-SCR and DPF system was confirmed.

When the engine oil evaporates in the crankcase, it is necessary to discharge to the outside of the engine or returns to the intake air as part of blow-by gas. The amount of oil content in the blow-by gas is preferable to be as small as possible. This paper researched the evaporation characteristics of diesel engine oil for heavy duty into blow-by gas using 5W-30 and 10W-30 engine oils with the equivalent to Noack. As a result, it is found that evaporate phenomenon cannot be explained well enough by just Noack and clarified of the oil evaporation mechanism in blow-by gas.

A new model of 4 × 2 semi-trailer tractor was introduced to the Japanese truck market from HINO MOTORS last year, which has improved riding comfort and remarkable features for trailer connecting/disconnecting operations. This new model has two typical methods of comfortable ride, those are full-floating cab mount system and air ride suspension for the rear axle. Since the analysis of tractor vibrations and the vehicle height control system of this model have given satisfactory results, and their outline is described here.