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Technical Paper
2014-10-13
Kosuke Fujimoto, Minoru Yamashita, Satoshi Hirano, Katsuyoshi Kato, Izumi Watanabe, Koki Ito
Automotive companies have been working on technology development for reducing CO2 emission during driving cycle to be more environmentally conscious and to meet strict CO2 emission standard. Gasoline engine downsizing with turbocharger and direct-injection system is one of the effective approaches to improve fuel efficiency of vehicles without sacrificing power performance. The benefit comes from lower mechanical friction due to down-sizing of the engine displacement and down-speeding of the engine by using higher transmission gear ratios which is allowed by the higher engine torque at low engine speed. However abnormal combustion referred to as Low-Speed Pre-ignition (LSPI) often occurs in low-speed and high-torque conditions. Therefore the engine torque improvement at low engine speed must be limited to avoid the LSPI event, since it increase combustion chamber pressure significantly and may damage engine hardware. According to recent technical reports, auto-ignition of engine oil droplet in combustion chamber is believed to be a major contributing factor of LSPI and engine oil formulations have a significant effect on LSPI frequency.
Technical Paper
2013-10-14
Ken-ichi Kohashi, Yuichiro Kimura, Motoichi Murakami, Yann Drouvin
The purpose of this study is to analyze the piston skirt friction reduction effect of a diamond-like carbon (DLC)-coated wrist pin. The floating liner method and elasto-hydrodynamic lubrication (EHL) simulation were used to analyze piston skirt friction. The experimental results showed that a DLC-coated wrist pin reduced cylinder liner friction, and that this reduction was particularly large at low engine speeds and large pin offset conditions. Friction was particularly reduced at around the top and bottom dead center positions (TDC and BDC). EHL simulation confirmed that a DLC-coated wrist pin affects the piston motion and reduces the contact pressure between the piston skirt and cylinder liner.
Technical Paper
2013-04-08
Takahito Nozawa, Sumikazu Shamoto, Tomoya Katanoda
Recently, automakers have launched various types of electric vehicles (EVs) to help reduce global CO₂ emissions and reduce dependency on fossil fuel energy. Because the lithium-ion batteries that are currently under development are restricted by energy density, the physical size and mass of the battery must be significantly increased to extend the cruising range of the EV. Furthermore, dedicated charging infrastructure is required to charge the battery in a short time. At SAE in 2012, Toyota Motor Corporation proposed a concept that described the EV as suitable mainly for short-distance transportation now and in the near future. Later in the same year, Toyota launched a new EV that embodies this concept in the American and Japanese markets. This new EV is light-weight and has a compact body size, and its battery capacity is designed to sufficiently cover distances traveled in daily life. Charging is assumed to take place mainly at home. To maximize the performance of the lithium-ion battery, the condition of each battery cell is directly monitored on a constant basis, and each cell is reliably protected.
Technical Paper
2013-04-08
Yoshinori Otsuki, Tatsuki Kumagai, Hiroshi Nakamura, Katsushi Taguchi, Nobuhisa Mori
Conventional constant volume sampling (CVS) is well known as a precision emissions measurement method, even though the concentrations of THC, NOX, CO and CH₄ emitted from vehicles are getting lower by improvement of emissions control devices. Recently, fuel economy requirements have increased in many regions. Hybrid electric vehicle (HEV), or plug-in hybrid electric vehicle (PHEV), is one of the solutions for fuel economy improvement. HEVs and PHEVs have an all-electric range in which the internal combustion engines (ICEs) are completely shut down. This operation results in a high dilution factor (DF) and low concentrations of gaseous components, including CO₂, in the CVS system. Such dilution conditions directly cause an increase of numerical error for DF and an analysis error for gaseous components. Furthermore, a small amount of air flow across exhaust catalysts, drawn by slightly negative tailpipe pressure generated by the CVS during ICE shutdown may influence emission results. A new emissions measurement method which provides intermittent sampling synchronized with ICE operating modes has been introduced for HEVs and PHEVs.
Technical Paper
2013-04-08
Shin Noumura, Shogo Matsumoto, Toshio Tanahashi
The purpose of this research is to develop an automatic shift control method that emulates an experienced driver's manual shift maneuver which enhances driving performance during sporty driving. Driver control maneuvers and vehicle behavior were observed throughout the process of braking, cornering, and accelerating out of a corner on a winding test track. Close correlations were found between driving maneuvers, longitudinal and lateral acceleration, and the selected engine speed. Based on the analysis, an index is proposed for estimating the intention of the driver to drive in a sporty manner. This index consists of the magnitude of acceleration in a friction circle and the maximum longitudinal acceleration restricted by the performance of the power train. An automatic transmission control based on the estimated driving intention was then developed to achieve the necessary and sufficient available force. This paper discussed the details of the experimental results and analytical studies.
Technical Paper
2013-04-08
Junji chisaki, Kazuya Yoshijima, Takashi Kikuchi, Shoichiro Morinaka, Kenichi Yamada, Masaaki Okamoto, Tsutomu Oda, Keisuke Manabe
Toyota Motor Corporation aims to develop vehicles that are both fun to drive and fuel efficient, using highly reliable, low cost, and fundamental technology. This approach focuses on the accumulation of incremental improvements to combustion characteristics and friction, making the best use of the maximum potential of the displacement of a new 2.0-liter fuel-efficient diesel engine. This new engine has been launched in several markets around the world for the Avensis, the Auris, the RAV4, and the Verso since November of 2011. This paper presents an outline of this new engine and its technology.
Technical Paper
2013-04-08
Yusuke Takasu, Satoshi Kaneko, Hiroyuki Tominaga, Yoshikazu Namura, Kazuhisa Inagaki, Matsuei Ueda, Toshihiro Tani
The aim of this research is to develop the diesel combustion simulation (UniDES: Universal Diesel Engine Simulator) that incorporates multiple-injection strategies and in-cylinder composition changes due to exhaust gas recirculation (EGR), and that is capable of high speed calculation. The model is based on a zero-dimensional (0D) cycle simulation, and represents a multiple-injection strategy using a multi-zone model and inhomogeneity using a probability density function (PDF) model. Therefore, the 0D cycle simulation also enables both high accuracy and high speed. This research considers application to actual development. To expand the applicability of the simulation, a model that accurately estimates nozzle sac pressure with various injection quantities and common rail pressures, a model that accounts for the effects of adjacent spray interaction, and a model that considers the NOx reduction phenomenon under high load conditions were added. In addition, engine, vehicle, and driver models using the commercial GT-Power code, and an electronic control unit (ECU) model were combined to predict transient phenomena.
Technical Paper
2013-04-08
Toshinari Sano, Mitsuaki Tomita, Masashi Inoue, Yasuhiro Takeuchi, Muneo Yorinaga
This report proposes a rheological model and a thermal analysis model for oil films, which transmit power through a variator, as a prediction method for the maximum traction coefficient, and then describes the application and verification of this method. The rheological model expresses the conditions inside the contact ellipse using a combination of viscosity and plasticity. The thermal analysis model for oil films was confirmed by comparison of previously obtained temperatures directly measured from the traction contact area of the four-roller experimental apparatus [1]. The measurement used a thin-film temperature sensor and the consistency between the calculated and measured values was verified in the estimation model by reflecting the precise thermal properties of the thin film. Most values were consistent with the calculated values for the middle plane local shear heating model inside the oil film. However, under some conditions, the values were closer to those calculated for homogeneous shear.
Technical Paper
2013-04-08
Masashi Inoue, Yasuhiro Takeuchi, Muneo Yorinaga, Toshinari Sano, Mitsuaki Tomita
The purpose of this paper is to construct the thermal analysis model by measuring and estimating the temperature at the traction contact area. For measurement of temperature, we have used a thin-film temperature sensor. For estimation of temperature, we have composed the thermal analysis model. The thin-film temperature sensor was formed on the contact surface using a spattering device. The sensor is constituted of three layers (sensor layer, insulation layer and intermediate layer). Dimensions of the sensor were sufficiently smaller than the traction contact area. The sensor featured high specific pressure capacity and high speed responsiveness. The thermal analysis model was mainly composed of three equations: Carslaw & Jaeger equation, Rashid & Seireg equation and heat transfer equation of shear heating in oil film. The heat transfer equation involved two models (local shear heating model at middle plane, homogeneous shear heating model). The accuracy of the thermal analysis model was verified by two methods.
Technical Paper
2013-04-08
Kunio Hattori, Shinya Toyoda, Daisuke Inoue, Yuya Shimozato
Toyota has developed a new belt-type continuously variable transmission (CVT) for 1.5-liter compact vehicles. To improve both driveability and fuel economy over previous CVTs, pressure management was adopted as the shift control method. The new shift control system was designed using a model-based control method which uses a two-degree-of-freedom system composed of feedback and feedforward controls. Smooth shifting in all the target shift speed regions was realized by combining a feedback loop that considers the output limit of the pulley thrust into the feedforward controller. Furthermore, shift response was improved while maintaining or even improving stability. This paper describes the details of this shift control system.
Technical Paper
2013-04-08
Jared Farnsworth, Koichi Ueda, Hideaki Mizuno, Michio Yoshida
The application of Model-Based Development (MBD) techniques for automotive control system and software development have become standard processes due to the potential for reduced development time and improved specification quality. In order to improve development productivity even further, it is imperative to introduce a systematic Verification and Validation (V&V) process to further minimize development time and human resources while ensuring control specification quality when developing large complex systems. Traditional methods for validating control specifications have been limited by control specification scale, structure and complexity as well as computational limitations restricting their application within a systematic model-based V&V process. In order to address these issues, Toyota developed Hierarchical Accumulative Validation (HAV) for systematically validating functionally structured executable control specifications. HAV can be implemented in a production vehicle development cycle to ensure specification quality while saving development time and reducing required staff.
Technical Paper
2013-04-08
Hisahiro Ito, Hironori Yohata, Junichi Kako, Yukio Kuroda
A novel plant modeling method called High Level Modeling (HLM) to design and develop control-oriented plant model is introduced. The HLM method is specifically designed to expose the design intention at physics level of a target physical system in a straightforward manner so that plant models can be efficiently understood and peer-reviewed from the physical standpoint. The method also enables construction of system equations from the design information based on simple formal rules which guarantees conservation laws. To show the effectiveness of the HLM approach through a concrete use case, it is applied to turbocharger radial compressor modeling, and analysis on the model equations is performed by deriving compressor speed lines and efficiency.
Technical Paper
2013-04-08
Hayato Nakada, Gareth Milton, Peter Martin, Akiyuki Iemura, Akira Ohata
This paper considers an application of reference governor (RG) to automotive diesel aftertreatment temperature control. Recently, regulations on vehicle emissions have become more stringent, and engine hardware and software are expected to be more complicated. It is getting more difficult to guarantee constraints in control systems as well as good control performance. Among model-based control methods that can directly treat constraints, this paper focuses on the RG, which has recently attracted a lot of attention as one method of model prediction-based control. In the RG, references in tracking control are modified based on future prediction so that the predicted outputs in a closed-loop system satisfy the constraints. This paper proposes an online RG algorithm, taking account of the real-time implementation on engine embedded controllers. In order to realize the online RG algorithm, the following three elements are needed: (i) a plant model to predict future behavior of the control system, (ii) an objective function that quantifies how suitable a modified reference candidate is, and (iii) an online optimization algorithm that computes the most suitable modified reference from a set of candidates.
Technical Paper
2012-09-17
Tomohiro Yokoyama, Toru Matsushima, Noriyoshi Matsui, Ryutaro Misumi
Brake squeal is a phenomenon of self-induced vibration of the brake components during braking. There are many kinds of brake squeal cases whose mechanisms require acting on a various number of potential root causes. Brake squeal phenomena can be generally separated into 2 main mode types related to the direction of disc vibration involved: in-plane mode and out-of-plane mode. For out-of-plane mode, a number of existing countermeasures can be potentially applied after characterization of the squeal occurrence condition by direct experiment or simulation analysis[1,2,3,4]. However, as there are many possible mechanisms and root causes for the in-plane modes[5,6,7,8,9,10,11,12,13], it is generally necessary to perform a detailed analysis of the vibration mechanism before implementing a countermeasure. In this case, this paper reports a particular of in-plane brake squeal case where traditional countermeasure proved ineffective, but which could be solved by changing the disc design based on the comprehensive understanding of the mechanism.
Technical Paper
2012-09-10
Satoshi Taniguchi, Masahiko Masubuchi, Koji Kitano, Kazuhisa Mogi
The Diesel Dual Fuel (DDF) vehicle is one of the technologies to convert diesel vehicles for natural gas usage. The purpose of this research was to study the possibility of a DDF vehicle to meet emission standards for diesel vehicles. This research was done for small passenger vehicles and commercial vehicles. The exhaust emissions compliance of such vehicles in a New European Driving Cycle (NEDC) mode which was composed of Urban Driving Cycles (UDC) and an Extra Urban Driving Cycle (EUDC) was evaluated. (see APPENDIXFigure A1) In this study, the passenger vehicle engine, compliant with the EURO4 standard, was converted to a DDF engine. Engine bench tests under steady state conditions showed similar result to previous papers. Total hydrocarbon (HC) emission was extremely high, compared to diesel engine. The NEDC mode emissions of the DDF vehicle were estimated based on these engine bench test results. The results indicate that the HC + nitrogen oxides (NOx) emission of the DDF is approximately six times higher than the EURO4 regulation and it doesn't meet the EURO4 standard due to the high HC emission.
Technical Paper
2012-09-10
Yuki Bisaiji, Kohei Yoshida, Mikio Inoue, Nobuyuki Takagi, Takao Fukuma
The details of Di-Air, a new NOx reduction system using continuous short pulse injections of hydrocarbons (HC) in front of a NOx storage and reduction (NSR) catalyst, have already been reported. This paper describes further studies into the deNOx mechanism, mainly from the standpoint of the contribution of HC and intermediates. In the process of a preliminary survey regarding HC oxidation behavior at the moment of injection, it was found that HC have unique advantages as a reductant. The addition of HC lead to the reduction or metallization of platinum group metals (PGM) while keeping the overall gas atmosphere in a lean state due to adsorbed HC. This causes local O₂ inhibition and generates reductive intermediate species such as R-NCO. Therefore, the specific benefits of HC were analyzed from the viewpoints of 1) the impact on the PGM state, 2) the characterization of intermediate species, and 3) Di-Air performance compared to other reductants. As a result, the operando dispersive X-ray adsorption fine structure (DXAFS) method was used to find that HC prolong the metallic state of Pt compared to CO and H₂ during a period of time lasting a number of seconds under a lean atmosphere.
Technical Paper
2012-09-10
Kazuo Takeuchi, Kosuke Fujimoto, Satoshi Hirano, Minoru Yamashita
Abnormal combustion referred to as Low Speed Pre-Ignition (LSPI) may restrict low speed torque improvements in turbocharged Direct Injection (DI) - Spark Ignition (SI) Engines. Recent investigations have reported that the auto-ignition of an engine oil droplet from the piston crevice in the combustion chamber may cause unexpected and random LSPI. This study shows that engine oil formulations have significant effects on LSPI. We found that the spontaneous ignition temperature of engine oil, as determined using High-Pressure Differential Scanning Calorimetry (HP-DSC) correlates with LSPI frequency in a prototype turbocharged DI-SI engine. Based on these findings, we believe that the oxidation reaction of the oil is very important factor to the LSPI. Our test data, using a prototype engine, shows both preventative and contributory effects of base oil and metal-based engine oil additives.
Technical Paper
2012-09-10
Kosuke Fujimoto, Minoru Yamashita, Toyoharu Kaneko, Satoshi Hirano, Yusuke Ito, Shuzo Nemoto, Ko Onodera
We report in this paper our newly developed technology applied to ILSAC GF-5 0W-20 engine oil that offers great fuel economy improvement over GF-4 counterpart, which is a key performance requirement of modern engine oil to reduce CO2 emissions from a vehicle. Our development strategy of the oil consisted of two elements: (1) further friction reduction under mixed and hydrodynamic lubrication conditions considering use of roller rocker arm type valve train system and (2) lowering viscosity at low temperature conditions to improve fuel economy under cold cycles. Use of roller rocker arm type valve train system has been spreading, because of its advantage of reducing mechanical friction. Unlike engine with conventional direct-acting type valve train system, lubrication condition of engine with the roller rocker arm type valve train system has higher contribution of mixed or hydrodynamic lubrication conditions rather than boundary lubrication condition. Therefore, engine oil for new vehicles, equipped with roller rocker arm type valve train system, should have better friction reduction performance under mixed or hydrodynamic lubrication conditions.
Technical Paper
2012-04-16
Kimitoshi Tsuji, Takashi Abe, Toshiji Kato, Yasunari Kido
In order to reduce CO₂, Electric Vehicles (EV) and Hybrid Vehicles (HV) are effective. Those types of vehicles have powertrains from conventional vehicles. Those new powertrains drastically improve their efficiency from conventional vehicles keeping the same or superior power performance. On the other hand, those vehicles have an issue for thermal energy shortage during warming up process. The thermal energy is very large, and seriously affects the fuel economy for HV and the mileage for EV. In this paper, we propose VHDL-AMS multi-domain simulation technique for the estimation of the vehicle performance at the concept planning stage. The VHDL-AMS is IEEE and IEC standardized language, which supports not only multi-domain (physics) but also encryption. The common modeling language and encryption standard is indispensable for full-vehicle simulation. By the VHDL-AMS modeling, the fuel economy, the effect of heat energy recovery from the exhaust gas, and the power performance are discussed for HV.
Technical Paper
2012-04-16
Takashi Uehara, Yasuhiro Takahashi, Ryoji Oki, Takahiko Hirasawa, Yusuke Kamijyo, Ikuo Ando, Ryuta Teraya, Makoto Nakamura
Reflecting on the world's trend on saving crude oil consumption and to create an economical fuel efficient vehicle for the increasing world population, a new THS-II HV powertrain has been developed for the compact vehicle class. The application of a THS type powertrain for the compact vehicle class was a first for the world and to achieve it, brand new hardware, and software needed to be developed. For the Internal Combustion Engine (ICE), state of the art technologies such as the use of the Atkinson cycle with Variable Valve Timing (VVT), cooled exhaust gas recirculation (EGR), an electric water pump, a compact exhaust manifold, a Low Friction chain, beltless system and exhaust heat recovery system were applied. For the electric motor, copper wire with a rectangular cross section and divided stator cores combined with a newly developed production process were applied for higher volumetric density. For the transaxle; parts location, bearing specifications, and the cooling systems were redesigned to be more compact.
Technical Paper
2012-04-16
Kensuke Kamichi, Masaya Yamamoto, Shunsuke Fushiki, Takehito Yoda, Saeko Kurachi, Koichi Kojima
In recent years, many various energy sources have been investigated as replacements for traditional automotive fossil fuels to help reduce CO₂ emissions, respond to instabilities in the supply of fossil fuels, and reduce emissions of air pollutants in urban areas. Toyota Motor Corporation considers the plug-in hybrid vehicle, which can use electricity efficiently, to be the most practical current solution to these issues. For this reason, Toyota began sales of the Prius plug-in hybrid in early 2012 in both the U.S. and Japan. This is the first plug-in hybrid vehicle to be mass-produced by Toyota Motor Corporation. Prior to this, in December 2009, Toyota sold 650 plug-in hybrid vehicles through lease programs for verification testing in the U.S., Europe, and Japan. The system of the recently launched mass-produced vehicle underwent major improvements in response to the results of this verification testing. As a result, EV range was increased with a smaller battery. This development also succeeded in drastically reducing the weight of the system.
Technical Paper
2012-04-16
Tomoyuki Kaga, Masakazu Adachi, Ichiro Hosotani, Masaaki Konishi
Automotive control systems such as powertrain control interact with the open physical environment, and from this nature, expensive prototyping is indispensable to capture a deep understanding of the system requirements and to develop the corresponding control software. Model-based development (MBD) has been promoted to improve productivity by virtual prototyping. Even with MBD, systematic validation of the software specification remains as a major challenge and it still depends heavily on individual engineers' skill and knowledge. Though the introduction of graphical software modeling improved the situation, it requires much time to identify the primal functions, so-called “design interests”, from a large complex model where irrelevant components are mixed with, and to validate it properly. In addition, since software models have to coexist with legacy assets during the transition to MBD, the difficulty mentioned above should be overcome in terms of not only models, but also legacy C codes.
Technical Paper
2012-04-16
Julien Bouilly, Ali Mohammadi, Yutaka Iida, Hiromichi Hashimoto, Savas Geivanidis, Zissis Samaras
The effects of biodiesel oxidation stability on diesel fuel injection equipment (FIE) behavior were investigated using newly developed test rig and methodology. On the test rig, biodiesel blend fuels were circulated through a fuel tank and a common rail injection system. Fuel injected from typical diesel injectors was returned into the fuel tank to enhance the speed of fuel degradation. The results showed that injector deposits could be reproduced on a test rig. It was observed that injector body temperature increase accelerates the degradation of fuel and therefore gives earlier FIE failure. Fuel renewal could partially restore the injection quantity after complete failure at low injection pressure, thus showing a potential cleaning effect on injector deposits when refueling a car. Fuel quality was monitored during the rig test to investigate the degradation trends and it was seen that there are two major steps during fuel deterioration: an oxidation followed by an acidification together with increasing water content inside the fuel.
Technical Paper
2012-04-16
Yoshihisa Tsukamoto, Hiromasa Nishioka, Daichi Imai, Yuichi Sobue, Nobuyuki Takagi, Toshiyuki Tanaka, Tsuyoshi Hamaguchi
In this study, instead of investigating NOx storage reaction improvements, the NOx adsorption phenomenon was focused on and analyzed to improve NOx trapping performance at lower temperatures. As a NOx adsorbing material, "Ag" was expected to enhance NOx adsorption and reduce the sulfur regeneration temperature due to the abundance of adsorbed oxygen and moderate basicity. However, when using this material in an actual system, we had to reduce the sulfur regeneration temperature, increase NOx adsorption capacity and improve NOx desorption further. Addition of TiO₂, working as an acidic material, was found to decrease sulfur regeneration temperature. Additionally, it increased the NOx adsorption capacity through improved Ag dispersion which plays an important role in NOx adsorbing. Consequently, a greater NOx trapping performance than NSR catalyst was achieved at lower temperatures. In addition, we improved the NOx desorption property during diesel-rich combustion with a help of adding a minute amount of PGM, and improved the NOx reduction activity of Rhodium by improving the TWC.
Technical Paper
2012-04-16
Takeshi Uriu, Tsuyoshi Yasuki, Satoshi Fukushima, Masaaki Kuwahara
This paper describes the development of dummy FE models to be used for side impact simulations. The precise geometries of the ES-2re dummy and the SID-IIs dummy were measured at a pitch of 1.0 mm using X-ray CT scan. The material properties and the mechanical responses of the components were measured in static and dynamic tests and were used for the model validation. The models were further validated to US-NCAP side impact requirements. Good correlation was seen for both response time history, and to peak deformation values. It is shown that modeling the precise dummy internal structure in addition to the external geometry and applying accurate material properties enabled simulation of deformation kinematics and load transfer inside the dummies. As a result, it was possible to accurately simulate the injury value time histories in an actual test, and understand the mechanisms causing changes to the loading.
Technical Paper
2012-04-16
Mohd Radzi Abu Mansor, Shinji Nakao, Katsutaka Nakagami, Masahiro Shioji, Akira Kato
The ignition delay and combustion characteristics of hydrogen jets in an argon-oxygen atmosphere were investigated to provide fundamental data for operating an argon-circulated hydrogen internal combustion engine. Experiments were conducted in a constant-volume combustion vessel to study the effects of ambient temperature, ambient pressure, oxygen concentration and injection pressure on a pre-burning system. The hydrogen-jet penetration and flame were also investigated based on high-speed shadowgraph images. The experimental results indicated that the ignition delay (τ) increases as the ambient temperature (Ti) decreases, similar to the results obtained in an air atmosphere. The heat-release rate results also exhibited similar trends. In addition, other fundamental characteristics were investigated by modifying the oxygen concentration (rO2), ambient pressure (pi) and injection pressure (pj) conditions, which might help in controlling the operation in an argon-circulated hydrogen engine.
Technical Paper
2012-04-16
Tomoaki Furukawa, Ryuji Ibaraki, Hiroaki Kimura, Koichi Kondo, Masato Watanabe, Tatsuhiko Mizutani, Hiroyuki Hattori, Akira Takasaki
Recently, due to mounting concerns regarding the environment and energy conservation, demand for compact and hybrid vehicles with good fuel economy has been increasing. Toyota Motor Corporation has developed its first hybrid transaxle for installation in sub-compact class vehicles. This new hybrid transaxle is both smaller and lighter than the P410 hybrid transaxle for compact class vehicles, including the 2009 Prius. This was accomplished by creating new designs of the gear train, motor, and motor cooling system, and by adopting advanced technology. This paper describes the major features and performance of this transaxle in detail.
Technical Paper
2012-04-16
Jun Tajima, Norihiko Sakamoto, Tsutomu Mochida, Shin Tanaka, Hiroshi Yasuda
This paper proposes a novel method of verifying comprehensive driver model used for the evaluation of driving safety systems, which is achieved by coupling the traffic simulation and the driving simulator (DS). The method consists of three-step procedure. In the first step, an actual driver operates a DS vehicle in the traffic flow controlled by the traffic simulation. Then in the next step, the actual driver is replaced by a driver model and the surrounding vehicle maneuvers are replayed using the recorded data from the first step. Then, the maneuver by the driver model is compared directly with the actual driver's maneuver along the simulation time steps. For example, while turning right (in front of the oncoming traffic), the proposed verification method was applied to our driver-agent model of traffic simulation system ASSTREET (The Advanced Safety System & Traffic REaltime Evaluation Tool) to demonstrate that the proposed method provides a straightforward way of verifying the driver-agent model capability to reproduce the driving behavior including the subtle driving behaviors, such as safety confirmation, that can have significant impact on driving safety.
Technical Paper
2012-04-16
Yoshiaki Naganuma, Kota Manabe, Hiroyuki Imanishi, Yasuhiro Nonobe
Cold weather operation has been a major issue for fuel cell hybrid vehicles (FCHV). To counteract the effects of low temperatures on FCHV operation, an approach for rapid warm-up operation based on concentration overvoltage increase and conversion efficiency decrease by limiting oxygen or hydrogen supply was adopted. In order to suppress increases in exhaust hydrogen concentration due to pumping hydrogen during rapid warm-up, dilution control using bypass air and reduction of concentration overvoltage by a minimum voltage guard were implemented. These approaches effectively control waste heat generation and suppress exhaust hydrogen concentrations during cold start and warm-up. These developments were incorporated into the 2008 Toyota FCHV-adv and it was confirmed that the rapid warm-up operation strategy allowed the FCHV-adv to be successfully and repeatedly started at -30°C.
Technical Paper
2012-04-16
Shigetaka Hamada, Masaaki Kondo, Masahiro Shiozawa, Sogo Goto
For over a decade and a half, Toyota Motor Corporation has been developing fuel cell vehicles (FCVs) and is continuing various approaches to enable mass production. This study used new methods to quantitatively observe some of the mass transfer phenomena in the reaction field, such as oxygen transport, water drainage, and electronic conductivity. The obtained results are applicable to the design requirements of ideal reaction fields, and have the potential to assist to reduce the size of the fuel cell.
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