Search Results

The renewed platform of the upcoming flagship front-engine, rear-wheel drive (FR) vehicles demands high levels of driving performance, fuel efficiency and noise-vibration performance. The newly developed driveline system must balance these conflicting performance attributes by adopting new technologies. This article focuses on several technologies that were needed in order to meet the demand for noise-vibration performance and fuel efficiency. For noise-vibration performance, this article will focus on propeller shaft low frequency noise (booming noise). This noise level is determined by the propeller shaft’s excitation force and the sensitivity of differential mounting system. In regards to the propeller shaft’s excitation force, the contribution of the axial excitation force was clarified. This excitation force was decreased by adopting a double offset joint (DOJ) as the propeller shaft’s second joint and low stiffness rubber couplings as the first and third joints.

In order to achieve good adhesive properties, typical decorative plastic plating technology uses a chromic acid process that creates an anchor effect. Due to environmental concerns with hexavalent chromium, there is a need to find alternative processes. Pretreatment using highly concentrated ozonized water was investigated as a novel approach to achieving this goal. In the conventional chromic acid process, strong adhesion between plating membranes is achieved by roughing the ABS (acrylonitrile-butadiene-styrene) resin surface by approximately 1 um. On the other hand, the highly concentrated ozonized water process achieves good adhesion with a smooth resin by changing the resin from ABS to ASA (acrylate-styrene-acrylonitrile). It was discovered that the difference in this strength of adhesion was the difference in resin surface strength (existence of deterioration or otherwise).

The development of an alternative oxygen reduction electrocatalyst to platinum based electrocatalysts is critical for practical use of the polymer electrolyte membrane fuel cell (PEMFC). Transition metal sulfide chalcogenides have recently been reported as a possible candidate for Pt replacement. Our work focused on chalcogenides composed of ruthenium, molybdenum, and sulfur (RuMoS). We elucidate the factors affecting electrocatalytic activity of carbon supported RuXMoY SZ catalyst. This was demonstrated through a correlation of oxygen reduction reaction (ORR) activity of the catalysts with structural changes resulting from designed changes in sulfur composition in the catalysts.

This article proposes a rubber suspension bushing model considering amplitude dependence as a useful tool at the initial design phase. The purpose of this study is not to express physical phenomena accurately and in detail and to explore the truth academically, but to provide a useful design method for initial design phase. Experiments were carried out to verify several dynamic characteristics of rubber bushings under vibration up to a frequency of 100 Hz, which is an important frequency range when designing ride comfort performance. When dynamic characteristic theory and the geometrical properties of the force-displacement characteristic curve were considered using these dynamic characteristics as assumptions, an equation was derived that is capable of calculating the dynamic stiffness under an arbitrary amplitude by identifying only two general design parameters (dynamic stiffness and loss factor) under a reference amplitude.

Underbody coating is used to prevent chipping damage of the automobile underbody and wheel well. Multi-functional material that gives sound insulating properties is called sound insulating underbody coating. This paper describes the development of underbody coating material with powdered acrylic composition as an alternative to polyvinyl chloride resin. The new material also has better foaming properties. It is possible to ensure excellent sound insulating performance with thin film. This multi-functional underbody coating is the first application in the world with weight reduction and cost saving, and in a more environmentally acceptable manner.

From the viewpoint of measures for environmental issues, the amount of solvents in paint for aluminum wheels needs to be minimized. Environmentally friendly powder coatings have been used widely for primer coating and clear coating, but there is no precedent for its use for base coating. This time, we optimized the condition of surface treatment of pigment and hardening behavior of constituent resin in the melting process and succeeded in developing a metallic powder coating for aluminum wheels that fulfills the appearance and the quality requirements of aluminum wheels.

Through a polymer design and precise morphology control, The Super Olefin Polymer, TSOP-1 and TSOP-5 were developed for the material consolidation of interior and exterior parts, respectively. Due to a good balance of TSOP performance, several conventional materials were consolidated into one material for each application. Accordingly, considerable amounts of weight reduction and cost savings have been obtained. In addition to the excellent recyclability of TSOP, the coated bumpers collected from the market were re-utilized through paint decomposition technology. The first dashboard construction, molded partially with foam-padded skin, was also realized. The current amount of TSOP used in a vehicle is about 30% of the total amount of plastic materials. Through the usage of TSOP, 70% of the material consolidation has been achieved.

To meet the market requirement for headlamps having lower power consumption, high photometric performance and long life whilst providing new styling opportunities, it has been anticipated that LED light sources would provide the necessary technological basis. Against this backdrop, Koito has succeeded in developing the necessary headlamp technologies and commercializing the world's first headlamp utilizing white LED's. The key point is that the various challenges associated with the development of an LED headlamp such as the commercial application of a synthesized light distribution, control of the light axis structure for the multi-lamp system, development of adequate thermal management for the cooling of the LED's and the achievement of volume production of the lamps have been successfully overcome.

We studied the use of Bio-plastics (plastics made from plants) such as poly(lactic acid) (PLA) to automotive parts. To apply this material to automotive plastic parts, improvement in heat and impact performance is required. From the viewpoint of suppressing the increase in CO2 emissions, we attempted to improve the performance of PLA by combining with natural fiber. As the result, we could improve both heat and impact performance. In addition, we could achieve higher modulus and lower bulk density, which leads to the weight reduction of automotive parts.

We studied the application of Bio-plastics (plastics made from plants) such as poly(lactic acid) (PLA) to automotive parts. To apply this material to automotive plastic parts, major improvement is required for thermal and impact performance. From the viewpoint of suppressing the increase CO2 emissions, we attempt to improve the performance of PLA by combining with natural fiber. As the result, we could improve both thermal and impact performance. In addition, we could achieve higher modulus and lower bulk density, which lead to the weight reduction of automotive parts.

We studied the adoption of plastics derived from plants (bioplastics) such as poly(lactic acid) (PLA) for automotive parts in order to contribute to suppressing the increase in CO, emissions. For this application. major improvements of heat and impact resistance are needed. As a method to improve heat resistance, we developed PLA combined with clay of high heat resistance. As a result. we succeeded in synthesizing a PLA-clay nanocomposite using 18(OH)2-Mont. In-mold crystallization of PLA-clay nanocomposite lead to the great suppression of storage modulus decrease at high temperature. which in turn improved the heat resistance of PLA.

In this report, adhesion mechanism between epoxy resin and primer and between primer and Ni platting in Hybrid vehicle (HV) was investigated. Adhesion forces are thought to be a combination of mechanical bond forces (such as anchor effect), chemical bond forces and physical bond forces (such as hydrogen bonding and Van der Waals force). Currently there is insufficient understanding of the adhesion mechanism. In particular, the extent to which the three bond forces contribute to adhesion strength. So the adhesion mechanism of polyimide primers was analyzed using a number of different methods, including transmission electron microscope (TEM) and atomic force microscope (AFM) observation, to determine the contributions of the three bonding forces. Molecular simulation was also used to investigate the relationship between adhesion strength and the molecular structure of the primer.

The use of a head-up display (HUD) system has become popular recently, as it can provide feedback information at a position easily seen by the driver. However, the outline of the HUD bezel often reflects on the windshield of a HUD equipped vehicle. This phenomenon occurs when the sun is at a high position and reflects off the top of the instrument panel and the front view is dark. For this reason, it can occur when driving on asphalt paved roads, causing annoyance to the driver. Under fixed environmental conditions, the vehicle based factors that influence the annoyance caused by reflected boundary lines are the position of the reflection, line thickness, and the contrast of the reflected boundary line. These can be represented by the conspicuity of a striped pattern (contrast sensitivity function). In previous research in 1991, M. S. Banks et al. studied a contrast sensitivity function that included the factors stated above.

This paper describes a new method for objective evaluation of wind noise in the passenger compartment of a car. The loudness and direction of noise in each frequency band can be estimated by performing analyses based on human hearing properties. Therefore, those wind noise components that are annoying to the passengers or those wind noise components whose source location can be determined by the human listener can be identified objectively. Furthermore, the total loudness of wind noise can be estimated quite precisely by adding the loudness of the frequency bands for noise emanating from the direction of the side window.

In this study, we evaluated subjective nighttime discomfort-glare responds on three different types of planar and non-planar driver-side mirrors on two age groups. Fifty-six individuals (28 young [18-35 years] and 28 old [65 years and over]) participated in this experiment. Subjective discomfort-glare rating scores on three different types of driver-side mirrors were assessed utilizing De Boer's rating scale in a controlled nighttime driving environment (laboratory ambient illuminant level - l lux with headlight turned off). Three driver-side mirrors included: planar (“flat mirror” - reflectance ratio of 39.12%) and nonplanar (“curved mirror” - reflectance ratio of 8.78% and “blue mirror” - reflectance ratio of 7.77%; R=1400mm). The results indicated that with the same glare level (as measured by angle of incidence and illuminance on the front of the eyes), older adults reported lower De Boer's rating scores (i.e. worse feelings of glare) than their younger counterparts.

Toyota is implementing various technical developments in various fields for protection of environment. Reducing the fuel consumption is a matter of great urgency for the reduction of CO2 emissions. In the technology of vehicle body development, mass reduction and the improvement of aerodynamics are mainly important for fuel economy. As the one of way for this, we adopted resin glass as the back door glass of ES3, small-sized low-fuel consumption vehicle. (Figure 1,2,3) The first advantage of resin glass is the low density that weights about a half of inorganic glass. However resin glass is needed higher thickness for equivalent rigidity, as the result approximately 41% mass reduction was achieved. However resin glass is relatively expensive. Therefore it seems to be difficult to expand the usage of resin for this application. Then, we focused on additional advantage of resin glass, in order to make good use of resin glass. The second advantage of resin glass is design flexibility.

Silver metallic colors with thin and smooth aluminum flake pigments have been introduced for luxury brand OEMs. Regarding the paint formulation for these types of colors, low non-volatile(NV) and high aluminum flake pigment contents are known as technology for high metallic appearance designs. However, there are two technical concerns. First is mottling which is caused by uneven distribution of the aluminum flake pigments in paint film and second is poor film property due to high aluminum pigment concentration in paint film. Therefore, current paint systems have limitation of paint design. As a countermeasure for those two concerns, we had investigated cellulose nanofiber (CNF) dispersion liquid as both the coating binder and rheology control agent in a new type of waterborne paint system. CNF is an effective rheology control agent because it has strong hydrogen bonds with other fiber surfaces in waterborne paint.

Since bumper reinforcements are positioned at front/rear ends of vehicles, weight reduction of the bumper reinforcements enhances vehicle dynamic performance by reducing a yaw moment of inertia. CFRP (Carbon Fiber Reinforced Plastic) composites are attractive lightweight materials due to their excellent specific strength and rigidity. However, because of their relatively high cost, applications of CFRP materials to vehicle structural parts are limited. In this study we have developed a lightweight, structural part, which consists of a thin-walled Al (Aluminum) bumper reinforcement with a UD (Unidirectional)-CFRP sheet. The intention is to prevent an increased part cost by reducing the amount of Al and by minimizing the amount of CFRP. Compared to Al, UD-CFRP sheets have even higher tensile strength and modulus. When vehicles crash, bumper reinforcements may be subjected to bending force.

Thermoplastic polyurethane (TPU) Powder Slush material for automotive interior parts, like instrument panels and door trim was developed as an alternative material for polyvinyl chloride (PVC) Powder Slush. Generally, TPU has poor anti-alcohol performance. However this performance has to be improved for automotive interior parts because the common cleaner solvent for interior parts usually contains some type of alcohol. Through our study of various TPU formulas, sufficient anti-alcohol performance was achieved by introducing aromatic polyol. Due to negative effects of aromatic polyol for low temperature and melting properties, additional study for plasticizer was essential. These properties are important for air bag deployment performance and moldability of powder slush. In order to solve these problems, various types and amounts of plasticizer were studied. Benzoic ester produced the best balance between compatibility with urethane polymer and anti-fogging performance.

Weight reduction for a fuel cell vehicle (FCV) is important to contribute a long driving range. One approach to reduce vehicle weight involves using a carbon fiber reinforced plastic (CFRP) which has a high specific strength and stiffness. However, a conventional thermoset CFRP requires a long chemical reaction time and it is not easy to introduce into mass production vehicles. In this study, a new compression-moldable thermoplastic CFRP material for mass production body structural parts was developed and applied to the stack frame of the Toyota Mirai.