Search Results

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.

This paper presents a custom integrated circuit (IC) on which circuit functions necessary for “Active Hydraulic Brake (AHB) system” are integrated, and its key component, “Current-to-Digital Converter” for solenoid current measurement. The AHB system, which realizes a seamless brake feeling for Antilock Brake System (ABS) and Regenerative Brake Cooperative Control of Hybrid Vehicle, and the custom IC are installed in the 4th-generation Prius released in 2015. In the AHB system, as linear solenoid valves are used for hydraulic brake pressure control, high-resolution and high-speed sensing of solenoid current with ripple components due to pulse width modulation (PWM) is one of the key technologies. The proposed current-to-digital converter directly samples the drain-source voltage of the sensing DMOS (double-diffused MOSFET) with an analog-to-digital (A/D) converter (ADC) on the IC, and digitizes it.

In order to correspond to the exhaust emissions regulations that become severe every year, more advanced engine control becomes necessary. Engine engineers are concerned about the Hydrocarbons (HCs) that flow through the air-intake ports and that are difficult to precisely control. The main sources of the HCs are, the canister purge, PCV, back-flow gas through the intake valves, and Air / Fuel ratio (A/F) may be aggravated when they flow into the combustion chambers. The influences HCs give on the A/F may also grow even greater, which is due to the increasingly stringent EVAP emission regulations, by more effective ventilation in the crankcase, and also by the growth of the VVT-operated angle and timing, respectively. In order to control the A/F more correctly, it is important to estimate the amount of HCs that are difficult to manage, and seek for suitable controls over fuel injection and so on.

Non-equilibrium all-atom MD simulations are used to study the traction properties of hydrocarbon fluids. A fluid layer is confined between two solid Fe plates under the constant normal force of 1.0 GPa. Traction simulations are performed by applying a relative sliding motion to the Fe plates. Shear behaviors of nine hydrocarbon fluids are simulated on a sufficiently large film thickness of 6.7 nm, and succeeded in reproducing the order of the experimental traction coefficients. The dynamic mechanism of the momentum transfer on layers of fluid molecules are analyzed focusing on the intermolecular interactions (density profile, orientation factor, pair-correlation function) and intramolecular interactions (intramolecular interaction energy, conformation change of alicyclic ring). In contrast to the case of n-hexane, which shows low traction due to a fragile chain-like interaction, other mechanisms are obtained in the high traction molecules of cyclohexane, dicyclohexyl and santotrac 50.

A multi-dimensional numerical method for predicting the warm-up characteristic of automobile catalytic converter systems was developed to effectively design catalytic converter systems which achieve low tail pipe emissions with satisfactory packagebility. The features of the method are; (1) consideration of the governing phenomena such as gas flow, heat transfer, and chemical reactions (2) capability of predicting warm-up characteristic for not only the catalytic converters but also the system as a whole during emission test modes such as the USA LA-4 mode. The description of the method is presented. The experimental verifications of the method were conducted to assure the accuracy of it. The effect of design parameters such as electrically heated catalyst (EHC), high loading of noble metal and thin honeycomb wall on warm-up characteristic of the catalyst are analyzed in the paper.

A new 4.5 liter in-line 6 cylinder engine,1 FZ-FE has been developed for the Toyota Land Cruiser. To obtain high power, fuel efficient engine, we adopted the most advanced Toyota technologies, such as Toyota original 4 Valve DOHC system with scissors gear between camshafts, compact combustion chamber with smooth inlet and outlet system, KCS and so on. The engine produces 212 HP at 4600 rpm and 275 ft-lbs at 3200 rpm. Aluminum cylinder head,short skirt cylinder block stiffened with aluminum oil pan give the engine light weight and make it rigid enough to have low vibration and quietness. And we also designed every engine part appropriately so as to make the engine durable enough in severe operating condition of off-road vehicle.

A new material recycling technology for crosslinked rubber was developed using the continuous reactive processing method. In this process of producing reclaimed rubber, breakage of crosslinking points in the crosslinked rubber occurs selectively under the controls of shear stress, reaction temperature, and internal pressure in a modular screw type reactor. Deodorization during the process has also become possible by a newly developed method. The reclaimed rubber obtained from rubber waste generated from both automobile manufacturing products and post-consumer products shows excellent mechanical properties applicable to new rubber compounds. Furthermore, an enhanced rubber recycling process for producing thermoplastic elastomer (TPE) based on rubber waste has been established. The obtained TPE exhibits highly recoverable rubber elasticity and mechanical properties comparable to commercial TPE.

In SI engines with port injection system, fuel behavior both in the intake port and in the cylinder has significant influence on the transient A/F characteristics and HC emissions [1]. Therefore, to improve the engine performance, it is very important to understand fuel behavior in the intake port and in the cylinder [2, 3]. This paper describes the following three unique methods to analyze fuel behavior in port injected SI engines and some test results. (1) Observation of fuel behavior in the intake port, using a transparent intake air tube and a strobe synchronized TV-photographic system. (2) Observation of fuel behavior in the cylinder, using a glass cylinder and fluorescent fuel. (3) Measurement of fuel wall wetting in the intake port and in the cylinder, using the engine with electronically controlled hydraulically driven in-take/exhaust valves.

A new proportional collection system for extremely low tailpipe emission measurement in transient conditions has been developed. The new system can continuously sample a minute flow of exhaust gas, at a rate that is proportional to the engine exhaust rate. A zero grade gas dilution technique is utilized to prevent the influence of pollutants in atmospheric air that are the same concentration level as those in the exhaust gas. The system has accuracy within ±5%. For the direct exhaust gas flow meter, a pitot tube type flow meter is utilized as it is simple, heat resistant, sufficiently accurate and has low flow-resistance characteristic. For the collection and dilution controllers, two mass flow controllers (MFC) were adopted. The MFCs' output can be adversely influenced by variation of the specific heat of the sample gas, resulting in flow reporting error.

A new 4.0 liter V8 engine, 1UZ-FE, has been developed for the luxury sedan, LEXUS LS400. The engine has 4 camshafts and 32 valves, and weighs only 195 kg (430 lbs) having many light alloy components and carefully designed configurations. The appropriate engine displacement and high technology adopted throughout from design to manufacturing process enable the LS400 to run powerfully with excellent fuel economy and a pleasant sounds. It develops 250HP at 5600 rpm and 260ft-lbs of torque at 4400 rpm, and its fuel economy figure, well exceeds the EPA's tax charge level of 22.5mpg. These figures have been achieved through the newest technologies applied to every part of the design, such as: Well studied intake and exhaust systems, centrally located spark plug in the TOYOTA original four-valve combustion chamber, which has a narrow valve including angle, and low friction components like aluminum alloy valve lifters and well balanced moving parts.

The particle number (PN) emission regulation has been implemented since 2011 in Europe. PN measurement procedure defined in ECE regulation No. 83 requires detecting only solid particles by eliminating volatile particles, the concentrations of which are highly influenced by dilution conditions, using a volatile particle remover (VPR). To measure PN concentration after the VPR, a particle number counter (PNC) which has detection threshold at a particle size of 23 nm is used, because most solid particles generated by automotive engines are considered to be larger than 23 nm. On the other hand, several studies have reported the existence of solid and volatile particles smaller than 23 nm in engine exhaust. This paper describes investigation into a measurement method for ultrafine PNCs with thresholds of below 23 nm and evaluation of the VPR performance for the particles in this size range. The detection efficiency of an ultrafine PNC was verified by following the ECE regulation procedure.

In the initial design stage, it is important to discuss what kind of body concept is effective from a viewpoint of environment burden reduction. This paper describes the importance of both weight reduction and recycling through conducting LCA (Life Cycle Assessment) for four kinds of body structures. In addition, using each software, DFMA (Design for Manufacture and Assembly), DFE (Design for Environment) and LCA to parts unit, each effectiveness was discussed through the assessment of the material-hybrid body.

Recently, the role of ECU(Electronic Control Unit) on vehicles has been becoming more important year by year in order to meet the requirements for safety and the environmental matters. Particularly, the ECU of Engine Management Systems has been becoming indispensable in order to realize high performance, low fuel consumption and low exhaust emission. Therefore, the size of software has also been increasing, and been becoming more complex and complicated. As the ECU software size becomes large and complex, the verification and validation of the software by using the current development method has been becoming more difficult. Especially it has been becoming more difficult to validate the Real-time property of the software. The Real-time property means whether the execution of the software is in time for the deadline which is decided on the software design.

Electric drive vehicles (EDV) have the potential to greatly reduce greenhouse gas (GHG) emissions and thus, there are many policies in place to encourage the purchase and use of gasoline-hybrid, battery, plug-in hybrid, and fuel cell electric vehicles. But not all vehicles are the same, and households use vehicles in very different ways. What if policies took these differences into consideration with the goal of further reducing GHG emissions? This paper attempts to answer two questions: i) are there certain households that, by switching from a conventional vehicle to an EDV, would result in a comparatively large GHG reduction (as compared to other households making that switch), and, if so, ii) how large is the difference in GHG reductions? The paper considers over 65,000 actual GPS trip traces (generated by one-second interval recording of the speed of approximately 2,900 vehicles) collected by the 2013 California Household Travel Survey (CHTS).

The characteristics of exhausted smoke of a methanol DI diesel engine which is ignited by diesel fuel are investigated to clarify the soot formation process. At this engine, very little smoke is exhausted when diesel fuel is kept below a certain amount, so soot and smoke emitting characteristics are studied under the various diesel fuel amounts. By analyzing microstructure of soot, it is found that the soot emitted from the methanol diesel engine is composed of inner core and outer shell, similar to that of the conventional diesel engines. From more detailed qualitative analysis, the calcium percentage from the lubricating oil in outer shell is much higher than that of the conventional diesel engines. In consideration of soot characteristics, spray structure and combustion characteristics, the soot formation process of the methanol diesel engine was clarified.

Plugin hybrid electric vehicles (PHEVs) have several attractive features in terms of reduction of greenhouse gas (GHG) emissions. Compared to conventional vehicles (CVs) that only have an internal combustion engine (ICE), PHEVs have better energy efficiency like regular hybrids (HEVs), allow for electrifying an appreciable portion of traveled miles, and have no range anxiety issues like battery-only electric vehicles (BEVs). However, in terms of criteria emissions (e.g., NOx, NMOG, HC), it is unclear if PHEVs are any better than HEVs or CVs. Unlike GHG emissions, criteria emissions are not continuously emitted in proportional quantities to fossil fuel consumption. Rather, the amount and type of criteria emissions is a rather complex function of many factors, including type of fuel, ICE temperature, speed and torque, catalyst temperature, as well as the ICE controls (e.g., fuel-to-air ratio, valve and ignition timing).

In the field of automobile disk wheels, demands for aluminum wheels have been increasing for the reason of ride comfort and better appearance. And over 90 percent of luxurious passenger cars are equipped with aluminum wheels. This trend is spurred also by the demand for higher fuel efficiency for the cause of environmental protection, which calls for weight reduction of automobiles. This paper reports our research on manufacturing light-weight, high-quality aluminum cast wheels; covering the entire process from basic design to casting, and placing emphasis on the following three points. 1) Determination of optimum wheel configuration through computer simulation 2) Selection of optimum material composition 3) Optimization of the thin plate casting conditions Combination of the above technologies developed for the purpose of weight reduction resulted in the weight reduction of approximately 20% over the conventional aluminum wheels.

The effects of multiple-injection on exhaust emissions and performance in a small HSDI (High Speed Direct Injection) Diesel engine were examined. The causes for the improvement were investigated using both in-cylinder observation and three-dimensional numerical analysis methods. It is possible to increase the maximum torque, which is limited by the exhaust smoke number, while decreasing the combustion noise under low speed and full load conditions by advancing the timing of the pilot injection. Dividing this early-timed pilot injection into two with a small fuel amount is effective for further decreasing the noise while suppressing the increase in HC emission and fuel consumption. This is realized by the reduced amount of adhered fuel to the cylinder wall. At light loads, the amount of pilot injection fuel must be reduced, and the injection must be timed just prior to the main injection in order to suppress a possible increase in smoke and HC.

The demand for thermal comfort in the passenger vehicle compartment is infinite. As a result, technologically sophisticated options and features continue to be upgraded both in the hardware and software sectors. The personalization of comfort became a priority and led to improvements in automatic room temperature control techniques. Furthermore, the demand is rising not only for thermal comfort but also for cabin air quality improvement. Also, contributions to improve mileage and fuel consumption are a new request at the present time. This paper introduces the latest thermal comfort technologies in temperature and airflow controls as well as air quality improvement features. In addition, this paper introduces fuel consumption reduction technology employed by the A/C configuration of the TOYOTA HYBRID SYSTEM.

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.