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Previous reports have already described the details of engine start-shock and the mechanism of vibration mechanism in a stationary vehicle. This vibration can be reduced by optimized engine and motor generator vibration-reduction controls. A prediction method using a full-vehicle MBD model has also been developed and applied in actual vehicle development. This paper describes the outline of a new method for the hybrid system of mechanical power split device with two motors that predicts engine start-shock when the vehicle is accelerating while the engine is stopped. It also describes the results of mechanism analysis and component contribution analysis. This method targets engine start-shock caused by driving torque demand during acceleration after vehicle take-off. The hybrid control system is modeled by MATLAB/Simulink. A power management and motor generator control program used in actual vehicles is installed into the main part of the control system model.

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.

Previous studies and recent practical aerodynamic evaluations have shown that aerodynamic drag of passenger vehicles with “ground simulation” with moving ground and rotating wheels may increase in some cases and decrease in other cases relative to the fixed ground and stationary wheel conditions. Accordingly, the effects of the ground simulation on the aerodynamic drag should be deeply understood for further drag reduction. Although the previous studies demonstrated what is changed by the ground simulation, the reason for the change has not been fully understood. In this article, the effects of wheels and wheel houses attachment and those by the ground simulation with ground movement and wheel rotation on the aerodynamic drag were investigated by quantification of the underfloor flow that plays a crucially important role on the formation of vortical structure around vehicles.

This paper deals with friction under wet condition in the disk brake system of automobiles. In our previous study, the variation of friction coefficient μ was observed under wet condition. And it was experimentally found that μ becomes high when wear debris contains little moisture. Based on the result, in this paper, we propose a hypothesis that agglomerates composed of the wet wear debris induce the μ variation as the agglomerates are jammed in the gaps between the friction surfaces of a brake pad and a disk rotor. For supporting the hypothesis, firstly, we measure the friction property of the wet wear debris, and confirm that the capillary force under the pendular state is a factor contributing to the μ variation. After that, we simulate the wear debris behavior with or without the capillary force using the particle-based simulation. We prepare the simulation model for the friction surfaces which contribute to the friction force through the wear debris.

The use of ceramic insulation to reduce engine heat loss and thus improve fuel economy was examined but found to be detrimental rather than advantageous. This paper analyzes the reasons and presents an alternative approach, namely minimizing the heat transfer area. Experiments were conducted to determine the effects of surface smoothness on BSFC, output torque, heat release rate and piston temperature. It was found that with a mirror-finished combustion chamber, heat loss is decreased and consequently engine output is raised, while fuel consumption is lowered. The percentage reduction in heat loss was ascertained by numerically simulating combustion and was confirmed by FEM analysis of piston thermal distribution.

This paper describes the preliminary development of an on-board integration network for vehicle dynamics. The underlying philosophy is explained and the basic requirements are set forth. A design conforming to these requirements is presented and the experiments conducted to optimise the physical layer are described. An original token passing protocol is proposed for the access method and evaluated in comparison with the contention method by means of a specially devised simulation system.

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.

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.

This paper presents a technique to predict the suspension load in early design stage when a passenger car with low profile tires goes over a bump. The suspension load is simulated by using ADAHS (Automatic Dynamic Analysis of Mechanical Systems). The tire was modeled as a radial spring with non-linearity decided by test data. The simulated results of suspension load agreed with the test data. The effect of shock absorber characteristics and spring bumper stiffness on the suspension load was studied by using this simulation model. As a result, the optimum specification for suspension load reduction was taken.

Oil film thickness is one of the most important issues for optimization of bearing design. A technique has been developed to measure oil film thickness by noting the change in capacitance between the shaft and a thin-film electrode of several micrometers thickness formed on the surface of a bearing. The authors applied this technique to the main journals of an automobile engine and measured the oil film thickness up to maximum speed and full load. The oil film thickness became thinner with increased engine load, and then turned thicker with increased engine speed.

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 hybrid system has the typical advantage that it can realize various types of system control, because the system has two power units, engine and motor. On the other hand, however, constraints are increasing due to the complexity of the vehicle system. Compared to the conventional HILS construction and application, there are mainly two typical characteristics or themes for HV-HILS (i.e. HILS for hybrid vehicle control development). Firstly, HV-HILS requires full vehicle simulation environment, because the plural ECU control logic is intricately intertwined. Secondly, recent HILS system needs to run with more accurate or complicated plant models which are necessary to develop more accurate vehicle control logic.

In a stage of designing a CVJ boot, analytic conditions of FEA method are established so that values calculated with the FEA method coincide with the actually measured values. This has made it possible to predict the life of the boot under bench testing. Furthermore, the boot field life can also be predicted by the minor rule based on the joint-angle frequencies of a vehicle. As a result, it has become possible to determine an optimal configuration in the design stage and to decrease the number of test cycles, resulting in reduced development lead time.

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 paper describes how the 2-degree-of-freedom control concept may be applied to an active front-and-rear steering control system. The configuration of the system is explained as is the manner in which the control strategy can be devised. Simulation and test results confirm that vehicle characteristics may be varied to achieve specific aims and that steering response and vehicle stability can be independently improved.

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.

The behavior of spray injections to turbulent duct flows from a slit injector for direct-injection gasoline engines was investigated using a combination of large eddy simulation (LES) and Lagrangian discrete droplet model (DDM). As a result, diffusion of droplets in stronger turbulent flows was observed at a later stage of the injection. Moreover, we compared calculation and experimental results by generating a pseudo-particle image from the calculation result.

Toyota has been evolving a hybrid system since introducing the first mass-production hybrid vehicle in 1997 in response to the increasing automotive-related issues of CO2 emissions, energy security, and urban air pollution. This paper describes a newly developed hybrid system design and its performance. This system was developed with the main purpose to improve fuel consumption, especially for better real world fuel consumption; and to enhance its compatibility with multiple vehicle adoption by downsizing and reducing the weight of its components. At the same time, the hybrid system achieved improved power performance while satisfying stringent emission regulations in the world.