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For a numerical model of vibro-acoustic coupling analysis, such as a vehicle noise and vibration, both structural and acoustical dynamic characteristics are necessary to replicate the physical phenomenon. The accuracy of the analysis is not enough for substituting a prototype phase with a digital phase in the product development phases. One of the reasons is the difficulty of addressing the interior acoustical characteristics due to the complexity of the acoustical transfer paths, which are a duct and a small hole of trim parts in a vehicle. Those complex features affect on the nodal locations and the body coupling surface of acoustic mode shapes. In order to improve the accuracy of the analysis, the physical mechanisms of those features need to be extracted from experimental testing.

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.

The ways in which vehicles are used in the field are continually becoming more diverse. In order to provide the optimum solution with respect to performance and weight, it is necessary to be able to assure vehicle endurance reliability with a high degree of accuracy in relation to the manner of use in each market. This situation has increased the importance of accurately quantifying the ways in which vehicles are used in the field and of designing vehicles with sufficient endurance reliability to match the usage requirements. This report presents a “market model” by which the manner of usage in the field can be treated quantitatively using combinations of environmental factors that influence the road load, drive load and corrosion load, representing typical loads vehicles must withstand.

Since interior noise has a strong effect on vehicle salability, it is particularly important to be able to estimate noise levels accurately by means of simulation at the design stage. The use of sensitivity analysis makes it easy to determine how the analytical model should be modified or the structure optimized for the purpose of reducting vibration and noise of the structural-acoustic systems. The present work focused on a structural-acoustic coupling problem. As the coefficient matrices of a coupled structural-acoustic system are not symmetrical, the conventional orthogonality conditions obtained in structural dynamics generally do not hold true for the coupled system. To overcome this problem, the orthogonality and normalization conditions of a coupled system were derived by us. In this paper, our sensitivity analysis methods are applied to an interior noise problem of a cabin model.

Detergent additives in automotive gasoline fuel are mainly designed to reduce deposit formation on intake valves and fuel injectors, but it has been reported that some additives may contribute to CCD formation. Therefore, a standardized bench engine test method for CCDs needs to be developed in response to industry demands. Cooperative research between the Petroleum Association of Japan (PAJ) and the Japan Automobile Manufacturers Association, Inc. (JAMA), has led to the development of a 2.2L Honda engine dynamometer-based CCD test procedure to evaluate CCDs from fuel additives. Ten automobile manufacturers, nine petroleum companies and the Petroleum Energy Center joined the project, which underwent PAJ-JAMA round robin testing. This paper describes the CCD test development activities, which include the selection of an engine and the determination of the optimum test conditions and other test criteria.

Achieving a multi-cylinder engine with excellent noise/vibration character sties and low friction at the main bearings requires an optimal design not only for the crankshaft construction but also for the bearing support system of the cylinder block. To accomplish that, it is necessary to understand crankshaft system behavior and the bearing load distribution for each of the main bearings. Crankshaft system behavior has traditionally been evaluated experimentally because of the difficulty in performing calculations to predict resonance behavior over the entire engine speed range. A coupled crankshaft-block analysis method has been developed to calculate crankshaft system behavior by treating vibration and lubrication in a systematic manner. This method has the feature that the coupled behavior of the crankshaft and the cylinder block is analyzed by means of main bearing lubrication calculations. This paper presents the results obtained with this method.

Engines that not only produce less noise but also provide good sound quality have been in increasing demand recently. Discomforting noise can sometimes be heard, however, during acceleration as the engine reaches higher levels of power and speed. This paper presents the results of a study into the bending vibration of the crankshaft-flywheel system, which clarify the mechanism producing discomforting noise during acceleration. Based on that study, a flexible flywheel has been developed which effectively reduces crankshaft bending vibration that is closely related to the frequency range of the discomforting noise. As a result, acceleration sound quality is greatly improved.

This paper describes an image processing method for recognizing white lines on the road ahead to accomplish automatic lane tracking. The behavior of detected points on the white lines can be regarded as multi-channel time-series data. The stochastic behavior of each point correlates with not only its own past behavior but also the behavior of other points around it. Behavior is identified by using a multi-variable auto-regressive (AR) model. This method can estimate the road configuration ahead logically even if the points cannot be detected clearly because a line is discontinuous or is hidden by a forward vehicle.

Recently, it has been very important to reduce the noise, especially the Squeak and Rattle noise, for improving customer appeal of passenger vehicles. The Squeak and Rattle noise occurring inside the car cabin during vehicle operation is an especially large problem. This paper describes a newly developed measurement technology that uses the developed signal processing using the Beam-forming method and vibration sensor to identify the Squeak and Rattle noise sources, making it possible to determine effective countermeasures quickly. This new technology is used to identify all Squeak and Rattle noises at a time among many different noises, for example Wind noise, Engine noise and Road noise occurring during vehicle operation, and is expected to shorten substantially the time needed for noise analysis and contribute to quality improvements.

A safety support system that uses information received from the road infrastructure is being developed in a project sponsored by the Ministry of Land, Infrastructure and Transport. The purpose of this system is to reduce the number of accidents at intersections and on highways. The system is now being tested in an experimental vehicle. This paper describes what kind of information is helpful to drivers based on the experimental results.

A seat vibration prediction technique using a substructure synthesis method was developed for use in ride comfort evaluations. The human body was modeled as a vibration transfer matrix using the mean apparent mass of human subjects, based on data measured in advance. Seat vibration characteristics were measured with rigid masses on the seat. The measured data and vibration transfer matrix of the human body were synthesized using a substructure synthesis method, to predict vibration of the seat cushion and backrest in an occupant-loaded condition without actually using human subjects. Results showed that seat vibration predicted with this method was very similar to, and more repeatable than, that obtained experimentally with human subjects.

This paper describes a new 5.6-liter DOHC V8 engine, VK56DE, which was developed for use on a new full-size sport utility vehicle and a full-size pickup truck. To meet the demands for acceleration performance when merging into freeway traffic, passing or re-acceleration performance from low speed in city driving and hill-climbing or passing performance when towing, the VK56DE engine produces high output power at top speed and also generates ample torque at low and middle engine speeds (90% of its maximum torque is available at speeds as low as 2500 rpm). Furthermore, this engine achieves top-level driving comfort in its class as a result of being derived from the VK45DE engine that was developed for use on a sporty luxury sedan. Development efforts were focused on how to balance the required performance with the need for quietness and smoothness.

An Adaptive Cruise Control system with stop-and-go capability has been developed to reduce the driver's workload in traffic jams on expressways. Based on an analysis of driving behavior characteristics in expressway traffic jams, a control system capable of modeling those characteristics accurately has been constructed to provide natural vehicle behavior in low-speed driving. The effectiveness of the system was evaluated with an experimental vehicle, and the results confirmed that it reduces the driver's workload. This paper presents an outline of the system and its effectiveness along with the experimental results.

This paper describes an image processing system for tracking a traffic lane by recognizing white lines on the road ahead. The system utilizes the features of the white lines and the Hough transformation to detect white line candidate points in images taken with a CCD camera. The parameters of the road configuration and vehicle attitude are estimated with an extended Kalman filter. This system has been applied to achieve a lane-keeping assistance system that provides steering control based on the host vehicle’s lateral position in its lane.

Eliminating squeal noise generated during braking is an important task for the improvement of vehicle passengers' comfort. Considerable amount of research and development works have been done on the problem to date. In this study, we focused on the analyses of friction self-excited vibration and brake part resonance during high frequency brake squeal. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding velocities. Its vibration frequency can be calculated in relation to the mass and stiffness of the pad sliding surface. Frequency responses of the brake assembly were measured and the vibration modes of the pad, disc and caliper during squeal were identified through modal analysis. Further study led to the development of a computer simulation method for analyzing the vibration modes of brake parts. Analytical results obtained using the method agreed well with the corresponding experimental data.

Digital signal processors (DSPs) are being used widely for sound field reproduction. However, it is difficult to apply a DSP to a car audio system because of the complicated acoustic characteristics of the passenger compartment. The authors have developed a new car audio system which employs special DSP software and a new speaker layout to provide excellent presence. The DSP has five output channels to generate stereophonic reflection from the front and rear speakers. The DSP software is programmed for each individual car model. A center speaker and A-pillar tweeters are used to produce a natural sound field in front through effective utilization of reflection from the windshield. This system is featured in 1992 Nissan models.

In making driver workload assessments, it is important to evaluate the driver's level of brain activity because the operation of a motor vehicle presumably involves higher-order brain functions. Driving on narrow roads in particular probably imposes a load on the driver's brain functions because of the need to be cognizant of the tight space and to pay close attention to the surroundings. Test vehicles were fitted with a functional near-infrared spectroscopy (fNIRS) system for measuring bloodstream concentrations at 32 locations in the frontal lobe of the participating drivers in order to evaluate their levels of mental activity while driving on narrow roads. The results revealed significant increases in cerebral blood flow corresponding to the perceived workload. This suggests that increases in cerebral blood flow can be used as an effective index for estimating mental workloads.

The Hybrid FE-SEA method has been used to create fast/efficient model of structure-borne noise in a fully trimmed vehicle from 200Hz to 1kHz. A joint paper is presented which highlights the method and modelling process along with extensive validation results. This paper describes the use of the model to analyze structure borne noise in the full vehicle, design and evaluate the impact of counter-measures. One of the key attributes of the Hybrid FE-SEA method is the ability to predict noise transfer paths in the vehicle. First, results from a Noise Path Analysis are used to identify key contributors to interior noise in the 200Hz-1kHz frequency range. Next potential design strategies for reducing interior noise are introduced along with implications on the model. Finally, sample prediction results illustrating the impact of design changes on interior noise levels are shown along with preliminary experimental validation results.

This paper describes a new 4.5-liter V8 engine, VH45DE, which was developed for use in the INFINITI Q45 sporty luxury sedan that was released in the U.S. and Japanese markets in November 1989. The many V8 engines in use around the world can be broadly devided into two categories. One category is characterized by ample torque at low engine speed and relatively large engine displacement. The other category is characterized by enhanced performance at relatively high engine speeds. The VH45DE engine is a new-generation V8 powerplant that delivers smooth power output at top-end speed and also generates ample torque at low engine speed to maintain good idle stability, and accomplishes it all with the smallest possible displacement. Development efforts were focused on two main goals. The first was to achieve efficient intake air charging. This has been accomplished the intake air resonant point at a relatively high engine speed through appropriate intake branch and collector tuning.

This paper presents Nissan's new four-valve-per-cylinder direct injection (DI) diesel engine series consisting of a 2-liter class and 3-liter class. These engine series provide substantially improved power output along with lower noise and vibration levels, which have been traditional drawbacks of DI diesel engines. Nissan developed this engine series in response to the heightened need in recent years for passenger-car DI diesel engines with superior thermal efficiency, a characteristic advantageous for reducing CO2 emissions.