Search Results

A compact and high-performance five-speed automatic transmission(A350E) has been developed for passenger cars. The development of this transmission has been aimed at improvement in acceleration performance in the low and medium speed range and at smooth acceleration. A five-speed automatic transmission with a simple gear train has been completed by means of the industry's first modern control theory aided shifting technique.

Toyota has developed a new full time 4WD system, called “EC-HYMATIC” or Electronically Controlled - HYdraulic Multi-plate clutch Active Traction Intelligent Control. This system permits an automatic torque transfer, depending on driving conditions, for front and rear wheels under control of the speed difference between the two. The system developed consists of a center differential, a speed difference control clutch system employing multi-plate clutch, and a gear set for rear axle drive. The speed difference control clutch system is controlled by a unique electro-hydraulic system using a microcomputer. An extensive use of computer simulations and vehicle test and evaluation has successfully developed an appropriate control strategy for the clutch system. The new 4WD system, EC-HYMATIC, considerably improves handling characteristics, traction performance and stability of a 4WD vehicle.

Lean mixture operation and high transient response has been accomplished by the introduction of newly designed Central Injection (Ci) system. This paper describes the effects of Ci design variables on its performance. Lean mixture operation has been attained by optimizing the injection interval, injection timing and fuel spray angle in order to improve the cylinder to cylinder air-fuel ratio distribution. Both air-fuel distribution and transient engine response are affected by the fuel spray angle. Widening the fuel spray angle improves the air-fuel distribution but worsen the transient engine response. This inconsistency has been solved by off-setting the injector away from the center axis of the throttle body and optimizing the fuel spray angle.

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.

This paper describes a simulation study of the internal fluid flow of a torque converter. The study was conducted by using the steady-interaction technique to connect the boundaries between neighboring elements. This technique averages the flow variables in the circumferential direction on the connecting boundary surfaces. A comparison of computational results with experimental data gives an estimate of the accuracy in predicting torque converter performance with this method.

The automobile industry currently faces many challenges which may greatly impact on its foundry operations. One of these challenges, consumers'' demand for greater fuel efficiency, can be met by reducing the weight of castings used in automobiles, and minimizing engineering tolerances. In answer to this particular demand, engine foundries have begun to either produce cylinder blocks or other castings with aluminum rather than cast iron. However, if a reduction in weight (thin wall and near-net shaping) can be realized with cast iron, there would be numerous merits from the perspective of cost and compactness and there would be much more flexibility in automotive parts design.

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 an analysis of the rise in timing belt temperature occuring under high engine speed operation that was made to establish the cause of heat deterioration of the belt materials. Surface temperatures of the belt were accurately measured by correcting thermo-vision detected radiations to eliminate environmental radiation. The temperature profile of a belt cross-section was obtained by a specially developed thermo-couple device. The experimental results indicated that heat generated by the belt contributes significantly to the temperature rise and that the primary cause of the heat generation is bending hysteresis of the belt cords. In addition, a description is made of a method of calculating the rate of heat generation in the belt. In this simulation method, the energy dissipated as heat is calculated from the bending strains and loss moduli of the belt materials. Calculated results were found to agree well with experimental results.

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.

We have developed a method by which the oil flow rate can be measured by using a hot-wire sensor that could be installed in the passages of actual engine lubricant oil. This measuring method proves to have a ±5% accuracy and a 40kHz response that enables ‘real time’ function. Thus, observation of (1) the effect of bearing clearance, and (2) the fluctuating mechanism of the oil flow per 1 degree crank angle from the point of engine start-up to 6000r/min and full load can be achieved, and the timing and quantity of intermittent oil-jet from the oil hole in connecting rod were ascertained.

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.

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.

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.

In many countries, cetane number and distillation properties of diesel fuel have been changing, thus affecting the performance of diesel engines. This paper describes investigations made on the effect of diesel fuel quality on white smoke (one of the important emissions of diesel engines). The result of simple laboratory tests simulating high altitude conditions plus field tests using three types of disel engines supplied with various types of diesel fuels is given. It was found that white smoke appearing tendency correlated best with cetane number and the 90 percent distillation point of the fuel. The field tests performed at high altitude correlated well with the simple laboratory tests.

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.

Bio-hydro fined diesel (BHD) oil is known as a second generation oil made from bio hydro finning process. Biodiesel in the first generation is made from transesterification process and it has several disadvantages such as high density and increased the viscosity that can cause operational problems because can make some deposits in the engine. To overcome this, the second generation process of biodiesel has been modified from the first generation oil. BHD is made from the waste cooking oil by using the hydro finning process without the trans-esterification process. The results of BHD oil has nearly the same with diesel oil. BHD oil has low viscosity and high oxidation stability. Therefore, BHD oil can be used in the diesel engine without making any modifications in the engine. In this study, the comparison of performance and emissions characteristics from BHD oil, waste cooking oil, and diesel oil are investigated.

It has been demonstrated that the in-cylinder turbulence of a 4 valve engine with a swirl control valve (SCV) is enhanced by inclined swirl. This paper examines the effects on turbulence of varying swirl inclination angle defined as the inverse tangent of the vertical component of total angular momentum divided by the horizontal component. Experiments were conducted on a 4-valve single cylinder engine with SCV using a backward-scatter LDV and BSA (Burst Spectrum Analyzer). The results show that although total angular momentum is greatest with horizontal swirl, turbulence intensity measured in the center of the combustion chamber attains a peak value when the swirl inclination angle is between 30 and 45 degrees from the cylinder axis under the same air flow rate.

The effects of diesel fuel properties (aromatic content, cetane index and T90), cetane improver, oxygenates, high boiling point hydrocarbons and aromatics distribution on diesel exhaust emissions were studied under the Japanese 10-15 test cycle and the ECE+EUDC test cycle. The test vehicle was a TOYOTA COROLLA with a natural aspirated, 2.0L displacement, IDI diesel engine. It was demonstrated that particulate emissions are highly correlated with T90 and that NOx is affected by the aromatic content of fuel. A reduction in particulates emissions was observed in fuel with a lower cetane number by adding cetane improver, but this reduction was limited. Cetane improver had no effect on NOx emissions in the 45 # 60 cetane number range. Oxygenates reduced particulate emissions remarkably but had little effect on NOx emissions. A decrease in the soot in particulates was particularly observed.

Turbocharged (TC) engines have been introduced these days to improve the fuel economy. It is considered that one possible issue of the TC engine is a pre-ignition at high engine speed because of high temperature and high pressure in the combustion chamber. This study shows the effect of fuel compounds on pre-ignition at 4400rpm. The experimental engine is a naturally-aspirated (NA) engine which is customized to imitate the cylinder temperature and pressure of TC engines. It is known that research octane number (RON) describes anti-knock quality well. Meanwhile the results show that pre-ignition characteristic at high engine speed is dominated by motor octane number (MON) and auto-ignition temperature (AIT) rather than RON.