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A sports car exhibits many challenges from an aerodynamic point of view: drag that limits top speed, lift - or down force - and balance that affects handling, brake cooling and insuring that the heat exchangers have enough air flowing through them under several vehicle speeds and ambient conditions. All of which must be balanced with a sports car styling and esthetic. Since this sports car applies two electric motors to drive front axle and a high-rev V6 turbo charged engine in series with a 9-speed double-clutch transmission and one electric motor to drive rear axle, additional cooling was required, yielding a total of ten air cooled-heat exchangers. It is also a challenge to introduce cooling air into the rear engine room to protect the car under severe thermal conditions. This paper focuses on the cooling and heat resistance concept.

The practical application of heat recovery using thermoelectrics requires the realization of reasonable cost effectiveness. Therefore, a thermoelectric generator (TEG) structure that can compatibly increase efficiency and reduce cost was investigated with the aim of enhancing cost effectiveness. To increase efficiency, a method of using a vacuum space structure to reduce the TEG size was investigated to enable installation just after the close-coupled catalyzer, which is subject to many space restrictions. It was found that by making it possible to use high temperature exhaust heat, power generation efficiency can be increased to approximately twice that of the typical under floor installation. In addition, coupled simulation of heat transfer and power generation using FEM, 1D cost effectiveness simulations, and bench tests were performed with the aim of reducing cost.

Vehicles are required durability in various environments all over the world. Especially water resistance on flooded roads is one of the important issues. To solve this kind of problem, a CFD technology was established in order to predict the water resistance performance of the vehicle at the early development stage. By comparison with vehicle tests on flooded roads, it is clarified the following key factors are required for accurate prediction; the vehicle velocity change, the vehicle height change and the air intake flow rate. Moreover, these three key factors should be appropriately determined from vehicle and engine specification to predict water intrusion for flooded roads at the early stage of development. In this paper, a methodology which determines appropriate analysis conditions mentioned above for flooding simulation from vehicle and engine specification is described. The methodology enables us to determine whether the vehicle provides sufficient waterproofness.

A hybrid simulation model in the transient bench was developed to realize the characteristics of the transient behavior and the fuel economy equivalent to that of a real vehicle. The motors and the batteries that were main components of the hybrid vehicle system were simulated as constructive modules, the functions of which have the integrated control and the input/output (I/O) function with real components. This model enabled us to accommodate a variety of auxiliary (AUX) I/O flexibly. The accuracy of the model was verified by the transient characteristics of the engine and the fuel economy result through correlation with a mass-produced vehicle. Furthermore, the flexibility of the model to a variety of AUX I/O was examined from the simulation test of the vehicle equipped with the waste heat recovery (WHR) system.

A new brake system, able to make efficient use of regenerative braking while maintaining excellent brake feel, has been developed to increase the fuel economy of hybrid vehicles. A hydraulic servo was used as a base to enable mechanical operation of the service brakes; solenoid valves and brake fluid pressure sensors were added to this base to make it possible to control brake line pressure as demanded. The use of a stroke simulator in the hydraulic servo prevents brake feel from being affected by the control of the brake pressure. In addition, high-accuracy brake pressure control that functions cooperatively with the regenerative brakes is enabled, resulting in stable braking effectiveness.

In recent years, the increased use of electric power steering in vehicles has increased the importance of issues such as making systems more compact and lightweight, and dealing with increased development man-hours. To increase development efficiency, the use of a “Hardware in the loop simulator” (HILS) is being tested to shift from the previous development method that relied on a driver's subjective evaluation in an actual vehicle test to bench-test development. Using HILS enables tasks such as specification studies, performance forecasts, issue identification and countermeasure proposals to be performed at an early stage of development even when there is no prototype vehicle. This report describes a case study of using HILS to solve the issues of reducing the load by adjusting the geometric specifications around the kingpin and eliminating the tradeoff by adding a new EPS control algorithm in order to make the electric power steering (EPS) more compact and lightweight.

Improvement of engine cycle thermal efficiency is an effective way to increase engine torque and to reduce fuel consumption simultaneously. However, the extent of the improvement is limited by engine knock, which is more evident at low engine speeds when combustion flame propagation is relatively slow. To prevent engine damage due to knock, the spark ignition timing of a gasoline engine is usually controlled by a knock sensor. Therefore, an engine's ignition timing cannot be set freely to achieve best engine performance and fuel economy. Whether ignition timings for a multi-cylinder engine are the same or can be set differently for each cylinder, it is not desirable for each cylinder has big deviation from the median with respect to knock tendency. It is apparent that effective measures to improve engine knock toughness should address both uniformity of all cylinders of a multi-cylinder engine and improvement of median knock toughness.

The Vehicle Stability Assist (VSA) system can generate sufficient forces to rapidly change the vehicle's motion. We can use this capability to effectively control the vehicle's behavior, but we must pay careful attention to ensure its reliability. The VSA system should be precisely tuned for each vehicle's characteristics in order to satisfactorily control performance without any unnecessary intervention or any excessive warnings. Usually extensive field tests are necessary to precisely tune the VSA system. This paper presents a practical method to tune the VSA system with Hardware-In-the-Loop (HIL) simulations in the final stage of its development. Due to the application of this procedure, both high control capabilities and reliability of the VSA system can be achieved.

A multi-body simulation coupled with a tire model enables the prediction of forces generated on a vehicle when driven over a rough road profile. As the durability of a vehicle depends on these generated forces, the accuracy of the predicted forces is a crucial factor in assessing durability. A new test setup has been used to evaluate the accuracy of the simulation. Due to good reproducibility, the results from physical testing and simulation can be compared in the time domain. This time domain comparison makes it possible to detect any problems associated with the simulation which need to be improved. This new evaluation method is very suitable to full vehicle simulations involving rough road profiles. It was also confirmed that the suspension model with tire model evaluated in this project had an adequate capability for curb strike simulation by a full vehicle.

Lane departure prevention systems are able to detect imminent departure from the road, allowing the driver to apply control to prevent lane departure. These systems possess enormous potential to reduce the number of accidents resulting from road departure, but their effectiveness is highly reliant on their level of acceptance by drivers. The effectiveness of the systems will depend on when they are providing driving assistance, what level of laxness in terms of maintaining contact with the steering wheel is allowed on the part of the driver, and what level of assistance the system provides. This paper will discuss research on the minimum necessary contact and contact strength with the steering wheel on the part of the driver when a lane departure prevention system is in operation.

A multi-use road simulator for reproducing various road loads on motorcycles and buggies has been developed on a test bench by using computer-controlled hydraulic actuators. The device is controlled by a low-priced personal computer and an interface system with custom software. An unique feature is the capability to simulate loads related to such phenomena as the bottoming of suspension and the movement of a telescopic type front fork on the road.

Predicting fuel consumption and performance of an outboard motor for a high speed small planing boat are numerically challenging. The propeller is one of the most popular propulsion systems used for outboard motors. We focused our attention on the fact that the thrust performance of a propeller has a major impact on cruising fuel consumption and performance. We believe that we can numerically predict cruising fuel consumption, which has conventionally been estimated through experiential means, using accurate thrust performance measurements via CFD simulation without cavitations model. This study aims to develop a simulator that could quantitatively predict cruising fuel consumption and performance of an outboard motor used for a high speed small planing boat. After comparing the CFD simulation of propellers against the results of model tests, the simulated results are in good agreement with the experimental results.

A method was designed to predict the gasket surface pressure in consideration of creep which occurs on the surface of the gasket side of the cylinder head in air-cooled engines. Creep caused by heat can cause major deformation on the gasket side of the cylinder head in air-cooled engines, which may result in combustion gas leaking from between the cylinder and cylinder head. Until now, there have been no reports of methods to accurately predict phenomena relating to this deformation in the initial stage of engine design. This study combined values of strain and temperature occurring on the gasket side of the cylinder head, obtained through FEM analysis of steady heat transfer and thermal stress, with unit test results showing the domains in which the influence of the creep is critical or not. This information was used to design a method to determine whether or not an engine's specifications fell into a domain in which creep would have an effect, and predict surface pressure.

Along with the suspension improvement in these two decades, it is well known that the suspension friction force became one of major parameters to affect ride comfort performance. However, it was difficult to carry out quantitative prediction on ride comfort improvement against friction force change with high correlation. It was difficult to analyze correlation between actual vehicle performance and simulation since there were difficulties in controlling damping force and friction individually. On the other hand, magneto-rheological shock absorber (MR Shock) has had several applications and widely spread to passenger vehicles. The large variation and high response of damping force especially in slow piston speed region contributes to achieve an excellent vehicle dynamics performance. However, MR Shock shows the high friction characteristics, due to the unique sliding regime of internal parts. It is said that this high friction characteristic is causing obstacles in ride-comfort.

According to the North American National Automotive Sampling System Crashworthiness Data System (NASS/CDS), approximately one-half of all accidents during driving are of the secondary collision pattern in which the collision event involves the occurrence of secondary collision. Accidents involving impact to a stopped vehicle (chain-reaction collisions) have increased to approximately 3% of all accidents in North America, and although the rate of serious injury is low, cases have been reported of accidents in which cervical sprain occurs as an after-effect[1]. In order to mitigate these circumstances, research has been conducted on systems of automatic braking for collisions. These systems apply brakes automatically when a first collision has been detected in order to avoid or lessen a second collision. Research on automatic collision braking systems, however, has not examined the multiple collisions parked [1, 2].

The aim discussed in this paper is to show a technique to predict loads input to the wheels, essential to determining input conditions for evaluation of suspension durability, by means of full vehicle simulations using multi body analysis software Adams/Car. In this process, model environments were built to enable reproduction of driving modes, and a method of reproducing the set-up conditions of a durability test vehicle was developed. As the result of verification of the accuracy of the simulations in the target driving modes, good correlation for waveforms can be confirmed. And also confirm a good correlation in relation to changes of input load due to changes in suspension specifications.

The change in the aerodynamic lift force (henceforth CL) by heave motion is discussed in this paper in order to clarify the effect of aerodynamic characteristics on the vehicle dynamic performance. We considered that phenomenon in actual car running at 160km/h and 1Hz heave frequency. Using a towing tank to change its water from the air to the working fluid to more easily observe this phenomenon. That makes possible to observe the same phenomenon with reduced velocity and small models under same Strouhal number condition. This method can be reducing vehicle speed to 3m/s (1/15 actual) and frequency to 0.2Hz (1/5 actual) in case using 40% scaled model. The results of these tests showed that unsteady CL is proportional to heave motion. These results showed the proportional relationship between unsteady CL and heave motion. The formularization of unsteady CL made it possible to introduce shape coefficients to vehicle dynamics simulations as functions of heave velocity.

Car engine piston cooling is an important technology for improving the compression ratio and suppressing the deformation of pistons. It is well known that thermal conductivity improves dramatically through the use of heat pipes in computers and air conditioners. However, the heat pipes in general use have not been used for the cooling of engines because the flow of gas and liquid is disturbed by vibration and the thermal conductivity becomes excessively low. We therefore developed an original heat pipe and conducted an experiment to determine its heat transfer coefficient using a high-speed reciprocation testing apparatus. Although the test was based on a single heat pipe unit, we succeeded in improving the heat transfer coefficient during high-speed reciprocation by a factor of 1.6 compared to the heat transfer coefficient at standstill. This report describes the observed characteristics and the method of verification.

The cooling performance and the heat resistance performance of commercial vehicle are balanced with aerodynamic performance, output power of powertrain, styling, cost and many other parameters. Therefore, it is desired to predict the cooling performance and the heat resistance performance with high accuracy at the early stage of development. Among the three basic forms of heat transfer (conduction, convection and radiation), solving thermal conduction accurately is difficult, because modeling of “correct shape” and setting of coefficient of thermal conductivity for each material need many of time and efforts at the early stage of development. Correct shape means that each part should be attached correctly to generate the solid mesh with high quality. Therefore, it is more efficient and realistic method to predict the air temperature distribution around the rubber/resin part instead of using the surface temperature at the preliminary design stage.

In motorcycles, the mass difference between a vehicle and a rider is small and motions of a rider impose a great influence on the vehicle behaviors as a consequence. Therefore, dynamic properties of motorcycles should be evaluated not merely dealing with a vehicle but considering with a man-machine system. In the studies of a simulation for vehicle dynamics, various types of rider models have been proposed and it has already been reported that rider motions have a significant influence on the dynamic properties. However, the mechanism of the interaction between a rider and a vehicle has not been clarified yet. In our study, we focused on weave motion and constructed a full vehicle simulation model that can reflect the influences of the movements of the rider’s upper body and lower body. To construct the rider model, we first measured the vibrational characteristics of a human body using a vibration test bench.