Refine Your Search



Search Results

Technical Paper

Toyota New Compact Five-Speed Automatic Transmission for RWD Passenger Cars

A new compact five-speed automatic transmission (A650E) has been developed for front engine rear wheel drive cars. The development of this transmission has been aimed at improving fuel consumption, power performance, engine noise reduction during highway cruising and smooth acceleration by employing a wide range of gearing and close gear ratios. Generally a five-speed automatic transmission is larger than a four-speed, because of additional friction elements and gears. This can result in a change in the floor panel of the car body. However, by removing a one-way clutch for second gear and employing a unique gear-train layout, this transmission has the same circumference and length as the conventional four-speed automatic transmission (A340E)(1).1 In order to reduce first or second gear noise, gear specification and supporting structures of planetary gears have been optimized by FEM analysis.
Technical Paper

Thermal Fatigue Life Prediction for Stainless Steel Exhaust Manifold

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.
Journal Article

Thermal Analysis of the Exhaust Line Focused on the Cool-Down Process

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.
Technical Paper

The application of VHDL-AMS multi-domain HV simulation to the power performance and the fuel economy during warming up process

In order to reduce CO2, EV and Hybrid Vehicle (HV) are effective. Those type vehicles have different power train from conventional vehicle. Those new power trains drastically improve their efficiency from conventional vehicle with keeping same or superior power performance. On the other hand, those vehicles have the issue for thermal energy shortage during warming up process. The thermal energy is very large. The thermal energy seriously affect on the fuel economy for HV and the mileage for EV. In this paper, the power performance, the fuel economy and the effect of heat energy recovery from the exhaust gas are discussed for HV. For the power performance, the simulated acceleration time of 0-100km/h was 11.8sec and the measured vehicle time was 11.9sec. The error between simulation and actual measurement result was 1.2%. As for the fuel economy, the energy management using exhaust gas heat exchange system improved 10.3% of the fuel consumption during warming up.
Technical Paper

The New Toyota Inline 4-Cylinder 2.5L Gasoline Engine

In order to adapt to energy security and the changes of global-scale environment, further improvement of fuel economy and adaptation to each country’s severer exhaust gas emission regulation are required in an automotive engine. To achieve higher power performance with lower fuel consumption, the engine’s basic internal design such as an engine block and cylinder head were changed and the combustion speed was dramatically increased. Consequently, stroke-bore ratio and valve layout were optimized. Also, both flow coefficient and intake tumble ratio port were improved by adopting a laser cladded valve seat. In addition, several new technologies were adopted. The Atkinson cycle using a new Electrical VVT (Variable Valve Timing) and new combustion technology adopting new multi-hole type Direct fuel Injector (DI) improved engine power and fuel economy and reduced exhaust emissions.
Technical Paper

The New Toyota 1.2-Liter ESTEC Turbocharged Direct Injection Gasoline Engine

Toyota Motor Corporation is developing a series of engines belonging to its ESTEC (Economy with Superior Thermal Efficient Combustion) development concept. This paper describes the development of 8NR-FTS after the subsequent launch of the 2.0-liter DI Turbocharged 8AR-FTS. 8NR-FTS is a 1.2-liter inline 4-cylinder spark ignition downsized turbocharged direct injection (DI) gasoline engine. By following the same basic concepts as 8AR-FTS engine [1], the 8NR-FTS incorporates various fuel efficient technologies such as a cylinder head with an integrated exhaust manifold, the Atkinson cycle using the center-spooled variable valve timing with mid-position lock system (VVT-iW), and intensified in-cylinder turbulence to achieve high-speed combustion.
Technical Paper

The New 2.4-Liter Slant Engine, 2TZ-FE, for the Toyota Previa

This paper describes a new 2.4-liter 16-valve in-line four-cylinder engine, 2TZ-FE, which has been mounted horizontally on a new minivan, the TOYOTA PREVIA. This engine has the TOYOTA original compact 4-valve DOHC system (scissors gear mechanism), and TOYOTA's newest technologies, such as 75 deg. slant cylinder and Separated accessory Drive System. The compact configuration reduces the height of this engine to only 44Omm (17.3-inches). Engine location is under the flat floor on the midship rear-wheel-drive vehicle and allows the PREVIA to have a spacious cabin with walkthrough. Its high performance, 103kW at 500Orpm and 209Nm at 4000rpm, has been achieved through updated technologies, such as: Knock Controll System (KCS), well studied intake system and exhaust manifold which is made of stainless steel double pipe. At the same time, high reliability and quietness have been achieved for the 2TZ-FE by TOYOTA's updated technologies.
Technical Paper

The Humidity Control System Applied to Reduce Ventilation Heat Loss of HVAC Systems

Vehicles have been more required to save energy against the background of the tendency of ecology. As the result of improving efficiency of internal combustion engines and adoption of electric power train, heat loss from engine coolant, which is used to heat the cabin, decreases and consequently additional energy may be consumed to maintain thermal comfort in the passenger compartment in winter. This paper is concerned with the humidity control system that realizes reduction of ventilation heat loss by controlling recirculation rate of the HVAC system by using highly accurate humidity sensor to evaluate risk of fogging on the windshield. As the results of the control, fuel consumption of hybrid vehicles decreases and maximum range of electric vehicles increases.
Technical Paper

Study of Ignition System for Demand Voltage Reduction

Improving the engine efficiency to respond to climate change and energy security issues is strongly required. In order to improve the engine efficiency, lower fuel consumption, and enhance engine performance, OEMs have been developing high compression ratio engines and downsized turbocharged engines. However, higher compression ratio and turbocharging cause cylinder pressure to increase, which in turn increases the demand voltage for ignition. To reduce the demand voltage, a new ignition system is developed that uses a high voltage Zener diode to maintain a constant output voltage. Maintaining a constant voltage higher than the static breakdown voltage helps limit the amount of overshoot produced during the spark event. This allows discharge to occur at a lower demand voltage than with conventional spark ignition systems. The results show that the maximum reduction in demand voltage is 3.5 kV when the engine is operated at 2800 rpm and 2.6 MPa break mean effective pressure.
Technical Paper

Study of Divided Converter Catalytic System Satisfying Quick Warm up and High Heat Resistance

Catalyst specifications and converter layouts were studied to identify the high conversion performance under various in-use driving conditions, high mileage intervals and extended life cycle. The effects of volumes, configuration, selection and loading distribution of precious metals, additive components and substrate type for catalyst were studied on engine dynamometers and vehicle tests to optimize a catalyst converter system. Moreover, model gas experiments were conducted to analyze deterioration mechanisms and conversion characteristics of catalysts. As a result, the concept of a divided catalyst converter system, which provides separate functions for a close-coupled and an under-floor catalyst, was found to be effective for the future exhaust system. For reducing HC emissions, the close-coupled catalyst should warm up quickly and resist a high temperature. The under-floor catalyst, located at a rather low temperature position, is durable and maintains high NOx conversion.
Journal Article

Study of Diesel Engine System for Hybrid Vehicles

In this study, we combined a diesel engine with the Toyota Hybrid System (THS). Utilizing the functions of the THS, reducing engine friction, lowering the compression ratio, and adopting a low pressure loop exhaust gas recirculation system (LPL-EGR) were examined to achieve both low fuel consumption and low nitrogen oxides (NOx) emissions over a wide operating range. After applying this system to a test vehicle it was verified that the fuel economy greatly surpassed that of a conventional diesel engine vehicle and that NOx emissions could be reduced below the value specified in the Euro 6 regulations without DeNOx catalysts.
Technical Paper

Structural Vibration Analysis in Turbocharger-Exhaust Systems

Engine running tests and excitation tests were performed to reveal the vibration behavior in a turbocharger-exhaust system related to the turbocharger's operating sound. The operating sound was caused by the resonant vibration excited by the unbalanced inertia force of the rotor. The turbocharger-exhaust system had six resonant frequencies in the operating speed range of the rotor. At resonant speeds, the whole turbocharger was translating or rotating due to bending and torsional deflection of the exhaust manifold. Based on the test results, the vibration behavior could be well simulated by a rigid body-spring model with six degree of freedom. Furthermore, the model was used to analyze the relation between the stiffness of the exhaust manifold and the vibration level. Increasing the stiffness of the exhaust manifold was effective in sufficiently reducing the vibration and sound.
Technical Paper

Structural Design Technology for Brake Squeal Reduction Using Sensitivity Analysis

The finite element method (FEM) is effective for analyzing brake squeal phenomena. Although FEM analysis can be used to easily obtain squeal frequencies and complex vibration modes, it is difficult to identify how to modify brake structure design or contact conditions between components. Therefore, this study deals with a practical design method using sensitivity analysis to reduce brake squeal, which is capable of optimizing both the structure of components and contact conditions. A series of analysis processes that consist of modal reduction, complex eigenvalue analysis, sensitivity analysis and optimization analysis is shown and some application results are described using disk brake systems.
Technical Paper

Speciated Hydrocarbon Emissions of SI Engine During Cold Start and Warm-up

The emission characteristics of hydrocarbons during the cold start and the warm-up have been investigated. Timed sampling of hydrocarbon emissions upstream and downstream of a close-coupled catalytic converter have been carried out. The experimental results show that the emission characteristics of hydrocarbons are influenced by both the engine operating conditions and the heating characteristics of the catalytic converter. In the case of engine-out hydrocarbons, the total amount of hydrocarbons drastically decreases but the percentage contribution of the C2-C4 olefins to the engine-out hydrocarbons increases as the warm-up proceeds. Since these olefins have relatively high maximum incremental reactivity (MIR) factors, the specific reactivity (SR) of the engine-out hydrocarbons gradually increases during the warm-up. The adsorption and desorption processes of the engine-out hydrocarbons on the catalyst occur before the catalyst light-off.
Technical Paper

Silicon Nitride Swirl Lower-Chamber for High Power Turbocharged Diesel Engines

This paper describes application of sintered silicon nitride to the swirl lower-chamber in order to improve performance of turbocharged diesel engines. Various stress analyses by finite element method and stress measurements have been applied to determine the design specifications for the component, which compromise brittleness of ceramic materials. Material development was conducted to evaluate strength, fracture toughness, and thermal properties for the sintered bodies. Ceramic injection molding has been employed to fabricate components with large quantities in the present work. Quality assurance for the components can be made by reliability evaluation methods as well as non-destructive and stress loading inspections. It is found that the engine performance with ceramic component has been increased in the power out put of 9PS as compared to that of conventional engines.
Technical Paper

Road Noise Reduction Using Transfer Function Synthesis Method

An experimental simulation method has been developed for predicting the noise and vibration characteristics of a complete vehicle when body frame stiffness is changed. This method was developed by means of an improved transfer function synthesis method. Advantages over numerical simulation methods, such as finite element analysis include dramatic reductions in computation time. This experimental method is also very easy to carry out with a few measurement data. By applying this method to investigate the effects of stiffness changes of different vehicle components on low frequency road noise, effective ways of reducing road noise were proposed in the first stage of vehicle development.
Journal Article

Research into Engine Friction Reduction under Cold Conditions - Effect of Reducing Oil Leakage on Bearing Friction

Fuel efficiency improvement measures are focusing on both cold and hot conditions to help reduce CO2 emissions. Recent technological trends for improving fuel economy such as hybrid vehicles (HVs), engine start and stop systems, and variable valve systems feature expanded use of low-temperature engine operation regions. Under cold conditions (oil temperature: approximately 30°C), fuel consumption is roughly 20% greater than under hot conditions (80°C). The main cause of the increased friction under cold conditions is increased oil viscosity. This research used the motoring slipping method to measure the effect of an improved crankshaft bearing, which accounts for a high proportion of friction under cold conditions. First, the effect of clearance was investigated. Although increasing the clearance helped to decrease friction due to the oil wedge effect, greater oil leakage reduced the oil film temperature increase generated by the friction.
Technical Paper

Research and Development of a New Direct Injection Gasoline Engine

A new stratified charge combustion system has been developed for direct injection gasoline engines. The special feature of this system is employment of a thin fan-shaped fuel spray formed by a slit nozzle. The stratified mixture is produced by the combination of this fan-spray and a shell-shaped piston cavity. Both under-mixing and over-mixing of fuel in the stratified mixture is reduced by this system. This combustion system does not require distinct charge motion such as tumble or swirl, which enables intake port geometry to be simplified to improve full load performance. The effects of the new system on engine performance at part load are improved fuel consumption and reduced smoke, CO and HC emissions, obviously at medium load and medium engine speed. HC emissions at light load are also improved even with high EGR conditions.
Technical Paper

Regenration Process of Ceramic Foam Diesel-Particulate Traps

Periodic regeneration of the diesel particulate trap is essential to maintain the collection efficiency and exhaust gas hack pressure at acceptable levels. The objectives of this study are to describe the phenomenology of ceramic foam filter regeneration process and to present its mathematical model. Further simulation study is carried out to estimate the effects of various factors including fuel additive on the ignition and the filter bed temperature and to investigate conditions of excessive temperature which could result in filter destruction. The model is based on the assumption that the regeneration process is composed of two steps. The first step is the additional heat supply from the external energy source, and the second step is the spontaneous combustion propagation. The results from the analytical model agreed very well with the experimental results.
Technical Paper

Regeneration Capability of Wall-Flow Monolith Diesel Particulate Filter with Electric Heater

A regeneration of a wall-flow monolith filter with a heater unit was examined. In the preliminary test the regeneration showed unsatisfactory results, back pressure level increased and filter melting occured. Reversing the gas flow through the filter during the regeneration process and initiating particulate combustion from the outlet side of the filter was found to be a solution for the filter melting problem in particular. This “reverse regeneration” system, which we call RRG, compared with a conventional regeneration (CRG) was examined with a model reactor and applied on an actual vehicle on a chassis dynamometer. Tests confirmed that filter melting was prevented, however cracking of the filter could not be prevented with an RRG.