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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 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.

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.

The primary objective in design is to achieve the target value of the design's response function. If a design fails to achieve the target value, it most likely fails in two ways: inconsistent functional output and in design involving multiple response functions, unable to converge to the multiple target values in spite of iterative adjustment of the design parameters. The former is symptom of a design not able to perform in the presence of variability, i.e., noise. The latter is symptom of a design that fails to perform in the presence of functional coupling. Both problems are best addressed at the conceptual stage of the design at which only design solution that is inherently robust to noise and functionally uncoupled is entertained. If this is not possible, the alternative is to exploit the interaction between control variables and variables that are sources of noise and functional coupling to render the design insensitive to them.

The durability test with road-load input is necessary for evaluating durability of body and chassis structure in automotive applications. This paper shows the method to analyze road-load input to a suspension system for development of a simple component level bench test. This method enables the extraction of the essential inputs to evaluate the durability of suspension parts using the transfer function (frequency response function) measured by Multi-axial Road Simulator and wheel force transducers. These extracted inputs contribute to development of a new realistic component bench test.

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.

This paper describes a newly developed HC-adsorption three-way catalyst and adsorption system that reduce cold-start HC emissions with high efficiency. This system is the first of its kind anywhere in the world to be implemented on production vehicles. An overview is given of the various improvements made to achieve higher cold-start HC conversion efficiency. Improvement of conversion performance was accomplished by (1) increasing the thermal stability of the HC adsorbent, (2) improving desorbed HC conversion efficiency and durability and (3) optimizing the geometric surface area (GSA) of the substrate. Concretely, the thermal stability of the adsorbent was improved by enhancing the high-temperature durability of zeolite. Improvement of desorbed HC conversion efficiency was accomplished by improving the OSC material so as to match the temperature rise characteristic and usage temperature of the catalyst.

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 combustion process after auto-ignition is investigated. Depending on the non-uniformity of the end gas, auto-ignition could initiate a flame, produce pressure waves that excite the engine structure (acoustic knock), or result in detonation (normal or developing). For the “acoustic knock” mode, a knock intensity (KI) is defined as the pressure oscillation amplitude. The KI values over different cycles under a fixed operating condition are observed to have a log-normal distribution. When the operating condition is changed (over different values of λ, EGR, and spark timing), the mean (μ) of log (KI/GIMEP) decreases linearly with the correlation-based ignition delay calculated using the knock-point end gas condition of the mean cycle. The standard deviation σ of log(KI/GIMEP) is approximately a constant, at 0.63. The values of μ and σ thus allow a statistical description of knock from the deterministic calculation of the ignition delay using the mean cycle properties

This paper describes the HMI, navigation and telematics systems developed specifically for the Nissan LEAF electric vehicle to dispel drivers' anxieties about operating an EV. Drivers of EVs will need to understand various new kinds of information about the vehicle's operational status that differ from conventional gasoline-engine vehicles. Additionally, owing to the current driving range of EVs and limited availability of charging stations, drivers will want to know acccurate the remaining driving range, amount of power and the latest information about charging station locations. It will also be important to ensure that people unfamiliar with EVs will be able to operate them easily as rental cars or in car-sharing systems without experiencing any inconvenience.

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.

The objective of this work was to develop an experimental system to support development and validation of a model for the lubrication of two-piece Twin-Land-Oil-Control-Rings (hereafter mentioned as TLOCR). To do so, a floating liner engine was modified by opening the head and crankcase. Additionally, only TLOCR was installed together with a piston that has 100 micron cold clearance to minimize the contribution of the skirt to total friction. Friction traces, FMEP trend, and repeatability have been examined to guarantee the reliability of the experiment results. Then, engine speed, liner temperature, ring tension, and land widths were changed in a wide range to ensure all three lubrication regimes were covered in the experiments.

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.

Nissan has added ball bearings to its “High-flow Ceramic Turbocharger”(1) (introduced in 1987) to improve acceleration response by reducing friction loss. The following programs were carried out in applying ball bearings to the turbocharger: Optimum bearing size and material were selected to assure long life; lubrication techniques were employed to achieve compatibility between acceleration response and durability; a thrust support system was designed to assure that the ball bearings endure thrust load which varies in direction and magnitude during engine operation; and the squeeze film damper was optimized to keep the turbocharger silent. These innovations have resulted in a practical ball-bearing turbocharger, which has been installed in Nissan's most recent Skyline model(released in May 1989). This is the first time a ball-bearing turbocharger has been applied to a passenger car.

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.