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Application of Models of Short Circuits and Blow-Outs of Spark Channels under High-Velocity Flow Conditions to Spark Ignition Simulation

DENSO Corp.-Akimitsu Sugiura
Toyota Central R&D Labs., Inc.-Ryo Masuda, Shogo Sayama, Takayuki Fuyuto, Makoto Nagaoka
Published 2018-09-10 by SAE International in United States
This report describes the implementation of the spark channel short circuit and blow-out submodels, which were described in the previous report, into a spark ignition model. The spark channel which is modeled by a particle series is elongated by moving individual spark particles along local gas flows. The equation of the spark channel resistance developed by Kim et al. is modified in order to describe the behavior of the current and the voltage in high flow velocity conditions and implemented into the electrical circuit model of the electrical inductive system of the spark plug. Input parameters of the circuit model are the following: initial discharge energy, inductance, internal resistance and capacitance of the spark plug, and the spark channel length obtained by the spark channel model. The instantaneous discharge current and the voltage are obtained as outputs of the circuit model. When two arbitrary spark particles of the spark channel get close, the short circuit occurs if the electric potential differences between the two locations exceed a certain threshold voltage, which is raised with increasing…
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Backward Flow of Hot Burned Gas Surrounding High-Pressure Diesel Spray Flame from Multi-hole Nozzle

SAE International Journal of Engines

DENSO Corp.-Makoto Mashida
Nippon Soken Inc.-Hayato Yamashita
  • Journal Article
  • 2015-01-1837
Published 2015-09-01 by SAE International in United States
The backward flow of the hot burned gas surrounding a diesel flame was found to be one of the factors dominating the set-off length (also called the lift-off length), that is, the distance from a nozzle exit into which a diffusion flame cannot intrude. In the combustion chamber of an actual diesel engine, the entrainment of the surrounding gas into a spray jet from a multi-hole nozzle is restricted by the walls and adjacent spray jets, which induces the backward flow of the surrounding gas. A new momentum theory to calculate the backward flow velocity was established by extending Wakuri's momentum theory. Shadowgraph imaging in an optical engine successfully visualized the backward flow of the hot burned gas.
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Quantification of Interface Thermal Resistance and Prediction of Thermal Conductivity by Observation of Stereoscopic Filler Dispersion in Polymer Composites

DENSO Corp.-Osamu Arao
Published 2015-04-14 by SAE International in United States
In electronic products, the recently increasing thermal radiation demands higher thermal conductivity of polymer composites. However, inaccurate observation of the filler dispersion within the polymer does not allow for accurate quantification of Interface Thermal Resistance and subsequently the prediction of thermal conductivity. Therefore, optimum filler design could not be achieved.Firstly in this report, accurate stereoscopic filler dispersion was observed by FIB-SEM. Secondly, quantification of Interface Thermal Resistance could be achieved by thermal conduction analysis using filler dispersion model. Thirdly, this Interface Thermal Resistance enabled the prediction of the thermal bulk conductivity. Lastly, the prediction made above could be validated by comparison of predicted value to measured value.This result may lead to optimum filler design and thereby to the development of higher thermal radiation materials.
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A Novel Distortion Cancelling Technique Enabling 50-Mbps High Speed Data Transmission for Bus Connected ECUs

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

DENSO Corp.-Hironobu Akita, Nobuaki Matsudaira, Chao Chen, Takasuke Ito, Shigeki Ohtsuka
  • Journal Article
  • 2015-01-0198
Published 2015-04-14 by SAE International in United States
With the evolution of automotive features, larger flash program size has been required even at the local electronic control units (ECUs). As the flash programming data rate increases, Ethernet is adopted as a global data port from the external source. However, it can not be applied to the bus type network topology between the domain control unit (DCU) and the local ECUs, because it uses a peer-to-peer type network topology. On the other hand, high speed CAN-FD has been studied recently for this bus topology, but its data rate is limited at the range of several mega bps due to the signal waveform distortion caused by the multiple reflections at the non-terminated stubs.This paper describes a novel distortion cancelling for the bus topology as the pre-emphasis technique, in which the digital signal processing (DSP) compensates the complicated signal distortion caused by the multiple reflections. Moreover, this complex signal processing block is located only at the DCU, not at the local ECUs. Therefore, the increase in cost can be suppressed effectively for the total system. The…
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Thin-Film Air Flow Sensors for Automotive using the MEMS Technologies

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

DENSO Corp.-Takamoto Furuichi, Takashige Nagao, Hisanori Yokura, Ryuichirou Abe, Shigemitsu Fukatsu
  • Journal Article
  • 2015-01-0233
Published 2015-04-14 by SAE International in United States
This paper presents two newly developed technologies of optimizing impurity diffusion concentration for silicon semiconductor material and controlling internal stress of the top SiN (Silicon Nitride) layer on a membrane of a silicon substrate to apply them to the manufacturing process of MEMS (Micro Electro Mechanical Systems) type air-flow sensor chips. Until today, in MEMS-type airflow sensors, poly-crystalline silicon (poly-Si) and platinum were widely used as a resistor material of key functional elements on a membrane of air-flow-rate measurement portion. The functional resistors on the membrane are required to monitor high temperatures of about 300 °C and to perform the self-heating operations at that temperature range because of the suppression of contaminant deposition by means of evaporation or incineration. However, the use of those resistor materials at such high-temperatures is very difficult because high-temperature use causes the problems of the sensing error expansion, the resistor material layer delamination etc. Therefore, we have developed a new MEMS-type air-flow sensor with high-temperature usable resistors which are formed in a single-crystal-semiconductor silicon of SOI (Single-crystal Si on insulator)…
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Study of Ignition System for Demand Voltage Reduction

DENSO Corp.-Yuya Abe, Akimitsu Sugiura, Kaori Doi, Masamichi Shibata
Toyota Motor Corp.-Nozomi Yokoo, Koichi Nakata
Published 2015-04-14 by SAE International in United States
Improving the engine efficiency to respond to climate change and energy security issues is strongly required. In order to improve the engine efficiency, lower fuel consumption, and enhance engine performance, OEMs have been developing high compression ratio engines and downsized turbocharged engines. However, higher compression ratio and turbocharging cause cylinder pressure to increase, which in turn increases the demand voltage for ignition.To reduce the demand voltage, a new ignition system is developed that uses a high voltage Zener diode to maintain a constant output voltage. Maintaining a constant voltage higher than the static breakdown voltage helps limit the amount of overshoot produced during the spark event. This allows discharge to occur at a lower demand voltage than with conventional spark ignition systems.The results show that the maximum reduction in demand voltage is 3.5 kV when the engine is operated at 2800 rpm and 2.6 MPa break mean effective pressure. However, as engine speed increases, the demand voltage reduction decreases. This paper shows the reduction effects at several engine speeds and explains why the demand voltage…
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An Investigation into the Effect of Fuel Injection System Improvements on the Injection and Combustion of DiMethyl Ether in a Diesel Cycle Engine

DENSO Corp.-Masaaki Kato, Takamasa Yokota
AVL LIST GmbH-Denis W. Gill, Herwig Ofner, Carsten Stoewe, Karl Wieser, Ernst Winklhofer
Published 2014-10-13 by SAE International in United States
For nearly twenty years, DiMethyl Ether has been known to be an outstanding fuel for combustion in diesel cycle engines. Not only does it have a high Cetane number, it burns absolutely soot free and produces lower NOx exhaust emissions than the equivalent diesel.However, the physical properties of DME such as its low viscosity, lubricity and bulk modulus have negative effects for the fuel injection system, which have both limited the achievable injection pressures to about 500 bar and DME's introduction into the market. To overcome some of these effects, a common rail fuel injection system was adapted to operate with DME and produce injection pressures of up to 1000 bar.To understand the effect of the high injection pressure, tests were carried out using 2D optically accessed nozzles. This allowed the impact of the high vapour pressure of DME on the onset of cavitation in the nozzle hole to be assessed and improve the flow characteristics. CFD simulation was also used to assist in the interpretation of the 2D test results.Tests were then run on…
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Study of Low-Speed Pre-Ignition in Boosted Spark Ignition Engine

SAE International Journal of Engines

DENSO Corp.-Yutaka Hayakawa
Nippon Soken, Inc.-Yoshihiro Izumi
  • Journal Article
  • 2014-01-1218
Published 2014-04-01 by SAE International in United States
This paper analyzes low-speed pre-ignition (LSPI), a sudden pre-ignition phenomenon that occurs in downsized boosted gasoline engines in low engine speed high-load operation regions.This research visualized the in-cylinder state before the start of LSPI combustion and observed the behavior of particles, which are thought to be the ignition source. The research also analyzed pre-ignition by injecting deposit flakes and other combustible particulate substances into the combustion chamber. The analysis found that these particles require at least two combustion cycles to reach a glowing state that forms an ignition source. As a result, deposits peeling from combustion chamber walls were identified as a new mechanism causing pre-ignition.Additionally, results also suggested that the well-known phenomenon in which the LSPI frequency rises in accordance with greater oil dilution may also be explained by an increase in deposit generation.
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New MEMS Process Technology for Pressure Sensors Integrated with CMOS Circuits

DENSO Corp.-Shinya Asai, Ryuichirou Abe, Yoshiko Isobe, Noriyuki Iwamori
Published 2014-04-01 by SAE International in United States
This paper describes the newly developed processes of low temperature wafer bonding using plasma activation and deep dry silicon etching technologies. Both processes are a new type of “MEMS” (Micro Electro Mechanical System) process technology suitable for automotive pressure sensors. The conventional pressure sensor was a unified unit consisting of a silicon sensor chip and a glass stage. The diced unified unit was cut from a bonded disk of a processed silicon wafer and a glass stage substrate, and the silicon sensor chip incorporated four piezo-resistors, a diaphragm and bipolar-circuit. However, the pressure sensor had difficulty in accurately measuring pressure in the high temperature range because of the thermal strain caused by the thermal expansion coefficient difference between the silicon sensor chip and the glass stage. By changing the stage substrate material from glass to silicon, this has eliminated the difference of the thermal expansion coefficient between the silicon sensor chip and the stage, and resulted in making it possible to accurately measure pressure in a high temperature environment such as a vehicle's engine room.…
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Reduction of the BPF Noise Radiated from an Engine Cooling Fan

DENSO Corp.-Kenji Yoshida, Junichi Semura
Tokyo City Univ.-Itsuhei Kohri
Published 2014-04-01 by SAE International in United States
This study investigates the reduction of the Blade Passing Frequency (BPF) noise radiated from an automotive engine cooling fans, especially in case of the fan with an eccentric shroud.In recent years, with the increase of HV and EV, noise reduction demand been increased. Therefore it is necessary to reduce engine cooling fan noise.In addition, as a vehicle trend, engine rooms have diminished due to expansion of passenger rooms. As a result, since the space for engine cooling fans need to be small. In this situation, shroud shapes have become complicated and non-axial symmetric (eccentric).Generally, the noise of fan with an eccentric shroud becomes worse especially for BPF noise. So it is necessary to reduce the fan BPF noise.The purposes of this paper is to find sound sources of the BPF noise by measuring sound intensity and to analyze the flow structure around the blade by Computational Fluid Dynamics (CFD).From the present results, suggest a design concept of the shroud shape to reduce the fan BPF noise is suggested.
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