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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.

It has been proposed that downspeeding combined with high boost levels would effectively reduce fuel consumption in heavy-duty diesel engines. Under low-speed and high-boost operating conditions, however, the in-cylinder gas pressure, which acts on the piston crown, is greater than the piston inertia force (such that there is no force reversal), over the entire range of crank angles. Therefore, the piston pin never lifts away from the main loading area (the bottom) of the connecting rod small-end bushing where the contact pressure against the piston pin is highest. In such operating conditions, lubricant starvation is easily induced at the interface between the piston pin and small-end bushing. Through carefully devised engine tests, the authors confirmed that the piston pin scuffing phenomenon arises when the boost pressure exceeds a critical value at which the no-force reversal condition appears.

A diesel engine is advantageous in its high thermal efficiency, however it still wastes about 50% of total input energy to exhaust and cooling losses. A feasibility study of thermoacoustic refrigerator was carried out as one of the means to recuperate waste heat. The thermoacoustic refrigerator prototyped for this study showed a capability to achieve cooling temperature lower than -20 degree C, which indicated that the system has a potential to be used in refrigerator trucks not only for cargo compartment cooling but also for cabin cooling.

In order to improve the brake thermal efficiency of the engine, such as cooling and friction losses from the theoretical thermal efficiency, it is necessary to minimize various losses. However, it is also essential to consider improvements in theoretical thermal efficiency along with the reduction of the various losses. In an effort to improve the brake thermal efficiency of heavy-duty diesel engines used in commercial vehicles, this research focused on two important factors leading to the engine's theoretical thermal efficiency: the compression ratio and the specific heat ratio. Based on the results of theoretical thermodynamic cycle analyses for the effects of the above two factors, it was predicted that raising the compression ratio from a base engine specification of 17 to 26, and increasing the specific heat ratio would lead to a significant increase in theoretical thermal efficiency.

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.

An energy management method and model for small electric buses was studied. The model consists of a drive motor & inverter, a lithium ion battery, electric auxiliary devices and a mechanical powertrain. A small electric bus was developed based on the short travel distance, high charging frequency concept. Since 2012, two buses have operated as community buses in two different regions, and another bus started operations in a third region in 2013. The development of an energy management model accounting for operating conditions made it possible to keep the lithium ion battery capacity to a minimum. This paper describes energy management for this small electric bus, the design of the vehicle and the results of evaluating actual operation.

For the purpose of reducing fuel consumption, a hybrid heavy duty truck was considered. Generally, HV (Hybrid Vehicle)'s energy is regenerated from deceleration energy in urban area. Hybrid heavy duty truck's energy is regenerated from potential energy on highway. Under this circumstance, some portion of energy may not be accumulated, because capacity of HV battery is limited. In order to maximize accumulating energy in the next descent, HV battery's energy shall be adequately reduced beforehand. This can be achieved by optimizing motor assist torque considering road's altitude and gradient. In this paper, performance of the algorithm is discussed.

Reducing friction between the piston ring and cylinder is an effective way of meeting the demand for lower fuel consumption in vehicle engines. To that effect, the authors have proposed a new and efficient friction reduction treatment for the cylinder. At first glance, this treatment seems similar to typical microtexture treatments, but it is built on a different approach. Through a rig tester, it was confirmed that optimizing the shape of the dimples and the treatment area for the cylinder improves FMEP between the piston ring and the cylinder liner by 17%. This report presents an analysis of the test results to explain the mechanism by which this effect is achieved. Fuel consumption was measured in an actual engine, and a maximum fuel consumption improvement of 3.2% was confirmed after conversion to the Japanese heavy duty vehicle fuel economy standards (Category T2). Lubricating oil consumption, blow-by and durability were also examined.

In heavy duty (HD) trucks cruising on expressway, about 60% of input fuel energy is wasted as losses. So it is important to recover them to improve fuel economy of them. As a waste heat recovery system, a Rankine cycle generating system was selected. And this paper mainly reports it. In this study, engine coolant was determined as main heat source, which collected energies of an engine cooling, an EGR gas and an exhaust gas, for collecting stable energy as much as possible. And the exergy of heat source was raised by increase coolant temperature to 105 deg C. As for improving the system efficiency, saturation temperature difference was expanded by improving performance of heat exchanger and by using high pressure turbine. And a recuperator which exchanges heat in working fluid between expander outlet and evaporator inlet was installed to recover the heat of working fluid at turbine generator. Then a working fluid pump was improved to reduce power consumption of the system.

Design work for truck suspension systems requires multi-objective optimization using a large number of parameters that cannot be solved in a simple way. This paper proposes a process-based systematization concept for ride comfort design using a set-based design method. A truck was modeled with a minimum of 13 degrees of freedom, and suspension performance under various vehicle speeds, road surface conditions, and load amounts was calculated. The range of design parameters for the suspension, the range of performance requirements, and the optimal values within these ranges were defined based on the knowledge and know-how of experienced design engineers. The final design of the suspension was installed in a prototype truck and evaluated. The performance of the truck satisfied all the objectives and the effectiveness of the set-based design approach was confirmed.

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.

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.

This paper investigates the effects of Fischer-Tropsch Diesel (FTD) (a completely a paraffinic fuel) on the fuel supply system in automotive applications. In particular, the effects of Gas to Liquid (GTL) (an FTD synthesized from natural gas) on the elastomer components has been investigated by laboratory scale tests and field trials. In the field trials, GTL was supplied to a commercial vehicle operator and the effect of real running conditions was observed. Also, the laboratory scale testing to simulate the actual condition of usage of a commercial vehicle was conducted under stringent conditions, and a correlation with the field trials was investigated. As a result, no negative effects related to GTL were found.

Technical impacts on engine oil performance by the use of waste cooking oil as bio-diesel fuel (BDF) are not well understood while the industry has made significant progress in studies on quality specifications and infrastructure. The authors, who consist of a consortium organized by Japan Lubricating Oil Society (JALOS), examined technical effects of waste cooking oil as BDF on engine oil performance such as wear and high temperature corrosion using vehicle fleets and bench tests to identify technical issues of engine oil meeting the use of BDF. The study brings fundamental information about technical impacts of BDF on engine oils.

The U.S. Environmental Protection Agency (EPA) issued new emissions regulations, which came into effect in January, 2010. These EPA 2010 regulations are the most stringent emissions standards in the world, reducing both particulate matter (PM) and nitrogen oxides (NOx) to nearly zero levels. Hino Motors improved upon its previous EPA 2007-compliant engine, developing a new exhaust after-treatment system in which a Diesel Particulate active Reduction System (DPR), a Urea-Selective Catalytic Reduction (SCR) System and a Burner System are employed to meet EPA 2010 emissions regulations for medium duty commercial vehicles. DPR was already developed and utilized to reduce PM to meet EPA 2007 standards, but the Urea-SCR System is newly developed technology used to reduce NOx emissions to comply with EPA2010 emissions regulations. In addition, a Burner System is used to elevate exhaust gas temperatures in order to improve both SCR performance and DPR active Regeneration.

The new Diesel Particulate active Reduction (DPR) system was developed for a medium-duty commercial vehicle as a deNOx catalyst combined with the conventional DPR system to achieve the Japan Post New-Long-Term (JPNLT) emissions regulations. It consists of a catalyst converter named as the new DPR cleaner, a fuel dosing injector, NOx sensors, temperatures and pressure sensors. The new DPR cleaner was constructed from a Front Diesel Oxidation Catalyst (F-DOC), a catalyzed particulate Filter (Filter), and a Rear Diesel Oxidation Catalyst (R-DOC). A newly developed Hydrocarbon Selective Catalyst Reduction (HC-SCR) catalyst was employed for each catalyst aiming to reduce NOx emissions with diesel fuel supplied from the fuel dosing injector. While the total volume of the catalyst was increased, the compact and easy-to-install catalyst converter was realized through the optimization of the flow vector and flow distribution in it by means of Computational Fluid Dynamics (CFD) analysis.

In Biodiesel Fuel Research Working Group(WG) of Japan Auto-Oil Program(JATOP), some impacts of high biodiesel blends have been investigated from the viewpoints of fuel properties, stability, emissions, exhaust aftertreatment systems, cold driveability, mixing in engine oils, durability/reliability and so on. In the impact on exhaust emissions, the impact of high biodiesel blends into diesel fuel on diesel emissions was evaluated. The wide variety of biodiesel blendstock, which included not only some kinds of fatty acid methyl esters(FAME) but also hydrofined biodiesel(HBD) and Fischer-Tropsch diesel fuel(FTD), were selected to evaluate. The main blend level evaluated was 5, 10 and 20% and the higher blend level over 20% was also evaluated in some tests. The main advanced technologies for exhaust aftertreatment systems were diesel particulate filter(DPF), Urea selective catalytic reduction (Urea-SCR) and the combination of DPF and NOx storage reduction catalyst(NSR).

The emissions reduction potential of neat GTL (Gas to Liquids: Fischer-Tropsch synthetic gas-oil derived from natural gas) fuels has been preliminarily evaluated by three different latest-generation diesel engines with different displacements. In addition, differences in combustion phenomena between the GTL fuels and baseline diesel fuel have been observed by means of a single cylinder engine with optical access. From these findings, one of the engines has been modified to improve both exhaust emissions and fuel consumption simultaneously, assuming the use of neat GTL fuels. The conversion efficiency of the NOx (oxides of nitrogen) reduction catalyst has also been improved.

Large truck accidents sometimes result in severe damages or give large disturbance of traffic and there are demands of improving vehicle safety characteristics. Main types of traffic accidents concerned are rear-end collision and single accident. As countermeasures for rear-end collisions, world-first collision mitigation brake for commercial vehicles; Pre-crash Safety System, was developed. If there is possibility of collision, warning to driver and brake control intervention is carried out in stepwise fashion and collision speed is decreased. To achieve higher effect in collision mitigation, it is necessary to activate warning or brake-force in earlier timing. Inter-vehicle or infrastructure-vehicle communication offer promising prospect. Tractor-trailer combinations show some instable behaviors. “Roll Stability Assist” and “Vehicle Stability Control” were developed to assist drivers to avoid the occurrence of these instable behaviors.

A 2-LEG NOx Storage-Reduction (NSR) catalyst system is one of potential after-treatment technology to meet stringent NOx and PM emissions standards as Post New Long Term (Japanese 2009 regulation) and US'10. Concerning NOx reduction using NSR catalyst, a secondary fuel injection is necessary to make fuel-rich exhaust condition during the NOx reduction, and causes its fuel penalty. Since fuel injected in the high-temperature (∼250 degrees Celsius) exhaust instantly reacts with oxygen in common diesel exhaust, the proportion of fuel consumption to reduce the NOx stored on NSR catalyst is relatively small. A 2-LEG NSR catalyst system has the decreasing exhaust flow mechanism during NOx reduction, and the potential to improve the NOx reduction and fuel penalty. Therefore, this paper studies the 2-LEG NSR catalyst system. The after-treatment system consists of NSR catalysts, a secondary fuel injection system, flow controlled valves and a Catalyzed Diesel Particulate Filter (CDPF).