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Technical Paper

Development of an Electric Concept Vehicle with a Super Quick Charging System

Recent environmental concerns such as atmospheric pollution and energy conservation have intensified the need to develop pollution-free, energy-efficient vehicles. One such solution is the electric automobile which draws its power from rechargeable batteries. There are few vehicles on the road today because present batteries can store very little energy compared with that of a tank of gasoline. To obtain adequate range, this concept vehicle adopts a new battery which can be recharged to 40% of capacity in six minutes. This super quick charging system makes it possible to recharge the batteries at an electric recharging station just as gasoline-powered vehicles are refilled at service stations. The electric concept vehicle also has improved aerodynamics, reduced rolling resistance and a lighter curb weight, which help to assure adequate range.
Technical Paper

Study of the Generation mechanism for Abnormal Exhaust Noise

Based on experimental analysis, the generation mechanism of abnormal exhaust noise which is characterized by an intermittent high frequency aetallic sound, is clarified by bench testing of a FWD vehicle. The noise is caused by large amplitude pressure waves (finite amplitude waves) in the exhaust pipe. They are amplified due to interference between reflected waves and subsequent waves from the engine, and are finally transformed into shock waves in the propagation process along the exhaust pipe, resulting in abnormal exhaust noise. By theoretical analysis of finite amplitude waves, the wave profile in the propagation process and the transition distance to the shock wave can be solved analytically where the assumptions of mass, momentum, and energy conservation are valid, until the moment of shock wave formation. The transition distance is a key parameter in analyzing the growth and existence of shock waves.
Technical Paper

Development of a Compact 3-Liter V6 Nissan Engine

This paper presents a compact 3-liter DOHC V6 engine that has been newly designed for the Nissan Maxima. The aims set for the development of this new engine were to achieve a compact package and excellent fuel efficiency. The engine is built around a 4-valve-per-cylinder configuration with a high compression ratio and incorporates a variable valve timing control system, aerodynamic intake ports and roller rocker arms. These features enable it to provide good fuel economy while delivering excellent acceleration. The compact package has been achieved by adopting a 2-stage cam drive, narrow angle valve geometry and an optimized arrangement for the endpivot type hydraulic lash adjusters.
Technical Paper

Performance and Exhaust Emissions of Nissan FFV NX Coupe

The FFVs under study operates on either M85 or M0 or any mixture of the two. Nissan has been actively conducting reseach and development on flexible fuel vehicles (FFVs) to explore the possibilities for long-range energy conservation and air quality improvement. The engine converted for use in these FFVs is a 1.6 liter, four-cylinder in-line powerplant, with dual overhead camshafts and four valves per cylinder. It employs the Nissan Variable valve timing Control System (NVCS). The fuel sensor for measuring the methanol concentration in the fuel has been improved both in terms of accuracy and durability. This paper describes the engine performance and exhaust emission levels (formaldehydes unburned methanol and HC emissions) obtained with both M85 and M0.
Technical Paper

Swirling Flow Type Jet Pump for Transferring Fuel Inside Saddle-Shaped Fuel Tanks

This paper presents a swiring flow type jet pump which has been developed and in put into practical use in transferring fuel between sumps in saddle-shaped fuel tanks. The pump is driven by the force of excess fuel returning from the engine. The major structural features of the pump are described along with its performance. Various problems encountered in the process of developing the pump are discussed along with the technologies developed to resolve them. Particular attention is focused on the effects that the geometries if the nozzle, throat and swirling groove have on fuel transfer efficiency. The results of experiments carried out to analyze these correlations are also presented.
Technical Paper

The New Nissan 1.7 Liter 4 Cylinder Diesel Engine

The new Nissan 1.7 liter 4 cylinder diesel engine has been developed to meet the social requirements for energy conservation. The main objective was to improve fuel economy without sacrificing driveability, and this has been achieved by minimizing engine weight, reducing mechanical friction loss and optimizing the combustion system. The CA series gasoline engine, which is known for its light weight, was chosen as the base engine for dieselization. The swirl chamber combustion system used for the LD28 engine was modified to satisfy the requirements for high power, good fuel economy and low noise. Engine noise has been reduced with the aid of several analytical methods such as laser holography. Special attention has been paid to the reduction of diesel knock which is most offensive to the ear. To install this engine in a small FWD vehicle transversely, much effort went into the minimizing of the engine length and width.
Technical Paper

Development of an On-Board Fuel Reforming Catalyst for a Gasoline Engine

On-board hydrogen generation technology using a fuel reforming catalyst is an effective way to improve the fuel efficiency of automotive internal combustion engines. The main issue to be addressed in developing such a catalyst is to suppress catalyst deterioration caused by carbon deposition on the catalyst surface due to sulfur adsorption. Enhancing the hydrocarbon and water activation capabilities of the catalyst is important in improving catalyst durability. It was found that the use of a rare earth element is effective in improving the water activation capability of the catalyst. Controlling the hydrocarbon activation capability of the catalyst for a good balance with water activation was also found to be effective in improving catalyst durability.
Technical Paper

Development of GF-5 0W-20 Fuel-Saving Engine Oil for DLC-Coated Valve Lifters

A suitable GF-5 engine oil formulation is investigated to improve the fuel economy of gasoline engines with hydrogen-free DLC-coated valve lifters. Molybdenum dithocarbamate (MoDTC) is shown to be a suitable friction modifier for low viscosity grade engine oils like 0W-20. A suitable Ca salicylate detergent is also determined from several types examined for maximizing the friction reduction effects of MoDTC. The most suitable Ca salicylate has a chemical structure capable of forming a borophosphate glass film on metal surfaces, which is known to improve the effects of MoDTC. A high viscosity index Group III base oil (VI>140) is also effective in improving fuel efficiency. It is further clarified that the structural design of the polymethacrylate viscosity modifier is another important factor in reducing engine friction.
Technical Paper

Functional Design of a Motor Integrated CVT for a Parallel HEV

We succeeded in developing a parallel hybrid electric vehicle (HEV) with a fuel efficiency in the 10-15 mode more than double that of existing vehicles of the same class of driving performance. A prominent feature of this HEV system is the belt-drive continuously variable transmission (CVT) with built-in traction motor and powder clutch. Adopting a more efficient configuration proved effective in minimizing cost increases and loss of space utility and offered the same reliability provided by existing vehicles. This paper discusses the functional design aspects of the parallel HEV system, which holds great promise for viable mass production.
Technical Paper

Anti-Shudder Property of Automatic Transmission Fluids - A Study by the International Lubricants Standardization and Approval Committee (ILSAC) ATF Subcommittee

In recent years, the slip lock-up mechanism has been adopted widely, because of its fuel efficiency and its ability to improve NVH. This necessitates that the automatic transmission fluid (ATF) used in automatic transmissions with slip lock-up clutches requires anti-shudder performance characteristics. The test methods used to evaluate the anti-shudder performance of an ATF can be classified roughly into two types. One is specified to measure whether a μ-V slope of the ATF is positive or negative, the other is the evaluation of the shudder occurrence in the practical vehicle. The former are μ-V property tests from MERCON® V, ATF+4®, and JASO M349-98, the latter is the vehicle test from DEXRON®-III. Additionally, in the evaluation of the μ-V property, there are two tests using the modified SAE No.2 friction machine and the modified low velocity friction apparatus (LVFA).
Journal Article

Analysis of Oil Film Generation on the Main Journal Bearing Using a Thin-Film Sensor and Elasto-Hydrodynamic Lubrication (EHL) Model

Reducing friction in the crankshaft main bearings is an effective means of improving the fuel efficiency of reciprocating internal combustion engines. To realize these improvements, it is necessary to understand the lubricating conditions, in particular the oil film pressure distributions between crankshaft and bearings. In this study, we developed a thin-film pressure sensor and applied it to the measurement of engine main bearing oil film pressure in a 4-cylinder, 2.5 L gasoline engine. This thin-film sensor is applied directly to the bearing surface by sputtering, allowing for measurement of oil film pressure without changing the shape and rigidity of the bearing. Moreover, the sensor material and shape were optimized to minimize influence from strain and temperature on the oil film pressure measurement. Measurements were performed at the No. 2 and 5 main bearings.
Journal Article

Advanced Technology for Dry Multi-Plate Clutch in FWD HEV Transmission (JATCO CVT8 HYBRID)

There has been a growing need in recent years to further improve vehicle fuel efficiency and reduce CO2 emissions. JATCO began mass production of a transmission for rear-wheel-drive (RWD) hybrid vehicle with Nissan in 2010, which was followed by the development of a front-wheel-drive (FWD) hybrid system (JATCO CVT8 HYBRID) for use on a midsize SUV in the U.S. market. While various types of hybrid systems have been proposed, the FWD system adopts a one-motor two-clutch parallel hybrid topology which is also used on the RWD hybrid. This high-efficiency system incorporates a clutch for decoupling the transmission of power between the engine and the motor. The hybrid system was substantially downsized from that used on the RWD vehicle in order to mount it on the FWD vehicle. This paper describes various seal technologies developed for housing the dry multi-plate clutch inside the motor, which was a key packaging technology for achieving the FWD hybrid system.
Journal Article

Development of Low Viscosity API SN 0W-16 Fuel-Saving Engine Oil Considering Chain Wear Performance

A low viscosity API SN 0W-16 engine oil was developed to achieve a 0.5% improvement in fuel efficiency over the current GF-5/API SN 0W-20 oil. Oil consumption and engine wear are the main roadblocks to the development of low viscosity engine oils. However, optimization of the base oil and additives successfully prevent oil consumption and wear. First, it was confirmed in engine tests that NOACK volatility is still an effective indicator of oil consumption even for a low viscosity grade like 0W-16. As a result of base oil volatility control, the newly developed oil achieves the same level of oil consumption as the current GF-5/API SN 0W-20 oil. Second, it was found that the base oil viscosity and molybdenum dithiocarbamate (MoDTC) had a significant effect on chain wear in rig testing that simulated silent chain wear. For the same base oil viscosity, the new oil maintains the same oil film thickness under high surface pressure.
Technical Paper

Development of a New 2L Gasoline VC-Turbo Engine with the World’s First Variable Compression Ratio Technology

A new 2L gasoline turbo engine, named KR20DDET was developed with the world’s first mass-producible variable compression turbo (VC-Turbo) technology using a multi-link variable compression ratio (VCR) mechanism. It is well known that increasing the compression ratio improves gasoline engine thermal efficiency. However, there has always been a compromise for engine designers because of the trade-off between increasing the compression ratio and knocking. At Nissan we have been working on VCR technology for more than 20 years and have now successfully applied this technology to a mass production engine. This technology uses a multi-link mechanism to change the top and bottom dead center positions, thereby allowing the compression ratio to be continuously changed. The VC-Turbo engine with this technology can vary the compression ratio from 14:1 for obtaining high thermal efficiency to 8:1 for delivering high torque by taking advantage of the strong synergy with turbocharging.
Journal Article

Connected Vehicle Accelerates Green Driving

After the turn of the century, growing social attention has been paid to environmental concerns, especially the reduction of greenhouse gas emissions and it comes down to a personal daily life concern which will affect the purchasing decision of vehicles in the future. Among all the sources of greenhouse gas emissions, the transportation industry is the primary target of reduction and almost every automotive company pours unprecedented amounts of money to reengineer the vehicle technologies for better fuel efficiency and reduced CO2 emission. Besides those efforts paid for sheer improvements of genuine vehicle technologies, NISSAN testified that “connectivity” with outside servers contributed a lot to reduce fuel consumption, thus the less emission of GHG, with two major factors; 1. detouring the traffic congestions with the support of probe-based real-time traffic information and 2. providing Eco-driving advices for the better driving behavior to prompt the better usage of energy.