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In order to develop the valve rocker arm material for the new type engine, we investigated various materials whose chemical compositions were selected using 30% chromium cast iron, which had shown good results in screening evaluation tests, as the basis. High chromium cast irons are well known for their abrasive wear resistance, but it has been very difficult to apply them for use as rocker arm material because their machinability is very poor, and because it is difficult for them to have a regular microstructure. In this paper, both the manufacturing method for the rocker arm which decreases the disadvantages that high chromium cast iron have and the rocker arm material best suited for this method are described.

The SEA model of wind noise requires the quantification of both the acoustic as well as the turbulent flow contributions to the exterior pressure. The acoustic pressure is difficult to measure because it is usually much lower in amplitude than the turbulent pressure. However, the coupling of the acoustic pressure to the surface vibration is usually much stronger than the turbulent pressure, especially in the acoustic coincidence frequency range. The coupling is determined by the spatial matching between the pressure and the vibration which can be described by the wavenumber spectra. This paper uses measured vibration modes of a vehicle window to determine the coupling to both acoustic and turbulent pressure fields and compares these to the results from an SEA model. The interior acoustic intensity radiating from the window during road tests is also used to validate the results.

This research developed a new measurement technology for thermal analysis of the heat radiation from a hybrid transaxle case surface to the air and improved the heat radiation performance. This heat flux measurement technology provides the method to measure heat flux without wiring of sensors. The method does not have effects of wiring on the temperature field and the flow field unlike the conventional methods. Therefore, multipoint measurement of heat flux on the case surface was enabled, and the distribution of heat flux was quantified. To measure heat flux, thermal resistances made of plastic plates were attached to the case surface and the infrared thermography was used for the temperature measurement. The preliminary examination was performed to confirm the accuracy of the thermal evaluation through heat flux measurement. The oil in the transaxle was heated and the amount of heat radiation from the case surface was measured.

We have developed the world's first 8-speed automatic transmission for transverse FWD/4WD vehicles. The aim of this new automatic transmission was to achieve world-class fuel economy while offering both smooth gear shift and sporty shift feeling suitable for luxury cars. This has been accomplished using wide spread gear ratio, outstanding low drag components and highly efficient hydraulic control system. In addition, we have achieved the compactness similar to current 6-speed automatic transmission by adopting new gear train and compact clutch layout. In this paper, the detail of this automatic transmission is introduced.

A new automotive interior component material, TSOP-5 has been developed by refining the technology utilized to develop TSOP-1, the high modulus and high flow material for bumper covers. This new interior component material has excellent molding capability (MI=30dg/min.) yet still maintains high impact resistance which enables the material to be used in areas such as the dash board as well as trim covers requiring to meet the FMVSS 214, the new side impact regulation or the FMVSS 201, the new soft upper trim regulation.

The change of the fuel flow rate in an injector with mileage accumulation causes poor drivability and exhaust emission deterioration in Otto-type methanol fueled vehicles with a multi-point fuel injection system. This is one of the serious problems which needs to be solved for the practical use of methanol fueled vehicles. The investigation results reveal that the wear of contact surfaces between a valve needle and a valve body increases the resistance force for valve needle movement and causes the change of dynamic fuel flow rate in the injector. The effects of several countermeasures to solve this problem are evaluated.

As the demand for improved fuel economy increases and new CO2 regulations have been issued, aerodynamic drag reduction has become more critical. One of the important factors to consider is cooling drag. One way to reduce cooling drag is to decrease the air flow volume through the front grille, but this has an undesirable impact on cooling performance as well as component heat load in the under-hood area. For this reason, cooling drag reduction methods while keeping reliability, cooling performance and component heat management were investigated in this study. At first, air flow volume reduction at high speed was studied, where aerodynamic drag has the greatest influence. For vehicles sold in the USA, cooling specification tends to be determined based on low speed, while towing or driving up mountain roads, and therefore, there may be extra cooling capacity under high speed conditions.

One-box type vehicles are especially liable to a loss of stability when entering a region of cross-wind. The reasons for this instability were investigated using scale models and by means of a mathematical simulation. Results indicated that yawing moment attains a peak at a precise position of the vehicle relative to the cross-wind. Visualization of the air flow and measurement of the pressure distributions established the cause of the phenomenon. Furthermore a study was conducted into the effects of body shape on stability and the efficacy of various modifications was assessed.

Vehicle interior wind noise is typically managed through the overall exterior geometry of the vehicle, mirror shape and mounting location, sealing features and glass thickness and damping. Prior research has distinguished between contribution of fluctuating pressure due to air turbulence as compared to acoustic pressure to a passenger vehicles exterior at highway speeds. Because of the large difference in propagation speed between turbulent and acoustic pressure for on-road passenger vehicles, the structural response of the glass to turbulent versus acoustic pressure is not the same. The acoustic coincidence frequency of door glass is typically in the 2-3 kHz range. Turbulent coincidence frequency is much lower, and the effective transmission loss (TL) of the glass depends on the mix of turbulent and acoustic pressure on the exterior surface of the glass.

The structure of HCCI (homogeneous charge compression ignition) combustion flames was quantitatively analyzed by measuring the two-dimensional gas temperature distribution using phosphor thermometry. It was found from the relation between a turbulent Reynolds number and Karlovitz number that, when compared with the flame propagation in an S.I. engine, HCCI combustion has a wider flame structure with respect to the turbulence scale. As a result of our experimentation for the influence of low temperature reaction (LTR) using two types of fuel, it was also confirmed that different types of fuel produce different histories of flame kernel structure.

We have taken notice of Zn-Fe alloy electroplating with an eye to developing new corrosion-resistant steel sheets for automotive use with both cosmetic corrosion resistance and perforating corrosion resistance, and as a result of investigations into its paintability and corrosion resistance over the whole range of its compositions, we have come to a conclusion that steel sheets with two-layer Zn-Fe alloy electroplating that consists of a thin upper layer with a 75 to 85% Fe content and a lower layer with a 10 to 20% Fe content is the best choice.

Conventionally, sound insulation materials have been applied to control interior noise above 500 Hz, and damping materials to control interior noise below 500 Hz. In this paper, the noise control component for vehicle panels, which consists of damping material and sound insulation material, is investigated by using a two-degrees-of-freedom system. The investigation shows that sound insulation material can be effective in reducing interior noise below 500 Hz if its stiffness is reduced. This stiffness depends not only on the spring of the material itself but also on its pneumatic spring which is determined by air-flow resistance. This paper concludes with applications of techniques to reduce interior noise below 500 Hz by improving sound insulation materials.

The behavior of spray injections to turbulent duct flows from a slit injector for direct-injection gasoline engines was investigated using a combination of large eddy simulation (LES) and Lagrangian discrete droplet model (DDM). As a result, diffusion of droplets in stronger turbulent flows was observed at a later stage of the injection. Moreover, we compared calculation and experimental results by generating a pseudo-particle image from the calculation result.

The characteristic of In-Cylinder gas motion of a multivalve engine is compared with a single intake valve engine, which have been predicted by a three-dimensional numerical simulation and flow visualization. The measured intake valve outlet velocity from helical and straight port was adopted as the boundary conditions. The computer graphics technique has been utilized to express the predicted numerical results as moving picture like visualized flow. This flow pattern was compared with the actual flow pattern visualized with metaldehyde as the tracer using the bottom viewed engine, which showed good agreement. The prediction for the multivalve engine showed that the swirl velocity is rapidly reduced by interaction between the flows from the two port, but the turbulence kinetic energy is similar to that in the engines with a single intake valve with helical port.

The authors developed a high-reliability low-cost gold-plated connector for automobiles. The connector is covered with three plated layers, nickel, palladium-nickel alloy, and gold. The three-layer plating helps to reduce the required thickness of gold. This paper describes the reasons why palladium-nickel plating was adopted and compares the corrosion resistance, oxidation resistance and wear resistance of three-layer-plated materials with those of conventional gold-plated materials. In addition, the characterisitics of three-layer-plated connectors were compared with those of conventional gold-plated connectors. It was found that the reliability of three-layer-plated connectors was as high as that of conventional gold-plated connectors.

Engine friction reduction is an effective means to improve fuel consumption. Fluid friction reduction of main bearing is examined for engine friction reduction in cold condition. As one of the examinations, it was focused on low temperature of lubricating oil in the early stage during engine cold start. In hydrodynamic lubrication, the oil film temperature is maintained by balance between heat generation and heat transfer. The heat generation is generated by shear of lubricating oil. The factors of the heat transfer, the following elements are considered as follows, A) The heat transfer to a crank shaft, B) The heat transfer to a bearing, C) The heat transfer by convection. If the heat generation is constant, oil film temperature is increased by reduction of heat transfer. It is considered that the reduction of oil leakage and reduction of the heat transfer by convection is equivalent.

Previous studies and recent practical aerodynamic evaluations have shown that aerodynamic drag of passenger vehicles with “ground simulation” with moving ground and rotating wheels may increase in some cases and decrease in other cases relative to the fixed ground and stationary wheel conditions. Accordingly, the effects of the ground simulation on the aerodynamic drag should be deeply understood for further drag reduction. Although the previous studies demonstrated what is changed by the ground simulation, the reason for the change has not been fully understood. In this article, the effects of wheels and wheel houses attachment and those by the ground simulation with ground movement and wheel rotation on the aerodynamic drag were investigated by quantification of the underfloor flow that plays a crucially important role on the formation of vortical structure around vehicles.

To reduse crosswind sensitivity, the yaw moment should be decreased under both transient and steady conditions. The transient condition is when a vehicle comes out immediately from a tunnel into a crosswind while the steady condition is when driving straight along the coastline. After studying the pressure distribution and the flow pattern around the body, we have reached the ideal air flow at the front-side corner that reduces the yaw moment under both conditions. And we have devised an entirely new method to achieve this better air flow. The method uses an internal flow generated by a pressure difference in the flow feeld to create a jet effect and by using only a duct for internal flow to control the outside air flow. It is done without any change to the exterior styling, except at the flow exit. We call it “Aero Slit”. This “Aero Slit” is effective only under crosswind conditions, and does not increase aerodynamic drag when a crosswind is not blowing.

A new partial strengthening method, TIG (Tungsten Inert Gas) remelting process, for automobile aluminum alloy castings is described. The preferable operating variables to strengthen, and metallurgical-mechanical properties of remelted alloys formed under selected conditions have been investigated. As a result, the mechanical properties such as strength and toughness, and thermal crack resistance of the remelted alloys were improved markedly due to the effects of microstructure refining and cast defects decrement by remelting. So, the application studies for automobile parts to meet the characteristics of this process have been carried out. Consequently, TIG remelting process has been practically used as an available strengthening method for the portion between valve ports of high performance diesel engine cylinder head.

A camshaft for an automobile engine is generally made of chilled cast iron. But, because of increased demand for higher performance engines, a camshaft with many camshaft has been expected. The cam intervals were necessarily narrow. So it was difficult to manufacture the conventional chilled cast iron camshaft at a moderate price. In the case of a rocker-arm type valve mechanism, higher wear resistance was necessary. After due consideration to solve these problems, development of surface remelted chilled layer camshafts by Toyota's unique manufacturing method has been accomplished. In 1984 Toyota Motor Corporation started the mass-production of this camshaft, first for the new 1.0 liter 1E engine, and then for the 1.3 liter 2E engine. In this paper, the excellent wear resistance, the low manufacturing cost and the characteristic manufacturing method are described.