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A transient knock prediction technique has been developed by coupling a zero-dimensional knocking simulation with chemical kinetics and a one-dimensional gas exchange engine model to study the occurrence of transient knock in SI engines. A mixed chemical reaction mechanism of the primary reference fuels was implemented in the two-zone combustion chamber model as the auto-ignition model of the end-gas. An empirical correlation between end-gas auto-ignition and knock intensity obtained through intensive analysis of experimental data has been applied to the knocking simulation with the aim of obtaining better prediction accuracy. The results of calculations made under various engine operating parameters show good agreement with experimental data for trace knock sensitivity to spark advance.

The brake-operated pre-crash seatbelt system retracts the seatbelt webbing by activating an electric motor attached to the seatbelt retractor. Detection of emergency braking is used as a trigger to activate the motor. Retracting the seatbelt helps to reduce an occupant's forward movement due to inertial force acting on the occupant's body during deceleration in braking. Addtionally, retraction of the seatbelt webbing also helps existing occupant restraint devices to work more effectively in a crash. The effectiveness of the pre-crash system was evaluated by considering two conditions combined. One involved the dynamic behavior of the vehicle and occupants prior to a crash. The other concerned the safety performance of the vehicle during the crash event. Experiments were conducted to measure the behavior of the vehicle and occupants under emergency braking prior to a crash.

Indexes of thermal comfort, such as PMV (Predicted Mean Vote: ISO-7730), which have traditionally been applied to houses or buildings, are difficult to be applied to the automotive passenger compartment because of the large thermal differences that exist around vehicle occupants. In this work, the effects of temperature, airflow and solar radiation on passenger comfort in an air-conditioned vehicle interior were analyzed. Based on the results obtained, a method was devised for predicting the feeling of comfort passengers get from the thermal atmosphere in the vehicle interior. This paper explains the necessity of providing a diffused airflow in an air-conditioned passenger compartment, based on the effects of airflow on the feeling of comfort. Further, a new airflow control procedure is proposed which combines both diffused and concentrated airflow patterns to create a new variable airflow system.

A human body model has been developed for conducting personal computer simulations to evaluate physical work loads, especially muscle loads, associated with the driving position and arm and leg motions. The validity of the model was confirmed by comparing estimated work loads with electromyographic measurements. Correlation analyses were conducted to examine the relationship between the estimated loads and subjective evaluations. The results indicated the regions of the body where loads had the largest impact on the perceived sensation of physical effort and were used to derive an index for evaluating the overall work load of the entire body. The simulation method was used to evaluate control switch positions, driving position and vehicle entry/exit motions.

Research into stability at high speed shows that rear suspension characteristics play an important role in vehicle control and stability. In order to improve the cornering limit steering performance and traction of front-wheel-drive vehicles, where the front wheels bear a large proportion of the load and transmit the driving force, and to maintain vehicle stability when decelerating while cornering, rear suspension characteristics are needed that will fully draw out the cornering force capacity of the rear tires. This requirement continues to grow every year, along with demands for higher levels of comfort in passenger cars, including improved ride quality and quietness. It was against this background that the new multi-link beam rear suspension, which is installed in the new Maxima and Sentra models, was developed. This paper describes the aims, construction, characteristics and effects of this new suspension, with focus on vehicle control and stability.

This paper presents a new electronic torque split four-wheel-drive system called All-Mode 4WD, which has been adopted in the latest generation of sport-utility vehicles (SUVs). As a torque split system designed specifically for SUV use, it provides stable driving performance matching the driver's intentions under all sorts of operating conditions, from a completely natural on-road driving feel to powerful traction for off-road travel.

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.

The authors have developed a steering entropy method to easily and accurately quantify the workload imposed on drivers who are engaged in activities apart from the normal driving operations of longitudinal and lateral control. A driver's steering behavior tends to become more discontinuous while performing an activity in addition to driving. To quantify these discontinuities, steering entropy values are obtained from a time-series history of steering angle data. A special-purpose driving simulator and a test procedure have been developed that allow workload evaluations to be conducted efficiently. The simulator and test procedure were used to evaluate the additional workload incurred by 14 different types of activities. The steering entropy results were compared with a dual task method as well as a subjective evaluation method.

Hypereutectic Al-Si alloy 390, containing large amounts of hard silicon particles, has mainly been used for wear-resistant alloy applications. In the case of hypereutectic Al-Si alloys, the primary silicon particle size and distribution must be controlled to obtain stable wear resistance. The service life of furnaces and molds is shortened by the high melting and casting temperatures required for controlling primary silicon. Furthermore, machinability is degraded by large primary silicon particles. To overcome these problems, a new wear-resistant Al-Si alloy has been developed which provides good castability and machinability. This alloy also has wear resistance and mechanical properties similar to those of the 390 alloy. Specifically, the problems regarding castability and machinability were solved by decreasing the silicon content of the 390 alloy, but that also reduced wear resistance.

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 a computer-controlled power steering system that has been developed and applied to production vehicles. The system provides full power assist at parking speeds, and gradually decreases assistance with increasing vehicle speed to give a normal unassisted “road feel” at highway speeds. The system enables a driver to choose one assistance characteristic among three choices at the flick of a switch, according to the driver's preference and road conditions. A solenoid-operated bypass valve is used to reduce the hydraulic fluid supply to the steering gear, which results in a heavier steering effort. The most suitable valve characteristic curve which corresponds to the increased pressure in the system due to the applied torque is discussed in this study. It is shown that detection of the velocity of steering wheel rotation and extension of the range of characteristics possible are effective ways to ensure good control over the power assistance.

In this study, the functions required of automotive seats were analyzed from the standpoint of occupant posture. The results have been incorporated in the development of the New Generation Ergonomic Seat, which better fits the contours of the human body and prevents a stooped posture that places a greater load on the lumbar region, thereby reducing fatigue during long hours of driving. The new seat adopts the concept of “combined pelvic and lumbar support,” based on an analysis of the muscular and skeletal structure of the human body, sitting posture and body pressure distribution.

Various driver assistance systems have been developed for maintaining a vehicle in its lane. For example, systems that apply force to the steering gear to help the driver keep the vehicle in the center of its lane are becoming popular. On the other hand, direct yaw-moment control systems have been developed for use in stabilizing the vehicle in extremer conditions where loss of control is detected. This paper deals with a system for aiding drivers in recovering from lane departure and maintaining the vehicle in its lane by utilizing direct yaw-moment control. The system uses a CCD camera to recognize lane makers and detects lane departures based on the positional relationship between the vehicle and the lane. When a lane departure is detected, the system applies force to the wheels to generate a yaw moment in the vehicle, so that it turns towards the original lane.

Since the motor vehicle is controlled by the driver, dynamic consideration of the driver-vehicle system is necessary. In this sytem, eye sight is the most important sense with which the driver gets information from the course. In the present research, first, sighting distance in steady straight running was measured by the “slit method”. Next, sighting distance and sighting angle in various curvilinear runnings were measured by use of a “sight point camera” devised by the authors. Introducing the conception of sighting distance and sighting angle, dynamics of the driver-vehicle system is contrived. Theoretical calculation showed that sighting distance should be longer than a certain critical value to make the system stable.

In this study, an attempt was made to apply the steering entropy method, proposed by Boer and Nakayama as a workload measurement technique, to a comparative evaluation of the workload of older and younger drivers. As the first step, driving simulator tests were conducted to examine a method of making comparisons between subjects whose driving performance differed. The same method was then used in making evaluations during driving tests conducted with an actual vehicle. Under the conditions used in this study, the results indicate that it should be possible to compare driving workloads among different subjects through the combined used of Hp and α. Hp is a quantified value of steering perturbation as an information entropy value that is calculated from a time history of steering angle data. It changes between 0 (no steering perturbation) and 1 (absolute randomness) in a theoretical sense.

The purpose of this work was to gain a fundamental understanding of which fuel property parameters are responsible for particulate emission characteristics, associated with key intermediate behavior in the engine cylinder such as the fuel film and insufficient mixing. Accordingly, engine tests were carried out using various fuels having different volatility and chemical compositions under different coolant temperature conditions. In addition, a fundamental spray and film visualization analysis was also conducted using a constant volume vessel, assuming the engine test conditions. As for the physical effects, the test results showed that a low volatility fuel displayed high particulate number (PN) emissions when the injection timing was advanced. The fundamental test clearly showed that the amount of fuel film on the impingement plate increased under such operating conditions with a low volatility fuel.

An important factor in the development of vehicle suspensions has been how to get higher performance from both ride and stability, which are normally in conflict. In addressing this problem, we analyzed the optimum damping forces of shock absorbers for various driving conditions and developed an electronically controlled shock absorber system, which we call “Super Sonic Suspension” based on the results. Through this microcomputer-controlled system, we achieved a great improvement in riding comfort by being able to the damping force much lower than before, based on the results of said analysis. At the same time, stability of the vehicle was also improved by optimumly controlling the damping force for various driving conditions through signals from a newly developed road sensor, which utilizes supersonic waves, and other sensors.

Vehicle roll behavior has a large influence on how drivers evaluate handling performance. This paper describes an approach to quantifying roll behavior experimentally and presents a method for designing suspension properties to improve the sensation of roll. In this study, it was found that using pitch motion as an evaluation index results in good correspondence with subjective evaluations. To obtain acceptable roll behavior, it is important to control pitch motion during roll to a lower mode at the front end relative to the rear. This desirable behavior can be achieved by designing suitable roll center characteristics, nonlinear load changes and damping force coefficients.

On-board voice-interaction systems such as a voice-activated system or a text -to-speech (TTS) system enable drivers to operate devices or to obtain desired information without relying on visual processes. These systems are aimed to reduce the driver's workload, but there is a concern about their possible effect on mental distraction. This paper describes driving simulator tests that were conducted to examine the potential influence of such systems on driver's mental distraction. The results obtained for all of the indices show that the mental distraction level when operating a voice-activated system is significantly lower than that of a traditional manually operated system.

Over the past several decades, vehicle dynamics have been treated mainly on the basis of linear theories. An actual vehicle, however, also shows nonlinear properties such as roll behavior induced by movement of the roll axis. The purpose of this study was to investigate the vehicle roll dynamics in the nonlinear range. Suspensions were divided into two categories and computer-aided engineering (CAE) was used to conduct analyses of complicated kinematics. The results obtained provided theoretical support for designing the Multi-Link Beam Rear Suspension, a new type of suspension for front-wheel-drive cars.