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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.

Hydraulic engine mounts(HEM) are replacing conventional rubber mounts to provide better ride quality and to reduce noise. However, detailed analysis of the HEM is needed to predict ideal performance conditions. In this study, the optimum design of a HEM is modelled using design optimization theory for a dynamic absorber. After determining ideal behavior by simulation, an experimental mounts is designed and tested to verify the model.

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.

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.

In the past few years, car navigation and cellular phone system are rapidly increased in Japan and vehicle information and communication system (VICS), the public traffic information service started in 1996, accelerates realization of ITS world. This rapid movement causes drivers to want more information on not only traffic jam but also other versatile items like parking availability, weather report and the latest news, etc. via cellular phone network. This paper describes the on-demand information service with the interactive human interface by operators and the development of the information center and the in-vehicle system to realize it.

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 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.

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.

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.

As a new generation sports car engine to lead the field in the 1990s, a 3.0 liter, 60°V, type 6 cylinder, 4 cam, 24 valve engine (VG30DETT) has been developed to achieve the utmost in high performance levels and reliability. it has been mounted on the new model 300ZX and announced in the North America and Japanese markets. The VG30DETT engine is based on the previous VG30DE engine (the engine mounted on the former model 300ZX designed for the market in Japan). The main components, the major driving and the lubrication systems including such parts as the crank shaft,con-rod, cylinder block, piston, exhaust manifold, and oil pan of the VG30DE were thoroughly reviewed and revised. The VG30DETT engine is the result of redesigning the structure of the engine itself and its parts and components to assure durability under, high-level performance requirements.

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.

Clarifying the impact of ETBE 8% blended fuel on current Japanese gasoline vehicles, under the Japan Clean Air Program II (JCAPII) we conducted exhaust emission tests, evaporative emission tests, durability tests on the exhaust after-treatment system, cold starting tests, and material immersion tests. ETBE 17% blended fuel was also investigated as a reference. The regulated exhaust emissions (CO, HC, and NOx) didn't increase with any increase of ETBE content in the fuel. In durability tests, no noticeable increase of exhaust emission after 40,000km was observed. In evaporative emissions tests, HSL (Hot Soak Loss) and DBL (Diurnal Breathing Loss) didn't increase. In cold starting tests, duration of cranking using ETBE 8% fuel was similar to that of ETBE 0%. In the material immersion tests, no influence of ETBE on these material properties was observed.

During the last decade, fuel economy mandates (CAFE regulations) have driven engine downsizing and down-speeding trends. More recently, downsized turbos are percolating down to heavier SUVs and trucks. Larger/heavier vehicles require high torque engines to provide attractive dynamic performance. While higher torque requirements can be satisfied with new innovations like the variable compression engine, larger and more upscale vehicles also need to deliver higher quietness requirements. For this, the vibration control system for combustion induced forces with high torque engines become very important. To address both dynamic performance and quietness requirements, active engine mounts have been previously adopted, however challenges for light-weighting, downsizing, and costs have still persisted.

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.

The purpose of this study was to develop a simple optimization method for use in designing vibration insulators. With this method, stiffness, location and inclination of each insulator are used as design parameters. A performance index consisting of vehicle modal parameters expressed as eigenvalues and eigenvectors has been constructed to evaluate low-frequency idle/shake performance and higher frequency vibration performance involving road/engine inputs. Using this performance index and the sensitivity of the modal parameters, a designer can easily find a suitable direction for optimizing mount performance and thereby obtain a stable solution. The new method was employed to optimize an engine mount system. Experimental data obtained on the system validated the accuracy of the calculated results and showed an improvement in idle/shake performance. This method is a useful tool in designing optimum vibration insulators.

An investigation was made of the relationship between the driving speed at the time of impact and the injury levels suffered in accidents. The results showed that a 5 km/h or more reduction in collision speed tends to mitigate injury severity. Using sensors and brake actuators already in practical use, we have started to research a braking system aimed at reducing the collision speed by at least 5 km/h in rear-end collisions. The system estimates the risk of a collision with the vehicle ahead. If it judges there is a very high possibility of a collision, it applies the brakes.

This paper describes an experimental modal synthesis method for determining the noise characteristics of coupled acoustic-structural systems. This method was developed to provide an essential tool for analyzing passenger compartment noise levels. With this method, it is possible to obtain the coupled acoustic-structural parameters directly from experimental measurements of noise and vibration. The resulting modal parameters provide the basis for predicting how structural modifications will affect interior noise characteristics. This paper presents the theory on which the method is based and gives examples of its application to passenger compartment noise analyses.

This Paper Presents the world's first active noise system for production vehicle implementation. Adopted in the new middle size FF car model, this epoch-making system dramatically reduces the booming noise caused by the second-order harmonic of engine revolution. This is accomplished by using an adaptive control theory based on digital signal processing technology and a digital signal processor (DSP). The system basically employs a multiple error filtered-x LMS algorithm, to which an new algorithm was added to achieve the maximum noise reduction effect under a condition of stable control in a compact system for production vehicle application.