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This paper presents a vehicle dynamic simulation using a finite element method for performing more accurate simulations under extreme operating conditions with large tire deformation. A new hourglass control scheme implemented in an explicit finite element analysis code LS-DYNA(1) is used to stabilize tire deformation. The tires and suspension systems are fully modeled using finite elements and are connected to a rigid body that represents the whole vehicle body as well as the engine, drive train system and all other interior parts. This model is used to perform cornering and braking behavior simulations and the results are compared with experimental data. In the cornering behavior simulation, the calculated lateral acceleration and yaw rate at the vehicle's center of gravity agree well with the experimental results. Their nonlinear behavior is also well expressed.

This paper describes a system for measuring unsteady pressure at up to 256 spatial points and at frequencies up to 300 Hz. The system consists of commercially available equipment for measuring steady pressures. It is based on the use of electronically scanned pressure (ESP) sensors, 16 A/D converters, and a personal computer to control the whole system and acquire data. The signal outputs through the tubes connecting the pressure taps and the ESP sensors are compensated, as are the phase delays between the scanned signals and the gain variation. A 1/5 scale model of a sedan was used in this experiment. The passenger car model was placed in a wind tunnel equipped with a moving belt, which was operated at the same speed as the uniform flow in the wind tunnel. Pressure measurements were obtained at 252 points in a plane behind the model perpendicular to the uniform flow. Measurements were made with the belt turned on and off.

This paper describes the development of a vehicle with four-wheel steering in which the rear wheels can be controlled electronically in addition to the conventional front-wheel steering system. In the method for steering the rear wheels, the side-slip angle at the vehicle's center of gravity is maintained at zero, which improves the basic dynamic properties of the vehicle. This approach allows greater maneuverability at low speed by means of counter-phase rear steering and improved stability at high speed through same-phase rear steering. However, the use of counter-phase rear steering to improve maneuverability gives rise to problems in regard to practicality. In addition, continuously controlled four-wheel steering, using counter-phase at low speed and same-phase at high speed, leads to many other problems regarding practicality because of the strong apparent understeer characteristics.

The demands on valve seat insert materials, in terms of providing greater wear-resistance at higher temperatures, enhanced machinability and using non-environmentally hazardous materials at a reasonably low cost have intensified in recent years. Due therefore to these strong demands in the market, research was made into the possibility of producing a new valve seat insert material. As a result a high speed steel based new improved material was developed, which satisfies the necessary required demands and the evaluation trials, using actual gasoline engine endurance tests, were found to be very successful.

Electric Vehicle distinctive techniques in order to enhance the vehicle dynamic performance have been studied and applied to Nissan LEAF. From the viewpoint of performance design parameters, this paper introduces the application items focusing on effectuality for the vehicle behavior by means of the yawing motion and the rolling motion control of its vehicle. As the result, the effects of vehicle performance are shown in experimental data.

Although automotive electronics was initially applied as a substitute for mechanical parts, this technology has the potential to achieve effective combinations of mechanical functions. A case in point is the successful resolution of fuel consumption and exhaust emission problems by effectively integrating engine control and catalyst technologies. LSI technology has also been incorporated into automotive electronics and established as a fundamental engine control tool. Thanks to LSI technology, particularly the use of microprocessor techniques, conventional machine design problems have been transformed into logical design ones. In the next stage of application, automotive electronics is expected to provide further benefits including a more comfortable ride, an improved human-machine system interface, and an advanced communications system between vehicles and other telecommunications stations.

This paper describes the numerical and experimental approaches that were applied to study swirl injectors that are widely used in direct-injection gasoline engines. As the numerical approach, the fuel and air flow inside an injector was first analyzed by using a two-phase flow analysis method [VOF (Volume of Fluid) model]. A time-series analysis was made of the flow though the injector and also of the air cavity that forms at the nozzle and influences fuel atomization. The calculated results made clear the process from initial spray formation to liquid film formation. Spray droplet formation was then analyzed with the synthesized spheroid particle (SSP) method. As the experimental approach, in order to measure the cavity factor that represents the liquid film thickness, nozzle exit flow velocities were measured by particle image velocimetry (PIV).

This paper presents a swiring flow type jet pump which has been developed and in put into practical use in transferring fuel between sumps in saddle-shaped fuel tanks. The pump is driven by the force of excess fuel returning from the engine. The major structural features of the pump are described along with its performance. Various problems encountered in the process of developing the pump are discussed along with the technologies developed to resolve them. Particular attention is focused on the effects that the geometries if the nozzle, throat and swirling groove have on fuel transfer efficiency. The results of experiments carried out to analyze these correlations are also presented.

Since a 4-valve engine is less flexible in the design and location of the intake ports as compared with a conventional 2-valve engine, there are some difficulties in strengthening the air motion, including swirl and turbulence, in order to achieve stable combustion under lean mixture operation. This study examined air motion imporvements of 4-valve engine that result in a stable combustion with a lean mixture. These improvements are brought about by the installation of a swirl control valve in each intake port. The results of this study have clarified that the lean stable limit was extended from an air-fuel ratio of 21.5 to 26.3 under a partial load, by optimizing the location and diameter of aperture of the swirl control valve.

The key-points in the diffusion bonding technique of green compacts during sintering, are the material compositions, which should be chosen according to their dimensional change during sintering, and the fitting clearance, which should be maintained in the range of press fit. Applying this technique, we have developed sinter-diffusion bonded idler sprockets for automotive engines by comfirming the bonding strength and torsional fatigue strength. And we also have developed a nondestructive analysis method for assuring the joint strength of idler sprockets in the mass production.

This paper describes simultaneous attainment in improving fuel consumption, output power and reducing HC emissions with a direct injection S.I. engine newly developed in Nissan. Straight intake port is adopted to increase discharge coefficient under WOT operation and horizontal swirl flow is generated by a swirl control valve to provide stable stratified charge combustion under part load conditions. As a result, fuel consumption is reduced by more than 20% and power output is improved by approximately 10%. Moreover, unburned HC is reduced by equivalently 30% in engine cold start condition. An application of diagnostic and numerical simulation tools to investigate and optimize various factors are also introduced.

This paper reports attempts to gain better understanding of the influence of bearing wear on the performance of hydrodynamically lubricated bearings. An analysis was carried out on bearings from a Sapphire bearing test rig using an elastohydrodynamic model. This involved the use of both the original and worn bearing surface profiles. The results indicated that bearing wear could improve the lubrication conditions. Also the progress of wear in the bearing was simulated using a simple model of the wear process. This model predicted that the wear would progress at a reducing rate. The predicted wear agreed well with measurements both in terms of the wear profile and the location of wear.

A variable swirl intake port system for 4 valves/cylinder direct injection diesel engines was developed. This system combines two mutually independent intake ports, one of which is a helical port for generating an ultra-high swirl ratio and the other is a tangential port for generating a low swirl ratio. The tangential port incorporates a swirl control valve that controls the swirl ratio by varying the flow rate. To investigate the performance of the intake port system, steady-state flow tests were conducted in parallel with three-dimensional computations. In conducting the steady-state flow tests, it was found that a paddle wheel flow sensor was not suitable for evaluating the characteristics of the high-swirl port and that it was necessary to use an impulse swirl flow meter.

Achieving a multi-cylinder engine with excellent noise/vibration character sties and low friction at the main bearings requires an optimal design not only for the crankshaft construction but also for the bearing support system of the cylinder block. To accomplish that, it is necessary to understand crankshaft system behavior and the bearing load distribution for each of the main bearings. Crankshaft system behavior has traditionally been evaluated experimentally because of the difficulty in performing calculations to predict resonance behavior over the entire engine speed range. A coupled crankshaft-block analysis method has been developed to calculate crankshaft system behavior by treating vibration and lubrication in a systematic manner. This method has the feature that the coupled behavior of the crankshaft and the cylinder block is analyzed by means of main bearing lubrication calculations. This paper presents the results obtained with this method.

As the quietness of vehicles has been continually improved in recent years, there have been stronger requirements to reduce transmission gear noise and thereby improve transmission quality. So far efforts to achieve quieter gears have generally focused on ways of reducing the excitation forces of individual gears. In addition to these traditional methods, there is a greater need today to adopt a new approach to gear noise reduction in which improvements are made to the gear train itself as the transmitter of vibration in the transmission. This paper describes the systematic approach taken to reduce the overall gear noise of the new RE4F04A four-speed automatic transaxle.The cross-sectional view is shown in Fig. 1. The vibration characteristics of this automatic transaxle were first identified by finite element analysis, and an investigation was made of a gear train structure that would be effective in reducing gear noise.

Improving the durability and reliability of crankshaft bearings has become an important issue for automotive engines recently because of conflicting demands for lower fuel consumption and higher power output. This study focused on the connecting rod big-end bearing which is subjected to harsher operating conditions on account of these requirements. It is known that the crank pin journal temperature is an indicator of big-end bearing seizure. Having a simple method for predicting the crank pin journal temperature with the required accuracy at the design stage is indispensable to efficient engine development. In this study, analyses were first conducted to determine the oil flow rate at the big-end bearing which is a major determinant of the crank pin journal temperature.

In October 1985, a new wind tunnel was completed and put into operation at the Nissan Technical Center. This paper describes its main specifications and performance features, and gives results of a number of experiments using the new facility. It is a closed-circuit wind tunnel of the so-called Göttingen type, with a semi-open test section. The test section is equipped with two different nozzles, which are used interchangeably depending on the type of testing being carried out. The larger nozzle has a maximum wind velocity of 190 kmh, and a cross-section 4 m high by 7 m wide. The other is 3 m high by 5 m wide and has a maximum wind velocity of 270 kmh. All of the testing equipment in the tunnel, including the axial-flow fan, six-component aerodynamic balance, and traverse system, are operated automatically by a control system made up of several computers linked together. The most notable feature of this wind tunnel is the large reduction that has been made in background noise.

Internal combustion engines experience severe valve train wear and the reduction of valve seat and seat insert wear has been a long-standing issue. In this work, worn valve seats and inserts were examined to obtain a fundamental understanding of the wear mechanisms and the results were applied in developing new valve seat insert materials. The new exhaust valve insert material for gasoline engines is a sintered alloy steel containing Co-base hard particles, with lead infiltrated only for inserts used in unleaded gasoline engines. The new intake valve insert material for gasoline engines is a high-Mo sintered steel, obtained through transient liquid phase sintering and with copper precipitated uniformly. This material can be used for both leaded and unleaded gasoline engines. Valve and valve seat insert wear has long been an issue of concern to engine designers and manufacturers.

A CVT variator chain system is superior in transmission efficiency to a belt system because of its lower internal friction. However, a chain produces more noise than a belt due to the long pitch length of contact between the pulleys and rocker pins. This study focuses on optimization of the pitch sequence for reducing chain noise. The previous pitch sequence was suitably combined of links of different lengths to improve noise dispersibility for reducing chain noise. First, the object function was defined as the reduction of the peak level of 1st-order chain noise combined with a well-balanced the levels on the low and high frequency sides. Interior background noise consisting of road noise and wind noise have the characteristic that they increase as the frequency decreases.

A copper alloy powder composed of Cu-14Ni-3Si-2V-2Cr-1.5Fe-1Al-0.5P has been developed for application to laser-clad valve seats. Laser-clad valve seats offer several advantages such as higher engine output and improved fuel economy owing to lower valve head temperature and an increased intake throat diameter compared with conventional press-fit valve inserts made of ferro-based powder metal. Previously, a material having a principal chemical composition of Cu-12Ni-10Co-3Si-2V-2Nb-1.5Fe-1Al was developed to obtain large hard intermetallic compounds. The microstructure of this material is formed by a two-liquid separation reaction, which has been applied to powders of different chemical compositions for laser-clad valve seats of production engines. Although this material shows superior valve seat wear resistance, it has certain drawbacks, including the high cost of the powder, high probability of microcrack formation and low machinability of the laser-clad layer.