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Many papers have mentioned, in passing, a phenomena that is known as “airtightness”, which is one factor that hinders automobile doors from closing. It also causes the eardrums of any passengers in the vehicle to be temporarily pressurized when the door is closed. However, few documents have considered this phenomena in detail. In this paper, we investigate the magnitude of “airtightness” as it affects ear pressure and examine its relationship to such factors as the volume of the passenger compartment, door's opening area and its inertial moment. Finally, we utilized estimation methods to predict its influence on the force required to close the door and the amount of the resultant air draft.

In this paper, we have analyzed the problem of the engine noise propagation and have classified that there is a fundamental relationship between exterior noise and structural design. In the case of light vehicles, we have isolated the following 2 factors in structural design which have a direct bearing on exterior noise. (1) The layout and the area of exposed openings in the engine room. (2) The ability of the engine room to absorb noise. In conclusion we suggest comprehensive approach to the problem of automotive noise reduction.

A light weight,multifunctional plastic reinforcement has been developed for the outer body panels of vehicles. This new plastic reinforcement,composed mainly of polyvinylchloride resin, epoxy resin and an organic foaming agent, provides a 63% weight reduction over conventional plastic reinforcements, while adding the damping function to outer body panels. This paper introduces the process followed in developing the new plastic reinforcement and describes its characteristics. This new plastic reinforcement is already employed in the Nissan S-Cargo model, and it will be adopted in other passenger car models to be released in the near future.

Research is under way on an engine system [1] that achieves a variable compression ratio using a multiple-link mechanism between the crankshaft and pistons for the dual purpose of improving fuel economy and power output. At present, there is no database that allows direct judgment of the feasibility of the specific sliding parts in this mechanism. In this paper, the feasibility was examined by making a comparison with the sliding characteristics and material properties of conventional engine parts, for which databases exist, and using evaluation parameters based on mixed elasto-hydrodynamic (EHD) lubrication calculations. In addition, the innovations made to the mixed EHD calculation method used in this study to facilitate calculations under various lubrication conditions are also explained, including the treatment of surface roughness, wear progress and stiffness around the bearings.

Maintaining reliability of the connecting rod bearing is a very important subject, and the following is a problem that needs to be overcome. Predicting reliability has generally depended on minimum oil film thickness (M.O.F.T), but recently, the engines of passenger cars which have greater power and speed potential than conventional ones are sometimes run beyond their M.O.F.T. limit (a degree of roughness around the crank shaft's axis.) In such a case, it is so difficult to predict reliability according to M.O.F.T., that we need a new index which directly shows seizure and wear. For this purpose, we found that the crank shaft pin temperature can be a key cause of seizure and wear according to an analysis of the relationship between its temperature and the seizure and wear caused intentionally. Using this method, we confirmed that the combination of bearing and crank shaft materials is very important for preventing seizure and wear.

There has been a growing need to develop more compact automatic transmissions with a greater number of speeds for better fuel economy and better driveability. This study investigated a method for determining suitable planetary gear trains for today's transmissions. A computer program has been developed for application to five-speed transmissions consisting of two planetary gearsets. By analyzing various gear train possibilities, the program can identify which gearsets are suitable for different conditions, including the number of speeds, the number of binding elements, topological suitability and other factors.

In the initial design stage, it is important to discuss what kind of body concept is effective from a viewpoint of environment burden reduction. This paper describes the importance of both weight reduction and recycling through conducting LCA (Life Cycle Assessment) for four kinds of body structures. In addition, using each software, DFMA (Design for Manufacture and Assembly), DFE (Design for Environment) and LCA to parts unit, each effectiveness was discussed through the assessment of the material-hybrid body.

It is important to understand the influence of housing stiffness on bearing performance, particularly for the connecting rod bearings of automotive engines. It is known that the engine lubricant shows a piezoviscous characteristic whereby its viscosity changes under the influence of pressure. Engine bearings under a heavy load are apt to be influenced in this way. In this study, the effects of connecting rod stiffness and lubricant piezoviscosity on bearing performance were examined by elastohydrodynamic lubrication (EHL) analysis under conditions corresponding to the high-speed operation of an actual engine. The results indicated that under such heavy load conditions housing stiffness greatly affects friction loss because of lubricant piezoviscosity. It was also found that the piezoviscosity of the lubricant has a large effect on bearing performance, as does its viscosity under atmospheric pressure.

The possibility of predicting engine bearing durability by elastohydrodynamic lubrication (EHL) calculations was investigated with the aim of being able to improve durability efficiently without conducting numerous confirmation tests. This study focused on the connecting rod big-end bearing of an automotive engine. The mechanisms of wear and fatigue, which determine bearing durability, were estimated by comparing the results of EHL analysis and experimental data. This comparison showed the possibility of predicting the wear amount and the occurrence of fatigue by calculation.

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.

This paper explains the specific measures taken to develop the body and underfloor of the newly developed Electric Vehicle for the purpose of reducing drag. Additionally, the headlamps and fenders were designed with innovative shapes to reduce wind noise that occurs near the outside mirrors. As a result of utilizing the aerodynamic advantages of an electric vehicle to maximum effect, The newly developed Electric Vehicle achieves a class-leading drag coefficient and interior quietness.

An electric vehicle (EV) has less powertrain energy loss than an internal combustion engine vehicle (ICE), so its aerodynamic accounts have a larger portion of drag contribution of the total energy loss. This means that EV aerodynamic performance has a larger impact on the all-electric range (AER). Therefore, the target set for the aerodynamics development for a new EV hatchback was to improving AER for the customer’s benefit. To achieve lower aerodynamic drag than the previous model’s good aerodynamic performance, an ideal airflow wake structure was initially defined for the new EV hatchback that has a flat underbody with no exhaust system. Several important parameters were specified and proper numerical values for the ideal airflow were defined for them. As a result, the new EV hatchback achieves a 4% reduction in drag coefficient (CD) from the previous model.

Car rust has been a big problem. To improve the effectiveness of rustproofing, car materials and some methods are being developed. Sealing the seams of body panels is one important method. But the sealing operation is a difficult process and it is not easy to maintain quality standards for workmen and automatized systems. To overcome this problem, we developed an automatic robot sealing system with following features: 1. The system can be easily installed on an existing conveyor and follows the line conveyor in synchronization during sealing operation. 2. Small robots can cover wide area inside the vihecle. 3. New sealant supply controllers can regurate the supply rate in response to speed and motion of robots with a high accuracy. This system has already been installed in the Murayma plant and has proved successful in achieving a high quality sealing result.

This paper deals with the development of plastics recycling technology, which is one key to resolving environmental and natural resource problems and encouraging recycling activities. Bumpers are among the heaviest plastic auto parts, so the technology for recycling bumpers is strongly required. Paint remaining on bumpers causes the strength of the recycled material to decline and degrades its surface quality. Therefore, unless the paint is removed, it is impossible to use recycled material to manufacture new bumpers. This hampers recycling efforts and results in low-value recycled material. Consequently, it is essential to develop a simple paint removing without chemical substances for practical plastics recycling at low cost. Two topics are discussed in this paper. The first concerns the mechanism of paint removal and the development of a technique for utilizing that mechanism.

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.

Use of high strength steel (HSS) could be an important consideration in achieving competitive weight and safety performance of the body-in-white (BIW). This study covers key technical issues in the application development. Many aspects were studied such as formability, weldability and impact strength for application of this grade to the BIW. One of the key issues is spot weldability, especially in the assembly of heavy gauge materials for structural parts. The spot weld strength appears not to satisfy the target for some HSS applications, when hardness of the nugget is high. The relation between weld strength and the chemical composition of steel sheets was studied, because hardness can be controlled by chemical composition and welding conditions. It was found that using lower carbon content or carbon equivalent compared to conventional grades could improve weld strength.

There are strong demands for vehicle weight reductions so as to improve fuel economy. At the same time, it is also necessary to ensure crash safety. One effective measure for accomplishing such both requirements conflicting each other is to apply advanced high strength steel (AHSS) of 780 MPa grade or higher to the vehicle body. On the other hand, higher strength steels generally tend to display lower elongation causing formability deterioration. Nissan Motor Corporation have jointly developed with steel manufacturers a new 980 MPa grade AHSS with high formability with the aim of substituting it for the currently used 590 MPa grade high-tensile steel. Several application technologies have been developed through the verifications such as formability, resistance spot weldability, crashworthiness, and delayed fracture.

The use of CAE software in developing plastic components has advanced rapidly in recent years. This progress has been supported by the development of practical analytical tools, based on the finite element and boundary element methods, and on the dramatic improvements seen in computer performance. Following the introduction of a flow analysis program in 1982, Nissan has developed and implemented advanced programs for use in developing plastic components and has integrated the programs into a unified in-house system. This system is being utilized at the design and manufacturing stages of interior and exterior trim parts and has produced concrete results in different phases of component development. Work is now proceeding on the development of a system that can simultaneously analyze both the component performance and the factors that need to be considered in the manufacturing process.

Evaluations of dummy injury readings obtained in regulatory crash tests and new car assessment program tests provide indices for the development of crash safety performance in the process of developing new vehicles. Based on these indices, vehicle body structures and occupant restraint systems are designed to meet the required occupant injury criteria. There are many types of regulatory tests and new car assessment program tests that are conducted to evaluate vehicle safety performance in side impacts. Factoring all of the multiple test configurations into the development of new vehicles requires advanced design capabilities based on a good understanding of the mechanisms producing dummy injury readings. In recent years, advances in computer-aided engineering (CAE) tools and computer processing power have made it possible to run simulations of occupant restraint systems such as side airbags and seatbelts.

Hydrofrorming is an efficient forming process to produce automotive parts for reducing weight of cars. In order to reduce the period of development of hydrofoming parts, numerical simulation using FEM is applied to evaluate formability. A pipe needs to be bent before hydroforming for forming complicated shape parts. A pipe bending process is also necessary to FEM simulation. In this paper, a highly effective method to create a bent pipe FEM model based on geometrical changing between a pipe before and after bending is proposed. The widely used draw bending process is supposed to be applied. The method can construct the model in a short time. Therefore total computation time can be reduced drastically. The effects of number of integration points and elements to the computed results and springback prediction after bending are also investigated. The proposed method are applied to a actual part, the computed results are in good agreement with the experimental results.