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Hino has developed new J-series medium-duty diesel engines for trucks and buses. The new J-series comprises four, five and six-cylinder engines with the same cylinder bore and stroke and with both naturally aspirated and charge air cooled. Both output and torque have been enhanced along with fuel efficiency in an engine that is lighter and more compact than ever and reaches new heights of durability and reliability. J-series engine features a 4-valve system and OHC valve train design, which achieved an uniform combustion by a centered nozzle and combustion chamber design. This decreases the maximum combustion temperature and hence improved the NOx,smoke and PM emissions. And a reduced pumping loss results in improving the fuel consumption. J-series engines thus meet the Japanese 1994 emission regulations. Another feature is a fully electronically controlled common-rail fuel injection system, which is equipped in a specified engine of naturally aspirated 6 cylinder.

Environmental protection is now one of the most important social concerns in the world. In 1998, emission controls in the US required the reduction of NOx by 20% from the 1994 limit. Hino Motors has developed new J-series medium-duty diesel engines for trucks that meet the US 1998 emissions regulations. The engines comprise turbocharged and aftercooled 4- and 6-cylinder engines of the same cylinder bore and stroke. The engines feature a 4-valve system, OHC valve train design, centered nozzle arrangement, and an optimum combustion chamber design, which achieved uniform combustion. With these features, the maximum combustion temperature was decreased, and hence reduced the NOx, smoke, and PM emissions. A muffler integrated with a catalytic converter (catalytic muffler) was adopted to reduce PM emissions further. The engines with the catalytic muffler have successfully met the US 1998 emissions regulations.

The spark-assisted methanol engine has disadvantages like poor fuel economy especially at light load and low spark plug durability affected by combustion characteristics. Investigations of combustion characteristics of the spark ignition system and the autoignition system in the methanol engine and discharge characteristics of a spark plug are described in this paper. It is clear that effective autoignition was accomplished by increasing the compression ratio and adopting an EGR system in the spark-assisted methanol engine. This new improved methanol engine which is named HAMS achieved good fuel economy at light load, a low NOx emission and longer spark plug life. And a heat insulated piston with a stainless steel cap is being investigated for further improvement of autoignition combustion characteristics.

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.

Heavy duty vehicles take a large role in providing global logistics. It is required to have both high durability and reduced CO2 from the viewpoint of global environment conservation. Therefore lubricating oils for transmission and axle/differential gear box are required to have excellent protection and longer drain intervals. However, it is also necessary that the gear oil maintain suitable friction performance for the synchronizers of the transmission. Even with such good performance, both transmission and axle/differential gear box lubricants must balance cost and performance, in particular in the Asian market. The development of gear oil additives for high reliability gear oil must consider the available base oils in various regions as the additive is a global product. In many cases general long drain gear oils for heavy duty vehicles use the group III or IV base oils, but it is desirable to use the group I/II base oils in terms of cost and availability.

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.

A new combustion system for a light duty D.I. diesel engine was developed, and a 3.5 ton payload truck (6.5 ton G.V.W.) equipped with this D.I. diesel engine and this combustion system realized good fuel economy and lower exhaust gas emission. Generally, light duty vehicles have to operate over a wide engine speed range. Therefore application of a D.I. diesel engine to light duty vehicles is difficult because of combustion tuning requirements over a wide engine speed range. Up to now, most of the diesel engines for light vehicles have been of the I.D.I. type. But the D.I. diesel engine has an evident advantage of lower fuel consumption. In these circumstances the authors developed a new combustion chamber shape for a small D.I. diesel engine with turbulence induced intake port and optimum fuel injection equipment. Various combustion chamber geometries were tested and evaluated.

The objective of this study was to develop a test method for heavy-duty HEVs using a hardware-in-the-loop simulator (HILS) to enhance the type-approval-test method. To achieve our objective, HILS systems for series and parallel HEVs were actually constructed to verify calculation accuracy. Comparison of calculated and measured data (vehicle speed, motor/generator power, rechargeable energy storage system power/voltage/current/state of charge, and fuel economy) revealed them to be in good agreement. Calculation error for fuel economy was less than 2%.

This paper presents technical solutions and a development process to accomplish not only superior fuel economy but also excellent driveability with a turbocharged diesel engine for heavy duty trucks. For better fuel economy, one of the basic considerations is how to decrease the friction losses of the engine itself while keeping the required horsepower and torque characteristics. A high boost turbocharged small engine offers this possibility, but it has serious disadvantages such as inferior low speed torque, poorer accelerating response, insufficient engine braking performance, and finally not always so good fuel consumption in the engine operating range away from the matching point between engine and turbocharger. These are not acceptable in complicated traffic conditions like those in Japan - a mixture of mountainous and hilly roads, city road with numerous traffic signals, and freeways.

The purpose of the investigation presented here was to develop a high quality SAE 10W-30 engine lubricating oil to meet the heavy duty operating conditions of trucks. The operation of their engines is predicted to become more severe in future because of the trend toward higher power output, nore severe regulation of exhaust emissions and noise as well as the increasing demand for better fuel economy. To meet these demands, an improvement of the wear resistance of engine lubricating oil was considered to be the most important aspect for the development of high performance diesel engines in the future. The engine test developed was able to evaluate various experimental oils by observing wear resistance of the valve train which is considered to be one of the most severe tri-bological conditions. The best oils were determined by optimum selection of the amount and type of detergent, ashless dispersant and zinc dithiophosphate.

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.

A new combustion system for a light duty D. I. diesel engine was developed and introduced (1)*. The combustion chamber, which was used in the combustion system, has 4 concaves on the periphery of the inner wall and was calld HMMS-III. This combustion chamber realized better fuel consumption and lower smoke level over a wide speed range. However, the effects of HMMS-III combustion chamber on in-cylinder air motion and combustion characteristics were not yet clarified in the previous paper. In this study, in order to clarify the effects of HMMS-III combustion chamber on in-cylinder air motion and characteristics, analysis of flow direction and streak line via oil film method was carried out in comparison with flat dish and re-entrant type combustion chambers. Further, measurement of in-cylinder air motion by L.D.V. and observation of mixture formation and burning process via high speed schlieren photography were carried out.

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.

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.

For the 1990's diesel engines, particulate control has been an important problem. The purpose of this paper is to discuss emission control needs for heavy duty diesel truck engines for the 1990's. This paper will focus on the factors such as fuel injection pressure and fuel properties which most affect particulate emission. The characteristics of diesel spray in the atmosphere and also actual combustion of a turbocharged and charge-cooled H.D. D.I diesel engine were studied as a function of injection pressure ranging from 50 to 150 MPa. Experimental results show that high pressure injection improves the atomization and air entrainment. Though Bosch smoke level, fuel consumption and combustion period decreased with the rise of injection pressure, particulate emission in EPA transient test cycle did not decrease dut to an increase of SOF.

This paper describes the experimental studies of turbocharged and intercooled diesel engines with particular emphasis on combustion characteristics following increase of boost pressure. Through these studies, it has become possible to determine the optimum air quantity for minimizing fuel consumption at each engine speed range under the restrictive conditions of NOx emission, exhaust smoke and maximum cylinder pressure. Discussed also is the lack of air quantity in the low engine speed range of high-boost turbocharged diesel engines. Various turbocharging systems to improve air quantity in this speed range are introduced herein. Practically the engine performance of conventional turbocharging, waste gate control turbocharging and variable geometry turbocharging are discussed from the viewpoint of torque recovery in the low engine speed range.

Hino Motors had developed an electronically controlled mechanical automatic transmission and employed it for the ′85 models of large size buses, and also ′86 models of heavy/ medium duty trucks. This system gives minimum fuel consumption and even smoother/easier driving than an automatic transmission with torque converter, by controlling an engine also with a transmission and employing an oil spray clutch. The trade name of this system is EE-Drive which means easy and economy drive.

1 To meet the Japan Post New-Long-Term (Japan 2009) emissions regulation introduced in 2009, The Hydrocarbon Selective Catalytic Reduction (HC-SCR) system for the NOx emission with a diesel fuel was chosen among various deNOx after-treatment systems (the Urea-SCR, the NOx storage-Reduction Catalyst and so on). The HC-SCR was adopted, in addition to combustion modification of diesel engine (mainly cooled EGR) as the New DPR system. The New DPR system for medium and light duty vehicles was developed as a world's first technology by Hino Motors. Advantages of the New DPR are compact to easy-to-install catalyst converter and no urea solution (DEF) injection (regardless urea infrastructure) as compared the Urea-SCR system.

The objective of this study is to improve fuel economy and reduce carbon dioxide emissions in diesel-electric hybrid automotive powertrains by developing an exhaust gas turbine generator system which utilizes exhaust gas energy from the turbocharger waste gate. The design of the exhaust gas turbine generator was based on a conventional turbocharger for a direct-injection diesel engine. Data from steady-state bench tests using air indicates about 50% of the turbine input energy can be converted to electric energy. Turbine generator output averaged 3 kW, while a maximum of about 6 kW was observed. Based on this data, we estimate that energy consumption in a vehicle could be reduced between 5% and 10%. Engine tests were conducted under both steady-state and transient conditions. These tests revealed that optimal performance occurred under high-speed, high-load conditions, typical of highway or uphill driving, and that performance at low-speed, low-loads was relatively poor.

To investigate the future direction of diesel emission control technologies and fuel technologies, exhaust emissions tests of diesel vehicles/engines with advanced after-treatments such as NSR catalyst, CR-DPF, and Urea-SCR or a combination of these, were conducted using various fuels, and fuel sulfur effect on performance of the after-treatments after mileage accumulation was also evaluated in step II study of JCAP Diesel WG. Overall results shows that the after-treatments have significant effects on reducing emission and reducing fuel sulfur have significant effects on function of the after-treatments in term of decrease of sulfate and SOF, and less deterioration of function of after-treatments after mileage accumulation.