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Technical Paper

A Study of Technology for Assembling Vehicle Endurance Reliability

1991-09-01
911924
The ways in which vehicles are used in the field are continually becoming more diverse. In order to provide the optimum solution with respect to performance and weight, it is necessary to be able to assure vehicle endurance reliability with a high degree of accuracy in relation to the manner of use in each market. This situation has increased the importance of accurately quantifying the ways in which vehicles are used in the field and of designing vehicles with sufficient endurance reliability to match the usage requirements. This report presents a “market model” by which the manner of usage in the field can be treated quantitatively using combinations of environmental factors that influence the road load, drive load and corrosion load, representing typical loads vehicles must withstand.
Technical Paper

Nissan's New Production System: Intelligent Body Assembly System

1991-02-01
910816
Car makers are working hard today to shorten development and production lead times through the use of flexibile manufacturing systems(FMSs)to meet diversified and individualized customer requirements. To achieve this goal, Nissan has been developing many kinds of new technologies and systems such as: (1) the intelligent body assembly system for body assembly processes; (2) a press die stamping simulation method and unified database for press die manufacturing; (3) a robot and facility teaching system using CAD data; (4) an automated assembly line for trim and chassis assembly operations. These new FMS methods have been implemented in many manufacturing areas, including the stamping shop, body assembly shop, painting shop and trim and chassis shop. This paper focuses mainly on the intelligent body assembly system as a typical example of the new production systems and technologies being developed at Nissan.
Technical Paper

Development of Multi-Layer Plastic Fuel Tanks for Nissan Research Vehicle-II

1987-02-01
870304
Plastic fuel tanks are light in weight and rustproof, and have good design flexibility. For those currently in use, however, which are made of mono-layer high-density polyethylene, fuel permeability is too high to meet U.S. evaporative emission standards, which are stricter than those in Japan or the EEC. For minimize fuel permeation, the formation of a harrier layer of polyamide resin by multilayer (three-resin five-layer) blow molding is considered more promising than sulphonation or fluorination treatment of the polyethylene resin. This paper describes the fuel permeation mechanism, then outlines the development of a multi-layer plastic fuel tank, discussion its structural features and the development of resins.
Technical Paper

High Performance Differential Gear

1989-02-01
890531
Excellent fuel economy and high performance have been urgent in Japanese automobile industries. With increasing engine power, many of the power train components have to withstand higher loads. Differential pinion gear being one of those highly stressed parts, excellent fatigue and shock resistance have been demanded. At first the fundamental study on the fatigue and impact crack behavior of carburized components was studied and the new grade composed of 0.18%C-0.7%Mn-1.0%Cr-0.4%Mo was alloy designed. Furthermore, Si and P is reduced less than 0.15 and 0.015%, respectively aiming at the reduction of intergranular oxidation and improved case toughness. The differential gear assembly test has proved that the new grade shows three times as high impact strength as that of conventional steel, SCM418, and almost the same as that of SNCM420 containing 1.8%Ni.
Technical Paper

Extremely Formable Cold Rolled Sheet Steel with Ultra-High Lankford and n Values - Metallurgy and Formabilities

1993-03-01
930783
Extremely formable cold sheet steel with an ultra-high Lankford value of more than 2.5 and an n value of more than 0.27 has been developed. This steel is obtained due to the following factors; using extremely pure IF (Interstitial free) steel, immediate rapid cooling upon completion of rolling in the hot rolling process, a high reduction in the cold rolling process, and a high soaking temperature in the continuous annealing process. This steel sheet shows excellent deep drawability and stretch formability compared with conventional steel sheet (former IF steel and low carbon aluminum-killed steel) as a result of evaluating the limiting drawing ratio and limiting dome height, respectively. This excellent formability is also shown by the model forming tests for simulating the actual stamping of an oilpan and a side-panel. Furthermore, this steel shows the same spot-weldability as that of former IF steel, and zinc phosphatability similar to that of low carbon aluminum-killed steel.
Technical Paper

Development of Laser-Textured Dull Steel Sheets with Superior Press Formability

1993-03-01
930808
Surface roughness of steel sheet for automotive use is one of the most important control items, because the surface roughness influences image clarity of painted surface, press formability and easiness in handling during manufacturing and processing of steel sheets. Laser texturing technology is introduced into a roll finishing process of cold rolling, and new type of regular surface roughness profile can be processed on the surface of steel sheets. Effective application method of this technology is investigated at the present day. In Japan, Laser-textured dull steel sheets are used for outer-panels of automotive body as the first application. And image clarity after painting of outer panels has been successful in improving. Nowadays, Laser texturing technology is actually used for manufacturing the high image clarity steel sheets, and they are manufactured in large quantities. Another application of Laser texturing technology is for the inner parts which require pressformability.
Technical Paper

On-Line Painted Thermal Plastic Exterior Body Panels for Nissan Be-1 and Application to CAE

1988-02-01
880034
This paper describes the plastic body panels developed for the Nissan Be-1 which was released and put on sale in Japan in January 1987. The panels include four body parts: left and right front fenders, front apron and rear apron. They are made of a thermoplastic resin and are produced by injection molding. The top paint coat can be sprayed on all four panels simultaneously with other steel body panels. The panels provide a high-quality appearance that is in no way inferior to the paint quality of steel panels. This is true during initial use as well as over long periods of time. Besides providing weight reductions, they also deliver improved resistance to impacts. CAE process was applied to develop these panels and proved to be quite effective.
Technical Paper

Analysis of Disc Brake Squeal, 1992

1992-02-01
920553
Eliminating squeal noise generated during braking is an important task for the improvement of vehicle passengers' comfort. Considerable amount of research and development works have been done on the problem to date. In this study, we focused on the analyses of friction self-excited vibration and brake part resonance during high frequency brake squeal. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding velocities. Its vibration frequency can be calculated in relation to the mass and stiffness of the pad sliding surface. Frequency responses of the brake assembly were measured and the vibration modes of the pad, disc and caliper during squeal were identified through modal analysis. Further study led to the development of a computer simulation method for analyzing the vibration modes of brake parts. Analytical results obtained using the method agreed well with the corresponding experimental data.
Technical Paper

An Application of Structural-Acoustic Coupling Analysis to Boom Noise

1989-09-01
891996
Reduction of interior noise is an important factor in vehicle design and many experimental and theoretical studies have been carried out to find effective noise reduction techniques. Previously, we developed a Structural-Acoustic Uncoupled Program, ACOUST3, as a technique for estimating low-frequency noise in the vehicle interior. In the present work, ACOUST3 has been extended to construct an acoustic coupling analysis system, ASCA, which is used to calculate low-frequency noise, such as boom noise. In order to calculate low-frequency noise accurately, it is necessary to represent the vibration characteristics of the trimmed body as closely as possible. To do this, we built a trimmed body model, incorporating 22 trim parts, based on vibration test results, and found that the calculated results obtained with the model correlated well with experimental data.
Technical Paper

Discharge Regulator of Painting Robot and Establishment of CAD Teaching System

1988-11-01
881747
The current spray painting system is hardly considered that the thickness is controlled enough, because the temperature greatly influence on the viscosity of paint. We noticed the problem and detected the temperature at a nozzle of a spray unit. We tried that the paint flow is controlled to get stable thickness more accurately by the temperature feedback system. We also tried to develop the new programming method of robots. This new offline programming system provided us an ideal positions and orientations of the spray gun mounted on a robot wrist, after several simulation in the CAD system. We checked and debugged the office taught date with a trial robot in a trial area, and then loaded down with the date to a target robot. We eventually provided a better production technology with the paintflow control system together with the new CAD based offline programming system.
Technical Paper

Application of 980 MPa Grade Advanced High Strength Steel with High Formability

2018-04-03
2018-01-0625
There are strong demands for vehicle weight reductions so as to improve fuel economy. At the same time, it is also necessary to ensure crash safety. One effective measure for accomplishing such both requirements conflicting each other is to apply advanced high strength steel (AHSS) of 780 MPa grade or higher to the vehicle body. On the other hand, higher strength steels generally tend to display lower elongation causing formability deterioration. Nissan Motor Corporation have jointly developed with steel manufacturers a new 980 MPa grade AHSS with high formability with the aim of substituting it for the currently used 590 MPa grade high-tensile steel. Several application technologies have been developed through the verifications such as formability, resistance spot weldability, crashworthiness, and delayed fracture.
Technical Paper

Down-Gauging Outer Body Panels Through the Use of Rib-Shaped Plastic Reinforcement

1983-06-06
830979
Down-gauging outer panels is an effective method for reducing the weight of an automobile body. We have succeeded in narrowing the thickness of outer panels by using rib-shaped plastic reinforcement. The plastic reinforcement consists of unhardened resin and an adhesive sheet, and it conforms well to the curved panel surface. In the body paint oven, it is hardened on the outer panels and forms a rib-shaped structure. This paper describes the composition of the resin material, the manufacturing process and the strength and rigidity of outer panels made with the rib-shaped reinforcement. It also discusses the weight reduction effect achieved by applying these panels to the doors of a production vehicle.
Technical Paper

Positioning System with Vision Sensor for Automatic Arc Welding

1986-02-01
860607
This report describes an arc-welding robot system with a vision sensor which Nissan Motor Co., Ltd. has introduced to automate the arc welding line for truck frames. Developed in-house, this system is now in operation on the arc welding line for Nissan Truck frames at Nissan's Kyushu plant. In developing the system, primary emphasis was placed on assuring practicality and high reliability. Included among the prominent features of the system is the capability to detect the welding line of thin panels with a high degree of accuracy and to calculate corrections when needed. To assure the high speed and reliability needed for the production line, the robot and sensor are separated, and the vision sensors are placed at fixed positions. Detection of the welding line and transmission of data to the robots to correct their positions are completed just prior to welding, so as to avoid the effects of noise and the arc flash during welding.
Technical Paper

Measurement of Piston and Piston Ring Assembly Friction Force

1985-10-01
851671
A new method for measuring friction has been developed in order to analyze piston and piston ring assembly friction force during engine operation. While this method does not require extensive modification to the piston or cylinder, two extra compression and expansion strokes each are added at the end of the conventional four-stroke cycle. In these measuring strokes, the gas pressure and temperature are maintained at firing levels, and friction force characteristics of the piston and piston ring assembly are measured continuously while the burned gas is compressed and expanded.
Technical Paper

The Development on Cold Forging Technique to form a Component of the Constant Velocity Joint

1985-02-01
850353
Cold forging has been applied to form a component of the constant velocity joint. This part, slide joint housing, is made of JIS S48C (SAE 1048) high carbon steel. As it has been very difficult to form this part by cold forging, it has been formed by hot forging up until now. Success was obtained in forming this part by cold forging through improving the chemical composition of S48C high carbon steel and tool design, determining the optimum condition for heat treating the slug, and using a TiC coated punch. Since this slide joint housing, which is nearly net shape, was able to be formed through this cold forging technique, material saving was improved about 40% and machining time was reduced much in comparison with hot forging. Manufacturing cost can be greatly reduced through this cold forging which has been developed.
Technical Paper

Thermal Imaging Technology using a Thermoelectric Infrared Sensor

2008-04-14
2008-01-0912
This paper describes a low-cost 48 × 48 element thermal imaging camera intended for use in measuring the temperature in a car interior for advanced air conditioning systems. The compact camera measures 46 × 46 × 60 mm. It operates under a program stored in the central processing unit and can measure the interior temperature distribution with an accuracy of ±0.7°C in range from 0 to 40°C. The camera includes a thermoelectric focal plane array (FPA) housed in a low-cost vacuum-sealed package. The FPA is fabricated with the conventional IC manufacturing process and micromachining technology. The chip is 6.5 × 6.5 mm in size and achieves high sensitivity of 4,300 V/W, which is higher than the performance reported for any other thermopile. This high performance has been achieved by optimizing the sensor's thermal isolation structure and a precisely patterned Au-black absorber that attains high infrared absorptivity of more than 90%.
Technical Paper

Spot-weld Layout Optimization for Body Stiffness by Topology Optimization

2008-04-14
2008-01-0878
In general, the improvement of vehicle body stiffness involves a trade-off with the body weight. The objective of this research is to derive the lightest-weight solution from the original vehicle model by finding the optimized spot-weld layout and body panel thickness, while keeping the body stiffness and number of spot welds constant. As the first step, a method of deriving the optimal layout of spot welds for maximizing body stiffness was developed by applying the topology optimization method. While this method is generally used in shape optimization of continuous solid structures, it was applied to discontinuous spot-weld positions in this work. As a result, the effect of the spot-weld layout on body stiffness was clarified. In the case of the body used for this research, body stiffness was improved by about 10% with respect to torsion and vertical and lateral bending.
Technical Paper

Low-cost FC Stack Concept with Increased Power Density and Simplified Configuration: Utilizing an Advanced MEA with Integrated Molded Frame

2011-05-17
2011-39-7260
In 2006, Nissan began limited leasing of the X-TRAIL FCV equipped with their in-house developed Fuel Cell (FC) stack. Since then, the FC stack has been improved in durability, cold start-up capability, cost and size with the aim of promoting full-scale commercialization of FCVs. However, reduction of cost and size has remained a significant challenge because limited mass transport through the membrane electrode assembly (MEA) has made it difficult to increase the rated current density of the FC. Furthermore, it has been difficult to reduce the variety of FC stack components due to the complex stack configuration. In this study, improvements have been achieved mainly by adopting an advanced MEA to overcome these difficulties. First, the adoption of a new MEA and separators has improved mass transport through the MEA for increased rated current density. Second, an integrated molded frame (IMF) has been adopted as the MEA support.
Technical Paper

Mechanism Analysis on LSPI Occurrence in Boosted S. I. Engines

2015-09-01
2015-01-1867
Mechanism of suddenly occurring behavior of low speed pre-ignition (LSPI) in boosted spark ignition (SI) engines was analyzed with various experimental methodologies. Endoscope-visualized 1st cycle of LSPI showed droplet-like luminous flame kernels as the origin of flame propagation before spark ignition. With the oil lubricated visualization engine, droplets flying were observed only after enough accumulation of fuel at piston crevice. Also, it was confirmed that subsequent cycles of LSPI occur only after enough operation time. These results indicated that local accumulation of liner adhered fuel and saturation of oil dilution can be a contributing factor to the sudden occurrence of LSPI.
Technical Paper

Development of GF-5 0W-20 Fuel-Saving Engine Oil for DLC-Coated Valve Lifters

2014-04-01
2014-01-1478
A suitable GF-5 engine oil formulation is investigated to improve the fuel economy of gasoline engines with hydrogen-free DLC-coated valve lifters. Molybdenum dithocarbamate (MoDTC) is shown to be a suitable friction modifier for low viscosity grade engine oils like 0W-20. A suitable Ca salicylate detergent is also determined from several types examined for maximizing the friction reduction effects of MoDTC. The most suitable Ca salicylate has a chemical structure capable of forming a borophosphate glass film on metal surfaces, which is known to improve the effects of MoDTC. A high viscosity index Group III base oil (VI>140) is also effective in improving fuel efficiency. It is further clarified that the structural design of the polymethacrylate viscosity modifier is another important factor in reducing engine friction.
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