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Technical Paper

A target cascading method using model based simulation in early stage of vehicle development

2019-04-02
2019-01-0836
Vehicle specifications which satisfy various constraint conditions of target performance indices are required in the early stage of vehicle development. For this decision making, model based simulation plays important role to provide candidates of feasible specifications and can be used to find optimal specifications by applying optimization method. In order to enhance the efficiency of later development processes, those optimal specifications obtained from the optimization problem are required to be not only feasible but also flexible. To guarantee these requirements, it is important for decision maker to understand feasible region space and its mechanism where satisfies every constraint based on model based simulations. The purpose of this study is not to find best solution in design space but to understand feasible design space and its mechanism.
Technical Paper

A Study of Triple Skyhook Control for Semi-Active Suspension System

2019-04-02
2019-01-0168
It is said that a vertical vibration from 4 to 8 Hz (the mid-frequency range) particularly affects ride comfort. In order to suppress the mid-frequency range vibration, a number of control methods using a semi-active suspension system have been proposed. Skyhook damper control (SH) is a well-known strategy to suppress the vibration around the sprung mass resonance frequency about 1-2 Hz (the low-frequency range). However, the mid-frequency range vibration can’t be suppressed by SH. Therefore, dampers of the semi-active suspensions adopting SH are usually set soft to balance the low- and mid-frequency vibration. However, the soft dampers increase unsprung vibration opposite ride comfort. H-infinity and gain-scheduled approaches also have been proposed to achieve these multiple objectives. However, those controls have many tuning parameters and require information of unsprung vibration from sensors or accurate estimations.
Technical Paper

Development of Strength Distributed Hot Stamp Parts

2019-04-02
2019-01-0522
Structural parts, such as the center pillar, are a multiple structure, consisted by layers of the high-strength panels and the high-toughness panels, to control the deformation mode during a crash. If we are able to make this multi-layered structure into one panel, which has different hardness within it, we will be able to make a lightweight panel. In this study, we have developed the method to fabricate a ‘lightweight center pillar’ with the following processes. First, the whole surface of the panel is hardened by quenching in the hot stamp process. Next, certain areas of the panel are softened by the partial tempering. We have found that the temperature zone for softening is between A1 and A3 transformation temperature, and it is easy to perform a rapid and accurate tempering by utilizing the property of Induction Heating around the Curie temperature between A1 and A3 transformation temperature.
Technical Paper

Fatigue Life Prediction Method for Self Piercing Rivets Considering Crack Propagation

2019-04-02
2019-01-0531
This paper describes the numerical prediction method for fatigue strength of Self Piercing Rivets (SPRs) using fracture mechanics. Recently, high strength steels and non-ferrous metals are adopted to the light weight automotive body. Many kinds of joining are proposed for the multi material bodies. It is important to predict fatigue lives of these joints using the numerical simulation. However, the fatigue strength of joints is related to sheet thickness, base materials, and loading conditions. Therefore, a large number of coupon tests are necessary to determine the S-N curve for the fatigue life prediction of joints in the automotive body. To reduce the amount of coupon tests, the numerical simulation will be efficient for obtaining the S-N curve of joints instead of coupon tests. The fatigue fracture process consists of two stages, the small crack initiation and the crack growth. There are many studies about the crack growth estimation method using stress intensity factor.
Technical Paper

Development of TLP-AI Technology to realize high temperature operation of power module

2019-04-02
2019-01-0607
SiC power devices are promising components for the power module assembled in the automobile power control unit due to their low-power loss operation. Also they have high thermostable characteristics which are expected to tolerate high temperature operation, widening the range that the conventional Si device has limited. While, the packaging technology is also needed to improve the thermo-stability to derive the full potential of SiC power device, especially the device bonding which is directly related to the device thermally and physically. TLP bonding is one of the promising technologies for the high temperature operation because its bonding layer has high melting point. But there is a problem that characteristic of TLP bonding layer causes the damage to the power device.
Technical Paper

Research of Knocking Deterioration due to Accumulated Carbon Deposits on Piston Surfaces

2019-04-02
2019-01-1141
In recent years, fuel economy regulation is expanding to reduce CO2 emission and energy saving in world wide. To achieve the regulation, automaker efforts to develop electrification technology and improve engine thermal efficiency with high compression ratio. On the other hand, variety of fuels such as a reformed gasoline and bio fuel share is growing rapidly to utilize of fossil fuel by legal arrangements. With the spread of reformed gasoline, there are some risk of increased carbon deposit and accumulated on piston surface, due to heavy aromatic and olefin in the fuel. In combustion point of view, knocking should be deteriorated by synergy effect both accumulated carbon deposit and said high compression ratio. Furthermore, knocking deterioration do not occur in regularly, especially they occur in low-middle engine load. However, this mechanism is not clear.
Technical Paper

Using Chemical Kinetics to Understand Effects of Fuel Type and Compression Ratio on Knock-Mitigation Effectiveness of Various EGR Constituents

2019-04-02
2019-01-1140
Exhaust gas recirculation (EGR) can be used to mitigate knock in SI engines. However, experiments have shown that the effectiveness of various EGR constituents to suppress knock varies with fuel type and compression ratio (CR). To understand some of the underlying mechanisms by which fuel composition, octane sensitivity (S), and CR affect the knock-mitigation effectiveness of EGR constituents, the current paper presents results from a chemical-kinetics modeling study. The numerical study was conducted with CHEMKIN, imposing experimentally acquired pressure traces on a closed reactor model. Simulated conditions include combinations of three RON-98 (Research Octane Number) fuels with two octane sensitivities and distinctive compositions, three EGR diluents, and two CRs. The experimental results point to the important role of thermal stratification in the end-gas to smooth peak heat-release rate (HRR) and prevent acoustic noise.
Technical Paper

Effect of High RON Fuels on Engine Thermal Efficiency and Greenhouse Gas Emissions

2019-04-02
2019-01-0629
Increasing fuel octane is a well-known enabler for increasing spark-ignited engine efficiency. This research explores the impact of such a strategy on ‘well-to-wheel’ greenhouse gas emissions by considering 1) increases in emissions from producing higher octane fuels in the refinery, and 2) reductions in vehicle emissions through use of fuel-efficient engines optimized for such higher octane fuels. It also examines the impact of increases in fuel cost when refineries shift fuel production to higher octane. Three refinery configurations with different capacities to produce higher octane fuels were studied by simulating operations at three levels of high-octane gasoline production, as a function of the octane value for the high-octane grade. Two spark-ignited engine designs were considered, with different potential to take advantage of higher octane fuel to increase efficiency.
Technical Paper

Thermal Management of a Hybrid Vehicle Using a Heat Pump

2019-04-02
2019-01-0502
This paper presents the thermal management of a hybrid vehicle (HV) by using a heat pump system in cold weather. The advantage of an HV is a high efficiency of the vehicle system since an electric motor and an engine are coupled and optimally controlled. However, in the conventional HV, we see the fuel economy degradation in cold weather because delivering heat to the passenger cabin by using an engine results in a low efficiency of the vehicle system. To improve the fuel economy degradation, in this study, a heat pump is used and combined with an engine for the thermal management. The heat pump with an electrically driven compressor pumps heat from ambient into a water-cooled condenser. The heat which is generated by the engine and the heat pump is delivered to the engine and the passenger cabin because the engine needs to warm up quickly to reduce the emission and the cabin needs heat for thermal comfort.
Technical Paper

Kinetic Modeling of Ammonia-SCR and Experimental Studies over Monolithic Cu-ZSM-5 Catalyst

2019-01-15
2019-01-0024
Ammonia-selective catalytic reduction (SCR) systems have been introduced commercially in diesel vehicles, however catalyst systems with higher conversion efficiency and better control characteristics are required to know the actual emissions during operation and the emissions in random test cycles. Computational fluid dynamics (CFD) is an effective approach when applied to SCR catalyst development, and many models have been proposed, but these models need experimental verification and are limited in the situations they apply to. Further, taking account of redox cycle is important to have better accuracy in transient operation, however there are few models considering the cycle. Model development considering the redox reactions in a zeolite catalyst, Cu-ZSM-5, is the object of the research here, and the effects of exhaust gas composition on the SCR reaction and NH3 oxidation at high temperatures are investigated.
Technical Paper

A Statistical Approach to Improve the Accuracy of the DPF Simulation Model under Transient Conditions

2019-01-15
2019-01-0027
Cars with diesel engines are commonly equipped with a Diesel Particulate Filter (DPF) to reduce their emissions of particulate matter (PM). Because the pressure drop within the DPF reduces engine performance, it must be predicted with accuracy. The purpose of this study was to improve the accuracy of a DPF simulation model under transient conditions by parameter optimization. The DPF model under consideration consists of an inlet channel, a cake layer, wall layer, and an outlet channel. The pressure drop is influenced by the location, mass, and density of the deposited soot. Therefore, the model includes the following sub-models: Sub-model 1: Calculates the soot density deposited in the wall layer Sub-model 2: Computes the filtration efficiency and mass of the wall and cake layer Sub-model 3: Calculates the soot density deposited in the cake layer Because the sub-models include some empirical formulae, the first step in refining the model was to optimize their fitting parameters.
Technical Paper

A Numerical Study on Correlation of Chemiluminescent Species and Heat Release Distributions Using Large Eddy Simulation

2018-10-30
2018-32-0066
A mixed timescale subgrid model of a large eddy simulation was used to simulate the turbulence regime in diesel engine combustion. The combustion model used the direct integration approach with a diesel oil surrogate mechanism (developed at Chalmers University of Technology and consisting of 70 species and 309 reactions). Additional reactions for the generation and consumption of OH*, CO2*, and CH* species were added from recent kinetic studies. Collisional quenching and spontaneous emission resulted in de-excitation of the excited state radical. A phenomenological soot formation model (developed at Waseda University) was combined with the LES code. The following important steps were considered in the soot model: particle inception where naphthalene grows irreversibly to form soot, surface growth with the addition of C2H2, surface oxidation (induced by OH radicals and O2 attack), and particle coagulation.
Technical Paper

Experimental Study of Spark-Assisted Auto-Ignition Gasoline Engine with Octagonal Colliding Pulsed Supermulti-Jets and Asymmetric Double Piston Unit

2018-10-30
2018-32-0004
Much effort has been devoted to studies on auto-ignition engines of gasoline including homogeneous-charge combustion ignition engines over 30 years, which will lead to lower exhaust energy loss due to high-compression ratio and less dissipation loss due to throttle-less device. However, the big problem underlying gasoline auto-ignition is knocking phenomenon leading to strong noise and vibration. In order to overcome this problem, we propose the principle of colliding pulsed supermulti-jets. In a prototype engine developed by us, octagonal pulsed supermulti-jets collide and compress the air around the center point of combustion chamber, which leads to a hot spot area far from chamber walls. After generating the hot spot area, the mechanical compression of an asymmetric double piston unit is added in four-stroke operation, which brings auto-ignition of gasoline.
Technical Paper

Effects of Soot Deposition on NOx Purification Reaction and Mass Transfer in a SCR/DPF Catalyst

2018-09-10
2018-01-1707
Experimental studies were carried out to investigate the effect of soot deposition on NOx purification phenomena in an ammonia selective catalytic reduction coated diesel particulate filter (SCR/DPF) catalyst. To study soot deposition effects on the chemical reactions and mass transfer, two types of testing device were used. A synthetic gas bench enabling tests to be conducted with temperature and flow rate ranges relevant to real driving conditions was used to investigate the soot influence on reduction of NOx to N2 (DeNOx). A micro-reactor that removed the effect of soot deposition on mass transfer in the catalyst layer was used to analyze chemical reactions on a soot surface and their interaction with the SCR catalyst. A filter test brick of a Cu-zeolite SCR/DPF catalyst and a powder catalyst were used for the synthetic gas bench and micro-reactor tests, respectively. Engine soot was sampled in all the tests.
Technical Paper

The Effect of Gasoline Metallic Additives on Low Speed Pre-Ignition

2018-04-03
2018-01-0936
Methylcyclopentadienyl manganese tricarbonyl (MMT) is used as an octane-enhancing metallic additive for unleaded gasoline which can prevent engine knock by proactive reaction with the hydrocarbon free radicals before starting the auto-ignition of hydrocarbons. However it has been pointed out that MMT causes automotive catalysts clogging and spark plug severely fouling. Therefore, many countries have fuel standards that prohibit or limit the usage of MMT. Nevertheless, some countries still use MMT as there are no restrictions imposed by fuel standards. As mentioned in several papers, metallic additives of engine oil such as calcium cause an abnormal combustion phenomenon called low-speed pre-ignition (LSPI) in turbocharged spark ignition engines. In contrast, the effect of metallic additives of gasoline such as MMT on LSPI has not been studied.
Technical Paper

Development of Three-Way Catalysts Enhanced NOx Purifying Activity

2018-04-03
2018-01-0942
Growing concerns about the depletion of raw materials as vehicle ownership continues to increase is prompting automakers to look for ways of decreasing the use of platinum-group metals (PGMs) in the exhaust systems. This research has developed a new catalyst with strong robustness against fluctuations in the exhaust gas and excellent nitrogen oxide (NOx) conversion performance. One of the key technologies is a new OSC material that has low surface area (SA) and high OSC performance. We enhanced the pyrochlore- ceria/zirconia (CZ) which has a very small SA. In order to enhance the heat resistance and promote the OSC reaction, we selected and optimized the additive element. This material showed high OSC performance especially in the temperature range of 400 degrees or less. Another key technology is washcoat structure that has high gas diffusivity by making connected pore in the washcoat (New pore forming technology).
Technical Paper

Development of CFD Inverse Analysis Technology Targeting Heat or Concentration Performance Using the Adjoint Method and Its Application to Actual Components

2018-04-03
2018-01-1033
To resolve two major problems of conventional CFD-based shape optimization technology: (1) dependence of the outcome on the selection of design parameters, and (2) high computational costs, two types of innovative inverse analysis technologies based on a mathematical theory called the Adjoint Method were developed in previous studies for maximizing an arbitrary hydrodynamic performance aspect as the cost function: surface geometry deformation sensitivity analysis to identify the locations to be modified, and topology optimization to generate an optimal shape. Furthermore, these technologies were extended to transient flows by the application of the transient Adjoint Method theory. However, there are many cases around flow path shapes in vehicles where performance with respect to heat or concentration, such as the total amount of heat transfer or the flow rate of a specific gas component, is very important.
Technical Paper

Development of New Continuously Variable Transmission for 2.0-Liter Class Vehicles

2018-04-03
2018-01-1062
Toyota has developed a new continuously variable transmission (CVT) called "Direct Shift-CVT" which is for 2.0-liter class vehicles. This CVT provided not only power transmission by a metal belt held with a conventional pulley but also additional gear mechanism. This CVT is developed to improve fuel efficiency, acceleration characteristic, and quietness. At this CVT, the startup low gear ratio is achieved by gear mechanism and the power is switched by clutches. Since the belt-pulley portion can be realized to be wide range by using only high gear ratio range, the input load into belt-pulley portion is reduced and unprecedented compact and high efficient belt-pulley portion is established. Consequently, the high efficiency in all fields from startup acceleration to high speed driving is achieved to improve fuel efficiency.
Technical Paper

Update of the WorldSID 50th Male Pelvic Injury Criterion and Risk Curve

2018-04-03
2018-01-0539
Petit et al. 2015 and Lebarbé et al. 2016 reported on two studies where the injury mechanism and threshold of the sacroiliac joint were investigated in two slightly oblique crash test conditions from 18 Post Mortem Human Subjects (PMHS) tests. They concluded that the sacroiliac joint fractures were associated with pubic rami fractures. These latter being reported to occur first in the time history. Therefore it was recommended not to define a criterion specific for the sacroiliac joint. In 2012, injury risk curves were published for the WorldSID dummy by Petitjean et al. For the pelvis, dummy and PMHS paired tests from six configurations were used (n = 55). All of these configurations were pure lateral impacts. In addition, the sacroiliac joint and femur neck loads were not recorded, and the dummy used was the first production version (WorldSID revision 1). Since that time, the WorldSID was updated several times, including changes in the pelvis area.
Technical Paper

New 2.0L I4 Gasoline Direct Injection Engine with Toyota New Global Architecture Concept

2018-04-03
2018-01-0370
Toyota Motor Corporation has developed a new 2.0L Inline 4- Cylinder (I4) Gasoline Direct Injection Engine, the second Naturally Aspirated (NA) engine of the Toyota New Global Architecture (TNGA) engine series, to meet our customers’ expectations for drivability, performance, and fuel economy. The high speed combustion technologies adopted previously in our 2.5 L NA conventional and Hybrid Vehicle (HV) engines for the 2018 Toyota Camry are necessary for high engine power and thermal efficiency. To adopt our high speed combustion technology on engines with different displacements, the turbulence intensity has been defined as the target index of combustion speed. The basic engine structure has been revised by using Computational Fluid Dynamics (CFD) analysis to achieve the combustion target.
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