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The present paper describes an application of non-parametric shape optimization to disc brake squeal phenomena. A main problem is defined as complex eigenvalue problem in which the real part of the complex eigenvalue causing the brake squeal is chosen as an objective cost function. The Fre´chet derivative of the objective cost function with respect to the domain variation, named as the shape derivative of the objective cost function, is evaluated using the solution of the main problem and the adjoint problem. A selection criterion of the adoptive mode number in component mode synthesis (CMS), which is used in the main problem, is presented in order to reduce the computational error in complex eigenvalue pairs. A scheme to solve the shape optimization problem is presented using an iterative algorithm based on the H1 gradient method for reshaping. For an application of the optimization method, a numerical example of a practical disc brake model is presented.

This research proposes an automatic measuring method for the impulse noise of the valve system in engine production line. This research is composed of the following two parts. (1) The most suitable method for indicating the impulse noise of the valve system - the representative characteristic values - is selected from the general measuring methods for impulse noise. As the result, the crest factor in the frequency band above 1kHz became optimal. (2) By detailed sensory characteristic analysis it was found that impulse noise can be heard better with increasing frequency and that there is little influence in the frequency band with the same frequency as the background noise. Thus the crest factor was obtained for each frequency, and the sensory test for the impulse noise of the valve system is deduced by this linear coupling. As the result of multiple reguression analysis, a high accuracy prediction equetion with a multiple correlation coefficient of 0.91 has been obtained.

A new automatic transmission, engineered from concept for “intelligent” and “anti-aging” (long life), has been designed and developed for TOYOTA's luxury passenger car, LEXUS LS400. This system, which has resulted in silky-smooth shift quality without changes in the long term, is composed of a transmission computer that interacts with engine computer, a number of sensors, an electronically controlled hydraulic unit with linear solenoid valves and assorted devices. As new control logic being developed with the aid of computer simulation to achieve distinction, the hydraulic and engine controls are combined in this system. There is a “feedback control”, where the clutch pressure is controlled according to the rate of acceleration and compensated for dispersion to applied pressure, engine torque and/or the coefficient of dynamic friction of clutches, and at the same time engine torque is reduced by retarding ignition timing.

Recently, the quietness of the passenger compartment has become an important quality for a vehicle, and as a result, various improvements have been made to reduce the passenger compartment noise level. Particularly engine noise, a major source of interior noise, has been studied for many years and has recently been reduced to an acceptable level. As a result, air intake noise, which was a relatively minor noise source in the past, has rapidly become a noticeable noise source. This paper describes a newly developed air intake system testing apparatus, which enables us to evaluate intake noise at an early stage of engine development and also describes how the new apparatus and approach was used to develop a low-noise air intake system. This apparatus, called the PULSATION SIMULATOR, reproduces intake pulsations in the actual engine using its cylinder head and reproduces intake air flow precisely.

A new experimental method, that enables to estimate the body and driveline sensitivity to unit transmitting error of a hypoid gear for automotive rear axle gear noise, has been developed. Measurements were made by exciting the tooth of the drive-pinion gear and that of the ring gear separately using the special devices designed with regard to simulation of acceleration and deceleration. The characteristic of this method is to estimate the forces at the contact point of the gears. Estimation of these forces is carried out under the condition that the higher stiffness is provided by the tooth of the drive-pinion gear and that of the ring gear, compared with the stiffness of the driveshafts and that of the propeller shaft etc., and relative angular displacement of the torsional vibration between the teeth of the drive-pinion gear and those of the ring gear is constant.

A communication system that uses roadside beacons to broadcast road and traffic information and private messages to vehicles has been developed. The system, called Road/Automobile Communication System (RACS), was the result of a joint research project involving the Public Works Research Institute and 25 private-sector corporations. This paper contains an outline of RACS and of an onboard system developed by TOYOTA and presents the results of field tests conducted in the Tokyo area. The results not only verify the capability of the RACS system and the effectiveness of the in-vehicle equipment but also indicate the potential of such a beacon based network to improve traffic jam and driving safety whilst providing enhanced communication facilities without increasing radio-wave congestion.

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.

The synchronous belt employed in the valve train of automotive engines is operated under fluctuating load. Two types of the belt vibration are observed. One is the well-known lateral vibration. The other is the vibration in the belt running direction which may cause the resonant vibration of the camshaft rotation and may affect the belt life. The purpose of this paper is to describe an analysis of the latter vibration. This vibration was analyzed using the model composed of the inertia moment of the camshaft system and the nonlinear elasticity of the belt in the running direction. The predicted resonant frequency and amplitude were in good agreement with the measured ones. The influence of each factor of the model on the vibration was also investigated. The stiffness in the belt running direction that is determined by the tooth distortion When the belt engages with the pUlley should be increased to reduce the amplitudes of the resonant Vibration.

In today's manufacturing environment, it has become necessary to develop intelligent robots which are adaptable to changing process requirements. To attain this goal, a key robot technology involving new real time control algorithms has been developed. The algorithms govern the 3D position and orientation of the robot. Initially, a simulation method was used to study the achievable system accuracy. From the results of computer simulations, it was determined that the algorithms can achieve a high tracking accuracy of ± 0.5 mm at a velocity of 300 mm/sec (4 times higher than conventional sensory control speeds). For a sensory feedback system, delays in tracking movements are inherent. This is due to the calculation time required for control and to the servo response. To solve this problem, a sensor is positioned at a predetermined distance in advance of the tool in the direction of travel.

This report relates to that kind of rumble generated in the passenger compartment during acceleration which is caused by intake noise. The rumble is a rough, unpleasant noise that comes into the passenger compartment during acceleration. This noise was reported to be caused by the resonant bending vibration of the crankshaft. However, the writer and associates found that intake noise from the air inlet could also cause the rumble in the passenger compartment as reported herein. By a modal analysis of the air column vibration generated in the inlet system parts and analysis of the air column vibration response to the force input from each cylinder, the writer and associates determined that the standing wave generated in the surge tank was the cause of the rumble. By modifying the shapes of surge tank models for computer simulation that had been used in predicting booming noise, etc., it became possible to predict rumble level due to intake noise through calculation.

With the progress of super computers in recent years, a number of studies on “Computational Fluid Dynamics” (CFD) have been carried out, and various schemes for Navier-Stokes equations have been presented. Similar methods have also been applied to automotive engineering - aerodynamics, for exampre - in order to determine flow phenomena. In this paper, the application of numerical simulations to the flow cavitation that occurs in some part of orifices in the vehicle hydraulic system, will be discussed. Authors have developed a CFD program for the clarification of flow phenomena in such orifices. Using the relationship between calculated results and measured results of noise levels in such orifices, a new method for estimation of the occurrence of flow cavitation has also been developed. As a result, a new orifice configuration capable of preventing the cavitation has been designed.

Brake squeal is caused by dynamic instability, which is influenced by its dynamic unstable structure and small disturbance of friction force variation. Recently, FE Analysis of brake squeal is applied for brake design refinements, which is based on dynamic instability theory. As same as the refinement of brake structure is required for brake squeal reduction, the refinement of pad materials is also required for brake effectiveness and brake squeal reduction. It is well known that friction film, which is composed of polymers like phenol formaldehyde resin and so on, influences for friction coefficient. Therefore it is expected that the refinement of polymers in pad materials enable higher brake effectiveness and less brake squeal. In this paper, Molecular Dynamics is applied for the friction force variation of polymers in pad materials. The MD simulation results suggest the reduction method of friction force variation of polymers.

A full vehicle multi-body dynamic (MBD) model with suspension control system is developed for fatigue life prediction under rough road condition. The model consists of tires, a trimmed body, heavy attached parts, powertrain, suspension, joints, and a driver model, and includes a suspension control system that varies characteristics of the suspension according to the rough road inputs. For tires, a commercial MBD tire model is employed with identifiable parameters. The models are simulated to run on the optically measured road surface of the proving ground. Apart from the trimmed body, several important heavy attached parts are modeled separately, that represent dynamic behavior that induces complex body input load. These parts, along with suspension and powertrain systems are connected to the body using nonlinear elements such as joints, springs, and dampers. Contact conditions are used to represent mount bushing, hood lock, stopper rubber, etc.

The finite element method (FEM) is effective for analyzing brake squeal phenomena. Although FEM analysis can be used to easily obtain squeal frequencies and complex vibration modes, it is difficult to identify how to modify brake structure design or contact conditions between components. Therefore, this study deals with a practical design method using sensitivity analysis to reduce brake squeal, which is capable of optimizing both the structure of components and contact conditions. A series of analysis processes that consist of modal reduction, complex eigenvalue analysis, sensitivity analysis and optimization analysis is shown and some application results are described using disk brake systems.

The design of the newly developed Toyota AZ series 4 cylinder engine has been optimized through both simulations and experiments to improve heat transfer, cooling water flow, vibration noise and other characteristics. The AZ engine was developed to achieve good power performance and significantly reduced vibration noise. The new engine meets the LEV regulations due to the improved combustion and optimized exhaust gas flow. A major reduction in friction has resulted in a significant improvement in fuel economy compared with conventional models. It also pioneered a newly developed resin gear drive balance shaft.

With the advance in modularization of engine parts in recent years, there is increased use of plastic-made products in air intake systems. Plastic-made intake manifolds (Fig. 1) provide many advantages including reduced weight, reduced cost, and lower intake air temperatures. However, these manifolds have one disadvantage when compared with conventional aluminum-made intake manifolds, in that they transmit more noise because of their lower material density. For example, plastic intake manifolds of early development often generate flow noise when the throttle is opened quickly. With conventional aluminum intake manifolds, this flow noise had generated, but was not heard. This flow noise is presumed to be generated because of high-speed airflow generated when the throttle is opened quickly, but the mechanism of this noise generation has not been clarified.

Porous material is used at the duct wall in order to reduce air resonance in the air intake duct. High frequency component in the intake noise is reduced by escaping of the air through the duct wall. The relation of attached position, the size and air permeability of the porous material to acoustic behaviors was cleared.

In the present social environment, automobile demands further reduction of fuel consumption and light weight. Now that the reduction of vehicle weight is being pursued, even a slight looseness in each element of an automobile may become a source of vibration and noise due to the lowered rigidity of such an automobile. The quietness of vehicles is urged, spline backlash in the spline mechanism exhibits a problem in some cases. A propeller shaft, a part of the automobile driving system, also has a sliding spline mechanism as shown in Fig. 1. Such a propeller shaft is required to have functions of transmitting high torque driving forces, and absorbing the variation of the vehicle driveline overall length at the same time. Vibration and noise are apt to occur if when torque is applied, there is a significant balance fluctuation or great sliding resistance due to spline backlash.

A description is made of new control methods to improve response of wheel slip regulation. These methods enabled a new Traction Control (TRC) system based on throttle control rather than brake pressure to be developed. Major points are as follows: (1) Use of fuel injection cut-off to minimize delay (2) Additional adaptive throttle control logic By these means, a response nearly equal to that with brake pressure control is achieved at lower cost and with a considerable weight saving. Furthermore, the system, by suppressing noise and vibration, enhances the driver's control ability.

The SEA model of wind noise requires the quantification of both the acoustic as well as the turbulent flow contributions to the exterior pressure. The acoustic pressure is difficult to measure because it is usually much lower in amplitude than the turbulent pressure. However, the coupling of the acoustic pressure to the surface vibration is usually much stronger than the turbulent pressure, especially in the acoustic coincidence frequency range. The coupling is determined by the spatial matching between the pressure and the vibration which can be described by the wavenumber spectra. This paper uses measured vibration modes of a vehicle window to determine the coupling to both acoustic and turbulent pressure fields and compares these to the results from an SEA model. The interior acoustic intensity radiating from the window during road tests is also used to validate the results.