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Technical Paper

The Effect of Belt-Drive CVT Fluid on the Friction Coefficient Between Metal Components

A block-on-ring friction and wear testing machine (LFW-1) was used as a test method for making fundamental evaluations of the effect of the Belt-Drive Continuously Variable Transmission(B-CVT) fluid on the friction coefficient between the belt and pulleys. The results confirmed that this method can simulate the friction phenomena between the belt and pulleys of an actual transmission. The mechanism whereby ZDDP and some Ca detergents improve the torque capacity of a B-CVT was also investigated along with the effect of the deterioration of these additives on the friction coefficient. It was found that these additives form a film, 80-90 nm in thickness, on the sliding surface, which is effective in increasing the friction coefficient. The friction coefficient declined with increasing additive deterioration. The results of a 31P-NMR analysis indicated that the decline closely correlated with the amount of ZDDP in the B-CVT fluid.
Technical Paper

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

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

The Development of a High Speed Steel Based Sintered Material for High Performance Exhaust Valve Seat Inserts

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.
Technical Paper

The Development of a Cobalt-Free Exhaust Valve Seat Insert

Generally, cobalt-contained sintered materials have mainly been applied for exhaust valve seat inserts (VSI). However, there is a trend to restrict the use of cobalt as well as lead environmental law, and cobalt is expensive. To solve these problems, a new exhaust VSI on the assumption of being cobalt and lead free, applicable for conventional engines, having good machinability, and with a reduced cost was developed. The new exhaust VSI is a material dispersed with two types of hard particles, Fe-Cr-C and Fe-Mo-Si, in the matrix of an Fe-3.5mass%Mo at the ratio of 15 mass % and 10 mass % respectively.
Technical Paper

The Development of Driveability Index and the Effects of Gasoline Volatility on Engine Performance

To reduce engine exhaust emissions, we have had to deal with this global environmental problem from the fuel side by introducing oxygenated fuels, reducing the RVP and using low aromatics. But when we change the fuel components and distillation, we must take note about how these affect the engine driveability. We have used T50, T90, RVP and so on as the fuel index up to the present. It is possible to characterize the fuel from one aspect, but these indexes don't always represent the real feature of the fuel. In this paper we propose a New Driveability Index (here in after referred to as NDI) that is more realistic and accurate than the other fuel indexes. We used a 1600cc DOHC L4 MPI type engine. We used Model Gasolines and Market Gasolines, see Appendix(1), (2) and (3), and tested them according to the Excess Air Ratio Response Test Method (here in after referred to as λ-R Test) that was suggested in SAE paper #930375, and we calculated the NDI statistically.
Technical Paper

Study on Air Bag Systems for Nissan Small-Sized Cars

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.
Technical Paper

Sinter Diffusion Bonded Idler Sprocket of Automotive Engine

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.
Technical Paper

Research on High Strength Material and Its Surface Modification for Parts Used Under Rolling Contact Cycles

This paper describes a newly developed steel composition and surface modification methods for improving the rolling contact fatigue strength of parts used in transmission systems, especially continuously variable transmissions (CVTs) to increase their torque capacity. The mechanisms of two types of typical rolling contact fatigue phenomenon in case hardening steel were examined with the aim of improving rolling contact fatigue strength. One concerned white etching constituents (WEC) and the other one concerned peculiar microstructural changes caused by hydrogen originating from decomposition of the lubrication oil as a result of repeated rolling contact stress cycles. The rolling contact fatigue strength limit due to WEC has been improved markedly by dispersing fine M23C6 alloy carbides in the martensite matrix at the subsurface layer of parts.
Technical Paper

Research Concentrated on An Experimental Method for Protecting Pedestrians

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.
Technical Paper

Reduction of Powerplant Vibration Level in the Acceleration Noise Region Based on Analysis of Crankshaft System Behavior

Increased attention has been directed toward noise and vibration characteristics of vehicles in recent years and the performance requirements in this area continue to become more rigorous every year. The acceleration noise in a frequency range of 250 ∼ 800Hz caused by powerplant vibration is important, and there is a need to reduce this noise level. In addition to reducing noise and vibration, however, there is also a growing need to achieve further weight reductions. Consequently, it is essential to reduce the weight of a powerplant without increasing its vibration levels. This make it necessary to predict powerplant vibration characteristics accurately at the planning and design stage so that suitable specifications can be determined. Specifications for reducing powerplant vibration have traditionally been found by experimentation. However, in powerplant excitation tests it has not been possible to take into consideration the effect of the crankshaft system on powerplant vibration.
Technical Paper

Oxidation Stability of Automatic Transmission Fluids -A Study by the International Lubricants Standardization and Approval Committee (ILSAC) ATF Subcommittee

The International Lubricant Standardization and Approval Committee (ILSAC) ATF subcommittee members have compared the two oxidation bench test methods, Aluminum Beaker Oxidation Test (ABOT) and Indiana Stirring Oxidation Stability Test (ISOT), using a number of factory-fill and service-fill ATFs obtained in Japan and in the US. In many cases, the ATFs were more severely oxidized after the ABOT procedure than after the same duration of the ISOT procedure. The relative severity of these two tests was influenced by the composition of the ATFs. The bench test oxidation data were compared with the transmission and the vehicle oxidation test data.
Technical Paper

On Fatigue Testing of Passenger Car Body Construction

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.
Technical Paper

New PM Valve Seat Insert Materials for High Performance Engines

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.
Technical Paper

New Copper Alloy Powder for Laser-Clad Valve Seat Used in Aluminum Cylinder Heads

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.
Technical Paper

Joint PAJ/JAMA Project - Development of a JASO Gasoline Bench Engine Test for Measuring CCDs

Detergent additives in automotive gasoline fuel are mainly designed to reduce deposit formation on intake valves and fuel injectors, but it has been reported that some additives may contribute to CCD formation. Therefore, a standardized bench engine test method for CCDs needs to be developed in response to industry demands. Cooperative research between the Petroleum Association of Japan (PAJ) and the Japan Automobile Manufacturers Association, Inc. (JAMA), has led to the development of a 2.2L Honda engine dynamometer-based CCD test procedure to evaluate CCDs from fuel additives. Ten automobile manufacturers, nine petroleum companies and the Petroleum Energy Center joined the project, which underwent PAJ-JAMA round robin testing. This paper describes the CCD test development activities, which include the selection of an engine and the determination of the optimum test conditions and other test criteria.
Technical Paper

Investigations of Compatibility of ETBE Gasoline with Current Gasoline Vehicles

Clarifying the impact of ETBE 8% blended fuel on current Japanese gasoline vehicles, under the Japan Clean Air Program II (JCAPII) we conducted exhaust emission tests, evaporative emission tests, durability tests on the exhaust after-treatment system, cold starting tests, and material immersion tests. ETBE 17% blended fuel was also investigated as a reference. The regulated exhaust emissions (CO, HC, and NOx) didn't increase with any increase of ETBE content in the fuel. In durability tests, no noticeable increase of exhaust emission after 40,000km was observed. In evaporative emissions tests, HSL (Hot Soak Loss) and DBL (Diurnal Breathing Loss) didn't increase. In cold starting tests, duration of cranking using ETBE 8% fuel was similar to that of ETBE 0%. In the material immersion tests, no influence of ETBE on these material properties was observed.
Technical Paper

Improvement in Pitting Resistance of Transmission Gears by Plasma Carburizing Process

The application of both high strength gear steels and shot peening technology has succeeded in strengthening automotive transmission gears. This technology, though, improves mainly the fatigue strength at the tooth root, but not the pitting property at the tooth face. Therefore, demand has moved to the development of new gear steels with good pitting resistance. In order to improve pitting resistance, the authors studied super carburizing which is characterized by carbide dispersion in the case, especially processed with a plasma carburizing furnace. Firstly, the influence of the carburizing temperature and carburizing period on the carbide morphology was investigated and the optimum carburizing conditions were determined. Secondly, the fatigue strength and pitting resistance was evaluated using carbide dispersed specimens.
Technical Paper

High Strength Steel for Cylinder Head Bolt

JIS SCM440M (SAE4140H), heat treated to the strength level of 120 to 140 kgf/mm2(171 to 199 ksi) -ISO 12.9 class-, is currently used for cylinder head bolts of Japanese passenger cars. Lower alloy steels, such as SAE 1541 for example, have not been substituted for JIS SCM440H so far because of their high susceptibility to delayed fracture. Daido Steel has tackled this problem and succeeded in applying the lower alloy SAE 1541 steel to 12.9 class cylinder head bolts by enhancing the resistance to delayed fracture by reducing impurities, especially sulphur. In this paper mechanical properties and delayed fracture characteristics of SAE 1541-ULS (Ultra Low Sulphur) steel are reported. 1541-ULS (S<0.005%, S+P< 0.020%) shows outstanding resistance to delayed fracture compared to conventional steel. Furthermore, the amount of MnS inclusions decreases remarkably in ULS steel, which results in high toughness.
Technical Paper

Finite Element Simulation of Ankle/Foot Injury in Frontal Crashes

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.
Technical Paper

Exhaust Noise Abatement with Porous Sintered Metal Silencer

The exhaust system is often one of the main sources of vehicle noise. A new type of exhaust silencer made of porous sintered aluminum and installed at the end of the exhaust tube considerably reduces this noise, with no rise in back pressure. The mechanism of noise abatement is analyzed utilizing fluid dynamic analysis techniques. It is concluded that noise reduction results mainly from the fluid dynamic effects arising from the gas permeability of the material. Among these effects are the boundary layer control effect of the inner flow, flattening of the velocity profile, heat dispersion effect, decrease in turbulence of flow, smoothing of exhaust pulsation, contraction of the mixing region, and the resulting large decrease in the volume of the noise source. In regard to acoustical effect, the sintered metal can be thought of as Helmholtz resonators. The change in the end condition as an acoustic tube also reduces the peak level of acoustic resonance.