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Technical Paper

Summary report of Japan Clean Air Program diesel and diesel fuel activities

2007-07-23
2007-01-1952
Diesel emissions are significant issue worldwide, and emissions requirements have become so tough that. the application of after-treatment systems is now indispensable in many countries To meet even more stringent future emissions requirements, it has become apparent that the improvement of market fuel quality is essential as well as the development in engine and exhaust after-treatment technology. Japan Clean Air Program II (JCAP II) is being conducted to assess the direction of future technologies through the evaluation of current automobile and fuel technologies and consequently to realize near zero emissions and carbon dioxide (CO2) emission reduction. In this program, effects of fuel properties on the performance of diesel engines and a vehicle equipped with two types of diesel NOx emission after-treatment devices, a Urea-SCR system and a NOx storage reduction (NSR) catalyst system, were examined.
Technical Paper

Research on a brake assist system with a preview function

2001-06-04
2001-06-0209
Traffic accidents in Japan claim some 10,000 precious lives every year, and there is seemingly no end to the problem. In an effort to overcome this situation, vehicle manufacturers have been pushing ahead with the development of a variety of advanced safety technologies. Joint public- private sector projects related to Intelligent Transport Systems (ITS) are also proceeding vigorously. Most accidents can be attributed to driver error in recognition, judgment or vehicle operation. This paper presents an analysis of driver behavior characteristics in emergency situations that lead to an accident, focusing in particular on operation of the brake pedal. Based on the insights gained so far, we have developed a Brake Assist System with a Preview Function (BAP) designed to prevent accidents by helping drivers with braking actions. Experimental results have confirmed that BAP is effective in reducing the impact speed and the frequency of accidents in emergency situations.
Technical Paper

Compact and Long-Stroke Multiple-Link VCR Engine Mechanism

2007-10-29
2007-01-3991
A multiple-link variable compression ratio (VCR) mechanism is suitable for a long-stroke engine by providing the following characteristics: (1) a nearly symmetric piston stroke and (2) an upper link that stays vertical around the time of the maximum combustion pressure. These two characteristics work to reduce force inputs to the piston. The maximum inertial force around top dead center is reduced by the effect of the first characteristic. The second characteristic is effective in reducing piston side thrust force and helps ease piston pin lubrication. Because of the combined effect of these characteristics, the piston skirt can be made smaller and the piston pin can be shortened. That makes it possible for the piston skirt and piston pin to move between the counterweights, resulting in a downward extension of the piston stroke. As a result, a longer-stroke engine mechanism can be achieved without making the cylinder block taller.
Technical Paper

The Effect of a Longer Stroke on Improving Fuel Economy of a Multiple-Link VCR Engine

2007-10-29
2007-01-4004
Some automakers have been studying variable compression ratio (VCR) technology as one possible way of improving fuel economy. In previous studies, we have developed a VCR mechanism of a unique multiple-link configuration that achieves a piston stroke characterized by semi-sinusoidal oscillation and lower piston acceleration at top dead center than on conventional mechanisms. By controlling compression ratio with this multiple-link VCR mechanism so that it optimally matches any operating condition, the mechanism has demonstrated that both lower fuel consumption and higher output power are simultaneously possible. However, it has also been observed that fuel consumption does not reduce further once the compression ratio reached a certain level. This study focused on the fact that the piston-stroke characteristic obtained with the multiple-link mechanism is suitable to a longer stroke.
Technical Paper

Analysis of Rollover Restraint Performance With and Without Seat Belt Pretensioner at Vehicle Trip

2002-03-04
2002-01-0941
Eight rollover research tests were conducted using the 2001 Nissan Pathfinder with a modified FMVSS 208 dolly rollover test method where the driver and right front dummy restraint performance was analyzed. The rollover tests were initiated with the vehicle horizontal, not at a roll angle. After the vehicle translated laterally for a short distance, a trip mechanism was introduced to overturn the vehicle. Retractor, buckle, and latch plate performance in addition to the overall seat belt performance was analyzed and evaluated in the rollover test series. Retractor pretensioners were activated near the rollover trip in three of the tests to provide research data on its effects. Various dummy sizes were utilized. The test series experienced incomplete data collection and a portion of the analog data was not obtained. National Automotive Sampling System (NASS) data was also analyzed to quantify the characteristics of real world rollovers and demonstrated the benefits of restraint use.
Technical Paper

Design of Lane-Keeping Control with Steering Torque Input for a Lane-Keeping Support System

2001-03-05
2001-01-0480
This paper describes the method used to design the basic control algorithm of a lane-keeping support system that is intended to assist the driver's steering action. Lane-keeping control has been designed with steering torque as the control input without providing a minor loop for the steering angle. This approach was taken in order to achieve an optimum balance of lane-keeping control, ease of steering intervention by the driver and robustness. The servo control system was designed on the basis of H2 control theory. Robustness against disturbances, vehicle nonlinearity and parameter variation was confirmed by μ - analysis. The results of computer simulations and driving tests have confirmed that the control system designed with this method provides the intended performance.
Technical Paper

Development of Nissan's New Generation 4-Cylinder Engine

2001-03-05
2001-01-0328
This paper describes the new inline 4-cylinder QR engine series that is available in 2.0-liter and 2.5-liter versions. The next-generation QR engine series incorporates new and improved technologies to provide an optimum balance of power, quietness and fuel economy. Its quiet operation results from the adoption of a compact balancer system and the reduced weight of major moving parts. Power and fuel economy have been enhanced by a two-stage cooling system, a continuous variable valve timing control system, a dual close coupled catalyst system, electronic throttle control and an improved direct-injection system. The latter includes an improved combustion chamber concept and improved fuel spray characteristics achieved by driving the injector by battery voltage. A lightweight and compact engine design has been achieved by adopting a high-pressure die cast aluminum cylinder block, resin intake manifold and rocker cover and a serpentine belt drive.
Technical Paper

JamaS Study on the Location of In-Vehicle Displays

2000-11-01
2000-01-C010
JAMA (Japan Automobile Manufactures Association, Inc.)'s guideline for car navigation systems is being decided on displayed the amount of information while driving. The position of a display and the estimated equation, which could be applied from a passenger car to a heavy truck, was studied. The evaluation index was the distance which drivers could become aware of a preceding vehicle by their peripheral vision, because car accidents while drivers glance at an in- vehicle display are almost the rear end collisions. As the results, the lower limit of a position of an in-vehicle display for a passenger car was 30 degrees, and a heavy truck was 46 degrees.
Technical Paper

Intelligent Sensing System to Infer DriverS Intention

2000-11-01
2000-01-C056
An approach to designing an intelligent vehicle controller for partially supporting driver operation of a vehicle is proposed. Vehicle behavior is regarded as a system performed by the interaction between the driving environment, vehicle as a machine and driver expectations for the vehicle movements. Driver intention to accelerate or decelerate is mainly generated by the perception of the driving environment. The model we propose involves information on the driving environment affecting driver intention taking driver differences in perceiving the driving environment into account. An engineering model for installing the vehicle controller is expressed by a multipurpose decision-maker allowing explicit treatment of the driving environment, vehicle action, and driver intention. A reasoning engine deals with differences in individual driver traits for generating intention to decelerate by using fuzzy integrals and fuzzy measures.
Technical Paper

Research on a Brake Assist System with a Preview Function

2001-03-05
2001-01-0357
Traffic accidents in Japan claim some 10,000 precious lives every year, and there is seemingly no end to the problem. In an effort to overcome this situation, vehicle manufacturers have been pushing ahead with the development of a variety of advanced safety technologies. Joint public-private sector projects related to Intelligent Transport Systems (ITS) are also proceeding vigorously. Most accidents can be attributed to driver error in recognition, judgment or vehicle operation. This paper presents an analysis of driver behavior characteristics in emergency situations that lead to an accident, focusing in particular on operation of the brake pedal. Based on the insights gained so far, we have developed a Brake Assist System with a Preview Function (BAP) designed to prevent accidents by helping drivers with braking actions. Experimental results have confirmed that BAP is effective in reducing the impact speed and the frequency of accidents in emergency situations.
Technical Paper

Development of an Adaptive Cruise Control System with Stop-and-Go Capability

2001-03-05
2001-01-0798
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.
Technical Paper

Finite Element Analysis of Hard and Soft Tissue Contributions to Thoracic Response: Sensitivity Analysis of Fluctuations in Boundary Conditions

2006-11-06
2006-22-0008
Thoracic trauma is the principle causative factor in 30% of road traffic deaths. Researchers have developed force-deflection corridors of the thorax for various loading conditions in order to elucidate injury mechanisms and to validate the mechanical response of ATDs and numerical human models. A corridor, rather than a single response characteristic, results from the variability inherent in biological experimentation. This response variability is caused by both intrinsic and extrinsic factors. The intrinsic factors are associated with individual differences among human subjects, e.g., the differences in material properties and in body geometry. The extrinsic sources of variability include fluctuations in the loading and supporting conditions in experimental tests.
Technical Paper

Effects of Fuel Properties on the Performance of Advanced Diesel NOx Aftertreatment Devices

2006-10-16
2006-01-3443
In the Japan Clean Air Program II (JCAP II) Diesel WG, effects of fuel properties on the performance of two types of diesel NOx emission aftertreatment devices, a Urea-SCR system and a NOx storage reduction (NSR) catalyst system, were examined. For a Urea-SCR system, the NOx emission reduction performance with and without an oxidation catalyst installed in front of the SCR catalyst at low exhaust gas temperature operation was compared. For an NSR catalyst system, the effect of fuel sulfur on both emissions and fuel economy during 50,000 km driving was examined. Furthermore, effects of other fuel properties such as distillation on exhaust emissions were investigated. The results show that sulfur is the influential factor for both devices. Namely, high NOx emission reduction performance of the Urea-SCR system with the oxidation catalyst at low exhaust gas temperature operation is influenced by sulfur.
Technical Paper

A Study for Understanding Carsickness Based on the Sensory Conflict Theory

2006-04-03
2006-01-0096
Two hypotheses based on the sensory conflict theory were postulated as possible means for reducing carsickness: (1) Reducing signals from the vestibular and vision systems through a reduction of low-frequency motion would mitigate carsickness and (2) Controlling stimulation of visual organs so as to reduce the amount of sensory conflict would mitigate carsickness. For hypothesis (1), the relations between subjective carsickness ratings and motions of the vehicle and passengers' body were investigated. Greater correlation was found between carsickness ratings and motions of the passengers' head, where the organs of the vestibular and vision systems are located, than between carsickness ratings and vehicle motions. For hypothesis (2), the incidence of carsickness in passengers who gazed at an in-vehicle display was investigated because there seemed to be large conflict between the vestibular system and the vision system.
Technical Paper

Development of a New 5.6L Nissan V8 Gasoline Engine

2004-03-08
2004-01-0985
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.
Technical Paper

Vehicle Cornering and Braking Behavior Simulation Using a Finite Element Method

2005-04-11
2005-01-0384
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.
Technical Paper

A Study of Drivers' Trust in a Low-Speed Following System

2005-04-11
2005-01-0430
Driving tests were conducted using an experimental vehicle equipped with an adaptive cruise control system incorporating low-speed following capability in order to evaluate drivers' trust in a driver support system. The results revealed that the drivers' trust in the system declined in cases where the control algorithm produced vehicle behavior that was inconsistent with their expectations. However, that decline in trust ceased to be observed as the drivers' understanding of the system improved. This result suggests a correlation between their understanding of the system and trust in it.
Technical Paper

Development of Innovative Variable Valve Event and Lift (VVEL) System

2008-04-14
2008-01-1349
Nissan Motor Company has developed a compact and simple new variable valve actuation system called VVEL (Variable Valve Event and Lift) that can vary intake valve lift and valve event angle in a wide range, and adopted it on a newly developed 3.7L, V6 engine. This system combined with a variable valve timing (VTC) mechanism (or a cam phaser) has substantially enhanced engine performance attributes, namely, fuel economy, exhaust emissions, and engine output, because the system has the ability to freely control all of intake valve lift, event duration angle and phasing between intake and exhaust valves. This paper describes an outline of the VVEL system, the principle of system operation, and effects on engine performance attributes by this technology.
Technical Paper

Real World Injury Patterns in Narrow Object Frontal Crashes: An Analysis of US Field Data

2008-04-14
2008-01-0527
Analyses were performed using field data for belted drivers of light vehicles in frontal crashes to examine the frequency and severity of frontal crashes with narrow objects. This study examined the distribution of injuries by body region, crash severity, and single- versus multiple-vehicle crashes for narrow object and all other crashes. Factors influencing injuries in different types of frontal crashes were identified, and risk of injury to belted drivers in narrow object crashes versus other frontal crashes was examined. A detailed review of about 400 NASS cases involving narrow object crashes was also performed. Results indicate frontal crashes involving impact with poles, posts, or trees are relatively infrequent. Overall, the fatal risk for belted drivers is lower in narrow object crashes than in other types of frontal crashes.
Technical Paper

A Study of a Method for Predicting the Risk of Crossing-Collisions at Intersection

2008-04-14
2008-01-0524
The probability or risk of traffic accidents must be estimated quantitatively in order to implement effective traffic safety measures. In this study, various statistical data and probability theory were used to examine a method for predicting the risk of crossing-collisions, representing a typical type of accident at intersections in Japan. Crossing-collisions are caused by a variety of factors, including the road geometry and traffic environment at intersections and the awareness and intentions of the drivers of the striking and struck vehicles. Bayes' theorem was applied to find the accident probability of each factor separately. Specifically, the probability of various factors being present at the time of a crossing-collision was estimated on the basis of traffic accident data and observation survey data.
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