Search Results

Exhaust and evaporative emissions systems have been developed to match the characteristics and usage of the Toyota THS II plug-in hybrid electric vehicle (PHEV). Based on the commercially available Prius, the Toyota PHEV features an additional external charging function, which allows it to be driven as an electric vehicle (EV) in urban areas, and as an hybrid electric vehicle (HEV) in high-speed/high-load and long-distance driving situations. To reduce exhaust emissions, the conventional catalyst warm up control has been enhanced to achieve emissions performance that satisfies California's Super Ultra Low Emissions Vehicle (SULEV) standards in every state of battery charge. In addition, a heat insulating fuel vapor containment system (FVS) has been developed using a plastic fuel tank based on the assumption that such a system can reduce the diffusion of vapor inside the fuel tank and the release of fuel vapor in to the atmosphere to the maximum possible extent.

Previous reports have already described the details of engine start-shock and the mechanism of vibration mechanism in a stationary vehicle. This vibration can be reduced by optimized engine and motor generator vibration-reduction controls. A prediction method using a full-vehicle MBD model has also been developed and applied in actual vehicle development. This paper describes the outline of a new method for the hybrid system of mechanical power split device with two motors that predicts engine start-shock when the vehicle is accelerating while the engine is stopped. It also describes the results of mechanism analysis and component contribution analysis. This method targets engine start-shock caused by driving torque demand during acceleration after vehicle take-off. The hybrid control system is modeled by MATLAB/Simulink. A power management and motor generator control program used in actual vehicles is installed into the main part of the control system model.

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.

Previous studies and recent practical aerodynamic evaluations have shown that aerodynamic drag of passenger vehicles with “ground simulation” with moving ground and rotating wheels may increase in some cases and decrease in other cases relative to the fixed ground and stationary wheel conditions. Accordingly, the effects of the ground simulation on the aerodynamic drag should be deeply understood for further drag reduction. Although the previous studies demonstrated what is changed by the ground simulation, the reason for the change has not been fully understood. In this article, the effects of wheels and wheel houses attachment and those by the ground simulation with ground movement and wheel rotation on the aerodynamic drag were investigated by quantification of the underfloor flow that plays a crucially important role on the formation of vortical structure around vehicles.

Vehicles equipped with in-wheel motors are being studied and developed as a type of electric vehicle. Since these motors are attached to the suspension, a large vertical suspension reaction force is generated during driving. Based on this mechanism, this paper describes the development of a method for independently controlling roll and pitch as well as yaw using driving force distribution control at each wheel. It also details the theoretical calculation of a method for decoupling the dynamic motions. Finally, it describes the application of these 3D dynamic motion control methods to a test vehicle and the confirmation of the performance improvement.

This paper describes the development of one-piece die cast magnesium steering wheel frame for a steering wheel incorporating an air bag system. The light weight magnesium frame was designed to have proper stiffness, strength and characteristics of energy absorption. Magnesium alloys with various aluminum contents were tested, and AM60B alloy was selected because of its favorable properties of strength and elongation. New manufacturing techniques, for example, a vacuum hot chamber die casting system and a surface defect inspection system were developed in order to produce high quality castings. The characteristics of energy absorption were evaluated in the laboratory and on actual vehicle crash test, and the results were satisfactory. The magnesium steering wheel frame is about 45% (550g) lighter than the steel one. It has been in production in Toyota passenger cars with driver side air bags.

A new type of torque transmit coupling has recently been developed for 4WD cars, that provides a better match to ABS, is of lighter weight, and uses a simpler operating mechanism. This coupling transmits torque with a multi-disc clutch that is engaged by the pressure of high viscosity silicone oil. The rotary blade generates variably the silicone oil pressure, according to both differential speed and direction of rotation between the front and rear wheels. This coupling provides a good match between 4WD performance and four wheel Anti-lock Braking System (ABS) by a modification of the rotary blade shape. No additional devices are needed. This paper describes the characteristics of this coupling and the in-vehicle performance.

A new experimental method, that enables to estimate the body and driveline sensitivity to unit transmitting error of a hypoid gear for automotive rear axle gear noise, has been developed. Measurements were made by exciting the tooth of the drive-pinion gear and that of the ring gear separately using the special devices designed with regard to simulation of acceleration and deceleration. The characteristic of this method is to estimate the forces at the contact point of the gears. Estimation of these forces is carried out under the condition that the higher stiffness is provided by the tooth of the drive-pinion gear and that of the ring gear, compared with the stiffness of the driveshafts and that of the propeller shaft etc., and relative angular displacement of the torsional vibration between the teeth of the drive-pinion gear and those of the ring gear is constant.

A communication system that uses roadside beacons to broadcast road and traffic information and private messages to vehicles has been developed. The system, called Road/Automobile Communication System (RACS), was the result of a joint research project involving the Public Works Research Institute and 25 private-sector corporations. This paper contains an outline of RACS and of an onboard system developed by TOYOTA and presents the results of field tests conducted in the Tokyo area. The results not only verify the capability of the RACS system and the effectiveness of the in-vehicle equipment but also indicate the potential of such a beacon based network to improve traffic jam and driving safety whilst providing enhanced communication facilities without increasing radio-wave congestion.

The authors, et al. have succeeded in the practical application of the abradable flame spray coating, used in aircraft engines for the prevention of air leakage and the improvement of efficiency, to automobile turbochargers for the first time in the world. Two layers consisting of a bond coated layer and an abradable layer used to be coated by separate spray nozzles under the conventional technique. In this paper, equations of relations between various flame spray coating conditions and the quality of coated film, which were derived from measured results, will be described. Flame spray coating conditions, that allow the double layer coating by the same spray nozzle, have been determined for each layer. Temperatures and speeds of the flame were measured by means of two-color type high-speed cameras, and equations of their relations with the flame spray coating conditions are derived from the measured result.

Tire treadwear is a very complicated phenomenon that is influenced by various factors. Any quantitative treadwear estimating method applicable to tires on a vehicle has not yet been established. In this study the effects of acting force to the tire and tire attitude (dynamic wheel alignment) upon treadwear were made clear experimentally by taking notice of the fact that they are only the factors directly influencing tire treadwear provided that a tire and a road surface are determined. Furthermore, on the assumption that treadwear will increase linearly, an examination was made to find a method of estimating treadwear of tires on any vehicle in any running condition by using above-mentioned effects for the values of tire-acting force and dynamic wheel alignment calculated from the vehicle particular and running condition.

Hybrid vehicles (HVs) are becoming more widely used. Since HVs supplement engine drive with motor power, the lubricant oil temperature remains at a lower level than in a conventional gasoline vehicle. This study analyzed the effect of cylinder bore temperature and lubricant oil temperature on engine friction. The results showed that, although the lubricant oil temperature was not relevant, the bore temperature had significant effect on piston friction. It was found that raising the temperature of the middle section of the cylinder bore was the most effective way of reducing piston 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.

Detergent additives in automotive gasoline fuel are mainly designed to reduce deposit formation on intake valves and fuel injectors, but it has been reported that some additives may contribute to CCD formation. Therefore, a standardized bench engine test method for CCDs needs to be developed in response to industry demands. Cooperative research between the Petroleum Association of Japan (PAJ) and the Japan Automobile Manufacturers Association, Inc. (JAMA), has led to the development of a 2.2L Honda engine dynamometer-based CCD test procedure to evaluate CCDs from fuel additives. Ten automobile manufacturers, nine petroleum companies and the Petroleum Energy Center joined the project, which underwent PAJ-JAMA round robin testing. This paper describes the CCD test development activities, which include the selection of an engine and the determination of the optimum test conditions and other test criteria.

The hybrid system has the typical advantage that it can realize various types of system control, because the system has two power units, engine and motor. On the other hand, however, constraints are increasing due to the complexity of the vehicle system. Compared to the conventional HILS construction and application, there are mainly two typical characteristics or themes for HV-HILS (i.e. HILS for hybrid vehicle control development). Firstly, HV-HILS requires full vehicle simulation environment, because the plural ECU control logic is intricately intertwined. Secondly, recent HILS system needs to run with more accurate or complicated plant models which are necessary to develop more accurate vehicle control logic.

Toyota has been evolving a hybrid system since introducing the first mass-production hybrid vehicle in 1997 in response to the increasing automotive-related issues of CO2 emissions, energy security, and urban air pollution. This paper describes a newly developed hybrid system design and its performance. This system was developed with the main purpose to improve fuel consumption, especially for better real world fuel consumption; and to enhance its compatibility with multiple vehicle adoption by downsizing and reducing the weight of its components. At the same time, the hybrid system achieved improved power performance while satisfying stringent emission regulations in the world.

A full vehicle multi-body dynamic (MBD) model with suspension control system is developed for fatigue life prediction under rough road condition. The model consists of tires, a trimmed body, heavy attached parts, powertrain, suspension, joints, and a driver model, and includes a suspension control system that varies characteristics of the suspension according to the rough road inputs. For tires, a commercial MBD tire model is employed with identifiable parameters. The models are simulated to run on the optically measured road surface of the proving ground. Apart from the trimmed body, several important heavy attached parts are modeled separately, that represent dynamic behavior that induces complex body input load. These parts, along with suspension and powertrain systems are connected to the body using nonlinear elements such as joints, springs, and dampers. Contact conditions are used to represent mount bushing, hood lock, stopper rubber, etc.

Authors have developed an apparatus which measures the piston temperature using electromagnetic induction. The characteristics of this apparatus are as follows; 1 Applicable to 6 points per cylinder and all cylinders 2 Capable of measuring while the engine is running from start to 6000r/min full-load operation 3 Wide measuring range; from -30 to 400 °C 4 High accuracy; ±2.5 °C 5 Quick and easy setup 6 High durability This technology contributes to realizing the best balance of piston reliability and matching of combustion conditions. In this report, authors analyzed its influences upon piston temperature when the ignition timing,the oil/water temperature or the oil flow from piston jet were changed, respectively.

Environmental improvement is moving forward, due in part to the reduction of fuel consumption of automatic transmission(AT) vehicles as a result of social requirements in recent years and many measures have been implemented. Adoption of idling stop is a typical example introduced to reduce energy consumption while the vehicle is stopped to improve the urban environment. However, there are problems such as responsiveness and smoothness for an AT vehicle when the engine is stopped with the shift selector in “D” range. To overcome these problems, a new start clutch control system has been developed using an electric oil pump installed in a simple hybrid vehicle called a mild hybrid. As a result, a smooth feeling starting performance is achieved by operating the system in combination with the engine and other systems.

Toyota Motor Corporation developed the Fuel Cell Hybrid Vehicle (FCHV). The FCHV-4 is an evolution of the conventional fuel cell vehicle that has made immense improvements in efficiency. Both a fuel cell and a secondary battery are used as sources of energy for the hybrid system. By using these energy sources proportionally, the system can be kept at or near its optimum state. The FCHV-4's system is designed to improve the efficiency and aims for high responsiveness when the vehicle is in a transitional state. In the same way as most electric vehicles, and as in the gasoline powered hybrid “Prius”, the energy the traction motor creates during breaking can be used to regenerate the secondary. The fuel cell and traction motor inverter are connected directly, with the secondary battery connected through the DC/DC converter to the fuel cell in parallel.