Search Results

Although idling vibration is usually caused by 1st order of engine combustion force, other engine forces also occur at frequencies lower than the 1st order of combustion (called low frequency idling vibration in this paper). The drive-line of the Toyota Hybrid System II (THS II) has different torsional vibration characteristics compared to a conventional gasoline engine vehicle with an automatic transmission. Nonlinear characteristics caused by the state of backlash of pinions and splines influence changes in the torsional resonance frequency. The torsional resonance frequency of the drive-line can be controlled utilizing the hybrid system controls of the THS II.

The aim of this work is to investigate the possibility of heat insulation by “Temperature Swing”, that is temperature fluctuation, on combustion chamber walls coated with low-heat-conductivity and low-heat-capacity materials. Adiabatic engines studied in the 1980s, such as ceramic coated engines, caused constantly high temperature on combustion wall surface during the whole cycle including the intake stroke, even if it employed ceramic thermal barrier coating methods. This resulted in increase in NOx and Soot, decrease in volumetric efficiency and combustion efficiency, and facilitated the occurrence of engine knock. On the other hand, “Temperature Swing” coat on the combustion chamber walls leads to a large change in surface temperature. In this case, the surface temperature with this insulation coat follows the transient gas temperature, which decreases heat loss with the prevention of intake air heating, and also which is expected to prevent NOx and Soot from increasing.

Computational fluid dynamics (CFD) shape optimization technology is playing an increasingly significant role in the development of products that satisfy various demands, including trade-off relationships. It offers the possibility of designing or improving product shape with respect to a given cost function, subject to geometrical constraints. However, conventional CFD shape optimization technology that uses parametric shape modification has two following issues: (1) expensive computational cost to obtain the final shape, (2) performance variations of the obtained shape depends on the skill or experience of the designer who determined the locations to be modified. In this study, to resolve those problems, an efficient shape optimization technology was developed that uses the adjoint method to perform sensitivity analysis of a cost function on the design parameters. It is composed of a combination of topology optimization and surface geometry optimization.

It has been long established fact that fuel economy is a key driving force of low viscosity gasoline engine oil research and development considered by the original equipment manufacturers (OEMs) and lubricant companies. The development of low viscosity gasoline engine oils should not only focus on fuel economy improvement, but also on the low speed pre-ignition (LSPI) prevention property. In previous LSPI prevention literatures, the necessity of applying Ca/Mg-based detergents system in the engine oil formulations was proposed. In this paper, we adopted a specific Group III base oil containing Ca-salicylate detergent, borated dispersant, Mo-DTC in the formulation and investigated the various effects of Mg-salicylate and Mg-sulfonate on the performance of engine oil. It was found that Mg-sulfonate showed a significant detrimental impact on silicone rubber compatibility while the influence from Mg-salicylate remains acceptable.

A newly developed AR series 4-cylinder engine has achieved high fuel efficiency through the following: adopting roller rocker arms for the valvetrain system and a variable output oil pump to reduce the friction losses, optimizing the combustion chamber and its cooling system for high compression ratio, and adopting VVT-i (Variable Valve Timing-intelligent) for both intake and exhaust camshafts to enhance thermal efficiency of the engine. Engine torque has been enhanced across the entire range of engine speeds while high performance at low engine speed is achieved by adopting a variable induction intake manifold system (ACIS-III). Output power has been enhanced by making the intake and exhaust systems highly efficient. A hinge type tumble control valves were developed to improve emissions at low temperature by improving combustion when the engine is cold in order to comply with the U.S. Cold-NMHC.

Objective: Opposite-direction crashes can be extremely severe because opposing vehicles often have high relative speeds. The most common opposite direction crash scenario occurs when a driver departs their lane driving over the centerline and impacts a vehicle traveling in the opposite direction. This cross-centerline crash mode accounts for only 4% of all non-junction non-interchange crashes but 25% of serious injury crashes of the same type. One potential solution to this problem is the Lane Departure Warning (LDW) system which can monitor the position of the vehicle and provide a warning to the driver if they detect the vehicle is moving out of the lane. The objective of this study was to determine the potential benefits of deploying LDW systems fleet-wide for avoidance of cross-centerline crashes. Methods: In order to estimate the potential benefits of LDW for reduction of cross-centerline crashes, a comprehensive crash simulation model was developed.

Down-sizing and dielectric insulation were required for the traction motors of hybrid vehicles. By utilizing the newly developed coil with thick resin insulation atop the conventional enamel film, the use of conventional inter-phase insulation paper was abolished. Furthermore, by adopting the stair-shaped coil structure and spiral winding configuration, the stator size was minimized. With the above technologies, the motor installation to smaller hybrid vehicles was realized, thus contributing to weight reduction of hybrid vehicles.

We develop a new metal-belt continuously variable transmission fluid (CVTF) named FE to improve fuel economy and help reduce CO2 emissions. FE is a low-viscosity fluid that reduces friction loss at low temperatures. Low-viscosity fluids generally reduce hardware durability, resulting in reduced metal fatigue life. Therefore, FE is designed for maintaining oil film thickness throughout the life of a vehicle by optimizing the base oil and viscosity modifier. FE also exhibits long-term anti-shudder performance that enables frequent use of controlled-slip torque converter clutches for improving fuel economy, represented by the flex start system, without decreasing torque capacity between the belt and pulley. The key point in the formulation of design is the selection of a suitable friction modifier. A friction modifier is an additive that improves friction properties.

After the Great East Japan Earthquake on March 11, 2011, Toyota Motor Corporation received considerable public response regarding the role of vehicles in emergencies from a large number of customers. These included comments about the usefulness of the electricity supply system in the Estima Hybrid during the long power outages caused by the earthquake. In response, Toyota decided to install this system in its other hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs). This system is capable of supplying power up to 1,500 watts, which means that it can be used to operate virtually every household electrical device. Since the engine starts automatically when the main battery capacity is depleted, a single vehicle can supply the daily power needs of a normal house in Japan for about four days, providing that the battery is fully charged and the fuel tank is full.

Reducing powertrain losses is an important technical challenge to further improve the efficiency of electric vehicles as part of measures toward achieving carbon neutrality. One effective method of accomplishing this goal is to reduce the viscosity of transaxle lubricating oil. However, it is generally known that lowering viscosity can cause durability issues such as wear and seizure if the thickness of the lubricating oil film on metal sliding surfaces is insufficient. In gears and bearings, reducing the oil film thickness can increase direct contact with the base metal and may cause surface fatigue peeling. A new additive formulation for lubricating oil specifically for electrified vehicles has been designed in anticipation of the wider adoption of such vehicles in the future. The result has been a new transaxle fluid that ensures unit durability while reducing viscosity of 40°C to 12.2[mm2/sec].

Recently, diesel engine manufacturers have been improving the tolerance of fuel injection quantity and timing in response to the strengthening of emissions regulations and the introduction of various kinds of diesel fuels. This paper describes the Intelligent Accuracy Refinement Technology (i-ART) system, which has been developed as a way of achieving substantially improved tolerances. The i-ART system consists of a fuel pressure sensor installed in the injectors. It calculates the injection quantity and timing at high speed using a dedicated microcomputer designed for pressure waveform analysis. As the injector can directly measure the fuel injection pressure waveform for each injection, it can compensate the injection quantity and timing tolerance at any time. Toyota Motor Corporation has introduced this system in Brazilian market vehicles. In Brazil, the PROCONVE L6 emissions regulations will be introduced in 2012, and the market also uses various kinds of diesel fuels.

An investigation was made into the effects of valve lifter material on fuel consumption and engine noise. It was found that the use of aluminum not only improves fuel economy but also reduces valve-train chatter because it is lighter in weight and less hard than steel. The stresses to which the valve lifters are subjected and their surface temperatures were measured in bench tests, and durability tests were conducted to ascertain the problems which might be expected. Based on the results of these tests, the shape was modified, a new aluminum alloy was developed and a coating was applied to the surface. The aluminum valve lifters thus developed were found to be as durable as conventional steel lifters and have been used in the new Toyota V8 engine (IUZ type).

We have developed a new automotive instrument cluster consisting of a dial made of a glossy natural metal in order to enhance the high-quality appearance of the cluster. The glass covering the cluster contains an electrochromic device (ECD) to reduce the glare of natural light reflecting off the dial. The ECD automatically controls light transmittance in steps based on the brightness of the surrounding environment. We had to solve the following two problems before successfully completing the new cluster development: (1) Selection of a transparent device that can change the light transmittance; and (2) Finding a method for sensing the intensity of sunlight reflected from the dial surface.

Three improvements for the Hybrid III dummy parts are proposed by NHTSA, they are the neck shield, hip joint, and ankle joint In this paper, two modifications of the three, the neck shield and hip joint, are evaluated The recommended neck shield was tested and compared to the previous type to investigate the following, 1 The effect of the neck moment on both the recommended and previous type, and 2 The comparison between the stiffness of the neck shield and human soft tissue under the chin, using a volunteer static test From these tests, the new recommended neck shield performed better than the previous type with respect to both biofidelity and the effect on the neck moment test The neck shield for 5th-percentile female was also considered The hip joint recommended by NHTSA was compared with the modified joint and pelvis proposed by Toyota It was found that the NHTSA's recommended hip joint eliminated the hip lock due to metal-to-metal contact It was also found that the maximum rotation angle of the NHTSA's recommended hip joint was less than that of the hip joint and pelvis proposed by Toyota

For low frequency brake squeal (1-3kHz) anti-squeal shims are not always effective Development of an appropriate reduction method is therefore an important issue Theoretical analysis of low-frequency squeal has been shown by many papers But presently the squeal reduction method is not sufficient for vehicles In this study we measured brake component frequency response during brake application with stabilized friction surface condition This method enabled us to find the optimal rotor natural frequency and reduce low-frequency brake squeal

Toyota introduced a new engine control system using a new microprocessor during the Fall of 1982. The new control system is used effectively for more complex application to engine and automatic transmission control. It controls air-fuel ratios in combination with the transmission shift control to achieve good fuel economy, driveability, as well as emission reduction. This system includes a self diagnostic capability, in which the electronic control unit (ECU) diagnoses system abnormalities, stores them in the memory and turn on the CHECK ENGINE lamp. To assure the proper system operation against any failure of the processor, the electronic control unit has a back up circuit which executes the predeterminded operation of fuel injection and spark timing. For this system, a new 12-bit microprocessor capable of high speed real time processing was developed.

Arc welding lines have many quality assurance processes which should rely upon manual work, but high efficiency could not be obtained even if welding robots are introduced alone. The authors developed a new welding torch and automatic tool exchanger system. Through these developments, doubled productivity and a thirty percent cost reduction could be attained compared with the previous arc welding robot lines.

A new variable venturi carburetor has been developed, in order to achieve high metering accuracy, fuel economy, higher power and good driveability of the vehicle. This carburetor is a down-draft-type, and has better characteristics compared with the fixed venturi carburetor, such as better fuel atomization, lower cycle-to-cycle variation of combustion in lean mixture, faster response, and higher power. For this carburetor, a new type venturi and a new cold enrichment system has been developed. This venturi type has an exponential-profile with a nearly constant increasing rate of venturi opening area to the suction piston stroke. The new cold enrichment system controls the airfuel ratio in all conditions by changing air bleed quantities using the thermo-wax. With this system, cold drive-ability is improved greatly.

Higher compression ratio and lower air-fuel ratio tend to raise the required break down voltage. Various types of electrode configurations were examined. It was found that a very thin platinum plate attached to each elect-rode was effective in reducing the electrode wear. This newly developed platinum tipped spark plug uses a small sized center electrode and an enlarged initial spark gap. The lean misfire limit and the torque fluctuation at partial load are improved with the platinum tipped spark plug. After a durability test, the break down voltage became lower due to the grained platinum surface. The spark gap was almost unchanged during an 80 thousand kilometer durability test run.

The lean combustion of an SI engine has been recognized as one of the most promising methods for further improvement of fuel economy. There has been, however, difficulty in extending the lean misfire limit enough to realize NOx emission levels below the mandatory level and still keep satisfactory driveability. A simulation study has been carried out to search for the possibility of getting better fuel economy under the constrainsts of NOx emission and driveability. To realize the optimum calibration, the lean misfire limit has been extended by the introduction of (1) high swirl and high combustion chamber turbulence through the use of a helical port with an unique swirl control valve, (2) a newly developed ZrO2 lean mixture sensor and (3) the multi-point fuel injection with sophisticated control. A very good fuel economy level of 17.0 km/1 (Japanese 10 mode) has been accomplished while still meeting the NOx emission cycle regulation of 0.25 g/km.