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This paper outlines the most important characteristics of the practical type air bag now being developed by Nissan Motor Co., Ltd. It explains the results of various occupant protection tests conducted at 16 to 64 km/h (10 to 40 mph) speeds, and the related problems we have encountered. It further discusses the effects of several type of occupant protection systems installed on small-sized cars and the relationships between those effects and limited crash speeds. An examination and analysis of air bag performance test results is also included. Despite all efforts made, there yet remain several problems to be solved. For example, (a) in high-speed collisions it is difficult to reduce femur load by means of air bag systems alone; (b) passengers such as three-year-old infants and 5th percentile female adults display a tendency toward submarining: (c) when the environmental temperature is extremely low, it is difficult for the air bag to meet the MVSS Occupant Protection Requirements.

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.

This paper describes a test procedure in which a dummy and a sled impact tester are used to simulate vehicle-pedestrian accidents for the purpose of investigating pedestrian protection. In the series of tests conducted, the bumper height, hood-edge height, bumper lead, front-end compliance of the vehicle, impact velocity, and other factors were varied in an effort to clarify to what extent modifications to the vehicle front end would contribute to enhanced pedestrian protection. Preliminary test findings obtained with this test procedure are also presented regarding the effects of the front-end shape of the vehicle and the stance of the dummy at the moment of impact.

Fatigue tests on a body in white have been made with torsional load and compared with previous results for assessments, where it was difficult to agree with proving ground tests in evaluating the life. Modifying the above mentioned fault, a programmed fatigue test method on the body in white is presented in this paper. The newly developed programmed fatigue test method is the simultaneous loading of the bouncing and torsional modes to a body in while by an electrohydraulic fatigue testing machine in accordance with the programmed sprung mass accelerations. Applying this method, the comparatively accurate assessment of proving ground test was made at the condition of the body in white, and the development period for body construction was shortened.

Japan Automobile Standards Organization (JASO) Engine Oil Sub-committee have been working on the unification of the engine oil evaluation test procedures in Japan. The Engine Oil Sub-committee participated in the recent activity of the worldwide engine oil standardization of SAE and ISO. As one of the chain of activities, JASO tests M328, M331, and M333 (valve train wear, detergency and high temperature oxidation respectively) were conducted on the REOs of ASTM and CEC to find the correlation. The detergency tests (varnish and sludge) showed good correlation with the ASTM REOs. CEC good and poor reference oils seemed to give good results in JASO valve train wear test, while ASTM reference oils unexpectedly gave opposite results in Japanese valve train wear tests.

The ASTM Sequence VE test evaluates lubricant performance for controlling sludge deposits and minimizing overhead camshaft lobe wear. ILSAC asked JAMA to develop a new valve train wear replacement test since the Sequence VE test engine hardware will become obsolete in the year 2000. JAMA submitted the JASO specification M 328-951) KA24E valve train wear test. This first report presents the results of technical studies conducted when JASO M 328-95 was reviewed and the ASTM standardized version of the KA24E test (the Sequence IVA) was proposed. The cam wear mechanism was studied with the goal of improving reproducibility and repeatability. Engine torque was specified to stabilize the NOx concentration in blow-by, which improved test precision. Additionally, the specifications for induction air humidity and temperature, oil temperature control, and test fuel composition were modified when the ASTM version of the KA24E test was proposed.

In recent years, the slip lock-up mechanism has been adopted widely, because of its fuel efficiency and its ability to improve NVH. This necessitates that the automatic transmission fluid (ATF) used in automatic transmissions with slip lock-up clutches requires anti-shudder performance characteristics. The test methods used to evaluate the anti-shudder performance of an ATF can be classified roughly into two types. One is specified to measure whether a μ-V slope of the ATF is positive or negative, the other is the evaluation of the shudder occurrence in the practical vehicle. The former are μ-V property tests from MERCON® V, ATF+4®, and JASO M349-98, the latter is the vehicle test from DEXRON®-III. Additionally, in the evaluation of the μ-V property, there are two tests using the modified SAE No.2 friction machine and the modified low velocity friction apparatus (LVFA).

Finite element models of human body segments have been developed in recent years. Numerical simulation could be helpful when understanding injury mechanisms and to make injury assessments. In the lower leg injury research in NISSAN, a finite element model of the human ankle/foot is under development. The mesh for the bony part was taken from the original model developed by Beaugonin et al., but was revised by adding soft tissue to reproduce realistic responses. Damping effect in a high speed contact was taken into account by modeling skin and fat in the sole of the foot. The plantar aponeurosis tendon was modeled by nonlinear bar elements connecting the phalanges to the calcaneus. The rigid body connection, which was defined at the toe in the original model for simplicity, was removed and the transverse ligaments were added instead in order to bind the metatarsals and the phalanges. These tendons and ligaments were expected to reproduce a realistic response in compression.

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.

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.

Rollover crashes have continued to be a source of extensive research into determining both vehicle performance, and occupant restraint capabilities. Prior research has utilized various test procedures, including the FMVSS 208 dolly fixture, as a basis for evaluating vehicle and restraint performance. This research, using 2001 Nissan Pathfinder sport utility vehicles (SUVs), was conducted to update the status of passenger vehicle rollover testing, and evaluate dynamic test repeatability with a new test procedure. A series of eight rollover tests was conducted using these SUV vehicles, mounted on a modified FMVSS 208 rollover dolly fixture, with instrumented dummies in both front seat positions. This test protocol involved launching the vehicles horizontally, after snubbing the dolly fixture, and having the leading-side tires contact curbing for a trip mechanism.

This paper describes the magnetic circuit design of a coaxial AC motor system, comprising one stator and two rotors, and the test results obtained for a prototype motor. The rotors of the motor share the same stator core and coils, and each rotor uses its magnetic part as a yoke. Magnetic flux linkage of each rotor was determined in consideration of the maximum torque/power conditions and maximum motor speed. Finite Element Method were utilized to design a magnetic circuit for achieving the magnetic flux linkage specification. Tests conducted with a prototype motor showed that the torque characteristics can be divided into magnetic torque and reluctance torque, just like an ordinary IPM motor. Each torque level was improved through field-weakening control. The combined torque obtained when the two rotors were driven simultaneously approximately equaled the sum of the individual torques when the rotors were driven independently.

It is difficult for a conventional robust control algorithm to assure the performance of a slip speed control system, because the plant (lockup system) includes the nonlinear characteristics of the hydraulic system and large changes in the parameters of the slip model at low vehicle speed. The purpose of this study is to reduce the fuel consumption and improve the drivability of vehicles at takeoff by using a slip speed control system. Providing a large feedback gain is effective in reducing the influence of nonlinearity. However, since the operating parameters of the lockup clutch change depending on the driving conditions, that is not possible. A feedback compensator with a gain-scheduled H∞ control method was used in this study to solve these problems. The effectiveness of the slip speed control system was demonstrated in driving tests. Using this control system, the slip speed can be controlled with high accuracy, thereby reducing unnecessary revving of the engine.

The National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety (IIHS) have both developed crash test methodologies to address frontal collisions in which the vehicle's primary front structure is either partially engaged or not engaged at all. IIHS addresses Small Overlap crashes, cases in which the vehicle's primary front energy absorbing structure is not engaged, using a rigid static barrier with an overlap of 25% of the vehicle's width at an impact angle of 0°. The Institute's Moderate Overlap partially engages the vehicle's primary front energy absorbing structure using a deformable static barrier with 40% overlap at a 0° impact angle. The NHTSA has developed two research test methods which use a common moving deformable barrier impacting the vehicle with 20% overlap at a 7° impact angle and 35% overlap at a 15° impact angle respectively.