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High Resolution LiDAR Based on Single Chip SPAD Array

DENSO Corporation-Takehiro Hata, Noriyuki Ozaki, Yoshihiro Murakami, Kenta Azuma, Shinji Kashiwada, Kenichi Yanai
Published 2019-04-02 by SAE International in United States
It is important that Advanced Driver Assistance Systems (ADAS) and Automated Driving Systems (AD) detect on-road objects, road vehicles and pedestrians. The typical detection devices mounted on ADAS and AD include a camera, a millimeter-wave radar and a Light Detection And Ranging (LiDAR). Since LiDAR can obtain accurate distance and fine spatial resolution due to its short wavelength, it is expected that small objects such as a tire can be detected. However, the conventional LiDAR is equipped with multiple light transmitters and light receivers such as avalanche photo diodes. This causes LiDAR system to be expensive and large in size. Aiming to reduce the cost and size of LiDAR, we employed Single-Photon Avalanche Diode (SPAD) which can be fabricated by CMOS process and easily arrayed. We also developed “Single Chip SPAD Array“ in which the two-dimensional array of SPAD and a signal processing block of range calculation were integrated into a single chip. The light-receiving area was composed of 260x12 SPAD-pixels array. In order to verify the principles, we designed a prototype of LiDAR on…
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Evolution of Gasoline Direct Injection System for Reduction of Real Mode Emission

DENSO Corporation-Soichi Saitoh, Hitoshi Shibata, Masahiro Ookuma
SOKEN-Masahiro Shigenaga
Published 2019-04-02 by SAE International in United States
Continuous improvement of gasoline engine emissions performance is required to further protect the global environment and also the impact of emissions on a local level. During real world driving, transient engine operation and variation in fuel injection, airflow, and wall temperature are key factors to be controlled. Due to the limited opportunity for optimization of engine control, generation of a well-mixed fuel spray is necessary to create a suitable combustion environment to minimize emissions. Optimum spray performance achieves minimum surface wetting as well as promoting evaporation and diffusion if wetting occurs. Improvement in spray homogeneity is an important step to achieve this. Higher fuel pressure is initially considered to achieve improvements, as it is expected to improve mixture formation by reduction of wall wetting due to high atomization and lower penetration, as well as improvement in spray homogeneity. However, excessive pressure should be avoided due to the associated increase in friction losses. This paper shows that improved injector nozzle technology is effective to reduce wall surface adhesion due to high spray dispersion and homogeneity, which…
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Validation Method of Interface Specification for Cooperative Control of Individual Systems

DENSO Corporation-Hiroshi Yamaguchi, Naoya Tsuchiya
Published 2019-04-02 by SAE International in United States
As automotive electronic systems aiming for a safe and secure automobile society continue to develop, the control specifications of the ECU are becoming increasingly complex. When attempting to validate control specifications that cooperatively control different control specifications, control specification developers must consider various validation viewpoints. They narrow down the validation viewpoints based on rules from past experience, describe timing charts, and validate the specifications. However, due to complicated specifications, empirical rules do not pass, and specification mismatches are often found after actual systems completion. On the other hand, a block diagram simulator is a tool to verify control specifications. Since these tools are aimed at modeling and verifying the system design, it is efficient to describe how to implement the system. However, first it is necessary to verify the consistency between the model and the specifications. It is inefficient to verify the specification itself. In order to respond to complicated control specifications, we are working to build the simulation environment necessary to efficiently validate specifications in the specification design phase. In this paper, we describe…
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Ignition and Soot Formation/Oxidation Characteristics of Compositionally Unique International Diesel Blends

DENSO Corporation-Naoki Watanabe, Naoki Kurimoto
Sandia National Laboratories-Scott Skeen, Emre Cenker, Koji Yasutomi, Lyle Pickett
Published 2019-04-02 by SAE International in United States
With the global adoption of diesel common rail systems and the wide variation in composition of local commercial fuels, modern fuel injection systems must be robust against diverse fuel properties. To bridge the knowledge gap on the effects of compositional variation for real commercial fuels on spray combustion characteristics, the present work quantifies ignition and soot formation/oxidation in three unique, international diesel blends. Schlieren imaging, excited-state hydroxyl radical (OH*) chemiluminescence imaging and diffused back-illumination extinction imaging were employed to quantify vapor penetration, ignition, and soot formation and oxidation for high-pressure sprays in a constant-volume, pre-burn chamber. The three fuels were procured from Finland, Japan and Brazil and have cetane numbers of 64.1, 56.1 and 45.4, respectively. In addition to ignition delay times, the high-speed OH* chemiluminescence imaging diagnostic yields the ignition location and the transient lift-off lengths. Time-resolved, two-dimensional soot optical extinction (KL) images were obtained using a diffused back-illumination extinction imaging diagnostic, and these images were integrated to yield the time-resolved total soot mass. Short injection durations were selected to allow imaging of the…
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Thin Ceiling Circulator to Enhance Thermal Comfort and Cabin Space

DENSO Corporation-Toshinori Ochiai, Shuzo Oda, Masaharu Sakai, Syunsuke Ishiguro
Published 2019-04-02 by SAE International in United States
In hot climate regions, there is demand for improved thermal comfort for rear occupants in vehicles not equipped with a rear air conditioner. One solution to this challenge is a circulator mounted on the ceiling. The circulator is a product designed to enhance thermal comfort for occupants by circulating the air in the cabin. The conventional circulator design, which employs a cross flow fan with a large cross section, juts into the cabin space, because it is difficult to package. Consequently, the challenge for the circulator is to provide thermal comfort for rear occupants while taking up the minimum cabin space under the ceiling.To solve this challenge, that is, to enable a substantially thinner structure, while retaining the same level of air flow delivered as before for the same thermal comfort as the conventional circulator, we divided the structure into an air outlet and an air blower. For the air outlet, it is technically necessary to improve the air flow volume gain factor (= volume of air delivered/volume of air blown out) acting in inducing…
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Analysis of Tribofilm Formed by Electric Brush Sliding for Long Life Starter Motor

DENSO Corporation-Taro Fukuda
Published 2019-04-02 by SAE International in United States
Global exhaust emission regulations are becoming stricter, and vehicles equipped with the idle stop system (ISS) are increasing. Recently, starters for vehicles equipped with ISS are required to improve operation feel when speedily restarted. To satisfy this demand, starters must rotate at higher rotational speeds, and heavier wear in their brushes may cause problems. Tribofilm formed on commutators surface by the brush sliding is an important factor in the brush commutator wear, because tribofilm is said to have a property to increase lubricity and decrease mechanical wear in brushes and commutator, as well as to improve commutation and decrease arc wear. Therefore, for reducing brush commutator wear, it is considered effective to promote film formation by improving materials. However, few researches have been conducted to evaluate the relationship between brush materials and tribofilm formation. In this research, we investigated the influence of the brush materials on tribofilm formation and its mechanism. We conducted brush durability tests changing the amount of WS2 and the kind of graphite, and analyzed the hardness of the tribofilm formed by…
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Development of High Accuracy NOx Sensor

DENSO Corporation-Yusukie Kawamoto, Yusuke Todo
SOKEN Inc.-Hironobu Shimokawa
Published 2019-04-02 by SAE International in United States
This paper presents an improvement in the accuracy of NOx sensors at high NOx concentration regions by optimizing the manufacturing process, sensor electrode materials and structure, in order to suppress the deterioration mechanism of sensor electrodes. Though NOx sensors generally consist of Pt/Au alloy based oxygen pump electrodes and Pt/Rh alloy based sensor electrodes, detailed experimental analysis of aged NOx sensors showed changes in the surface composition and morphology of the sensor electrode. The surface of the sensor electrode was covered with Au, which is not originally contained in the electrode, resulting in a diminished active site for NOx detection on the sensor electrode and a decrease in sensor output. Theoretical analysis using CAE with molecular dynamics supported that Au tends to be concentrated on the surface of the sensor electrode. Microstructural analysis revealed the agglomeration of noble metal particles in the sensor electrode, which was another contributor to the decrease in sensor output. The optimal manufacturing process, electrode material, and structure were proposed by estimating the mechanism of sensor output deterioration. Controlling the oxygen…
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Maximizing Coasting of 48 V Vehicles with Cold-Storage Evaporator

DENSO Corporation-Markus Özbek, Shin Nishida, Matteo Biglia, Vipul Kohli, Atsushi Inaba, Tibor Györög, Michio Nishikawa PhD
Published 2018-05-30 by SAE International in United States
One of the main features of 48 V vehicles is the ability to coast at high speeds with the Internal Combustion Engine (ICE) off. This can be realized due to the high torque and power the 48 V motor-generator provides which allows a quick and smooth re-cranking of the ICE. The coasting feature reduces the fuel consumption depending on frequency and duration of the coasting events. This depends in turn on driving pattern, driving style, State-of-Charge of the 48 V and 12 V batteries and the air-conditioning (A/C) system.In summer, if the A/C runs with a mechanical belt-driven compressor, the cabin inlet air temperature from the evaporator inevitably increases during each coasting event as the ICE turns off and cannot operate the compressor. If the evaporator temperature reaches a certain threshold at which the cabin comfort is noticeably affected, the ICE is re-cranked for resuming air-conditioning. This operation during vehicle deceleration and vehicle standstill is inefficient as fuel is consumed solely for operating the A/C. Therefore, it is beneficial for fuel consumption if the evaporator maintains low temperature for…
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Pressure Sensor Module for High Temperature,High Pressure, and Quick Response

DENSO Corporation-Yasutake Ura, Koji Oya
Published 2018-04-03 by SAE International in United States
According to the advance of engine control development, demands for direct sensing of physical quantity have been growing. Regarding pressure sensing, key properties for direct sensing are robustness against high temperature and pressure, and response time in addition to accuracy. In this work, a pressure sensor module with these key properties was developed. First of all, a piezoelectric device was selected as a suitable sensing principle for the required properties because of its thermally stable piezoelectric effect and potential for simple installation structure. Regarding robustness against temperature, the sensor module was designed to form thermal isolation layer with outer housing which is optimized according to its application. Regarding robustness against pressure and response time, breakage of the piezoelectric element is the main technical issue. Based on FEM analysis, a bounce of piezoelectric element in the sensor structure was proven to be the main cause of the element breakage. To prevent piezoelectric element bounce, a pre-load design method was developed as a countermeasure. Regarding high accuracy, the piezoelectric sensor module was modeled as an equivalent spring…
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Development of High Accuracy and Quick Light-off NOx Sensor

DENSO Corporation-Yusuke Todo, Hiroki Ichikawa, Hiroaki Yotou
Toyota Motor Corporation-Keiichiro Aoki, Masashi Kawai
Published 2018-04-03 by SAE International in United States
For the purpose of coping with the strengthening of NOx exhaust gas control and fuel consumption control, it is indispensable to improve the NOx purification capacity. In view of this, vehicle manufacturers are in the course of developing high performance SCR (Selective Catalytic Reduction) systems [1, 2]. For such SCR systems to be realized, high precision NOx sensors for carrying out urea injection quantity control and SCR degradation diagnosis are absolutely indispensable. Detection of NOx concentration by means of a NOx sensor is generally performed as follows: O2 is discharged by means of an O2 detection electrode; remaining NOx is decomposed by a NOx detection electrode; NOx concentration is then detected as electric current that flows when oxygen ions are conduct through solid electrolyte. In order to detect NOx of ppm-order, it is necessary to detect minute current of nA-order with high accuracy. Very small amounts of residual O2 and conducted electrons (having temperature characteristics) that flow in solid electrolyte constitute causal factors for accuracy errors. In order to cancel these causal factors for errors,…
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