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This study examined a method of predicting the piston temperature in reciprocating internal combustion engines with the aim of developing lightweight pistons. Since the piston temperature is strongly affected by the in-cylinder temperature distribution and turbulence, it is necessary to consider the effects of flame propagation, cooling by the intake air, temperature rise due to combustion, in-cylinder flow and the combustion chamber shape. A three-dimensional combustion simulation that can take these effects into consideration was run to calculate the heat transfer coefficient from the piston crown surface and the gas temperature. The results were used as the boundary conditions for an analysis of heat transfer from the piston, and a method was thus developed for analyzing the piston temperature.

A vehicle sometimes pulls to one side during traveling straight. This is caused by lateral disturbance, such as road contour, suspension alignment error and tire properties. This paper describes a new algorithm of reducing steering pull by using electric power steering system(EPS). It is shown that the disturbance can be cancelled with EPS motor torque. The amount of the torque is equal to the steady driver's torque to keep the vehicle straight driving. It is estimated by using statistic method. We validate our study by driving test conducted with an actual vehicle.

Vehicle's dynamic pre-crash state and associated occupant motion may influence the damage and injury of traffic accidents. Therefore it is important to simulate phenomena before and after impact continuously in order to analyze the damage mechanisms of traffic accidents. In this study, a finite element vehicle model that can simulate both running and crash is developed and verified by some experimental results, and the methods to speed up and stabilize computation that enable continuous simulation are developed and compared with conventional methods. A numerical example that simulates a real traffic accident situation is also shown.

With SUVs and minivans accounting for a larger share of the US market in the past decade, rollover accidents have drawn greater attention, leading to more active research from different perspectives. This ranges from investigations for elucidating the basic causes and mechanisms of rollover accidents to studies of more advanced occupant protection measures. As the phenomenon of a rollover accident is longer in duration than frontal, side or rear impacts, it is relatively difficult [1] to simulate such accidents for experimental verification and also for proper evaluation of occupant restraint system performance. In this work, we focused on the trip-over type, which occurs most frequently, and performed simulations to reproduce real-world rollover accidents by combining PC-Crash and FEA. Soil trip-over simulation was carried out based on real world accidents.

It is important to estimate the vehicle state accurately in order to control vehicle behavior. In this study, we used the vehicle sideslip angle as a value indicating vehicle instability. A new method was developed that can estimate the sideslip angle accurately without being affected by driving conditions. This paper describes this new method and presents the results of evaluation tests that demonstrate its effectiveness.

In a frontal automotive crash, the driver's foot is usually stepping on the brake pedal as an instinctive response to avoid a collision. The tensile force generated in the Achilles tendon produces a compressive preload on the tibia. If there is intrusion of the toe board after the crash, an additional external force is applied to the driver's foot. A series of dynamic impact tests using human cadaveric specimens was conducted to investigate the combined effect of muscle preloading and external force. A constant tendon force was applied to the calcaneus while an external impact force was applied to the forefoot by a rigid pendulum. Preloading the tibia significantly increased the tibial axial force and the combination of these forces resulted in five tibial pylon fractures out of sixteen specimens.

It can be said that super sports car has a mission to drive the evolution of cars with optimizing the balance between power and environmental performances and pursuing the ultimate driving performance. Nissan has therefore developed the brand new V6 gasoline twin-turbocharged engine for a new generation of super sports cars. To achieve high environmental as well as high dynamic performance, the V6-cylinder layout was selected for its compact size and lightweight while the twin-turbocharged design was aiming for downsizing. All engine parts were designed to achieve high efficiency, as for example, the plasma-sprayed coating of the bore which improves greatly the cooling performance, or the super-heat resistant steel used for the turbocharger, which improves combustion efficiency. Thanks to this technological advance, top-level properties could be attained for sports cars in terms of fuel economy and emissions.

A finite element human model has been developed to simulate occupant behavior and to estimate injuries in real-world car crashes. The model represents an average adult male of the US population in a driving posture. Physical geometry, mechanical characteristics and joint structures were replicated as precise as possible. The total number of nodes and materials is around 67,000 and 1,000 respectively. Each part of the model was not only validated against human test data in the literature but also for realistic loading conditions. Additional tests were newly conducted to reproduce realistic loading to human subjects. A data set obtained in human volunteer tests was used for validating the neck part. The head-neck kinematics and responses in low-speed rear impacts were compared between the measured and calculated results. The validity of the lower extremity part was examined by comparing the tibia force in a foot impact between the test data and simulation results.

A new variable valve actuation system that varies valve lift and timing events continuously has been devised and confirmed to substantially improve power and reduce fuel consumption when applied to a SI engine. The variable valve event and lift (VEL) system is a simple mechanism consisting of oscillating cams and linkages, enabling it to operate the valves smoothly even at high speed. Its compact size facilitates application to direct-acting valve trains and its ability to vary valve lift from a deactivated state (0) to a large lift amount allows the system to be used with a wide range of engine concepts. In this study, VEL was combined with a phase shifting function to enable the valve lift characteristic to be varied virtually arbitrarily, and test results showed that fuel consumption of a SI engine was reduced by nearly 10%.

Vehicle service loads need to be measured under actual driving conditions in order to ascertain the strength and durability requirements for customer usage. However, because road-load data are influenced by the vehicle category and specifications of a vehicle, it takes an enormous amount of time and labor to compare them with existing data and analyze the relationship between service loads and vehicle specifications. This paper presents a study concerning the use of the frequency response function, which differs from one vehicle to another, as a means of predicting the response of a particular target vehicle based on the road-load data, which are input by unevenness of roads, measured for a baseline vehicle. The results predicted in bench tests showed a margin of error of around ±20%, making them sufficiently accurate for practical use. Rice's formula was applied as an index for evaluating the prediction accuracy of the power spectral density.

Incompatibility between two colliding cars is becoming an important issue in passive safety engineering. Among various phenomena, indicating signs of incompatibility, over-riding and under-riding are likely caused by geometrical incompatibility in vertical direction. The issue of over-riding and under-riding is, therefore, not only a problem for partner-protection but also a possible disadvantage in self-protection. One of the possible solutions of this dual contradictory problem is to have a good structural interaction between the front-ends of two cars. Studies have been done to develop a test protocol for assessment of this interaction and to define criteria for evaluation but mostly in terms of aggressivity, which is a term describing incompatibility of a relatively stronger car. In this study, it was hypothesized that homogeneous front-end could be a possible better solution for good structural interaction.

This paper presents the numerical simulations of a headform impact on hoods and front-end structures. Finite Element (FE) modelling of the headform impactor and the engine compartment are described. An explicit FE code PAM CRASH™ is used to predict the time history of the acceleration of the headform. Several numerical examples are presented to demonstrate the effectiveness of this simulation. Additionally, parameter studies are conducted to evaluate the accuracy of the test results and evaluate the design parameters. Although additional study is needed, good correlation at the majority of the evaluating points was achieved.

Improving the robustness of vehicle crashworthiness in relation to the impact angle may be quite important in enhancing vehicle safety under actual driving conditions. This importance can also be inferred from the fact that almost all of the accidents classified as frontal crashes in real-world driving have an impact angle. The first step of this research was to make clear the differences between inline offset impacts and oblique offset impacts, focusing on the behavior of the vehicle. Based on the results obtained, a feasibility study for improving the robustness of vehicle crashworthiness relative to the impact angle in frontal collisions was carried out. In order to analyze vehicle behavior and examine ways of improving robustness, oblique offset car-to-car (CTC) impact tests were conducted and simulations were run using finite element (FE) models. The method of evaluating vehicle body strength that was reported by Kitagawa et al. [7] was utilized to process the data.

This paper presents a variable compression ratio (VCR) system that has a new piston-crankshaft mechanism with multiple links. This multi-link mechanism varies the piston position at top dead center (TDC), making it possible to change the compression ratio of the engine continuously. Previous attempts have been made to achieve variable compression ratio with this type of method, but it was difficult to avoid various undesirable effects such as an increase in the engine size, substantial weight increases, increased engine block vibration due to a worsening of piston acceleration characteristics and increased friction resulting from a larger number of sliding parts. At the stage of developing the basic design of the multi-link geometry, emphasis was placed on selection of a suitable link geometry and optimization of the detailed dimensions with the aim of essentially resolving these previous issues.

On one hand automotive manufacturers are trying to reduce product development times, while on the other hand they are aiming to bring more products to the market. Since safely and reliability must always be guaranteed, they use CAE to achieve this. For calculating road loads accurately, the tire and road model are key components of the CAE model. TNO has developed the MF-Swift tire model, which is a Magic Formula based rigid ring model. In combination with its enveloping model, MF-Swift can be used to simulate the tire dynamic response to arbitrary road unevenness. MF-Swift is aimed to be an all-encompassing tire model that can be used for handling, ride comfort and durability applications. Since it is based on Pacejka's Magic Formula, its application for handling events is well-known. Recently the OpenCRG road format has been released which makes it possible to describe large pieces of digitized 3D road surfaces in a uniform and efficient way.

The bores of the cylinder block are usually machined prior to assembly with the cylinder head. In this case, bore distortion occurs when the cylinder block is assembled with the cylinder head due to the load applied by the head bolts and the surface pressure of the head gasket. This bore distortion influences sealing and operating characteristics of the pistons and piston rings, requiring an increase in bore thickness and addition of ribs to obtain higher cylinder block rigidity, which lead to an increase in weight. In order to improve engine performance, it is necessary to control bore distortion more effectively. With the aim of reducing bore distortion when assembled with the cylinder head, the bores are machined with a dummy cylinder head installed on the block to provide an equivalent head bolt load and gasket surface pressure. By using this bore circulatory machining technology, bore distortion after cylinder head assembly can be reliably suppressed.

Hot fuel handling is becoming a more important factor for passenger car driveability because of the trends toward increased gasoline volatility and higher fuel temperature in the engine comportment. However, passenger car development work is very short term and vehicles under development are used under a variety of conditions, employ several types of fuel supply systems and exhibit different fuel supply pressures. Therefore, it is necessary to find a index that can expect the hot fuel handling performance for use in passenger car development work. This report describes the results of tests carried out to find a new index called the fuel handling index. These tests were performed under using passenger cars with different types of fuel supply systems and pressures, different temperatures, using gasolines of different volatility and under different driving conditions.

Accurate measurements of combustion gas temperature and the coefficient of heat transfer between the gas and the combustion chamber wall of internal combustion engine in cyclic operations are difficult at present. Hence the only method available for determination of states of thermal load and heat loss to the combustion chamber wall in a cycle is to measure the instantaneous temperature on the combustion chamber wall surface accurately and precisely using proper thin-film thermocouples, then to calculate the instantanenous heat flux flowing into the wall surface by means of numerical analysis. However, it is necessary to pay adequate attention to the effects of thermophysical properties of the thermocouple materials on the measured values, since any thermocouple consists of several kinds of materials which are different from those of portions to be measured.

In a CTC (car to car) crash, interaction between two vehicles is quite important. Interaction is primarily described by the contact area between two vehicles but interaction force (impact force) is also important for the entire crash phenomenon. In a frontal crash, impact force is resisted by the body structures, engine block, and tires. The resultant share of energy absorption, as well as the magnitude of body deformation, is greatly affected by the force profile. It is desired, therefore, to evaluate those factors of vehicle bodies in order to achieve CTC compatibility. There are some technical obstacles, however, in measuring those factors in testing. Impact force, for instance, cannot be measured directly in a CTC crash test unless load cells are installed in body frames. It is also difficult to analyze body deformation in a CTC crash test because both vehicles are moving.