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Riding comfort on the seat is one of the important factors for vehicle comfort. To analyze riding comfort, there were some models for predicting human vibrations in the past studies. On the other hand, it is strongly affected by human body motion caused by vehicle excitation during driving especially low frequency, but it is difficult to predict human motion due to an unclear mechanism of muscle reflex. The purpose of this study is to construct virtual riding comfort testing simulation based on virtual prototyping of the seat. In this study, a virtual occupant model that predicts occupant motion on the seat against external excitation including muscle reflex for maintaining sitting posture constructed. The whole body was modeled as 15 segments biomechanical model (1D) with wobbling mass. Each joint has passive elastic torque and damping torque springs. Human body surface was modeled as rigid shape.

A flag is a global boolean variable used to achieve synchronization between various tasks of an embedded system. An application implementing flags performs actions or events based on the value of the flags. If flag variables are not implemented properly, certain synchronization related issues can arise which can lead to unexpected behavior or failure of the underlying system. In this paper, we present an automated verification technique to identify and verify flag usage patterns at an early stage of code development. We propose a two-step approach which consists of: a. identification of all potential flag variables and b. verification of flag usage patterns against predefined set of rules. The results of our experiment demonstrate that the proposed approach reduces the cost and complexity of the flag review process by almost 70%.

In order to significantly reduce NOx levels by EGR (Exhaust Gas Recirculation), while maintaining good fuel economy and driveability, the EGR flow rate must be properly and accurately controlled under a variety of engine operating conditions. Toward this objective, a new EGR control system was developed. It utilizes a carburetor venturi vacuum for a stable reference signal that represents the engine operating condition and it controls the EGR flow rate by using a feedback principle to obtain sufficient flexibility compatible with several different engines. Its control characteristics were mathematically analyzed. And it has also been confirmed that the system can automatically compensate for the drift in EGR characteristics. This EGR control system has been utilized in Nissan’s emission control systems in order to comply with the 1978 Japanese Emission Standards and the 1980 U.S. Federal and California Emission Standards.

This paper describes a variable magnetomotive force interior permanent magnet (IPM) machine for use as a traction motor on automobiles in order to reduce total energy consumption during duty cycles and cut costs by using Dy-free magnets. First, the principle of a variable magnetomotive force flux-intensifying IPM (VFI-IPM) machine is explained. A theoretical operating point analysis of the magnets using a simplified model with nonlinear B-H characteristics is presented and the results are confirmed by nonlinear finite element analysis. Four types of magnet layouts were investigated for the magnetic circuit design. It was found that a radial magnetization direction with a single magnet is suitable for the VFI-IPM machine. Magnetization controllability was investigated with respect to the magnet thickness, width and coercive force for the prototype design. The estimated variable motor speed and torque characteristics are presented.

Wireless Power Transfer (WPT) promises automated and highly efficient charging of electric and plug-in-hybrid vehicles. As commercial development proceeds forward, the technical challenges of efficiency, interoperability, interference and safety are a primary focus for this industry. The SAE Vehicle Wireless Power and Alignment Taskforce published the Recommended Practice J2954 to help harmonize the first phase of high-power WPT technology development. SAE J2954 uses a performance-based approach to standardizing WPT by specifying ground and vehicle assembly coils to be used in a test stand (per Z-class) to validate performance, interoperability and safety. The main goal of this SAE J2954 bench testing campaign was to prove interoperability between WPT systems utilizing different coil magnetic topologies. This type of testing had not been done before on such a scale with real automaker and supplier systems.

In order to clarify future automobile technologies and fuel qualities to improve air quality, second phase of Japan Clean Air Program (JCAPII) had been conducted from 2002 to 2007. Predicting improvement in air quality that might be attained by introducing new emission control technologies and determining fuel qualities required for the technologies is one of the main issues of this program. Unregulated material WG of JCAPII had studied unregulated emissions from gasoline and diesel engines. Eight gaseous hydrocarbons (HC), four Aldehydes and three polycyclic aromatic hydrocarbons (PAHs) were evaluated as unregulated emissions. Specifically, emissions of the following components were measured: 1,3-Butadiene, Benzene, Toluene, Xylene, Ethylbenzene, 1,3,5-Trimethyl-benzene, n-Hexane, Styrene as gaseous HCs, Formaldehyde, Acetaldehyde, Acrolein, Benzaldehyde as Aldehydes, and Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene as PAHs.

Combinations of swirl flow and tumble flow generated by 13 types of swirl control valve were tested by using both impulse steady flow rig and LDV. Comparison between the steady flow characteristics and the result of LDV measurement under motoring condition shows that tumble flow generates turbulence in combustion chamber more effectively than swirl flow does, and that swirling motion reduces the cycle by cycle variation of mean velocity in combustion chamber which tends to be generated by tumbling motion. Performance tests are also carried out under the condition of homogeneous charge. Tumble flow promotes the combustion speed more strongly than expected from its turbulence intensity measured by LDV. It is also shown that lean limit air fuel ratio does not have a strong relation with cycle variation of mean velocity but with turbulence intensity.

Flat panel displays for automobiles are facing a new era with the development of navigation systems. As navigation systems become more important as driver's assistance devices, development of birds-eye-view and 3D displays continues, as well as improvements for larger display screens and higher mounting positions. In response to the progress of mobile multimedia technologies, demands for larger display screens and larger aspect ratios have been increasing. Significance for improvements to anti-glare features or view angles has increased as they provide better visibility and the increase layout options. The use of human machine information interaction, which interfaces visual, audio and tactile senses, makes it possible to realize safer, more convenient and comfortable multimedia era vehicle

In the course of developing a low-emission manual transmission vehicle, coast surge in the fore-and-aft direction resulting from the installation of certain emission-control devices was sometimes experienced immediately after the initiation of vehicle deceleration. Our investigation revealed that this vehicle surge was caused by combustion irregularities in a sequence of combustion-misfire-intense combustion events occurring every several cycles. A new combustibility standard. Gt/Feff, defined as the ratio of total cylinder mixture weight Gt to effective fuel weight Feff, was found to predict combustibility and irregular combustion over the entire mixture range. As a result, driveability during deceleration was improved by modifying key emission-control components.

Three-dimensional computation has been applied to analyze combustion and emission characteristics in direct-injection diesel engines. A computational code called TurboKIVA was used to investigate the effects of the swirl ratio, one of the fundamental factors related to combustion control, on combustion characteristics and NOx and soot emissions. The code was first modified to calculate soot formation and oxidation and the precise behavior of fuel drops on the combustion chamber wall. As a result of improving calculation accuracy, good agreement was obtained between the measured and predicted pressure, heat release rate and NOx and soot emissions. Using this modified version of TurboKIVA, the effects of the swirl ratio on NOx and soot emissions were investigated. The computational results showed that soot emissions were reduced with a higher swirl ratio. However, a further increase in the swirl ratio produced greater soot emissions.

Nissan’s new 2.8 liter in-line 6-cylinder turbocharged engine was developed for Che Datsun 280ZX in order to achieve higher performance and improved fuel economy. The Electronic Concentrated Engine Control System (ECCS), controlled by microprocessor, is provided for this 2.8 liter turbocharged engine. ECCS controls fuel injection, ignition timing, EGR rate and idling speed. It solved the problems related to power and fuel economy by optimizing the control parameters. Further, this system contains a barometric pressure compensator and a detonation controller; thus, the performance of this engine is efficient over a wide range of circumstances and fuel octane ratings. During the development of the engine, computer simulation was employed to predict engine performance and select turbocharger size, valve timing and other important factors.

Nissan's new 2.4-liter in-line, 4-cylinder gasoline engine, the “KA24E,” was developed for the worldwide automobile market, but exclusively for the North American market. It has been released for Nissan's new 1989 model, high-performance sports car, the “240SX”, and will also be mounted in such forthcoming models as the new 1990 “AXXESS”. The major objectives in developing this new engine were to achieve high performance at practical driving speeds, especially at low- and middle-engine speeds, quiet engine operation, reliability, fuel economy and serviceability, all of which are essential factors in daily driving. For realizing these objectives, multi-valves, aerodynamic intake ports, a high-rigidity cylinder block, a silent single timing chain, and hydraulic valve lash adjusters were incorporated into this engine. Furthermore, to develop the engine, almost all components were redesigned using computer design techniques, and checked by extensive testing.

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.

Some automakers have been studying variable compression ratio (VCR) technology as one possible way of improving fuel economy. In previous studies, we have developed a VCR mechanism of a unique multiple-link configuration that achieves a piston stroke characterized by semi-sinusoidal oscillation and lower piston acceleration at top dead center than on conventional mechanisms. By controlling compression ratio with this multiple-link VCR mechanism so that it optimally matches any operating condition, the mechanism has demonstrated that both lower fuel consumption and higher output power are simultaneously possible. However, it has also been observed that fuel consumption does not reduce further once the compression ratio reached a certain level. This study focused on the fact that the piston-stroke characteristic obtained with the multiple-link mechanism is suitable to a longer stroke.

The suspension system of the Nissan Stanza was specifically designed for use on a front-wheel-drive car. It was developed with the idea that the new suspension should be compact and light, and afford a comfortable ride as well as good stability and controllability. Furthermore, it should have excellent noise and vibration characteristics. To achieve these objectives we adapted a strut suspension for both the front and rear, and careful consideration was given to the fundamental specifications. In addition, some new ideas were applied for the layout of the suspension.

Nissan has now developed a second-generation ceramic turbocharger, improving upon its original ceramic turbocharger in order to meet the increasingly demanding requirements of drivers.

It is well understood that using lower viscosity engine oils can greatly improve fuel economy [1, 2, 3, 4]. However, it has been impossible to evaluate ultra-low viscosity engine oils (SAE 0W-12 and below) utilizing existing fuel economy test methods. As such, there is no specification for ultra-low viscosity gasoline engine oils [5]. We therefore developed firing and motored fuel economy test methods for ultra-low viscosity oils using engines from Japanese automakers [6, 7, 8]. This was done under the auspices of the JASO Next Generation Engine Oil Task Force (“TF” below), which consists mainly of Japanese automakers and entities working in the petroleum industry. Moreover, the TF used these test methods to develop the JASO GLV-1 specification for next-generation ultra-low viscosity automotive gasoline engine oils such as SAE 0W-8 and 0W-12. In developing the JASO GLV-1 specification, Japanese fuel economy tests and the ILSAC engine tests for evaluating engine reliability were used.

This paper describes a newly developed microcomputer-based drowsiness warning system, which detects changes in the driver's alertness through his steering behavior. In developing this system, we first quantified several levels of alertness based on such physiological factors as brain activity and blinking. Tests were then conducted in which drivers fell into different degrees of drowsiness. Using the quantified alertness levels, we defined the “drowsy driver” and found unique steering patterns that could not be seen in normal driving. These patterns were entered into the memory unit of the microcomputer. When the sensor built into the steering wheel detects a drowsy steering pattern, the microcomputer recognizes the driver's drowsiness and activates a buzzer to warn the driver. In this paper, the process of determining the alertness levels is explained, along with the steering characteristics of the drowsy driver.

To reduce engine exhaust emissions, we have had to deal with this global environmental problem from the fuel side by introducing oxygenated fuels, reducing the RVP and using low aromatics. But when we change the fuel components and distillation, we must take note about how these affect the engine driveability. We have used T50, T90, RVP and so on as the fuel index up to the present. It is possible to characterize the fuel from one aspect, but these indexes don't always represent the real feature of the fuel. In this paper we propose a New Driveability Index (here in after referred to as NDI) that is more realistic and accurate than the other fuel indexes. We used a 1600cc DOHC L4 MPI type engine. We used Model Gasolines and Market Gasolines, see Appendix(1), (2) and (3), and tested them according to the Excess Air Ratio Response Test Method (here in after referred to as λ-R Test) that was suggested in SAE paper #930375, and we calculated the NDI statistically.

New technologies are needed to reduce cold-start emissions in order to meet the more stringent regulations that will go into effect in Europe (EC2000 or EC2005) and in California (ULEV), especially for larger engines such as 6- and 8-cylinder units. One new technology in this regard is the electrically heated catalyst (EHC). However, the use of EHCs alone is not sufficient to achieve the necessary reduction in emissions. This paper discusses techniques for effectively combining the elements of an EHC system, including the introduction of secondary air into the exhaust, improved control of the air/fuel ratio, and an electric power supply method for EHCs. It is shown that it is more effective to promote exothermic reactions in the exhaust manifold than at the EHC. A suitable method for this purpose is to introduce secondary air into the exhaust near the exhaust valves.