Search Results

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.

Oil film thickness is one of the most important issues for optimization of bearing design. A technique has been developed to measure oil film thickness by noting the change in capacitance between the shaft and a thin-film electrode of several micrometers thickness formed on the surface of a bearing. The authors applied this technique to the main journals of an automobile engine and measured the oil film thickness up to maximum speed and full load. The oil film thickness became thinner with increased engine load, and then turned thicker with increased engine speed.

An on-board particulate matter (PM) sensor, consisting of a gas-permeable electrochemical cell with a porous yttria-stabilized zirconia solid oxide electrolyte, was developed to assist the on-board diagnostics (OBD) system of a vehicle. Exhaust is pumped from the anode side to the cathode side and PM deposited on the anode is instantly oxidized by the catalytic effects of the metal component of the electrode at temperatures higher than 350°C. The PM oxidation reaction occurs at the three-phase boundary between the anode, electrolyte and gas phase, and causes a slight change in the bulk average oxygen concentration, which produces electrochemical polarization by the difference in oxygen partial pressures between the anode and cathode. The developed PM sensor has a detection limit of 2 mg/m₃, at which level will enable PM detection in the OBD system according to the EURO VI regulation.

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.

Model based control design is an important method for optimizing engine operating conditions so as to simultaneously improve engines' thermal efficiency and emission profiles. Modeling of intake system that includes an intake throttle valve, an EGR valve and a variable geometry turbocharger was constructed based on conservation laws combined with maps. Calculated results were examined the predictive accuracy of fresh charge mass flow, EGR rate and boost pressure.

This paper describes the development of a High Speed Calculation Diesel Combustion Model that predicts combustion-related behaviors of diesel engines from passenger cars. Its output is dependent on the engine's operating parameters and on input from on-board pressure and temperature sensors. The model was found to be capable of predicting the engine's in-cylinder pressure, rate of heat release, and NOx emissions with a high degree of accuracy under a wide range of operating conditions at a reasonable computational cost. The construction of this model represents an important preliminary step towards the development of an integrated Model Based Control system for controlling combustion in diesel engines used in passenger cars.

A new method to measure in-cylinder flame propagation and mixture distribution has been developed. The distribution is derived from analyzing the temporal history of flame spectra of CH* and C2*, which are detected by a spark plug type sensor with multi-optical fibers. The validity of this method was confirmed by verifying that the measurement results corresponded with the results of high speed flame visualization and laser induced fluorescence (LIF) measurement. This method was also applied to analysis of cyclic combustion fluctuation on start-up in a direct injection spark ignition (DISI) engine, and its applicability was confirmed.

The efficiency of the NOx Storage and Reduction (NSR) catalysts used in the aftertreatment of diesel engine exhaust gases can potentially be increased by using reactive reductants such as CO and H₂ that are formed during in-cylinder combustion. In this study, a multi-dimensional computational fluid dynamics (CFD) code coupled with complex chemical analysis was used to study combustion with various fuel after-injection patterns. The results obtained will be useful in designing fuel injection strategies for the efficient formation of CO.

Requirements to reduce emissions and improve vehicle fuel economy continue to increase, spurred on by agreements such as the Kyoto Protocol. Lubricants can play a role in improving fuel economy, as evidenced by the rise in the number of engine oil specifications worldwide that require fuel economy improvements. A novel friction modifier technology has been developed to further improve vehicle fuel economy. The development of this novel friction modifier technology which contains only N,O,C,H was previously published along with the initial demonstration of performance in motorized Toyota engines. In order to validate this performance in fired engine tests, oil was evaluated in a Toyota Corolla Fielder with a 1500 cc gasoline engine. Testing was conducted in the Japanese 10-15 and JC08 modes, as well as the European EC mode, and the US FTP mode.

It may be possible to simplify the structure and control systems of a lithium-ion battery by replacing the conventional liquid electrolyte with a solid electrolyte, resulting in higher energy density. However, power performance is a development issue of batteries using a solid electrolyte. To increase battery power performance, in addition to lithium ionic conductivity within the bulk of the electrolyte, it is also necessary to boost the lithium ionic conductivity at the interface between the electrode active material and the electrolyte, and to boost electron and lithium ionic conductivity within the cathode and anode active material. This research studied the mechanism of resistance reduction by electrode surface modification. Subsequently, this research attempted to improve electron conductivity by simultaneously introducing oxygen vacancies and carrying out nitrogen substitution in the crystalline structure of the Li4Ti5O12 anode active material.

The outline of the TOYOTA FCHV-adv is described in this paper. The TOYOTA FCHVadv achieved an approximately 25 percent improvement in vehicle fuel efficiency and about 1.9 times the amount of usable hydrogen in comparison with the previous model. These improvements have enabled almost 2.5 times longer practical cruising range, more than 500 km. The freeze start capabilities of the FCHV-adv were improved by modifying the FC stack and control system. As a result, the FCHV-adv has been capable of starting at a temperature of -30°C. In the future, TOYOTA intends to improve durability and reduce costs.

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.

An IGBT model for use in circuit simulations (called the “HiSIM-IGBT model” below) has been developed that can be applied to the design of electrical characteristics occurring in accordance with the complex control methods adopted by the power converters of electric and hybrid vehicles. Since the HiSIM-IGBT model expresses carrier behavior inside the IGBT with physical formulas, electrical characteristics can be simulated with high accuracy, enabling very precise and rapid design of electrical characteristics using IGBTs.

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.

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.

Diesel engines with relatively good fuel economy are known as an effective means of reducing CO₂ emissions. It is expected that diesel engines will continue to expand as efforts to slow global warming are intensified. Diesel particulate and NOx reduction system (DPNR), which was first developed in 2003 for introduction in the Japanese and European markets, shows high purification performance which can meet more stringent regulations in the future. However, it is poisoned by sulfur components in exhaust gas derived from fuel and lubricant. We then developed the sulfur trap DPNR with a sulfur trap catalyst that traps sulfur components in the exhaust gas. High purification performance could be achieved with a small amount of platinum group metal (PGM) due to prevention of sulfur poisoning and thermal deterioration.

Model-Based Development (MBD) has become an automotive industry standard process in vehicle control systems development due to the potential to reduce development time and improve engineering quality. This has become even more important as control systems are becoming increasingly complex while development cycle timelines shorten. Toyota utilized Hardware-in-the-Loop Simulations (HILS) techniques when developing the latest Fuel Cell Hybrid Vehicle, FCHV-adv. These MBD techniques contributed to the overall development process, but applications were limited to verifying control specifications. It was recognized that if MBD could be utilized beyond its current role in the control system design process to include functional specification validation, specification quality could be improved while decreasing development time and cost.

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.

Technologies of 4WD chassis dynamometers (CHDY hereinafter) have advanced dramatically over the past several years, enabling 4WD vehicles to be tested without modifying their drive-train into 2WD. These advances have opened the use of 4WD-CHDY in all fuel economy and emission evaluation tests. In this paper, factors that influence the accuracy of fuel economy tests on 4WD CHDY are discussed. Fuel economy tests were conducted on 4WD CHDY and we found that most of the vehicle mechanical loss is the tire loss and that stabilizing the tire loss of the test vehicle is essential for the test reproducibility.

Mass reduction of parts is growing in importance as a means for reducing CO2 emissions from vehicles.The aim of the present research was to contribute to further mass reduction of pistons by developing a new aluminum casting material with highest level of fatigue strength. This goal was achieved using a development concept of creating a homogeneous structure in which Ti was added to create a fine structure and appropriate quantities of Fe and Mn were added to form a compound that is stable at high temperatures. Stand-alone tests of prototype pistons fabricated using the developed material show that the material is 14% stronger than the conventional material, thereby enabling increases in power and mass reduction.