Search Results

In this study, it is purpose to make clear the effect of cavitation phenomenon on the spray atomization. In this report, the cavitation phenomenon inside the nozzle hole was visualized and the pressure measurements along the wall of the nozzle hole were carried out by use of 25-times enlarged acrylic nozzle. For the representatives of regular gasoline, single and two-component fuels were used as a test fuel. In addition, various cavitating flow patterns same as experimental conditions were simulated by use of Barotropic model incorporated in commercial code of Star-CD scheme, and compared with experimental results.

An active suspension system controls a spring constant and an attenuater in real time using a power supply. Generally, the hydraulic pressures are used for transmitting the power. Therefore, a highly reliable and inexpensive control system has been required for a commercial use. This has been achieved by developing a mechanical fluid servo valve which comprises a simple combination of a solenoid valve and a spool valve. The technical problem of the valve vibrations has been solved through the numerical analyses, the fluid flow visualization tests and the vehicle tests.

In vehicle control systems such as ABS (anti-lock braking system) or active suspension control, sensors for detecting longitudinal and/or lateral acceleration of vehicles (acceleration of up to ± 9.8 m/s2, with frequency range of DC to 20 Hz) is necessary. The principle of acceleration detection for this sensor is as follows. A permanent magnet levitates steadily in magnetic fluid by the action of the magnetic field generated by the magnet itself. The magnet moves by the application of acceleration on the mass of the magnet. This change of position of the magnet is detected by the Hall element, and thus acceleration is measured as an electrical signal. This sensor consists of only magnetic fluid, a permanent magnet, housing, a pair of Hall elements and an electronic circuit.

The localized fire test provided in the Global Technical Regulation for Hydrogen Fuel Cell Vehicles gives two separate test methods: the ‘generic installation test - Method 1′ and the ‘specific vehicle installation test - Method 2′. Vehicle manufacturers are required to apply either of the two methods. Focused on Method 2, the present study was conducted to determine the characteristics and validity of Method 2. Test results under identical burner flame temperature conditions and the effects of cylinder protection covers made of different materials were compared between Method 1 and Method 2.

To verify the appropriateness of the vibration test conditions of ISO 12405, we performed tailoring to derive power spectrum densities and test durations as vibration test conditions. Vehicles used for tailoring included two electric vehicles and one plug-in hybrid electric vehicle. Those vehicles were equipped with accelerometers and were run on seven different road types at different speeds while data on the acceleration of the battery packs were recorded. The power spectrum densities for three axes that were derived from the obtained acceleration data were similar in form to the power spectrum densities of ISO 12405, and almost the same root mean square accelerations were obtained, confirming that they are appropriate. However, both experiments and theory suggest that the test duration for the Z-axis exceeds those of the X- and Y-axes.

In order to clarify future automobile technologies and fuel qualities to improve air quality, second phase of Japan Clean Air Program (JCAPII) had been conducted from 2002 to 2007. Predicting improvement in air quality that might be attained by introducing new emission control technologies and determining fuel qualities required for the technologies is one of the main issues of this program. Unregulated material WG of JCAPII had studied unregulated emissions from gasoline and diesel engines. Eight gaseous hydrocarbons (HC), four Aldehydes and three polycyclic aromatic hydrocarbons (PAHs) were evaluated as unregulated emissions. Specifically, emissions of the following components were measured: 1,3-Butadiene, Benzene, Toluene, Xylene, Ethylbenzene, 1,3,5-Trimethyl-benzene, n-Hexane, Styrene as gaseous HCs, Formaldehyde, Acetaldehyde, Acrolein, Benzaldehyde as Aldehydes, and Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene as PAHs.

An investigation based on human visual search functions was conducted into the causative factors of traffic accidents at clear intersections in rural areas. The results indicated that it is difficult for drivers to detect a vehicle traveling on a collision course because the vehicle remains in the same position in the driver's visual field. Two systems are introduced to assist drivers' visual searches. One system uses an image processing technique, and the other utilizes DGPS and IVC techniques. This paper presents the development of the assistance system.

The running direction of a vehicle can be controlled by not only wheel steer but also torque steer. This paper introduces the tractive torque steer effect produced by a newly developed electropneumatic control system, the limited-slip differential for large-sized vehicles. This system enhances the vehicle's running stability and controllability by controlling the tractive force of the drive axle. The tractive force maintains a stable running course against disturbances such as road roughness and wind gusts, thereby enhancing the steering response and providing a better feeling of handling to the driver. The system also improves mobility. especially on low-μ roads. It is expected that a single axle equipped with this system will exhibit good performance comparable to that of tandem axle.

Toyota succeeded in the fall of 1984 in manufacturing a complex engine and transmission control system using a newly developed single-chip microcomputer. This microcomputer, equipped with an 8K-byte ROM ( Read Only Memory) and a 256-byte RAM ( Random Access Memory), a powerful real time processing function, and a high-speed optimum instruction set, is better suited for automobiles. Application of the latest CMOS technology has enabled lower power consumption and improved noise immunity. The new system, which includes a new function; the electronic spark advance with knock control in addition to the conventional sophisticated system, has greatly improved the performance and driveability of vehicles.

TOYOTA MOTOR CORPORATION had developed the world's first microprocessor controlled suspension system, Toyota Electronic Modulated Suspension (TEMS), which is now being offered on the Toyota Soarer from Feb. '83. This system consists of sensors, switches, electronic control unit (ECU), actuators and shock absorbers. TEMS uses a microprocessor to adjust the damping forces of the front and rear shock absorbers. As a result, suspension can be tuned in two stages (hard and soft cushioning) and driver can choose three control modes (AUTO, SPORT, NORMAL). In AUTO mode, the TEMS system has achieved attitude controls (i.e. squat control, roll control and nosedive control). The TEMS system achieved a 15 - 30% decrease of squat, a 20 - 30% decrease of roll angle, a 10 - 30% decrease of nose-dive and a 30 - 40% decrease of shift-squat.

Advanced electronic control system of suspension and air springs are combined with the double wishbone type suspension. Damping force, spring rate and vehicle height can be automatically con-trolled among three levels in response to the vehicle running conditions.

Toyota has developed the world's first 8-speed automatic transmission (AA80E) for RWD automobiles. The transmission will first be used in the all-new Lexus LS460. In addition, a novel control system has been developed to maximize the predictability, response, efficiency, and initial quality of the powertrain while utilizing the high number of gear steps.

The torque converter clutch slip control system adopted in the Toyota A541E automatic transaxle engages the torque converter clutch by applying a steady slip speed to prevent the torque fluctuation of the engine to be transmitted to the drivetrain while enhancing the transmission efficiency of the torque converter. The feedback controller of the slip speed adopts the H∞ (H-Infinity) control theory which offers a high level of robust stability, and is the first of its kind in a mass produced component. As a result, a highly accurate and reliable system has been realized, contributing to large-scale fuel economy.

To prevent global warming, further reductions in carbon dioxide are required. It is therefore important to promote the spread of electric vehicles powered by internal combustion engines and electric vehicles without internal combustion engines. As a result, emissions from hybrid electric vehicles equipped with internal combustion engines should be further reduced. Interest in catalytic reactions in an electric field with a higher catalytic activity compared to conventional catalysts has increased because this technology consumes less energy than other electrical heating devices. This study was therefore undertaken to apply a catalytic reaction in an electric field to an exhaust emission control. First, the original experimental equipment was built with a high voltage system used to conduct catalytic activity tests.

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.

This paper describes the application of a life prediction method for stainless steel exhaust manifolds. Examination of the exhaust manifold cracks indicated that many of the failures could be attributed to out-of-phase thermal fatigue due to compressive strains that occur at high temperatures. Therefore, the plastic strain range was used as the crack initiation criteria. In addition, the comparison of the calculated thermal fatigue stress-strain hysteresis to the experimental hysteresis made it clear that it was essential to use the stress-strain data that was obtained through tensile and compression testing by keeping the test specimens at the maximum temperature of the thermal fatigue test mode. A finite element crack prediction method was developed using the aforementioned material data and good results were obtained.

The current hydrogen storage systems for fuel-cell vehicles are mainly a compressed hydrogen storage type, but it is known that the temperature inside the tank commonly increases while the tank is being filled with hydrogen. This study examines filling methods that prevent the temperature from exceeding the designed temperature of the tank. In order to propose a filling method that suppresses the temperature rise inside the tank and achieves filling within a short time, fast-filling tests were conducted on test tanks designed for fast filling of fuel cell vehicles. The detailed influences of the differences in type of tank and filling pressure on the rate of the internal temperature increase were investigated. Thermal responses were measured at various parts inside and outside the tank while varying the filling pressure, type of tank, tank capacity, filling time, and filling pattern, using a test tank that allows multi-point measurement of the internal temperature.

If a compressed hydrogen tank for vehicles is filled with hydrogen gas more quickly, the gas temperature in the tank will increase. In this study, we conducted hydrogen gas filling tests using the TYPE 3 and TYPE 4 tanks. During the tests, we measured the temperature of the internal liner surface and investigated its relationship with the gas temperature in the tank. We found that the gas temperature in the upper portion of the TYPE 4 tank rose locally during filling and that the temperature of the internal liner surface near that area also rose, resulting in a temperature higher than the gas temperature at the center of the tank. To keep the maximum temperature in the tank below the designed temperature (85°C) during filling and examine the representative tank internal temperatures, it is important to examine filling methods that can suppress local rises of tank internal temperature.

At the engine restart, when the temperature of the catalytic converter is low, additional fuel consumption would be required to warm up the catalyst for controlling exhaust emission.The aim of this study is to find a thermally optimal way to reduce fuel consumption for the catalyst warm up at the engine restart, by improving the thermal retention of the catalytic converter in the cool down process after the previous trip. To make analysis of the thermal flow around the catalytic converter, a 2-D thermal flow model was constructed using the thermal network method. This model simulates the following processes: 1) heat conduction between the substrate and the stainless steel case, 2) heat convection between the stainless steel case and the ambient air, 3) heat convection between the substrate and the gas inside the substrate, 4) heat generation due to chemical reactions.

One of the innovations for the Lexus LS400 is the development of a traction control system (TRAC system). The TRAC system suppresses the spinning of the driven wheels, which occurs easily on slippery roads during excessive acceleration, and it improves the acceleration performance and the stability of the car. The TRAC system controls the engine sub-throttle angle and the brake hydraulic pressure for the driven wheels in the same way as the traction control system for the 1987 Toyota Crown. But, acceleration performance and stability of Lexus LS400 is better than Crown as a result of good wheel spinning control by additional improvements of the throttle and brake control methods. Especially as the TRAC system controls the brake hydraulic pressure individually for left and right wheel, the car acceleration performance on split-μ surfaces is improved notably.